Thermal Gradient Holes At Waunita Hot Springs Geothermal Area...
holes Additional References Retrieved from "http:en.openei.orgwindex.php?titleThermalGradientHolesAtWaunitaHotSpringsGeothermalArea(Zacharakis,1981)&oldid762...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
Geothermal Area (Farrar, Et Al., 2003) Exploration Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1998 -...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
Gradient Holes At Long Valley Caldera Geothermal Area (Conservation, 2009) Exploration Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal...
Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski...
Warpinski, Et Al., 2004) Exploration Activity Details Location Lake City Hot Springs Area Exploration Technique Thermal Gradient Holes Activity Date Usefulness not indicated...
Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank...
search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank & Ross, 1999) Exploration Activity Details Location...
Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank...
Blue Mountain Geothermal Area (Fairbank & Niggemann, 2004) Exploration Activity Details Location Blue Mountain Geothermal Area Exploration Technique Thermal Gradient Holes Activity...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1978 - 1985 Usefulness useful DOE-funding Unknown...
Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff...
Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff & Bowers, 2005) Exploration Activity Details Location Lightning Dock Geothermal Area Exploration Technique Thermal...
Thermal Gradient Holes At Breitenbush Hot Springs Area (Ingebritsen...
Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Breitenbush Hot Springs Area (Ingebritsen, Et Al., 1993)...
Thermal Gradient Holes At North Brawley Geothermal Area (Matlick...
Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At North Brawley Geothermal Area (Matlick & Jayne, 2008) Exploration...
Thermal Gradient Holes At Lightning Dock Geothermal Area (Arnold...
DOE-funding Unknown Exploration Basis Known shallow hot spot in Animas Valley Notes Four thermal gradient holes were authorized to be drilled by AMEX, but no results were...
Time changes in gradient and observed winds
Carlson, Ronald Dale
1972-01-01T23:59:59.000Z
TIME CHANGES IN GRADIENT AND OBSERVED WINDS A Thesis by RONALD DALE CARLSON Submitted to the Graduate College of Texas A&M University in partial fulfillm=n of the requirement for the degree of MASTER OF SCIENCE MAY 1972 Major Subject...: Meteorology TIME CHANGES IN GRADIENT AND OBSERVED WINDS A Thesis by RONALD D. CARLSON Approved as to style and content by: (Chairman of Co , ee) (Member) (Member) May 1972 ABSTRACT Time Changes in Gradient and Observed Winds. (May 1972) Ronald Dale...
Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management...
Salt Wells Area (Bureau of Land Management, 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Salt Wells Area...
Time (hole?) machines John Byron Manchak
Manchak, John
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
Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit...
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...
Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell...
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...
Thermal Gradient Holes At North Brawley Geothermal Area (Edmunds...
of the North Brawley, Heber, East Mesa, and Salton Sea Geothermal Areas. Notes Well logs, thermal gradient data, and magnetic data were correlated to form a better geologic...
On Space-Time Singularities, Holes, and Extensions
Manchak, John
On Space-Time Singularities, Holes, and Extensions John Byron Manchak*y Here, we clarify the relationship among three space-time conditions of interest: geodesic completeness, hole. In what follows, we consider three space-time conditions of interest: geodesic completeness, hole
Trace-element geochemistry of gradient hole cuttings: Beowawe geothermal area, Nevada
Christensen, O.D.
1980-12-01T23:59:59.000Z
Multielement geochemical analysis of drill cuttings from 26 shallow temperature-gradient drill holes and of surface rock samples reveals trace element distributions developed within these rocks as a consequence of chemical interaction with thermal fluid within the Beowawe geothermal area. The presently discharging thermal fluids are dilute in all components except silica, suggesting that the residence time of these fluids within the thermal reservoir has been short and that chemical interaction with the reservoir rock minimal. Interaction between these dilute fluids and rocks within the system has resulted in the development of weak chemical signatures. The absence of stronger signatures in rocks associated with the present system suggests that fluids have had a similar dilute chemistry for some time. The spatial distribution of elements commonly associated with geothermal systems, such as As, Hg and Li, and neither laterally nor vertically continuous. This suggests that there is not now, nor has there been in the past, pervasive movement of thermal fluid throughout the sampled rock but, instead, that isolated chemical anomalies represent distinct fluid-flow chanels. Discontinuous As, Li and Hg concentrations near White Canyon to the east of the presently active surface features record the effects of chemical interaction of rocks with fluids chemically unlike the presently discharging fluids. The observed trace element distributions suggest that historically the Beowawe area has been the center of more than one hydrothermal event and that the near-surface portion of the present hot-water geothermal system is controlled by a single source fracture, the Malpais Fault, or an intersection of faults at the sinter terrace.
Hot Pot Contoured Temperature Gradient Map
Lane, Michael
2013-06-28T23:59:59.000Z
Temperature gradient contours derived from Oski temperature gradient hole program and from earlier published information.
Hot Pot Contoured Temperature Gradient Map
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Lane, Michael
Temperature gradient contours derived from Oski temperature gradient hole program and from earlier published information.
Time Complexity of a Parallel Conjugate Gradient Solver for Light Scattering Simulations
Hoffmann, Walter
parallelization for distributed memory computers of a preconditioned Conjugate Gradient method, applied to solve of the Conjugate Gradient method is analyzed theoretically. First expressions for the execution time for three, preconditioned conjugate gradient method, data decomposition, time complexity analysis, performance measurement
Top hole drilling with dual gradient technology to control shallow hazards
Elieff, Brandee Anastacia Marie
2006-10-30T23:59:59.000Z
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...
Distinguishing causal time from Minkowski time and a model for the black hole quantum eigenstates
G. 't Hooft
1997-11-18T23:59:59.000Z
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.
Semi-Blind Gradient-Newton CMA and SDD Algorithm for MIMO Space-Time Equalisation
Chen, Sheng
Semi-Blind Gradient-Newton CMA and SDD Algorithm for MIMO Space-Time Equalisation S. Chen, L. HanzoBJ, UK. E-mails: {sqc, lh, htc1e08}@ecs.soton.ac.uk Abstract-- Semi-blind space-time equalisation-directed scheme is then applied to adapt the STE. The proposed semi-blind adaptive STE is capable of converging
Full-waveform inversion in the time domain with an energy-weighted gradient
Zhang, Zhigang [Los Alamos National Laboratory; Huang, Lianjie [Los Alamos National Laboratory; Lin, Youzuo [Los Alamos National Laboratory
2011-01-01T23:59:59.000Z
When applying full-waveform inversion to surface seismic reflection data, one difficulty is that the deep region of the model is usually not reconstructed as well as the shallow region. We develop an energy-weighted gradient method for the time-domain full-waveform inversion to accelerate the convergence rate and improve reconstruction of the entire model without increasing the computational cost. Three different methods can alleviate the problem of poor reconstruction in the deep region of the model: the layer stripping, depth-weighting and pseudo-Hessian schemes. The first two approaches need to subjectively choose stripping depths and weighting functions. The third one scales the gradient with only the forward propagation wavefields from sources. However, the Hessian depends on wavefields from both sources and receivers. Our new energy-weighted method makes use of the energies of both forward and backward propagated wavefields from sources and receivers as weights to compute the gradient. We compare the reconstruction of our new method with those of the conjugate gradient and pseudo-Hessian methods, and demonstrate that our new method significantly improves the reconstruction of both the shallow and deep regions of the model.
Measurement of time dependent fields in high gradient superconducting quadrupoles for the Tevatron
Lamm, M.J.; Coulter, K.; Gourlay, S.; Jaffery, T.S.
1990-10-01T23:59:59.000Z
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.
M. Cvetic; G. W. Gibbons; H. Lu; C. N. Pope
2005-11-09T23:59:59.000Z
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.
Linear and nonlinear time series analysis of the black hole candidate Cygnus X-1
J. Timmer; U. Schwarz; H. U. Voss; I. Wardinski; T. Belloni; G. Hasinger; M. van der Klis; Juergen Kurths
1999-11-10T23:59:59.000Z
We analyze the variability in the X-ray lightcurves of the black hole candidate Cygnus X-1 by linear and nonlinear time series analysis methods. While a linear model describes the over-all second order properties of the observed data well, surrogate data analysis reveals a significant deviation from linearity. We discuss the relation between shot noise models usually applied to analyze these data and linear stochastic autoregressive models. We debate statistical and interpretational issues of surrogate data testing for the present context. Finally, we suggest a combination of tools from linear andnonlinear time series analysis methods as a procedure to test the predictions of astrophysical models on observed data.
White holes and eternal black holes
Stephen D. H. Hsu
2011-11-16T23:59:59.000Z
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.
Campbell, B.; MacKinnon, J.; Bandy, T.R.; Hampton, T.
1996-12-31T23:59:59.000Z
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.
Quantum time uncertainty in Schwarzschild-anti-de Sitter black holes
Galan, Pablo; Mena Marugan, Guillermo A. [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Garay, Luis J. [Departamento de Fisica Teorica II, Universidad Complutense de Madrid, 28040 Madrid (Spain); Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain)
2007-08-15T23:59:59.000Z
The combined action of gravity and quantum mechanics gives rise to a minimum time uncertainty in the lowest order approximation of a perturbative scheme, in which quantum effects are regarded as corrections to the classical spacetime geometry. From the nonperturbative point of view, both gravity and quantum mechanics are treated on equal footing in a description that already contains all possible backreaction effects as those above in a nonlinear manner. In this paper, the existence or not of such minimum time uncertainty is analyzed in the context of Schwarzschild-anti-de Sitter black holes using the isolated horizon formalism. We show that from a perturbative point of view, a nonzero time uncertainty is generically present owing to the energy scale introduced by the cosmological constant, while in a quantization scheme that includes nonperturbatively the effects of that scale, an arbitrarily high time resolution can be reached.
Beal, Jacob
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 ...
Real-time solar wind prediction based on SDO/AIA coronal hole data
Rotter, T; Temmer, M; Vrsnak, B
2015-01-01T23:59:59.000Z
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 ...
Inertial blob-hole symmetry breaking in magnetised plasma filaments
Kendl, Alexander
2015-01-01T23:59:59.000Z
Symmetry breaking between the propagation velocities of magnetised plasma filaments with large positive (blob) and negative (hole) amplitudes, as implied by a dimensional analysis scaling, is studied with global ("full-n") non-Boussinesq gyrofluid computations, which include finite inertia effects through nonlinear polarisation. Interchange blobs on a flat density background have higher inertia and propagate more slowly than holes. In the presence of a large enough density gradient, the effect is reversed: blobs accelerate down the gradient and holes are slowed in their propagation up the gradient. Drift wave blobs spread their initial vorticity rapidly into a fully developed turbulent state, whereas primary holes can remain coherent for many eddy turnover times. The results bear implications for plasma edge zonal flow evolution and tokamak scrape-off-layer transport.
Classical stability of black hole Cauchy horizons in two-dimensional asymptotically flat space-times
A. Fabbri
1996-07-04T23:59:59.000Z
In this paper we analyse the stability of black hole Cauchy horizons arising in a class of 2d dilaton gravity models. It is shown that due to the characteristic asymptotic Rindler form of the metric of these models, time dependent gravitational perturbations generated in the external region do not necessarily blow-up when propagated along the Cauchy horizon. There exists, in fact, a region of nonzero measure in the space of the parameters characterizing the solutions such that both instability and mass inflation are avoided. This is a new result concerning asymptotically flat space-times, not shared by the well-known solutions of General Relativity. Despite this fact, however, quantum back-reaction seems to produce a scalar curvature singularity there.
Gradient Symplectic Algorithms for Solving the Schroedinger Equation with Time-Dependent Potentials
Chin, S A
2002-01-01T23:59:59.000Z
We show that the method of factorizing the evolution operator to fourth order with purely positive coefficients, in conjunction with Suzuki's method of implementing time-ordering of operators, produces a new class of powerful algorithms for solving the Schroedinger equation with time-dependent potentials. When applied to the Walker-Preston model of a diatomic molecule in a strong laser field, these algorithms can have fourth order error coefficients that are three orders of magnitude smaller than the Forest-Ruth algorithm using the same number of Fast Fourier Transforms. When compared to the second order split-operator method, some of these algorithms can achieve comparable convergent accuracy at step sizes 50 times as large. Morever, we show that these algorithms belong to a one-parameter family of algorithms, and that the parameter can be further optimized for specific applications.
Gradient Symplectic Algorithms for Solving the Schroedinger Equation with Time-Dependent Potentials
S. A. Chin; C. R. Chen
2002-03-05T23:59:59.000Z
We show that the method of factorizing the evolution operator to fourth order with purely positive coefficients, in conjunction with Suzuki's method of implementing time-ordering of operators, produces a new class of powerful algorithms for solving the Schroedinger equation with time-dependent potentials. When applied to the Walker-Preston model of a diatomic molecule in a strong laser field, these algorithms can have fourth order error coefficients that are three orders of magnitude smaller than the Forest-Ruth algorithm using the same number of Fast Fourier Transforms. When compared to the second order split-operator method, some of these algorithms can achieve comparable convergent accuracy at step sizes 50 times as large. Morever, we show that these algorithms belong to a one-parameter family of algorithms, and that the parameter can be further optimized for specific applications.
Clark, James; Simon, Christoph
2012-01-01T23:59:59.000Z
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.
Compact real-time 2-D gradient-based analog VLSI motion sensor
Deutschmann, Rainer
the sensor might be favourably applied in industrial applications. Keywords: analog VLSI, motion sensor selectivity even for very low contrast input is demonstrated. As application it is shown how the pixel, smart vision sensor, parallel image processing, real-time computation, optical ow, machine vision, robot
Simulation of Water Level Fluctuations in Kettle Holes Using a Time Series Model
Kleyer, Michael
online: 21 April 2011 # Society of Wetland Scientists 2011 Abstract Kettle holes are widespread in the future, conservation strategies for kettle holes should include the effects of climate change. Keywords). This number is comparable with the wetland loss in the United States (Dahl 1990; Johnston 1994), Japan
Stability of Gauss-Bonnet black holes in anti-de Sitter space-time against scalar field condensation
Brihaye, Yves [Physique-Mathematique, Universite de Mons-Hainaut, 7000 Mons (Belgium); Hartmann, Betti [School of Engineering and Science, Jacobs University Bremen, 28759 Bremen (Germany)
2011-10-15T23:59:59.000Z
We study the stability of static, hyperbolic Gauss-Bonnet black holes in (4+1)-dimensional anti-de Sitter (AdS) space-time against the formation of scalar hair. Close to extremality the black holes possess a near-horizon topology of AdS{sub 2}xH{sup 3} such that within a certain range of the scalar field mass one would expect that they become unstable to the condensation of an uncharged scalar field. We confirm this numerically and observe that there exists a family of hairy black hole solutions labeled by the number of nodes of the scalar field function. We construct explicit examples of solutions with a scalar field that possesses zero nodes, one node, and two nodes, respectively, and show that the solutions with nodes persist in the limit of Einstein gravity, i.e. for vanishing Gauss-Bonnet coupling. We observe that the interval of the mass for which scalar field condensation appears decreases with increasing Gauss-Bonnet coupling and/or with increasing node number.
Late-Time Dynamics of Scalar Fields on Rotating Black Hole Backgrounds
William Krivan
1999-07-08T23:59:59.000Z
Motivated by results of recent analytic studies, we present a numerical investigation of the late-time dynamics of scalar test fields on Kerr backgrounds. We pay particular attention to the issue of mixing of different multipoles and their fall-off behavior at late times. Confining ourselves to the special case of axisymmetric modes with equatorial symmetry, we show that, in agreement with the results of previous work, the late-time behavior is dominated by the lowest allowed l-multipole. However the numerical results imply that, in general, the late-time fall-off of the dominating multipole is different from that in the Schwarzschild case, and seems to be incompatible with a result of a recently published analytic study.
Thermal Gradient Holes | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating SolarElectric Coop, Inc Place:InnovationFunds-BusinessOhio EnvironmentalTheSEFI Jump
Baras, P.; Seimenis, I.; Sandilos, P.; Vlahos, L.; Bieganski, T.; Georgiou, E.; Pantelis, E.; Papagiannis, P.; Sakelliou, L. [Philips Hellas Medical Systems, 44 Kifissias Ave., Maroussi 151 25, Athens (Greece); Department of Radiology, Medical School, University of Athens, Areteion Hospital, 76 Vas. Sofias Ave., 115 28 Athens (Greece) and Medical Physics Department, Hygeia Hospital, Kiffisias Avenue, 24 Erythrou Stavrou, Marousi, 151 23, Athens (Greece); Department of Radiology, Mother's Memorial Hospital, Rzgowska 281/289, 93-388, Lodz (Poland); Medical Physics Department, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece)
2005-11-15T23:59:59.000Z
The use of magnetic resonance imaging as a readout method for polymer gel dosimetry commonly involves long imaging sessions, particularly when high spatial resolution is required in all three dimensions, for the investigation of dose distributions with steep dose gradients and stringent dose delivery specifications. In this work, a volume selective turbo spin echo (TSE) pulse sequence is compared to the established Carr-Purcell-Meiboom-Gill (CPMG) multiecho acquisition with regard to providing accurate dosimetric results in significantly reduced imaging times. Polyethylene glycol diacrylate based (PABIG) gels were irradiated and subsequently scanned to obtain R2 relaxation rate measurements, using a CPMG multiecho sequence and a dual echo TSE utilizing an acceleration (turbo) factor of 64. R2 values, plotted against corresponding Monte Carlo dose calculations, provided calibration data of PABIG gels dose response over a wide dose range. A linear R2 versus dose relationship was demonstrated for both sequences with TSE results presenting reduced dose sensitivity. Although TSE data were found to deviate from linearity at lower doses compared to CPMG data, a relatively wide dynamic dose range of response extending up to approximately 100 Gy was observed for both sequences. The TSE and CPMG sequences were evaluated with a brachytherapy irradiation using a high dose rate {sup 192}Ir source and a gamma knife stereotactic radiosurgery irradiation with a single 4 mm collimator helmet shot. Dosimetric results obtained with the TSE and CPMG are shown to compare equally well with the expected dose distributions for these irradiations. The 60-fold scan time reduction achieved with TSE implies that this sequence could prove to be a useful tool for the introduction of polymer gel dosimetry in clinical radiation therapy applications involving high doses and steep dose gradients.
P. Arevalo; P. Uttley
2005-12-15T23:59:59.000Z
The fluctuating accretion model of Lyubarskii (1997) and its extension by Kotov et al. (2001), seeks to explain the spectral-timing properties of the X-ray variability of accreting black holes in terms of inward-propagating mass accretion fluctuations produced at a broad range of radii. The fluctuations modulate the X-ray emitting region as they move inwards and can produce temporal-frequency-dependent lags between energy bands, and energy-dependent power spectral densities (PSDs) as a result of the different emissivity profiles, which may be expected at different X-ray energies. Here we use a simple numerical implementation to investigate in detail the X-ray spectral-timing properties of the model and their relation to several physically interesting parameters, namely the emissivity profile in different energy bands, the geometrical thickness and viscosity parameter of the accretion flow, the strength of damping on the fluctuations and the temporal coherence (measured by the `quality-factor', Q) of the fluctuations introduced at each radius. We find that a geometrically thick flow with large viscosity parameter is favoured, and confirm that the predicted lags are quite robust to changes in the emissivity profile, and physical parameters of the accretion flow, which may help to explain the similarity of the lag spectra in the low/hard and high/soft states of Cyg X-1. We also demonstrate the model regime where the light curves in different energy bands are highly spectrally coherent. We compare model predictions directly to X-ray data from the Narrow Line Seyfert~1 galaxy NGC 4051 and the BHXRB Cyg X-1 in its high/soft state and show that this general scheme can reproduce simultaneously the time lags and energy-dependence of the PSD.
Philippe Laurent; Lev Titarchuk
2001-10-11T23:59:59.000Z
We demonstrate that a X-ray spectrum of a converging inflow (CI) onto a black hole is the sum of a thermal (disk) component and the convolution of some fraction of this component with the Comptonization spread (Green's) function. The latter component is seen as an extended power law at energies much higher than the characteristic energy of the soft photons. We show that the high energy photon production (source function) in the CI atmosphere is distributed with the characteristic maximum at about the photon bending radius, 1.5r_S, independently of the seed (soft) photon distribution. We show that high frequency oscillations of the soft photon source in this region lead to the oscillations of the high energy part of the spectrum but not of the thermal component. The high frequency oscillations of the inner region are not significant in the thermal component of the spectrum. We further demonstrate that Doppler and recoil effects (which are responsible for the formation of the CI spectrum) are related to the hard (positive) and soft (negative) time lags between the soft and hard photon energy channels respectively.
Block-conjugate-gradient method
McCarthy, J.F. (Department of Physics, Indiana University, Bloomington, Indiana 47405 (US))
1989-09-15T23:59:59.000Z
It is shown that by using the block-conjugate-gradient method several, say {ital s}, columns of the inverse Kogut-Susskind fermion matrix can be found simultaneously, in less time than it would take to run the standard conjugate-gradient algorithm {ital s} times. The method improves in efficiency relative to the standard conjugate-gradient algorithm as the fermion mass is decreased and as the value of the coupling is pushed to its limit before the finite-size effects become important. Thus it is potentially useful for measuring propagators in large lattice-gauge-theory calculations of the particle spectrum.
Introduction Conjugate Gradient Method
Vuik, Kees
Introduction Conjugate Gradient Method Deflation Domain Decomposition Research Master Thesis Presentation #12;Introduction Conjugate Gradient Method Deflation Domain Decomposition Research Plaxis Finite Kaliszka Master Thesis Literature Study Presentation #12;Introduction Conjugate Gradient Method Deflation
Evaluation of liquid lift approach to dual gradient
Okafor, Ugochukwu Nnamdi
2009-05-15T23:59:59.000Z
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...
Evaluation of liquid lift approach to dual gradient drilling
Okafor, Ugochukwu Nnamdi
2008-10-10T23:59:59.000Z
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...
Gradient elution in capillary electrochromatography
Anex, D.; Rakestraw, D.J. [Sandia National Labs., Livermore, CA (United States); Yan, Chao; Dadoo, R.; Zare, R.N. [Stanford Univ., CA (United States). Dept. of Chemistry
1997-08-01T23:59:59.000Z
In analogy to pressure-driven gradient techniques in high-performance liquid chromatography, a system has been developed for delivering electroosmotically-driven solvent gradients for capillary electrochromatography (CEC). Dynamic gradients with sub-mL/min flow rates are generated by merging two electroosmotic flows that are regulated by computer-controlled voltages. These flows are delivered by two fused-silica capillary arms attached to a T-connector, where they mix and then flow into a capillary column that has been electrokinetically packed with 3-mm reversed-phase particles. The inlet of one capillary arm is placed in a solution reservoir containing one mobile phase and the inlet of the other is placed in a second reservoir containing a second mobile phase. Two independent computer-controlled programmable high-voltage power supplies (0-50 kV)--one providing an increasing ramp and the other providing a decreasing ramp--are used to apply variable high-voltage potentials to the mobile phase reservoirs to regulate the electroosmotic flow in each arm. The ratio of the electroosmotic flow rates between the two arms is changed with time according to the computer-controlled voltages to deliver the required gradient profile to the separation column. Experiments were performed to confirm the composition of the mobile phase during a gradient run and to determine the change of the composition in response to the programmed voltage profile. To demonstrate the performance of electroosmotically-driven gradient elution in CEC, a mixture of 16 polycyclic aromatic hydrocarbons (PAHs) was separated in less than 90 minutes. This gradient technique is expected to be well-suited for generating not only solvent gradients in CEC, but also other types of gradients such as pH- and ionic-strength gradients in capillary electrokinetic separations and analyses.
Paris-Sud XI, UniversitÃ© de
Piping flow erosion in water retaining structures: inferring erosion rates from hole erosion tests-en-Provence Cedex 5, France E-mail: stephane.bonelli@cemagref.fr Abstract The piping flow erosion process, involving structures. Such a pipe can be imputed to roots or burrows. The coefficient of erosion must be known in order
Gradient zone-boundary control in salt-gradient solar ponds
Hull, J.R.
1982-09-29T23:59:59.000Z
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.
P. K. Townsend
1997-07-04T23:59:59.000Z
Lecture notes for a 'Part III' course 'Black Holes' given in DAMTP, Cambridge. The course covers some of the developments in Black Hole physics of the 1960s and 1970s.
Valeri P. Frolov; Andrei V. Frolov
2014-12-30T23:59:59.000Z
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.
Quasilinear Carbon Transport In An Impurity Hole Plasma In LHD
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
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.
Converting Level Set Gradients to Shape Gradients
Radke, Rich
distance function (SDF) associated with a shape, and differentiate these energies with respect to the SDF to the SDF. We discuss some problematic gradients from the literature, show how they can easily be fixed function (SDF) of , i.e. the function that associates any point x with the signed distance (x) = Â±d
Gabor, Nathaniel M.
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 ...
A. Vikhlinin
1999-06-09T23:59:59.000Z
In X-ray binaries, several percent of the compact object luminosity is intercepted by the surface of the normal companion and re-radiated through Compton reflection and the K-fluorescence. This reflected emission follows the variability of the compact object with a delay approximately equal to the orbital radius divided by the speed of light. This provides the possibility of measuring the orbital radius and thus substantially refining the compact object mass determination compared to using optical data alone. We demonstrate that it may be feasible to measure the time delay between the direct and reflected emission using cross-correlation of the light curves observed near the Kalpha line and above the K-edge of neutral iron. In the case of Cyg X-1, the time delay measurement is feasible with a 300--1000 ksec observation by a telescope with a 1000 cm^2 effective area near 6.4 keV and with a ~5eV energy resolution. With longer exposures, it may be possible to obtain mass constraints even if an X-ray source in the binary system lacks an optical counterpart.
