Geologic interpretation of gravity and magnetic data in the Salida...
interpretation of gravity and magnetic data in the Salida region, Colorado Authors J.E. Case and R.F. Sikora Published U.S. Geological Survey Open-File Report, 1984 Report...
Neutron stars in a perturbative f(R) gravity model with strong magnetic fields
Cheoun, Myung-Ki; Deliduman, Cemsinan; Güngör, Can; Kele?, Vildan; Ryu, C.Y.; Kajino, Toshitaka; Mathews, Grant J. E-mail: cemsinan@msgsu.edu.tr E-mail: kelesvi@itu.edu.tr E-mail: kajino@nao.ac.jp
2013-10-01
In Kaluza-Klein electromagnetism it is natural to associate modified gravity with strong electromagnetic fields. Hence, in this paper we investigate the combined effects of a strong magnetic field and perturbative f(R) gravity on the structure of neutron stars. The effect of an interior strong magnetic field of about 10{sup 17?18} G on the equation of state is derived in the context of a quantum hadrodynamics (QHD) equation of state (EoS) including effects of the magnetic pressure and energy along with occupied Landau levels. Adopting a random orientation of interior field domains, we solve the modified spherically symmetric hydrostatic equilibrium equations derived for a gravity model with f(R) = R+?R{sup 2}. Effects of both the finite magnetic field and the modified gravity are detailed for various values of the magnetic field and the perturbation parameter ? along with a discussion of their physical implications. We show that there exists a parameter space of the modified gravity and the magnetic field strength, in which even a soft equation of state can accommodate a large ( > 2 M{sub s}un) maximum neutron star mass.
Donovan-Ealy, P.F. . Geology Dept.); Hendricks, J.D. )
1992-01-01
The Hopi Buttes volcanic field is located in the Navajo Nation of northeastern Arizona, near the southern margin of the Colorado Plateau. Explosive phreatomagmatic eruptions from late Miocene to mid-Pliocene time produced more than 300 maar-diatremes and deposited limburgite tuffs and tuff breccia and monchiquite dikes, necks and flows within a roughly circular 2,500 km[sup 2] area. The volcanic and volcaniclastic rocks make up the middle member of the Bidahochi Formation, whose lower and upper members are lacustrine and fluvial, respectively. The Bidahochi Formation overlies gently dipping Mesozoic sedimentary rocks exposed in the southwestern portion of the volcanic field. Two significant gravity and magnetic anomalies appear within the Hopi Buttes volcanic field that are unlike the signatures of other Tertiary volcanic fields on the Colorado Plateau. A circular 20 mGal negative gravity anomaly is centered over exposed sedimentary rocks in the southwestern portion of the field. The anomaly may be due to the large volume of low density pyroclastic rocks in the volcanic field and/or extensive brecciation of the underlying strata from the violent maar eruptions. The second significant anomaly is the northeast-trending Holbrook lineament, a 5 km-wide gravity and magnetic lineament that crosses the southeastern part of the volcanic field. The lineament reflects substantial gravity and magnetic decreases of 1.67 mGals/km and 100 gammas/km respectively, to the southeast. Preliminary two-dimensional gravity and magnetic modeling suggests the lineament represents a major Proterozoic crustal boundary and may correlate with one of several Proterozoic faults exposed in the transition zone of central Arizona. Gravity modeling shows a 3--5 km step'' in the Moho near the crustal boundary. The decrease in depth of the Moho to the northwest indicates either movement along the fault or magmatic upwelling beneath the volcanic field.
Blakely, Richard J.; Sherrod, Brian; Weaver, Craig; Wells, Ray E.; Rohay, Alan C.
2014-06-11
Magnetic and gravity data, collected in south-central Washington near the Yakima Fold and Thrust Belt (YFTB) are used to model upper crustal structure, the extent of the late Columbia River Basalt flow named the Ice Harbor member, the vertical conduits (dikes) that the Ice Harbor erupted from, and whether the dikes are offset or affected by faulting on the Wallula Fault zone.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Now which is stronger, gravity or magnetism? What is going on? How do flexible refrigerator magnets work? Get 2 of these magnets, they are often the size of a business card....
Lujan, Richard E. (Santa Fe, NM)
2001-01-01
A mechanical gravity brake that prevents hoisted loads within a shaft from free-falling when a loss of hoisting force occurs. A loss of hoist lifting force may occur in a number of situations, for example if a hoist cable were to break, the brakes were to fail on a winch, or the hoist mechanism itself were to fail. Under normal hoisting conditions, the gravity brake of the invention is subject to an upward lifting force from the hoist and a downward pulling force from a suspended load. If the lifting force should suddenly cease, the loss of differential forces on the gravity brake in free-fall is translated to extend a set of brakes against the walls of the shaft to stop the free fall descent of the gravity brake and attached load.
Ground Gravity Survey At Lightning Dock Geothermal Area (Swanberg...
Basis Examination of geothermal resources of New Mexico Notes detailed gravity and magnetics survey of Lightning Dock to identify burried structures as a source of the thermal...
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Now which is stronger, gravity or magnetism? What is going on? How do flexible refrigerator magnets work? Get two of these magnets, they are often the size of a business card....
Gravity Data for west-central Colorado
Zehner, Richard
2012-04-06
Modeled Bouger Gravity data was extracted from the Pan American Center for Earth and Environmental Studies Gravity Database of the U.S. at http://irpsrvgis08.utep.edu/viewers/Flex/GravityMagnetic/GravityMagnetic_CyberShare/ on 2/29/2012. The downloaded text file was opened in an Excel spreadsheet. This spreadsheet data was then converted into an ESRI point shapefile in UTM Zone 13 NAD27 projection, showing location and gravity (in milligals). This data was then converted to grid and then contoured using ESRI Spatial Analyst. This dataset contains the original spreadsheet data, a point shapefile showing gravity station locations and Bouger gravity, and a line shapefile showing 1 milligal contours. Projection: UTM Zone 13 NAD27 Gravity Contour Shapefile Extent: West -108.366690 East -105.478730 North 40.932318 South 36.961606 Gravity Point Shapefile Extent: West -108.366692 East -105.478847 North 40.932361 South 36.961606 Data from From University of Texas: Pan American Center for Earth and Environmental Studies
Is nonrelativistic gravity possible?
Kocharyan, A. A.
2009-07-15
We study nonrelativistic gravity using the Hamiltonian formalism. For the dynamics of general relativity (relativistic gravity) the formalism is well known and called the Arnowitt-Deser-Misner (ADM) formalism. We show that if the lapse function is constrained correctly, then nonrelativistic gravity is described by a consistent Hamiltonian system. Surprisingly, nonrelativistic gravity can have solutions identical to relativistic gravity ones. In particular, (anti-)de Sitter black holes of Einstein gravity and IR limit of Horava gravity are locally identical.
U.S. Energy Information Administration (EIA) Indexed Site
gravity of 22 degrees or below. Intermediate crudes fall in the range of 22 degrees to 38 degrees API gravity. ASTM: American Society for Testing and Materials. Aviation...
Quantum Field Theory & Gravity
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begin? What is its large scale structure and evolution? How can gravity be unified with quantum mechanics and the Standard Model? Quantum Field Theory, Gravity & Cosmology There...
Ground Gravity Survey At Neal Hot Springs Geothermal Area (U...
survey was completed by MWH Geo-Surveys. Interpretations were made by creating a 3D density inversion map. Gravity and magnetic data were used in siting the first production...
Hofacker, H.B.
1958-09-23
This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.
Polchinski, Joseph [Kavli Institute for Theoretical Physics
2010-09-01
Gauge theories, which describe the particle interactions, are well understood, while quantum gravity leads to many puzzles. Remarkably, in recent years we have learned that these are actually dual, the same system written in different variables. On the one hand, this provides our most precise description of quantum gravity, resolves some long-standing paradoxes, and points to new principles. On the other, it gives a new perspective on strong interactions, with surprising connections to other areas of physics. I describe these ideas, and discuss current and future directions.
Extreme neutron stars from Extended Theories of Gravity
Astashenok, Artyom V.; Capozziello, Salvatore; Odintsov, Sergei D. E-mail: capozziello@na.infn.it
2015-01-01
We discuss neutron stars with strong magnetic mean fields in the framework of Extended Theories of Gravity. In particular, we take into account models derived from f(R) and f(G) extensions of General Relativity where functions of the Ricci curvature invariant R and the Gauss-Bonnet invariant G are respectively considered. Dense matter in magnetic mean field, generated by magnetic properties of particles, is described by assuming a model with three meson fields and baryons octet. As result, the considerable increasing of maximal mass of neutron stars can be achieved by cubic corrections in f(R) gravity. In principle, massive stars with M > 4M{sub ?} can be obtained. On the other hand, stable stars with high strangeness fraction (with central densities ?{sub c} ? 1.5–2.0 GeV/fm{sup 3}) are possible considering quadratic corrections of f(G) gravity. The magnetic field strength in the star center is of order 6–8 × 10{sup 18} G. In general, we can say that other branches of massive neutron stars are possible considering the extra pressure contributions coming from gravity extensions. Such a feature can constitute both a probe for alternative theories and a way out to address anomalous self-gravitating compact systems.
Geometric scalar theory of gravity
Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D.; Moschella, U. E-mail: eduhsb@cbpf.br E-mail: egoulart@cbpf.br E-mail: toniato@cbpf.br
2013-06-01
We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.
Gravity Methods | Open Energy Information
Methods Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Gravity Methods Details Activities (0) Areas (0) Regions (0) NEPA(3) Exploration...
Gravity Techniques | Open Energy Information
in density, such as at fault contacts. 2 Gravity techniques are also applied towards reservoir monitoring for subsidence and mass gain or loss within a geothermal reservoir...
Geologic interpretation of gravity anomalies
Andreyev, B.A.; Klushin, I.G.
1990-04-19
This Russian textbook provides a sufficiently complete and systematic illumination of physico-geologic and mathematical aspect of complex problem of interpretation of gravity anomalies. The rational methods of localization of anomalies are examined in detail. All methods of interpreting gravity anomalies are described which have found successful application in practice. Also given are ideas of some new methods of the interpretation of gravity anomalies, the prospects for further development and industrial testing. Numerous practical examples to interpretation are given. Partial Contents: Bases of gravitational field theory; Physico-geologic bases of gravitational prospecting; Principles of geologic interpretation of gravity anomalies; Conversions and calculations of anomalies; Interpretation of gravity anomalies for bodies of correct geometric form and for bodies of arbitrary form; Geologic interpretation of the results of regional gravitational photographing; Searches and prospecting of oil- and gas-bearing structures and of deposits of ore and nonmetalliferous useful minerals.
Category:Gravity Techniques | Open Energy Information
the following 3 subcategories, out of 3 total. A Airborne Gravity Survey 1 pages G Ground Gravity Survey 1 pages M Microgravity-Hybrid Microgravity 1 pages...
Angular momentum transport via internal gravity waves in evolving stars
Fuller, Jim; Lecoanet, Daniel; Cantiello, Matteo; Brown, Ben
2014-11-20
Recent asteroseismic advances have allowed for direct measurements of the internal rotation rates of many subgiant and red giant stars. Unlike the nearly rigidly rotating Sun, these evolved stars contain radiative cores that spin faster than their overlying convective envelopes, but slower than they would in the absence of internal angular momentum transport. We investigate the role of internal gravity waves in angular momentum transport in evolving low-mass stars. In agreement with previous results, we find that convectively excited gravity waves can prevent the development of strong differential rotation in the radiative cores of Sun-like stars. As stars evolve into subgiants, however, low-frequency gravity waves become strongly attenuated and cannot propagate below the hydrogen-burning shell, allowing the spin of the core to decouple from the convective envelope. This decoupling occurs at the base of the subgiant branch when stars have surface temperatures of T ? 5500 K. However, gravity waves can still spin down the upper radiative region, implying that the observed differential rotation is likely confined to the deep core near the hydrogen-burning shell. The torque on the upper radiative region may also prevent the core from accreting high angular momentum material and slow the rate of core spin-up. The observed spin-down of cores on the red giant branch cannot be totally attributed to gravity waves, but the waves may enhance shear within the radiative region and thus increase the efficacy of viscous/magnetic torques.
Quantum Field Theory & Gravity
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Quantum Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email Bruce Carlsten (505) 667-5657 Email Quantum Field Theory and Gravity at Los Alamos The HEP effort at Los Alamos in this area is actively pursing a number of questions in this area. What is the final state of complete gravitational collapse? What happens at the event horizon? What is dark energy? How did the
Cosmological perturbations in unimodular gravity
Gao, Caixia; Brandenberger, Robert H.; Cai, Yifu; Chen, Pisin E-mail: rhb@hep.physics.mcgill.ca E-mail: chen@slac.stanford.edu
2014-09-01
We study cosmological perturbation theory within the framework of unimodular gravity. We show that the Lagrangian constraint on the determinant of the metric required by unimodular gravity leads to an extra constraint on the gauge freedom of the metric perturbations. Although the main equation of motion for the gravitational potential remains the same, the shift variable, which is gauge artifact in General Relativity, cannot be set to zero in unimodular gravity. This non-vanishing shift variable affects the propagation of photons throughout the cosmological evolution and therefore modifies the Sachs-Wolfe relation between the relativistic gravitational potential and the microwave temperature anisotropies. However, for adiabatic fluctuations the difference between the result in General Relativity and unimodular gravity is suppressed on large angular scales. Thus, no strong constraints on the theory can be derived.
Emergent Horava gravity in graphene
Volovik, G.E.; L. D. Landau Institute for Theoretical Physics, Kosygina 2, 119334 Moscow ; Zubkov, M.A.
2014-01-15
First of all, we reconsider the tight-binding model of monolayer graphene, in which the variations of the hopping parameters are allowed. We demonstrate that the emergent 2D Weitzenbock geometry as well as the emergent U(1) gauge field appear. The emergent gauge field is equal to the linear combination of the components of the zweibein. Therefore, we actually deal with the gauge fixed version of the emergent 2+1 D teleparallel gravity. In particular, we work out the case, when the variations of the hopping parameters are due to the elastic deformations, and relate the elastic deformations with the emergent zweibein. Next, we investigate the tight-binding model with the varying intralayer hopping parameters for the multilayer graphene with the ABC stacking. In this case the emergent 2D Weitzenbock geometry and the emergent U(1) gauge field appear as well, and the emergent low energy effective field theory has the anisotropic scaling. -- Highlights: •The tight-binding model for graphene with varying hopping parameters is considered. •The emergent gravity and emergent gauge fields are derived. •For the case of the multilayer graphene we obtain the analogue of Horava gravity with anisotropic scaling.
Simultaneous measurement of gravity acceleration and gravity gradient with an atom interferometer
Sorrentino, F.; Lien, Y.-H.; Rosi, G.; Tino, G. M.; Bertoldi, A.; Bodart, Q.; Cacciapuoti, L.; Angelis, M. de; Prevedelli, M.
2012-09-10
We demonstrate a method to measure the gravitational acceleration with a dual cloud atom interferometer; the use of simultaneous atom interferometers reduces the effect of seismic noise on the gravity measurement. At the same time, the apparatus is capable of accurate measurements of the vertical gravity gradient. The ability to determine the gravity acceleration and gravity gradient simultaneously and with the same instrument opens interesting perspectives in geophysical applications.
Growth histories in bimetric massive gravity
Berg, Marcus; Buchberger, Igor; Enander, Jonas; Mörtsell, Edvard; Sjörs, Stefan E-mail: igor.buchberger@kau.se E-mail: edvard@fysik.su.se
2012-12-01
We perform cosmological perturbation theory in Hassan-Rosen bimetric gravity for general homogeneous and isotropic backgrounds. In the de Sitter approximation, we obtain decoupled sets of massless and massive scalar gravitational fluctuations. Matter perturbations then evolve like in Einstein gravity. We perturb the future de Sitter regime by the ratio of matter to dark energy, producing quasi-de Sitter space. In this more general setting the massive and massless fluctuations mix. We argue that in the quasi-de Sitter regime, the growth of structure in bimetric gravity differs from that of Einstein gravity.
Airborne Gravity Survey | Open Energy Information
Gravity Techniques Information Provided by Technique Lithology: Distribution of density in the subsurface enables inference of rock type. StratigraphicStructural:...
Ground Gravity Survey | Open Energy Information
Et Al., 2000) Dixie Valley Geothermal Area 1999 2000 Precise Gravimetry and Geothermal Reservoir Management Ground Gravity Survey At Dixie Valley Geothermal Area (Blackwell, Et...
Naked singularities and quantum gravity
Harada, Tomohiro; Iguchi, Hideo; Nakao, Ken-ichi; Singh, T. P.; Tanaka, Takahiro; Vaz, Cenalo
2001-08-15
There are known models of spherical gravitational collapse in which the collapse ends in a naked shell-focusing singularity for some initial data. If a massless scalar field is quantized on the classical background provided by such a star, it is found that the outgoing quantum flux of the scalar field diverges in the approach to the Cauchy horizon. We argue that the semiclassical approximation (i.e., quantum field theory on a classical curved background) used in these analyses ceases to be valid about one Planck time before the epoch of naked singularity formation, because by then the curvature in the central region of the star reaches the Planck scale. It is shown that during the epoch in which the semiclassical approximation is valid, the total emitted energy is about one Planck unit, and is not divergent. We also argue that back reaction in this model does not become important so long as gravity can be treated classically. It follows that the further evolution of the star will be determined by quantum gravitational effects, and without invoking quantum gravity it is not possible to say whether the star radiates away on a short time scale or settles down into a black hole state.
Ground Gravity Survey At Clear Lake Area (Skokan, 1993) | Open...
Ground Gravity Survey At Clear Lake Area (Skokan, 1993) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Clear Lake Area...
A new quasidilaton theory of massive gravity (Journal Article...
Office of Scientific and Technical Information (OSTI)
A new quasidilaton theory of massive gravity Citation Details In-Document Search Title: A new quasidilaton theory of massive gravity We present a new quasidilaton theory of...
Ground Gravity Survey At Coso Geothermal Area (1980) | Open Energy...
Ground Gravity Survey At Coso Geothermal Area (1980) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Coso Geothermal...
Ground Gravity Survey At Crump's Hot Springs Area (DOE GTP) ...
Ground Gravity Survey At Crump's Hot Springs Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Crump's Hot...
Category:Airborne Gravity Survey | Open Energy Information
Category Edit History Category:Airborne Gravity Survey Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Geothermalpower.jpg Looking for the Airborne Gravity Survey...
Ground Gravity Survey At North Brawley Geothermal Area (Biehler...
Ground Gravity Survey At North Brawley Geothermal Area (Biehler, 1964) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At...
Ground Gravity Survey At Cove Fort Area - Vapor (Warpinski, Et...
Ground Gravity Survey At Cove Fort Area - Vapor (Warpinski, Et Al., 2002) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (FURUMOTO...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (FURUMOTO, 1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey...
Ground Gravity Survey At Snake River Plain Region (DOE GTP) ...
Ground Gravity Survey At Snake River Plain Region (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Snake River...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Thomas...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Thomas, 1986) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Broyles...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Broyles, Et Al., 1979) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity...
Integration of Full Tensor Gravity and ZTEM Passive Low Frequency...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments for Simultaneous Data Acquisition Integration of Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments...
Negative Effective Gravity in Water Waves by Periodic Resonator...
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Negative Effective Gravity in Water Waves by Periodic Resonator Arrays Prev Next Title: Negative Effective Gravity in Water Waves by Periodic Resonator Arrays Authors: Hu,...
Asymptotically (anti)-de Sitter solutions in Gauss-Bonnet gravity without a cosmological constant
Dehghani, M.H.
2004-09-15
In this paper I show that one can have asymptotically de Sitter, anti-de Sitter (AdS), and flat solutions in Gauss-Bonnet gravity without a cosmological constant term in field equations. First, I introduce static solutions whose three surfaces at fixed r and t have constant positive (k=1), negative (k=-1), or zero (k=0) curvature. I show that for k={+-}1 one can have asymptotically de Sitter, AdS, and flat spacetimes, while for the case of k=0, one has only asymptotically AdS solutions. Some of these solutions present naked singularities, while some others are black hole or topological black hole solutions. I also find that the geometrical mass of these five-dimensional spacetimes is m+2{alpha}|k|, which is different from the geometrical mass m of the solutions of Einstein gravity. This feature occurs only for the five-dimensional solutions, and is not repeated for the solutions of Gauss-Bonnet gravity in higher dimensions. Second, I add angular momentum to the static solutions with k=0, and introduce the asymptotically AdS charged rotating solutions of Gauss-Bonnet gravity. Finally, I introduce a class of solutions which yields an asymptotically AdS spacetime with a longitudinal magnetic field, which presents a naked singularity, and generalize it to the case of magnetic rotating solutions with two rotation parameters.
Spin-stabilized magnetic levitation without vertical axis of rotation
Romero, Louis (Albuquerque, NM); Christenson, Todd (Albuquerque, NM); Aaronson, Gene (Albuquerque, NM)
2009-06-09
The symmetry properties of a magnetic levitation arrangement are exploited to produce spin-stabilized magnetic levitation without aligning the rotational axis of the rotor with the direction of the force of gravity. The rotation of the rotor stabilizes perturbations directed parallel to the rotational axis.
Quantum gravity and renormalization: The tensor track
Rivasseau, Vincent
2012-06-27
We propose a new program to quantize and renormalize gravity based on recent progress on the analysis of large random tensors. We compare it briefly with other existing approaches.
Gauge natural formulation of conformal gravity
Campigotto, M.; Fatibene, L.
2015-03-15
We consider conformal gravity as a gauge natural theory. We study its conservation laws and superpotentials. We also consider the Mannheim and Kazanas spherically symmetric vacuum solution and discuss conserved quantities associated to conformal and diffeomorphism symmetries.
Bouguer gravity map | Open Energy Information
LibraryAdd to library Map: Bouguer gravity mapInfo GraphicMapChart Cartographers J. Behrendt and L. Bajwa Organization U.S. Geological Survey Published U.S. Geological...
Constraints on Covariant Horava-Lifshitz Gravity from frame-dragging experiment
Radicella, Ninfa; Lambiase, Gaetano; Parisi, Luca; Vilasi, Gaetano E-mail: lambiase@sa.infn.it E-mail: vilasi@sa.infn.it
2014-12-01
The effects of Horava-Lifshitz corrections to the gravito-magnetic field are analyzed. Solutions in the weak field, slow motion limit, referring to the motion of a satellite around the Earth are considered. The post-newtonian paradigm is used to evaluate constraints on the Horava-Lifshitz parameter space from current satellite and terrestrial experiments data. In particular, we focus on GRAVITY PROBE B, LAGEOS and the more recent LARES mission, as well as a forthcoming terrestrial project, GINGER.
Gravity waves from cosmic bubble collisions
Salem, Michael P.; Saraswat, Prashant; Shaghoulian, Edgar E-mail: ps88@stanford.edu
2013-02-01
Our local Hubble volume might be contained within a bubble that nucleated in a false vacuum with only two large spatial dimensions. We study bubble collisions in this scenario and find that they generate gravity waves, which are made possible in this context by the reduced symmetry of the global geometry. These gravity waves would produce B-mode polarization in the cosmic microwave background, which could in principle dominate over the inflationary background.
Measuring antimatter gravity with muonium
Kaplan, Daniel M.; Kirch, Klaus; Mancini, Derrick; Phillips, James D.; Phillips, Thomas J.; Roberts, Thomas J.; Terry, Jeff; Bravina, L.; Foka, Y.; Kabana, S.
2015-05-29
The gravitational acceleration of antimatter, ¯g, has never been directly measured and could bear importantly on our understanding of gravity, the possible existence of a fifth force, and the nature and early history of the universe. Only two avenues for such a measurement appear to be feasible: antihydrogen and muonium. The muonium measurement requires a novel, monoenergetic, low-velocity, horizontal muonium beam directed at an atom interferometer. The precision three-grating interferometer can be produced in silicon nitride or ultrananocrystalline diamond using state-of-the-art nanofabrication. The required precision alignment and calibration at the picometer level also appear to be feasible. With 100 nm grating pitch, a 10% measurement of ¯g can be made using some months of surface-muon beam time, and a 1% or better measurement with a correspondingly larger exposure. This could constitute the first gravitational measurement of leptonic matter, of 2nd-generation matter and, possibly, the first measurement of the gravitational acceleration of antimatter.
Measuring antimatter gravity with muonium
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Kaplan, Daniel M.; Kirch, Klaus; Mancini, Derrick; Phillips, James D.; Phillips, Thomas J.; Roberts, Thomas J.; Terry, Jeff; Bravina, L.; Foka, Y.; Kabana, S.
2015-05-29
The gravitational acceleration of antimatter, Â¯g, has never been directly measured and could bear importantly on our understanding of gravity, the possible existence of a fifth force, and the nature and early history of the universe. Only two avenues for such a measurement appear to be feasible: antihydrogen and muonium. The muonium measurement requires a novel, monoenergetic, low-velocity, horizontal muonium beam directed at an atom interferometer. The precision three-grating interferometer can be produced in silicon nitride or ultrananocrystalline diamond using state-of-the-art nanofabrication. The required precision alignment and calibration at the picometer level also appear to be feasible. With 100 nmmoreÂ Â» grating pitch, a 10% measurement of Â¯g can be made using some months of surface-muon beam time, and a 1% or better measurement with a correspondingly larger exposure. This could constitute the first gravitational measurement of leptonic matter, of 2nd-generation matter and, possibly, the first measurement of the gravitational acceleration of antimatter.Â«Â less
Nonderivative modified gravity: a classification
Comelli, D.; Nesti, F.; Pilo, L. E-mail: fabrizio.nesti@irb.hr
2014-11-01
We analyze the theories of gravity modified by a generic nonderivative potential built from the metric, under the minimal requirement of unbroken spatial rotations. Using the canonical analysis, we classify the potentials V according to the number of degrees of freedom (DoF) that propagate at the nonperturbative level. We then compare the nonperturbative results with the perturbative DoF propagating around Minkowski and FRW backgrounds. A generic V implies 6 propagating DoF at the non-perturbative level, with a ghost on Minkowski background. There exist potentials which propagate 5 DoF, as already studied in previous works. Here, no V with unbroken rotational invariance admitting 4 DoF is found. Theories with 3 DoF turn out to be strongly coupled on Minkowski background. Finally, potentials with only the 2 DoF of a massive graviton exist. Their effect on cosmology is simply equivalent to a cosmological constant. Potentials with 2 or 5 DoF and explicit time dependence appear to be a further viable possibility.
Seymour, P.
1986-01-01
This book deals with the cosmic magnetism in a non-mathematical way. It uses Faraday's very powerful and highly pictorial concept of lines of magnetic force and their associated physical properties to explain the structure and behavior of magnetic fields in extraterrestrial objects. Contents include: forces of nature; magnetic field of earth; solar and interplanetary magnetic fields; magnetic fields in the solar system; stars and pulsars; and magnetic fields of the milky way and other galaxies.
Massive gravity wrapped in the cosmic web
Shim, Junsup; Lee, Jounghun; Li, Baojiu E-mail: jounghun@astro.snu.ac.kr
2014-03-20
We study how the filamentary pattern of the cosmic web changes if the true gravity deviates from general relativity (GR) on a large scale. The f(R) gravity, whose strength is controlled to satisfy the current observational constraints on the cluster scale, is adopted as our fiducial model and a large, high-resolution N-body simulation is utilized for this study. By applying the minimal spanning tree algorithm to the halo catalogs from the simulation at various epochs, we identify the main stems of the rich superclusters located in the most prominent filamentary section of the cosmic web and determine their spatial extents per member cluster to be the degree of their straightness. It is found that the f(R) gravity has the effect of significantly bending the superclusters and that the effect becomes stronger as the universe evolves. Even in the case where the deviation from GR is too small to be detectable by any other observables, the degree of the supercluster straightness exhibits a conspicuous difference between the f(R) and the GR models. Our results also imply that the supercluster straightness could be a useful discriminator of f(R) gravity from the coupled dark energy since it is shown to evolve differently between the two models. As a final conclusion, the degree of the straightness of the rich superclusters should provide a powerful cosmological test of large scale gravity.
Astrophysical black holes in screened modified gravity
Davis, Anne-Christine; Jha, Rahul; Muir, Jessica; Gregory, Ruth E-mail: r.a.w.gregory@durham.ac.uk E-mail: jlmuir@umich.edu
2014-08-01
Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied in laboratory, cosmological, and astrophysical contexts. In this paper, we present a preliminary investigation into whether additional constraints can be provided by studying these scalar fields around black holes. By looking at the properties of a static, spherically symmetric black hole, we find that the presence of a non-uniform matter distribution induces a non-constant scalar profile in chameleon and dilaton, but not necessarily symmetron gravity. An order of magnitude estimate shows that the effects of these profiles on in-falling test particles will be sub-leading compared to gravitational waves and hence observationally challenging to detect.
Charged black holes in generalized teleparallel gravity
Rodrigues, M.E.; Houndjo, M.J.S.; Tossa, J.; Momeni, D.; Myrzakulov, R. E-mail: sthoundjo@yahoo.fr E-mail: d.momeni@yahoo.com
2013-11-01
In this paper we investigate charged static black holes in 4D for generalized teleparallel models of gravity, based on torsion as the geometric object for describing gravity according to the equivalence principle. As a motivated idea, we introduce a set of non-diagonal tetrads and derive the full system of non linear differential equations. We prove that the common Schwarzschild gauge is applicable only when we study linear f(T) case. We reobtain the Reissner-Nordstrom-de Sitter (or RN-AdS) solution for the linear case of f(T) and perform a parametric cosmological reconstruction for two nonlinear models. We also study in detail a type of the no-go theorem in the framework of this modified teleparallel gravity.