Measurement of thermodynamics using gradient flow
Masakiyo Kitazawa; Masayuki Asakawa; Tetsuo Hatsuda; Takumi Iritani; Etsuko Itou; Hiroshi Suzuki
2014-12-15T23:59:59.000Z
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.
second-order convex splitting schemes for gradient flows with ...
2011-11-08T23:59:59.000Z
Abstract. We construct unconditionally stable, unconditionally uniquely solvable, and second-order accurate (in time) schemes for gradient flows with energy of ...
Conjugate Gradient Method Numerisches Rechnen
Conjugate Gradient Method Numerisches Rechnen (für Informatiker) M. Grepl J. Berger & J.T. Frings Numerisches Rechnen #12;Conjugate Gradient Method The Quadratic Form Steepest Descent Conjugate Directions/Gradients IGPM, RWTH Aachen Numerisches Rechnen #12;Conjugate Gradient Method The Quadratic Form Steepest Descent
Silverstein, Daniel W.; Govind, Niranjan; van Dam, Hubertus JJ; Jensen, Lasse
2013-12-10T23:59:59.000Z
A parallel implementation of analytical time-dependent density functional theory gra- dients is presented for the quantum chemistry program NWChem. The implementation is based on the Lagrangian approach developed by Furche and Ahlrichs. To validate our implementation, we first calculate the Stokes shifts for a range of organic dye molecules using a diverse set of exchange-correlation functionals (traditional density functionals, global hybrids and range-separated hybrids) followed by simulations of the one-photon absorption and resonance Raman scattering spectrum of the phenoxyl radical, the well-studied dye molecule rhodamine 6G and a molecular host-guest complex (TTF?CBPQT4+). The study of organic dye molecules illustrates that B3LYP and CAM-B3LYP generally give the best agreement with experimentally determined Stokes shifts unless the excited state is a charge transfer state. Absorption, resonance Raman, and fluorescence simulations for the phenoxyl radical indicate that explicit solvation may be required for accurate characterization. For the host-guest complex and rhodamine 6G, it is demonstrated that absorption spectra can be simulated in good agreement with experiment for most exchange-correlation functionals. However, because one-photon absorption spectra generally lack well-resolved vibrational features, resonance Raman simulations are necessary to evaluate the accuracy of the exchange-correlation functional for describing a potential energy surface.
Thermal Gradient Holes At Fenton Hill HDR Geothermal Area (Purtymun...
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....
Thermal Gradient Holes At Northern Basin & Range Region (Pritchett...
Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoreticalcomputer simulation tests of various methods on eight hypothetical 'model' basing-and-range...
Thermal Gradient Holes At Central Nevada Seismic Zone Region...
Activity Date Usefulness useful DOE-funding Unknown Notes NOTE: These are theoreticalcomputer simulation tests of various methods on eight hypothetical 'model' basing-and-range...
Thermal Gradient Holes At Walker-Lane Transitional Zone Region...
Date Usefulness not useful DOE-funding Unknown Notes NOTE: These are theoreticalcomputer simulation tests of various methods on eight hypothetical 'model' basing-and-range...
Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff...
R.A. Cunniff, R.L. Bowers (2003) Final Report: Enhanced Geothermal Systems Technology Phase II: Animas Valley, New Mexico Additional References Retrieved from "http:...
Thermal Gradient Holes At Roosevelt Hot Springs Geothermal Area...
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...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
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...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
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....
Temperature, heat flow maps and temperature gradient holes | Open Energy
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Thermal Gradient Holes At Central Nevada Seismic Zone Region (Pritchett,
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Thermal Gradient Holes At Coso Geothermal Area (1974) | Open Energy
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Thermal Gradient Holes At Coso Geothermal Area (1976) | Open Energy
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Thermal Gradient Holes At Long Valley Caldera Geothermal Area
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revisionEnvReviewNonInvasiveExplorationUT-gTaguspark JumpDetective Jump to:theEnergyEnergyOpen Energy1978)
Thermal Gradient Holes At Waunita Hot Springs Geothermal Area (Zacharakis,
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Category:Thermal Gradient Holes | Open Energy Information
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating SolarElectricEnergyCTBarreis aCallahanWindSyracuse, NY Jump to:Operators Jump to:page?
Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank &
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformation
Thermal Gradient Holes At Breitenbush Hot Springs Area (Ingebritsen, Et
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl., 1993) | Open
Thermal Gradient Holes At Hualalai Northwest Rift Area (Thomas, 1986) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,Open Energy
Thermal Gradient Holes At Long Valley Caldera Geothermal Area (Lachenbruch,
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,OpenEt Al.,
Thermal Gradient Holes At Mt Princeton Hot Springs Geothermal...
the area References J. Held, F. Henderson (2012) New developments in Colorado geothermal energy projects Additional References Retrieved from "http:en.openei.orgw...
Results of temperature gradient and heat flow in Santiam Pass Area, Oregon, Volume 1
Cox, B.L.; Gardner, M.C.; Koenig, J.B.
1981-08-01T23:59:59.000Z
The conclusions of this report are: (1) There is a weakly defined thermal anomaly within the area examined by temperature-gradient holes in the Santiam Pass area. This is a relict anomaly showing differences in permeability between the High Cascades and Western Cascades areas, more than a fundamental difference in shallow crustal temperatures. (2) The anomaly as defined by the 60 F isotherms at 400 feet follows a north-south trend immediately westward of the Cascade axis in the boundary region. It is clear that all holes spudded into High Cascades rocks result in isothermal and reversal gradients. Holes spudded in Western Cascades rocks result in positive gradients. (3) Cold groundwater flow influences and masks temperature gradients in the High Cascades to a depth of at least 700 feet, especially eastward from the major north-south trending faults. Pleistocene and Holocene rocks are very permeable aquifers. (4) Shallow gradient drilling in the lowlands westward of the faults provides more interpretable information than shallow drilling in the cold-water recharge zones. Topographic and climatological effects can be filtered out of the temperature gradient results. (5) The thermal anomaly seems to have 2 centers: one in the Belknap-Foley area, and one northward in the Sand Mountain area. The anomalies may or may not be connected along a north-south trend. (6) A geothermal effect is seen in holes downslope of the Western-High Cascade boundary. Mixing with cold waters is a powerful influence on temperature gradient data. (7) The temperature-gradient program has not yet examined and defined the geothermal resources potential of the area eastward of the Western Cascades-High Cascades boundary. Holes to 1500-2000 feet in depth are required to penetrate the high permeability-cold groundwater regime. (8) Drilling conditions are unfavorable. There are very few accessible level drill sites. Seasonal access problems and environmental restrictions together with frequent lost circulation results in very high costs per foot drilled.
Black Hole Interior Mass Formula
Parthapratim Pradhan
2014-05-06T23:59:59.000Z
We argue by explicit computations that, although the area product, horizon radii product, entropy product and \\emph {irreducible mass product} of the event horizon and Cauchy horizon are universal, the \\emph{surface gravity product}, \\emph{surface temperature product} and \\emph{Komar energy product} of the said horizons do not seem to be universal for Kerr-Newman (KN) black hole space-time. We show the black hole mass formula on the \\emph{Cauchy horizon} following the seminal work by Smarr\\cite{smarr} for the outer horizon. We also prescribed the \\emph{four} laws of black hole mechanics for the \\emph{inner horizon}. New definition of the extremal limit of a black hole is discussed.
Conjugate Gradient Methods in Confirmatory Factor Analysis
Jamshardian, Mortaza; Jennrich, Robert
1993-01-01T23:59:59.000Z
R. I. (1988), "Conjugate Gradient Methods in Confirmatoryapply generalized conjugate gradient methods in an attemptby used. The conjugate gradient method, which is simple and
Conjugate Gradient Acceleration of the EM Algorithm
Mortaza Jamshidian; Robert Jennrich
2011-01-01T23:59:59.000Z
R. I. (1988), "Conjugate Gradient Methods in Confirmatoryapply generalized conjugate gradient methods in an attemptby used. The conjugate gradient method, which is simple and
Fourier Accelerated Conjugate Gradient Lattice Gauge Fixing
R. J. Hudspith
2014-05-22T23:59:59.000Z
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.
Absorption cross section of RN black hole
Sini R.; V. C. Kuriakose
2007-08-23T23:59:59.000Z
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.
Vranjes, J
2015-01-01T23:59:59.000Z
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 ...
Pumpernickel Valley Geothermal Project Thermal Gradient Wells
Z. Adam Szybinski
2006-01-01T23:59:59.000Z
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, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined with geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley – Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermal production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. 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 fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well – Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for
High-gradient compact linear accelerator
Carder, Bruce M. (205 Rogue River Hwy., Gold Hill, OR 97525)
1998-01-01T23:59:59.000Z
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.
High-gradient compact linear accelerator
Carder, B.M.
1998-05-26T23:59:59.000Z
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.
Topological Black Holes in Quantum Gravity
J. Kowalski-Glikman; D. Nowak-Szczepaniak
2000-07-31T23:59:59.000Z
We derive the black hole solutions with horizons of non-trivial topology and investigate their properties in the framework of an approach to quantum gravity being an extension of Bohm's formulation of quantum mechanics. The solutions we found tend asymptotically (for large $r$) to topological black holes. We also analyze the thermodynamics of these space-times.
Hierarchically deflated conjugate gradient
P A Boyle
2014-02-11T23:59:59.000Z
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.
Geodesics and Geodesic Deviation in static Charged Black Holes
Ragab M. Gad
2010-03-03T23:59:59.000Z
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.
Gradient Sliding for Composite Optimization
2014-06-11T23:59:59.000Z
Noname manuscript No. (will be inserted by the editor). Gradient Sliding for Composite Optimization. Guanghui Lan the date of receipt and acceptance should ...
alternating gradient synchrotron: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
sources also have the advantage of a time structure with a high peak neutron flux. The basic requirement is for a... Bryant, P J 1995-01-01 36 Gradient House. Open...
Hankiewicz, EM; Li, J.; Jungwirth, T.; Niu, Q.; Shen, SQ; Sinova, Jairo.
2005-01-01T23:59:59.000Z
We study theoretically the spin-Hall effect as well as its reciprocal phenomenon (a transverse charge current driven by a spin-dependent chemical potential gradient) in electron and hole finite size mesoscopic systems. The Landauer...
Energy on black hole spacetimes
Alejandro Corichi
2012-07-18T23:59:59.000Z
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.
Solving a Two-Dimensional Elliptic Model Problem with the Conjugate Gradient Method Using
Gobbert, Matthias K.
Solving a Two-Dimensional Elliptic Model Problem with the Conjugate Gradient Method Using Matrix Preconditioned Conjugate Gradient method in Matlab can be optimized in terms of wall clock time and, more-free Preconditioned Conjugate Gradient method. This superior algorithm computes the same numerical solution to our
Spectroscopy and Thermodynamics of MSW Black Hole
Sebastian, Saneesh
2013-01-01T23:59:59.000Z
We study the thermodynamics and spectroscopy of a 2+1 dimensional black hole pro- posed by Mandal et. al1 . We put the background space time in Kruskal like co-ordinate and find period with respect to Euclidean time. Different thermodynamic quantities like entropy, specific heat, temperature etc are obtained. The adiabatic invariant for the black hole is found out and quantized using Bohr-Sommerfeld quantization rule. The study shows that the area spectrum of MSW black hole is equally spaced and the value of spacing is found to be h bar
Spectroscopy and Thermodynamics of MSW Black Hole
Saneesh Sebastian; V. C. Kuriakose
2013-09-02T23:59:59.000Z
We study the thermodynamics and spectroscopy of a 2+1 dimensional black hole pro- posed by Mandal et. al1 . We put the background space time in Kruskal like co-ordinate and find period with respect to Euclidean time. Different thermodynamic quantities like entropy, specific heat, temperature etc are obtained. The adiabatic invariant for the black hole is found out and quantized using Bohr-Sommerfeld quantization rule. The study shows that the area spectrum of MSW black hole is equally spaced and the value of spacing is found to be h bar
Black Hole Thermodynamics and Electromagnetism
Burra G. Sidharth
2005-07-15T23:59:59.000Z
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.
High field gradient particle accelerator
Nation, J.A.; Greenwald, S.
1989-05-30T23:59:59.000Z
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.
High field gradient particle accelerator
Nation, John A. (Ithaca, NY); Greenwald, Shlomo (Haifa, IL)
1989-01-01T23:59:59.000Z
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.
David Kubiznak; Robert B. Mann
2014-04-08T23:59:59.000Z
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.
Energy conservation for dynamical black holes
Sean A. Hayward
2004-08-03T23:59:59.000Z
An energy conservation law is described, expressing the increase in mass-energy of a general black hole in terms of the energy densities of the infalling matter and gravitational radiation. For a growing black hole, this first law of black-hole dynamics is equivalent to an equation of Ashtekar & Krishnan, but the new integral and differential forms are regular in the limit where the black hole ceases to grow. An effective gravitational-radiation energy tensor is obtained, providing measures of both ingoing and outgoing, transverse and longitudinal gravitational radiation on and near a black hole. Corresponding energy-tensor forms of the first law involve a preferred time vector which plays the role for dynamical black holes which the stationary Killing vector plays for stationary black holes. Identifying an energy flux, vanishing if and only if the horizon is null, allows a division into energy-supply and work terms, as in the first law of thermodynamics. The energy supply can be expressed in terms of area increase and a newly defined surface gravity, yielding a Gibbs-like equation, with a similar form to the so-called first law for stationary black holes.
CONJUGATE GRADIENT WITH SUBSPACE OPTIMIZATION 1 ...
2011-12-25T23:59:59.000Z
last update. Unlike some other conjugate gradient methods, our algorithm attains a theoretical ... The method of conjugate gradients (CG) was introduced by.
Hal M. Haggard; Carlo Rovelli
2014-07-06T23:59:59.000Z
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.
The 1983 Temperature Gradient and Heat Flow Drilling Project for the State of Washington
Korosec, Michael A.
1983-11-01T23:59:59.000Z
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.
Some remarks on black hole thermodynamics
R. Y. Chiao
2011-02-04T23:59:59.000Z
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.
Steven Corley; Ted Jacobson
1998-03-26T23:59:59.000Z
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.
Xerxes D. Arsiwalla; Erik P. Verlinde
2009-02-02T23:59:59.000Z
We study the problem of spatially stabilising four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes kept in external fields we find that taking a continuum limit of Denef et al's multi-center solutions provides a supergravity description of such backgrounds within which a black hole can be trapped in a given volume. This is realised by levitating a black hole over a magnetic dipole base. We comment on how such a construction resembles a mechanical Levitron.
Sean A. Hayward
2009-02-28T23:59:59.000Z
This is a review of current theory of black-hole dynamics, concentrating on the framework in terms of trapping horizons. Summaries are given of the history, the classical theory of black holes, the defining ideas of dynamical black holes, the basic laws, conservation laws for energy and angular momentum, other physical quantities and the limit of local equilibrium. Some new material concerns how processes such as black-hole evaporation and coalescence might be described by a single trapping horizon which manifests temporally as separate horizons.
Variable metric conjugate gradient methods
Barth, T.; Manteuffel, T.
1994-07-01T23:59:59.000Z
1.1 Motivation. In this paper we present a framework that includes many well known iterative methods for the solution of nonsymmetric linear systems of equations, Ax = b. Section 2 begins with a brief review of the conjugate gradient method. Next, we describe a broader class of methods, known as projection methods, to which the conjugate gradient (CG) method and most conjugate gradient-like methods belong. The concept of a method having either a fixed or a variable metric is introduced. Methods that have a metric are referred to as either fixed or variable metric methods. Some relationships between projection methods and fixed (variable) metric methods are discussed. The main emphasis of the remainder of this paper is on variable metric methods. In Section 3 we show how the biconjugate gradient (BCG), and the quasi-minimal residual (QMR) methods fit into this framework as variable metric methods. By modifying the underlying Lanczos biorthogonalization process used in the implementation of BCG and QMR, we obtain other variable metric methods. These, we refer to as generalizations of BCG and QMR.
Gas Exchange, Partial Pressure Gradients,
Riba Sagarra, Jaume
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
Topological Black Holes -- Outside Looking In
R. B. Mann
1997-09-15T23:59:59.000Z
I describe the general mathematical construction and physical picture of topological black holes, which are black holes whose event horizons are surfaces of non-trivial topology. The construction is carried out in an arbitrary number of dimensions, and includes all known special cases which have appeared before in the literature. I describe the basic features of massive charged topological black holes in $(3+1)$ dimensions, from both an exterior and interior point of view. To investigate their interiors, it is necessary to understand the radiative falloff behaviour of a given massless field at late times in the background of a topological black hole. I describe the results of a numerical investigation of such behaviour for a conformally coupled scalar field. Significant differences emerge between spherical and higher genus topologies.
On Higuchi Ghosts and Gradient Instabilities in Bimetric Gravity
Könnig, Frank
2015-01-01T23:59:59.000Z
We discuss the conditions to satisfy the Higuchi bound and to avoid gradient instabilities in the scalar sector for cosmological solutions in singly coupled bimetric gravity theories. We find that in expanding universes the ratio of the scale factors of the reference and observable metric has to increase at all times. This automatically implies a ghost-free helicity-2 sector and enforces a phantom Dark Energy. Furthermore, the condition for the absence of gradient instabilities in the scalar sector will be analyzed. Finally, we discuss whether cosmological solutions, including exotic evolutions like bouncing cosmologies, can exist, in which both the Higuchi ghost and scalar instabilities are absent at all times.
A Quantum Material Model of Static Schwarzschild Black Holes
S. -T. Sung
1997-03-16T23:59:59.000Z
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.
Conjugate Gradient Algorithms Using Multiple Recursions
of Colorado Much is already known about when a conjugate gradient method can be implemented with short and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented that the conjugate gradient method for unitary and shifted unitary matrices can be implemented using a single short
An Introduction to the Conjugate Gradient Method
Zhang, Yi
An Introduction to the Conjugate Gradient Method Without the Agonizing Pain Edition 11 4 Jonathan Abstract The Conjugate Gradient Method is the most prominent iterative method for solving sparse systems, the Conjugate Gradient Method is a composite of simple, elegant ideas that almost anyone can understand
An Introduction to the Conjugate Gradient Method
Shewchuk, Jonathan
An Introduction to the Conjugate Gradient Method Without the Agonizing Pain Edition 1 1 4 Jonathan Abstract The Conjugate Gradient Method is the most prominent iterative method for solving sparse systems, the Conjugate Gradient Method is a composite of simple, elegant ideas that almost anyone can understand
Porting the NAS-NPB Conjugate Gradient
Crawford, T. Daniel
.kr/Center_for_Manycore_Programming/SNU_NPB_Suite.html NPB Benchmarks #12;! "A conjugate gradient method is used to compute an approximation to the smallestPorting the NAS-NPB Conjugate Gradient Benchmark to CUDA NVIDIA Corporation #12;Outline ! Overview coding methodologies and architectures. ! Suite of benchmarks: ! Integer Sort ! Conjugate Gradient ! CFD
Accurate conjugate gradient methods for shifted systems
Sleijpen, Gerard
Accurate conjugate gradient methods for shifted systems by Jasper van den Eshof and Gerard L. G CONJUGATE GRADIENT METHODS FOR SHIFTED SYSTEMS JASPER VAN DEN ESHOF AND GERARD L. G. SLEIJPEN Abstract We present an efficient and accurate variant of the conjugate gradient method for solving families of shifted
A parallel scaled conjugate-gradient
Aykanat, Cevdet
. The scaled conjugate- gradient method is a powerful technique for solving large sparse linear systems for form-factor computation. Key words: Gathering radiosity -- Scaled conjugate-gradient method -- Parallel, the Gauss--Jacobi (GJ) method is used in the solution phase. The scaled conjugate-gradient (SCG) method
An Introduction to the Conjugate Gradient Method
An Introduction to the Conjugate Gradient Method Without the Agonizing Pain Jonathan Richard 15213 Abstract The Conjugate Gradient Method is the most prominent iterative method for solving sparse the mumblings of their forebears. Nevertheless, the Conjugate Gradient Method is a composite of simple, elegant
Accurate conjugate gradient methods for shifted systems
Sleijpen, Gerard
Accurate conjugate gradient methods for shifted systems by Jasper van den Eshof and Gerard L. G CONJUGATE GRADIENT METHODS FOR SHIFTED SYSTEMS JASPER VAN DEN ESHOF # AND GERARD L. G. SLEIJPEN # Abstract We present an e#cient and accurate variant of the conjugate gradient method for solving families
Black Holes as Conformal Field Theories on Horizons
Halyo, Edi
2015-01-01T23:59:59.000Z
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.
Primordial black hole evolution in tensor-scalar cosmology
Ted Jacobson
1999-09-06T23:59:59.000Z
A perturbative analysis shows that black holes do not remember the value of the scalar field $\\phi$ at the time they formed if $\\phi$ changes in tensor-scalar cosmology. Moreover, even when the black hole mass in the Einstein frame is approximately unaffected by the changing of $\\phi$, 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.
Black holes in extra dimensions can decay on the bulk
A. K. Chaudhuri
2003-01-08T23:59:59.000Z
In the extra dimensional theories, with TeV scale Plank constant, black holes may be produced in the Large Hadron Collider experiments. We have argued that in the d-dimensional black hole, the intrinsically 4-dimensional brane fields do not see the same geometry at the horizon, as in a 4-dimensional space-time. Kaluza-Klein modes invades the brane and surroundings and the brane fields can be considered as a thermal system at the temperature of the black hole. From energy and entropy consideration, we show that whether or not a six-dimensional black hole will decay by emitting Kaluza-Klein modes or the standard model particles, will depend on the length scale of the extra dimensions as well as on the mass of the black hole. For higher dimensional black holes, Kaluza-Klein modes will dominate the decay.
Scattering of Sound Waves by a Canonical Acoustic Hole
Sam R. Dolan; Ednilton S. Oliveira; Luís C. B. Crispino
2009-04-06T23:59:59.000Z
This is a study of a monochromatic planar perturbation impinging upon a canonical acoustic hole. We show that acoustic hole scattering shares key features with black hole scattering. The interference of wavefronts passing in opposite senses around the hole creates regular oscillations in the scattered intensity. We examine this effect by applying a partial wave method to compute the differential scattering cross section for a range of incident wavelengths. We demonstrate the existence of a scattering peak in the backward direction, known as the glory. We show that the glory created by the canonical acoustic hole is approximately 170 times less intense than the glory created by the Schwarzschild black hole, for equivalent horizon-to-wavelength ratios. We hope that direct experimental observations of such effects may be possible in the near future.
Gradient Navigation Model for Pedestrian Dynamics
Felix Dietrich; Gerta Köster
2014-05-14T23:59:59.000Z
We present a new microscopic ODE-based model for pedestrian dynamics: the Gradient Navigation Model. The model uses a superposition of gradients of distance functions to directly change the direction of the velocity vector. The velocity is then integrated to obtain the location. The approach differs fundamentally from force based models needing only three equations to derive the ODE system, as opposed to four in, e.g., the Social Force Model. Also, as a result, pedestrians are no longer subject to inertia. Several other advantages ensue: Model induced oscillations are avoided completely since no actual forces are present. The derivatives in the equations of motion are smooth and therefore allow the use of fast and accurate high order numerical integrators. At the same time, existence and uniqueness of the solution to the ODE system follow almost directly from the smoothness properties. In addition, we introduce a method to calibrate parameters by theoretical arguments based on empirically validated assumptions rather than by numerical tests. These parameters, combined with the accurate integration, yield simulation results with no collisions of pedestrians. Several empirically observed system phenomena emerge without the need to recalibrate the parameter set for each scenario: obstacle avoidance, lane formation, stop-and-go waves and congestion at bottlenecks. The density evolution in the latter is shown to be quantitatively close to controlled experiments. Likewise, we observe a dependence of the crowd velocity on the local density that compares well with benchmark fundamental diagrams.
Preparation and characterization of gradient polymer films
Smith, S.C.
1987-01-01T23:59:59.000Z
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.
Fontana, Peter R.; Srivastava, Rajendra P.
1973-06-01T23:59:59.000Z
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 ...
Charged Schrodinger black holes
Adams, Allan
We construct charged and rotating asymptotically Schrödinger 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, ...
Helical superconducting black holes
Aristomenis Donos; Jerome P. Gauntlett
2012-05-17T23:59:59.000Z
We construct novel static, asymptotically $AdS_5$ black hole solutions with Bianchi VII$_0$ symmetry that are holographically dual to superconducting phases in four spacetime dimensions with a helical p-wave order. We calculate the precise temperature dependence of the pitch of the helical order. At zero temperature the black holes have vanishing entropy and approach domain wall solutions that reveal homogenous, non-isotropic dual ground states with emergent scaling symmetry.
Turbodrilling in the hot-hole environment
Herbert, P.
1982-10-01T23:59:59.000Z
Historically, geothermal and other types of hot-hole drilling have presented what seemed to be insurmountable barriers to efficient and extended use of downhole drilling motors, particularly those containing elastomeric bearing or motor components. Typical temperatures of 350 to 700/sup 0/F (177 to 371/sup 0/C) damage the elastomers and create other operating problems, reducing the life of the motors and their ability to drill efficiently. Recent innovations in turbodrill design have opened heretofore unrealized potentials and have allowed, for the first time, extended downhole drilling time in hot-hole conditions. The unique feature of this turbodrill is the lack of any elastomers or other temperature-sensitive materials. Its capabilities are matched closely to the requirements of drilling in elevated-temperature environments. The bearing assembly can withstand conditions encountered in typical geothermal formations and provides the performance necessary to stay in the hole. The result is increased rate of penetration (ROP) and more economical drilling.