Quantum gravity effects in the Kerr spacetime
Reuter, M.; Tuiran, E.
2011-02-15
We analyze the impact of the leading quantum gravity effects on the properties of black holes with nonzero angular momentum by performing a suitable renormalization group improvement of the classical Kerr metric within quantum Einstein gravity. In particular, we explore the structure of the horizons, the ergosphere, and the static limit surfaces as well as the phase space available for the Penrose process. The positivity properties of the effective vacuum energy-momentum tensor are also discussed and the 'dressing' of the black hole's mass and angular momentum are investigated by computing the corresponding Komar integrals. The pertinent Smarr formula turns out to retain its classical form. As for their thermodynamical properties, a modified first law of black-hole thermodynamics is found to be satisfied by the improved black holes (to second order in the angular momentum); the corresponding Bekenstein-Hawking temperature is not proportional to the surface gravity.
Differential geometry, Palatini gravity and reduction
Capriotti, S.
2014-01-15
The present article deals with a formulation of the so called (vacuum) Palatini gravity as a general variational principle. In order to accomplish this goal, some geometrical tools related to the geometry of the bundle of connections of the frame bundle LM are used. A generalization of Lagrange-Poincaré reduction scheme to these types of variational problems allows us to relate it with the Einstein-Hilbert variational problem. Relations with some other variational problems for gravity found in the literature are discussed.
Ground Gravity Survey At Neal Hot Springs Geothermal Area (Colwell...
and a nearby absolute gravity benchmark was tied in. Gravity data indicated a high density region in-between lower density regions to the east and west. The high density region...
The inverse-square law and quantum gravity
Nieto, M.M.; Goldman, T.; Hughes, R.J.
1988-01-01
This paper briefly discusses a modification to central potential of gravity when antimatter is involved and the possible existence of quantum gravity and a fifth force of nature. 1 ref. (LSP)
Ground Gravity Survey At Baltazor Hot Springs Area (Isherwood...
(Fig. 2) shows a gravity low within the valley area that presumably is related to low-density Cenozoic sediments. The steep gravity gradient along the east side of the valley...
Zero-Gravity Centrifugal Force | GE Global Research
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
to create centrifugal force create its on gravity? Example if you were spinning a iron ball in space, just as the earth spins, does the iron ball create its on gravity? scott...
Ultrasonic hydrometer. [Specific gravity of electrolyte
Swoboda, C.A.
1982-03-09
The disclosed ultrasonic hydrometer determines the specific gravity (density) of the electrolyte of a wet battery, such as a lead-acid battery. The hydrometer utilizes a transducer that when excited emits an ultrasonic impulse that traverses through the electrolyte back and forth between spaced sonic surfaces. The transducer detects the returning impulse, and means measures the time t between the initial and returning impulses. Considering the distance d between the spaced sonic surfaces and the measured time t, the sonic velocity V is calculated with the equation V = 2d/t. The hydrometer also utilizes a thermocouple to measure the electrolyte temperature. A hydrometer database correlates three variable parameters including sonic velocity in and temperature and specific gravity of the electrolyte, for temperature values between 0 and 40/sup 0/C and for specific gravity values between 1.05 and 1.30. Upon knowing two parameters (the calculated sonic velocity and the measured temperature), the third parameter (specific gravity) can be uniquely found in the database. The hydrometer utilizes a microprocessor for data storage and manipulation.
Ground Magnetic Data for west-central Colorado
Zehner, Richard
2012-03-08
Ground Magnetic Data for west-central Colorado Modeled ground magnetic data was extracted from the Pan American Center for Earth and Environmental Studies database at http://irpsrvgis08.utep.edu/viewers/Flex/GravityMagnetic/GravityMagnetic_CyberShare/ on 2/29/2012. The downloaded text file was then imported into an Excel spreadsheet. This spreadsheet data was converted into an ESRI point shapefile in UTM Zone 13 NAD27 projection, showing location and magnetic field strength in nano-Teslas. This point shapefile was then interpolated to an ESRI grid using an inverse-distance weighting method, using ESRI Spatial Analyst. The grid was used to create a contour map of magnetic field strength. This dataset includes the raw spreadsheet data, an ESRI point shapefile showing magnetic sample locations and magnetic field strength, and an ESRI line shapefile showing magnetic contours. Projection: UTM Zone 13 NAD27 Magnetic Contour Shapefile Extent: West -108.698836 East -105.283977 North 41.048206 South 36.950086 Magnetic Point Shapefile Extent: West -108.698832 East -105.283908 North 41.048142 South 36.950086
Revised API Gravity ranges of EIA-182 Crude Streams
Gasoline and Diesel Fuel Update (EIA)
API Gravity Ranges of Selected Crude Streams, EIA-182 Gravity 20 or less Alabama Heavy Ca - Coalinga Ca - Cymric Ca - Kern River Ca - Lost Hills Ca - Midway-Sunset Ca OCS - Hondo Ca OCS - Pescado Ca - Wilmington Mississippi Baxterville Gravity 20.1 to 25.0 Ca - Belridge South West Central TX Gravity 25.1 to 30.0 Alaska North Slope Wy Sour Gravity 30.1 to 35.0 Alaska South GC - Eugene Island GC - Heavy Louisiana Sweet (HLS) GC - Hoops Blend GC - Mars Blend La - Louisiana South Mix Montana Sour
Junction conditions in extended Teleparallel gravities
De la Cruz-Dombriz, Álvaro; Dunsby, Peter K.S.; Sáez-Gómez, Diego E-mail: peter.dunsby@uct.ac.za
2014-12-01
In the context of extended Teleparallel gravity theories, we address the issue of junction conditions required to guarantee the correct matching of different regions of spacetime. In the absence of shells/branes, these conditions turn out to be more restrictive than their counterparts in General Relativity as in other extended theories of gravity. In fact, the general junction conditions on the matching hypersurfaces depend on the underlying theory and a new condition on the induced tetrads in order to avoid delta-like distributions in the field equations. This result imposes strict consequences on the viability of standard solutions such as the Einstein-Straus-like construction. We find that the continuity of the scalar torsion is required in order to recover the usual General Relativity results.
Gravity controlled anti-reverse rotation device
Dickinson, Robert J. (Shaler Township, Allegheny County, PA); Wetherill, Todd M. (Lower Burrell, PA)
1983-01-01
A gravity assisted anti-reverse rotation device for preventing reverse rotation of pumps and the like. A horizontally mounted pawl is disposed to mesh with a fixed ratchet preventing reverse rotation when the pawl is advanced into intercourse with the ratchet by a vertically mounted lever having a lumped mass. Gravitation action on the lumped mass urges the pawl into mesh with the ratchet, while centrifugal force on the lumped mass during forward, allowed rotation retracts the pawl away from the ratchet.
Regulation of flexible arms under gravity
De Luca, A.; Siciliano, B.
1993-08-01
A simple controller is presented for the regulation problem of robot arms with flexible links under gravity. It consists of a joint PD feedback plus a constant feedforward. Global asymptotic stability of the reference equilibrium state is shown under a structural assumption about link elasticity and a mild condition on the proportional gain. The result holds also in the absence of internal damping of the flexible arm. A numerical case study is presented.
Neutron stars as laboratories for gravity physics
Deliduman, Cemsinan
2014-01-01
We study the structure of neutron stars in R+?R² gravity model with perturbative method. We obtain mass-radius relations for four representative equations of state (EoS). We find that, for |?|~10? cm², the results differ substantially from the results of general relativity. The effects of modified gravity are seen as mimicking a stiff or soft EoS for neutron stars depending upon whether ? is negative or positive, respectively. Some of the soft EoS that are excluded within the framework of general relativity can be reconciled for certain values of ? of this order with the 2 solar mass neutron star recently observed. Indeed, if the EoS is ever established to be soft, modified gravity of the sort studied here may be required to explain neutron star masses as large as 2 M{sub ?}. The associated length scale ?(?)~10? cm is of the order of the the typical radius of neutron stars implying that this is the smallest value we could find by using neutron stars as a probe. We thus conclude that the true value of ? is most likely much smaller than 10? cm².
Cosmology in general massive gravity theories
Comelli, D.; Nesti, F.; Pilo, L. E-mail: fabrizio.nesti@aquila.infn.it
2014-05-01
We study the cosmological FRW flat solutions generated in general massive gravity theories. Such a model are obtained adding to the Einstein General Relativity action a peculiar non derivative potentials, function of the metric components, that induce the propagation of five gravitational degrees of freedom. This large class of theories includes both the case with a residual Lorentz invariance as well as the case with rotational invariance only. It turns out that the Lorentz-breaking case is selected as the only possibility. Moreover it turns out that that perturbations around strict Minkowski or dS space are strongly coupled. The upshot is that even though dark energy can be simply accounted by massive gravity modifications, its equation of state w{sub eff} has to deviate from -1. Indeed, there is an explicit relation between the strong coupling scale of perturbations and the deviation of w{sub eff} from -1. Taking into account current limits on w{sub eff} and submillimiter tests of the Newton's law as a limit on the possible strong coupling scale, we find that it is still possible to have a weakly coupled theory in a quasi dS background. Future experimental improvements on short distance tests of the Newton's law may be used to tighten the deviation of w{sub eff} form -1 in a weakly coupled massive gravity theory.
Gravity dual of metastable dynamical supersymmetry breaking (Journal
Office of Scientific and Technical Information (OSTI)
Article) | SciTech Connect Gravity dual of metastable dynamical supersymmetry breaking Citation Details In-Document Search Title: Gravity dual of metastable dynamical supersymmetry breaking Metastable, supersymmetry-breaking configurations can be created in flux geometries by placing antibranes in warped throats. Via gauge/gravity duality, such configurations should have an interpretation as supersymmetry-breaking states in the dual field theory. In this paper, we perturbatively determine
A Gravity Dual of Metastable Dynamical Supersymmetry Breaking (Journal
Office of Scientific and Technical Information (OSTI)
Article) | SciTech Connect A Gravity Dual of Metastable Dynamical Supersymmetry Breaking Citation Details In-Document Search Title: A Gravity Dual of Metastable Dynamical Supersymmetry Breaking Metastable, supersymmetry-breaking configurations can be created in flux geometries by placing antibranes in warped throats. Via gauge/gravity duality, such configurations should have an interpretation as supersymmetry-breaking states in the dual field theory. In this paper, we perturbatively
Ground Gravity Survey At Roosevelt Hot Springs Geothermal Area...
Unknown Exploration Basis Faulder 1991 Conceptual Geological Model compilation and literature review of the Roosevelt Hot Springs Geothermal Area. Notes Gravity modeling and...
Ground Gravity Survey At San Francisco Volcanic Field Area (Warpinski...
Francisco Volcanic Field Area (Warpinski, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At San Francisco...
Category:Ground Gravity Survey | Open Energy Information
Apps Datasets Community Login | Sign Up Search Category Edit History Category:Ground Gravity Survey Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home...
Lorentz Invariant phenomenological model of quantum gravity: A minimalistic presentation
Bonder, Yuri
2012-08-24
The purpose of this paper is to give a minimalistic and self-contained presentation of a Lorentz Invariant phenomenological model of Quantum Gravity.
Ground Gravity Survey At Under Steamboat Springs Area (Warpinski...
Finally, the gravity survey also shows anomalies that correlate with the seismic and microseismic data. All of these results will be integrated to obtain the most probable...
Gravity Survey of the Carson Sink - Data and Maps
Faulds, James E.
2013-12-31
A detailed gravity survey was carried out for the entire Carson Sink in western Nevada (Figure 1) through a subcontract to Zonge Engineering, Inc. The Carson Sink is a large composite basin containing three known, blind highâ€temperature geothermal systems (Fallon Airbase, Stillwater, and Soda Lake). This area was chosen for a detailed gravity survey in order to characterize the gravity signature of the known geothermal systems and to identify other potential blind systems based on the structural setting indicated by the gravity data. Data: Data were acquired at approximately 400, 800, and 1600 meter intervals for a total of 1,243 stations. The project location and station location points are presented in Figure 14. The station distribution for this survey was designed to complete regional gravity coverage in the Carson Sink area without duplication of available public and private gravity coverage. Gravity data were acquired using a Scintrex CGâ€5 gravimeter and a LaCoste and Romberg (L&R) Modelâ€G gravimeter. The CGâ€5 gravity meter has a reading resolution of 0.001 milligals and a typical repeatability of less than 0.005 milligals. The L&R gravity meter has a reading resolution of 0.01 milligals and a typical repeatability of 0.02 milligals. The basic processing of gravimeter readings to calculate through to the Complete Bouguer Anomaly was made using the Gravity and Terrain Correction software version 7.1 for Oasis Montaj by Geosoft LTD. Results: The gravity survey of the Carson Sink yielded the following products. Project location and station location map (Figure 14). Complete Bouguer Anomaly @ 2.67 gm/cc reduction density. Gravity Complete Bouguer Anomaly at 2.50 g/cc Contour Map (Figure 15). Gravity Horizontal Gradient Magnitude Shaded Color Contour Map. Gravity 1st Vertical Derivative Color Contour Map. Interpreted Depth to Mesozoic Basement (Figure 16), incorporating drillâ€hole intercept values. Preliminary Interpretation of Results: The Carson Sink is a complex composite basin with several major depocenters (Figures 15 and 16). Major depocenters are present in the southâ€central, eastâ€central, and northeastern parts of the basin. The distribution of gravity anomalies suggests a complex pattern of faulting in the subsurface of the basin, with many fault terminations, stepâ€overs, and accommodation zones. The pattern of faulting implies that other, previously undiscovered blind geothermal systems are likely in the Carson Sink. The gravity survey was completed near the end of this project. Thus, more thorough analysis of the data and potential locations of blind geothermal systems is planned for future work.
Ground Gravity Survey At Truckhaven Area (Warpinski, Et Al.,...
2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Truckhaven Area (Warpinski, Et Al., 2004) Exploration Activity...
Ground Gravity Survey At Lake City Hot Springs Area (Warpinski...
Exploration Activity Details Location Lake City Hot Springs Area Exploration Technique Ground Gravity Survey Activity Date Usefulness not indicated DOE-funding Unknown Notes The...
Ground Gravity Survey At Kilauea East Rift Geothermal Area (Leslie...
of the seaward extension of the ERZ. Gravity measurements of Puna Ridge show a high density anomaly at depth which corresponds to high velocity data obtained from seismic...
Ground Gravity Survey (Nannini, 1986) | Open Energy Information
depth inside the sedimentary formations of the basement and often present a negative density contrast when compared to the latter. Gravity could help to identify these bodies by...
Ground Gravity Survey At Rio Grande Rift Region (Aiken & Ander...
DOE-funding Unknown References Carlos L.V. Aiken, Mark E. Ander (1981) A Regional Strategy For Geothermal Exploration With Emphasis On Gravity And Magnetotellurics Additional...
Ground Gravity Survey At Blue Mountain Geothermal Area (Fairbank...
search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Blue Mountain Geothermal Area (Fairbank Engineering Ltd, 2003) Exploration Activity Details...
Ground Gravity Survey At Chocolate Mountains Area (Alm, Et Al...
Chocolate Mountains Area (Alm, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Chocolate Mountains Area...
Ground Gravity Survey At Coso Geothermal Area (1990) | Open Energy...
(1990) Exploration Activity Details Location Coso Geothermal Area Exploration Technique Ground Gravity Survey Activity Date 1990 Usefulness not indicated DOE-funding Unknown...
Bouguer gravity anomalies, depth to bedrock, and shallow temperature...
Bouguer gravity anomalies, depth to bedrock, and shallow temperature in the Humboldt House geothermal area, Pershing County, Nevada Jump to: navigation, search OpenEI Reference...
A gravity model for the Coso geothermal area, California | Open...
Most of the gravity variations can be explained by two lithologic units: (1) low density wedges of Quarternary alluvium with interbedded thin basalts (2.4 gcmsup 3)...
Ground Gravity Survey At Newberry Caldera Area (DOE GTP) | Open...
Newberry Caldera Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Newberry Caldera Area (DOE GTP)...
Ground Gravity Survey At Mcgee Mountain Area (DOE GTP) | Open...
Mcgee Mountain Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Mcgee Mountain Area (DOE GTP) Exploration...
Ground Gravity Survey At Walker Lake Valley Area (Shoffner, Et...
N. Hinz, A. Sabin, M. Lazaro, S. Alm (2010) Understanding Fault Characteristics And Sediment Depth For Geothermal Exploration Using 3D Gravity Inversion In Walker Valley, Nevada...
Ground Gravity Survey At Under Steamboat Springs Area (Warpinski...
Ground Gravity Survey Activity Date Usefulness useful DOE-funding Unknown Notes Update to Warpinski, et al., 2002 References N. R. Warpinski, A. R. Sattler, R. Fortuna, D....
Ground Gravity Survey At Raft River Geothermal Area (1978) |...
search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Raft River Geothermal Area (1978) Exploration Activity Details Location Raft River...
Perturbations of nested branes with induced gravity
Sbisà, Fulvio; Koyama, Kazuya E-mail: kazuya.koyama@port.ac.uk
2014-06-01
We study the behaviour of weak gravitational fields in models where a 4D brane is embedded inside a 5D brane equipped with induced gravity, which in turn is embedded in a 6D spacetime. We consider a specific regularization of the branes internal structures where the 5D brane can be considered thin with respect to the 4D one. We find exact solutions corresponding to pure tension source configurations on the thick 4D brane, and study perturbations at first order around these background solutions. To perform the perturbative analysis, we adopt a bulk-based approach and we express the equations in terms of gauge invariant and master variables using a 4D scalar-vector-tensor decomposition. We then propose an ansatz on the behaviour of the perturbation fields when the thickness of the 4D brane goes to zero, which corresponds to configurations where gravity remains finite everywhere in the thin limit of the 4D brane. We study the equations of motion using this ansatz, and show that they give rise to a consistent set of differential equations in the thin limit, from which the details of the internal structure of the 4D brane disappear. We conclude that the thin limit of the ''ribbon'' 4D brane inside the (already thin) 5D brane is well defined (at least when considering first order perturbations around pure tension configurations), and that the gravitational field on the 4D brane remains finite in the thin limit. We comment on the crucial role of the induced gravity term on the 5D brane.
Testing chameleon gravity with the Coma cluster
Terukina, Ayumu; Yamamoto, Kazuhiro; Lombriser, Lucas; Bacon, David; Koyama, Kazuya; Nichol, Robert C. E-mail: lucas.lombriser@port.ac.uk E-mail: david.bacon@port.ac.uk E-mail: bob.nichol@port.ac.uk
2014-04-01
We propose a novel method to test the gravitational interactions in the outskirts of galaxy clusters. When gravity is modified, this is typically accompanied by the introduction of an additional scalar degree of freedom, which mediates an attractive fifth force. The presence of an extra gravitational coupling, however, is tightly constrained by local measurements. In chameleon modifications of gravity, local tests can be evaded by employing a screening mechanism that suppresses the fifth force in dense environments. While the chameleon field may be screened in the interior of the cluster, its outer region can still be affected by the extra force, introducing a deviation between the hydrostatic and lensing mass of the cluster. Thus, the chameleon modification can be tested by combining the gas and lensing measurements of the cluster. We demonstrate the operability of our method with the Coma cluster, for which both a lensing measurement and gas observations from the X-ray surface brightness, the X-ray temperature, and the Sunyaev-Zel'dovich effect are available. Using the joint observational data set, we perform a Markov chain Monte Carlo analysis of the parameter space describing the different profiles in both the Newtonian and chameleon scenarios. We report competitive constraints on the chameleon field amplitude and its coupling strength to matter. In the case of f(R) gravity, corresponding to a specific choice of the coupling, we find an upper bound on the background field amplitude of |f{sub R0}| < 6 × 10{sup ?5}, which is currently the tightest constraint on cosmological scales.
Massive gravity on de Sitter and unique candidate for partially massless gravity
Rham, Claudia de; Renaux-Petel, Sébastien E-mail: srenaux@lpthe.jussieu.fr
2013-01-01
We derive the decoupling limit of Massive Gravity on de Sitter in an arbitrary number of space-time dimensions d. By embedding d-dimensional de Sitter into d+1-dimensional Minkowski, we extract the physical helicity-1 and helicity-0 polarizations of the graviton. The resulting decoupling theory is similar to that obtained around Minkowski. We take great care at exploring the partially massless limit and define the unique fully non-linear candidate theory that is free of the helicity-0 mode in the decoupling limit, and which therefore propagates only four degrees of freedom in four dimensions. In the latter situation, we show that a new Vainshtein mechanism is at work in the limit m{sup 2} ? 2H{sup 2} which decouples the helicity-0 mode when the parameters are different from that of partially massless gravity. As a result, there is no discontinuity between massive gravity and its partially massless limit, just in the same way as there is no discontinuity in the massless limit of massive gravity. The usual bounds on the graviton mass could therefore equivalently well be interpreted as bounds on m{sup 2}?2H{sup 2}. When dealing with the exact partially massless parameters, on the other hand, the symmetry at m{sup 2} = 2H{sup 2} imposes a specific constraint on matter. As a result the helicity-0 mode decouples without even the need of any Vainshtein mechanism.
A new quasidilaton theory of massive gravity
Mukohyama, Shinji
2014-12-01
We present a new quasidilaton theory of Poincare invariant massive gravity, based on the recently proposed framework of matter coupling that makes it possible for the kinetic energy of the quasidilaton scalar to couple to both physical and fiducial metrics simultaneously. We find a scaling-type exact solution that expresses a self-accelerating de Sitter universe, and then analyze linear perturbations around it. It is shown that in a range of parameters all physical degrees of freedom have non-vanishing quadratic kinetic terms and are stable in the subhorizon limit, while the effective Newton's constant for the background is kept positive.
A high frequency resonance gravity gradiometer
Bagaev, S. N.; Kvashnin, N. L.; Skvortsov, M. N.; Bezrukov, L. B.; Krysanov, V. A.; Oreshkin, S. I.; Motylev, A. M.; Popov, S. M.; Samoilenko, A. A.; Yudin, I. S.; Rudenko, V. N.
2014-06-15
A new setup OGRAN—the large scale opto-acoustical gravitational detector is described. As distinguished from known gravitational bar detectors it uses the optical interferometrical readout for registering weak variations of gravity gradient at the kilohetz frequency region. At room temperature, its sensitivity is limited only by the bar Brownian noise at the bandwidth close to 100 Hz. It is destined for a search for rare events—gravitational pulses coincident with signals of neutrino scintillator (BUST) in the deep underground of Baksan Neutrino Observatory of INR RAS.
Harko, Tiberiu; Lobo, Francisco S.N.; Otalora, G.; Saridakis, Emmanuel N. E-mail: flobo@cii.fc.ul.pt
2014-12-01
We present an extension of f(T) gravity, allowing for a general coupling of the torsion scalar T with the trace of the matter energy-momentum tensor T. The resulting f(T,T) theory is a new modified gravity, since it is different from all the existing torsion or curvature based constructions. Applied to a cosmological framework, it leads to interesting phenomenology. In particular, one can obtain a unified description of the initial inflationary phase, the subsequent non-accelerating, matter-dominated expansion, and then the transition to a late-time accelerating phase. Additionally, the effective dark energy sector can be quintessence or phantom-like, or exhibit the phantom-divide crossing during the evolution. Moreover, in the far future the universe results either to a de Sitter exponential expansion, or to eternal power-law accelerated expansions. Finally, a detailed study of the scalar perturbations at the linear level reveals that f(T,T) cosmology can be free of ghosts and instabilities for a wide class of ansatzes and model parameters.
Kerns, J.A.; Stone, R.R.; Fabyan, J.
1987-10-06
A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines. 3 figs.
Kerns, John A. (Livermore, CA); Stone, Roger R. (Walnut Creek, CA); Fabyan, Joseph (Livermore, CA)
1987-01-01
A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.
Disformal transformations, veiled General Relativity and Mimetic Gravity
Deruelle, Nathalie; Rua, Josephine E-mail: rua@cbpf.br
2014-09-01
In this Note we show that Einstein's equations for gravity are generically invariant under ''disformations''. We also show that the particular subclass when this is not true yields the equations of motion of ''Mimetic Gravity''. Finally we give the ''mimetic'' generalization of the Schwarzschild solution.
Bimetric gravity doubly coupled to matter: theory and cosmological implications
Akrami, Yashar; Koivisto, Tomi S.; Mota, David F.; Sandstad, Marit E-mail: t.s.koivisto@astro.uio.no E-mail: marit.sandstad@astro.uio.no
2013-10-01
A ghost-free theory of gravity with two dynamical metrics both coupled to matter is shown to be consistent and viable. Its cosmological implications are studied, and the models, in particular in the context of partially massless gravity, are found to explain the cosmic acceleration without resorting to dark energy.
Massive gravitational waves in Chern-Simons modified gravity
Myung, Yun Soo; Moon, Taeyoon E-mail: tymoon@inje.ac.kr
2014-10-01
We consider the nondynamical Chern-Simons (nCS) modified gravity, which is regarded as a parity-odd theory of massive gravity in four dimensions. We first find polarization modes of gravitational waves for Î¸=x/Î¼ in nCS modified gravity by using the Newman-Penrose formalism where the null complex tetrad is necessary to specify gravitational waves. We show that in the Newmanâ€“Penrose formalism, the number of polarization modes is one in addition to an unspecified Î¨{sub 4}, implying three degrees of freedom for Î¸=x/Î¼. This compares with two for a canonical embedding of Î¸=t/Î¼. Also, if one introduces the Ricci tensor formalism to describe a massive graviton arising from the nCS modified gravity, one finds one massive mode after making second-order wave equations, which is compared to five found from the parity-even Einsteinâ€“Weyl gravity.
Passive magnetic bearing element with minimal power losses
Post, Richard F.
1998-01-01
Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in U.S. Patent No. 5,495,221 entitled "Dynamically Stable Magnetic Suspension/Bearing System." The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity.
Passive magnetic bearing element with minimal power losses
Post, R.F.
1998-12-08
Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in US Patent No. 5,495,221 entitled ``Dynamically Stable Magnetic Suspension/Bearing System.`` The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity. 8 figs.
Ground Gravity Survey At Cove Fort Area (Warpinski, Et Al., 2002...
Ground Gravity Survey At Cove Fort Area (Warpinski, Et Al., 2002) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Cove...
Ground Gravity Survey At Hot Pot Area (DOE GTP) | Open Energy...
Ground Gravity Survey At Hot Pot Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Hot Pot Area (DOE GTP)...
Ground Gravity Survey At Fort Bliss Area (DOE GTP) | Open Energy...
Ground Gravity Survey At Fort Bliss Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Fort Bliss Area (DOE...
Ground Gravity Survey At New River Area (DOE GTP) | Open Energy...
Ground Gravity Survey At New River Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At New River Area (DOE...
Ground Gravity Survey At Glass Buttes Area (DOE GTP) | Open Energy...
Ground Gravity Survey At Glass Buttes Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Glass Buttes Area...
F.O.B. Costs of Imported Crude Oil by API Gravity
U.S. Energy Information Administration (EIA) Indexed Site
API Gravity (Dollars per Barrel) Period: Monthly Annual Download Series History Download Series History Definitions, Sources & Notes Definitions, Sources & Notes API Gravity Jul-15 ...
Kerns, J.A.; Stone, R.R.; Fabyan, J.
1985-02-12
A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.
Matsui, Hiroshi; Matsunaga, Tadashi
2010-11-16
A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.
Mixing lengths scaling in a gravity flow
Ecke, Robert E [Los Alamos National Laboratory; Rivera, Micheal [Los Alamos National Laboratory; Chen, Jun [Los Alamos National Laboratory; Ecke, Robert E [Los Alamos National Laboratory
2009-01-01
We present an experimental study of the mixing processes in a gravity current. The turbulent transport of momentum and buoyancy can be described in a very direct and compact form by a Prandtl mixing length model [1]: the turbulent vertical fluxes of momentum and buoyancy are found to scale quadraticatly with the vertical mean gradients of velocity and density. The scaling coefficient is the square of the mixing length, approximately constant over the mixing zone of the stratified shear layer. We show in this paper how, in different flow configurations, this length can be related to the shear length of the flow {radical}({var_epsilon}/{partial_derivative}{sub z}u{sup 3}).
Fryberger, D.
1984-12-01
In this talk on magnetic monopoles, first the author briefly reviews some historical background; then, the author describes what several different types of monopoles might look like; and finally the author discusses the experimental situation. 81 references.