Paris-Sud XI, UniversitÃ© de
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
BIOGEOCHEMICAL GRADIENTS AS A FRAMEWORK FOR UNDERSTANDING WASTE SITE EVOLUTION
Denham, M; Karen Vangelas, K
2008-10-17T23:59:59.000Z
The migration of biogeochemical gradients is a useful framework for understanding the evolution of biogeochemical conditions in groundwater at waste sites contaminated with metals and radionuclides. This understanding is critical to selecting sustainable remedies and evaluating sites for monitored natural attenuation, because most attenuation mechanisms are sensitive to geochemical conditions such as pH and redox potential. Knowledge of how gradients in these parameters evolve provides insights into the behavior of contaminants with time and guides characterization, remedy selection, and monitoring efforts. An example is a seepage basin site at the Savannah River Site in South Carolina where low-level acidic waste has seeped into groundwater. The remediation of this site relies, in part, on restoring the natural pH of the aquifer by injecting alkaline solutions. The remediation will continue until the pH up-flow of the treatment zone increases to an acceptable value. The time required to achieve this objective depends on the time it takes the trailing pH gradient, the gradient separating the plume from influxing natural groundwater, to reach the treatment zone. Predictions of this length of time will strongly influence long-term remedial decisions.
Ted Jacobson; Gungwon Kang; Robert C. Myers
1994-01-03T23:59:59.000Z
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.}
Gradients of meteorological parameters in convective and nonconvective areas
McCown, Milton Samuel
1976-01-01T23:59:59.000Z
. SYNOPTIC CONDITIONS 4. STRATIFICATION OF DATA 5. COMPUTATIONAL PROCEDURES 21 25 a. Gridding of rawinsonde data 25 b. Gradients 26 5'' lp t* 27 RESULTS 29 a. Gradients 29 1) Convective areas 29 2) Nonconvective areas 31 3) Combined areas 33 vi... air turbulence. By using airplane data from over the western United States, Scoggins (1975) has shown that CAT at 300 mb occurred 71% of the time when the magnitude of the vector horizontal wind shear -5 -1 exceeded 4. 5 x 10 sec . The horizontal...
Shape reconstruction from gradient data
Ettl, Svenja; Kaminski, Juergen; Knauer, Markus C.; Haeusler, Gerd
2008-04-20T23:59:59.000Z
We present a generalized method for reconstructing the shape of an object from measured gradient data. A certain class of optical sensors does not measure the shape of an object but rather its local slope. These sensors display several advantages, including high information efficiency, sensitivity, and robustness. For many applications, however, it is necessary to acquire the shape, which must be calculated from the slopes by numerical integration. Existing integration techniques show drawbacks that render them unusable in many cases. Our method is based on an approximation employing radial basis functions. It can be applied to irregularly sampled, noisy, and incomplete data, and it reconstructs surfaces both locally and globally with high accuracy.
High gradient lens for charged particle beam
Chen, Yu-Jiuan
2014-04-29T23:59:59.000Z
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.
Schwarzschild black hole in dark energy background
Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh
2014-09-27T23:59:59.000Z
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.
Extremal limits and black hole entropy
Sean M. Carroll; Matthew C. Johnson; Lisa Randall
2009-01-08T23:59:59.000Z
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.
Investigating Dark Energy with Black Hole Binaries
Laura Mersini-Houghton; Adam Kelleher
2009-06-08T23:59:59.000Z
The accelerated expansion of the universe is ascribed to the existence of dark energy. Black holes accretion of dark energy induces a mass change proportional to the energy density and pressure of the background dark energy fluid. The time scale during which the mass of black holes changes considerably is too long relative to the age of the universe, thus beyond detection possibilities. We propose to take advantage of the modified black hole masses for exploring the equation of state $w[z]$ of dark energy, by investigating the evolution of supermassive black hole binaries on a dark energy background. Deriving the signatures of dark energy accretion on the evolution of binaries, we find that dark energy imprints on the emitted gravitational radiation and on the changes in the orbital radius of the binary can be within detection limits for certain supermassive black hole binaries. In this talk I describe how binaries can provide a useful tool in obtaining complementary information on the nature of dark energy, based on the work done with A.Kelleher.
Compensated geothermal gradient: new map of old data
Ibrahim, M.W.
1986-05-01T23:59:59.000Z
Bottom-hole temperature measurement is one of the oldest forms of downhole information acquired by the oil industry. Old and new geothermal maps that are based on these measurements have invariably been drawn with an assumed constant or average ground surface temperature over the mapped areas. However, near ground-surface equilibrium temperature is a variable rather than a constant over any region; therefore, old and current geothermal gradient mapping methods give a false impression of the true thermal level of subsurface strata, and may lead to erroneous results of temperature-based calculations, such as the TTI. In this paper, a geothermal mapping method is presented in which extrapolated surface temperature is coupled with the corresponding geothermal gradient over the mapped area. The method was tested on areas in the Middle East and Africa. Results indicate that it is especially effective in delineating loci of vertical geothermal heat flux carried upwards by ascending subsurface fluids; such areas are preferential sites for hydrocarbon entrapment, especially in young sedimentary basins where migration is still in progress.
Webber, Bryan R
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...
Optimization Online - A Nonlinear Conjugate Gradient Algorithm ...
Yu-Hong Dai
2011-06-28T23:59:59.000Z
Jun 28, 2011 ... Abstract: In this paper, we seek the conjugate gradient direction closest to the direction of the scaled memoryless BFGS method and propose a ...
A GLOBALLY CONVERGENT MODIFIED CONJUGATE-GRADIENT ...
2009-10-01T23:59:59.000Z
based upon applying modified variants of either PCG or Lanczos method to the sys- ... conjugate-gradient based strategies for optimizing a constrained ...
Optimization Online - An Accelerated Proximal Coordinate Gradient ...
Qihang Lin
2014-07-07T23:59:59.000Z
Jul 7, 2014 ... An Accelerated Proximal Coordinate Gradient Method and its Application to Regularized Empirical Risk Minimization. Qihang Lin(qihang-lin ...
Optimization of synchronization in gradient clustered networks
Xingang Wang; Liang Huang; Ying-Cheng Lai; Choy Heng Lai
2007-11-23T23:59:59.000Z
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.
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
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.
Black Hole Thermodynamics Today
Ted Jacobson
1998-01-07T23:59:59.000Z
A brief survey of the major themes and developments of black hole thermodynamics in the 1990's is given, followed by summaries of the talks on this subject at MG8 together with a bit of commentary, and closing with a look towards the future.
M. B. Altaie
2001-05-07T23:59:59.000Z
In this paper we follow a new approach for particle creation by a localized strong gravitational field. The approach is based on a definition of the physical vacuum drawn from Heisenberg uncertainty principle. Using the fact that the gravitational field red-shifts the frequency modes of the vacuum, a condition on the minimum stregth of the gravitational field required to achieve real particle creation is derived. Application of this requirement on a Schwartzchid black hole resulted in deducing an upper limit on the region, outside the event horizon, where real particles can be created. Using this regional upper limit, and considering particle creation by black holes as a consequence of the Casimir effect, with the assumption that the created quanta are to be added to the initial energy, we deduce a natural power law for the development of the event horizon, and consequently a logarithmic law for the area spectrum of an inflating black hole. Application of the results on a cosmological model shows that if we start with a Planck-dimensional black hole, then through the process of particle creation we end up with a universe having the presently estimated critical density. Such a universe will be in a state of eternal inflation.
A Mechanism for Coronal Hole Jets
D. A. N. Mueller; S. K. Antiochos
2008-04-24T23:59:59.000Z
Bald patches are magnetic topologies in which the magnetic field is concave up over part of a photospheric polarity inversion line. A bald patch topology is believed to be the essential ingredient for filament channels and is often found in extrapolations of the observed photospheric field. Using an analytic source-surface model to calculate the magnetic topology of a small bipolar region embedded in a global magnetic dipole field, we demonstrate that although common in closed-field regions close to the solar equator, bald patches are unlikely to occur in the open-field topology of a coronal hole. Our results give rise to the following question: What happens to a bald patch topology when the surrounding field lines open up? This would be the case when a bald patch moves into a coronal hole, or when a coronal hole forms in an area that encompasses a bald patch. Our magnetostatic models show that, in this case, the bald patch topology almost invariably transforms into a null point topology with a spine and a fan. We argue that the time-dependent evolution of this scenario will be very dynamic since the change from a bald patch to null point topology cannot occur via a simple ideal evolution in the corona. We discuss the implications of these findings for recent Hinode XRT observations of coronal hole jets and give an outline of planned time-dependent 3D MHD simulations to fully assess this scenario.
Approximate error conjugation gradient minimization methods
Kallman, Jeffrey S
2013-05-21T23:59:59.000Z
In one embodiment, a method includes selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, calculating an approximate error using the subset of rays, and calculating a minimum in a conjugate gradient direction based on the approximate error. In another embodiment, a system includes a processor for executing logic, logic for selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, logic for calculating an approximate error using the subset of rays, and logic for calculating a minimum in a conjugate gradient direction based on the approximate error. In other embodiments, computer program products, methods, and systems are described capable of using approximate error in constrained conjugate gradient minimization problems.
Novel geometry gradient coils for MRI designed by genetic algorithm
Williams, Guy Barnett
2001-06-19T23:59:59.000Z
in the Steady State High Performance Computing Facility Herchel Smith Laboratory for Medicinal Chemistry Message Passing Interface Magnetic Resonance Imaging Positron Emission Tomography Radio frequency Electro-motive force Root mean squared IX & x... by the intro duction of high performance computing. One of the major disadvantages of this approach . to gradient design is the amount of time taken to produce results, and high performance computing has the potential to reduce this. The amount by which a...
BLACK HOLE AURORA POWERED BY A ROTATING BLACK HOLE
Takahashi, Masaaki [Department of Physics and Astronomy, Aichi University of Education, Kariya, Aichi 448-8542 (Japan); Takahashi, Rohta, E-mail: takahasi@phyas.aichi-edu.ac.j [Cosmic Radiation Laboratory, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
2010-05-15T23:59:59.000Z
We present a model for high-energy emission sources generated by a standing magnetohydrodynamical (MHD) shock in a black hole magnetosphere. The black hole magnetosphere would be constructed around a black hole with an accretion disk, where a global magnetic field could be originated by currents in the accretion disk and its corona. Such a black hole magnetosphere may be considered as a model for the central engine of active galactic nuclei, some compact X-ray sources, and gamma-ray bursts. The energy sources of the emission from the magnetosphere are the gravitational and electromagnetic energies of magnetized accreting matters and the rotational energy of a rotating black hole. When the MHD shock generates in MHD accretion flows onto the black hole, the plasma's kinetic energy and the black hole's rotational energy can convert to radiative energy. In this Letter, we demonstrate the huge energy output at the shock front by showing negative energy postshock accreting MHD flows for a rapidly rotating black hole. This means that the extracted energy from the black hole can convert to the radiative energy at the MHD shock front. When an axisymmetric shock front is formed, we expect a ring-shaped region with very hot plasma near the black hole; this would look like an 'aurora'. The high-energy radiation generated from there would carry to us the information for the curved spacetime due to the strong gravity.
Fulvio Melia
2007-05-10T23:59:59.000Z
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.
Clement, María E Gabach
2015-01-01T23:59:59.000Z
It is well known that celestial bodies tend to be spherical due to gravity and that rotation produces deviations from this sphericity. We discuss what is known and expected about the shape of black holes' horizons from their formation to their final, stationary state. We present some recent results showing that black hole rotation indeed manifests in the widening of their central regions, limits their global shapes and enforces their whole geometry to be close to the extreme Kerr horizon geometry at almost maximal rotation speed. The results depend only on the horizon area and angular momentum. In particular they are entirely independent of the surrounding geometry of the spacetime and of the presence of matter satisfying the strong energy condition. We also discuss the the relation of this result with the Hoop conjecture.
The ISO Galactic Metallicity Gradient Revisited
Uriel Giveon; Christophe Morisset; Amiel Sternberg
2002-07-22T23:59:59.000Z
Two independent groups (Giveon et al. 2002; Martin-Hernandez et al. 2002) have recently investigated the Galactic metallicity gradient as probed by ISO observations of mid-infrared emission lines from HII regions. We show that the different gradients inferred by the two groups are due to differing source selection and differing extinction corrections. We show that both data sets in fact provide consistent results if identical assumptions are made in the analysis. We present a consistent set of gradients in which we account for extinction and variation in electron temperature across the disk.
Black hole evolution: I. Supernova-regulated black hole growth
Dubois, Yohan; Silk, Joseph; Devriendt, Julien; Slyz, Adrianne; Teyssier, Romain
2015-01-01T23:59:59.000Z
The growth of a supermassive black hole (BH) is determined by how much gas the host galaxy is able to feed it, which in turn is controlled by the cosmic environment, through galaxy mergers and accretion of cosmic flows that time how galaxies obtain their gas, but also by internal processes in the galaxy, such as star formation and feedback from stars and the BH itself. In this paper, we study the growth of a 10^12 Msun halo at z=2, which is the progenitor of an archetypical group of galaxies at z=0, and of its central BH by means of a high-resolution zoomed cosmological simulation, the Seth simulation. We study the evolution of the BH driven by the accretion of cold gas in the galaxy, and explore the efficiency of the feedback from supernovae (SNe). For a relatively inefficient energy input from SNe, the BH grows at the Eddington rate from early times, and reaches self-regulation once it is massive enough. We find that at early cosmic times z>3.5, efficient feedback from SNe forbids the formation of a settled...
Embeddings of the black holes in a flat space
A. A. Sheykin; D. A. Grad; S. A. Paston
2014-01-30T23:59:59.000Z
We study the explicit embeddings of static black holes. We obtain two new minimal embeddings of the Schwarzchild-de Sitter metric which smoothly cover both horizons of this metric. The lines of time for these embeddings are more complicated than hyperbolas. Also we shortly discuss the possibility of using non-hyperbolic embeddings for calculation of the black hole Hawking temperature in the Deser and Levin approach.
Electromagnetic wave scattering by Schwarzschild black holes
Luís C. B. Crispino; Sam R. Dolan; Ednilton S. Oliveira
2009-05-20T23:59:59.000Z
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.
THE MULTIGRID PRECONDITIONED CONJUGATE GRADIENT METHOD Osamu Tatebe
THE MULTIGRID PRECONDITIONED CONJUGATE GRADIENT METHOD Osamu Tatebe Department of Information Science University of Tokyo Tokyo, JAPAN SUMMARY A multigrid preconditioned conjugate gradient method iterations and the multigrid preconditioner is a desirable preconditioner of the conjugate gradient method. 1
Black holes in massive gravity
Babichev, Eugeny
2015-01-01T23:59:59.000Z
We review the black hole solutions of the ghost-free massive gravity theory and its bimetric extension and outline the main results on the stability of these solutions against small perturbations. Massive (bi)-gravity accommodates exact black hole solutions, analogous to those of General Relativity. In addition to these solutions, hairy black holes -- solutions with no correspondent in General Relativity -- have been found numerically, whose existence is a natural consequence of the absence of the Birkhoff's theorem in these theories. The existence of extra propagating degrees of freedom, makes the stability properties of these black holes richer and more complex than those of General Relativity. In particular, the bi-Schwarzschild black hole exhibits an unstable spherically symmetric mode, while the bi-Kerr geometry is also generically unstable, both against the spherical mode and against superradiant instabilities. If astrophysical black holes are described by these solutions, the superradiant instability o...
Gia Dvali; Cesar Gomez
2012-03-29T23:59:59.000Z
According to the standard view classically black holes carry no hair, whereas quantum hair is at best exponentially weak. We show that suppression of hair is an artifact of the semi-classical treatment and that in the quantum picture hair appears as an inverse mass-square effect. Such hair is predicted in the microscopic quantum description in which a black hole represents a self-sustained leaky Bose-condensate of N soft gravitons. In this picture the Hawking radiation is the quantum depletion of the condensate. Within this picture we show that quantum black hole physics is fully compatible with continuous global symmetries and that global hair appears with the strength B/N, where B is the global charge swallowed by the black hole. For large charge this hair has dramatic effect on black hole dynamics. Our findings can have interesting astrophysical consequences, such as existence of black holes with large detectable baryonic and leptonic numbers.
Separation of carbon nanotubes in density gradients
Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)
2012-02-07T23:59:59.000Z
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.
Separation of carbon nanotubes in density gradients
Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)
2010-02-16T23:59:59.000Z
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.
Ballistic dispersion in temperature gradient focusing
Santiago, Juan G.
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
Light Loop Echoes and Blinking Black Holes
Boyle, Latham
2011-01-01T23:59:59.000Z
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
Observational Evidence for Black Holes
Ramesh Narayan; Jeffrey E. McClintock
2014-07-20T23:59:59.000Z
Astronomers have discovered two populations of black holes: (i) stellar-mass black holes with masses in the range 5 to 30 solar masses, millions of which are present in each galaxy in the universe, and (ii) supermassive black holes with masses in the range 10^6 to 10^{10} solar masses, one each in the nucleus of every galaxy. There is strong circumstantial evidence that all these objects are true black holes with event horizons. The measured masses of supermassive black hole are strongly correlated with properties of their host galaxies, suggesting that these black holes, although extremely small in size, have a strong influence on the formation and evolution of entire galaxies. Spin parameters have recently been measured for a handful of black holes. Based on the data, there is an indication that the kinetic power of at least one class of relativistic jet ejected from accreting black holes may be correlated with black hole spin. If verified, it would suggest that these jets are powered by a generalized Penrose process mediated by magnetic fields.
A globally convergent modified conjugate-gradient line-search ...
Wenwen Zhou
2009-09-23T23:59:59.000Z
Sep 23, 2009 ... Further, we provide a new variant of modified conjugate gradient algorithms ... optimization, trust region methods, conjugate gradient method.
Conjugate gradient methods based on secant conditions that ...
2011-09-28T23:59:59.000Z
Sep 28, 2011 ... (2001) proposed a conjugate gradient method based on the secant ... Recently, the conjugate gradient method is paid attention to as an ...
An inexact accelerated proximal gradient method for large scale ...
2011-09-09T23:59:59.000Z
projected gradient method, and usually has good practical performance on .... conditioned, the conjugate gradient (CG) method would have great difficulty in ...
On the regularizing behavior of recent gradient methods in the ...
Roberta De Asmundis
2014-06-14T23:59:59.000Z
Jun 14, 2014 ... On the regularizing behavior of recent gradient methods in the ... can be competitive with the Conjugate Gradient (CG) method, since they are ...
a perry descent conjugate gradient method with restricted spectrum ...
2011-05-09T23:59:59.000Z
A new nonlinear conjugate gradient method, based on Perry's ... Key words and phrases. large scale optimization, conjugate gradient method, descent property ...
An efficient gradient method using the Yuan steplength
2014-05-29T23:59:59.000Z
Abstract We propose a new gradient method for quadratic programming, named SDC, .... We note that although the Conjugate Gradient (CG) method is still the ...
Comparative systems biology across an evolutionary gradient within...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
systems biology across an evolutionary gradient within the Shewanella genus . Comparative systems biology across an evolutionary gradient within the Shewanella genus . Abstract: To...
Simulating merging binary black holes with nearly extremal spins
Lovelace, Geoffrey [Center for Radiophysics and Space Research, Cornell University, Ithaca, New York, 14853 (United States); Scheel, Mark A.; Szilagyi, Bela [Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125 (United States)
2011-01-15T23:59:59.000Z
Astrophysically realistic black holes may have spins that are nearly extremal (i.e., close to 1 in dimensionless units). Numerical simulations of binary black holes are important tools both for calibrating analytical templates for gravitational-wave detection and for exploring the nonlinear dynamics of curved spacetime. However, all previous simulations of binary-black-hole inspiral, merger, and ringdown have been limited by an apparently insurmountable barrier: the merging holes' spins could not exceed 0.93, which is still a long way from the maximum possible value in terms of the physical effects of the spin. In this paper, we surpass this limit for the first time, opening the way to explore numerically the behavior of merging, nearly extremal black holes. Specifically, using an improved initial-data method suitable for binary black holes with nearly extremal spins, we simulate the inspiral (through 12.5 orbits), merger and ringdown of two equal-mass black holes with equal spins of magnitude 0.95 antialigned with the orbital angular momentum.
Acoustic white holes in flowing atomic Bose-Einstein condensates
Carlos Mayoral; Alessio Recati; Alessandro Fabbri; Renaud Parentani; Roberto Balbinot; Iacopo Carusotto
2010-09-30T23:59:59.000Z
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.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassive Solar HomePromising Science for1 20115, 2001 MediaBrookhavenBlack Holes at
Optical black holes and solitons
Shawn Westmoreland
2010-12-21T23:59:59.000Z
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.
Entropy of Lovelock Black Holes
Ted Jacobson; Robert C. Myers
1993-05-06T23:59:59.000Z
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.
R. B. Mann
1997-05-06T23:59:59.000Z
I demonstrate that, under certain circumstances, regions of negative energy density can undergo gravitational collapse into a black hole. The resultant exterior black hole spacetimes necessarily have negative mass and non-trivial topology. A full theory of quantum gravity, in which topology-changing processes take place, could give rise to such spacetimes.
Geothermal gradient map of the conterminous United States. Second edition
Kron, A.; Stix, J.
1982-01-01T23:59:59.000Z
The second edition of the Geothermal Gradient Map of the Conterminous United States (Kron and Stix 1982) is described and the changes made since the first edition (Kron and Heiken 1980) are compared. The second edition of the map presents a compilation of over 1700 wells that have been measured for temperature belwo 50 m and whose temperature/depth profiles are linear, or composed of linear segments which reflect changes in the thermal conductivity of the rocks rather than hydrology. The data are displayed at an enlarged scale of 1:2,500,000 and in a new format which shows the location, depth, and gradient of each well in a single color-coded symbol. This edition contains over two times the amount of data shown on the first map and is accompained by a table, listing for each well its location, depth, gradient, heat flow (where available), thermal conductivity (where available), and a reference. Over 200 references have been consulted and are presented with the data.
Statistical Estimates For Channel Flows Driven By A Pressure Gradient
Fabio Ramos; Ricardo Rosa; Roger Temam
2006-12-14T23:59:59.000Z
We present rigorous estimates for some physical quantities related to turbulent and non-turbulent channel flows driven by a uniform pressure gradient. Such results are based on the concept of stationary statistical solution, which is related to the notion of ensemble average for flows in statistical equilibrium. We provide a lower bound estimate for the mean skin friction coefficient and improve on a previous upper bound estimate for the same quantity; both estimates in terms of the Reynolds number. We also present lower and upper bound estimates for the mean rate of energy dissipation, the mean longitudinal velocity (in the direction of the pressure gradient), and the mean kinetic energy. In particular, we obtain an upper bound related to the energy dissipation law, namely that the mean rate of energy dissipation is essentially bounded by a non-dimensional universal constant times the cube of the mean longitudinal velocity over a characteristic macro-scale length. Finally, we investigate the scale-by-scale energy injection due to the pressure gradient, proving an upper bound estimate for the decrease of this energy injection as the scale length decreases.
Solar rotation rate and its gradients during cycle 23
H. M. Antia; Sarbani Basu; S. M. Chitre
2008-05-22T23:59:59.000Z
Available helioseismic data now span almost the entire solar activity cycle 23 making it possible to study solar-cycle related changes of the solar rotation rate in detail. In this paper we study how the solar rotation rate, in particular, the zonal flows change with time. In addition to the zonal flows that show a well known pattern in the solar convection zone, we also study changes in the radial and latitudinal gradients of the rotation rate, particularly in the shear layer that is present in the immediate sub-surface layers of the Sun. In the case of the zonal-flow pattern, we find that the band indicating fast rotating region close to the equator seems to have bifurcated around 2005. Our investigation of the rotation-rate gradients show that the relative variation in the rotation-rate gradients is about 20% or more of their average values, which is much larger than the relative variation in the rotation rate itself. These results can be used to test predictions of various solar dynamo models.