Perihelion precession for modified Newtonian gravity
Schmidt, Hans-Juergen
2008-07-15
We calculate the perihelion precession {delta} for nearly circular orbits in a central potential V(r). Differently from other approaches to this problem, we do not assume that the potential is close to the Newtonian one. The main idea in the deduction is to apply the underlying symmetries of the system to show that {delta} must be a function of r{center_dot}V{sup ''}(r)/V{sup '}(r) and to use the transformation behavior of {delta} in a rotating system of reference. This is equivalent to say that the effective potential can be written in a one-parameter set of possibilities as the sum of centrifugal potential and potential of the central force. We get the following universal formula valid for V{sup '}(r)>0 reading {delta}(r)=2{pi}{center_dot}[(1/{radical}(3+r{center_dot}V{sup ''}(r)/V{sup '}(r)))-1]. It has to be read as follows: a circular orbit at this value r exists and is stable if and only if this {delta} is well-defined as real; and if this is the case, then the angular difference from one perihelion to the next one for nearly circular orbits at this r is exactly 2{pi}+{delta}(r). Then we apply this result to examples of recent interest like modified Newtonian gravity and linearized fourth-order gravity. In the second part of the paper, we generalize this universal formula to static spherically symmetric space-times ds{sup 2}=-e{sup 2{lambda}}{sup (r)}dt{sup 2}+e{sup 2{mu}}{sup (r)}dr{sup 2}+r{sup 2}d{omega}{sup 2}; for orbits near r it reads {delta}=2{pi}{center_dot}[(e{sup {mu}}{sup (r)}/{radical}(3-2r{center_dot}{lambda}{sup '}(r)+r{center_dot}{lambda}{sup ''}(r)/{lambda}{sup '}(r)))-1] and can be applied to a large class of theories. For the Schwarzschild black hole with mass parameter m>0 it leads to {delta}=2{pi}{center_dot}[(1/{radical}(1-(6m/r)))-1], a surprisingly unknown formula. It represents a strict result and is applicable for all values r>6m and is in good agreement with the fact that stable circular orbits exist for r>6m only. For r>>m, one can develop in powers of m and get the well-known approximation {delta}{approx_equal}(6{pi}m/r)
Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms
Lay, Erin H.; Shao, Xuan -Min; Kendrick, Alexander K.; Carrano, Charles S.
2015-07-30
Acoustic waves with periods of 2–4 min and gravity waves with periods of 6–16 min have been detected at ionospheric heights (25–350 km) using GPS total electron content measurements. The area disturbed by these waves and the wave amplitudes have been associated with underlying thunderstorm activity. A statistical study comparing Next Generation Weather Radar thunderstorm measurements with ionospheric acoustic and gravity waves in the midlatitude U.S. Great Plains region was performed for the time period of May–July 2005. An increase of ionospheric acoustic wave disturbed area and amplitude is primarily associated with large thunderstorms (mesoscale convective systems). Ionospheric gravity wave disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.
Ground Gravity Survey At Dixie Valley Geothermal Area (Iovenitti...
project area. These data were used in conjunction with past gravity data reported in by Smith et al (2001) and Blackwell et al (2005). The analysis of these data had not been...
Ground Gravity Survey At Truckhaven Area (Layman Energy Associates...
9. The 95 magnetotelluric (MT) soundings cover a central area of about 80 square kilometers. The 126 gravity stations extend over a broader area of about 150 square kilometers,...
Ground Gravity Survey At Mt Princeton Hot Springs Geothermal...
lithologic distrubtions Notes Gravity low associated with Mt. Princeton Batholith; density contrast of -0.5 gcm3 of valley-fill sediments relative to batholith References J.E....
Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Lay, Erin H.; Shao, Xuan -Min; Kendrick, Alexander K.; Carrano, Charles S.
2015-07-30
Acoustic waves with periods of 2â€“4 min and gravity waves with periods of 6â€“16 min have been detected at ionospheric heights (25â€“350 km) using GPS total electron content measurements. The area disturbed by these waves and the wave amplitudes have been associated with underlying thunderstorm activity. A statistical study comparing Next Generation Weather Radar thunderstorm measurements with ionospheric acoustic and gravity waves in the midlatitude U.S. Great Plains region was performed for the time period of Mayâ€“July 2005. An increase of ionospheric acoustic wave disturbed area and amplitude is primarily associated with large thunderstorms (mesoscale convective systems). Ionospheric gravity wavemoreÂ Â» disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.Â«Â less
Ground Gravity Survey At Dixie Valley Geothermal Area (Blackwell...
local studies conducted in the past. Gravity data measured in the 1970's by Hunt Oil, Sun Oil, and Southland royalty (all unpublished reports) ware used. These data were combined...
Ground Gravity Survey At Cove Fort Area - Vapor (Warpinski, Et...
Ground Gravity Survey Activity Date Usefulness not indicated DOE-funding Unknown Notes Update to Warpinski, et al., 2002 References N. R. Warpinski, A. R. Sattler, R. Fortuna, D....
Regional Gravity Survey of the Northern Great Salt Lake Desert...
of about -196 mgal over the alluvium-covered graben areas. The gravity high over the Raft River Mountains apparently corresponds with the Raft River Mountains anticline. A belt...
Dynamically stable magnetic suspension/bearing system
Post, R.F.
1996-02-27
A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements. 32 figs.
Dynamically stable magnetic suspension/bearing system
Post, Richard F. (Walnut Creek, CA)
1996-01-01
A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw's Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements.
Correlations estimate volume distilled using gravity, boiling point
Moreno, A.; Consuelo Perez de Alba, M. del; Manriquez, L.; Guardia Mendoz, P. de la
1995-10-23
Mathematical nd graphic correlations have been developed for estimating cumulative volume distilled as a function of crude API gravity and true boiling point (TBP). The correlations can be used for crudes with gravities of 21--34{degree} API and boiling points of 150--540 C. In distillation predictions for several mexican and Iraqi crude oils, the correlations have exhibited accuracy comparable to that of laboratory measurements. The paper discusses the need for such a correlation and the testing of the correlation.
Cosmological stability bound in massive gravity and bigravity
Fasiello, Matteo; Tolley, Andrew J. E-mail: andrew.j.tolley@case.edu
2013-12-01
We give a simple derivation of a cosmological bound on the graviton mass for spatially flat FRW solutions in massive gravity with an FRW reference metric and for bigravity theories. This bound comes from the requirement that the kinetic term of the helicity zero mode of the graviton is positive definite. The bound is dependent only on the parameters in the massive gravity potential and the Hubble expansion rate for the two metrics. We derive the decoupling limit of bigravity and FRW massive gravity, and use this to give an independent derivation of the cosmological bound. We recover our previous results that the tension between satisfying the Friedmann equation and the cosmological bound is sufficient to rule out all observationally relevant FRW solutions for massive gravity with an FRW reference metric. In contrast, in bigravity this tension is resolved due to different nature of the Vainshtein mechanism. We find that in bigravity theories there exists an FRW solution with late-time self-acceleration for which the kinetic terms for the helicity-2, helicity-1 and helicity-0 are generically nonzero and positive making this a compelling candidate for a model of cosmic acceleration. We confirm that the generalized bound is saturated for the candidate partially massless (bi)gravity theories but the existence of helicity-1/helicity-0 interactions implies the absence of the conjectured partially massless symmetry for both massive gravity and bigravity.
Finite field-dependent symmetries in perturbative quantum gravity
Upadhyay, Sudhaker
2014-01-15
In this paper we discuss the absolutely anticommuting nilpotent symmetries for perturbative quantum gravity in general curved spacetime in linear and non-linear gauges. Further, we analyze the finite field-dependent BRST (FFBRST) transformation for perturbative quantum gravity in general curved spacetime. The FFBRST transformation changes the gauge-fixing and ghost parts of the perturbative quantum gravity within functional integration. However, the operation of such symmetry transformation on the generating functional of perturbative quantum gravity does not affect the theory on physical ground. The FFBRST transformation with appropriate choices of finite BRST parameter connects non-linear Curci–Ferrari and Landau gauges of perturbative quantum gravity. The validity of the results is also established at quantum level using Batalin–Vilkovisky (BV) formulation. -- Highlights: •The perturbative quantum gravity is treated as gauge theory. •BRST and anti-BRST transformations are developed in linear and non-linear gauges. •BRST transformation is generalized by making it finite and field dependent. •Connection between linear and non-linear gauges is established. •Using BV formulation the results are established at quantum level also.
TESTING ALTERNATIVE THEORIES OF GRAVITY USING THE SUN
Casanellas, Jordi; Pani, Paolo; Lopes, Ilidio; Cardoso, Vitor E-mail: paolo.pani@ist.utl.pt E-mail: vitor.cardoso@ist.utl.pt
2012-01-20
We propose a new approach to test possible corrections to Newtonian gravity using solar physics. The high accuracy of current solar models and new precise observations allow us to constrain corrections to standard gravity at unprecedented levels. Our case study is Eddington-inspired gravity, an attractive modified theory of gravity which results in non-singular cosmology and collapse. The theory is equivalent to standard gravity in vacuum, but it sensibly differs from it within matter. For instance, it affects the evolution and the equilibrium structure of the Sun, giving different core temperature profiles, and deviations in the observed acoustic modes and in solar neutrino fluxes. Comparing the predictions from a modified solar model with observations, we constrain the coupling parameter of the theory, |{kappa}{sub g}| {approx}< 3 Multiplication-Sign 10{sup 5} m{sup 5} s{sup -2} kg{sup -1}. Our results show that the Sun can be used to efficiently constrain alternative theories of gravity.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
... Underlying the magnetocaloric effect is the idea that magnetism is the result of the ... with the magnetic field, the magnetic entropy (disorder) of the system decreases; if ...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
enhanced magnetic refrigeration at very low temperatures. Not Your Mother's Refrigerator Magnets Some day soon, magnets could do more than clutter up the front of your...
Aeromagnetic and gravity surveys in the Coso Range, California...
some magnetite in the more magnetic wall rock, further reducing the magnetic intensity. Authors Plouff, D.; Isherwood and W.F. Published Journal Journal of Geophysical...
First tsunami gravity wave detection in ionospheric radio occultation data
Coïsson, Pierdavide; Lognonné, Philippe; Walwer, Damian; Rolland, Lucie M.
2015-05-09
After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing the vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.
Correlation between precision gravity and subsidence measurements at Cerro Prieto
Zelwer, R.; Grannell, R.B.
1982-10-01
Precision gravity measurements were made in the region of the Cerro Prieto geothermal field at yearly intervals from 1977 to 1981 to assess the feasibility of using gravity to determine subsurface reservoir changes with time. The extent of mass recharge in response to the continued production of fluids from this field was studied. Changes in gravity and ground elevation were observed throughout the region for the period of observation. Results indicate that the largest changes observed were the result of the Magnitude 6.1 (Caltech) Victoria earthquake of 8 June 1980. The epicenter of this earthquake was located 25 km southeast of the field on the Cerro Prieto Fault, which bounds the field on the southwest. Subsidence of up to 55 cm was measured east of the power plant, in the region between the northern end of the Cerro Prieto Fault and the southern end of the Imperial Fault. This area has been postulated to be the site of an active spreading center or pull-apart basin, and has been characterized by a high level of seismic activity during the last 10 years. Minor subsidence and small related gravity changes for the period preceeding the Victoria earthquake suggest that in spite of large fluid production rates, the reservoir is being almost completely recharged and that a measurable increase in subsurface density may be taking place. The results of measurements of horizontal ground motions made in this area are discussed in relation to the gravity and subsidence observations.
First tsunami gravity wave detection in ionospheric radio occultation data
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
CoÃ¯sson, Pierdavide; LognonnÃ©, Philippe; Walwer, Damian; Rolland, Lucie M.
2015-05-09
After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing themoreÂ Â» vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.Â«Â less
On the null trajectories in conformal Weyl gravity
Villanueva, J.R.; Olivares, Marco E-mail: marco.olivaresrubilar@gmail.com
2013-06-01
In this work we find analytical solutions to the null geodesics around a black hole in the conformal Weyl gravity. Exact expressions for the horizons are found, and they depend on the cosmological constant and the coupling constants of the conformal Weyl gravity. Then, we study the radial motion from the point of view of the proper and coordinate frames, and compare it with that found in spacetimes of general relativity. The angular motion is also examined qualitatively by means of an effective potential; quantitatively, the equation of motion is solved in terms of wp-Weierstrass elliptic function. Thus, we find the deflection angle for photons without using any approximation, which is a novel result for this kind of gravity.
Monitoring the Bulalo geothermal reservoir, Philippines, using precision gravity data
San Andres, R.B.; Pedersen, J.R.
1993-10-01
Precision gravity monitoring of the Bulalo geothermal field began in 1980 to estimate the natural mass recharge to the reservoir. Between 1980 and 1991, gravity decreases exceeding 2.5 {times} 10{sup {minus}6} N/kg (250 microgals) were observed in response to fluid withdrawals. A maximum rate of {minus}26 microgals per year was observed near the production center. Mass discharges predicted by recent reservoir simulation modeling generally match those inferred from the observed gravity data. According to simulation studies, no recharge occurred between 1980 and 1984. The mass recharge between 1984 and 1991 was estimated to be 30% of net fluid withdrawal during the same period, equivalent to an average rate of 175 kg/s (630 metric tons per hour).
Masaaki Yamada, Russell Kulsrud and Hantao Ji
2009-09-17
We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two- uid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also brie y discussed.
Spectral regularisation: induced gravity and the onset of inflation
Kurkov, Max A.; Sakellariadou, Mairi E-mail: mairi.sakellariadou@kcl.ac.uk
2014-01-01
Using spectral regularisation, we compute the Weyl anomaly and express the anomaly generating functional of the quantum effective action through a collective scalar degree of freedom of all quantum vacuum fluctuations. Such a formulation allows us to describe induced gravity on an equal footing with the anomaly-induced effective action, in a self-consistent way. We then show that requiring stability of the cosmological constant under loop quantum corrections, Sakharov's induced gravity and Starobinsky's anomaly-induced inflation are either both present or both absent, depending on the particle content of the theory.
Minimum length, extra dimensions, modified gravity and black hole remnants
Maziashvili, Michael
2013-03-01
We construct a Hilbert space representation of minimum-length deformed uncertainty relation in presence of extra dimensions. Following this construction, we study corrections to the gravitational potential (back reaction on gravity) with the use of correspondingly modified propagator in presence of two (spatial) extra dimensions. Interestingly enough, for r?0 the gravitational force approaches zero and the horizon for modified Schwarzschild-Tangherlini space-time disappears when the mass approaches quantum-gravity energy scale. This result points out to the existence of zero-temperature black hole remnants in ADD brane-world model.
Stabilization of linear higher derivative gravity with constraints
Chen, Tai-jun; Lim, Eugene A. E-mail: eugene.a.lim@gmail.com
2014-05-01
We show that the instabilities of higher derivative gravity models with quadratic curvature invariant ?R{sup 2}+?R{sub ??}R{sup ??} can be removed by judicious addition of constraints at the quadratic level of metric fluctuations around Minkowski/de Sitter background. With a suitable parameter choice, we find that the instabilities of helicity-0, 1, 2 modes can be removed while reducing the dimensionality of the original phase space. To retain the renormalization properties of higher derivative gravity, Lorentz symmetry in the constrained theory is explicitly broken.
Spherically symmetric static spacetimes in vacuum f(T) gravity
Ferraro, Rafael; Fiorini, Franco
2011-10-15
We show that Schwarzschild geometry remains as a vacuum solution for those four-dimensional f(T) gravitational theories behaving as ultraviolet deformations of general relativity. In the gentler context of three-dimensional gravity, we also find that the infrared-deformed f(T) gravities, like the ones used to describe the late cosmic speed up of the Universe, have as the circularly symmetric vacuum solution a Deser-de Sitter or a Banados, Teitelboim and Zanelli-like spacetime with an effective cosmological constant depending on the infrared scale present in the function f(T).
Gravitomagnetic gyroscope precession in Palatini f(R) gravity
Ruggiero, Matteo Luca
2009-04-15
We study gravitomagnetic effects in the Palatini formalism of f(R) gravity. On using the Kerr-de Sitter metric, which is a solution of f(R) field equations, we calculate the impact of f(R) gravity on the gravitomagnetic precession of an orbiting gyroscope. We show that, even though an f(R) contribution is present in principle, its magnitude is negligibly small and far to be detectable in the present (like GP-B) and foreseeable space missions or observational tests around the Earth.
Gravity Survey of the Carson Sink - Data and Maps
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Faulds, James E.
Preliminary Interpretation of Results: The Carson Sink is a complex composite basin with several major depocenters (Figures 15 and 16). Major depocenters are present in the south?central, east?central, and northeastern parts of the basin. The distribution of gravity anomalies suggests a complex pattern of faulting in the subsurface of the basin, with many fault terminations, step?overs, and accommodation zones. The pattern of faulting implies that other, previously undiscovered blind geothermal systems are likely in the Carson Sink. The gravity survey was completed near the end of this project. Thus, more thorough analysis of the data and potential locations of blind geothermal systems is planned for future work.
Gravity Survey of the Carson Sink - Data and Maps
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Faulds, James E.
2013-12-31
Preliminary Interpretation of Results: The Carson Sink is a complex composite basin with several major depocenters (Figures 15 and 16). Major depocenters are present in the south?central, east?central, and northeastern parts of the basin. The distribution of gravity anomalies suggests a complex pattern of faulting in the subsurface of the basin, with many fault terminations, step?overs, and accommodation zones. The pattern of faulting implies that other, previously undiscovered blind geothermal systems are likely in the Carson Sink. The gravity survey was completed near the end of this project. Thus, more thorough analysis of the data and potential locations of blind geothermal systems is planned for future work.
Flat 3-brane with Tension in Cascading Gravity
Rham, Claudia de; Khoury, Justin; Tolley, Andrew
2009-10-16
In the cascading gravity brane-world scenario, our 3-brane lies within a succession of lower-codimension branes, each with their own induced gravity term, embedded into each other in a higher-dimensional space-time. In the (6+1)-dimensional version of this scenario, we show that a 3-brane with tension remains flat, at least for sufficiently small tension that the weak-field approximation is valid. The bulk solution is singular nowhere and remains in the perturbative regime everywhere.
On the gauge features of gravity on a Lie algebroid structure
Fabi, S. Harms, B. Hou, S.
2014-03-15
We present the geometric formulation of gravity based on the mathematical structure of a Lie Algebroid. We show that this framework provides the geometrical setting to describe the gauge propriety of gravity.
Problems with propagation and time evolution inf(T)gravity (Journal...
Office of Scientific and Technical Information (OSTI)
Problems with propagation and time evolution inf(T)gravity Citation Details In-Document Search Title: Problems with propagation and time evolution inf(T)gravity Authors: Ong, Yen...
Toward large N thermal QCD from dual gravity: The heavy quarkonium...
Office of Scientific and Technical Information (OSTI)
We continue our study on the gravity duals for strongly coupled large N QCD with fundamental flavors both at zero and nonzero temperatures. The gravity dual at zero temperature ...
GravitoMagnetic force in modified Newtonian dynamics
Exirifard, Qasem
2013-08-01
We introduce the Gauge Vector-Tensor (GVT) theory by extending the AQUAL's approach to the GravitoElectroMagnetism (GEM) approximation of gravity. GVT is a generally covariant theory of gravity composed of a pseudo Riemannian metric and two U(1) gauge connections that reproduces MOND in the limit of very weak gravitational fields while remains consistent with the Einstein-Hilbert gravity in the limit of strong and Newtonian gravitational fields. GVT also provides a simple framework to study the GEM approximation to gravity. We illustrate that the gravitomagnetic force at the edge of a galaxy can be in accord with either GVT or ?CDM but not both. We also study the physics of the GVT theory around the gravitational saddle point of the Sun and Jupiter system. We notice that the conclusive refusal of the GVT theory demands measuring either both of the gravitoelectric and gravitomagnetic fields inside the Sun-Jupiter MOND window, or the gravitoelectric field inside two different solar GVT MOND windows. The GVT theory, however, will be favored by observing an anomaly in the gravitoelectric field inside a single MOND window.
Toward large N thermal QCD from dual gravity: The heavy quarkonium
Office of Scientific and Technical Information (OSTI)
potential (Journal Article) | SciTech Connect Toward large N thermal QCD from dual gravity: The heavy quarkonium potential Citation Details In-Document Search Title: Toward large N thermal QCD from dual gravity: The heavy quarkonium potential We continue our study on the gravity duals for strongly coupled large N QCD with fundamental flavors both at zero and nonzero temperatures. The gravity dual at zero temperature captures the logarithmic runnings of the coupling constants at far IR and
Complete Bouguer gravity map of the Nevada Test Site and vicinity, Nevada
Healey, D.L.; Harris, R.N.; Ponce, D.A.; Oliver, H.W.
1987-12-31
About 15,000 gravity stations were used to create the gravity map. Gravity studies at the Nevada Test Site were undertaken to help locate geologically favorable areas for underground nuclear tests and to help characterize potential high-level nuclear waste storage sites. 48 refs. (TEM)
Entirely passive heat pipe apparatus capable of operating against gravity
Koenig, Daniel R. (Santa Fe, NM)
1982-01-01
The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 meters and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.
Further stable neutron star models from f(R) gravity
Astashenok, Artyom V.; Capozziello, Salvatore; Odintsov, Sergei D. E-mail: capozziello@na.infn.it
2013-12-01
Neutron star models in perturbative f(R) gravity are considered with realistic equations of state. In particular, we consider the FPS, SLy and other equations of state and a case of piecewise equation of state for stars with quark cores. The mass-radius relations for f(R) = R+R(e{sup ?R/R{sub 0}}?1) model and for R{sup 2} models with logarithmic and cubic corrections are obtained. In the case of R{sup 2} gravity with cubic corrections, we obtain that at high central densities (? > 10?{sub ns}, where ?{sub ns} = 2.7 × 10{sup 14} g/cm{sup 3} is the nuclear saturation density), stable star configurations exist. The minimal radius of such stars is close to 9 km with maximal mass ? 1.9M{sub ?} (SLy equation). A similar situation takes place for AP4 and BSK20 EoS. Such an effect can give rise to more compact stars than in General Relativity. If observationally identified, such objects could constitute a formidable signature for modified gravity at astrophysical level. Another interesting result can be achieved in modified gravity with only a cubic correction. For some EoS, the upper limit of neutron star mass increases and therefore these EoS can describe realistic star configurations (although, in General Relativity, these EoS are excluded by observational constraints)
On singularities of capillary surfaces in the absence of gravity
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Roytburd, V.
1983-01-01
We study numerical solutions to the equation of capillary surfaces in trapezoidal domains in the absence of gravity when the boundary contact angle declines from 90 ° to some critical value. We also discuss a result on the behavior of solutions in more general domains that confirms numerical calculations.
Cartan gravity, matter fields, and the gauge principle
Westman, Hans F.; Zlosnik, Tom G.
2013-07-15
Gravity is commonly thought of as one of the four force fields in nature. However, in standard formulations its mathematical structure is rather different from the Yang–Mills fields of particle physics that govern the electromagnetic, weak, and strong interactions. This paper explores this dissonance with particular focus on how gravity couples to matter from the perspective of the Cartan-geometric formulation of gravity. There the gravitational field is represented by a pair of variables: (1) a ‘contact vector’ V{sup A} which is geometrically visualized as the contact point between the spacetime manifold and a model spacetime being ‘rolled’ on top of it, and (2) a gauge connection A{sub ?}{sup AB}, here taken to be valued in the Lie algebra of SO(2,3) or SO(1,4), which mathematically determines how much the model spacetime is rotated when rolled. By insisting on two principles, the gauge principle and polynomial simplicity, we shall show how one can reformulate matter field actions in a way that is harmonious with Cartan’s geometric construction. This yields a formulation of all matter fields in terms of first order partial differential equations. We show in detail how the standard second order formulation can be recovered. In particular, the Hodge dual, which characterizes the structure of bosonic field equations, pops up automatically. Furthermore, the energy–momentum and spin-density three-forms are naturally combined into a single object here denoted the spin-energy–momentum three-form. Finally, we highlight a peculiarity in the mathematical structure of our first-order formulation of Yang–Mills fields. This suggests a way to unify a U(1) gauge field with gravity into a SO(1,5)-valued gauge field using a natural generalization of Cartan geometry in which the larger symmetry group is spontaneously broken down to SO(1,3)×U(1). The coupling of this unified theory to matter fields and possible extensions to non-Abelian gauge fields are left as open questions. -- Highlights: •Develops Cartan gravity to include matter fields. •Coupling to gravity is done using the standard gauge prescription. •Matter actions are manifestly polynomial in all field variables. •Standard equations recovered on-shell for scalar, spinor and Yang–Mills fields. •Unification of a U(1) field with gravity based on the orthogonal group SO(1,5)
Gravity monitoring of CO2 movement during sequestration: Model studies
Gasperikova, E.; Hoversten, G.M.
2008-07-15
We examine the relative merits of gravity measurements as a monitoring tool for geological CO{sub 2} sequestration in three different modeling scenarios. The first is a combined CO{sub 2} enhanced oil recovery (EOR) and sequestration in a producing oil field, the second is sequestration in a brine formation, and the third is for a coalbed methane formation. EOR/sequestration petroleum reservoirs have relatively thin injection intervals with multiple fluid components (oil, hydrocarbon gas, brine, and CO{sub 2}), whereas brine formations usually have much thicker injection intervals and only two components (brine and CO{sub 2}). Coal formations undergoing methane extraction tend to be thin (3-10 m), but shallow compared to either EOR or brine formations. The injection of CO{sub 2} into the oil reservoir produced a bulk density decrease in the reservoir. The spatial pattern of the change in the vertical component of gravity (G{sub z}) is directly correlated with the net change in reservoir density. Furthermore, time-lapse changes in the borehole G{sub z} clearly identified the vertical section of the reservoir where fluid saturations are changing. The CO{sub 2}-brine front, on the order of 1 km within a 20 m thick brine formation at 1900 m depth, with 30% CO{sub 2} and 70% brine saturations, respectively, produced a -10 Gal surface gravity anomaly. Such anomaly would be detectable in the field. The amount of CO{sub 2} in a coalbed methane test scenario did not produce a large enough surface gravity response; however, we would expect that for an industrial size injection, the surface gravity response would be measurable. Gravity inversions in all three scenarios illustrated that the general position of density changes caused by CO{sub 2} can be recovered, but not the absolute value of the change. Analysis of the spatial resolution and detectability limits shows that gravity measurements could, under certain circumstances, be used as a lower-cost alternative to seismic measurements.
Satti, John A. (Naperville, IL)
1980-01-01
A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.
Multi-gravity separator: an alternate gravity concentrator to process coal fines
Majumder, A.K.; Bhoi, K.S.; Barnwal, J.P.
2007-08-15
The multi-gravity separator (MGS) is a novel piece of equipment for the separation of fine and ultra-fine minerals. However, the published literature does not demonstrate its use in the separation of coal fines. Therefore, an attempt was made to study the effects of different process variables on the performance of an MGS for the beneficiation of coal fines. The results obtained from this study revealed that among the parameters studied, drum rotation and feed solids concentration play dominating roles in controlling the yield and ash content of the clean coal. Mathematical modeling equations that correlate the variables studied and the yield and ash contents of the clean coal were developed to predict the performance of an MGS under different operating and design conditions. The entire exercise revealed that the MGS could produce a clean coal with an ash content of 14.67% and a yield of 71.23% from a feed coal having an ash content of 24.61 %.
Matt, Sean P.; Pinsonneault, Marc H.; Greene, Thomas P. E-mail: kmac@ucar.edu E-mail: thomas.p.greene@nasa.gov
2012-08-01
We use two-dimensional axisymmetric magnetohydrodynamic simulations to compute steady-state solutions for solar-like stellar winds from rotating stars with dipolar magnetic fields. Our parameter study includes 50 simulations covering a wide range of relative magnetic field strengths and rotation rates, extending from the slow- and approaching the fast-magnetic-rotator regimes. Using the simulations to compute the angular momentum loss, we derive a semi-analytic formulation for the external torque on the star that fits all of the simulations to a precision of a few percent. This formula provides a simple method for computing the magnetic braking of Sun-like stars due to magnetized stellar winds, which properly includes the dependence on the strength of the magnetic field, mass loss rate, stellar radius, surface gravity, and spin rate, and which is valid for both slow and fast rotators.
Approach to Fast Liquid Metal Flow Up a Magnetic Field Gradient | Princeton
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Plasma Physics Lab Approach to Fast Liquid Metal Flow Up a Magnetic Field Gradient Electrical and magnetic field (J x B) forces can be used to support flowing liquid metal against gravity. In a tokamak, the radial magnetic field gradient implies that JxB decreases inversely as the major radius, for constant current density in the liquid metal. This field gradient produces a pressure gradient along the support wall, which pushes the liquid metal towards the low field side. The invention
CONDITIONS FOR TRANSVERSE WAVES PROPAGATION ALONG THIN MAGNETIC FLUX TUBES ON THE SUN
Lopin, Igor; Nagorny, Ivan
2013-09-10
The propagation of kink waves in the thin gravity stratified flux tubes with a generalized magnetic field distribution model is considered in cylindrical geometry. The new kink wave equations for both wave variables are obtained. It is shown that the inclusion of the radial component of an unperturbed tube magnetic field sufficiently transforms the conditions for the propagation of transverse waves. It is demonstrated that, for the models of isothermal and polytropic atmosphere in the tube and its environment, the propagation of kink waves along thin magnetic flux tubes is cutoff-free.
Chell, Jeremy; Zimm, Carl B.
2006-12-12
A permanent magnet assembly is disclosed that is adapted to provide a magnetic field across an arc-shaped gap. Such a permanent magnet assembly can be used, for example, to provide a time-varying magnetic field to an annular region for use in a magnetic refrigerator.