Thermal Gradient Holes At Alum Area (DOE GTP) | Open Energy Information
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Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank & Ross,
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Thermal Gradient Holes At Chena Area (Erkan, Et. Al., 2008) | Open Energy
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Thermal Gradient Holes At Chocolate Mountains Area (Sabin, Et Al., 2010) |
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Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al., 2002) | Open
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Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al., 2004) | Open
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Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski, Et Al., 2002)
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Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski, Et Al., 2004)
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Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Fenton Hill HDR Geothermal Area (Purtymun, Et
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Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Flint Geothermal Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Fort Bidwell Area (Lafleur, Et Al., 2010) | Open
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Thermal Gradient Holes At Fort Bliss Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Hawthorne Area (Sabin, Et Al., 2010) | Open
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Thermal Gradient Holes At Hot Pot Area (DOE GTP) | Open Energy Information
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Thermal Gradient Holes At Kilauea East Rift Area (Quane, Et Al., 2000) |
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Thermal Gradient Holes At Kilauea Summit Area (Keller, Et Al., 1979) | Open
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Thermal Gradient Holes At Lake City Hot Springs Area (Warpinski, Et Al.,
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Thermal Gradient Holes At Lightning Dock Area (Cunniff & Bowers, 2005) |
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Thermal Gradient Holes At Lightning Dock Geothermal Area (Arnold, Et Al.,
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Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff & Bowers,
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Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff, Et Al.,
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Thermal Gradient Holes At Long Valley Caldera Geothermal Area (Sorey, Et
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Thermal Gradient Holes At Mccoy Geothermal Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Mcgee Mountain Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Mt Princeton Hot Springs Geothermal Area (Held &
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Thermal Gradient Holes At Neal Hot Springs Geothermal Area (U.S. Geothermal
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Thermal Gradient Holes At Newberry Caldera Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Nw Basin & Range Region (Pritchett, 2004) | Open
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Thermal Gradient Holes At Obsidian Cliff Area (Hulen, Et Al., 2003) | Open
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Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management, 2009)
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Thermal Gradient Holes At San Emidio Desert Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Silver Peak Area (DOE GTP) | Open Energy
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revisionEnvReviewNonInvasiveExplorationUT-gTaguspark JumpDetective JumpInc., 2010) | Open
Thermal Gradient Holes At Spencer Hot Springs Area (Shevenell, Et Al.,
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Thermal Gradient Holes At Tungsten Mountain Area (Kratt, Et Al., 2008) |
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Thermal Gradient Holes At Tungsten Mountain Area (Shevenell, Et Al., 2008)
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Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit & Blackwell,
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Ch. VII, Temperature, heat flow maps and temperature gradient holes | Open
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Thermal Gradient Holes At Chena Geothermal Area (EERE, 2010) | Open Energy
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl., 1993) |
Thermal Gradient Holes At Chena Geothermal Area (Erkan, Et Al., 2007) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl., 1993) |Open
Thermal Gradient Holes At Chena Geothermal Area (Holdmann, Et Al., 2006) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl., 1993) |OpenOpen
Thermal Gradient Holes At Chocolate Mountains Area (Alm, Et Al., 2010) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl., 1993)
Thermal Gradient Holes At Glass Mountain Area (Cumming And Mackie, 2007) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl., 1993)Open
Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010) | Open
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl., 1993)OpenEnergy
Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) | Open
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Thermal Gradient Holes At Kilauea East Rift Geothermal Area (Thomas, 1986)
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Thermal Gradient Holes At Lightning Dock Area (Warpinski, Et Al., 2004) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,Open Energy|Open
Thermal Gradient Holes At Long Valley Caldera Geothermal Area (Farrar, Et
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,Open
Thermal Gradient Holes At Long Valley Caldera Geothermal Area (Sorey, Et
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,OpenEt Al.,Al.,
Thermal Gradient Holes At North Brawley Geothermal Area (Edmunds & W.,
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,OpenEt
Thermal Gradient Holes At North Brawley Geothermal Area (Matlick & Jayne,
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,OpenEt2008) |
Thermal Gradient Holes At Northern Basin & Range Region (Pritchett, 2004) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump Jump to:InformationTheInformationAl.,OpenEt2008)
Thermal Gradient Holes At Pilgrim Hot Springs Area (DOE GTP) | Open Energy
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Thermal Gradient Holes At Roosevelt Hot Springs Geothermal Area (Ward, Et
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump JumpAl., 1978) | Open Energy Information Date 1978 - 1978
Thermal Gradient Holes At Socorro Mountain Area (Owens, Et Al., 2005) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump JumpAl., 1978) | Open Energy Information Date 1978 -
Thermal Gradient Holes At Twenty-Nine Palms Area (Page, Et Al., 2010) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump JumpAl., 1978) | Open Energy Information Date 1978 -Open
Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010) |
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump JumpAl., 1978) | Open Energy Information Date 1978
Thermal Gradient Holes At Walker-Lane Transitional Zone Region (Pritchett,
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia:FAQ < RAPID Jump to:Seadov Pty LtdSteen,Ltd Jump JumpAl., 1978) | Open Energy Information Date 19782004) |
Helgaker, Trygve
Electric field gradient, generalized Sternheimer shieldings and electric field gradient at the nuclei, the generalized Sternheimer shielding constants and the EFG electric dipole polarizabilities discussed by Egstro¨m and co-workers4 and recently in a more general way by Fowler and co-workers.5
Quasinormal frequencies of the Dirac field in the massless topological black hole
A. Lopez-Ortega
2010-06-25T23:59:59.000Z
Motivated by the recent computations of the quasinormal frequencies of higher dimensional black holes we exactly calculate the quasinormal frequencies of the Dirac field propagating in D-dimensional (D > 4) massless topological black hole. From the exact values of the quasinormal frequencies for the fermion and boson fields we discuss whether the recently proposed bound on the relaxation time of a perturbed thermodynamical system is satisfied in D-dimensional massless topological black hole. Also we study the consequences of these results.
TOWARDS STOCHASTIC CONJUGATE GRADIENT METHODS Nicol N. Schraudolph Thore Graepel
Schraudolph, Nicol N.
TOWARDS STOCHASTIC CONJUGATE GRADIENT METHODS Nicol N. Schraudolph Thore Graepel schraudo of conjugate gradients provides a very effective way to optimize large, deterministic systems by gradient de. Here we explore a number of ways to adopt ideas from conjugate gradient in the stochastic setting
Relationship between gradient and EM steps in latent variable models.
Roweis, Sam
includes random search, standard gradientbased algorithms, line search methods such as conjugate gradient to to first order method operat ing on the gradient of a locally reshaped likelihood function. DirectRelationship between gradient and EM steps in latent variable models. Ruslan Salakhutdinov Sam
11 SOME PROPERTIES OF A NEW CONJUGATE GRADIENT METHOD
Yuan, Ya-xiang
11 SOME PROPERTIES OF A NEW CONJUGATE GRADIENT METHOD Y. H. Dai and Y. Yuan State Key Laboratory@cc.ac.cn Abstract: It is proved that the new conjugate gradient method proposed by Dai and Yuan 5] produces problem minf(x) x 2 Rn (1.1) where f is smooth and its gradient g is available. Conjugate gradient methods
Relationship between gradient and EM steps in latent variable models.
Roweis, Sam
includes random search, standard gradient-based algorithms, line search methods such as conjugate gradient to to first order method operat- ing on the gradient of a locally reshaped likelihood function. DirectRelationship between gradient and EM steps in latent variable models. Ruslan Salakhutdinov Sam
Conjugate gradient algorithms using multiple recursions
Barth, T.; Manteuffel, T.
1996-12-31T23:59:59.000Z
Much is already known about when a conjugate gradient method can be implemented with short recursions for the direction vectors. The work done in 1984 by Faber and Manteuffel gave necessary and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented with a single recursion of a certain form. However, this form does not take into account all possible recursions. This became evident when Jagels and Reichel used an algorithm of Gragg for unitary matrices to demonstrate that the class of matrices for which a practical conjugate gradient algorithm exists can be extended to include unitary and shifted unitary matrices. The implementation uses short double recursions for the direction vectors. This motivates the study of multiple recursion algorithms.
17 GHz High Gradient Accelerator Research
Temkin, Richard J. [MIT] [MIT; Shapiro, Michael A. [MIT] [MIT
2013-07-10T23:59:59.000Z
This is a report on the MIT High Gradient Accelerator Research program which has included: Operation of the 17 GHz, 25 MeV MIT/Haimson Research Corp. electron accelerator at MIT, the highest frequency, stand-alone accelerator in the world; collaboration with members of the US High Gradient Collaboration, including the design and test of novel structures at SLAC at 11.4 GHz; the design, construction and testing of photonic bandgap structures, including metallic and dielectric structures; the investigation of the wakefields in novel structures; and the training of the next generation of graduate students and postdoctoral associates in accelerator physics.
High-pressure liquid chromatographic gradient mixer
Daughton, C.G.; Sakaji, R.H.
1982-09-08T23:59:59.000Z
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.
Short wavelength ion temperature gradient turbulence
Chowdhury, J.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar (India); Brunner, S.; Lapillonne, X.; Villard, L. [CRPP, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Jenko, F. [Max-Planck-Institut fuer Plasmaphysik Boltzmannstr. 2, D-85748 Garching (Germany)
2012-10-15T23:59:59.000Z
The ion temperature gradient (ITG) mode in the high wavenumber regime (k{sub y}{rho}{sub s}>1), referred to as short wavelength ion temperature gradient mode (SWITG) is studied using the nonlinear gyrokinetic electromagnetic code GENE. It is shown that, although the SWITG mode may be linearly more unstable than the standard long wavelength (k{sub y}{rho}{sub s}<1) ITG mode, nonlinearly its contribution to the total thermal ion heat transport is found to be low. We interpret this as resulting from an increased zonal flow shearing effect on the SWITG mode suppression.
Black holes with gravitational hair in higher dimensions
Anabalon, Andres [Departamento de Ciencias Facultad de Artes Liberales, Facultad de Ingenieria y Ciencias, Universidad Adolfo Ibanez, Vina Del Mar (Chile); Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1 D-14476 Golm (Germany); Canfora, Fabrizio [Centro de Estudios Cientificos (CECS), Casilla 1469 Valdivia (Chile); Giacomini, Alex; Oliva, Julio [Instituto de Ciencias Fisicas y Matematicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia (Chile)
2011-10-15T23:59:59.000Z
A new class of vacuum black holes for the most general gravity theory leading to second order field equations in the metric in even dimensions is presented. These space-times are locally anti-de Sitter in the asymptotic region, and are characterized by a continuous parameter that does not enter in the conserve charges, nor it can be reabsorbed by a coordinate transformation: it is therefore a purely gravitational hair. The black holes are constructed as a warped product of a two-dimensional space-time, which resembles the r-t plane of the Banados-Teitelboim-Zanelli black hole, times a warp factor multiplying the metric of a D-2-dimensional Euclidean base manifold, which is restricted by a scalar equation. It is shown that all the Noether charges vanish. Furthermore, this is consistent with the Euclidean action approach: even though the black hole has a finite temperature, both the entropy and the mass vanish. Interesting examples of base manifolds are given in eight dimensions which are products of Thurston geometries, giving then a nontrivial topology to the black hole horizon. The possibility of introducing a torsional hair for these solutions is also discussed.
Black Hole Remnants and the Information Loss Paradox
Pisin Chen; Yen Chin Ong; Dong-han Yeom
2015-01-30T23:59:59.000Z
Forty years after the discovery of Hawking radiation, its exact nature remains elusive. If Hawking radiation does not carry any information out from the ever shrinking black hole, it seems that unitarity is violated once the black hole completely evaporates. On the other hand, attempts to recover information via quantum entanglement lead to the firewall controversy. Amid the confusions, the possibility that black hole evaporation stops with a "remnant" has remained unpopular and is often dismissed due to some "undesired properties" of such an object. Nevertheless, as in any scientific debate, the pros and cons of any proposal must be carefully scrutinized. We fill in the void of the literature by providing a timely review of various types of black hole remnants, and provide some new thoughts regarding the challenges that black hole remnants face in the context of information loss paradox and its latest incarnation, namely the firewall controversy. The importance of understanding the role of curvature singularity is also emphasized, after all there remains a possibility that singularity cannot be cured even by quantum gravity. In this context a black hole remnant conveniently serves as a cosmic censor. We conclude that a remnant remains a possible end state of Hawking evaporation, and if it contains large interior geometry, may help to ameliorate information loss and the firewall paradox. We hope that this will raise some interests in the community to investigate remnants more critically but also more thoroughly.
Non-linear Plasma Wake Growth of Electron Holes
Hutchinson, I H; Zhou, C
2015-01-01T23:59:59.000Z
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...
Universal Microfluidic Gradient Generator Daniel Irimia1
Geba, Dan-Andrei
Universal Microfluidic Gradient Generator Daniel Irimia1 , Dan A Geba2 , Mehmet Toner1 1 Bio, Building 114, 16th St, Charlestown, MA 02129. Email: mtoner@hms.harvard.edu Keywords: microfluidics cells in vitro. While microfluidic devices have shown unmatched capability in generating linear stable
Multi-gradient drilling method and system
Maurer, William C. (Houston, TX); Medley, Jr., George H. (Spring, TX); McDonald, William J. (Houston, TX)
2003-01-01T23:59:59.000Z
A multi-gradient system for drilling a well bore from a surface location into a seabed includes an injector for injecting buoyant substantially incompressible articles into a column of drilling fluid associated with the well bore. Preferably, the substantially incompressible articles comprises hollow substantially spherical bodies.
Joining of Tungsten Armor Using Functional Gradients
John Scott O'Dell
2006-12-31T23:59:59.000Z
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.
Photopolymerization in Microfluidic Gradient Generators: Microscale
-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
Alternate Explosions: Collapse and Accretion Events with Red Holes instead of Black Holes
James S. Graber
1999-08-10T23:59:59.000Z
A red hole is "just like a black hole" except it lacks an event horizon and a singularity. As a result, a red hole emits much more energy than a black hole during a collapse or accretion event. We consider how a red hole solution can solve the "energy crisis" and power extremely energetic gamma ray bursts and hypernovae.
Thermodynamics of regular black hole
Yun Soo Myung; Yong-Wan Kim; Young-Jai Park
2008-09-21T23:59:59.000Z
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.
Probing the Spacetime Around Supermassive Black Holes with Ejected Plasma Blobs
Christian, Pierre
2015-01-01T23:59:59.000Z
Millimeter-wavelength VLBI observations of the supermassive black holes in Sgr A* and M87 by the Event Horizon Telescope could potentially trace the dynamics of ejected plasma blobs in real time. We demonstrate that the trajectory and tidal stretching of these blobs can be used to test general relativity and set new constraints on the mass and spin of these black holes.
Density matrix of black hole radiation
Lasma Alberte; Ram Brustein; Andrei Khmelnitsky; A. J. M. Medved
2015-02-09T23:59:59.000Z
Hawking's model of black hole evaporation is not unitary and leads to a mixed density matrix for the emitted radiation, while the Page model describes a unitary evaporation process in which the density matrix evolves from an almost thermal state to a pure state. We compare a recently proposed model of semiclassical black hole evaporation to the two established models. In particular, we study the density matrix of the outgoing radiation and determine how the magnitude of the off-diagonal corrections differs for the three frameworks. For Hawking's model, we find power-law corrections to the two-point functions that induce exponentially suppressed corrections to the off-diagonal elements of the full density matrix. This verifies that the Hawking result is correct to all orders in perturbation theory and also allows one to express the full density matrix in terms of the single-particle density matrix. We then consider the semiclassical theory for which the corrections, being non-perturbative from an effective field-theory perspective, are much less suppressed and grow monotonically in time. In this case, the R\\'enyi entropy for the outgoing radiation is shown to grow linearly at early times; but this growth slows down and the entropy eventually starts to decrease at the Page time. In addition to comparing models, we emphasize the distinction between the state of the radiation emitted from a black hole, which is highly quantum, and that of the radiation emitted from a typical classical black body at the same temperature.
Non-preconditioned conjugate gradient on cell and FPCA-based hybrid supercomputer nodes
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
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.
Non-preconditioned conjugate gradient on cell and FPGA based hybrid supercomputer nodes
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
2009-01-01T23:59:59.000Z
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{sup TM} in conjunction with x86 Opteron{sup TM} 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.
A. Brotas
2006-09-01T23:59:59.000Z
The coordinate system $(\\bar{x},\\bar{t})$ defined by $r = 2m + K\\bar{x}- c K \\bar{t}$ and $t=\\bar{x}/cK - 1 /cK \\int_{r_a}^r (1- 2m/r + K^2)^{1/2} (1 - 2m/r)^{-1}dr$ allow us to write the Schwarzschild metric in the form: \\[ds^2=c^2 d\\bar{t}^2 + (W^2/K^2 - 2W/K) d\\bar{x}^2 + 2c (1 + W/K) d\\bar{x}d\\bar{t} - r^2 (d\\theta^2 + cos^2\\theta d\\phi^2)\\] with $W=(1 - 2m/r + K^2)^{1/2}$, in which the coefficients' pathologies are moved to $r_K = 2m/(1+K^2)$. This new coordinate system is used to study the entrance into a black hole of a rigid line (a line in which the shock waves propagate with velocity c).
P. Jablonka; J. Gorgas; P. Goudfrooij
2007-07-04T23:59:59.000Z
We present the analysis of the radial gradients of stellar absorption lines in a sample of 32 bulges of edge-on spiral galaxies, spanning nearly the full Hubble sequence (from S0 to Sc types), and a large range of velocity dispersion (from about 60 to 300 km/s). Different diagnostics such as index-index, gradient-gradient diagrams, and simple stellar population models are used to tackle the origin of the variation of the bulge stellar population. We find that the vast majority of bulges show older age, lower metallicity and higher [alpha/Fe] in their outer regions than in their central parts. The radial gradients in [Fe/H] are 2 to 3 times larger than in Log(age). The relation between gradient and bulge velocity dispersion is interpreted as a gradual build up of the gradient mean values and their dispersions from high to low velocity dispersion, rather than a pure correlation. The bulge effective radii and the Hubble type of the parent galaxies seem to play a more minor role in causing the observed spatial distributions. At a given velocity dispersion, bulges and ellipticals share common properties.
Automated apparatus for producing gradient gels
Anderson, Norman L. (Clarendon Hills, IL)
1986-01-01T23:59:59.000Z
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.
Exploration of very high gradient cavities
Grigory Eremeev
2011-07-01T23:59:59.000Z
Several of the 9-cell ILC cavities processed at Jlab within ongoing ILC R&D program have shown interesting behavior at high fields, such as mode mixing and sudden field emission turn-on during quench. Equipped with thermometry and oscillating superleak transducer (OST) system for quench detection, we couple our RF measurements with local dissipation measurements. In this contribution we report on our findings with high gradient SRF cavities.
Fast quantum algorithm for numerical gradient estimation
Stephen P. Jordan
2005-01-02T23:59:59.000Z
Given a blackbox for f, a smooth real scalar function of d real variables, one wants to estimate the gradient of f at a given point with n bits of precision. On a classical computer this requires a minimum of d+1 blackbox queries, whereas on a quantum computer it requires only one query regardless of d. The number of bits of precision to which f must be evaluated matches the classical requirement in the limit of large n.
Charged black holes in expanding Einstein-de Sitter universes
Manuela G. Rodrigues; Vilson T. Zanchin
2015-02-02T23:59:59.000Z
Inspired in a previous work by McClure and Dyer (Classical Quantum Gravity 23, 1971 (2006)), we analyze some solutions of the Einstein-Maxwell equations which were originally written to describe charged black holes in cosmological backgrounds. A detailed analysis of the electromagnetic sources for a sufficiently general metric is performed, and then we focus on deriving the electromagnetic four-current as well as the conserved electric charge of each metric. The charged McVittie solution is revisited and a brief study of its causal structure is performed, showing that it may represent a charged black hole in an expanding universe, with the black hole horizon being formed at infinite late times. Charged versions of solutions originally put forward by Vaidya (Vd) and Sultana and Dyer (SD) are also analyzed. It is shown that the charged Sultana-Dyer metric requires a global electric current, besides a central (pointlike) electric charge. With the aim of comparing to the charged McVittie metric, new charged solutions of Vd and SD type are considered. In these cases, the original mass and charge parameters are replaced by particular functions of the cosmological time. In the new generalized charged Vaidya metric the black hole horizon never forms, whereas in the new generalized Sultana-Dyer case both the Cauchy and the black hole horizons develop at infinite late times. A charged version of the Thakurta metric is also studied here. It is also a new solution. As in the charged Sultana-Dyer case, the natural source of the electromagnetic field is a central electric charge with an additional global electric current. The global structure is briefly studied and it is verified that the corresponding spacetime may represent a charged black hole in a cosmological background. All the solutions present initial singularities as found in the McVittie metric.
Comment on "Formation of Holes in Alkanethiol Monolayers on Gold"
Myrick, Michael Lenn
microscopy (STM) images of al- kanethiolate monolayers on gold, one type of defect appears which does concentration.1 Fifth, the evolution of the holes appears to cease once the self-assembled monolayer (SAM) has the surface. They are not usually found very near existing step defects, and time-resolved STM images
Reissner-Nordstrom black hole in dark energy background
Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh
2014-11-29T23:59:59.000Z
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.
Energy Gradient Theory of Hydrodynamic Instability
Hua-Shu Dou
2005-01-28T23:59:59.000Z
A new universal theory for flow instability and turbulent transition is proposed in this study. Flow instability and turbulence transition have been challenging subjects for fluid dynamics for a century. The critical condition of turbulent transition from theory and experiments differs largely from each other for Poiseuille flows. In this paper, a new mechanism of flow instability and turbulence transition is presented for parallel shear flows and the energy gradient theory of hydrodynamic instability is proposed. It is stated that the total energy gradient in the transverse direction and that in the streamwise direction of the main flow dominate the disturbance amplification or decay. A new dimensionless parameter K for characterizing flow instability is proposed for wall bounded shear flows, which is expressed as the ratio of the energy gradients in the two directions. It is thought that flow instability should first occur at the position of Kmax which may be the most dangerous position. This speculation is confirmed by Nishioka et al's experimental data. Comparison with experimental data for plane Poiseuille flow and pipe Poiseuille flow indicates that the proposed idea is really valid. It is found that the turbulence transition takes place at a critical value of Kmax of about 385 for both plane Poiseuille flow and pipe Poiseuille flow, below which no turbulence will occur regardless the disturbance. More studies show that the theory is also valid for plane Couette flows and Taylor-Couette flows between concentric rotating cylinders.
A Preconditioner for a Primal-Dual Newton Conjugate Gradients ...
Kimon Fountoulakis
2014-12-30T23:59:59.000Z
Dec 30, 2014 ... A Preconditioner for a Primal-Dual Newton Conjugate Gradients Method for Compressed Sensing Problems.
Optimization Online - Conjugate gradient methods based on secant ...
Y Narushima
2011-09-28T23:59:59.000Z
Sep 28, 2011 ... Conjugate gradient methods based on secant conditions that generate descent search directions for unconstrained optimization.
A three-term conjugate gradient method with sufficient descent ...
2009-11-02T23:59:59.000Z
Finally, some numerical results of the proposed method are given. keyword; Unconstrained optimization, three-term conjugate gradient method, sufficient.
Feedback Limits Rapid Growth of Seed Black Holes at High Redshift
J. -M. Wang; Y. -M. Chen; C. Hu
2005-12-17T23:59:59.000Z
Seed black holes formed in the collapse of population III stars have been invoked to explain the presence of supermassive black holes at high redshift. It has been suggested that a seed black hole can grow up to $10^{5\\sim 6}\\sunm$ through highly super-Eddington accretion for a period of $\\sim 10^{6\\sim 7}$ yr between redshift $z=20\\sim 24$. We studied the feedback of radiation pressure, Compton heating and outflow during the seed black hole growth. It is found that its surrounding medium fueled to the seed hole is greatly heated by Compton heating. For a super-critical accretion onto a $10^3\\sunm$ seed hole, a Compton sphere (with a temperature $\\sim 10^6$K) forms in a timescale of $1.6\\times 10^3$yr so that the hole is only supplied by a rate of $10^{-3}$ Eddington limit from the Compton sphere. Beyond the Compton sphere, the kinetic feedback of the strong outflow heats the medium at large distance, this leads to a dramatical decrease of the outer Bondi accretion onto the black hole and avoid the accumulation of the matter. The highly super-critical accretion will be rapidly halted by the strong feedback. The seed black holes hardly grow up at the very early universe unless the strong feedback can be avoided.
Isolated Horizons: A Generalization of Black Hole Mechanics
Abhay Ashtekar; Christopher Beetle; Stephen Fairhurst
1998-12-18T23:59:59.000Z
A set of boundary conditions defining a non-rotating isolated horizon are given in Einstein-Maxwell theory. A space-time representing a black hole which itself is in equilibrium but whose exterior contains radiation admits such a horizon . Physically motivated, (quasi-)local definitions of the mass and surface gravity of an isolated horizon are introduced. Although these definitions do not refer to infinity, the quantities assume their standard values in Reissner-Nordstrom solutions. Finally, using these definitions, the zeroth and first laws of black hole mechanics are established for isolated horizons.
Construction of a Penrose Diagram for an Accreting Black Hole
Beth A. Brown; James Lindesay
2008-11-04T23:59:59.000Z
A Penrose diagram is constructed for a spatially coherent black hole that accretes at stepwise steady rates as measured by a distant observer from an initial state described by a metric of Minkowski form. Coordinate lines are computationally derived, and radial light-like trajectories verify the viability of the diagram. Coordinate dependencies of significant features, such as the horizon and radial mass scale, are clearly demonstrated on the diagram. The onset of a singularity at the origin is shown to open a new region in space-time that contains the interior of the black hole.
Energy Associated with Schwarzschild Black Hole in a Magnetic Universe
S. S. Xulu
2000-01-29T23:59:59.000Z
In this paper we obtain the energy distribution associated with the Ernst space-time (geometry describing Schwarzschild black hole in Melvin's magnetic universe) in Einstein's prescription. The first term is the rest-mass energy of the Schwarzschild black hole, the second term is the classical value for the energy of the uniform magnetic field and the remaining terms in the expression are due to the general relativistic effect. The presence of the magnetic field is found to increase the energy of the system.