Infrared lessons for ultraviolet gravity: the case of massive gravity and Born-Infeld
Jiménez, Jose Beltrán; Heisenberg, Lavinia; Olmo, Gonzalo J. E-mail: Lavinia.Heisenberg@unige.ch
2014-11-01
We generalize the ultraviolet sector of gravitation via a Born-Infeld action using lessons from massive gravity. The theory contains all of the elementary symmetric polynomials and is treated in the Palatini formalism. We show how the connection can be solved algebraically to be the Levi-Civita connection of an effective metric. The non-linearity of the algebraic equations yields several branches, one of which always reduces to General Relativity at low curvatures. We explore in detail a minimal version of the theory, for which we study solutions in the presence of a perfect fluid with special attention to the cosmological evolution. In vacuum we recover Ricci-flat solutions, but also an additional physical solution corresponding to an Einstein space. The existence of two physical branches remains for non-vacuum solutions and, in addition, the branch that connects to the Einstein space in vacuum is not very sensitive to the specific value of the energy density. For the branch that connects to the General Relativity limit we generically find three behaviours for the Hubble function depending on the equation of state of the fluid, namely: either there is a maximum value for the energy density that connects continuously with vacuum, or the energy density can be arbitrarily large but the Hubble function saturates and remains constant at high energy densities, or the energy density is unbounded and the Hubble function grows faster than in General Relativity. The second case is particularly interesting because it could offer an interesting inflationary epoch even in the presence of a dust component. Finally, we discuss the possibility of avoiding certain types of singularities within the minimal model.
Translation invariant time-dependent solutions to massive gravity
Mourad, J.; Steer, D.A. E-mail: steer@apc.univ-paris7.fr
2013-12-01
Homogeneous time-dependent solutions of massive gravity generalise the plane wave solutions of the linearised Fierz-Pauli equations for a massive spin-two particle, as well as the Kasner solutions of General Relativity. We show that they also allow a clear counting of the degrees of freedom and represent a simplified framework to work out the constraints, the equations of motion and the initial value formulation. We work in the vielbein formulation of massive gravity, find the phase space resulting from the constraints and show that several disconnected sectors of solutions exist some of which are unstable. The initial values determine the sector to which a solution belongs. Classically, the theory is not pathological but quantum mechanically the theory may suffer from instabilities. The latter are not due to an extra ghost-like degree of freedom.
Trapping and aerogelation of nanoparticles in negative gravity hydrocarbon flames
Chakrabarty, Rajan K.; Novosselov, Igor V.; Beres, Nicholas D.; Moosmüller, Hans; Sorensen, Christopher M.; Stipe, Christopher B.
2014-06-16
We report the experimental realization of continuous carbon aerogel production using a flame aerosol reactor by operating it in negative gravity (?g; up-side-down configuration). Buoyancy opposes the fuel and air flow forces in ?g, which eliminates convectional outflow of nanoparticles from the flame and traps them in a distinctive non-tipping, flicker-free, cylindrical flame body, where they grow to millimeter-size aerogel particles and gravitationally fall out. Computational fluid dynamics simulations show that a closed-loop recirculation zone is set up in ?g flames, which reduces the time to gel for nanoparticles by ?10{sup 6}?s, compared to positive gravity (upward rising) flames. Our results open up new possibilities of one-step gas-phase synthesis of a wide variety of aerogels on an industrial scale.
Cosmological perturbations in non-local higher-derivative gravity
Craps, Ben; Jonckheere, Tim De; Koshelev, Alexey S. E-mail: Tim.De.Jonckheere@vub.ac.be
2014-11-01
We study cosmological perturbations in a non-local higher-derivative model of gravity introduced by Biswas, Mazumdar and Siegel. We extend previous work, which had focused on classical scalar perturbations around a cosine hyperbolic bounce solution, in three ways. First, we point out the existence of a Starobinsky solution in this model, which is more attractive from a phenomenological point of view (even though it has no bounce). Second, we study classical vector and tensor pertuxsxrbations. Third, we show how to quantize scalar and tensor perturbations in a de Sitter phase (for choices of parameters such that the model is ghost-free). Our results show that the model is well-behaved at this level, and are very similar to corresponding results in local f(R) models. In particular, for the Starobinsky solution of non-local higher-derivative gravity, we find the same tensor-to-scalar ratio as for the conventional Starobinsky model.
Constraints on axion inflation from the weak gravity conjecture
Rudelius, Tom
2015-09-08
We derive constraints facing models of axion inflation based on decay constant alignment from a string-theoretic and quantum gravitational perspective. In particular, we investigate the prospects for alignment and â€˜anti-alignmentâ€™ of C{sub 4} axion decay constants in type IIB string theory, deriving a strict no-go result in the latter case. We discuss the relationship of axion decay constants to the weak gravity conjecture and demonstrate agreement between our string-theoretic constraints and those coming from the â€˜generalizedâ€™ weak gravity conjecture. Finally, we consider a particular model of decay constant alignment in which the potential of C{sub 4} axions in type IIB compactifications on a Calabi-Yau three-fold is dominated by contributions from D7-branes, pointing out that this model evades some of the challenges derived earlier in our paper but is highly constrained by other geometric considerations.
Structure formation in a nonlocally modified gravity model
Park, Sohyun; Dodelson, Scott
2013-01-01
We study a nonlocally modified gravity model proposed by Deser and Woodard which gives an explanation for current cosmic acceleration. By deriving and solving the equations governing the evolution of the structure in the Universe, we show that this model predicts a pattern of growth that differs from standard general relativity (+dark energy) at the 10-30% level. These differences will be easily probed by the next generation of galaxy surveys, so the model should be tested shortly.
Quantum Gravity corrections and entropy at the Planck time
Basilakos, Spyros; Vagenas, Elias C.; Das, Saurya E-mail: saurya.das@uleth.ca
2010-09-01
We investigate the effects of Quantum Gravity on the Planck era of the universe. In particular, using different versions of the Generalized Uncertainty Principle and under specific conditions we find that the main Planck quantities such as the Planck time, length, mass and energy become larger by a factor of order 10?10{sup 4} compared to those quantities which result from the Heisenberg Uncertainty Principle. However, we prove that the dimensionless entropy enclosed in the cosmological horizon at the Planck time remains unchanged. These results, though preliminary, indicate that we should anticipate modifications in the set-up of cosmology since changes in the Planck era will be inherited even to the late universe through the framework of Quantum Gravity (or Quantum Field Theory) which utilizes the Planck scale as a fundamental one. More importantly, these corrections will not affect the entropic content of the universe at the Planck time which is a crucial element for one of the basic principles of Quantum Gravity named Holographic Principle.
The observational status of Galileon gravity after Planck
Barreira, Alexandre; Li, Baojiu; Baugh, Carlton M.; Pascoli, Silvia E-mail: baojiu.li@durham.ac.uk E-mail: silvia.pascoli@durham.ac.uk
2014-08-01
We use the latest CMB data from Planck, together with BAO measurements, to constrain the full parameter space of Galileon gravity. We constrain separately the three main branches of the theory known as the Cubic, Quartic and Quintic models, and find that all yield a very good fit to these data. Unlike in ?CDM, the Galileon model constraints are compatible with local determinations of the Hubble parameter and predict nonzero neutrino masses at over 5? significance. We also identify that the low l part of the CMB lensing spectrum may be able to distinguish between ?CDM and Galileon models. In the Cubic model, the lensing potential deepens at late times on sub-horizon scales, which is at odds with the current observational suggestion of a positive ISW effect. Compared to ?CDM, the Quartic and Quintic models predict less ISW power in the low l region of the CMB temperature spectrum, and as such are slightly preferred by the Planck data. We illustrate that residual local modifications to gravity in the Quartic and Quintic models may render the Cubic model as the only branch of Galileon gravity that passes Solar System tests.
Cosmological perturbation in f(T) gravity revisited
Izumi, Keisuke; Ong, Yen Chin E-mail: ongyenchin@member.ams.org
2013-06-01
We perform detailed investigation of cosmological perturbations in f(T) theory of gravity coupled with scalar field. Our work emphasizes on the way to gauge fix the theory and we examine all possible modes of perturbations up to second order. The analysis includes pseudoscalar and pseudovector modes in addition to the usual scalar, vector, and tensor modes. We find no gravitational propagating degree of freedom in the scalar, pseudoscalar, vector, as well as pseudovector modes. In addition, we find that the scalar and tensor perturbations have exactly the same form as their counterparts in usual general relativity with scalar field, except that the factor of reduced Planck mass squared M{sub pl}{sup 2}?1/(8?G) that occurs in the latter has now been replaced by an effective time-dependent gravitational coupling ?2(df/dT)|{sub T=T{sub 0}}, with T{sub 0} being the background torsion scalar. The absence of extra degrees of freedom of f(T) gravity at second order linear perturbation indicates that f(T) gravity is highly nonlinear. Consequently one cannot conclusively analyze stability of the theory without performing nonlinear analysis that can reveal the propagation of the extra degrees of freedom.
Disformal theories of gravity: from the solar system to cosmology
Sakstein, Jeremy
2014-12-01
This paper is concerned with theories of gravity that contain a scalar coupled both conformally and disformally to matter through the metric. By systematically deriving the non-relativistic limit, it is shown that no new non-linear screening mechanisms are present beyond the Vainshtein mechanism and chameleon-like screening. If one includes the cosmological expansion of the universe, disformal effects that are usually taken to be absent can be present in the solar system. When the conformal factor is absent, fifth-forces can be screened on all scales when the cosmological field is slowly-rolling. We investigate the cosmology of these models and use local tests of gravity to place new constraints on the disformal coupling and find M ?> O(eV), which is not competitive with laboratory tests. Finally, we discuss the future prospects for testing these theories and the implications for other theories of modified gravity. In particular, the Vainshtein radius of solar system objects can be altered from the static prediction when cosmological time-derivatives are non-negligible.
WILSON-BAPPU EFFECT: EXTENDED TO SURFACE GRAVITY
Park, Sunkyung; Kang, Wonseok; Lee, Jeong-Eun; Lee, Sang-Gak E-mail: wskang@khu.ac.kr E-mail: sanggak@snu.ac.kr
2013-10-01
In 1957, Wilson and Bappu found a tight correlation between the stellar absolute visual magnitude (M{sub V} ) and the width of the Ca II K emission line for late-type stars. Here, we revisit the Wilson-Bappu relationship (WBR) to claim that the WBR can be an excellent indicator of stellar surface gravity of late-type stars as well as a distance indicator. We have measured the width (W) of the Ca II K emission line in high-resolution spectra of 125 late-type stars obtained with the Bohyunsan Optical Echelle Spectrograph and adopted from the Ultraviolet and Visual Echelle Spectrograph archive. Based on our measurement of the emission line width (W), we have obtained a WBR of M{sub V} = 33.76 - 18.08 log W. In order to extend the WBR to being a surface gravity indicator, stellar atmospheric parameters such as effective temperature (T{sub eff}), surface gravity (log g), metallicity ([Fe/H]), and micro-turbulence ({xi}{sub tur}) have been derived from self-consistent detailed analysis using the Kurucz stellar atmospheric model and the abundance analysis code, MOOG. Using these stellar parameters and log W, we found that log g = -5.85 log W+9.97 log T{sub eff} - 23.48 for late-type stars.
Nonlinear structure formation in the cubic Galileon gravity model
Barreira, Alexandre; Li, Baojiu; Hellwing, Wojciech A.; Baugh, Carlton M.; Pascoli, Silvia E-mail: baojiu.li@durham.ac.uk E-mail: c.m.baugh@durham.ac.uk
2013-10-01
We model the linear and nonlinear growth of large scale structure in the Cubic Galileon gravity model, by running a suite of N-body cosmological simulations using the ECOSMOG code. Our simulations include the Vainshtein screening effect, which reconciles the Cubic Galileon model with local tests of gravity. In the linear regime, the amplitude of the matter power spectrum increases by ? 20% with respect to the standard ?CDM model today. The modified expansion rate accounts for ? 15% of this enhancement, while the fifth force is responsible for only ? 5%. This is because the effective unscreened gravitational strength deviates from standard gravity only at late times, even though it can be twice as large today. In the nonlinear regime (k?>0.1h Mpc{sup ?1}), the fifth force leads to only a modest increase (?<8%) in the clustering power on all scales due to the very efficient operation of the Vainshtein mechanism. Such a strong effect is typically not seen in other models with the same screening mechanism. The screening also results in the fifth force increasing the number density of halos by less than 10%, on all mass scales. Our results show that the screening does not ruin the validity of linear theory on large scales which anticipates very strong constraints from galaxy clustering data. We also show that, whilst the model gives an excellent match to CMB data on small angular scales (l?>50), the predicted integrated Sachs-Wolfe effect is in tension with Planck/WMAP results.
Affine group formulation of the Standard Model coupled to gravity
Chou, Ching-Yi; Ita, Eyo; Soo, Chopin
2014-04-15
In this work we apply the affine group formalism for four dimensional gravity of Lorentzian signature, which is based on Klauder’s affine algebraic program, to the formulation of the Hamiltonian constraint of the interaction of matter and all forces, including gravity with non-vanishing cosmological constant ?, as an affine Lie algebra. We use the hermitian action of fermions coupled to gravitation and Yang–Mills theory to find the density weight one fermionic super-Hamiltonian constraint. This term, combined with the Yang–Mills and Higgs energy densities, are composed with York’s integrated time functional. The result, when combined with the imaginary part of the Chern–Simons functional Q, forms the affine commutation relation with the volume element V(x). Affine algebraic quantization of gravitation and matter on equal footing implies a fundamental uncertainty relation which is predicated upon a non-vanishing cosmological constant. -- Highlights: •Wheeler–DeWitt equation (WDW) quantized as affine algebra, realizing Klauder’s program. •WDW formulated for interaction of matter and all forces, including gravity, as affine algebra. •WDW features Hermitian generators in spite of fermionic content: Standard Model addressed. •Constructed a family of physical states for the full, coupled theory via affine coherent states. •Fundamental uncertainty relation, predicated on non-vanishing cosmological constant.
Halo model and halo properties in Galileon gravity cosmologies
Barreira, Alexandre; Li, Baojiu; Hellwing, Wojciech A.; Baugh, Carlton M.; Lombriser, Lucas; Pascoli, Silvia E-mail: baojiu.li@durham.ac.uk E-mail: llo@roe.ac.uk E-mail: silvia.pascoli@durham.ac.uk
2014-04-01
We investigate the performance of semi-analytical modelling of large-scale structure in Galileon gravity cosmologies using results from N-body simulations. We focus on the Cubic and Quartic Galileon models that provide a reasonable fit to CMB, SNIa and BAO data. We demonstrate that the Sheth-Tormen mass function and linear halo bias can be calibrated to provide a very good fit to our simulation results. We also find that the halo concentration-mass relation is well fitted by a power law. The nonlinear matter power spectrum computed in the halo model approach is found to be inaccurate in the mildly nonlinear regime, but captures reasonably well the effects of the Vainshtein screening mechanism on small scales. In the Cubic model, the screening mechanism hides essentially all of the effects of the fifth force inside haloes. In the case of the Quartic model, the screening mechanism leaves behind residual modifications to gravity, which make the effective gravitational strength time-varying and smaller than the standard value. Compared to normal gravity, this causes a deficiency of massive haloes and leads to a weaker matter clustering on small scales. For both models, we show that there are realistic halo occupation distributions of Luminous Red Galaxies that can match both the observed large-scale clustering amplitude and the number density of these galaxies.
The role of vector fields in modified gravity scenarios
Tasinato, Gianmassimo; Koyama, Kazuya; Khosravi, Nima E-mail: kazuya.koyama@port.ac.uk
2013-11-01
Gravitational vector degrees of freedom typically arise in many examples of modified gravity models. We start to systematically explore their role in these scenarios, studying the effects of coupling gravitational vector and scalar degrees of freedom. We focus on set-ups that enjoy a Galilean symmetry in the scalar sector and an Abelian gauge symmetry in the vector sector. These symmetries, together with the requirement that the equations of motion contain at most two space-time derivatives, only allow for a small number of operators in the Lagrangian for the gravitational fields. We investigate the role of gravitational vector fields for two broad classes of phenomena that characterize modified gravity scenarios. The first is self-acceleration: we analyze in general terms the behavior of vector fluctuations around self-accelerating solutions, and show that vanishing kinetic terms of vector fluctuations lead to instabilities on cosmological backgrounds. The second phenomenon is the screening of long range fifth forces by means of Vainshtein mechanism. We show that if gravitational vector fields are appropriately coupled to a spherically symmetric source, they can play an important role for defining the features of the background solution and the scale of the Vainshtein radius. Our general results can be applied to any concrete model of modified gravity, whose low-energy vector and scalar degrees of freedom satisfy the symmetry requirements that we impose.
Dust gravitational drift wave in complex plasma under gravity
Salahshoor, M. Niknam, A. R.
2014-12-15
The dispersion relation of electrostatic waves in a complex plasma under gravity is presented. It is assumed that the waves propagate parallel to the external fields. The effects of weak electric field, neutral drag force, and ion drag force are also taken into account. The dispersion relation is numerically examined in an appropriate parameter space in which the gravity plays the dominant role in the dynamics of microparticles. The numerical results show that, in the low pressure complex plasma under gravity, a low frequency drift wave can be developed in the long wavelength limit. The stability state of this wave is switched at a certain critical wavenumber in such a way that the damped mode is transformed into a growing one. Furthermore, the influence of the external fields on the dispersion properties is analyzed. It is shown that the wave instability is essentially due to the electrostatic streaming of plasma particles. It is also found that by increasing the electric field strength, the stability switching occurs at smaller wavenumbers.
McElfresh, Michael W.; (Livermore, CA); Lucas, Matthew S.; (Pasadena, CA)
2004-12-30
The present invention provides a membrane with magnetic particles. In one embodiment the membrane is created by mixing particles in a non-magnetic base. The membrane may act as an actuator, a sensor, a pump, a valve, or other device. A magnet is operatively connected to the membrane. The magnet acts on and changes the shape of the membrane.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zhu, S.; Cai, Y.; Rote, D. M.; Chen, S. S.
1998-01-01
Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.
Rayleigh-Taylor instabilities with sheared magnetic fields
Ruderman, M. S. [Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Terradas, J.; Ballester, J. L. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)
2014-04-20
Magnetic Rayleigh-Taylor (MRT) instabilities may play a relevant role in many astrophysical problems. In this work the effect of magnetic shear on the growth rate of the MRT instability is investigated. The eigenmodes of an interface and a slab model under the presence of gravity are analytically calculated assuming that the orientation of the magnetic field changes in the equilibrium, i.e., there is magnetic shear. We solve the linearized magnetohydrodynamic equations in the incompressible regime. We find that the growth rate is bounded under the presence of magnetic shear. We have derived simple analytical expressions for the maximum growth rate, corresponding to the most unstable mode of the system. These expressions provide the explicit dependence of the growth rate on the various equilibrium parameters. For small angles the growth time is linearly proportional to the shear angle, and in this regime the single interface problem and the slab problem tend to the same result. On the contrary, in the limit of large angles and for the interface problem the growth time is essentially independent of the shear angle. In this regime we have also been able to calculate an approximate expression for the growth time for the slab configuration. Magnetic shear can have a strong effect on the growth rates of the instability. As an application of the results found in this paper we have indirectly determined the shear angle in solar prominence threads using their lifetimes and the estimation of the Alfvén speed of the structure.
Constraints on a f(R) gravity dark energy model with early scaling evolution
Park, Chan-Gyung; Hwang, Jai-chan; Noh, Hyerim E-mail: jchan@knu.ac.kr
2011-09-01
The modified gravity with f(R) = R{sup 1+?} (? > 0) allows a scaling solution where the energy density of gravity sector follows the energy density of the dominant fluid. We present initial conditions of background and perturbation variables during the scaling evolution regime in the modified gravity. As a possible dark energy model we consider a gravity with a form f(R) = R{sup 1+?}+qR{sup ?n} (?1 < n ? 0) where the second term drives the late-time acceleration. We show that our f(R) gravity parameters are very sensitive to the baryon perturbation growth and baryon density power spectrum, and present observational constraints on the model parameters. We consider full perturbations of f(R) gravity. Our analysis suggests that only the parameter space extremely close to the ?CDM model is allowed with ??<5 × 10{sup ?6} and n?>?10{sup ?4}.
Nanocomposite Magnets: Transformational Nanostructured Permanent Magnets
2010-10-01
Broad Funding Opportunity Announcement Project: GE is using nanomaterials technology to develop advanced magnets that contain fewer rare earth materials than their predecessors. Nanomaterials technology involves manipulating matter at the atomic or molecular scale, which can represent a stumbling block for magnets because it is difficult to create a finely grained magnet at that scale. GE is developing bulk magnets with finely tuned structures using iron-based mixtures that contain 80% less rare earth materials than traditional magnets, which will reduce their overall cost. These magnets will enable further commercialization of HEVs, EVs, and wind turbine generators while enhancing U.S. competitiveness in industries that heavily utilize these alternatives to rare earth minerals.
Gravity Duals of Lifshitz-Like Fixed Points (Journal Article) | SciTech
Office of Scientific and Technical Information (OSTI)
Connect Gravity Duals of Lifshitz-Like Fixed Points Citation Details In-Document Search Title: Gravity Duals of Lifshitz-Like Fixed Points We find candidate macroscopic gravity duals for scale-invariant but non-Lorentz invariant fixed points, which do not have particle number as a conserved quantity. We compute two-point correlation functions which exhibit novel behavior relative to their AdS counterparts, and find holographic renormalization group flows to conformal field theories. Our
Magnetic switch coupling to synchronize magnetic modulators
Reed, Kim W. (Albuquerque, NM); Kiekel, Paul (Albuquerque, NM)
1999-01-01
Apparatus for synchronizing the output pulses from a pair of magnetic switches. An electrically conductive loop is provided between the pair of switches with the loop having windlings about the core of each of the magnetic switches. The magnetic coupling created by the loop removes voltage and timing variations between the outputs of the two magnetic switches caused by any of a variety of factors. The only remaining variation is a very small fixed timing offset caused by the geometry and length of the loop itself.
Magnetic switch coupling to synchronize magnetic modulators
Reed, K.W.; Kiekel, P.
1999-04-27
Apparatus for synchronizing the output pulses from a pair of magnetic switches is disclosed. An electrically conductive loop is provided between the pair of switches with the loop having windings about the core of each of the magnetic switches. The magnetic coupling created by the loop removes voltage and timing variations between the outputs of the two magnetic switches caused by any of a variety of factors. The only remaining variation is a very small fixed timing offset caused by the geometry and length of the loop itself. 13 figs.
Mueller, Fred M. (Los Alamos, NM); Bronisz, Lawrence (Los Alamos, NM); Grube, Holger (Los Alamos, NM); Nelson, David C. (Santa Fe, NM); Mace, Jonathan L. (Los Alamos, NM)
2006-11-14
A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.
Reduced Gravity Education Flight Opportunity for Students at Minority Serving Institutions
Broader source: Energy.gov [DOE]
NASA is offering undergraduate students from Minority Serving Institutions an opportunity to test experiments in microgravity aboard NASA's reduced gravity aircraft.
DETECTING GRAVITY MODES IN THE SOLAR {sup 8} B NEUTRINO FLUX
Lopes, Ilídio; Turck-Chièze, Sylvaine E-mail: ilopes@uevora.pt
2014-09-10
The detection of gravity modes produced in the solar radiative zone has been a challenge in modern astrophysics for more than 30 yr and their amplitude in the core is not yet determined. In this Letter, we develop a new strategy to look for standing gravity modes through solar neutrino fluxes. We note that due to a resonance effect, the gravity modes of low degree and low order have the largest impact on the {sup 8} B neutrino flux. The strongest effect is expected to occur for the dipole mode with radial order 2, corresponding to periods of about 1.5 hr. These standing gravity waves produce temperature fluctuations that are amplified by a factor of 170 in the boron neutrino flux for the corresponding period, in consonance with the gravity modes. From current neutrino observations, we determine that the maximum temperature variation due to the gravity modes in the Sun's core is smaller than 5.8 × 10{sup –4}. This study clearly shows that due to their high sensitivity to the temperature, the {sup 8} B neutrino flux time series is an excellent tool to determine the properties of gravity modes in the solar core. Moreover, if gravity mode footprints are discovered in the {sup 8} B neutrino flux, this opens a new line of research to probe the physics of the solar core as non-standing gravity waves of higher periods cannot be directly detected by helioseismology but could leave their signature on boron neutrino or on other neutrino fluxes.
Broader source: Energy.gov [DOE]
Integration of Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments for Simultaneous Data Acquisition presentation at the April 2013 peer review meeting held in Denver, Colorado.
Ground Gravity Survey At Salt Wells Area (Bureau of Land Management...
2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Salt Wells Area (Bureau of Land Management, 2009) Exploration...
Ground Gravity Survey At U.S. West Region (Aiken & Ander, 1981...
and southern Colorado References Carlos L.V. Aiken, Mark E. Ander (1981) A Regional Strategy For Geothermal Exploration With Emphasis On Gravity And Magnetotellurics Additional...
Ground Gravity Survey At Blue Mountain Geothermal Area (U.S....
search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Blue Mountain Geothermal Area (U.S. Geological Survey, 2012) Exploration Activity Details...
Ground Gravity Survey At Cove Fort Area (Toksoz, Et Al, 2010...
Exploration Activity Details Location Cove Fort Geothermal Area Exploration Technique Ground Gravity Survey Activity Date Usefulness not indicated DOE-funding Unknown Notes We...
Ground Gravity Survey At San Emidio Desert Area (DOE GTP) | Open...
Emidio Desert Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At San Emidio Desert Area (DOE GTP)...
Ground Gravity Survey At Maui Area (DOE GTP) | Open Energy Information
Maui Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Maui Area (DOE GTP) Exploration Activity Details...
Ground Gravity Survey At Raft River Geothermal Area (1957-1961...
search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Raft River Geothermal Area (1957-1961) Exploration Activity Details Location Raft River...
Tamper resistant magnetic stripes
Naylor, Richard Brian (Albuquerque, NM); Sharp, Donald J. (Albuquerque, NM)
1999-01-01
This invention relates to a magnetic stripe comprising a medium in which magnetized particles are suspended and in which the encoded information is recorded by actual physical rotation or alignment of the previously magnetized particles within the flux reversals of the stripe which are 180.degree. opposed in their magnetic polarity. The magnetized particles are suspended in a medium which is solid, or physically rigid, at ambient temperatures but which at moderately elevated temperatures, such as 40.degree. C., is thinable to a viscosity permissive of rotation of the particles therein under applications of moderate external magnetic field strengths within acceptable time limits.
Translation invariant time-dependent massive gravity: Hamiltonian analysis
Mourad, Jihad; Steer, Danièle A.; Noui, Karim E-mail: karim.noui@lmpt.univ-tours.fr
2014-09-01
The canonical structure of the massive gravity in the first order moving frame formalism is studied. We work in the simplified context of translation invariant fields, with mass terms given by general non-derivative interactions, invariant under the diagonal Lorentz group, depending on the moving frame as well as a fixed reference frame. We prove that the only mass terms which give 5 propagating degrees of freedom are the dRGT mass terms, namely those which are linear in the lapse. We also complete the Hamiltonian analysis with the dynamical evolution of the system.
Self-gravity in neutrino-dominated accretion disks
Liu, Tong; Yu, Xiao-Fei; Gu, Wei-Min; Lu, Ju-Fu
2014-08-10
We present the effects of self-gravity on the vertical structure and neutrino luminosity of the neutrino-dominated accretion disks in cylindrical coordinates. It is found that significant changes of the structure appear in the outer region of the disk, especially for high accretion rates (e.g., ? 1 M{sub ?} s{sup –1}), and thus cause the slight increase in the neutrino luminosity. Furthermore, the gravitational instability of the disk is reviewed by the vertical distribution of the Toomre parameter, which may account for the late-time flares in gamma-ray bursts and the extended emission in short-duration gamma-ray bursts.
Properties of solar gravity mode signals in total irradiance observations
Kroll, R.J.; Chen, J.; Hill, H.A.
1988-01-01
Further evidence has been found that a significant fraction of the gravity mode power density in the total irradiance observations appears in sidebands of classified eigenfrequencies. These sidebands whose amplitudes vary from year to year are interpreted as harmonics of the rotational frequencies of the nonuniform solar surface. These findings are for non axisymmetric modes and corroborate the findings of Kroll, Hill and Chen for axisymmetric modes. It is demonstrated the the generation of the sidebands lifts the usual restriction on the parity of the eigenfunctions for modes detectable in total irradiance observations. 14 refs.
Is Cosmic Acceleration Telling Us Something About Gravity?
Trodden, Mark [Syracuse University, Syracuse, New York, United States
2009-09-01
Among the possible explanations for the observed acceleration of the universe, perhaps the boldest is the idea that new gravitational physics might be the culprit. In this colloquium I will discuss some of the challenges of constructing a sensible phenomenological extension of General Relativity, give examples of some candidate models of modified gravity and survey existing observational constraints on this approach. I will conclude by discussing how we might hope to distinguish between modifications of General Relativity and dark energy as competing hypotheses to explain cosmic acceleration.
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging...
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in...