AN EXTENDED CLASS OF NONLINEAR CONJUGATE GRADIENT METHODS \\Lambda
Yuan, Ya-xiang
AN EXTENDED CLASS OF NONLINEAR CONJUGATE GRADIENT METHODS \\Lambda Y. H. Dai and Y. Yuan State Key 100080, P. R. China. Email: dyh,yyx@lsec.cc.ac.cn Abstract Conjugate gradient methods are very important be analyzed uniformly, conjugate gradient methods are often analyzed individually. Recently, Dai and Yuan
AN AUGMENTED CONJUGATE GRADIENT METHOD FOR SOLVING CONSECUTIVE
Paris-Sud XI, Université de
AN AUGMENTED CONJUGATE GRADIENT METHOD FOR SOLVING CONSECUTIVE SYMMETRIC POSITIVE DEFINITE LINEAR definite matrix A. The conjugate gradient method applied to the first system generates a Krylov subspace conjugate gradient method is then applied with a specific initial guess and initial descent direction
CONVERGENCE PROPERTIES OF NONLINEAR CONJUGATE GRADIENT METHODS1
Yuan, Ya-xiang
CONVERGENCE PROPERTIES OF NONLINEAR CONJUGATE GRADIENT METHODS1 Yuhong Dai2 , Jiye Han3 , Guanghui contributions on convergence studies of conjugate gradient methods have been made by Gilbert and Nocedal [6 for ensuring the global convergence of conjugate gradient methods. This paper shows that the sufficient descent
ON THE CONNECTION BETWEEN THE CONJUGATE GRADIENT METHOD AND
Forsgren, Anders
ON THE CONNECTION BETWEEN THE CONJUGATE GRADIENT METHOD AND QUASI-NEWTON METHODS ON QUADRATIC Royal Institute of Technology February 2013 Abstract It is well known that the conjugate gradient method gradient method. In the framework based on a sufficient condition to obtain mutually conjugate search
Preconditioned Conjugate Gradient Methods for Three Dimensional Linear Elasticity
Waterloo, University of
Preconditioned Conjugate Gradient Methods for Three Dimensional Linear Elasticity by John Kenneth. A brief review is also made of stopping criteria for conjugate gradient solvers. One method based and tested with poor results. iv #12;Contents 1 Introduction 1 1.1 Preconditioned Conjugate Gradient Methods
CG DESCENT, A CONJUGATE GRADIENT METHOD WITH GUARANTEED DESCENT
Zhang, Hongchao
CG DESCENT, A CONJUGATE GRADIENT METHOD WITH GUARANTEED DESCENT #3; WILLIAM W. HAGER y AND HONGCHAO are given. Key words. Conjugate gradient method, unconstrained optimization, convergence, line search, Wolfe nonlinear conjugate gradient method for solving an unconstrained optimization problem min ff(x) : x 2
Exploiting Matrix Symmetry to Improve FPGA-Accelerated Conjugate Gradient
Bakos, Jason D.
the Conjugate Gradient (CG) method using an FPGA co-processor. As in previous approaches, our coExploiting Matrix Symmetry to Improve FPGA- Accelerated Conjugate Gradient Jason D. Bakos, Krishna, high- performance computing, sparse matrix vector multiply, conjugate gradient I. INTRODUCTION Linear
A conjugate gradient learning algorithm for recurrent neural networks
Mak, Man-Wai
]. In particular, the conjugate gradient method is commonly used in training BP networks due to its speed1 A conjugate gradient learning algorithm for recurrent neural networks (Revised Version) Wing algorithm by incorporating conjugate gradient computation into its learning procedure. The resulting
APPROXIMATE INVERSE PRECONDITIONING FOR THE CONJUGATE GRADIENT METHOD
Tùma, Miroslav
APPROXIMATE INVERSE PRECONDITIONING FOR THE CONJUGATE GRADIENT METHOD ON A VECTOR COMPUTER Michele definite matrix, by the preconditioned conjugate gradient method (PCG) (see, e.g., [4]). It is well of the conjugate gradient method reduces to computing a matrix vector product with G, an operation which offers
Gradient-based Methods for Production Optimization of Oil Reservoirs
Foss, Bjarne A.
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
Supercurrent: Vector Hair for an AdS Black Hole
Pallab Basu; Anindya Mukherjee; Hsien-Hang Shieh
2008-09-26T23:59:59.000Z
In arXiv:0803.3295 [hep-th] a holographic black hole solution is discussed which exhibits a superconductor like transition. In the superconducting phase the black holes show infinite DC conductivity. This gives rise to the possibility of deforming the solutions by turning on a time independent current (supercurrent), without any electric field. This type of deformation does not exist for normal (non-superconducting) black holes, due to the no-hair theorems. In this paper we have studied such a supercurrent solution and the associated phase diagram. Interestingly, we have found a "special point" (critical point) in the phase diagram where the second order superconducting phase transition becomes first order. Supercurrent in superconducting materials is a well studied phenomenon in condensed matter systems. We have found some qualitative agreement with known results.
Slant hole completion test (1991) sidetrack ``as built`` report
Myal, F.R.
1992-05-01T23:59:59.000Z
During the summer of 1990, a slant hole test well, funded by the US Department of Energy, was drilled to 9,466 ft to evaluate the effectiveness of directional drilling in the tight, naturally fractured gas sands and coals of the Mesaverde Group. The surface location of the SHCT No. 1 is 700 ft south of the DOE Multiwell Experiment (MWX) site in Section 34, T6S, R94W, Garfield County, Colorado, approximately 7.5 miles west of Rifle. Mechanical problems following cementing of a production liner resulted in loss of the completion interval, and operations were suspended. In early 1991, DOE decided to sidetrack the hole to permit production testing of the lost interval. The sidetrack was designed to parallel the original wellbore, but to be drilled 1,000 ft to the east to minimize the chances of encountering formation damage from the original hole. The sidetrack, like the original hole, was to intersect the paludal lenticular sands and coals at 60{degrees} and to penetrate the underlying Cozzette sand horizonally. The sidetrack was spudded May 12, 1991. After re-entering the well in late 1991, early production testing of the Cozzette showed that the 300 ft of in-pay horizontal hole can produce at rate 5 to 10 times higher than vertical wells in the same area. This report contains the geological summary and sidetrack drilling operations summary.
Slant hole completion test (1991) sidetrack as built'' report
Myal, F.R.
1992-05-01T23:59:59.000Z
During the summer of 1990, a slant hole test well, funded by the US Department of Energy, was drilled to 9,466 ft to evaluate the effectiveness of directional drilling in the tight, naturally fractured gas sands and coals of the Mesaverde Group. The surface location of the SHCT No. 1 is 700 ft south of the DOE Multiwell Experiment (MWX) site in Section 34, T6S, R94W, Garfield County, Colorado, approximately 7.5 miles west of Rifle. Mechanical problems following cementing of a production liner resulted in loss of the completion interval, and operations were suspended. In early 1991, DOE decided to sidetrack the hole to permit production testing of the lost interval. The sidetrack was designed to parallel the original wellbore, but to be drilled 1,000 ft to the east to minimize the chances of encountering formation damage from the original hole. The sidetrack, like the original hole, was to intersect the paludal lenticular sands and coals at 60{degrees} and to penetrate the underlying Cozzette sand horizonally. The sidetrack was spudded May 12, 1991. After re-entering the well in late 1991, early production testing of the Cozzette showed that the 300 ft of in-pay horizontal hole can produce at rate 5 to 10 times higher than vertical wells in the same area. This report contains the geological summary and sidetrack drilling operations summary.
Tartakovsky, Daniel M.
Transient effective hydraulic conductivities under slowly and rapidly varying mean gradients it Darcian in real or transformed domains. Each such situation gives rise to an effective hydraulic-time. In this paper we develop first-order analytical expressions for effective hydraulic conductivity under three
RIS-M-2260 HEAT GRADIENT INDUCED MIGRATION OF BRINE INCLUSIONS IN ROCK SALT
RISØ-M-2260 HEAT GRADIENT INDUCED MIGRATION OF BRINE INCLUSIONS IN ROCK SALT Mathematical treatment project. Abstract. A mathematical model for the brine migration in rock salt around an infinite line heat source is set up. The tempera- ture field around the time dependent heat source is calculated by use
A scale-free analysis of magnetic holes in the solar wind
Stevens, M. L. (Michael Louis)
2006-01-01T23:59:59.000Z
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 ...
Measuring the Black Hole Spin in Sgr A*
Fulvio Melia; Benjamin C. Bromley; Siming Liu; Christopher; K. Walker
2001-05-11T23:59:59.000Z
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 min
Entropy: From Black Holes to Ordinary Systems
J. P. Badiali
2005-05-11T23:59:59.000Z
Several results of black holes thermodynamics can be considered as firmly founded and formulated in a very general manner. From this starting point we analyse in which way these results may give us the opportunity to gain a better understanding in the thermodynamics of ordinary systems for which a pre-relativistic description is sufficient. First, we investigated the possibility to introduce an alternative definition of the entropy basically related to a local definition of the order in a spacetime model rather than a counting of microstates. We show that such an alternative approach exists and leads to the traditional results provided an equilibrium condition is assumed. This condition introduces a relation between a time interval and the reverse of the temperature. We show that such a relation extensively used in the black hole theory, mainly as a mathematical trick, has a very general and physical meaning here; in particular its derivation is not related to the existence of a canonical density matrix. Our dynamical approach of thermodynamic equilibrium allows us to establish a relation between action and entropy and we show that an identical relation exists in the case of black holes. The derivation of such a relation seems impossible in the Gibbs ensemble approach of statistical thermodynamics. From these results we suggest that the definition of entropy in terms of order in spacetime should be more general that the Boltzmann one based on a counting of microstates. Finally we point out that these results are obtained by reversing the traditional route going from the Schr\\"{o}dinger equation to statistical thermodynamics.
Horizon dynamics of distorted rotating black holes
Tony Chu; Harald P. Pfeiffer; Michael I. Cohen
2011-04-28T23:59:59.000Z
We present numerical simulations of a Kerr black hole perturbed by a pulse of ingoing gravitational radiation. For strong perturbations we find up to five concentric marginally outer trapped surfaces. These trapped surfaces appear and disappear in pairs, so that the total number of such surfaces at any given time is odd. The world tubes traced out by the marginally outer trapped surfaces are found to be spacelike during the highly dynamical regime, approaching a null hypersurface at early and late times. We analyze the structure of these marginally trapped tubes in the context of the dynamical horizon formalism, computing the expansion of outgoing and incoming null geodesics, as well as evaluating the dynamical horizon flux law and the angular momentum flux law. Finally, we compute the event horizon. The event horizon is well-behaved and approaches the apparent horizon before and after the highly dynamical regime. No new generators enter the event horizon during the simulation.
Hawking Emission and Black Hole Thermodynamics
Don N. Page
2006-12-18T23:59:59.000Z
A brief review of Hawking radiation and black hole thermodynamics is given, based largely upon hep-th/0409024.
On the nature of black hole entropy
Ted Jacobson
2000-01-13T23:59:59.000Z
I argue that black hole entropy counts only those states of a black hole that can influence the outside, and attempt (with only partial success) to defend this claim against various objections, all but one coming from string theory. Implications for the nature of the Bekenstein bound are discussed, and in particular the case for a holographic principle is challenged. Finally, a generalization of black hole thermodynamics to "partial event horizons" in general spacetimes without black holes is proposed.
Quantum Black Hole Formation in the BFSS Matrix Model
Sinya Aoki; Masanori Hanada; Norihiro Iizuka
2015-03-18T23:59:59.000Z
We study the various head-on collisions of two bunches of D0-branes and their real-time evolution in the BFSS matrix model in classical limit. For a various matrix size N respecting the 't Hooft scaling, we find quantitative evidence for the formation of a single bound state of D0-branes at late time, which is matrix model thermalization and dual to the formation of a larger black hole.
High precision, rapid laser hole drilling
Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.
2013-04-02T23:59:59.000Z
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.
Absorption cross section in Lifshitz black hole
Taeyoon Moon; Yun Soo Myung
2012-10-05T23:59:59.000Z
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.
Cruz-Dombriz, A. de la; Dobado, A.; Maroto, A. L. [Departamento de Fisica Teorica I, Universidad Complutense de Madrid, 28040 Madrid (Spain)
2009-12-15T23:59:59.000Z
In the context of f(R) theories of gravity, we address the problem of finding static and spherically symmetric black hole solutions. Several aspects of constant curvature solutions with and without electric charge are discussed. We also study the general case (without imposing constant curvature). Following a perturbative approach around the Einstein-Hilbert action, it is found that only solutions of the Schwarzschild-(anti) de Sitter type are present up to second order in perturbations. Explicit expressions for the effective cosmological constant are obtained in terms of the f(R) function. Finally, we have considered the thermodynamics of black holes in anti-de Sitter space-time and found that this kind of solution can only exist provided the theory satisfies R{sub 0}+f(R{sub 0})<0. Interestingly, this expression is related to the condition which guarantees the positivity of the effective Newton's constant in this type of theories. In addition, it also ensures that the thermodynamical properties in f(R) gravities are qualitatively similar to those of standard general relativity.
Sherman, Tim
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
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
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.
The lifetime problem of evaporating black holes: mutiny or resignation
Carlos Barceló; Raúl Carballo-Rubio; Luis J. Garay; Gil Jannes
2015-02-09T23:59:59.000Z
It is logically possible that regularly evaporating black holes exist in nature. In fact, the prevalent theoretical view is that these are indeed the real objects behind the curtain in astrophysical scenarios. There are several proposals for regularizing the classical singularity of black holes so that their formation and evaporation do not lead to information-loss problems. One characteristic is shared by most of these proposals: these regularly evaporating black holes present long-lived trapping horizons, with absolutely enormous evaporation lifetimes in whatever measure. Guided by the discomfort with these enormous and thus inaccessible lifetimes, we elaborate here on an alternative regularization of the classical singularity, previously proposed by the authors in an emergent gravity framework, which leads to a completely different scenario. In our scheme the collapse of a stellar object would result in a genuine time-symmetric bounce, which in geometrical terms amounts to the connection of a black-hole geometry with a white-hole geometry in a regular manner. The two most differential characteristics of this proposal are: i) the complete bouncing geometry is a solution of standard classical general relativity everywhere except in a transient region that necessarily extends beyond the gravitational radius associated with the total mass of the collapsing object; and ii) the duration of the bounce as seen by external observers is very brief (fractions of milliseconds for neutron-star-like collapses). This scenario motivates the search for new forms of stellar equilibrium different from black holes. In a brief epilogue we compare our proposal with a similar geometrical setting recently proposed by Haggard and Rovelli.
Stability of Horava-Lifshitz Black Holes in the Context of AdS/CFT
Ong, Yen Chin; /Taiwan, Natl. Taiwan U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
2012-06-13T23:59:59.000Z
The anti-de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid, and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Horava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attention due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Horava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Horava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in {lambda} = 1 Horava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter {epsilon} close to unity. Sufficiently charged flat black holes for {epsilon} close to unity, and sufficiently charged positively curved black holes with {epsilon} close to zero, are also unstable. The implication to the Horava-Lifshitz holographic superconductor is discussed.
Black Hole Evaporation as a Nonequilibrium Process
Hiromi Saida
2008-11-11T23:59:59.000Z
When a black hole evaporates, there arises a net energy flow from the black hole into its outside environment due to the Hawking radiation and the energy accretion onto black hole. Exactly speaking, due to the net energy flow, the black hole evaporation is a nonequilibrium process. To study details of evaporation process, nonequilibrium effects of the net energy flow should be taken into account. In this article we simplify the situation so that the Hawking radiation consists of non-self-interacting massless matter fields and also the energy accretion onto the black hole consists of the same fields. Then we find that the nonequilibrium nature of black hole evaporation is described by a nonequilibrium state of that field, and we formulate nonequilibrium thermodynamics of non-self-interacting massless fields. By applying it to black hole evaporation, followings are shown: (1) Nonequilibrium effects of the energy flow tends to accelerate the black hole evaporation, and, consequently, a specific nonequilibrium phenomenon of semi-classical black hole evaporation is suggested. Furthermore a suggestion about the end state of quantum size black hole evaporation is proposed in the context of information loss paradox. (2) Negative heat capacity of black hole is the physical essence of the generalized second law of black hole thermodynamics, and self-entropy production inside the matter around black hole is not necessary to ensure the generalized second law. Furthermore a lower bound for total entropy at the end of black hole evaporation is given. A relation of the lower bound with the so-called covariant entropy bound conjecture is interesting but left as an open issue.
Constant field gradient planar coupled cavity structure
Kang, Y.W.; Kustom, R.L.
1999-07-27T23:59:59.000Z
A cavity structure is disclosed having at least two opposing planar housing members spaced apart to accommodate the passage of a particle beam through the structure between the members. Each of the housing members have a plurality of serially aligned hollows defined therein, and also passages, formed in the members, which interconnect serially adjacent hollows to provide communication between the hollows. The opposing planar housing members are spaced and aligned such that the hollows in one member cooperate with corresponding hollows in the other member to form a plurality of resonant cavities aligned along the particle beam within the cavity structure. To facilitate the obtaining of a constant field gradient within the cavity structure, the passages are configured so as to be incrementally narrower in the direction of travel of the particle beam. In addition, the spacing distance between the opposing housing members is configured to be incrementally smaller in the direction of travel of the beam. 16 figs.
Optimization in the Parikh-Wilczek tunneling model of Hawking radiation for Kerr-Newman Black Holes
Auttakit Chatrabhuti; Khem Upathambhakul
2014-03-17T23:59:59.000Z
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 $Q/M = 1$.
Mass without radiation: heavily obscured AGN, the X-ray Background and the Black Hole Mass Density
Comastri, A; Marconi, A; Risaliti, G; Salvati, M
2015-01-01T23:59:59.000Z
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.
Pinatubo fails to deepen the ozone hole
Kerr, R.A.
1992-10-15T23:59:59.000Z
When the Philippine volcano Pinatubo exploded last year, pumping the upper atmosphere full of find debris, researchers foresaw yet another assault on the stratosphere's beleaguered ozone layer. Some calculations of the effects of volcanic debris implied that as much as 25% to 30% of the ozone shield over temperature latitudes might be eaten away by the volcanic haze - five times the observed loss over the past decade. Early measurements didn't bear out that concern, but researchers weren't prepared to call off the alarm until the verdict came in from the most vulnerable part of the planet's ozone layer, the frigid stratosphere over Antarctica. Although the hole was more extensive than ever before, probably because of unusual weather patterns, total ozone bottomed out well above the record set last year - even a tad above the low levels seen in 1987, 1989, and 1990.
Accelerating and rotating black holes
J. B. Griffiths; J. Podolsky
2005-07-06T23:59:59.000Z
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.
A Nonlinear Conjugate Gradient Algorithm with An Optimal Property ...
2011-06-15T23:59:59.000Z
scaled memoryless BFGS method and propose a family of conjugate gradient methods for unconstrained optimization. An improved Wolfe line search is also ...
Optimization Online - A three-term conjugate gradient method with ...
Y Narushima
2009-12-03T23:59:59.000Z
Dec 3, 2009 ... A three-term conjugate gradient method with sufficient descent property for unconstrained optimization. Y Narushima(narusima ***at*** ...
Optimization Online - Linearizing the Method of Conjugate Gradients
Serge Gratton
2012-09-09T23:59:59.000Z
Sep 9, 2012 ... Abstract: The method of conjugate gradients (CG) is widely used for the iterative solution of large sparse systems of equations $Ax=b$, where ...
A Perry Descent Conjugate Gradient Method with Restricted Spectrum
Dongyi Liu
2011-03-07T23:59:59.000Z
Mar 7, 2011 ... Abstract: A new nonlinear conjugate gradient method, based on Perry's idea, is presented. And it is shown that its sufficient descent property is ...
On the connection between the conjugate gradient method and ...
Anders Forsgren
2013-02-09T23:59:59.000Z
Feb 9, 2013 ... Abstract: It is well known that the conjugate gradient method and a quasi-Newton method, using any well-defined update matrix from the ...
Concentration Gradient and Information Energy for Decentralized UAV Control1
Mohseni, Kamran
spills, industrial release accidents, or chemical/biological/nuclear terrorist attacks. DependingConcentration Gradient and Information Energy for Decentralized UAV Control1 William J. Pisano2
alpine elevation gradient: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Niche expansion leads to small-scale adaptive divergence along an elevation gradient in a medium of the Environment, University of California, Los Angeles, CA 90095, USA Niche...
Photo of the Week: The Alternating Gradient Synchrotron | Department...
Broader source: Energy.gov (indexed) [DOE]
Gradient Synchrotron (AGS) has been one of the world's premiere particle accelerators, well known for the
Spatiotemporal Gradient Modeling with Applications Harrison S. Quick1
Carlin, Bradley P.
, and geospatial information storage, analysis, and distribution systems have led to a burgeoning of spatial 2.3 Gradient analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.5 Data analysis
A Sparsity Preserving Stochastic Gradient Method for Composite ...
Qihang Lin
2011-04-23T23:59:59.000Z
Apr 23, 2011 ... Abstract: We propose new stochastic gradient algorithms for solving convex composite optimization problems. In each iteration, our algorithms ...
A Sparsity Preserving Stochastic Gradient Method for Composite ...
2011-04-23T23:59:59.000Z
Apr 23, 2011 ... We propose new stochastic gradient algorithms for solving convex composite optimization problems. In each iteration, our algorithms utilize a ...
Existence and uniqueness of global classical solutions of a gradient ...
2015-01-22T23:59:59.000Z
This gradient flow is generated by the Laudau-de Gennes energy functional that ... feature of this evolution problem is that it is generated by an energy functional ...
An accelerated proximal gradient algorithm for nuclear norm ...
Kim-Chuan Toh
2009-03-27T23:59:59.000Z
Mar 27, 2009 ... An accelerated proximal gradient algorithm for nuclear norm regularized least squares problems. Kim-Chuan Toh (mattohkc ***at*** nus.edu.sg)
Gradient methods for convex minimization: better rates under ...
Hui Zhang
2013-03-20T23:59:59.000Z
Mar 20, 2013 ... Gradient methods for convex minimization: better rates under weaker conditions. Hui Zhang(hhuuii.zhang ***at*** gmail.com)
Geology and Temperature Gradient Surveys Blue Mountain Geothermal...
Gradient Surveys Blue Mountain Geothermal Discovery, Humboldt County, Nevada Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Geology and...
Down hole periodic seismic generator
Hardee, Harry C. (Albuquerque, NM); Hills, Richard G. (Las Cruces, NM); Striker, Richard P. (Albuquerque, NM)
1989-01-01T23:59:59.000Z
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.
Backdraft: String Creation in an Old Schwarzschild Black Hole
Eva Silverstein
2014-02-21T23:59:59.000Z
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.
BSW process of the slowly evaporating charged black hole
Liancheng Wang; Feng He; Xiangyun Fu
2015-02-09T23:59:59.000Z
In this paper, we study the BSW process of the slowly evaporating charged black hole. It can be found that the BSW process will also arise near black hole horizon when the evaporation of charged black hole is very slow. But now the background black hole does not have to be an extremal black hole, and it will be approximately an extremal black hole unless it is nearly a huge stationary black hole.
Nano-electron beam induced current and hole charge dynamics through uncapped Ge nanocrystals
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
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.
Entanglement entropy of black holes
Sergey N. Solodukhin
2011-04-19T23:59:59.000Z
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.
Quantum Geometry and Black Holes
G., J Fernando Barbero
2015-01-01T23:59:59.000Z
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...
Charged spinning black holes as particle accelerators
Wei Shaowen; Liu Yuxiao; Guo Heng; Fu Chune [Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000 (China)
2010-11-15T23:59:59.000Z
It has recently been pointed out that the spinning Kerr black hole with maximal spin could act as a particle collider with arbitrarily high center-of-mass energy. In this paper, we will extend the result to the charged spinning black hole, the Kerr-Newman black hole. The center-of-mass energy of collision for two uncharged particles falling freely from rest at infinity depends not only on the spin a but also on the charge Q of the black hole. We find that an unlimited center-of-mass energy can be approached with the conditions: (1) the collision takes place at the horizon of an extremal black hole; (2) one of the colliding particles has critical angular momentum; (3) the spin a of the extremal black hole satisfies (1/{radical}(3)){<=}(a/M){<=}1, where M is the mass of the Kerr-Newman black hole. The third condition implies that to obtain an arbitrarily high energy, the extremal Kerr-Newman black hole must have a large value of spin, which is a significant difference between the Kerr and Kerr-Newman black holes. Furthermore, we also show that, for a near-extremal black hole, there always exists a finite upper bound for center-of-mass energy, which decreases with the increase of the charge Q.
Adaptive Event Horizon Tracking and Critical Phenomena in Binary Black Hole Coalescence
Scott A. Caveny; Richard A. Matzner
2003-04-30T23:59:59.000Z
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.
Linking the fate of massive black hole binaries to the active galactic nuclei luminosity function
Dotti, Massimo; Montuori, Carmen
2015-01-01T23:59:59.000Z
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 ...
Chemical aspects of cylinder corrosion and a scenario for hole development
Barber, E.J. [Martin Marietta Energy Systems, Oak Ridge, TN (United States)
1991-12-31T23:59:59.000Z
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.
Entangled valence electron-hole dynamics revealed by stimulated attosecond x-ray Raman scattering
Healion, Daniel; Zhang, Yu; Biggs, Jason D.; Govind, Niranjan; Mukamel, Shaul
2012-09-06T23:59:59.000Z
We show that broadband x-ray pulses can create wavepackets of valence electrons and holes localized in the vicinity of a selected atom (nitrogen, oxygen or sulfur in cysteine) by resonant stimulated Raman scattering. The subsequent dynamics reveals highly correlated motions of entangled electrons and hole quasiparticles. This information goes beyond the time-dependent total charge density derived from x-ray diffraction.
Dirac Quasinormal modes of MSW black holes
Sebastian, Saneesh
2014-01-01T23:59:59.000Z
In this paper we study the Dirac quasinormal modes of an uncharged 2 + 1 black hole proposed by Mandal et. al and referred to as MSW black hole in this work. The quasi- normal mode is studied using WKB approximation method. The study shows that the imaginary part of quasinormal frequencies increases indicating that the oscillations are damping and hence the black hole is stable against Dirac perturbations.
Dirac Quasinormal modes of MSW black holes
Saneesh Sebastian; V. C. Kuriakose
2014-01-15T23:59:59.000Z
In this paper we study the Dirac quasinormal modes of an uncharged 2 + 1 black hole proposed by Mandal et. al and referred to as MSW black hole in this work. The quasi- normal mode is studied using WKB approximation method. The study shows that the imaginary part of quasinormal frequencies increases indicating that the oscillations are damping and hence the black hole is stable against Dirac perturbations.
Black hole entropy: inside or out?
Ted Jacobson; Donald Marolf; Carlo Rovelli
2005-01-14T23:59:59.000Z
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.
Spinning Black Holes as Particle Accelerators
Ted Jacobson; Thomas P. Sotiriou
2010-01-21T23:59:59.000Z
It has recently been pointed out that particles falling freely from rest at infinity outside a Kerr black hole can in principle collide with 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 ultra-energetic collisions cannot occur near black holes in nature.
Probing the Constituent Structure of Black Holes
Lukas Gruending; Stefan Hofmann; Sophia Müller; Tehseen Rug
2014-12-12T23:59:59.000Z
We calculate the cross section for scattering processes between graviton emitters on the near side of a Schwarzschild surface and absorbers on its far side, that is black hole constituents. We show that these scatterings allow to directly extract structural observables such as the momentum distribution of black hole constituents. For this we employ a quantum bound state description originally developed in quantum chromodynamics and recently applied to general relativity that allows to consider black holes in a relativistic Hartree like framework.
Electromagnetic Beams Overpass the Black Hole Horizon
Alexander Burinskii
2008-06-16T23:59:59.000Z
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.
Remarks on Renormalization of Black Hole Entropy
Sang Pyo Kim; Sung Ku Kim; Kwang-Sup Soh; Jae Hyung Yee
1996-07-07T23:59:59.000Z
We elaborate the renormalization process of entropy of a nonextremal and an extremal Reissner-Nordstr\\"{o}m black hole by using the Pauli-Villars regularization method, in which the regulator fields obey either the Bose-Einstein or Fermi-Dirac distribution depending on their spin-statistics. The black hole entropy involves only two renormalization constants. We also discuss the entropy and temperature of the extremal black hole.
Black holes with massive graviton hair
Richard Brito; Vitor Cardoso; Paolo Pani
2013-09-03T23:59:59.000Z
No-hair theorems exclude the existence of nontrivial scalar and massive vector hair outside four-dimensional, static, asymptotically flat black-hole spacetimes. We show, by explicitly building nonlinear solutions, that black holes can support massive graviton hair in theories of massive gravity. These hairy solutions are, most likely, the generic end state of the recently discovered monopole instability of Schwarzschild black holes in massive graviton theories.
Combining Conjugate Direction Methods with Stochastic Approximation of Gradients
Schraudolph, Nicol N.
Combining Conjugate Direction Methods with Stochastic Approximation of Gradients #3; Nicol N-8092 Zurich, Switzerland http://www.icos.ethz.ch/ Abstract The method of conjugate directions provides from conjugate gra- dient in the stochastic (online) setting, us- ing fast Hessian-gradient products
Combining Conjugate Direction Methods with Stochastic Approximation of Gradients
Schraudolph, Nicol N.
Combining Conjugate Direction Methods with Stochastic Approximation of Gradients Nicol N-8092 Z¨urich, Switzerland http://www.icos.ethz.ch/ Abstract The method of conjugate directions provides conjugate gra- dient in the stochastic (online) setting, us- ing fast Hessian-gradient products to set up
SampleRank: Training Factor Graphs with Atomic Gradients
McCallum, Andrew
a user-provided loss function to distribute stochastic gradients across an MCMC chain. As a result, parameter updates can be computed between arbitrary MCMC states. Sam- pleRank is not only faster than CD- expensive gradients between the ground-truth and samples along an MCMC chain yielding a stochastic
Destroying black holes with test bodies
Ted Jacobson; Thomas P. Sotiriou
2010-06-09T23:59:59.000Z
If a black hole can accrete a body whose spin or charge would send the black hole parameters over the extremal limit, then a naked singularity would presumably form, in violation of the cosmic censorship conjecture. We review some previous results on testing cosmic censorship in this way using the test body approximation, focusing mostly on the case of neutral black holes. Under certain conditions a black hole can indeed be over-spun or over-charged in this approximation, hence radiative and self-force effects must be taken into account to further test cosmic censorship.
Mineral Test Hole Regulatory Act (Tennessee)
Broader source: Energy.gov [DOE]
The Mineral Hole Regulatory Act is applicable to any person (individual, corporation, company, association, joint venture, partnership, receiver, trustee, guardian, executor, administrator,...
Lower Dimensional Black Holes: Inside and Out
R. B. Mann
1995-01-27T23:59:59.000Z
I survey the physics of black holes in two and three spacetime dimensions, with special attention given to an understanding of their exterior and interior properties.
Black Holes: from Speculations to Observations
Thomas W. Baumgarte
2006-04-13T23:59:59.000Z
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.
Herdeiro, Carlos A R
2014-01-01T23:59:59.000Z
We show that scalar hair can be added to rotating, vacuum black holes of general relativity. These hairy black holes (HBHs) clarify a lingering question concerning gravitational solitons: if a black hole can be added at the centre of a boson star, as it typically can for other solitons. We argue that it can, but only if it is spinning. The existence of such HBHs is related to the Kerr superradiant instability triggered by a massive scalar field. This connection leads to the following conjecture: a (hairless) black hole which is afflicted by the superradiant instability of a given field must allow hairy generalizations with that field.
A complete implementation of the conjugate gradient algorithm on a reconfigurable supercomputer
Dubois, David H [Los Alamos National Laboratory; Dubois, Andrew J [Los Alamos National Laboratory; Connor, Carolyn M [Los Alamos National Laboratory; Boorman, Thomas M [Los Alamos National Laboratory; Poole, Stephen W [ORNL
2008-01-01T23:59:59.000Z
The conjugate gradient is a prominent iterative method for solving systems of sparse linear equations. Large-scale scientific applications often utilize a conjugate gradient solver at their computational core. In this paper we present a field programmable gate array (FPGA) based implementation of a double precision, non-preconditioned, conjugate gradient solver for fmite-element or finite-difference methods. OUf work utilizes the SRC Computers, Inc. MAPStation hardware platform along with the 'Carte' software programming environment to ease the programming workload when working with the hybrid (CPUIFPGA) environment. The implementation is designed to handle large sparse matrices of up to order N x N where N <= 116,394, with up to 7 non-zero, 64-bit elements per sparse row. This implementation utilizes an optimized sparse matrix-vector multiply operation which is critical for obtaining high performance. Direct parallel implementations of loop unrolling and loop fusion are utilized to extract performance from the various vector/matrix operations. Rather than utilize the FPGA devices as function off-load accelerators, our implementation uses the FPGAs to implement the core conjugate gradient algorithm. Measured run-time performance data is presented comparing the FPGA implementation to a software-only version showing that the FPGA can outperform processors running up to 30x the clock rate. In conclusion we take a look at the new SRC-7 system and estimate the performance of this algorithm on that architecture.
Generalized Hooke's law for isotropic second gradient materials
F. dell'Isola; G. Sciarra; S. Vidoli
2010-08-17T23:59:59.000Z
In the spirit of Germain the most general objective stored elastic energy for a second gradient material is deduced using a literature result of Fortun\\'e & Vall\\'ee. Linear isotropic constitutive relations for stress and hyperstress in terms of strain and strain-gradient are then obtained proving that these materials are characterized by seven elastic moduli and generalizing previous studies by Toupin, Mindlin and Sokolowski. Using a suitable decomposition of the strain-gradient, it is found a necessary and sufficient condition, to be verified by the elastic moduli, assuring positive definiteness of the stored elastic energy. The problem of warping in linear torsion of a prismatic second gradient cylinder is formulated, thus obtaining a possible measurement procedure for one of the second gradient elastic moduli.
Tawfik, A., E-mail: a.tawfik@eng.mti.edu.eg [Egyptian Center for Theoretical Physics (ECTP), MTI University, 11571 Cairo (Egypt)
2013-07-01T23:59:59.000Z
We investigate the impacts of Generalized Uncertainty Principle (GUP) proposed by some approaches to quantum gravity such as String Theory and Doubly Special Relativity on black hole thermodynamics and Salecker-Wigner inequalities. Utilizing Heisenberg uncertainty principle, the Hawking temperature, Bekenstein entropy, specific heat, emission rate and decay time are calculated. As the evaporation entirely eats up the black hole mass, the specific heat vanishes and the temperature approaches infinity with an infinite radiation rate. It is found that the GUP approach prevents the black hole from the entire evaporation. It implies the existence of remnants at which the specific heat vanishes. The same role is played by the Heisenberg uncertainty principle in constructing the hydrogen atom. We discuss how the linear GUP approach solves the entire-evaporation-problem. Furthermore, the black hole lifetime can be estimated using another approach; the Salecker-Wigner inequalities. Assuming that the quantum position uncertainty is limited to the minimum wavelength of measuring signal, Wigner second inequality can be obtained. If the spread of quantum clock is limited to some minimum value, then the modified black hole lifetime can be deduced. Based on linear GUP approach, the resulting lifetime difference depends on black hole relative mass and the difference between black hole mass with and without GUP is not negligible.
Temperature, Energy, and Heat Capacity of Asymptotically Anti-De Sitter Black Holes
J. D. Brown; J. Creighton; R. B. Mann
1994-05-03T23:59:59.000Z
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.
Natural Conjugate Gradient on Complex Flag Manifolds for Complex Independent Subspace
Plumbley, Mark
conjugate gradient method yields better convergence compared to the natural gradient geodesic search method is the natural gradient geodesic search method (NGS), and the other is the natural conjugate gradient method (NCG the natural gradient or the Newton's method on complex manifolds, however, the behavior of the conjugate
Beltran-Royo, Cesar
A conjugate Rosen's gradient projection method with global line search for piecewise linear cutting plane method, simplex method, Rosen's gradient projection, conjugate gradient. 1 Introduction the zig-zagging of the gradient projection, we propose a conjugate gradient version of the face simplex
Efficient and robust gradient enhanced Kriging emulators.
Dalbey, Keith R.
2013-08-01T23:59:59.000Z
%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.
Construction and physical properties of Kerr black holes with scalar hair
Herdeiro, Carlos
2015-01-01T23:59:59.000Z
Kerr black holes with scalar hair are solutions of the Einstein-Klein-Gordon field equations describing regular (on and outside an event horizon), asymptotically flat black holes with scalar hair (arXiv:1403.2757). These black holes interpolate continuously between the Kerr solution and rotating boson stars in D=4 spacetime dimensions. Here we provide details on their construction, discussing properties of the ansatz, the field equations, the boundary conditions and the numerical strategy. Then, we present an overview of the parameter space of the solutions, and describe in detail the space-time structure of the black holes exterior geometry and of the scalar field for a sample of reference solutions. Phenomenological properties of potential astrophysical interest are also discussed, and the stability properties and possible generalizations are commented on. As supplementary material to this paper we make available numerical data files for the sample of reference solutions discussed, for public use.
The scattering matrix approach for the quantum black hole, an overview
G. 't Hooft
1996-07-09T23:59:59.000Z
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.
Quantum Entropy of Charged Rotating Black Holes
R. B. Mann
1996-07-10T23:59:59.000Z
I discuss a method for obtaining the one-loop quantum corrections to the tree-level entropy for a charged Kerr black hole. Divergences which appear can be removed by renormalization of couplings in the tree-level gravitational action in a manner similar to that for a static black hole.
Black holes cannot support conformal scalar hair
T. Zannias
1994-09-14T23:59:59.000Z
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.
Statistical constraints on binary black hole inspiral dynamics
Chad R. Galley; Frank Herrmann; John Silberholz; Manuel Tiglio; Gustavo Guerberoff
2010-05-30T23:59:59.000Z
We perform a statistical analysis of the binary black hole problem in the post-Newtonian approximation by systematically sampling and evolving the parameter space of initial configurations for quasi-circular inspirals. Through a principal component analysis of spin and orbital angular momentum variables we systematically look for uncorrelated quantities and find three of them which are highly conserved in a statistical sense, both as functions of time and with respect to variations in initial spin orientations. We also look for and find the variables that account for the largest variations in the problem. We present binary black hole simulations of the full Einstein equations analyzing to what extent these results might carry over to the full theory in the inspiral and merger regimes. Among other applications these results should be useful both in semi-analytical and numerical building of templates of gravitational waves for gravitational wave detectors.
Black Hole Fluctuations and Backreaction in Stochastic Gravity
Sukanya Sinha; Alpan Raval; B. L. Hu
2002-10-04T23:59:59.000Z
We present a framework for analyzing black hole backreaction from the point of view of quantum open systems using influence functional formalism. We focus on the model of a black hole described by a radially perturbed quasi-static metric and Hawking radiation by a conformally coupled massless quantum scalar field. It is shown that the closed-time-path (CTP) effective action yields a non-local dissipation term as well as a stochastic noise term in the equation of motion, the Einstein-Langevin equation. Once the thermal Green's function in a Schwarzschild background becomes available to the required accuracy the strategy described here can be applied to obtain concrete results on backreaction. We also present an alternative derivation of the CTP effective action in terms of the Bogolyubov coefficients, thus making a connection with the interpretation of the noise term as measuring the difference in particle production in alternative histories.
Phosphine Oxide Based Electron Transporting and Hole Blocking...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Oxide Based Electron Transporting and Hole Blocking Materials for Blue Electrophosphorescent Organic Light Emitting Phosphine Oxide Based Electron Transporting and Hole Blocking...
T-623: HP Business Availability Center Input Validation Hole...
Broader source: Energy.gov (indexed) [DOE]
3: HP Business Availability Center Input Validation Hole Permits Cross-Site Scripting Attacks T-623: HP Business Availability Center Input Validation Hole Permits Cross-Site...
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....
Black hole and holographic dark energy
Yun Soo Myung
2007-04-11T23:59:59.000Z
We discuss the connection between black hole and holographic dark energy. We examine the issue of the equation of state (EOS) for holographic energy density as a candidate for the dark energy carefully. This is closely related to the EOS for black hole, because the holographic dark energy comes from the black hole energy density. In order to derive the EOS of a black hole, we may use its dual (quantum) systems. Finally, a regular black hole without the singularity is introduced to describe an accelerating universe inside the cosmological horizon. Inspired by this, we show that the holographic energy density with the cosmological horizon as the IR cutoff leads to the dark energy-dominated universe with $\\omega_{\\rm \\Lambda}=-1$.
Black Hole Thermodynamics Based on Unitary Evolutions
Feng, Yu-Lei
2015-01-01T23:59:59.000Z
In this paper, we try to construct black hole thermodynamics based on the fact that, the formation and evaporation of a black hole can be described by quantum unitary evolutions. First, we show that the Bekenstein-Hawking entropy $S_{BH}$ cannot be a Boltzmann or thermal entropy. To confirm this statement, we show that the original black hole's "first law" cannot be treated as the first law of thermodynamics formally, due to some missing metric perturbations caused by matter. Then, by including those (quantum) metric perturbations, we show that the black hole formation and evaporation can be described in a unitary manner effectively, through a quantum channel between the exterior and interior of the event horizon. In this way, the paradoxes of information loss and firewall can be resolved effectively. Finally, we show that black hole thermodynamics can be constructed in an ordinary way, by constructing statistical mechanics.
An electromagnetic black hole made of metamaterials
Cheng, Qiang
2009-01-01T23:59:59.000Z
Traditionally, a black hole is a region of space with huge gravitational field in the means of general relativity, which absorbs everything hitting it including the light. In general relativity, the presence of matter-energy densities results in the motion of matter propagating in a curved spacetime1, which is similar to the electromagnetic-wave propagation in a curved space and in an inhomogeneous metamaterial2. Hence one can simulate the black hole using electromagnetic fields and metamaterials. In a recent theoretical work, an optical black hole has been proposed based on metamaterials, in which the numerical simulations showed a highly efficient light absorption3. Here we report the first experimental demonstration of electromagnetic black hole in the microwave frequencies. The proposed black hole is composed of non-resonant and resonant metamaterial structures, which can absorb electromagnetic waves efficiently coming from all directions due to the local control of electromagnetic fields. Hence the elect...
Black holes in Asymptotically Safe Gravity
Saueressig, Frank; D'Odorico, Giulio; Vidotto, Francesca
2015-01-01T23:59:59.000Z
Black holes are among the most fascinating objects populating our universe. Their characteristic features, encompassing spacetime singularities, event horizons, and black hole thermodynamics, provide a rich testing ground for quantum gravity ideas. In this note we observe that the renormalization group improved Schwarzschild black holes constructed by Bonanno and Reuter within Weinberg's asymptotic safety program constitute a prototypical example of a Hayward geometry used to model non-singular black holes within quantum gravity phenomenology. Moreover, they share many features of a Planck star: their effective geometry naturally incorporates the one-loop corrections found in the effective field theory framework, their Kretschmann scalar is bounded, and the black hole singularity is replaced by a regular de Sitter patch. The role of the cosmological constant in the renormalization group improvement process is briefly discussed.
Black Hole Superradiance in Dynamical Spacetime
William E. East; Fethi M. Ramazano?lu; Frans Pretorius
2014-03-14T23:59:59.000Z
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.
Finite difference schemes for second order systems describing black holes
Motamed, Mohammad; Kreiss, H-O. [NADA, Royal Institute of Technology, 10044 Stockholm (Sweden); Albert Einstein Institute, Max Planck Gesellschaft, Am Muehlenberg 1, D-14476 Golm (Germany); Babiuc, M.; Winicour, J. [Albert Einstein Institute, Max Planck Gesellschaft, Am Muehlenberg 1, D-14476 Golm (Germany); Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Szilagyi, B. [Albert Einstein Institute, Max Planck Gesellschaft, Am Muehlenberg 1, D-14476 Golm (Germany)
2006-06-15T23:59:59.000Z
In the harmonic description of general relativity, the principal part of Einstein's equations reduces to 10 curved space wave equations for the components of the space-time metric. We present theorems regarding the stability of several evolution-boundary algorithms for such equations when treated in second order differential form. The theorems apply to a model black hole space-time consisting of a spacelike inner boundary excising the singularity, a timelike outer boundary and a horizon in between. These algorithms are implemented as stable, convergent numerical codes and their performance is compared in a 2-dimensional excision problem.
Thermodynamics and Spectroscopy of Schwarzschild black hole surrounded by Quintessence
R Tharanath; V C Kuriakose
2013-01-11T23:59:59.000Z
The thermodynamic and spectroscopic behaviour of Schwarzschild black hole surrounded by quintessence are studied. We have derived the thermodynamic quantities and studied their behaviour for different values of quintessence parameter. We put the background space-time into the Kruskal-like coordinate to find the period with respect to Elucidean time. Also assuming that the adiabatic invariant obeys Bohr-Sommerfeld quantization rule, detailed study of area spectrum and entropy spectrum have been done for special cases of the quintessece state parameter. We find that the spectra are equally spaced.
Flow from a Tank Consider water flowing from a tank with water through a hole in its bottom. Denote
Feldman, Joel
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
Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method
Nocedal, Jorge
Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method Jos subroutines for automatically generating pre conditioners for the conjugate gradient method. It is designed. Additional Key Words and Phrases: Preconditioning, conjugate gradient method, quasi Newton method, Hessian
MacLachlan, Scott
COMPARISON OF THE DEFLATED PRECONDITIONED CONJUGATE GRADIENT METHOD AND ALGEBRAIC MULTIGRID algorithms such as the Preconditioned Conjugate Gradient (PCG) method. This paper considers the Deflated Preconditioned Conjugate Gradient (DPCG) method in which the rigid body modes of sets of elements
Optimization Online - A conjugate-gradient based approach for ...
Fredrik Carlsson
2008-02-29T23:59:59.000Z
Feb 29, 2008 ... In particular, it is noted that with a bound on the two-norm of the columns, the method is equivalent to the conjugate-gradient method. Further ...
on the connection between the conjugate gradient method and ...
2013-02-07T23:59:59.000Z
It is well known that the conjugate gradient method and a quasi-Newton method, using any well-defined update matrix from the one-parameter Broy- den family ...
Potential use of hollow spheres in dual gradient drilling
Vera Vera, Liliana
2002-01-01T23:59:59.000Z
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...
Function of the anterior gradient protein family in cancer
Fourtouna, Argyro
2009-01-01T23:59:59.000Z
Proteomic technologies verified Anterior Gradient 2, AGR-2, as a protein over-expressed in human cancers, including breast, prostate and oesophagus cancers, with the ability to inhibit the tumour suppressor protein p53. AGR-2 gene is a hormone...
Microsoft PowerPoint - High Gradient Inverse Free Electron Laser...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hi h G di t Hi h i High Gradient High energy gain Inverse Free Electron Laser at BNL P. Musumeci UCLA Department of Physics and Astronomy ATF user meeting April 2-3 2009 Outline...
CONSERVATION ECOLOGY -ORIGINAL RESEARCH Conservation through connectivity: can isotopic gradients
Richner, Heinz
CONSERVATION ECOLOGY - ORIGINAL RESEARCH Conservation through connectivity: can isotopic gradients Abstract Conservation of migratory wildlife requires knowledge of migratory connectivity between breeding conservation efforts for endangered migratory species (Webster et al. 2002; Rubenstein and Hobson 2004; Webster
A parametric study of thermomechanical behavior of functionally gradient materials
Chin, Che-Doong
1996-01-01T23:59:59.000Z
(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...
Computational Inversion of Electron Tomography Images -Gradient Flows
Texas at Austin, University of
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
Generation of Gradients Having Complex Shapes Using Microfluidic Networks
Prentiss, Mara
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
On the Time Times Temperature Bound
A. Lopez-Ortega
2010-06-28T23:59:59.000Z
Recently Hod proposes a lower bound on the relaxation time of a perturbed thermodynamic system. For gravitational systems this bound transforms into a condition on the fundamental quasinormal frequency. We test the bound in some spacetimes whose quasinormal frequencies are calculated exactly, as the three-dimensional BTZ black hole, the D-dimensional de Sitter spacetime, and the D-dimensional Nariai spacetime. We find that for some of these spacetimes their fundamental quasinormal frequencies do not satisfy the bound proposed by Hod.
A Spectral Conjugate Gradient Method for Unconstrained Optimization
Birgin, E. G. [Department of Computer Science, IME-USP, University of Sao Paulo, Rua do Matao, 1010 - Cidade Universitaria, 05508-900 Sao Paulo SP (Brazil)], E-mail: egbirgin@ime.usp.br; Martinez, J. M. [Department of Applied Mathematics, IMECC-UNICAMP, University of Campinas, CP 6065, 13081-970 Campinas SP (Brazil)], E-mail: martinez@ime.unicamp.br
2001-07-01T23:59:59.000Z
A family of scaled conjugate gradient algorithms for large-scale unconstrained minimization is defined. The Perry, the Polak-Ribiere and the Fletcher-Reeves formulae are compared using a spectral scaling derived from Raydan's spectral gradient optimization method. The best combination of formula, scaling and initial choice of step-length is compared against well known algorithms using a classical set of problems. An additional comparison involving an ill-conditioned estimation problem in Optics is presented.
Osteochondral Interface Tissue Engineering using Macroscopic Gradients of Physicochemical Signals
Dormer, Nathan Henry
2011-04-25T23:59:59.000Z
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...
Measurements of aerosol thermophoretic deposition: Transition with temperature gradient
Varma, A.; Tompson, R.V.; Loyalka, S.K. [Univ. of Missouri, Columbia, MO (United States)
1995-12-31T23:59:59.000Z
Thermophoresis is the motion of aerosol particles due to a temperature gradient in the suspending gas. The thermophoretic velocity V{sub T} is expressed as: where a {alpha} = thermal diffusivity v = kinematic viscosity H= Pr K Pr = Prandtl number K = dimensionless coefficient that is a function of several parameters (particle radius, thermal conductivity, gas properties, gas surface interactions). This report describes measurements of the effects of temperature gradients on the deposition of polystyrene latex particles.
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:...
E-Print Network 3.0 - advanced gradient based Sample Search Results
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Gradients of Poly(N-isopropylacrylamide) Polymer Brushes Prepared by Summary: , an electrochemical-potential-gradient- based method has been developed to generate chemical...
Mass Function Gradients and the Need for Dark Matter
Jason A. Taylor
1998-03-05T23:59:59.000Z
There is substantial evidence that the initial mass function (IMF) may be a function of the local star formation conditions. In particular, the IMF is predicted to flatten with increasing local luminosity density, with the formation of massive stars being preferentially enhanced in brighter regions. If IMF gradients are general features of galaxies, several previous astrophysical measurements, such as the surface mass densities of spirals (obtained assuming constant mass to light ratios), were plagued by substantial systematic errors. In this Letter, calculations which account for possible IMF gradients are presented of surface densities of spiral galaxies. Compared to previous estimates, the mass densities corrected for IMF gradients are higher in the outer regions of the disks. For a model based on the Milky Way but with an IMF scaled according to R136, the rotation curve without the traditional dark halo component falls with Galactocentric radius, though slower than it would without IMF gradients. For a second model of the Milky Way in which the IMF gradient is increased by 50%, the rotation curve is approximately flat in the outer disk, with a rotational velocity below ~220 km/s only before the traditional dark halo component is added. These results, if generalizable to other galaxies, not only call into question the assertion that dark matter halos are compatible with the flat rotation curves of spiral galaxies, but also may clarify our understanding of a wide variety of other astrophysical phenomena such as the G-dwarf problem, metallicity gradients, and the Tully-Fisher relation.