Tomisaka, Kohji
2014-04-10
Herschel observations have recently revealed that interstellar molecular clouds consist of many filaments. Polarization observations in optical and infrared wavelengths indicate that the magnetic field often runs perpendicular to the filament. In this article, we study the magnetohydrostatic configuration of isothermal gas in which the thermal pressure and the Lorentz force are balanced against the self-gravity, and the magnetic field is globally perpendicular to the axis of the filament. The model is controlled by three parameters: center-to-surface density ratio (? {sub c}/? {sub s}), plasma ? of surrounding interstellar gas (?{sub 0}), and the radius of the hypothetical parent cloud normalized by the scale-height (R{sub 0}{sup ?}), although there remains freedom in how the mass is distributed against the magnetic flux (mass loading). In the case where R{sub 0}{sup ?} is small enough, the magnetic field plays a role in confining the gas. However, the magnetic field generally has the effect of supporting the cloud. There is a maximum line-mass (mass per unit length) above which the cloud is not supported against gravity. Compared with the maximum line-mass of a nonmagnetized cloud (2c{sub s}{sup 2}/G, where c{sub s} and G represent, respectively, the isothermal sound speed and the gravitational constant), that of the magnetized filament is larger than the nonmagnetized one. The maximum line-mass is numerically obtained as ?{sub max}?0.24?{sub cl}/G{sup 1/2}+1.66c{sub s}{sup 2}/G, where ?{sub cl} represents one half of the magnetic flux threading the filament per unit length. The maximum mass of the filamentary cloud is shown to be significantly affected by the magnetic field when the magnetic flux per unit length exceeds ?{sub cl} ? 3 pc ?G (c{sub s} /190 m s{sup –1}){sup 2}.
Barclay, John A. (Los Alamos, NM); Steyert, William A. (Los Alamos, NM)
1982-01-01
The disclosure is directed to an active magnetic regenerator apparatus and method. Brayton, Stirling, Ericsson, and Carnot cycles and the like may be utilized in an active magnetic regenerator to provide efficient refrigeration over relatively large temperature ranges.
Confronting DGP braneworld gravity with cosmico observations after Planck data
Xu, Lixin
2014-02-01
The normal branch of Dvali-Gabadadze-Porrati braneworld gravity with brane tension is confronted by the currently available cosmic observations from the geometrical and dynamical perspectives. On the geometrical side, the type Ia supernova as standard candle, the baryon acoustic oscillation as standard ruler and the cosmic microwave background measurement from the first released 15.5 months data were used to fix the background evolutions. On the dynamical side, the redshift space distortion data will be used to determine the evolution of the matter perturbation. Through a Markov chain Monte Carlo analysis, we found the dimensionless crossover scale ?{sub r{sub c}} = 1/(4H{sup 2}{sub 0}r{sup 2}{sub c}) = 0.00183{sub ?0.00183}{sup +0.000338} in a spatially flat normal branch of Dvali-Gabadadze-Porrati braneworld. This result suggests that the crossover scale r{sub c} should be around 12H{sup ?1}{sub 0} which is consistent with the previous result r{sub c} > 3H{sup ?1}{sub 0} and greater. It also implies that the five-dimensional gravity effect is weak to be observed in H{sup ?1}{sub 0} scale.
Simulating the quartic Galileon gravity model on adaptively refined meshes
Li, Baojiu; Barreira, Alexandre; Baugh, Carlton M.; Hellwing, Wojciech A.; Koyama, Kazuya; Zhao, Gong-Bo; Pascoli, Silvia E-mail: baojiu.li@durham.ac.uk E-mail: wojciech.hellwing@durham.ac.uk E-mail: silvia.pascoli@durham.ac.uk
2013-11-01
We develop a numerical algorithm to solve the high-order nonlinear derivative-coupling equation associated with the quartic Galileon model, and implement it in a modified version of the ramses N-body code to study the effect of the Galileon field on the large-scale matter clustering. The algorithm is tested for several matter field configurations with different symmetries, and works very well. This enables us to perform the first simulations for a quartic Galileon model which provides a good fit to the cosmic microwave background (CMB) anisotropy, supernovae and baryonic acoustic oscillations (BAO) data. Our result shows that the Vainshtein mechanism in this model is very efficient in suppressing the spatial variations of the scalar field. However, the time variation of the effective Newtonian constant caused by the curvature coupling of the Galileon field cannot be suppressed by the Vainshtein mechanism. This leads to a significant weakening of the strength of gravity in high-density regions at late times, and therefore a weaker matter clustering on small scales. We also find that without the Vainshtein mechanism the model would have behaved in a completely different way, which shows the crucial role played by nonlinearities in modified gravity theories and the importance of performing self-consistent N-body simulations for these theories.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Cool Magnetic Molecules Cool Magnetic Molecules Print Wednesday, 25 May 2011 00:00 Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost
Combined passive magnetic bearing element and vibration damper
Post, Richard F. (Walnut Creek, CA)
2001-01-01
A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium and dampen transversely directed vibrations. Mechanical stabilizers are provided to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. In a improvement over U.S. Pat. No. 5,495,221, a magnetic bearing element is combined with a vibration damping element to provide a single upper stationary dual-function element. The magnetic forces exerted by such an element, enhances levitation of the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations, and suppresses the effects of unbalance or inhibits the onset of whirl-type rotor-dynamic instabilities. Concurrently, this equilibrium is made stable against displacement-dependent drag forces of the rotating object from its equilibrium position.
Magnetic nanohole superlattices
Liu, Feng
2013-05-14
A magnetic material is disclosed including a two-dimensional array of carbon atoms and a two-dimensional array of nanoholes patterned in the two-dimensional array of carbon atoms. The magnetic material has long-range magnetic ordering at a temperature below a critical temperature Tc.
Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert
2014-04-15
Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.
The cylindrical magnetic Rayleigh-Taylor instability for viscous fluids
Chambers, K.; Forbes, L. K.
2012-10-15
This paper considers a cylindrical Rayleigh-Taylor instability, in which a heavy fluid surrounds a light fluid, and gravity is directed radially inwards. A massive object is located at the centre of the light fluid, and it behaves like a line dipole both for fluid flow and magnetic field strength. The initially circular interface between the two conducting fluids evolves into plumes, dependent on the magnetic and fluid dipole strengths and the nature of the initial disturbance to the interface. A spectral method is presented to solve the time-dependent interface shapes, and results are presented and discussed. Bipolar solutions are possible, and these are of particular relevance to astrophysics. The solutions obtained resemble structures of some HII regions and nebulae.
Rotating superconductor magnet for producing rotating lobed magnetic field lines
Hilal, Sadek K. (Englewood Cliffs, NJ); Sampson, William B. (Bellport, NY); Leonard, Edward F. (Leonia, NJ)
1978-01-01
This invention provides a rotating superconductor magnet for producing a rotating lobed magnetic field, comprising a cryostat; a superconducting magnet in the cryostat having a collar for producing a lobed magnetic field having oppositely directed adjacent field lines; rotatable support means for selectively rotating the superconductor magnet; and means for energizing the superconductor magnet.
Magnetically attached sputter targets
Makowiecki, D.M.; McKernan, M.A.
1994-02-15
An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Jaffe, Todd
2012-01-01
Validation of Innovative Exploration Technologies for Newberry Volcano: Raw data used to prepare the Gravity Report by Zonge 2012
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Jaffe, Todd
Validation of Innovative Exploration Technologies for Newberry Volcano: Raw data used to prepare the Gravity Report by Zonge 2012
Translation invariant time-dependent solutions to massive gravity II
Mourad, J.; Steer, D.A. E-mail: steer@apc.univ-paris7.fr
2014-06-01
This paper is a sequel to JCAP 12 (2013) 004 and is also devoted to translation-invariant solutions of ghost-free massive gravity in its moving frame formulation. Here we consider a mass term which is linear in the vielbein (corresponding to a ?{sub 3} term in the 4D metric formulation) in addition to the cosmological constant. We determine explicitly the constraints, and from the initial value formulation show that the time-dependent solutions can have singularities at a finite time. Although the constraints give, as in the ?{sub 1} case, the correct number of degrees of freedom for a massive spin two field, we show that the lapse function can change sign at a finite time causing a singular time evolution. This is very different to the ?{sub 1} case where time evolution is always well defined. We conclude that the ?{sub 3} mass term can be pathological and should be treated with care.
Thermodynamic behavior of particular f(R,T)-gravity models
Sharif, M. Zubair, M.
2013-08-15
We investigate the thermodynamics at the apparent horizon of the FRW universe in f(R, T) theory in the nonequilibrium description. The laws of thermodynamics are discussed for two particular models of the f(R, T) theory. The first law of thermodynamics is expressed in the form of the Clausius relation T{sub h} dS-circumflex{sub h} = {delta} Q , where {delta}Q is the energy flux across the horizon and dS-circumflex is the entropy production term. Furthermore, the conditions for the generalized second law of thermodynamics to be preserved are established with the constraints of positive temperature and attractive gravity. We illustrate our results for some concrete models in this theory.
Phenomenology of electrostatically charged droplet combustion in normal gravity
Anderson, Eric K.; Koch, Jeremy A.; Kyritsis, Dimitrios C.
2008-08-15
Experimental findings are provided on the effect of electrostatically charging a fuel on single-burning droplet combustion in normal gravity. It was established that significant modification of the flame morphology and the droplet burning time could be achieved, solely by the droplet charge, without the application of external electric fields. Negative charging of the droplets of mixtures of isooctane with either ethanol or a commercially available anti-static additive generated intense motion of the flame and abbreviated the droplet burning time by as much as 40% for certain blend compositions. Positive charging of the droplets generated almost spherical flames, because electrostatic attraction toward the droplets countered the effect of buoyancy. By comparing combustion of droplets of the same conductivity but different compositions, coupling of electrostatics with combustion chemistry was established. (author)
The application of Raman laser in gravity measurement and metrology
Ru, Ning; Zhang, Li; Wang, Yu; Fan, Shangchun
2014-05-27
Atom Interferometry is proved to be a potential method for measuring the acceleration of atoms due to Gravity, we are now building a feasible system of cold atom gravimeter, it is based on the atom interferometry technology by coherently manipulating the cold atoms in a fountain (with a height of 1m) with specific Raman lasers, the cold atom wave packet is splitted, combined, and then re-splitted in the process. Then the atomic wave packet will acquire different phase because of the different evolution path. The precise acceleration can be deduced through the precision measurement of atomic interference fringes phase, and this will be a high precision standard of acceleration. At present, the preparation of Raman laser and the precise control of the laser Frequency have been finished, and they have been proved to meet the requirements of the experiment.
INTERNAL GRAVITY WAVES IN MASSIVE STARS: ANGULAR MOMENTUM TRANSPORT
Rogers, T. M.; Lin, D. N. C.; McElwaine, J. N.; Lau, H. H. B. E-mail: lin@ucolick.org E-mail: hblau@astro.uni-bonn.de
2013-07-20
We present numerical simulations of internal gravity waves (IGW) in a star with a convective core and extended radiative envelope. We report on amplitudes, spectra, dissipation, and consequent angular momentum transport by such waves. We find that these waves are generated efficiently and transport angular momentum on short timescales over large distances. We show that, as in Earth's atmosphere, IGW drive equatorial flows which change magnitude and direction on short timescales. These results have profound consequences for the observational inferences of massive stars, as well as their long term angular momentum evolution. We suggest IGW angular momentum transport may explain many observational mysteries, such as: the misalignment of hot Jupiters around hot stars, the Be class of stars, Ni enrichment anomalies in massive stars, and the non-synchronous orbits of interacting binaries.
Self-Consistent Cosmological Simulations of DGP Braneworld Gravity
Schmidt, Fabian; /Chicago U., Astron. Astrophys. Ctr. /KICP, Chicago
2009-09-01
We perform cosmological N-body simulations of the Dvali-Gabadadze-Porrati braneworld model, by solving the full non-linear equations of motion for the scalar degree of freedom in this model, the brane bending mode. While coupling universally to matter, the brane-bending mode has self-interactions that become important as soon as the density field becomes non-linear. These self-interactions lead to a suppression of the field in high-density environments, and restore gravity to General Relativity. The code uses a multi-grid relaxation scheme to solve the non-linear field equation in the quasi-static approximation. We perform simulations of a flat self-accelerating DGP model without cosmological constant. However, the type of non-linear interactions of the brane-bending mode, which are the focus of this study, are generic to a wide class of braneworld cosmologies. The results of the DGP simulations are compared with standard gravity simulations assuming the same expansion history, and with DGP simulations using the linearized equation for the brane bending mode. This allows us to isolate the effects of the non-linear self-couplings of the field which are noticeable already on quasi-linear scales. We present results on the matter power spectrum and the halo mass function, and discuss the behavior of the brane bending mode within cosmological structure formation. We find that, independently of CMB constraints, the self-accelerating DGP model is strongly constrained by current weak lensing and cluster abundance measurements.
Gent, F. A.; Erdélyi, R.; Fedun, V.
2014-07-01
A system of multiple open magnetic flux tubes spanning the solar photosphere and lower corona is modeled analytically, within a realistic stratified atmosphere subject to solar gravity. This extends results for a single magnetic flux tube in magnetohydrostatic equilibrium, described in Gent et al. Self-similar magnetic flux tubes are combined to form magnetic structures, which are consistent with high-resolution observations. The observational evidence supports the existence of strands of open flux tubes and loops persisting in a relatively steady state. Self-similar magnetic flux tubes, for which an analytic solution to the plasma density and pressure distribution is possible, are combined. We calculate the appropriate balancing forces, applying to the equations of momentum and energy conservation to preserve equilibrium. Multiplex flux tube configurations are observed to remain relatively stable for up to a day or more, and it is our aim to apply our model as the background condition for numerical studies of energy transport mechanisms from the solar surface to the corona. We apply magnetic field strength, plasma density, pressure, and temperature distributions consistent with observational and theoretical estimates for the lower solar atmosphere. Although each flux tube is identical in construction apart from the location of the radial axis, combinations can be applied to generate a non-axisymmetric magnetic field with multiple non-uniform flux tubes. This is a considerable step forward in modeling the realistic magnetized three-dimensional equilibria of the solar atmosphere.
Testing universal relations of neutron stars with a nonlinear matter-gravity coupling theory
Sham, Y.-H.; Lin, L.-M.; Leung, P. T. E-mail: lmlin@phy.cuhk.edu.hk
2014-02-01
Due to our ignorance of the equation of state (EOS) beyond nuclear density, there is still no unique theoretical model for neutron stars (NSs). It is therefore surprising that universal EOS-independent relations connecting different physical quantities of NSs can exist. Lau et al. found that the frequency of the f-mode oscillation, the mass, and the moment of inertia are connected by universal relations. More recently, Yagi and Yunes discovered the I-Love-Q universal relations among the mass, the moment of inertia, the Love number, and the quadrupole moment. In this paper, we study these universal relations in the Eddington-inspired Born-Infeld (EiBI) gravity. This theory differs from general relativity (GR) significantly only at high densities due to the nonlinear coupling between matter and gravity. It thus provides us an ideal case to test how robust the universal relations of NSs are with respect to the change of the gravity theory. Due to the apparent EOS formulation of EiBI gravity developed recently by Delsate and Steinhoff, we are able to study the universal relations in EiBI gravity using the same techniques as those in GR. We find that the universal relations in EiBI gravity are essentially the same as those in GR. Our work shows that, within the currently viable coupling constant, there exists at least one modified gravity theory that is indistinguishable from GR in view of the unexpected universal relations.
Nanoscale, multidimensional artificial magnet created
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Nanoscale, multidimensional artificial magnet created Nanoscale, multidimensional artificial magnet created Applications might range from general magnetism, such as developing sensors, to information encoding. October 26, 2015 Researchers have created a nanoscale, artificial magnet by arranging an array of magnetic nano-islands along a geometry that is not found in natural magnets. As temperature is reduced, magnetic nanoislands (in blue) reach a one-dimensional static, ordered state, while
Passive magnetic bearing system
Post, Richard F.
2014-09-02
An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.
Christiansen, D.W.; Brown, W.F.
1984-01-01
A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.
Marts, D.J.; Richardson, J.G.; Albano, R.K.; Morrison, J.L. Jr.
1995-11-28
This invention discloses a D.C. magnetic latching solenoid that retains a moving armature in a first or second position by means of a pair of magnets, thereby having a zero-power requirement after actuation. The first or second position is selected by reversing the polarity of the D.C. voltage which is enough to overcome the holding power of either magnet and transfer the armature to an opposite position. The coil is then de-energized. 2 figs.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability
Marts, Donna J. (Idaho Falls, ID); Richardson, John G. (Idaho Falls, ID); Albano, Richard K. (Idaho Falls, ID); Morrison, Jr., John L. (Idaho Falls, ID)
1995-01-01
This invention discloses a D.C. magnetic latching solenoid that retains a moving armature in a first or second position by means of a pair of magnets, thereby having a zero-power requirement after actuation. The first or second position is selected by reversing the polarity of the D.C. voltage which is enough to overcome the holding power of either magnet and transfer the armature to an opposite position. The coil is then de-energized.
How Does Gravity Work to Hold a Human Down? | GE Global Research
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Does Gravity Work to Hold a Human Down? Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new window) Click to share on LinkedIn (Opens in new window) Click to share on Tumblr (Opens in new window) How Does Gravity Work to Hold a Human Down? 2012.04.13 Chief Scientist Jim Bray discusses how velocity and gravity affect space travel. 0 Comments Comment Name Email Submit Comment You Might Also Like Lucas_Malta_airplane_V Green
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Conversely, introducing a magnetic field to certain materials will cause the material to heat up. This happens because, as the spins in such (paramagnetic) materials align with...
Magnetically leviated superconducting bearing
Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT)
1993-01-01
A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.
Passive magnetic bearing configurations
Post, Richard F. (Walnut Creek, CA)
2011-01-25
A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.
Generalised BRST symmetry and gaugeon formalism for perturbative quantum gravity: Novel observation
Upadhyay, Sudhaker
2014-05-15
In this paper the novel features of Yokoyama gaugeon formalism are stressed out for the theory of perturbative quantum gravity in the Einstein curved spacetime. The quantum gauge transformations for the theory of perturbative gravity are demonstrated in the framework of gaugeon formalism. These quantum gauge transformations lead to renormalised gauge parameter. Further, we analyse the BRST symmetric gaugeon formalism which embeds more acceptable Kugo–Ojima subsidiary condition. Further, the BRST symmetry is made finite and field-dependent. Remarkably, the Jacobian of path integral under finite and field-dependent BRST symmetry amounts to the exact gaugeon action in the effective theory of perturbative quantum gravity. -- Highlights: •We analyse the perturbative gravity in gaugeon formalism. •The generalisation of BRST transformation is also studied in this context. •Within the generalised BRST framework we found the exact gaugeon modes in the theory.
Table 23. Domestic Crude Oil First Purchase Prices by API Gravity
U.S. Energy Information Administration (EIA) Indexed Site
18.62 19.26 Source: Energy Information Administration, Form EIA-182, "Domestic Crude Oil First Purchase Report." 23. Domestic Crude Oil First Purchase Prices by API Gravity Energy...
Table 23. Domestic Crude Oil First Purchase Prices by API Gravity
U.S. Energy Information Administration (EIA) Indexed Site
20.23 20.91 Source: Energy Information Administration, Form EIA-182, "Domestic Crude Oil First Purchase Report." 23. Domestic Crude Oil First Purchase Prices by API Gravity Energy...
Gravity survey of Dixie Valley, west-central Nevada | Open Energy...
to library Report: Gravity survey of Dixie Valley, west-central Nevada Author Donald H. Schaefer Published US Geological Survey, 1983 Report Number 82-111 DOI Not Provided...
Violation of the first law of black hole thermodynamics in f(T) gravity
Miao, Rong-Xin; Li, Miao; Miao, Yan-Gang E-mail: mli@itp.ac.cn
2011-11-01
We prove that, in general, the first law of black hole thermodynamics, ?Q = T?S, is violated in f(T) gravity. As a result, it is possible that there exists entropy production, which implies that the black hole thermodynamics can be in non-equilibrium even in the static spacetime. This feature is very different from that of f(R) or that of other higher derivative gravity theories. We find that the violation of first law results from the lack of local Lorentz invariance in f(T) gravity. By investigating two examples, we note that f''(0) should be negative in order to avoid the naked singularities and superluminal motion of light. When f''(T) is small, the entropy of black holes in f(T) gravity is approximatively equal to f'(T)/4 A.
Toward the AdS/CFT gravity dual for high energy collisions. II...
Office of Scientific and Technical Information (OSTI)
II. The stress tensor on the boundary Citation Details In-Document Search Title: Toward the AdSCFT gravity dual for high energy collisions. II. The stress tensor on the boundary ...
Mirzatuny, Nareg; Khosravi, Shahram; Baghram, Shant; Moshafi, Hossein E-mail: khosravi@mail.ipm.ir E-mail: hosseinmoshafi@iasbs.ac.ir
2014-01-01
In this work we study the simultaneous effect of primordial non-Gaussianity and the modification of the gravity in f(R) framework on large scale structure observations. We show that non-Gaussianity and modified gravity introduce a scale dependent bias and growth rate functions. The deviation from ?CDM in the case of primordial non-Gaussian models is in large scales, while the growth rate deviates from ?CDM in small scales for modified gravity theories. We show that the redshift space distortion can be used to distinguish positive and negative f{sub NL} in standard background, while in f(R) theories they are not easily distinguishable. The galaxy power spectrum is generally enhanced in presence of non-Gaussianity and modified gravity. We also obtain the scale dependence of this enhancement. Finally we define galaxy growth rate and galaxy growth rate bias as new observational parameters to constrain cosmology.
Ground Gravity Survey At Cove Fort Area (Warpinski, Et Al., 2004...
Ground Gravity Survey Activity Date Usefulness not indicated DOE-funding Unknown Notes Update to Warpinski, et al., 2002 References N. R. Warpinski, A. R. Sattler, R. Fortuna, D....
Novel magnets and superconductors studied by high precision magnetic...
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Novel magnets and superconductors studied by high precision magnetic susceptometer under pressure An Inductor-capacitor circuit (LC circuit) is a simple, text-book level electric...
Strain-assisted current-induced magnetization reversal in magnetic...
Office of Scientific and Technical Information (OSTI)
Strain-assisted current-induced magnetization reversal in magnetic tunnel junctions: A micromagnetic study with phase-field microelasticity Citation Details In-Document Search ...
Thorn, C.E.; Chasman, C.; Baltz, A.J.
1981-11-19
An improved magnet more easily provides a radially increasing magnetic field, as well as reduced fringe field and requires less power for a given field intensity. The subject invention comprises a pair of spaced, opposed magnetic poles which further comprise a pair of pole roots, each having a pole tip attached to its center. The pole tips define the gap between the magnetic poles and at least a portion of each pole tip is separated from its associated pole root. The separation begins at a predetermined distance from the center of the pole root and increases with increasing radial distance while being constant with azimuth within that portion. Magnets in accordance with the subject invention have been found to be particularly advantageous for use in large isochronous cyclotrons.
Thorn, Craig E. (Wading River, NY); Chasman, Chellis (Setauket, NY); Baltz, Anthony J. (Coram, NY)
1984-04-24
An improved magnet which more easily provides a radially increasing magnetic field, as well as reduced fringe field and requires less power for a given field intensity. The subject invention comprises a pair of spaced, opposed magnetic poles which further comprise a pair of pole roots, each having a pole tip attached to its center. The pole tips define the gap between the magnetic poles and at least a portion of each pole tip is separated from its associated pole root. The separation begins at a predetermined distance from the center of the pole root and increases with increasing radial distance while being constant with azimuth within that portion. Magnets in accordance with the subject invention have been found to be particularly advantageous for use in large isochronous cyclotrons.
New Cosmologies on the Horizon. Cosmology and Holography in bigravity and massive gravity
Tolley, Andrew James
2013-03-31
The goal of this research program is to explore the cosmological dynamics, the nature of cosmological and black hole horizons, and the role of holography in a new class of infrared modified theories of gravity. This will capitalize of the considerable recent progress in our understanding of the dynamics of massive spin two fields on curved spacetimes, culminating in the formulation of the first fully consistent theories of massive gravity and bigravity/bimetric theories.
Pure gravity mediation and spontaneous B-L breaking from strong dynamics
Office of Scientific and Technical Information (OSTI)
(Journal Article) | DOE PAGES Pure gravity mediation and spontaneous B-L breaking from strong dynamics Â« Prev Next Â» Title: Pure gravity mediation and spontaneous B-L breaking from strong dynamics Authors: Babu, Kaladi S. ; Schmitz, Kai ; Yanagida, Tsutomu T. Publication Date: 2016-04-01 OSTI Identifier: 1236278 Grant/Contract Number: SC0010108 Type: Published Article Journal Name: Nuclear Physics. B Additional Journal Information: Journal Volume: 905; Journal Issue: C; Journal ID: ISSN
Borehole Gravity Meter Surveys at the Waste Treatment Plant, Hanford, Washington.
MacQueen, Jeffrey D.; Mann, Ethan
2007-04-06
Microg-LaCoste (MGL) was contracted by Pacfic Northwest National Laboratories (PNNL) to record borehole gravity density data in 3 wells at the HanfordWaste Treatment Plant (WTP) site. The survey was designed to provide highly accurate density information for use in seismic modeling. The borehole gravity meter (BHGM) tool has a very large depth of investigation (hundreds of feet) compared to other density tools so it is not influenced by casing or near welbore effects, such as washouts.
Topological black holes in Lovelock-Born-Infeld gravity
Dehghani, M. H.; Alinejadi, N.; Hendi, S. H.
2008-05-15
In this paper, we present topological black holes of third order Lovelock gravity in the presence of cosmological constant and nonlinear electromagnetic Born-Infeld field. Depending on the metric parameters, these solutions may be interpreted as black hole solutions with inner and outer event horizons, an extreme black hole or naked singularity. We investigate the thermodynamics of asymptotically flat solutions and show that the thermodynamic and conserved quantities of these black holes satisfy the first law of thermodynamic. We also endow the Ricci flat solutions with a global rotation and calculate the finite action and conserved quantities of these class of solutions by using the counterterm method. We compute the entropy through the use of the Gibbs-Duhem relation and find that the entropy obeys the area law. We obtain a Smarr-type formula for the mass as a function of the entropy, the angular momenta, and the charge, and compute temperature, angular velocities, and electric potential and show that these thermodynamic quantities coincide with their values which are computed through the use of geometry. Finally, we perform a stability analysis for this class of solutions in both the canonical and the grand-canonical ensemble and show that the presence of a nonlinear electromagnetic field and higher curvature terms has no effect on the stability of the black branes, and they are stable in the whole phase space.
Mass gap for gravity localized on Weyl thick branes
Barbosa-Cendejas, N.; Santos, M. A. Reyes; Herrera-Aguilar, A.; Schubert, C.
2008-06-15
We consider thick brane configurations in a pure geometric Weyl integrable 5D space-time, a non-Riemannian generalization of Kaluza-Klein (KK) theory involving a geometric scalar field. Thus, the 5D theory describes gravity coupled to a self-interacting scalar field which gives rise to the structure of the thick branes. We continue the study of the properties of a previously found family of solutions which is smooth at the position of the brane but involves naked singularities in the fifth dimension. Analyzing their graviton spectrum, we find that a particularly interesting situation arises for a special case in which the 4D graviton is separated from the KK gravitons by a mass gap. The corresponding effective Schroedinger equation has a modified Poeschl-Teller potential and can be solved exactly. Apart from the massless 4D graviton, it contains one massive KK bound state, and the continuum spectrum of delocalized KK modes. We also discuss the mass hierarchy problem, and explicitly compute the corrections to Newton's law in the thin brane limit.
Asymptotically flat radiating solutions in third order Lovelock gravity
Dehghani, M. H.; Farhangkhah, N.
2008-09-15
In this paper, we present an exact spherically symmetric solution of third order Lovelock gravity in n dimensions which describes the gravitational collapse of a null dust fluid. This solution is asymptotically (anti-)de Sitter or flat depending on the choice of the cosmological constant. Using the asymptotically flat solution for n{>=}7 with a power-law form of the mass as a function of the null coordinate, we present a model for a gravitational collapse in which a null dust fluid radially injects into an initially flat and empty region. It is found that a naked singularity is inevitably formed whose strength is different for the n=7 and n{>=}8 cases. In the n=7 case, the limiting focusing condition for the strength of curvature singularity is satisfied. But for n{>=}8, the strength of curvature singularity depends on the rate of increase of mass of the spacetime. These considerations show that the third order Lovelock term weakens the strength of the curvature singularity.
Avoidance of singularities in asymptotically safe Quantum Einstein Gravity
Kofinas, Georgios; Zarikas, Vasilios
2015-10-30
New general spherically symmetric solutions have been derived with a cosmological â€œconstantâ€ Î› as a source. This Î› term is not constant but it satisfies the properties of the asymptotically safe gravity at the ultraviolet fixed point. The importance of these solutions comes from the fact that they may describe the near to the centre region of black hole spacetimes as this is modified by the Renormalization Group scaling behaviour of the fields. The consistent set of field equations which respect the Bianchi identities is derived and solved. One of the solutions (with conventional sign of temporal-radial metric components) is timelike geodesically complete, and although there is still a curvature divergent origin, this is never approachable by an infalling massive particle which is reflected at a finite distance due to the repulsive origin. Another family of solutions (of both signatures) range from a finite radius outwards, they cannot be extended to the centre of spherical symmetry, and the curvature invariants are finite at the minimum radius.