Blasthole timing control vibration, airblast and flyrock
Konya, C.J.; Walter, E.J.
1988-01-01T23:59:59.000Z
The authors say there is more to proper blasthole design than sequencing holes. Timing is one of the most important blast design variables. Timing controls the fragmentation size, piling of the broken material, maximum vibration level, airblast, flyrock, backbreak, endbreak and general overbreak. The authors explain how each of these items is controlled by timing.
Thermodynamics of Dyonic Lifshitz Black Holes
Tobias Zingg
2011-07-15T23:59:59.000Z
Black holes with asymptotic anisotropic scaling are conjectured to be gravity duals of condensed matter system close to quantum critical points with non-trivial dynamical exponent z at finite temperature. A holographic renormalization procedure is presented that allows thermodynamic potentials to be defined for objects with both electric and magnetic charge in such a way that standard thermodynamic relations hold. Black holes in asymptotic Lifshitz spacetimes can exhibit paramagnetic behavior at low temperature limit for certain values of the critical exponent z, whereas the behavior of AdS black holes is always diamagnetic.
Slim Holes for Small Power Plants
Finger, John T.
1999-08-06T23:59:59.000Z
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.
Black hole hair in higher dimensions
Chao Cao; Yi-Xin Chen; Jian-Long Li
2008-04-02T23:59:59.000Z
We study the property of matter in equilibrium with a static, spherically symmetric black hole in D-dimensional spacetime. It requires this kind of matter has an equation of state (\\omega\\equiv p_r/\\rho=-1/(1+2kn), k,n\\in \\mathbb{N}), which seems to be independent of D. However, when we associate this with specific models, some interesting limits on space could be found: (i)(D=2+2kn) while the black hole is surrounded by cosmic strings; (ii)the black hole can be surrounded by linear dilaton field only in 4-dimensional spacetime. In both cases, D=4 is special.
Dynamics of Scalar Fields in the Background of Rotating Black Holes
W. Krivan; P. Laguna; P. Papadopoulos
1996-06-04T23:59:59.000Z
A numerical study of the evolution of a massless scalar field in the background of rotating black holes is presented. First, solutions to the wave equation are obtained for slowly rotating black holes. In this approximation, the background geometry is treated as a perturbed Schwarzschild spacetime with the angular momentum per unit mass playing the role of a perturbative parameter. To first order in the angular momentum of the black hole, the scalar wave equation yields two coupled one-dimensional evolution equations for a function representing the scalar field in the Schwarzschild background and a second field that accounts for the rotation. Solutions to the wave equation are also obtained for rapidly rotating black holes. In this case, the wave equation does not admit complete separation of variables and yields a two-dimensional evolution equation. The study shows that, for rotating black holes, the late time dynamics of a massless scalar field exhibit the same power-law behavior as in the case of a Schwarzschild background independently of the angular momentum of the black hole.
Effects of black hole's gravitational field on the luminosity of a star during close encounter
Andreja Gomboc; Andrej Cadez
2005-02-24T23:59:59.000Z
To complement hydrodynamic studies of the tidal disruption of the star by a massive black hole, we present the study of stellar luminosity and its variations, produced by the strong gravitational field of the black hole during a close encounter. By simulating the relativistically moving star and its emitted light and taking into account general relativistic effects on particle and light trajectories, our results show that the black hole's gravity alone induces apparent stellar luminosity variations on typical timescales of a few r_g/c (=5 sec m_bh/10^6 M_\\odot) to a few 100 r_g/c (\\sim 10 min m_bh/10^6 M_\\odot), where r_g=Gm_bh/c^2. We discern different cases with respect to the strength of tidal interaction and focus on two: a) a star encountering a giant black hole traces space-time almost as a point particle, so that the apparent luminosity variations are dominated by clearly recognizable general relativistic effects and b) in a close encounter of a star with a black hole of similar size the stellar debris is spread about the black hole by processes where hydrodynamics plays an important role. We discuss limitations and results of our approach.
Falling through the black hole horizon
Brustein, Ram
2015-01-01T23:59:59.000Z
We consider the fate of a small classical object, a "stick", as it falls through the horizon of a large black hole (BH). Classically, the equivalence principle dictates that the stick is affected by small tidal forces, and Hawking's quantum-mechanical model of BH evaporation makes essentially the same prediction. If, on the other hand, the BH horizon is surrounded by a "firewall", the stick will be consumed as it falls through. We have recently extended Hawking's model by taking into account the quantum fluctuations of the geometry and the classical back-reaction of the emitted particles. Here, we calculate the strain exerted on the falling stick for our model. The strain depends on the near-horizon state of the Hawking pairs. We find that, after the Page time when the state of the pairs deviates significantly from maximal entanglement (as required by unitarity), the induced strain in our semiclassical model is still parametrically small. This is because the number of the disentangled pairs is parametrically ...
Black Hole Instabilities and Exponential Growth
Prabhu, Kartik
2015-01-01T23:59:59.000Z
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 $...
Thermodynamics of Schwarzschild-de Sitter black hole: thermal stability of Nariai black hole
Yun Soo Myung
2008-03-28T23:59:59.000Z
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.
Phase transitions and Geometrothermodynamics of Regular black holes
R. Tharanath; Jishnu Suresh; V. C. Kuriakose
2014-06-16T23:59:59.000Z
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.
I. Ya. Aref'eva; I. V. Volovich
2007-10-15T23:59:59.000Z
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.
Anosov maps with rectangular holes. Nonergodic cases.
Ingenier'ia. Universidad de la Rep'ublica C.C. 30, Montevideo, Uruguay EÂmail: roma@fing.edu.uy; Fax: (598 Partially supported by CONICYT (Uruguay). 1 #12; Running head: Anosov maps with rectangular holes Address
Radioactive hot cell access hole decontamination machine
Simpson, William E. (Richland, WA)
1982-01-01T23:59:59.000Z
Radioactive hot cell access hole decontamination machine. A mobile housing has an opening large enough to encircle the access hole and has a shielding door, with a door opening and closing mechanism, for uncovering and covering the opening. The housing contains a shaft which has an apparatus for rotating the shaft and a device for independently translating the shaft from the housing through the opening and access hole into the hot cell chamber. A properly sized cylindrical pig containing wire brushes and cloth or other disks, with an arrangement for releasably attaching it to the end of the shaft, circumferentially cleans the access hole wall of radioactive contamination and thereafter detaches from the shaft to fall into the hot cell chamber.
Hole Coupling Resonator for Free Electron Lasers
Xie, M.
2011-01-01T23:59:59.000Z
3. Total round-trip power loss, coupling efficiency and themicron. Total round-trip power loss and coupling efficiencythe total fractional power loss per round trip, the hole
Energy of 4-Dimensional Black Hole, etc
Dmitriy Palatnik
2011-07-18T23:59:59.000Z
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.
Tucker Wireline Open Hole Wireline Logging
Milliken, M.
2002-05-23T23:59:59.000Z
The Tucker Wireline unit ran a suite of open hole logs right behind the RMOTC logging contractor for comparison purposes. The tools included Dual Laterolog, Phased Induction, BHC Sonic, and Density-Porosity.
Horizon Operator Approach to Black Hole Quantization
G. 't Hooft
1994-02-21T23:59:59.000Z
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\
Towards Black Hole Entropy in Shape Dynamics
Gabriel Herczeg; Vasudev Shyam
2014-10-21T23:59:59.000Z
Shape dynamics is classical theory of gravity which agrees with general relativity in many important cases, but possesses different gauge symmetries and constraints. Rather than spacetime diffeomorphism invariance, shape dynamics takes spatial diffeomorphism invariance and spatial Weyl invariance as the fundamental gauge symmetries associated with the gravitational field. Since the area of the event horizon of a black hole transforms under a generic spatial Weyl transformation, there has been some doubt that one can speak sensibly about the thermodynamics of black holes in shape dynamics. The purpose of this paper is to show that by treating the event horizon of a black hole as an interior boundary, one can recover familiar notions of black hole thermodynamics in shape dynamics and define a gauge invariant entropy that agrees with general relativity.
Mutiny at the white-hole district
Carlos Barceló; Raúl Carballo-Rubio; Luis J. Garay
2014-07-05T23:59:59.000Z
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.
Notes on Black Hole Fluctuations and Backreaction
B. L. Hu; Alpan Raval; Sukanya Sinha
1999-01-05T23:59:59.000Z
In these notes we prepare the ground for a systematic investigation into the issues of black hole fluctuations and backreaction by discussing the formulation of the problem, commenting on possible advantages and shortcomings of existing works, and introducing our own approach via a stochastic semiclassical theory of gravity based on the Einstein-Langevin equation and the fluctuation-dissipation relation for a self-consistent description of metric fluctuations and dissipative dynamics of the black hole with backreaction of its Hawking radiance.
Gödel black hole, closed timelike horizon, and the study of particle emissions
Sourav Bhattacharya; Anirban Saha
2010-07-22T23:59:59.000Z
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.
Thermodynamics and evaporation of the noncommutative black hole
Yun Soo Myung; Yong-Wan Kim; Young-Jai Park
2007-01-21T23:59:59.000Z
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.
Solar Wind Forecasting with Coronal Holes
S. Robbins; C. J. Henney; J. W. Harvey
2007-01-09T23:59:59.000Z
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.
Non-axisymmetric wind-accretion simulations. II. Density gradients
M. Ruffert
1999-03-19T23:59:59.000Z
The hydrodynamics of a variant of classical Bondi-Hoyle-Lyttleton accretion is investigated: a totally absorbing sphere moves at various Mach numbers (3 and 10) relative to a medium, which is taken to be an ideal gas having a density gradient (of 3%, 20% or 100% over one accretion radius) perpendicular to the relative motion. Similarly to the 3D models published previously, both with velocity gradients and without, the models with a density gradient presented here exhibit non-stationary flow patterns, although the Mach cone remains fairly stable. The accretion rates of mass, linear and angular momenta do not fluctuate as strongly as published previously for 2D models. No obvious trend of the dependency of mass accretion rate fluctuations on the density gradient can be discerned. The average specific angular momentum accreted is roughly between zero and 70% of the total angular momentum available in the accretion cylinder in the cases where the average is prograde. Due to the large fluctuations during accretion, the average angular momentum of some models is retrograde by up to 25%. Small gradients hardly influence the average accretion rates as compared to accretion from a homogeneous medium, while very large ones succeed to dominate and form an accretion flow in which the sense of rotation is not inverted.
Geodesic Structure of the Schwarzschild Black Hole in Rainbow Gravity
Carlos Leiva; Joel Saavedra; Jose Villanueva
2008-12-09T23:59:59.000Z
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.
Fine-Scale Zonal Flow Suppression of Electron Temperature Gradient Turbulence
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
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.
Evolutionary and Gradient-Based Algorithms for Lennard-Jones Cluster Optimization
Schraudolph, Nicol N.
gradient method, while Section 3 shows how the asynchronous conjugate gradient method compares and randomized gradient methods with respect to their global search behavior. The randomized gradient method.g., conjugate gra- dient method) is started. With the local minima in- formation, the search is continued
The Solution of Systems of Linear Equations using the Conjugate Gradient Method
Schneider, Jean-Guy
The Solution of Systems of Linear Equations using the Conjugate Gradient Method on the Parallel gradient solver on the SPMDprogrammable MUSICsystem. We outline the conjugate gradient method, giveassociativity of the floating point addition. We investi gate the speed of convergence of the conjugate gradient method
Newton-conjugate-gradient methods for solitary wave computations Jianke Yang
Yang, Jianke
Newton-conjugate-gradient methods for solitary wave computations Jianke Yang Department's method Conjugate-gradient methods a b s t r a c t In this paper, the Newton-conjugate-gradient methods the linearization operator is self-adjoint, the preconditioned conjugate-gradient method is pro- posed to solve
A NONLINEAR CONJUGATE GRADIENT METHOD WITH A STRONG GLOBAL CONVERGENCE PROPERTY
Yuan, Ya-xiang
A NONLINEAR CONJUGATE GRADIENT METHOD WITH A STRONG GLOBAL CONVERGENCE PROPERTY Y. H. DAI AND Y182 Abstract. Conjugate gradient methods are widely used for unconstrained optimization, especially large scale gradient methods. This paper presents a new version of the conjugate gradient method, which converges
Algorithm 851: CG DESCENT, a Conjugate Gradient Method with Guaranteed Descent
Zhang, Hongchao
Algorithm 851: CG DESCENT, a Conjugate Gradient Method with Guaranteed Descent WILLIAM W. HAGER In Hager and Zhang [2005] we introduce a new nonlinear conjugate gradient method for solving con- jugate gradient research. The iterates xk, k 0, in conjugate gradient methods satisfy
A planar ion trap chip with integrated structures for an adjustable magnetic field gradient
Wunderlich, Christof
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
C. Tadhunter; A. Marconi; D. Axon; K. Wills; T. G. Robinson; N. Jackson
2003-02-25T23:59:59.000Z
We use a combination of high spatial resolution optical and near-IR spectroscopic data to make a detailed study of the kinematics of the NLR gas in the near-nuclear regions of the powerful, FRII radio galaxy Cygnus A (z=0.0560), with the overall goal of placing limits on the mass of any supermassive black hole in the core. Our K-band infrared observations (0.75 arcsec seeing) -- taken with NIRSPEC on the Keck II telescope -- show a smooth rotation pattern across the nucleus in the Paschen alpha and H_2 emission lines along a slit position (PA180) close to perpendicular to the radio axis, however, there is no evidence for such rotation along the radio axis (PA105). Higher spatial resolution observations of the [OIII]5007 emission line -- taken with STIS on the Hubble Space Telescope (HST) -- confirm the general rotation pattern of the gas in the direction perpendicular to the radio axis, and provide evidence for steep velocity gradients within a radius of 0.1 arcsec of the core. The circular velocities measured from both the Keck and HST data lead to an estimate of the mass of the supermassive black hole of 2.5+/-0.7x10^9 solar masses. For the host galaxy properties of Cygnus A, this mass is consistent with the global correlations between black hole mass and host galaxy properties deduced for non-active galaxies. Therefore, despite the extreme power of its radio source and the quasar-like luminosity of its AGN, the black hole in Cygnus A is not unusually massive considering theluminosity of its host galaxy. Indeed, the estimated mass of the black hole in Cygnus A is similar to that inferred for the supermassive black hole in the FRI radio galaxy M87, despite the fact that the AGN and radio jets of Cygnus A are 2 -- 3 orders of magnitude more powerful.
Geosynthetics in a salinity-gradient solar pond environment
Lichwardt, M.A.; Comer, A.I.
1997-11-01T23:59:59.000Z
This paper describes the latest in salinity-gradient solar pond lining systems. The high-temperature, high-salinity environment unique to a salinity-gradient solar pond resulted in failure of the geomembrane liner at the El Paso Solar Pond Test Facility after only eight years of operation. Research involved in pond reconstruction led to the selection of a lining system consisting of a flexible polypropylene (PP) geomembrane for the sidewalls and a specially formulated geosynthetic clay liner (GCL) on the bottom of the pond. The two liners have been installed and a comprehensive test program is being conducted to measure their performance. The environment encountered in a salinity-gradient solar pond will be discussed as well as material selection criteria and the design of the two liners. Preliminary results of the GCL performance monitoring will also be presented.
Gradient isolator for flow field of fuel cell assembly
Ernst, William D. (Troy, NY)
1999-01-01T23:59:59.000Z
Isolator(s) include isolating material and optionally gasketing material strategically positioned within a fuel cell assembly. The isolating material is disposed between a solid electrolyte and a metal flow field plate. Reactant fluid carried by flow field plate channel(s) forms a generally transverse electrochemical gradient. The isolator(s) serve to isolate electrochemically a portion of the flow field plate, for example, transversely outward from the channel(s), from the electrochemical gradient. Further, the isolator(s) serve to protect a portion of the solid electrolyte from metallic ions.
Velocity bunching in travelling wave accelerator with low acceleration gradient
Huang, Rui-Xuan; Li, Wei-Wei; Jia, Qi-Ka
2013-01-01T23:59:59.000Z
We present the analytical and simulated results concerning the influences of the acceleration gradient in the velocity bunching process, which is a bunch compression scheme that uses a traveling wave accelerating structure as a compressor. Our study shows that the bunch compression application with low acceleration gradient is more tolerant to phase jitter and more successful to obtain compressed electron beam with symmetrical longitudinal distribution and low energy spread. We also present a transverse emittance compensation scheme to compensate the emittance growth caused by the increasing of the space charge force in the compressing process that is easy to be adjusted for different compressing factors.
Discontinuous Galerkin finite element methods for gradient plasticity.
Garikipati, Krishna. (University of Michigan, Ann Arbor, MI); Ostien, Jakob T.
2010-10-01T23:59:59.000Z
In this report we apply discontinuous Galerkin finite element methods to the equations of an incompatibility based formulation of gradient plasticity. The presentation is motivated with a brief overview of the description of dislocations within a crystal lattice. A tensor representing a measure of the incompatibility with the lattice is used in the formulation of a gradient plasticity model. This model is cast in a variational formulation, and discontinuous Galerkin machinery is employed to implement the formulation into a finite element code. Finally numerical examples of the model are shown.
Gradient isolator for flow field of fuel cell assembly
Ernst, W.D.
1999-06-15T23:59:59.000Z
Isolator(s) include isolating material and optionally gasketing material strategically positioned within a fuel cell assembly. The isolating material is disposed between a solid electrolyte and a metal flow field plate. Reactant fluid carried by flow field plate channel(s) forms a generally transverse electrochemical gradient. The isolator(s) serve to isolate electrochemically a portion of the flow field plate, for example, transversely outward from the channel(s), from the electrochemical gradient. Further, the isolator(s) serve to protect a portion of the solid electrolyte from metallic ions. 4 figs.
Maximilian Ruffert
1996-05-14T23:59:59.000Z
We investigate the hydrodynamics of a variant of classical Bondi-Hoyle-Lyttleton accretion: a totally absorbing sphere moves at various Mach numbers (3 and 10) relative to a medium, which is taken to be an ideal gas having a velocity gradient (of 3% or 20% over one accretion radius) perpendicular to the relative motion. We examine the influence of the Mach number of the flow and the strength of the gradient upon the physical behaviour of the flow and the accretion rates of the angular momentum in particular. The hydrodynamics is modeled by the ``Piecewise Parabolic Method'' (PPM). The resolution in the vicinity of the accretor is increased by multiply nesting several grids around the sphere. Similarly to the 3D models without gradients published previously, models exhibit non-stationary flow patterns, although the Mach cone remains fairly stable. The accretion rates of mass, linear and angular momenta do not fluctuate as strongly as published previously for 2D models, but similarly to the 2D models, transient disks form around the accretor that alternate their direction of rotation with time. The average specific angular momentum accreted is roughly between 7% and 70% of the total angular momentum available in the accretion cylinder and is always smaller than the value of a vortex with Kepler velocity around the surface of the accretor. The fluctuations of the mass accretion rate in the models with small gradients (2%) are similar to the values of the models without gradients, while the models with large gradients (20%) exhibit larger fluctuations. The mass accretion rate is maximal when the specific angular momentum is zero, while the specific entropy tends to be smaller when the disks are prograde.
Larmor radius size density holes discovered in the solar wind upstream of Earth's bow shock
California at Berkeley, University of
Larmor radius size density holes discovered in the solar wind upstream of Earth's bow shock G. K. Cao Key Laboratory for Space Weather, CSSAR, CAS, Beijing, China K. Meziane Physics Department that are five or more times the solar wind density. Particle distributions show the steepened edge can behave
Perturbative String Thermodynamics near Black Hole Horizons
Thomas G. Mertens; Henri Verschelde; Valentin I. Zakharov
2014-10-29T23:59:59.000Z
We provide further computations and ideas to the problem of near-Hagedorn string thermodynamics near (uncharged) black hole horizons, building upon our earlier work JHEP 1403 (2014) 086. The relevance of long strings to one-loop black hole thermodynamics is emphasized. We then provide an argument in favor of the absence of $\\alpha'$-corrections for the (quadratic) heterotic thermal scalar action in Rindler space. We also compute the large $k$ limit of the cigar orbifold partition functions (for both bosonic and type II superstrings) which allows a better comparison between the flat cones and the cigar cones. A discussion is made on the general McClain-Roth-O'Brien-Tan theorem and on the fact that different torus embeddings lead to different aspects of string thermodynamics. The black hole/string correspondence principle for the 2d black hole is discussed in terms of the thermal scalar. Finally, we present an argument to deal with arbitrary higher genus partition functions, suggesting the breakdown of string perturbation theory (in $g_s$) to compute thermodynamical quantities in black hole spacetimes.
The Environmental Impact of Supermassive Black Holes
Abraham Loeb
2004-08-10T23:59:59.000Z
The supermassive black holes observed at the centers of almost all present-day galaxies, had a profound impact on their environment. I highlight the principle of self-regulation, by which supermassive black holes grow until they release sufficient energy to unbind the gas that feeds them from their host galaxy. This principle explains several observed facts, including the correlation between the mass of a central black hole and the depth of the gravitational potential well of its host galaxy, and the abundance and clustering properties of bright quasars in the redshift interval of z~2-6. At lower redshifts, quasars might have limited the maximum mass of galaxies through the suppression of cooling flows in X-ray clusters. The seeds of supermassive black holes were likely planted in dwarf galaxies at redshifts z>10, through the collapse of massive or supermassive stars. The minimum seed mass can be identified observationally through the detection of gravitational waves from black hole binaries by Advanced LIGO or LISA. Aside from shaping their host galaxies, quasar outflows filled the intergalactic medium with magnetic fields and heavy elements. Beyond the reach of these outflows, the brightest quasars at z>6 have ionized exceedingly large volumes of gas (tens of comoving Mpc) prior to global reionization, and must have suppressed the faint end of the galaxy luminosity function in these volumes before the same occurred through the rest of the universe.
Black Holes with Flavors of Quantum Hair?
Gia Dvali
2006-07-20T23:59:59.000Z
We show that black holes can posses a long-range quantum hair of super-massive tensor fields, which can be detected by Aharonov-Bohm tabletop interference experiments, in which a quantum-hairy black hole, or a remnant particle, passes through the loop of a magnetic solenoid. The long distance effect does not decouple for an arbitrarily high mass of the hair-providing field. Because Kaluza-Klein and String theories contain infinite number of massive tensor fields, we study black holes with quantum Kaluza-Klein hair. We show that in five dimensions such a black hole can be interpreted as a string of `combed' generalized magnetic monopoles, with their fluxes confined along it. For the compactification on a translation-invariant circle, this substructure uncovers hidden flux conservation and quantization of the monopole charges, which constrain the quantum hair of the resulting four-dimensional black hole. For the spin-2 quantum hair this result is somewhat unexpected, since the constituent `magnetic' charges have no `electric' counterparts. Nevertheless, the information about their quantization is encoded in singularity.
Holographic superconductor in the exact hairy black hole
Yun Soo Myung; Chanyong Park
2011-09-13T23:59:59.000Z
We study the charged black hole of hyperbolic horizon with scalar hair (charged Martinez-Troncoso-Zanelli: CMTZ black hole) as a model of analytic hairy black hole for holographic superconductor. For this purpose, we investigate the second order phase transition between CMTZ and hyperbolic Reissner-Nordstr\\"om-AdS (HRNAdS) black holes. However, this transition unlikely occur. As an analytic treatment for holographic superconductor, we develop superconductor in the bulk and superfluidity on the boundary using the CMTZ black hole below the critical temperature. The presence of charge destroys the condensates around the zero temperature, which is in accord with the thermodynamic analysis of the CMTZ black hole.
Measuring Hawking Radiation of a Kerr-Newman Black Hole in a Superconducting Transmission Line
X. G. Lan; D. Y. Chen; L. F. Wei
2014-03-21T23:59:59.000Z
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.
Thermalization with chemical potentials, and higher spin black holes
Gautam Mandal; Ritam Sinha; Nilakash Sorokhaibam
2015-03-06T23:59:59.000Z
We study the long time behaviour of local observables following a quantum quench in 1+1 dimensional conformal field theories possessing additional conserved charges besides the energy. We show that the expectation value of an arbitrary string of {\\it local} observables supported on a finite interval exponentially approaches an equilibrium value. The equilibrium is characterized by a temperature and chemical potentials defined in terms of the quenched state. For an infinite number of commuting conserved charges, the equilibrium ensemble is a generalized Gibbs ensemble (GGE). We compute the thermalization rate in a systematic perturbation in the chemical potentials, using a new technique to sum over an infinite number of Feynman diagrams. The above technique also allows us to compute relaxation times for thermal Green's functions in the presence of an arbitrary number of chemical potentials. In the context of a higher spin (hs[\\lambda]) holography, the partition function of the final equilibrium GGE is known to agree with that of a higher spin black hole. The thermalization rate from the CFT computed in our paper agrees with the quasinormal frequency of a scalar field in this black hole.
Thermalization with chemical potentials, and higher spin black holes
Gautam Mandal; Ritam Sinha; Nilakash Sorokhaibam
2015-01-19T23:59:59.000Z
We study the long time behaviour of local observables following a quantum quench in 1+1 dimensional conformal field theories possessing additional conserved charges besides the energy. We show that the expectation value of an arbitrary string of {\\it local} observables supported on a finite interval exponentially approaches an equilibrium value. The equilibrium is characterized by a temperature and chemical potentials defined in terms of the quenched state. For an infinite number of commuting conserved charges, the equilibrium ensemble is a generalized Gibbs ensemble (GGE). We compute the thermalization rate in a systematic perturbation in the chemical potentials, using a new technique to sum over an infinite number of Feynman diagrams. The above technique also allows us to compute relaxation times for thermal Green's functions in the presence of an arbitrary number of chemical potentials. In the context of a higher spin (hs[\\lambda]) holography, the partition function of the final equilibrium GGE is known to agree with that of a higher spin black hole. The thermalization rate from the CFT computed in our paper agrees with the quasinormal frequency of a scalar field in this black hole.