Generalized second law of thermodynamics in f(T) gravity
Karami, K.; Abdolmaleki, A. E-mail: AAbdolmaleki@uok.ac.ir
2012-04-01
We investigate the validity of the generalized second law (GSL) of gravitational thermodynamics in the framework of f(T) modified teleparallel gravity. We consider a spatially flat FRW universe containing only the pressureless matter. The boundary of the universe is assumed to be enclosed by the Hubble horizon. For two viable f(T) models containing f(T) = T+?{sub 1}((?T)){sup n} and f(T) = T??{sub 2}T(1?e{sup ?T{sub 0}/T}), we first calculate the effective equation of state and deceleration parameters. Then, (we investigate the null and strong energy conditions and conclude that a sudden future singularity appears in both models. Furthermore, using a cosmographic analysis we check the viability of two models. Finally, we examine the validity of the GSL and find that for both models it) is satisfied from the early times to the present epoch. But in the future, the GSL is violated for the special ranges of the torsion scalar T.
Can f(T) gravity theories mimic ?CDM cosmic history
Setare, M.R.; Mohammadipour, N. E-mail: N.Mohammadipour@uok.ac.ir
2013-01-01
Recently the teleparallel Lagrangian density described by the torsion scalar T has been extended to a function of T. The f(T) modified teleparallel gravity has been proposed as the natural gravitational alternative for dark energy to explain the late time acceleration of the universe. In order to reconstruct the function f(T) by demanding a background ?CDM cosmology we assume that, (i) the background cosmic history provided by the flat ?CDM (the radiation ere with ?{sub eff} = (1/3), matter and de Sitter eras with ?{sub eff} = 0 and ?{sub eff} = ?1, respectively) (ii) the radiation dominate in the radiation era with ?{sub 0r} = 1 and the matter dominate during the matter phases when ?{sub 0m} = 1. We find the cosmological dynamical system which can obey the ?CDM cosmic history. In each era, we find a critical lines that, the radiation dominated and the matter dominated are one points of them in the radiation and matter phases, respectively. Also, we drive the cosmologically viability condition for these models. We investigate the stability condition with respect to the homogeneous scalar perturbations in each era and we obtain the stability conditions for the fixed points in each eras. Finally, we reconstruct the function f(T) which mimics cosmic expansion history.
Lensless Imaging of Magnetic Nanostructures
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Lensless Imaging of Magnetic Nanostructures Lensless Imaging of Magnetic Nanostructures Print Wednesday, 28 March 2012 00:00 Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the
Slowly rotating neutron and strange stars in R{sup 2} gravity
Staykov, Kalin V.; Yazadjiev, Stoytcho S.; Doneva, Daniela D.; Kokkotas, Kostas D. E-mail: daniela.doneva@uni-tuebingen.de E-mail: kostas.kokkotas@uni-tuebingen.de
2014-10-01
In the present paper we investigate self-consistently slowly rotating neutron and strange stars in R-squared gravity with Lagrangian f(R) = R + aR{sup 2}, where a is a parameter. For this purpose we first derive the equations describing the structure of the slowly rotating compact stars in f(R)-gravity and then simultaneously solve numerically the exterior and the interior problem. The structure of the slowly rotating neutron stars is studied for two different hadronic equations of state and a strange matter equation of state. The moment of inertia and its dependence on the stellar mass and the R-squared gravity parameter a is also examined in details. The numerical results show that the neutron star moment of inertia can be up to 30% larger compared to the corresponding general relativistic models. This is much higher than the change in the maximum mass induced by R-squared gravity and is beyond the EOS uncertainty. In this way the future observations of the moment of inertia of compact stars could allow us to distinguish between general relativity and f(R) gravity, and more generally to test the strong field regime of gravity.
Lensless Imaging of Magnetic Nanostructures
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useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism,...
Lensless Imaging of Magnetic Nanostructures
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the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies....
Large Magnetization at Carbon Surfaces
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Large Magnetization at Carbon Surfaces Large Magnetization at Carbon Surfaces Print Wednesday, 31 August 2011 00:00 From organic matter to pencil lead, carbon is a versatile...
Speed Limit of Magnetic Recording
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from the original magnetization direction can be distinguished as changes in the grey scale contrast. In our images the original magnetization direction corresponds to light...
PLUTONIUM OUGHT TO PRODUCE MAGNETISM.
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... valence states. 1663 October 2015 5 electrical conductivity changes drastically in the presence of a magnetic field, allowing for new spintronic and magnetic- sensing devices. ...
Large Magnetization at Carbon Surfaces
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exist even at room temperature. This makes carbon's magnetism an interesting natural effect with potential real-world applications if samples are thin enough. Magnetic hysteresis...
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important...
Magnetic Refrigeration | GE Global Research
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Johnson, a materials scientist and project leader on GE's magnetic refrigeration project. ... materials would further improve the competitiveness of magnetic refrigeration technology. ...
Lensless Imaging of Magnetic Nanostructures
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Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying...
Krienin, Frank (Shoreham, NY)
1990-01-01
A magnetic field generating device provides a useful magnetic field within a specific retgion, while keeping nearby surrounding regions virtually field free. By placing an appropriate current density along a flux line of the source, the stray field effects of the generator may be contained. One current carrying structure may support a truncated cosine distribution, and it may be surrounded by a current structure which follows a flux line that would occur in a full coaxial double cosine distribution. Strong magnetic fields may be generated and contained using superconducting cables to approximate required current surfaces.
Bonanos, Peter (East Brunswick, NJ)
1983-01-01
A toroidal magnet for confining a high magnetic field for use in fusion reactor research and nuclear particle detection. The magnet includes a series of conductor elements arranged about and fixed at its small major radius portion to the outer surface of a central cylindrical support each conductor element having a geometry such as to maintain the conductor elements in pure tension when a high current flows therein, and a support assembly which redistributes all or part of the tension which would otherwise arise in the small major radius portion of each coil element to the large major radius portion thereof.
Permanent magnet energy conversion machine with magnet mounting arrangement
Hsu, John S. (Oak Ridge, TN); Adams, Donald J. (Knoxville, TN)
1999-01-01
A hybrid permanent magnet dc motor includes three sets of permanent magnets supported by the rotor and three sets of corresponding stators fastened to the surrounding frame. One set of magnets operates across a radial gap with a surrounding radial gap stator, and the other two sets of magnets operate off the respective ends of the rotor across respective axial gaps.
Gravity waves from non-minimal quadratic inflation
Pallis, Constantinos; Shafi, Qaisar
2015-03-12
We discuss non-minimal quadratic inflation in supersymmetric (SUSY) and non-SUSY models which entails a linear coupling of the inflaton to gravity. Imposing a lower bound on the parameter c{sub R}, involved in the coupling between the inflaton and the Ricci scalar curvature, inflation can be attained even for subplanckian values of the inflaton while the corresponding effective theory respects the perturbative unitarity up to the Planck scale. Working in the non-SUSY context we also consider radiative corrections to the inflationary potential due to a possible coupling of the inflaton to bosons or fermions. We find ranges of the parameters, depending mildly on the renormalization scale, with adjustable values of the spectral index n{sub s}, tensor-to-scalar ratio râ‰ƒ(2âˆ’4)â‹…10{sup âˆ’3}, and an inflaton mass close to 3â‹…10{sup 13} GeV. In the SUSY framework we employ two gauge singlet chiral superfields, a logarithmic KÃ¤hler potential including all the allowed terms up to fourth order in powers of the various fields, and determine uniquely the superpotential by applying a continuous R and a global U(1) symmetry. When the KÃ¤hler manifold exhibits a no-scale-type symmetry, the model predicts n{sub s}â‰ƒ0.963 and râ‰ƒ0.004. Beyond no-scale SUGRA, n{sub s} and r depend crucially on the coefficient involved in the fourth order term, which mixes the inflaton with the accompanying non-inflaton field in the KÃ¤hler potential, and the prefactor encountered in it. Increasing slightly the latter above (âˆ’3), an efficient enhancement of the resulting r can be achieved putting it in the observable range. The inflaton mass in the last case is confined in the range (5âˆ’9)â‹…10{sup 13} GeV.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
4-ID-C: Soft X-ray Magnetic Spectroscopy This beamline operates in the soft x-ray energy spectrum (500 - 2700 eV) using an electromagnetic helical undulator to provide circularly...
Meyer, R.E.
1993-03-09
A climbing apparatus is provided for climbing ferromagnetic surfaces, such as storage tanks and steel frame structures. A magnet assembly is rotatably mounted in a frame assembly. The frame assembly provides a pair of cam surfaces having different dimensions so that, when the frame is rotated, the cam surfaces contact the ferromagnetic surface to separate the magnet assembly from the surface. The different cam dimensions enable one side of the magnet at a time to be detached from the surface to reduce the effort needed to disengage the climbing apparatus. The cam surface also provides for smoothly attaching the apparatus. A hardened dowel pin is also attached to the frame and the pointed end of the dowel engages the surface when the magnet is attached to the surface to prevent downward sliding movement of the assembly under the weight of the user.
Meyer, Ross E. (Los Alamos, NM)
1993-01-01
A climbing apparatus is provided for climbing ferromagnetic surfaces, such as storage tanks and steel frame structures. A magnet assembly is rotatably mounted in a frame assembly. The frame assembly provides a pair of cam surfaces having different dimensions so that, when the frame is rotated, the cam surfaces contact the ferromagnetic surface to separate the magnet assembly from the surface. The different cam dimensions enable one side of the magnet at a time to be detached from the surface to reduce the effort needed to disengage the climbing apparatus. The cam surface also provides for smoothly attaching the apparatus. A hardened dowel pin is also attached to the frame and the pointed end of the dowel engages the surface when the magnet is attached to the surface to prevent downward sliding movement of the assembly under the weight of the user.
Modular tokamak magnetic system
Yang, Tien-Fang (Wayland, MA)
1988-01-01
A modular tokamak system comprised of a plurality of interlocking moldules. Each module is comprised of a vacuum vessel section, a toroidal field coil, moldular saddle coils which generate a poloidal magnetic field and ohmic heating coils.
Universality of the acceleration due to gravity on the surface of a rapidly rotating neutron star
AlGendy, Mohammad; Morsink, Sharon M.
2014-08-20
On the surface of a rapidly rotating neutron star, the effective centrifugal force decreases the effective acceleration due to gravity (as measured in the rotating frame) at the equator while increasing the acceleration at the poles due to the centrifugal flattening of the star into an oblate spheroid. We compute the effective gravitational acceleration for relativistic rapidly rotating neutron stars and show that for a star with mass M, equatorial radius R{sub e} , and angular velocity ?, the deviations of the effective acceleration due to gravity from the nonrotating case take on a universal form that depends only on the compactness ratio M/R{sub e} , the dimensionless square of the angular velocity ?{sup 2}R{sub e}{sup 3}/GM, and the latitude on the star's surface. This dependence is universal, in that it has very little dependence on the neutron star's equation of state. The effective gravity is expanded in the slow-rotation limit to show the dependence on the effective centrifugal force, oblate shape of the star, and the quadrupole moment of the gravitational field. In addition, an empirical fit and simple formula for the effective gravity is found. We find that the increase in the acceleration due to gravity at the poles is of the same order of magnitude as the decrease in the effective acceleration due to gravity at the equator for all realistic value of mass, radius, and spin. For neutron stars that spin with frequencies near 600 Hz, the difference between the effective gravity at the poles and the equator is about 20%.
A Sea Floor Gravity Survey of the Sleipner Field to Monitor CO2 Migration
Mark Zumberge
2011-09-30
Carbon dioxide gas (CO{sub 2}) is a byproduct of many wells that produce natural gas. Frequently the CO{sub 2} separated from the valuable fossil fuel gas is released into the atmosphere. This adds to the growing problem of the climatic consequences of greenhouse gas contamination. In the Sleipner North Sea natural gas production facility, the separated CO{sub 2} is injected into an underground saline aquifer to be forever sequestered. Monitoring the fate of such sequestered material is important - and difficult. Local change in Earth's gravity field over the injected gas is one way to detect the CO{sub 2} and track its migration within the reservoir over time. The density of the injected gas is less than that of the brine that becomes displaced from the pore space of the formation, leading to slight but detectable decrease in gravity observed on the seafloor above the reservoir. Using equipment developed at Scripps Institution of Oceanography, we have been monitoring gravity over the Sleipner CO{sub 2} sequestration reservoir since 2002. We surveyed the field in 2009 in a project jointly funded by a consortium of European oil and gas companies and the US Department of Energy. The value of gravity at some 30 benchmarks on the seafloor, emplaced at the beginning of the monitoring project, was observed in a week-long survey with a remotely operated vehicle. Three gravity meters were deployed on the benchmarks multiple times in a campaign-style survey, and the measured gravity values compared to those collected in earlier surveys. A clear signature in the map of gravity differences is well correlated with repeated seismic surveys.
Berman, S.M.; Richardson R.W.
1983-12-29
The radiant emission of a mercury-argon discharge in a fluorescent lamp assembly is enhanced by providing means for establishing a magnetic field with lines of force along the path of electron flow through the bulb of the lamp assembly, to provide Zeeman splitting of the ultraviolet spectral line. Optimum results are obtained when the magnetic field strength causes a Zeeman splitting of approximately 1.7 times the thermal line width.
Nance, Thomas A. (Aiken, SC)
2009-08-18
A quick connect/disconnect coupling apparatus is provided in which a base member is engaged by a locking housing through a series of interengagement pins. The pins maintain the shaft in a locked position. Upon exposure to an appropriately positioned magnetic field, pins are removed a sufficient distance such that the shaft may be withdrawn from the locking housing. The ability to lock and unlock the connector assembly requires no additional tools or parts apart from a magnetic key.
Permanent Magnet Ecr Plasma Source With Magnetic Field Optimization
Doughty, Frank C. (Plano, TX); Spencer, John E. (Plano, TX)
2000-12-19
In a plasma-producing device, an optimized magnet field for electron cyclotron resonance plasma generation is provided by a shaped pole piece. The shaped pole piece adjusts spacing between the magnet and the resonance zone, creates a convex or concave resonance zone, and decreases stray fields between the resonance zone and the workpiece. For a cylindrical permanent magnet, the pole piece includes a disk adjacent the magnet together with an annular cylindrical sidewall structure axially aligned with the magnet and extending from the base around the permanent magnet. The pole piece directs magnetic field lines into the resonance zone, moving the resonance zone further from the face of the magnet. Additional permanent magnets or magnet arrays may be utilized to control field contours on a local scale. Rather than a permeable material, the sidewall structure may be composed of an annular cylindrical magnetic material having a polarity opposite that of the permanent magnet, creating convex regions in the resonance zone. An annular disk-shaped recurve section at the end of the sidewall structure forms magnetic mirrors keeping the plasma off the pole piece. A recurve section composed of magnetic material having a radial polarity forms convex regions and/or magnetic mirrors within the resonance zone.
ZALIZNYAK,I.A.; LEE,S.H.
2004-07-30
Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern science, ranging from large-scale structures and dynamics of polymers and biological systems, to electronic properties of today's technological materials. Neutron scattering developed into a vast field, encompassing many different experimental techniques aimed at exploring different aspects of matter's atomic structure and dynamics. Modern magnetic neutron scattering includes several specialized techniques designed for specific studies and/or particular classes of materials. Among these are magnetic reflectometry aimed at investigating surfaces, interfaces, and multilayers, small-angle scattering for the large-scale structures, such as a vortex lattice in a superconductor, and neutron spin-echo spectroscopy for glasses and polymers. Each of these techniques and many others offer exciting opportunities for examining magnetism and warrant extensive reviews, but the aim of this chapter is not to survey how different neutron-scattering methods are used to examine magnetic properties of different materials. Here, we concentrate on reviewing the basics of the magnetic neutron scattering, and on the recent developments in applying one of the oldest methods, the triple axis spectroscopy, that still is among the most extensively used ones. The developments discussed here are new and have not been coherently reviewed. Chapter 2 of this book reviews magnetic small-angle scattering, and modern techniques of neutron magnetic reflectometry are discussed in Chapter 3.
Freely oriented portable superconducting magnet
Schmierer, Eric N.; Prenger, F. Coyne; Hill, Dallas D.
2010-01-12
A freely oriented portable superconducting magnet is disclosed. Coolant is supplied to the superconducting magnet from a repository separate from the magnet, enabling portability of the magnet. A plurality of support assemblies structurally anchor and thermally isolate the magnet within a thermal shield. A plurality of support assemblies structurally anchor and thermally isolate the thermal shield within a vacuum vessel. The support assemblies restrain movement of the magnet resulting from energizing and cooldown, as well as from changes in orientation, enabling the magnet to be freely orientable.
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging for the
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging for the
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging
Lensless Imaging of Magnetic Nanostructures
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging
Constraining the range of Yukawa gravity interaction from S2 star orbits
Borka, D.; Jovanovi?, V. Borka; Jovanovi?, P.; Zakharov, A.F. E-mail: pjovanovic@aob.rs E-mail: zakharov@itep.ru
2013-11-01
We consider possible signatures for Yukawa gravity within the Galactic Central Parsec, based on our analysis of the S2 star orbital precession around the massive compact dark object at the Galactic Centre, and on the comparisons between the simulated orbits in Yukawa gravity and two independent sets of observations. Our simulations resulted in strong constraints on the range of Yukawa interaction ? and showed that its most probable value in the case of S2 star is around 5000 - 7000 AU. At the same time, we were not able to obtain reliable constrains on the universal constant ? of Yukawa gravity, because the current observations of S2 star indicated that it may be highly correlated with parameter ? in the range (0 < ? < 1). For ? > 2 they are not correlated. However, the same universal constant which was successfully applied to clusters of galaxies and rotation curves of spiral galaxies (? = 1/3) also gives a satisfactory agreement with the observed orbital precession of the S2 star, and in that case the most probable value for the scale parameter is ? ? 3000±1500 AU. Also, the Yukawa gravity potential induces precession of S2 star orbit in the same direction as General Relativity for ? > 0 and for ? < ?1, and in the opposite direction for ?1 < ? < 0. The future observations with advanced facilities, such as GRAVITY or/and European Extremely Large Telescope, are needed in order to verify these claims.
Astrophysical tests of modified gravity: the morphology and kinematics of dwarf galaxies
Vikram, Vinu; Cabré, Anna; Jain, Bhuvnesh; VanderPlas, J.T. E-mail: annanusca@gmail.com E-mail: jakevdp@cs.washington.edu
2013-08-01
This paper is the third in a series on tests of gravity using observations of stars and nearby dwarf galaxies. We carry out four distinct tests using published data on the kinematics and morphology of dwarf galaxies, motivated by the theoretical work of Hui et al. (2009) and Jain and Vanderplas (2011). In a wide class of gravity theories a scalar field couples to matter and provides an attractive fifth force. Due to their different self-gravity, stars and gas may respond differently to the scalar force leading to several observable deviations from standard gravity. HI gas, red giant stars and main sequence stars can be displaced relative to each other, and the stellar disk can display warps or asymmetric rotation curves aligned with external potential gradients. To distinguish the effects of modified gravity from standard astrophysical phenomena, we use a control sample of galaxies that are expected to be screened from the fifth force. In all cases we find no significant deviation from the null hypothesis of general relativity. The limits obtained from dwarf galaxies are not yet competitive with the limits from cepheids obtained in our first paper, but can be improved to probe regions of parameter space that are inaccessible using other tests. We discuss how our methodology can be applied to new radio and optical observations of nearby galaxies.
Penarrubia, Jorge; Walker, Matthew G.
2012-11-20
We introduce the Minimum Entropy Method, a simple statistical technique for constraining the Milky Way gravitational potential and simultaneously testing different gravity theories directly from 6D phase-space surveys and without adopting dynamical models. We demonstrate that orbital energy distributions that are separable (i.e., independent of position) have an associated entropy that increases under wrong assumptions about the gravitational potential and/or gravity theory. Of known objects, 'cold' tidal streams from low-mass progenitors follow orbital distributions that most nearly satisfy the condition of separability. Although the orbits of tidally stripped stars are perturbed by the progenitor's self-gravity, systematic variations of the energy distribution can be quantified in terms of the cross-entropy of individual tails, giving further sensitivity to theoretical biases in the host potential. The feasibility of using the Minimum Entropy Method to test a wide range of gravity theories is illustrated by evolving restricted N-body models in a Newtonian potential and examining the changes in entropy introduced by Dirac, MONDian, and f(R) gravity modifications.
Device for detecting the specific gravity of a liquid. [Patent application
Derouin, C.R.; Kerwin, W.J.; McCormick, J.B.; Bobbett, R.E.
1980-11-18
A device for detecting the specific gravity of a liquid and a device for detecting the state of charge of a liquid phase electrolyte battery are described. In one embodiment of the present invention, a change in the critical angle of total internal reflection is utilized to determine the index of refraction of the liquid to be measured. It is shown that the index of refraction of the liquid is a function of the specific gravity of the liquid. In applications for measuring the state of charge of a battery, the specific gravity is proportional to the state of charge of the battery. A change in intensity of rays intersecting an interface surface indicates the critical angle which is a direct indication of the specific gravity of the liquid and the state of charge of a battery. In another embodiment, a light beam is projected through a transparent medium and then through a portion of the liquid to be measured. A change in refraction due to a change in the index of refraction of the liquid produces a deflection of the beam which is measured by a detector. The magnitude of deflection of the beam is directly proportional to the specific gravity of the liquid and the state of charge of a battery.
Christian, Joshua M.; Ho, Clifford Kuofei
2010-04-01
Understanding the effects of gravity and wind loads on concentrating solar power (CSP) collectors is critical for performance calculations and developing more accurate alignment procedures and techniques. This paper presents a rigorous finite-element model of a parabolic trough collector that is used to determine the impact of gravity loads on bending and displacements of the mirror facets and support structure. The geometry of the LUZ LS-2 parabolic trough collector was modeled using SolidWorks, and gravity-induced loading and displacements were simulated in SolidWorks Simulation. The model of the trough collector was evaluated in two positions: the 90{sup o} position (mirrors facing upward) and the 0{sup o} position (mirrors facing horizontally). The slope errors of the mirror facet reflective surfaces were found by evaluating simulated angular displacements of node-connected segments along the mirror surface. The ideal (undeformed) shape of the mirror was compared to the shape of the deformed mirror after gravity loading. Also, slope errors were obtained by comparing the deformed shapes between the 90{sup o} and 0{sup o} positions. The slope errors resulting from comparison between the deformed vs. undeformed shape were as high as {approx}2 mrad, depending on the location of the mirror facet on the collector. The slope errors resulting from a change in orientation of the trough from the 90{sup o} position to the 0{sup o} position with gravity loading were as high as {approx}3 mrad, depending on the location of the facet.
Magnetic reconnection launcher
Cowan, Maynard
1989-01-01
An electromagnetic launcher includes a plurality of electrical stages which are energized sequentially in synchrony with the passage of a projectile. Each stage of the launcher includes two or more coils which are arranged coaxially on either closed-loop or straight lines to form gaps between their ends. The projectile has an electrically conductive gap-portion that passes through all the gaps of all the stages in a direction transverse to the axes of the coils. The coils receive an electric current, store magnetic energy, and convert a significant portion of the stored magnetic energy into kinetic energy of the projectile by magnetic reconnection as the gap portion of the projectile moves through the gap. The magnetic polarity of the opposing coils is in the same direction, e.g. N-S-N-S. A gap portion of the projectile may be made from aluminum and is propelled by the reconnection of magnetic flux stored in the coils which causes accelerating forces to act upon the projectile at both the rear vertical surface of the projectile and at the horizontal surfaces of the projectile near its rear. The gap portion of the projectile may be flat, rectangular and longer than the length of the opposing coils and fit loosely within the gap between the opposing coils.
Barclay, J.A.; Steyert, W.A.
1981-01-27
An apparatus and method for refrigeration are disclosed which provides efficient refrigeration over temperature ranges in excess of 20/sup 0/C and which requires no maintenance and is, therefore, usable on an unmanned satellite. The apparatus comprises a superconducting magnet which may be solenoidal. A piston comprising a substance such as a rare earth substance which is maintained near its Curie temperature reciprocates through the bore of the solenoidal magnet. A magnetic drive rod is connected to the piston and appropriate heat sinks are connected thereto. The piston is driven by a suitable mechanical drive such as an electric motor and cam. In practicing the invention, the body of the piston is magnetized and demagnetized as it moves through the magnetic field of the solenoid to approximate any of the following cycles or a condition thereof as well as, potentially, other cycles: Brayton, Carnot, Ericsson, and Stirling. Advantages of the present invention include: that refrigeration can be accomplished over at least a 20/sup 0/C scale at superconducting temperatures as well as at more conventional temperatures; very high efficiency, high reliability, and small size. (LCL)
Thermodynamics of asymptotically flat charged black holes in third order Lovelock gravity
Dehghani, M.H.; Shamirzaie, M.
2005-12-15
We present a new class of asymptotically flat charge static solutions in third order Lovelock gravity. These solutions present black hole solutions with two inner and outer event horizons, extreme black holes, or naked singularities provided the parameters of the solutions are chosen suitable. We find that the uncharged asymptotically flat solutions can present black holes with two inner and outer horizons. This kind of solution does not exist in Einstein or Gauss-Bonnet gravity, and it is a special effect in third order Lovelock gravity. We compute temperature, entropy, charge, electric potential, and mass of the black hole solutions, and find that these quantities satisfy the first law of thermodynamics. We also perform a stability analysis by computing the determinant of the Hessian matrix of the mass with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that there exists only an intermediate stable phase.
An experimental study of pool boiling heat transfer in reduced gravity
Shatto, D.P.; Renzi, K.I.; Peterson, G.P.; Morris, T.K.; Aaron, J.W.
1996-12-31
Experiments were performed in which pool boiling of pure water at reduced pressures was observed for behavior of the critical heatflux (CHF) and nucleate boiling heat transfer coefficients in a reduced gravitational environment. The experiments took place while alternating between microgravity and g/g{sub o} = 1.8 during parabolic flights aboard the NASA 930 (KC-135A). Heat transfer data were also obtained at Martian gravity levels (g/g{sub o} = 1/3). Parts of the test chamber were constructed of transparent materials to allow viewing and recording of the various boiling regimes encountered during the experiments. Results indicate that the onset of nucleate boiling occurred at lower heat fluxes in reduced gravity, resulting in higher two-phase heat transfer coefficients for g/g{sub o} < 1 than for g/g{sub o} = 1.8. In addition, the results indicate a significant reduction in the critical heat flux under reduced gravity conditions.
Magnetic nanoparticle temperature estimation
Weaver, John B.; Rauwerdink, Adam M.; Hansen, Eric W.
2009-05-15
The authors present a method of measuring the temperature of magnetic nanoparticles that can be adapted to provide in vivo temperature maps. Many of the minimally invasive therapies that promise to reduce health care costs and improve patient outcomes heat tissue to very specific temperatures to be effective. Measurements are required because physiological cooling, primarily blood flow, makes the temperature difficult to predict a priori. The ratio of the fifth and third harmonics of the magnetization generated by magnetic nanoparticles in a sinusoidal field is used to generate a calibration curve and to subsequently estimate the temperature. The calibration curve is obtained by varying the amplitude of the sinusoidal field. The temperature can then be estimated from any subsequent measurement of the ratio. The accuracy was 0.3 deg. K between 20 and 50 deg. C using the current apparatus and half-second measurements. The method is independent of nanoparticle concentration and nanoparticle size distribution.
Aized, D.; Schwall, R.E.
1999-06-22
A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil. 15 figs.
Aized, Dawood (Marlboro, MA); Schwall, Robert E. (Northborough, MA)
1999-06-22
A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil.
Aized, Dawood (Marlboro, MA); Schwall, Robert E. (Northborough, MA)
1996-06-11
A superconducting magnetic coil includes a plurality of sections positioned axially along the longitudinal axis of the coil, each section being formed of an anisotropic high temperature superconductor material wound about a longitudinal axis of the coil and having an associated critical current value that is dependent on the orientation of the magnetic field of the coil. The cross section of the superconductor, or the type of superconductor material, at sections along the axial and radial axes of the coil are changed to provide an increased critical current at those regions where the magnetic field is oriented more perpendicularly to the conductor plane, to thereby increase the critical current at these regions and to maintain an overall higher critical current of the coil.
Inflation in Kaluza-Klein cosmology. 1; Transformation to fourth-order gravity
Schmidt, H.J. )
1990-12-20
This paper reports on the higher- dimensional Einstein equation with {Gamma}-term shown to be comformally equivalent to the four-dimensional field equation of scale-invariant fourth-order gravity. This holds for a general warped product between space-time and internal space of arbitrary dimension m which turns out to be an Einstein space. (The limit m {yields} {infinity} makes sense ) Thus, the results concerning the attractor property of the power- law inflationary solution derived for fourth-order gravity hold for the Kaluza-Klein model, too.
Quasispherical gravitational collapse in 5D Einstein-Gauss-Bonnet gravity
Ghosh, Sushant G.; Jhingan, S.
2010-07-15
We obtain a general five-dimensional quasispherical collapsing solutions of irrotational dust in Einstein gravity with the Gauss-Bonnet combination of quadratic curvature terms. These solutions are a generalization, to Einstein-Gauss-Bonnet gravity, of the five-dimensional quasispherical Szkeres like collapsing solutions in general relativity. It is found that the collapse proceeds in the same way as in the analogous spherical collapse, i.e., there exists regular initial data such that the collapse proceed to form naked singularities violating cosmic censorship conjecture. The effect of Gauss-Bonnet quadratic curvature terms on the formation and locations of the apparent horizon is deduced.
,"Domestic Crude Oil First Purchase Prices by API Gravity"
U.S. Energy Information Administration (EIA) Indexed Site
API Gravity" ,"Click worksheet name or tab at bottom for data" ,"Worksheet Name","Description","# Of Series","Frequency","Latest Data for" ,"Data 1","Domestic Crude Oil First Purchase Prices by API Gravity",6,"Monthly","12/2015","10/15/1993" ,"Release Date:","3/1/2016" ,"Next Release Date:","4/1/2016" ,"Excel File
Toward the AdS/CFT gravity dual for high energy collisions. I. Falling into
Office of Scientific and Technical Information (OSTI)
the AdS space (Journal Article) | SciTech Connect I. Falling into the AdS space Citation Details In-Document Search Title: Toward the AdS/CFT gravity dual for high energy collisions. I. Falling into the AdS space In the context of the AdS/CFT correspondence we discuss the gravity dual of a high energy collision in a strongly coupled N=4 SYM gauge theory. We suggest a setting in which two colliding objects are made of nondynamical heavy quarks and antiquarks, which allows one to treat the
Zhao, Gong-Bo
2014-04-01
Based on a suite of N-body simulations of the Hu-Sawicki model of f(R) gravity with different sets of model and cosmological parameters, we develop a new fitting formula with a numeric code, MGHalofit, to calculate the nonlinear matter power spectrum P(k) for the Hu-Sawicki model. We compare the MGHalofit predictions at various redshifts (z ? 1) to the f(R) simulations and find that the relative error of the MGHalofit fitting formula of P(k) is no larger than 6% at k ? 1 h Mpc{sup –1} and 12% at k in (1, 10] h Mpc{sup –1}, respectively. Based on a sensitivity study of an ongoing and a future spectroscopic survey, we estimate the detectability of a signal of modified gravity described by the Hu-Sawicki model using the power spectrum up to quasi-nonlinear scales.
Powell, J.; Reich, M.; Danby, G.
1997-07-22
A magnetic imager includes a generator for practicing a method of applying a background magnetic field over a concealed object, with the object being effective to locally perturb the background field. The imager also includes a sensor for measuring perturbations of the background field to detect the object. In one embodiment, the background field is applied quasi-statically. And, the magnitude or rate of change of the perturbations may be measured for determining location, size, and/or condition of the object. 25 figs.
Powell, James (Shoreham, NY); Reich, Morris (Kew Garden Hills, NY); Danby, Gordon (Wading River, NY)
1997-07-22
A magnetic imager 10 includes a generator 18 for practicing a method of applying a background magnetic field over a concealed object, with the object being effective to locally perturb the background field. The imager 10 also includes a sensor 20 for measuring perturbations of the background field to detect the object. In one embodiment, the background field is applied quasi-statically. And, the magnitude or rate of change of the perturbations may be measured for determining location, size, and/or condition of the object.
Disorder-Induced Microscopic Magnetic Memory
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Disorder-Induced Microscopic Magnetic Memory Disorder-Induced Microscopic Magnetic Memory Print Wednesday, 26 October 2005 00:00 The magnetic-recording industry deliberately...
Category:Magnetic Techniques | Open Energy Information
Magnetic Techniques Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Geothermalpower.jpg Looking for the Magnetic Techniques page? For detailed information on Magnetic...
Magnet Motor Corp | Open Energy Information
Magnet Motor Corp Jump to: navigation, search Name: Magnet Motor Corp. Place: Starnberg, Germany Zip: 82319 Sector: Vehicles Product: Magnet motor Corp has been developing and...
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors
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Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print Wednesday, 29 November 2006 00:00 The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted
Magnetic Filtration Process, Magnetic Filtering Material, and Method of
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Forming Magnetic Filtering Material - Energy Innovation Portal Industrial Technologies Industrial Technologies Find More Like This Return to Search Magnetic Filtration Process, Magnetic Filtering Material, and Method of Forming Magnetic Filtering Material Oak Ridge National Laboratory Contact ORNL About This Technology Technology Marketing SummaryORNL researchers developed a new method for filtering materials and managing wastewater. This invention offers an integrated, intensified process
Kirol, Lance D. (Shelly, ID)
1988-01-01
A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation.
Kirol, L.D.
1987-02-11
A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation. 5 figs.
Jackson, Jasper A. (Los Alamos, NM); Cooper, Richard K. (Los Alamos, NM)
1982-01-01
Means for producing a region of homogeneous magnetic field remote from the source of the field, wherein two equal field sources are arranged axially so their fields oppose, producing a region near the plane perpendicular to the axis midway between the sources where the radial component of the field goes through a maximum. Near the maximum, the field is homogeneous over prescribed regions.
Large Magnetization at Carbon Surfaces
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Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure...
Magnetic Materials | Advanced Photon Source
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Materials Internal Magnetic Materials The Magnetic Material Group (MMG) is part of the X-ray Science Division (XSD) at the Advanced Photon Source (APS). Our research focuses on the...
Magnet Cooldown and Warmup Model
Energy Science and Technology Software Center (OSTI)
1995-07-11
This program evaluates cooldown/warmup performance of an SSC magnet or magnet strings, But can be applied to any other iron coldmass which is cooled or warmed by helium.
Magnetic refrigeration apparatus and method
Barclay, J.A.; Overton, W.C. Jr.; Stewart, W.F.
The disclosure relates to refrigeration through magnetizing and demagnitizing a body by rotating it within a magnetic field. Internal and external heat exchange fluids and in one embodiment, a regenerator, are used.
Magnetic refrigeration apparatus and method
Barclay, John A.; Overton, Jr., William C.; Stewart, Walter F.
1984-01-01
The disclosure relates to refrigeration through magnetizing and demagnitizing a body by rotating it within a magnetic field. Internal and external heat exchange fluids and in one embodiment, a regenerator, are used.
Magnetic reconnection launcher
Cowan, M.
1987-04-06
An electromagnetic launcher includes a plurality of electrical stages which are energized sequentially in the launcher with the passage of a projectiles. Each stage of the launcher includes two or more coils which are arranged coaxially on either closed-loop or straight lines to form gaps between their ends. The projectile has an electrically conductive gap-portion that passes through all the gaps of all the stages in a direction transverse to the axes of the coils. The coils receive an electric current, store magnetic energy, and convert a significant portion of the stored magnetic energy into kinetic energy of the projectile moves through the gap. The magnetic polarity of the opposing coils is in the same direction, e.g. N-S-N-S. A gap portion of the projectile may be made from aluminum and is propelled by the reconnection of magnetic flux stored in the coils which causes accelerating forces to act upon the projectile and at the horizontal surfaces of the projectile near its rear. The gap portion of the projectile may be flat, rectangular and longer than the length of the opposing coils. The gap portion of the projectile permits substantially unrestricted distribution of the induced currents so that current densities are only high where the useful magnetic force is high. This allows designs which permit ohmic oblation from the rear surfaces of the gap portion of the projectile allowing much high velocities to be achieved. An electric power apparatus controls the electric power supplied to the opposing coils until the gap portion of the projectile substantially occupies the gap between the coils, at which time the coils are supplied with peak current quickly. 8 figs.
Evolution of twisted magnetic fields
Zweibel, E.G.; Boozer, A.H.
1985-02-01
The magnetic field of the solar corona evolves quasistatically in response to slowly changing photospheric boundary conditions. The magnetic topology is preserved by the low resistivity of the solar atmosphere. We show that a magnetic flux coordinate system simplifies the problem of calculating field evolution with invariant topology. As an example, we calculate the equilibrium of a thin magnetic flux tube with small twist per unit length.
Carbon Joins the Magnetic Club
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Press Release 29 May 2007 Carbon Joins the Magnetic Club summary written by Brad Plummer, SLAC Communication Office The exclusive club of magnetic elements officially has a new member-carbon. Using a proton beam and advanced x-ray techniques, SLAC researchers in collaboration with colleagues from LBNL and the University of Leipzig in Germany have finally put to rest doubts about carbon's ability to be made magnetic. "In the past, some groups thought they had discovered magnetic
Ames Lab 101: Magnetic Refrigeration
Pecharsky, Vitalij
2013-03-01
Vitalij Pecharsky, distinguished professor of materials science and engineering, discusses his research in magnetic refrigeration at Ames Lab.
Ames Lab 101: Magnetic Refrigeration
Pecharsky, Vitalij
2011-01-01
Vitalij Pecharsky, distinguished professor of materials science and engineering, discusses his research in magnetic refrigeration at Ames Lab.
Low-temperature magnetic refrigerator
Barclay, J.A.
1983-05-26
The invention relates to magnetic refrigeration and more particularly to low temperature refrigeration between about 4 and about 20 K, with an apparatus and method utilizing a belt of magnetic material passed in and out of a magnetic field with heat exchangers within and outside the field operably disposed to accomplish refrigeration.
Low-temperature magnetic refrigerator
Barclay, John A. (Los Alamos, NM)
1985-01-01
The disclosure is directed to a low temperature 4 to 20 K. refrigeration apparatus and method utilizing a ring of magnetic material moving through a magnetic field. Heat exchange is accomplished in and out of the magnetic field to appropriately utilize the device to execute Carnot and Stirling cycles.
Low field magnetic resonance imaging
Pines, Alexander (Berkeley, CA); Sakellariou, Dimitrios (Billancourt, FR); Meriles, Carlos A. (Fort Lee, NJ); Trabesinger, Andreas H. (London, GB)
2010-07-13
A method and system of magnetic resonance imaging does not need a large homogenous field to truncate a gradient field. Spatial information is encoded into the spin magnetization by allowing the magnetization to evolve in a non-truncated gradient field and inducing a set of 180 degree rotations prior to signal acquisition.
Entirely passive heat-pipe apparatus capable of operating against gravity
Koenig, D.R.
1981-02-11
The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.
Effective matter cosmologies of massive gravity I: non-physical fluids
Y?lmaz, Nejat Tevfik
2014-08-01
For the massive gravity, after decoupling from the metric equation we find a broad class of solutions of the Stückelberg sector by solving the background metric in the presence of a diagonal physical metric. We then construct the dynamics of the corresponding FLRW cosmologies which inherit effective matter contribution through the decoupling solution mechanism of the scalar sector.
Existence of global weak solution for a reduced gravity two and a half layer model
Guo, Zhenhua Li, Zilai Yao, Lei
2013-12-15
We investigate the existence of global weak solution to a reduced gravity two and a half layer model in one-dimensional bounded spatial domain or periodic domain. Also, we show that any possible vacuum state has to vanish within finite time, then the weak solution becomes a unique strong one.
A scaling analysis of thermoacoustic convection in a zero-gravity environment
Krane, R.J.; Parang, M.
1982-01-01
This paper presents a scaling analysis of a one-dimensional thermoacoustic convection heat transfer process in a zero-gravity environment. The relative importance of the terms in the governing equations is discussed for different time scales without attempting to solve the equations. The scaling analysis suggests certain generalizations that can be made in this class of heat transfer problems.
Spherical collapse in Galileon gravity: fifth force solutions, halo mass function and halo bias
Barreira, Alexandre; Li, Baojiu; Baugh, Carlton M.; Pascoli, Silvia E-mail: liqb@mail.ihep.ac.cn E-mail: silvia.pascoli@durham.ac.uk
2013-11-01
We study spherical collapse in the Quartic and Quintic Covariant Galileon gravity models within the framework of the excursion set formalism. We derive the nonlinear spherically symmetric equations in the quasi-static and weak-field limits, focusing on model parameters that fit current CMB, SNIa and BAO data. We demonstrate that the equations of the Quintic model do not admit physical solutions of the fifth force in high density regions, which prevents the study of structure formation in this model. For the Quartic model, we show that the effective gravitational strength deviates from the standard value at late times (z?<1), becoming larger if the density is low, but smaller if the density is high. This shows that the Vainshtein mechanism at high densities is not enough to screen all of the modifications of gravity. This makes halos that collapse at z?<1 feel an overall weaker gravity, which suppresses halo formation. However, the matter density in the Quartic model is higher than in standard ?CDM, which boosts structure formation and dominates over the effect of the weaker gravity. In the Quartic model there is a significant overabundance of high-mass halos relative to ?CDM. Dark matter halos are also less biased than in ?CDM, with the difference increasing appreciably with halo mass. However, our results suggest that the bias may not be small enough to fully reconcile the predicted matter power spectrum with LRG clustering data.
Regenerator for Magnetic Refrigerants - Energy Innovation Portal
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Magnetic refrigeration is being investigated as an alternative to conventional gas ... materials may thus have improved properties for magnetic refrigeration. ...
Iterative reconstruction of magnetic induction using Lorentz...
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Iterative reconstruction of magnetic induction using Lorentz transmission electron tomography Title Iterative reconstruction of magnetic induction using Lorentz transmission...
Method of making permanent magnets
McCallum, R.W.; Dennis, K.W.; Lograsso, B.K.; Anderson, I.E.
1993-09-07
A method for making an isotropic permanent magnet comprises atomizing a melt of a rare earth-transition metal alloy (e.g., an Nd--Fe--B alloy enriched in Nd and B) under conditions to produce protectively coated, rapidly solidified, generally spherical alloy particles. Wherein a majority of the particles are produced/size classified within a given size fraction (e.g., 5 to 40 microns diameter) exhibiting optimum as-atomized magnetic properties and subjecting the particles to concurrent elevated temperature and elevated isotropic pressure for a time effective to yield a densified, magnetically isotropic magnet compact having enhanced magnetic properties and mechanical properties. 13 figures.
Method of making permanent magnets
McCallum, R. William (Ames, IA); Dennis, Kevin W. (Ames, IA); Lograsso, Barbara K. (Ames, IA); Anderson, Iver E. (Ames, IA)
1993-09-07
A method for making an isotropic permanent magnet comprises atomizing a melt of a rare earth-transition metal alloy (e.g., an Nd--Fe--B alloy enriched in Nd and B) under conditions to produce protectively coated, rapidly solidified, generally spherical alloy particles wherein a majority of the particles are produced/size classified within a given size fraction (e.g., 5 to 40 microns diameter) exhibiting optimum as-atomized magnetic properties and subjecting the particles to concurrent elevated temperature and elevated isotropic pressure for a time effective to yield a densified, magnetically isotropic magnet compact having enhanced magnetic properties and mechanical properties.
Large Magnetization at Carbon Surfaces
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Large Magnetization at Carbon Surfaces Large Magnetization at Carbon Surfaces Print Wednesday, 31 August 2011 00:00 From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the
Inductrack magnet configuration
Post, Richard Freeman
2003-10-14
A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track of windings is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.
Inductrack magnet configuration
Post, Richard Freeman
2003-12-16
A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track of windings is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.
Fast superconducting magnetic field switch
Goren, Y.; Mahale, N.K.
1996-08-06
The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. 6 figs.
Fast superconducting magnetic field switch
Goren, Yehuda (Mountain View, CA); Mahale, Narayan K. (The Woodlands, TX)
1996-01-01
The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles.
Magnetic hydrogel with high coercivity
Sözeri, H.; Alvero?lu, E.; Kurtan, U.; ?enel, M.; Baykal, A.
2013-08-01
Highlights: • Polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles have been prepared. • Magnetization measurements reveal that hydrogels have hard magnetic properties with high coercivity. • Magnetic nanoparticles makes the gel more homogeneous and do not diffuse out of the gel during water intake. • These gels are useful in applications as wastewater treatment once gels are magnetized before its usage. - Abstract: This study investigates the synthesis and characterization of polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles. Structural, electrical, and magnetic characterization of the gels have been performed with X-ray powder diffractometry, scanning electron microscopy, DC conductivity, magnetization and fluorescence spectroscopy techniques. The preparation and characterization of polyacrylamide (PAAm) hydrogels that contain 5 and 10 mg BaFe{sub 12}O{sub 19} (16 and 21 nm diameter) nanoparticles are described herein. It is seen from the fluorescence spectra that, nanoparticles surrounded to pyranine molecules so that some of pyranine molecules could not bound to the polymer strands. Electrical measurements show that presence of nanoparticles make the gel more homogeneous. Magnetization measurements reveal that hydrogels have hard magnetic properties with quite high coercivity of 4.2 kOe, which does not change with swelling. This feature makes these gels useful in applications as wastewater treatment if they are magnetized before use.
Jackson, J.A.; Cooper, R.K.
1980-10-10
The patent consists of means for producing a region of homogeneous magnetic field remote from the source of the field, wherein two equal field sources are arranged axially so their fields oppose, producing a region near the plane perpendicular to the axis midway between the sources where the radial correspondent of the field goes through a maximum. Near the maximum, the field is homogeneous over prescribed regions.
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors
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Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host
Apparatus and method for continuous separation of magnetic particles from non-magnetic fluids
Oder, Robin R. (Export, PA); Jamison, Russell E. (Burrell, PA)
2011-11-08
An apparatus and method for continuous separation of magnetic particles from non-magnetic fluids including particular rods, magnetic fields and flow arrangements.
Continuous magnetic separator and process
Oder, Robin R. (Export, PA); Jamison, Russell E. (Lower Burrell, PA)
2008-04-22
A continuous magnetic separator and process for separating a slurry comprising magnetic particles into a clarified stream and a thickened stream. The separator has a container with a slurry inlet, an overflow outlet for the discharge of the clarified slurry stream, and an underflow outlet for the discharge of a thickened slurry stream. Magnetic particles in the slurry are attracted to, and slide down, magnetic rods within the container. The slurry is thus separated into magnetic concentrate and clarified slurry. Flow control means can be used to control the ratio of the rate of magnetic concentrate to the rate of clarified slurry. Feed control means can be used to control the rate of slurry feed to the slurry inlet.
Thin film superconductor magnetic bearings
Weinberger, Bernard R. (Avon, CT)
1995-12-26
A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.
Non-perturbative and self-consistent models of neutron stars in R-squared gravity
Yazadjiev, Stoytcho S.; Doneva, Daniela D.; Kokkotas, Kostas D.; Staykov, Kalin V. E-mail: daniela.doneva@uni-tuebingen.de E-mail: kalin.v.staikov@gmail.com
2014-06-01
In the present paper we investigate non-perturbatively and self-consistently the structure of neutron stars in R-squared gravity by simultaneously solving the interior and exterior problem. The mass-radius relations are obtained for several equations of state and for wide range of the R-squared gravity parameter a. Even though the deviation from general relativity for nonzero values of a can be large, they are still comparable with the variations due to different modern realistic equations of state. That is why the current observations of the neutron star masses and radii alone can not put constraints on the value of the parameter a. We also compare our results with those obtained within the perturbative method and we discuss the differences between them.
Cosmological bounces in spatially flat FRW spacetimes in metric f(R) gravity
Paul, Niladri; Chakrabarty, Saikat Nil; Bhattacharya, Kaushik E-mail: snilch@iitk.ac.in
2014-10-01
The present work analyzes the various conditions in which there can be a bouncing universe solution in f(R) gravity. In the article an interesting method, to analyze the bouncing FRW solutions in a spatially flat universe using f(R) gravity models using an effective Einstein frame description of the process, is presented. The analysis shows that a cosmological bounce in the f(R) theory need not be described by an equivalent bounce in the Einstein frame description of the process where actually there may be no bounce at all. Nevertheless the Einstein frame description of the bouncing phenomena turns out to be immensely important as the dynamics of the bounce becomes amenable to logic based on general relativistic intuition. The theory of scalar cosmological perturbations in the bouncing universe models in f(R) theories has also been worked out in the Einstein frame.
The Role of Gravity Waves in the Formation and Organization of Clouds during TWPICE
Reeder, Michael J.; Lane, Todd P.; Hankinson, Mai Chi Nguyen
2013-09-27
All convective clouds emit gravity waves. While it is certain that convectively-generated waves play important parts in determining the climate, their precise roles remain uncertain and their effects are not (generally) represented in climate models. The work described here focuses mostly on observations and modeling of convectively-generated gravity waves, using the intensive observations from the DoE-sponsored Tropical Warm Pool International Cloud Experiment (TWP-ICE), which took place in Darwin, from 17 January to 13 February 2006. Among other things, the research has implications the part played by convectively-generated gravity waves in the formation of cirrus, in the initiation and organization of further convection, and in the subgrid-scale momentum transport and associated large-scale stresses imposed on the troposphere and stratosphere. The analysis shows two groups of inertia-gravity waves are detected: group L in the middle stratosphere during the suppressed monsoon period, and group S in the lower stratosphere during the monsoon break period. Waves belonging to group L propagate to the south-east with a mean intrinsic period of 35 h, and have vertical and horizontal wavelengths of about 5-6 km and 3000-6000 km, respectively. Ray tracing calculations indicate that these waves originate from a deep convective region near Indonesia. Waves belonging to group S propagate to the south-south-east with an intrinsic period, vertical wavelength and horizontal wavelength of about 45 h, 2 km and 2000-4000 km, respectively. These waves are shown to be associated with shallow convection in the oceanic area within about 1000 km of Darwin. The intrinsic periods of high-frequency waves are estimated to be between 20-40 minutes. The high-frequency wave activity in the stratosphere, defined by mass-weighted variance of the vertical motion of the sonde, has a maximum following the afternoon local convection indicating that these waves are generated by local convection. The wave activity is strongest in the lower stratosphere below 22 km and, during the suppressed monsoon period, is modulated with a 3-4-day period. The concentration of the wave activity in the lower stratosphere is consistent with the properties of the environment in which these waves propagate, whereas its 3-4-day modulation is explained by the variation of the convection activity in the TWP-ICE domain. At low rainfall intensity the wave activity increases as rainfall intensity increases. At high values of rainfall intensity, however, the wave activity associated with deep convective clouds is independent of the rainfall intensity. The convection and gravity waves observed during TWP-ICE are simulated with the Weather Research and Forecasting (WRF) Model. These simulations are compared with radiosonde observations described above and are used to determine some of the properties of convectively generated gravity waves. The gravity waves appear to be well simulated by the model. The model is used to explore the relationships between the convection, the gravity waves and cirrus.
The response of plasma density to breaking inertial gravity wave in the lower regions of ionosphere
Tang, Wenbo Mahalov, Alex
2014-04-15
We present a three-dimensional numerical study for the E and lower F region ionosphere coupled with the neutral atmosphere dynamics. This model is developed based on a previous ionospheric model that examines the transport patterns of plasma density given a prescribed neutral atmospheric flow. Inclusion of neutral dynamics in the model allows us to examine the charge-neutral interactions over the full evolution cycle of an inertial gravity wave when the background flow spins up from rest, saturates and eventually breaks. Using Lagrangian analyses, we show the mixing patterns of the ionospheric responses and the formation of ionospheric layers. The corresponding plasma density in this flow develops complex wave structures and small-scale patches during the gravity wave breaking event.
Patterns of gravity induced aggregate migration during casting of fluid concretes
Spangenberg, J. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark)] [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Roussel, N., E-mail: Nicolas.roussel@lcpc.fr [Universite Paris Est, Laboratoire Central des Ponts et Chaussees (LCPC) (France); Hattel, J.H. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark)] [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Sarmiento, E.V.; Zirgulis, G. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway)] [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Geiker, M.R. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway) [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Department of Civil Engineering, Technical University of Denmark (DTU) (Denmark)
2012-12-15
In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.
Einstein–Cartan gravity, Asymptotic Safety, and the running Immirzi parameter
Daum, J.-E.; Reuter, M.
2013-07-15
In this paper we analyze the functional renormalization group flow of quantum gravity on the Einstein–Cartan theory space. The latter consists of all action functionals depending on the spin connection and the vielbein field (co-frame) which are invariant under both spacetime diffeomorphisms and local frame rotations. In the first part of the paper we develop a general methodology and corresponding calculational tools which can be used to analyze the flow equation for the pertinent effective average action for any truncation of this theory space. In the second part we apply it to a specific three-dimensional truncated theory space which is parametrized by Newton’s constant, the cosmological constant, and the Immirzi parameter. A comprehensive analysis of their scale dependences is performed, and the possibility of defining an asymptotically safe theory on this hitherto unexplored theory space is investigated. In principle Asymptotic Safety of metric gravity (at least at the level of the effective average action) is neither necessary nor sufficient for Asymptotic Safety on the Einstein–Cartan theory space which might accommodate different “universality classes” of microscopic quantum gravity theories. Nevertheless, we do find evidence for the existence of at least one non-Gaussian renormalization group fixed point which seems suitable for the Asymptotic Safety construction in a setting where the spin connection and the vielbein are the fundamental field variables. -- Highlights: •A functional RG equation for a first order formulation of gravity is constructed. •The theory space constituted by tetrad and spin connection variables is explored. •The RG equation is solved in a 3 dimensional truncation of theory space. •The flow of Newton’s constant, the cosmological constant and the Immirzi parameter is analyzed. •Evidence for the nonperturbative renormalizability of the theory is found.
Astrophysical tests of modified gravity: Constraints from distance indicators in the nearby universe
Jain, Bhuvnesh; Vikram, Vinu; Sakstein, Jeremy
2013-12-10
We use distance measurements in the nearby universe to carry out new tests of gravity, surpassing other astrophysical tests by over two orders of magnitude for chameleon theories. The three nearby distance indicators—cepheids, tip of the red giant branch (TRGB) stars, and water masers—operate in gravitational fields of widely different strengths. This enables tests of scalar-tensor gravity theories because they are screened from enhanced forces to different extents. Inferred distances from cepheids and TRGB stars are altered (in opposite directions) over a range of chameleon gravity theory parameters well below the sensitivity of cosmological probes. Using published data, we have compared cepheid and TRGB distances in a sample of unscreened dwarf galaxies within 10 Mpc. We use a comparable set of screened galaxies as a control sample. We find no evidence for the order unity force enhancements expected in these theories. Using a two-parameter description of the models (the coupling strength and background field value), we obtain constraints on both the chameleon and symmetron screening scenarios. In particular we show that f(R) models with background field values f {sub R0} above 5 × 10{sup –7} are ruled out at the 95% confidence level. We also compare TRGB and maser distances to the galaxy NGC 4258 as a second test for larger field values. While there are several approximations and caveats in our study, our analysis demonstrates the power of gravity tests in the local universe. We discuss the prospects for additional improved tests with future observations.
The coupling to matter in massive, bi- and multi-gravity
Noller, Johannes; Melville, Scott E-mail: scott.melville@queens.ox.ac.uk
2015-01-01
In this paper we construct a family of ways in which matter can couple to one or more 'metrics'/spin-2 fields in the vielbein formulation. We do so subject to requiring the weak equivalence principle and the absence of ghosts from pure spin-2 interactions generated by the matter action. Results are presented for Massive, Bi- and Multi-Gravity theories and we give explicit expressions for the effective matter metric in all of these cases.
Tsunami and acoustic-gravity waves in water of constant depth
Hendin, Gali; Stiassnie, Michael
2013-08-15
A study of wave radiation by a rather general bottom displacement, in a compressible ocean of otherwise constant depth, is carried out within the framework of a three-dimensional linear theory. Simple analytic expressions for the flow field, at large distance from the disturbance, are derived. Realistic numerical examples indicate that the Acoustic-Gravity waves, which significantly precede the Tsunami, are expected to leave a measurable signature on bottom-pressure records that should be considered for early detection of Tsunami.
Toward the AdS/CFT gravity dual for high energy collisions. III.
Office of Scientific and Technical Information (OSTI)
Gravitationally collapsing shell and quasiequilibrium (Journal Article) | SciTech Connect III. Gravitationally collapsing shell and quasiequilibrium Citation Details In-Document Search Title: Toward the AdS/CFT gravity dual for high energy collisions. III. Gravitationally collapsing shell and quasiequilibrium The equilibration of matter and onset of hydrodynamics can be understood in the AdS/CFT context as a gravitational collapse process, in which 'collision debris' create a horizon. In
BNL Direct Wind Superconducting Magnets
Parker, B.; Anerella, M.; Escallier, J.; Ghosh, A.; Jain, A.; Marone, A.; Muratore, A.; Wanderer, P.
2011-09-12
BNL developed Direct Wind magnet technology is used to create a variety of complex multi-functional multi-layer superconducting coil structures without the need for creating custom production tooling and fixturing for each new project. Our Direct Wind process naturally integrates prestress into the coil structure so external coil collars and yokes are not needed; the final coil package transverse size can then be very compact. Direct Wind magnets are produced with very good field quality via corrections applied during the course of coil winding. The HERA-II and BEPC-II Interaction Region (IR) magnet, J-PARC corrector and Alpha antihydrogen magnetic trap magnets and our BTeV corrector magnet design are discussed here along with a full length ILC IR prototype magnet presently in production and the coils that were wound for an ATF2 upgrade at KEK. A new IR septum magnet design concept for a 6.2 T combined-function IR magnet for eRHIC, a future RHIC upgrade, is introduced here.
Ground Magnetics | Open Energy Information
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Large Magnetization at Carbon Surfaces
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
sensors, and data processing. Fortunately, additional research has proven that etching carbon with sulfuric acid can also make the carbon magnetic, opening the door for...
Magnetic compression laser driving circuit
Ball, D.G.; Birx, D.; Cook, E.G.