Computing several eigenpairs of Hermitian problems by conjugate gradient iterations
Ovtchinnikov, E.E. [Harrow School of Computer Science, University of Westminster, Watford Road, Northwick Park, London HA1 3TP (United Kingdom)], E-mail: e_ovtchinnikov@hotmail.com
2008-11-20T23:59:59.000Z
The paper is concerned with algorithms for computing several extreme eigenpairs of Hermitian problems based on the conjugate gradient method. We analyse computational strategies employed by various algorithms of this kind reported in the literature and identify their limitations. Our criticism is illustrated by numerical tests on a set of problems from electronic structure calculations and acoustics.
Soil macroaggregate dynamics in a mountain spatial climate gradient
Paris-Sud XI, Université de
Soil macroaggregate dynamics in a mountain spatial climate gradient Lauric Cécillon1,2,* , Nilvania://lauric.cecillon.free.fr/ Key words: Mountain soils; Climate change; Soil aggregation; Soil organic matter; Near infrared reflectance spectroscopy; Soil threats Biogeochemistry 97: 31-43 (2010) http://dx.doi.org/10.1007/s10533
Gradient Improvement by Removal of Identified Local Defects
R.L. Geng, W.A. Clemens, C.A. Cooper, H. Hayano, K. Watanabe
2011-07-01T23:59:59.000Z
Recent experience of ILC cavity processing and testing at Jefferson Lab has shown that some 9-cell cavities are quench limited at a gradient in the range of 15-25 MV/m. Further studies reveal that these quench limits are often correlated with sub-mm sized and highly localized geometrical defects at or near the equator weld. There are increasing evidence to show that these genetic defects have their origin in the material or in the electron beam welding process (for example due to weld irregularities or splatters on the RF surface and welding porosity underneath the surface). A local defect removal method has been proposed at Jefferson Lab by locally re-melting the niobium material. Several 1-cell cavities with known local defects have been treated by using the JLab local e-beam re-melting method, resulting in gradient and Q0 improvement. We also sent 9-cell cavities with known gradient limiting local defects to KEK for local grinding and to FNAL for global mechanical polishing. We report on the results of gradient improvements by removal of local defects in these cavities.
Online gradient descent learning algorithms Yiming Ying and Massimiliano Pontil
Pontil, Massimiliano
Online gradient descent learning algorithms Yiming Ying and Massimiliano Pontil Department of Computer Science, University College London Gower Street, London, WC1E 6BT, England, UK {y.ying, m, 62L20. Contact author: Yiming Ying, Telephone: +44 (0)20 7387 0374, Fax: +44 (0)20 7387 1397 1 #12
Online gradient descent learning algorithm Yiming Ying and Massimiliano Pontil
Ying, Yiming
Online gradient descent learning algorithm Yiming Ying and Massimiliano Pontil Department of Computer Science, University College London Gower Street, London, WC1E 6BT, England, UK {y.ying, m Numbers: 68Q32, 68T05, 62J02, 62L20. Contact author: Yiming Ying, Telephone: +44 (0)20 7679 0374, Fax
Simulation of IPA Gradients in Hybrid Network Systems Benjamin Melamed
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
Scaling limits for gradient systems in random environment
P. Goncalves; M. D. Jara
2007-02-17T23:59:59.000Z
For interacting particle systems that satisfies the gradient condition, the hydrodynamic limit and the equilibrium fluctuations are well known. We prove that under the presence of a symmetric random environment, these scaling limits also hold for almost every choice of the environment, with homogenized coefficients that does not depend on the particular realization of the random environment.
Seasonal mass balance gradients in Norway L. A. Rasmussen1
Rasmussen, L.A.
16 Aug 05 Seasonal mass balance gradients in Norway L. A. Rasmussen1 and L. M. Andreassen2 1 Norwegian Water Resources and Energy Directorate (NVE) P. O. Box 5091 Majorstua, N-0301 Oslo, Norway in Norway exists in their profiles of both seasonal balances, winter bw(z) and summer bs(z). Unlike many
The Urban Environmental Gradient: Anthropogenic Influences on the
Georgia, through Atlanta, to the Gulf of Mexico and reflects a steep gradient in population density from as vehicular traffic. Introduction Many of the common anthropogenic pollution problems are focused in urban geographic areas. Suburbia does not contribute much by way of industrial pollution, but it does serve
Continuous Edge Gradient-Based Template Matching for Articulated
Zachmann, Gabriel
Zachmann IfI Technical Report Series IfI-09-01 #12;Impressum Publisher: Institut fÃ¼r Informatik, Technische (Technical Computer Science) Prof. Dr. Gabriel Zachmann (Computer Graphics) #12;Continuous Edge Gradient-Based Template Matching for Articulated Objects Daniel Mohr and Gabriel Zachmann Abstract Detection
Non-axisymmetric wind-accretion simulations; 2, Density gradients
Ruffert, M
1999-01-01T23:59:59.000Z
The hydrodynamics of a variant of classical Bondi-Hoyle-Lyttleton accretion is investigated: a totally absorbing sphere moves at various Mach numbers (3 and 10) relative to a medium, which is taken to be an ideal gas having a density gradient (of 3%, 20% or 100% over one accretion radius) perpendicular to the relative motion. Similarly to the 3D models published previously, both with velocity gradients and without, the models with a density gradient presented here exhibit non-stationary flow patterns, although the Mach cone remains fairly stable. The accretion rates of mass, linear and angular momenta do not fluctuate as strongly as published previously for 2D models. No obvious trend of the dependency of mass accretion rate fluctuations on the density gradient can be discerned. The average specific angular momentum accreted is roughly between zero and 70% of the total angular momentum available in the accretion cylinder in the cases where the average is prograde. Due to the large fluctuations during accretio...
A distributed accelerated gradient algorithm for distributed model predictive
Como, Giacomo
of hydro power plants is to manage the available water resources efficiently, while following an optimal is applied to the power reference tracking problem of a hydro power valley (HPV) system. The applied power control, Distributed optimization, Accelerated gradient algorithm, Model predictive control
A study of microbend test by strain gradient plasticity
Hsia, K Jimmy
A study of microbend test by strain gradient plasticity W. Wanga , Y. Huangb, *, K.J. Hsiac , K with plastic deformation is on the order of microns. This size effect cannot be explained by classical plasticity theories since their constitutive relations do not have an intrinsic material length. Strain
Treated Wastewater Effluent Reduces Sperm Motility Along an Osmolality Gradient
Julius, Matthew L.
Treated Wastewater Effluent Reduces Sperm Motility Along an Osmolality Gradient H. L. Schoenfuss Ã? 2008 Ã? 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
GEOTHERMAL GRADIENT DATA FOR UTAH Robert E. Blackett
Laughlin, Robert B.
GEOTHERMAL GRADIENT DATA FOR UTAH by Robert E. Blackett February 2004 UTAH GEOLOGICAL SURVEY Â 1:750,000 scale map, showing geology; thermal wells, springs, and geothermal areas; and locations available sources including the Southern Methodist University Geothermal Laboratory, U.S. Geological Survey
Overview of high gradient SRF R&D for ILC cavities at Jefferson Lab
Geng, Rongli [JLAB
2009-11-01T23:59:59.000Z
We report the progress on high gradient R&D of ILC cavities at Jefferson Lab (JLab) since the Beijing workshop. Routine 9-cell cavity electropolishing (EP) processing and RF testing has been enhanced with added surface mapping and T-mapping instrumentations. 12 new 9-cell cavities (10 of them are baseline fine-grain TESLA-shape cavities: 5 built by ACCEL/Research Instruments, 4 by AES and 1 by JLab; 2 of them are alternative cavities: 1 fine-grain ICHIRO-shape cavity built by KEK/Japan industry and 1 large-grain TESLA-shape cavity built by JLab) are EP processed and tested. 76 EP cycles are accumulated, corresponding to more than 200 hours of active EP time. Field emission (FE) and quench behaviors of electropolished 9-cell cavities are studied. EP process continues to be optimized, resulting in advanced procedures and hence improved cavity performance. Several 9-cell cavities reached 35 MV/m after the first light EP processing. FE-free performance has been demonstrated in 9-cell cavities in 35-40 MV/m range. 1-cell cavity studies explore new techniques for defect removal as well as advanced integrated cavity processing. Surface studies of niobium samples electropolished together with real cavities provide new insight into the nature of field emitters. Close cooperation with the US cavity fabrication industry has been undertaking with the successful achievement of 41 MV/m for the first time in a 9-cell ILC cavity built by AES. As the size of the data set grows, it is now possible to construct gradient yield curves, from which one can see that significant progress has been made in raising the high gradient yield.
Geoffrey Lovelace
2008-12-16T23:59:59.000Z
At early times in numerical evolutions of binary black holes, current simulations contain an initial burst of spurious gravitational radiation (also called "junk radiation") which is not astrophysically realistic. The spurious radiation is a consequence of how the binary-black-hole initial data are constructed: the initial data are typically assumed to be conformally flat. In this paper, I adopt a curved conformal metric that is a superposition of two boosted, non-spinning black holes that are approximately 15 orbits from merger. I compare junk radiation of the superposed-boosted-Schwarzschild (SBS) initial data with the junk of corresponding conformally flat, maximally sliced (CFMS) initial data. The SBS junk is smaller in amplitude than the CFMS junk, with the junk's leading-order spectral modes typically being reduced by a factor of order two or more.
Gravitational Lensing by Self-Dual Black Holes in Loop Quantum Gravity
Sahu, Satyabrata; Narasimha, D
2015-01-01T23:59:59.000Z
We study gravitational lensing by a recently proposed black hole solution in Loop Quantum Gravity. We highlight the fact that the quantum gravity corrections to the Schwarzschild metric in this model evade the `mass suppression' effects (that the usual quantum gravity corrections are susceptible to) by virtue of one of the parameters in the model being dimensionless, which is unlike any other quantum gravity motivated parameter. Gravitational lensing in the strong and weak deflection regimes is studied and a sample consistency relation is presented which could serve as a test of this model. We discuss that though the consistency relation for this model is qualitatively similar to what would have been in Brans-Dicke, in general it can be a good discriminator between many alternative theories. Although the observational prospects do not seem to be very optimistic even for a galactic supermassive black hole case, time delay between relativistic images for billion solar mass black holes in other galaxies might be...
Wang, Yunliang, E-mail: ylwang@ustb.edu.cn; Lü, Xiaoxia [Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)] [Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)
2014-02-15T23:59:59.000Z
The modulational instability of quantum electrostatic acoustic waves in electron-hole quantum semiconductor plasmas is investigated using the quantum hydrodynamic model, from which a modified nonlinear Schrödinger equation with damping effects is derived using the reductive perturbation method. Here, we consider the combined effects of quantum recoil, quantum degenerate pressures, as well as the exchange-correlation effect standing for the electrons (holes) spin. The modulational instability for different semiconductors (GaAs, GaSb, and InP) is discussed. The collision between electron (hole) and phonon is also investigated. The permitted maximum time for modulational instability and the damping features of quantum envelope solitary wave are all determined by the collision. The approximate solitary solution with damping effects is presented in weak collision limit. The damping properties were discussed by numerical method.
Horndeski meets McVittie: A scalar field theory for accretion onto cosmological black holes
Niayesh Afshordi; Michele Fontanini; Daniel C. Guariento
2014-08-24T23:59:59.000Z
We show that the generalized McVittie spacetime, which represents a black hole with time-dependent mass in an expanding universe, is an exact solution of a subclass of the Horndeski family of actions. The heat-flow term responsible for the energy transfer between the black hole and the cosmological background is generated by the higher-order kinetic gravity braiding term, which generalizes the cuscuton action that yields McVittie with constant mass as a solution. Finally, we show that this generalization can be understood in terms of a duality realized by a disformal transformation, connecting the cuscuton field theory to an extension of the Horndeski action which does not propagate any scalar degrees of freedom. Our finding opens a novel window into studies of non-trivial interactions between dark energy/modified gravity theories and astrophysical black holes.
3D SPH Simulations of Shocks in Accretion Flows around black holes
G. Gerardi; D. Molteni; V. Teresi
2005-01-25T23:59:59.000Z
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.
Transient evolution of solitary electron holes in low pressure laboratory plasma
Choudhary, Mangilal; Mukherjee, Subroto
2015-01-01T23:59:59.000Z
Solitary electrons holes (SEHs) are localized electrostatic positive potential structures in collisionless plasmas. These are vortex-like structures in the electron phase space. Its existence is cause of distortion of the electron distribution in the resonant region. These are explained theoretically first time by Schamel et.al [Phys. Scr. 20, 336 (1979) and Phys. Plasmas 19, 020501 (2012)]. Propagating solitary electron holes can also be formed in a laboratory plasma when a fast rising high positive voltage pulse is applied to a metallic electrode [Kar et. al., Phys. Plasmas 17, 102113 (2010)] immersed in a low pressure plasma. The temporal evolution of these structures can be studied by measuring the transient electron distribution function (EDF). In the present work, transient EDF is measured after formation of a solitary electron hole in nearly uniform, unmagnetized, and collisionless plasma for applied pulse width and, where and are applied pulse width and inverse of ion plasma frequency respectively. Fo...
Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre
Sheperd Doeleman; Jonathan Weintroub; Alan E. E. Rogers; Richard Plambeck; Robert Freund; Remo P. J. Tilanus; Per Friberg; Lucy M. Ziurys; James M. Moran; Brian Corey; Ken H. Young; Daniel L. Smythe; Michael Titus; Daniel P. Marrone; Roger J. Cappallo; Douglas C. J. Bock; Geoffrey C. Bower; Richard Chamberlin; Gary R. Davis; Thomas P. Krichbaum; James Lamb; Holly Maness; Arthur E. Niell; Alan Roy; Peter Strittmatter; Daniel Werthimer; Alan R. Whitney; David Woody
2008-09-15T23:59:59.000Z
The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation (ref 1). Sagittarius A*, the compact source of radio, infrared and X-ray emission at the centre of the Milky Way, is the closest example of this phenomenon, with an estimated black hole mass that is 4 million times that of the Sun (refs. 2,3). A long-standing astronomical goal is to resolve structures in the innermost accretion flow surrounding Sgr A* where strong gravitational fields will distort the appearance of radiation emitted near the black hole. Radio observations at wavelengths of 3.5 mm and 7 mm have detected intrinsic structure in Sgr A*, but the spatial resolution of observations at these wavelengths is limited by interstellar scattering (refs. 4-7). Here we report observations at a wavelength of 1.3 mm that set a size of 37 (+16, -10; 3-sigma) microarcseconds on the intrinsic diameter of Sgr A*. This is less than the expected apparent size of the event horizon of the presumed black hole, suggesting that the bulk of SgrA* emission may not be not centred on the black hole, but arises in the surrounding accretion flow.
Particle-hole symmetry parameters for nuclei
Ian Bentley
2015-03-10T23:59:59.000Z
Two parameters, nu and zeta, motivated by particle-hole symmetry are introduced. These parameters are determined using the number of proton (or neutron) particles and holes counted from neighboring shell closures. The new parameters can be used to evaluate particle-hole and proton-neutron symmetries of adopted B(E2) values, which indicate that both symmetries are approximate for A>100. The combined symmetries motivate empirical fits of binding energies and the energy ratio E(4_1^+)/E(2_1^+). A global binding energy fit consisting of a traditional liquid droplet and one new shell term, comprised of a function of nu and zeta, reproduces the experimental binding energies of 2353 nuclei with an r.m.s. standard deviation of 1.55 MeV.
Neutrino Majorana Mass from Black Hole
Yosuke Uehara
2002-05-25T23:59:59.000Z
We propose a new mechanism to generate the neutrino Majorana mass in TeV-scale gravity models. The black hole violates all non-gauged symmetries and can become the origin of lepton number violating processes. The fluctuation of higher-dimensional spacetime can result in the production of a black hole, which emits 2 neutrinos. If neutrinos are Majorana particles, this process is equivalent to the free propagation of a neutrino with the insertion of the black hole. From this fact, we derive the neutrino Majorana mass. The result is completely consistent with the recently observed evidence of neutrinoless double beta decay. And the obtained neutrino Majorana mass satisfies the constraint from the density of the neutrino dark matter, which affects the cosmic structure formation. Furthermore, we can explain the ultrahigh energy cosmic rays by the Z-burst scenario with it.
Black Hole Chromosphere at the LHC
Luis Anchordoqui; Haim Goldberg
2003-02-26T23:59:59.000Z
If the scale of quantum gravity is near a TeV, black holes will be copiously produced at the 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.
Black Hole Complementarity in Gravity's Rainbow
Gim, Yongwan
2015-01-01T23:59:59.000Z
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.
Frederick, B.deB. [California Univ., Berkeley, CA (United States)]|[Lawrence Berkeley Lab., CA (United States)
1994-12-01T23:59:59.000Z
Nuclear magnetic resonance (NMR) spectroscopic imaging of {sup 23}Na holds promise as a non-invasive method of mapping Na{sup +} distributions, and for differentiating pools of Na{sup +} ions in biological tissues. However, due to NMR relaxation properties of {sup 23}Na in vivo, a large fraction of Na{sup +} is not visible with conventional NMR imaging methods. An alternate imaging method, based on stochastic excitation and oscillating gradients, has been developed which is well adapted to measuring nuclei with short T{sub 2}. Contemporary NMR imaging techniques have dead times of up to several hundred microseconds between excitation and sampling, comparable to the shortest in vivo {sup 23}Na T{sub 2} values, causing significant signal loss. An imaging strategy based on stochastic excitation has been developed which greatly reduces experiment dead time by reducing peak radiofrequency (RF) excitation power and using a novel RF circuit to speed probe recovery. Continuously oscillating gradients are used to eliminate transient eddy currents. Stochastic {sup 1}H and {sup 23}Na spectroscopic imaging experiments have been performed on a small animal system with dead times as low as 25{mu}s, permitting spectroscopic imaging with 100% visibility in vivo. As an additional benefit, the encoding time for a 32x32x32 spectroscopic image is under 30 seconds. The development and analysis of stochastic NMR imaging has been hampered by limitations of the existing phase demodulation reconstruction technique. Three dimensional imaging was impractical due to reconstruction time, and design and analysis of proposed experiments was limited by the mathematical intractability of the reconstruction method. A new reconstruction method for stochastic NMR based on Fourier interpolation has been formulated combining the advantage of a several hundredfold reduction in reconstruction time with a straightforward mathematical form.
Time dependence of Hawking radiation entropy
Page, Don N., E-mail: profdonpage@gmail.com [Department of Physics, 4-181 CCIS, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)
2013-09-01T23:59:59.000Z
If a black hole starts in a pure quantum state and evaporates completely by a unitary process, the von Neumann entropy of the Hawking radiation initially increases and then decreases back to zero when the black hole has disappeared. Here numerical results are given for an approximation to the time dependence of the radiation entropy under an assumption of fast scrambling, for large nonrotating black holes that emit essentially only photons and gravitons. The maximum of the von Neumann entropy then occurs after about 53.81% of the evaporation time, when the black hole has lost about 40.25% of its original Bekenstein-Hawking (BH) entropy (an upper bound for its von Neumann entropy) and then has a BH entropy that equals the entropy in the radiation, which is about 59.75% of the original BH entropy 4?M{sub 0}{sup 2}, or about 7.509M{sub 0}{sup 2} ? 6.268 × 10{sup 76}(M{sub 0}/M{sub s}un){sup 2}, using my 1976 calculations that the photon and graviton emission process into empty space gives about 1.4847 times the BH entropy loss of the black hole. Results are also given for black holes in initially impure states. If the black hole starts in a maximally mixed state, the von Neumann entropy of the Hawking radiation increases from zero up to a maximum of about 119.51% of the original BH entropy, or about 15.018M{sub 0}{sup 2} ? 1.254 × 10{sup 77}(M{sub 0}/M{sub s}un){sup 2}, and then decreases back down to 4?M{sub 0}{sup 2} = 1.049 × 10{sup 77}(M{sub 0}/M{sub s}un){sup 2}.
CHARYBDIS: A Black Hole Event Generator
C. M. Harris; P. Richardson; B. R. Webber
2003-07-24T23:59:59.000Z
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.
Might black holes reveal their inner secrets?
Ted Jacobson; Thomas P. Sotiriou
2010-06-09T23:59:59.000Z
Black holes harbor a spacetime singularity of infinite curvature, where classical spacetime physics breaks down, and current theory cannot predict what will happen. However, the singularity is invisible from the outside because strong gravity traps all signals, even light, behind an event horizon. In this essay we discuss whether it might be possible to destroy the horizon, if a body is tossed into the black hole so as to make it spin faster and/or have more charge than a certain limit. It turns out that one could expose a "naked" singularity if effects of the body's own gravity can be neglected. We suspect however that such neglect is unjustified.
BLACK HOLE ENTROPY IN HIGHER CURVATURE GRAVITY
TED JACOBSON; GUNGWON KANG; ROBERT C. MYERS
1995-02-27T23:59:59.000Z
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.
How red is a quantum black hole?
Viqar Husain; Oliver Winkler
2005-05-30T23:59:59.000Z
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.
Tachyon Perturbation on Two Dimensional Black Hole
Aniket Basu
2014-07-03T23:59:59.000Z
We study the black hole geometry in the presence of tachyonic perturbations, and solve for the form of allowed tachyonic hair in the presence of back reaction, and for the form of the metric under the assumption that only the metric is perturbed but not the dilaton. We evaluate the Kretschmann scalar and argue that the horizon becomes singular in the presence of tachyons, implying that the black hole has turned into a naked singularity. A form of the allowed tachyon potential emerges as a requirement of self-consistency of our solution.
Chaotic Information Processing by Extremal Black Holes
Axenides, Minos; Nicolis, Stam
2015-01-01T23:59:59.000Z
We review an explicit regularization of the AdS$_2$/CFT$_1$ correspondence, that preserves all isometries of bulk and boundary degrees of freedom. This scheme is useful to characterize the space of the unitary evolution operators that describe the dynamics of the microstates of extremal black holes in four spacetime dimensions. Using techniques from algebraic number theory to evaluate the transition amplitudes, we remark that the regularization scheme expresses the fast quantum computation capability of black holes as well as its chaotic nature.
Physics Beyond the Standard Model: Exotic Leptons and Black Holes at Future Colliders
Christopher M. Harris
2005-02-01T23:59:59.000Z
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.
Microhole Coiled Tubing Bottom Hole Assemblies
Don Macune
2008-06-30T23:59:59.000Z
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.
Mark A. Peletier; Frank Redig; Kiamars Vafayi
2014-03-19T23:59:59.000Z
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.
Plunk, G G
2015-01-01T23:59:59.000Z
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.
Topological black holes in Horava-Lifshitz gravity
Cai Ronggen [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China) and Kavli Institute for Theoretical Physics China (KITPC), Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China); Cao Liming [Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Ohta, Nobuyoshi [Department of Physics, Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan)
2009-07-15T23:59:59.000Z
We find topological (charged) black holes whose horizon has an arbitrary constant scalar curvature 2k in Horava-Lifshitz theory. Without loss of generality, one may take k=1, 0, and -1. The black hole solution is asymptotically anti-de Sitter with a nonstandard asymptotic behavior. Using the Hamiltonian approach, we define a finite mass associated with the solution. We discuss the thermodynamics of the topological black holes and find that the black hole entropy has a logarithmic term in addition to an area term. We find a duality in Hawking temperature between topological black holes in Horava-Lifshitz theory and Einstein's general relativity: the temperature behaviors of black holes with k=1, 0, and -1 in Horava-Lifshitz theory are, respectively, dual to those of topological black holes with k=-1, 0, and 1 in Einstein's general relativity. The topological black holes in Horava-Lifshitz theory are thermodynamically stable.
COSO Geothermal Exploratory Hole No. 1, CGEH No. 1. Completion...
Geothermal Exploratory Hole No. 1, CGEH No. 1. Completion report. (Coso Hot Springs KGRA) Abstract Coso Geothermal Exploratory Hole No. 1 (CGEH No. 1) is the first deep exploratory...
Dynamics of galaxy cores and supermassive black holes
David Merritt
2006-05-02T23:59:59.000Z
Recent work on the dynamical evolution of galactic nuclei containing supermassive black holes is reviewed. Topics include galaxy structural properties; collisionless and collisional equilibria; loss-cone dynamics; and dynamics of binary and multiple supermassive black holes.
Steady and unsteady calibration of multi-hole probes
Johansen, Espen S
1998-01-01T23:59:59.000Z
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...
Performance of conjugate gradient-like algorithms in transient two-phase subchannel analysis
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
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.
Can the fluctuations of a black hole be treated thermodynamically?
Kostyantyn Ropotenko
2008-03-31T23:59:59.000Z
Since the temperature of a typical Schwarzschild black hole is very low, some doubts are raised about whether the fluctuations of the black hole can be treated thermodynamically. It is shown that this is not the case: the thermodynamic fluctuations of a black hole are considerably larger than the corresponding quantum fluctuations. Moreover the ratio of the mean square thermodynamic fluctuation to the corresponding quantum fluctuation can be interpreted as a number of the effective constituents of a black hole.