1993-01-05
A magnetic compression laser driving circuit is disclosed. The magnetic compression laser driving circuit compresses voltage pulses in the range of 1.5 microseconds at 20 kilovolts of amplitude to pulses in the range of 40 nanoseconds and 60 kilovolts of amplitude. The magnetic compression laser driving circuit includes a multi-stage magnetic switch where the last stage includes a switch having at least two turns which has larger saturated inductance with less core material so that the efficiency of the circuit and hence the laser is increased.
Large Magnetization at Carbon Surfaces
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided
Large Magnetization at Carbon Surfaces
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided
Summary report for nanoscale magnetics
Tobin, J.G.; Waddill, G.D.; Jankowski, A.F.; Tamura, E.; Sterne, P.A.; Pappas, D.P.; Tong, S.Y.
1993-09-23
We have probed the electronic, geometric, and magnetic nanoscale structure of ultrathin magnetic films, both monolayers and multilayers (Fe/Cu(001), FePt, FeCoPt, UFe{sub 2}, U-S). Techniques used included the MCD (magnetic circular dichroism)-variants of of x-ray absorption, core-level photoemission, and photoelectron diffraction. Progress has been made on nanoscale structure-property relations, in part of coupling of world-class experimentation and theoretical modeling. Feasibility of investigations of 5f magnetism using bulk uranium samples also has been demonstrated.
Measurements of magnetic field alignment
Kuchnir, M.; Schmidt, E.E.
1987-11-06
The procedure for installing Superconducting Super Collider (SSC) dipoles in their respective cryostats involves aligning the average direction of their field with the vertical to an accuracy of 0.5 mrad. The equipment developed for carrying on these measurements is described and the measurements performed on the first few prototypes SSC magnets are presented. The field angle as a function of position in these 16.6 m long magnets is a characteristic of the individual magnet with possible feedback information to its manufacturing procedure. A comparison of this vertical alignment characteristic with a magnetic field intensity (by NMR) characteristic for one of the prototypes is also presented. 5 refs., 7 figs.
Large Magnetization at Carbon Surfaces
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided
Large Magnetization at Carbon Surfaces
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided
Large Magnetization at Carbon Surfaces
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided
Large Magnetization at Carbon Surfaces
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Large Magnetization at Carbon Surfaces Print From organic matter to pencil lead, carbon is a versatile element. Now, another use has been found: magnets. One would not expect pure carbon to be magnetic, but for more than ten years scientists have suspected that carbon can be made to be magnetic by doping it with nonmagnetic materials, changing its order ever so slightly. Years ago, the first x-ray images obtained using the scanning transmission x-ray microscope at ALS Beamline 11.0.2 provided
Magnetic compression laser driving circuit
Ball, Don G. (Livermore, CA); Birx, Dan (Brentwood, CA); Cook, Edward G. (Livermore, CA)
1993-01-01
A magnetic compression laser driving circuit is disclosed. The magnetic compression laser driving circuit compresses voltage pulses in the range of 1.5 microseconds at 20 Kilovolts of amplitude to pulses in the range of 40 nanoseconds and 60 Kilovolts of amplitude. The magnetic compression laser driving circuit includes a multi-stage magnetic switch where the last stage includes a switch having at least two turns which has larger saturated inductance with less core material so that the efficiency of the circuit and hence the laser is increased.
Spherically symmetric analysis on open FLRW solution in non-linear massive gravity
Chiang, Chien-I; Izumi, Keisuke; Chen, Pisin E-mail: izumi@phys.ntu.edu.tw
2012-12-01
We study non-linear massive gravity in the spherically symmetric context. Our main motivation is to investigate the effect of helicity-0 mode which remains elusive after analysis of cosmological perturbation around an open Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. The non-linear form of the effective energy-momentum tensor stemming from the mass term is derived for the spherically symmetric case. Only in the special case where the area of the two sphere is not deviated away from the FLRW universe, the effective energy momentum tensor becomes completely the same as that of cosmological constant. This opens a window for discriminating the non-linear massive gravity from general relativity (GR). Indeed, by further solving these spherically symmetric gravitational equations of motion in vacuum to the linear order, we obtain a solution which has an arbitrary time-dependent parameter. In GR, this parameter is a constant and corresponds to the mass of a star. Our result means that Birkhoff's theorem no longer holds in the non-linear massive gravity and suggests that energy can probably be emitted superluminously (with infinite speed) on the self-accelerating background by the helicity-0 mode, which could be a potential plague of this theory.
Bounce cosmology from F(R) gravity and F(R) bigravity
Bamba, Kazuharu; Nojiri, Shin'ichi; Makarenko, Andrey N.; Odintsov, Sergei D.; Myagky, Alexandr N. E-mail: andre@tspu.edu.ru E-mail: nojiri@phys.nagoya-u.ac.jp
2014-01-01
We reconstruct F(R) gravity models with exponential and power-law forms of the scale factor in which bounce cosmology can be realized. We explore the stability of the reconstructed models with analyzing the perturbations from the background solutions. Furthermore, we study an F(R) gravity model with a sum of exponentials form of the scale factor, where the bounce in the early universe as well as the late-time cosmic acceleration can be realized in a unified manner. As a result, we build a second order polynomial type model in terms of R and show that it could be stable. Moreover, when the scale factor is expressed by an exponential form, we derive F(R) gravity models of a polynomial type in case of the non-zero spatial curvature and that of a generic type in that of the zero spatial curvature. In addition, for an exponential form of the scale factor, an F(R) bigravity model realizing the bouncing behavior is reconstructed. It is found that in both the physical and reference metrics the bouncing phenomenon can occur, although in general the contraction and expansion rates are different each other.
Dehghani, M.H.; Mann, R.B.
2006-05-15
We generalize the quasilocal definition of the stress-energy tensor of Einstein gravity to the case of third order Lovelock gravity, by introducing the surface terms that make the action well-defined. We also introduce the boundary counterterm that removes the divergences of the action and the conserved quantities of the solutions of third order Lovelock gravity with zero curvature boundary at constant t and r. Then, we compute the charged rotating solutions of this theory in n+1 dimensions with a complete set of allowed rotation parameters. These charged rotating solutions present black hole solutions with two inner and outer event horizons, extreme black holes or naked singularities provided the parameters of the solutions are suitably chosen. We compute temperature, entropy, charge, electric potential, mass and angular momenta of the black hole solutions, and find that these quantities satisfy the first law of thermodynamics. We find a Smarr-type formula and perform a stability analysis by computing the heat capacity and the determinant of Hessian matrix of mass with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that the system is thermally stable. This is commensurate with the fact that there is no Hawking-Page phase transition for black objects with zero curvature horizon.
Brane gravity, massless bulk scalar, and self-tuning of the cosmological constant
Kim, Jihn E.; Kyae, Bumseok; Shafi, Qaisar
2004-09-15
We show that a self-tuning mechanism of the cosmological constant could work in 5D noncompact space-time with a Z{sub 2} symmetry in the presence of a massless scalar field. The standard model matter fields live only on the 4D brane. The change of vacuum energy on the brane (brane cosmological constant) by, for instance, electroweak and QCD phase transitions, just gives rise to dynamical shifts of the profiles of the background metric and the scalar field in the extra dimension, keeping 4D space-time flat without any fine-tuning. To avoid naked singularities in the bulk, the brane cosmological constant should be negative. We introduce an additional brane-localized 4D Einstein-Hilbert term so as to provide the observed 4D gravity with the noncompact extra dimension. With a general form of the brane-localized gravity term allowed by the symmetries, the low energy Einstein gravity is successfully reproduced on the brane at long distances. We show this phenomenon explicitly for the case of vanishing bulk cosmological constant.
Smith, L.B.; Durney, T.E. Jr.
1991-04-23
Coal Technology Corporation (CTC) believes that the new CTC high gravity, high production, batch type centrifugal dryer technology can play a significant role in improving the product quality as well as costs of operation in coal processing plants. It is further believed that the new centrifugal dryer technology can form an important part in systems used to clean up millions of tons of coal fines in refuse piles and ponds. It is anticipated that the new centrifuge can become an important ancillary to the advanced deep cleaning processes for coal. Because of these convictions, CTC has been engaged in a pioneering research effort into the new art of drying fine clean coal in high gravity, high production, batch type of centrifuge, since 1981. This work has progressed to the point where the new centrifugal dryer technology is nearly ready for commercialization. It promises to provide needed fine coal drying capability at somewhat lower capital costs and at substantially lower operating costs than competitive systems. It also promises to do so with no detrimental effects on either the coal quality or the environment. The primary objective of this project is to prove the concept of a high gravity batch centrifuge for drying coal fines in a commercial coal processing plant environment. The proof of concept tests also include testing with a variety of coals from different regions. A further objective is to optimize the efficiency and the cost effectiveness of the new centrifugal dryer technology. 2 figs., 3 tabs.
Influence of heterogeneity on second-kind self-similar solutions for viscous gravity currents
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zheng, Zhong; Christov, IvanÂ C.; Stone, HowardÂ A.
2014-04-16
We report experimental, theoretical and numerical results on the effects of horizontal heterogeneities on the propagation of viscous gravity currents. We use two geometries to highlight these effects: (a) a horizontal channel (or crack) whose gap thickness varies as a power-law function of the streamwise coordinate; (b) a heterogeneous porous medium whose permeability and porosity have power-law variations. We demonstrate that two types of self-similar behaviours emerge as a result of horizontal heterogeneity: (a) a first-kind self-similar solution is found using dimensional analysis (scaling) for viscous gravity currents that propagate away from the origin (a point of zero permeability); (b)moreÂ Â» a second-kind self-similar solution is found using a phase-plane analysis for viscous gravity currents that propagate toward the origin. These theoretical predictions, obtained using the ideas of self-similar intermediate asymptotics, are compared with experimental results and numerical solutions of the governing partial differential equation developed under the lubrication approximation. All three results are found to be in good agreement.Â«Â less
Influence of heterogeneity on second-kind self-similar solutions for viscous gravity currents
Zheng, Zhong; Christov, IvanÂ C.; Stone, HowardÂ A.
2014-04-16
We report experimental, theoretical and numerical results on the effects of horizontal heterogeneities on the propagation of viscous gravity currents. We use two geometries to highlight these effects: (a) a horizontal channel (or crack) whose gap thickness varies as a power-law function of the streamwise coordinate; (b) a heterogeneous porous medium whose permeability and porosity have power-law variations. We demonstrate that two types of self-similar behaviours emerge as a result of horizontal heterogeneity: (a) a first-kind self-similar solution is found using dimensional analysis (scaling) for viscous gravity currents that propagate away from the origin (a point of zero permeability); (b) a second-kind self-similar solution is found using a phase-plane analysis for viscous gravity currents that propagate toward the origin. These theoretical predictions, obtained using the ideas of self-similar intermediate asymptotics, are compared with experimental results and numerical solutions of the governing partial differential equation developed under the lubrication approximation. All three results are found to be in good agreement.
Jiles, David C. (Ames, IA)
1991-04-16
A multiparameter magnetic inspection system for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen. The system therefore allows contemporaneous or simultaneous derivation of the plurality of different independent magnetic properties of the material which can then be processed to derive characteristics of the material.
Jiles, D.C.
1991-04-16
A multiparameter magnetic inspection system is disclosed for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen. The system therefore allows contemporaneous or simultaneous derivation of the plurality of different independent magnetic properties of the material which can then be processed to derive characteristics of the material. 1 figure.
SOLAR MAGNETIC TRACKING. IV. THE DEATH OF MAGNETIC FEATURES
Lamb, D. A.; Howard, T. A.; DeForest, C. E.; Parnell, C. E.; Welsch, B. T.
2013-09-10
The removal of magnetic flux from the quiet-Sun photosphere is important for maintaining the statistical steady state of the magnetic field there, for determining the magnetic flux budget of the Sun, and for estimating the rate of energy injected into the upper solar atmosphere. Magnetic feature death is a measurable proxy for the removal of detectable flux, either by cancellation (submerging or rising loops, or reconnection in the photosphere) or by dispersal of flux. We used the SWAMIS feature tracking code to understand how nearly 2 Multiplication-Sign 10{sup 4} magnetic features die in an hour-long sequence of Hinode/SOT/NFI magnetograms of a region of the quiet Sun. Of the feature deaths that remove visible magnetic flux from the photosphere, the vast majority do so by a process that merely disperses the previously detected flux so that it is too small and too weak to be detected, rather than completely eliminating it. The behavior of the ensemble average of these dispersals is not consistent with a model of simple planar diffusion, suggesting that the dispersal is constrained by the evolving photospheric velocity field. We introduce the concept of the partial lifetime of magnetic features, and show that the partial lifetime due to Cancellation of magnetic flux, 22 hr, is three times slower than previous measurements of the flux turnover time. This indicates that prior feature-based estimates of the flux replacement time may be too short, in contrast with the tendency for this quantity to decrease as resolution and instrumentation have improved. This suggests that dispersal of flux to smaller scales is more important for the replacement of magnetic fields in the quiet Sun than observed bipolar cancellation. We conclude that processes on spatial scales smaller than those visible to Hinode dominate the processes of flux emergence and cancellation, and therefore also the quantity of magnetic flux that threads the photosphere.
Probing non-standard gravity with the growth index: a background independent analysis
Steigerwald, Heinrich; Marinoni, Christian; Bel, Julien E-mail: jbel@cpt.univ-mrs.fr
2014-05-01
Measurements of the growth index of linear matter density fluctuations ?(z) provide a clue as to whether Einstein's field equations encompass gravity also on large cosmic scales, those where the expansion of the universe accelerates. We show that the information encoded in this function can be satisfactorily parameterized using a small set of coefficients ?{sub i}, in such a way that the true scaling of the growth index is recovered to better than 1% in most dark energy and dark gravity models. We find that the likelihood of current data, given this formalism and the ? Cold Dark Matter (?CDM) expansion model of Planck, is maximal for ?{sub 0} = 0.74{sup +0.44}{sub ?0.41} and ?{sub 1} = 0.01{sup +0.46}{sub ?0.46}, a measurement compatible with the ?CDM predictions (?{sub 0} = 0.545, ?{sub 1} = ?0.007). In addition, data tend to favor models predicting slightly less growth of structures than the Planck ?CDM scenario. The main aim of the paper is to provide a prescription for routinely calculating, in an analytic way, the amplitude of the growth indices ?{sub i} in relevant cosmological scenarios, and to show that these parameters naturally define a space where predictions of alternative theories of gravity can be compared against growth data in a manner which is independent from the expansion history of the cosmological background. As the standard ?-plane provides a tool to identify different expansion histories H(t) and their relation to various cosmological models, the ?-plane can thus be used to locate different growth rate histories f(t) and their relation to alternatives model of gravity. As a result, we find that the Dvali-Gabadadze-Porrati gravity model is rejected with a 95% confidence level. By simulating future data sets, such as those that a Euclid-like mission will provide, we also show how to tell apart ?CDM predictions from those of more extreme possibilities, such as smooth dark energy models, clustering quintessence or parameterized post-Friedmann cosmological models.
Dandina N. Rao; Subhash C. Ayirala; Madhav M. Kulkarni; Wagirin Ruiz Paidin; Thaer N. N. Mahmoud; Daryl S. Sequeira; Amit P. Sharma
2006-09-30
This is the final report describing the evolution of the project ''Development and Optimization of Gas-Assisted Gravity Drainage (GAGD) Process for Improved Light Oil Recovery'' from its conceptual stage in 2002 to the field implementation of the developed technology in 2006. This comprehensive report includes all the experimental research, models developments, analyses of results, salient conclusions and the technology transfer efforts. As planned in the original proposal, the project has been conducted in three separate and concurrent tasks: Task 1 involved a physical model study of the new GAGD process, Task 2 was aimed at further developing the vanishing interfacial tension (VIT) technique for gas-oil miscibility determination, and Task 3 was directed at determining multiphase gas-oil drainage and displacement characteristics in reservoir rocks at realistic pressures and temperatures. The project started with the task of recruiting well-qualified graduate research assistants. After collecting and reviewing the literature on different aspects of the project such gas injection EOR, gravity drainage, miscibility characterization, and gas-oil displacement characteristics in porous media, research plans were developed for the experimental work to be conducted under each of the three tasks. Based on the literature review and dimensional analysis, preliminary criteria were developed for the design of the partially-scaled physical model. Additionally, the need for a separate transparent model for visual observation and verification of the displacement and drainage behavior under gas-assisted gravity drainage was identified. Various materials and methods (ceramic porous material, Stucco, Portland cement, sintered glass beads) were attempted in order to fabricate a satisfactory visual model. In addition to proving the effectiveness of the GAGD process (through measured oil recoveries in the range of 65 to 87% IOIP), the visual models demonstrated three possible multiphase mechanisms at work, namely, Darcy-type displacement until gas breakthrough, gravity drainage after breakthrough and film-drainage in gas-invaded zones throughout the duration of the process. The partially-scaled physical model was used in a series of experiments to study the effects of wettability, gas-oil miscibility, secondary versus tertiary mode gas injection, and the presence of fractures on GAGD oil recovery. In addition to yielding recoveries of up to 80% IOIP, even in the immiscible gas injection mode, the partially-scaled physical model confirmed the positive influence of fractures and oil-wet characteristics in enhancing oil recoveries over those measured in the homogeneous (unfractured) water-wet models. An interesting observation was that a single logarithmic relationship between the oil recovery and the gravity number was obeyed by the physical model, the high-pressure corefloods and the field data.
Morin, R.L. )
1993-04-01
An arc of mafic and ultramafic rocks is mapped from Asik Mountain to Siniktanneyak Mountain in the northwestern Brooks Range of Alaska. Gravity data, although not very detailed, have been collected over the region and show some very conspicuous circular or oval gravity highs over portions of the mapped mafic-ultramafic bodies. Bodies which have large associated gravity anomalies are Asik Mountain (80 mGal), Avon Hills (20 mGal), Misheguk Mountain (30 mGal), and Siniktanneyak Mountain (20 mGal). Gabbros of the Siniktanneyak Mountain complex, where the gravity coverage is best, have densities of about 3.0 g/cm[sup 3] while the densities of the surrounding sedimentary rocks are about 2.6 g/cm[sup 3]. Volcanic rocks in the area have average densities of about 2.7 g/cm[sup 3]. Three-dimensional modeling indicates that the largest anomaly, on the southwestern part of the complex, could be caused by a polygonal prism of gabbro with vertical sides, about 6 km across and about 4.5 km deep. A smaller lobe of the anomaly on the northeast of the complex could be caused by another oblong polygonal prism about 4 km long and 2 km wide trending northeast and about 1.5 km deep. Modeling this anomaly with densities lower than gabbro would require greater thicknesses to produce the same anomaly. Modeling each anomaly along this arc in 2 1/2-dimensions shows many possible solutions using different body shapes and different density contrasts. There are several other gravity anomalies in this vicinity which could represent unexposed high density rocks. One such anomaly is in the Maiyumerak Mountains northeast of Asik Mountain (30 mGal). Another anomaly is to the northwest of Asik Mountain (20 mGal). There is also an anomaly at Uchugrak (20 mGal) east of Avan Hills. Although many of the anomalies in this region are poorly controlled, an attempt has been made to interpret the data to show possible solutions.
Magnetic polarizability of the nucleon
Ragusa, S.
1996-01-01
We derive an expression for the magnetic polarizability of the nucleon, as related to sums of products of its electromagnetic transition moments involving the electric and magnetic dipoles and mean-square radii, as well as the electric quadrupole moment. Two sum rules emerge from the calculation. {copyright} {ital 1995 The American Physical Society.}
Magnetic-field-dosimetry system
Lemon, D.K.; Skorpik, J.R.; Eick, J.L.
1981-01-21
A device is provided for measuring the magnetic field dose and peak field exposure. The device includes three Hall-effect sensors all perpendicular to each other, sensing the three dimensional magnetic field and associated electronics for data storage, calculating, retrieving and display.
Exploration of Artificial Frustrated Magnets
Samarth, Nitin; Schiffer, Peter
2015-02-17
This program encompasses experimental and theoretical studies of arrays of nanometer-scale magnets known as â€œartificial frustrated magnetsâ€. These magnets are small and closely spaced, so that their behavior as a collective group is complex and reveals insights into how such collections of interacting objects behave as a group. In particular, the placement of the magnets is such that the interactions between them are â€œfrustratedâ€, in that they compete with each other. These systems are analogs to a class of magnetic materials in which the lattice geometry frustrates interactions between individual atomic moments, and in which a wide range of novel physical phenomena have been recently observed. The advantage to studying the arrays is that they are both designable and resolvable: i.e., the experiments can control all aspects of the array geometry, and can also observe how individual elements of the arrays behave. This research program demonstrated a number of phenomena including the role of multiple collective interactions, the feasibility of using systems with their magnetism aligned perpendicular to the plane of the array, the importance of disorder in the arrays, and the possibility of using high temperatures to adjust the magnet orientations. All of these phenomena, and others explored in this program, add to the body of knowledge around collective magnetic behavior and magnetism in general. Aside from building scientific knowledge in an important technological area, with relevance to computing and memory, the program also gave critical support to the education of students working on the experiments.
Magnetic Resonance Facility (Fact Sheet)
Not Available
2012-03-01
This fact sheet provides information about Magnetic Resonance Facility capabilities and applications at NREL's National Bioenergy Center. Liquid and solid-state analysis capability for a variety of biomass, photovoltaic, and materials characterization applications across NREL. NREL scientists analyze solid and liquid samples on three nuclear magnetic resonance (NMR) spectrometers as well as an electron paramagnetic resonance (EPR) spectrometer.
Superconducting magnetic energy storage
Hassenzahl, W.
1988-08-01
Recent programmatic developments in Superconducting Magnetic Energy Storage (SMES) have prompted renewed and widespread interest in this field. In mid 1987 the Defense Nuclear Agency, acting for the Strategic Defense Initiative Office, issued a request for proposals for the design and construction of SMES Engineering Test Model (ETM). Two teams, one led by Bechtel and the other by Ebasco, are now engaged in the first phase of the development of a 10 to 20 MWhr ETM. This report presents the rationale for energy storage on utility systems, describes the general technology of SMES, and explains the chronological development of the technology. The present ETM program is outlined; details of the two projects for ETM development are described in other papers in these proceedings. The impact of high T/sub c/ materials on SMES is discussed. 69 refs., 3 figs., 3 tabs.
Permanent magnet multipole with adjustable strength
Halbach, Klaus (Berkeley, CA)
1985-01-01
Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling therebetween. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.
Permanent-magnet multipole with adjustable strength
Halbach, K.
1982-09-20
Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling there between. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.
The Butterfly Effect on Magnetic Vortices
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The Butterfly Effect on Magnetic Vortices The Butterfly Effect on Magnetic Vortices Print Tuesday, 20 January 2015 12:12 Miniature whirlpools of spins, also known as magnetic vortices, are currently a hot topic in magnetism research. In addition to providing insight into fundamental topological properties of materials, magnetic vortices show great potential as building blocks in advanced magnetic technologies. However, a completely reliable control over the vortex spin structure is mandatory
Disorder-Induced Microscopic Magnetic Memory
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Disorder-Induced Microscopic Magnetic Memory Disorder-Induced Microscopic Magnetic Memory Print Wednesday, 26 October 2005 00:00 The magnetic-recording industry deliberately introduces carefully controlled disorder into its materials to obtain the desired magnetic properties. But as the density of magnetic disks climbs, the size of the magnetic domains responsible for storage must decrease, posing new challenges. Beautiful theories based on random microscopic disorder have been developed over
Magnetic diagnostics for equilibrium reconstructions with eddy...
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Magnetic diagnostics for equilibrium reconstructions with eddy currents on the lithium tokamak experimenta) Citation Details In-Document Search Title: Magnetic diagnostics for...
National High Magnetic Field Laboratory moves closer
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researchers to carefully tune material parameters while perfectly reproducing the non-invasive magnetic field. Such high magnetic fields confine electrons to nanometer scale...
Disorder-Induced Microscopic Magnetic Memory
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Disorder-Induced Microscopic Magnetic Memory Print The magnetic-recording industry deliberately introduces carefully controlled disorder into its materials to obtain the desired...
Design Principles for Materials with Magnetic Functionality ...
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Design Principles for Materials with Magnetic Functionality Citation Details In-Document Search Title: Design Principles for Materials with Magnetic Functionality This report ...
Design Principles for Materials with Magnetic Functionality ...
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Design Principles for Materials with Magnetic Functionality Citation Details In-Document Search Title: Design Principles for Materials with Magnetic Functionality You are ...
Direct Imaging of Asymmetric Magnetization Reversal
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Direct Imaging of Asymmetric Magnetization Reversal Print The phenomenon of exchange bias has transformed how data is read on magnetic hard disks and created an explosion in their...
Direct Imaging of Asymmetric Magnetization Reversal
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Direct Imaging of Asymmetric Magnetization Reversal Direct Imaging of Asymmetric Magnetization Reversal Print Wednesday, 28 September 2005 00:00 The phenomenon of exchange bias has...
Category:Ground Magnetics | Open Energy Information
Ground Magnetics Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Geothermalpower.jpg Looking for the Ground Magnetics page? For detailed information on Ground...
Regenerator for Magnetic Refrigerants - Energy Innovation Portal
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Description Magnetic refrigeration is being investigated as an alternative to conventional ... These materials may thus have improved properties for magnetic refrigeration. As part of ...
Magnetic Pair Spectrometer Studies of Electromagnetic Transitions...
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Warburton, E. K. PHYSICS; BRANCHING RATIO; CARBON 13; CARBON 14; DECAY; DEUTERON BEAMS; ELECTRIC CHARGES; ENERGY; ENERGY LEVELS; ERRORS; LIFETIME; MAGNETIC FIELDS; MAGNETIC...
Magnetic Pair Spectrometer Studies of Electromagnetic Transitions...
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English Subject: PHYSICS; BRANCHING RATIO; CARBON 13; CARBON 14; DECAY; DEUTERON BEAMS; ELECTRIC CHARGES; ENERGY; ENERGY LEVELS; ERRORS; LIFETIME; MAGNETIC FIELDS; MAGNETIC...
COLLOQUIUM: Laboratory Study of Magnetic Reconnection: Recent...
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reconnection is a phenomenon of nature in which magnetic field lines change their topology in plasma and convert magnetic energy to particles by acceleration and heating. It is...
Taboada-Serrano, Patricia; Tsouris, Constantino; Contescu, Cristian I; McFarlane, Joanna
2013-10-08
The present invention provides magnetically responsive activated carbon, and a method of forming magnetically responsive activated carbon. The method of forming magnetically responsive activated carbon typically includes providing activated carbon in a solution containing ions of ferrite forming elements, wherein at least one of the ferrite forming elements has an oxidation state of +3 and at least a second of the ferrite forming elements has an oxidation state of +2, and increasing pH of the solution to precipitate particles of ferrite that bond to the activated carbon, wherein the activated carbon having the ferrite particles bonded thereto have a positive magnetic susceptibility. The present invention also provides a method of filtering waste water using magnetic activated carbon.
Periodic permanent magnet focused klystron
Ferguson, Patrick; Read, Michael; Ives, R Lawrence
2015-04-21
A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.
Magnetic cellulose-derivative structures
Walsh, M.A.; Morris, R.S.
1986-09-16
Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorption agents can be incorporated during the manufacture of the structure. 3 figs.
Magnetic microbes: Bacterial magnetite biomineralization
Prozorov, Tanya
2015-09-14
Magnetotactic bacteria are a diverse group of prokaryotes with the ability to orient and migrate along the magnetic field lines in search for a preferred oxygen concentration in chemically stratified water columns and sediments. These microorganisms produce magnetosomes, the intracellular nanometer-sized magnetic crystals surrounded by a phospholipid bilayer membrane, typically organized in chains. Magnetosomes have nearly perfect crystal structures with narrow size distribution and species-specific morphologies, leading to well-defined magnetic properties. As a result, the magnetite biomineralization in these organisms is of fundamental interest to diverse disciplines, from biotechnology to astrobiology. As a result, this article highlights recent advances in the understanding of the bacterial magnetite biomineralization.
Magnetic cellulose-derivative structures
Walsh, Myles A. (Falmouth, MA); Morris, Robert S. (Fairhaven, MA)
1986-09-16
Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorbtion agents can be incorporated during the manufacture of the structure.
Nuclear magnetic resonance contrast agents
Smith, P.H.; Brainard, J.R.; Jarvinen, G.D.; Ryan, R.R.
1997-12-30
A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC{sub 16}H{sub 14}N{sub 6}. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques. 10 figs.
Nuclear magnetic resonance contrast agents
Smith, Paul H.; Brainard, James R.; Jarvinen, Gordon D.; Ryan, Robert R.
1997-01-01
A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC.sub.16 H.sub.14 N.sub.6. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques.
Peralta, J.; López-Valverde, M. A.; Imamura, T.; Read, P. L.; Luz, D.; Piccialli, A.
2014-07-01
This paper is the first of a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases when the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this first part, only waves that are direct solutions of the generic dispersion relation are studied—acoustic and inertia-gravity waves. Concerning inertia-gravity waves, we found that in the cases of short horizontal wavelengths, null background wind, or propagation in the equatorial region, only pure gravity waves are possible, while for the limit of large horizontal wavelengths and/or null static stability, the waves are inertial. The correspondence between classical atmospheric approximations and wave filtering has been examined too, and we carried out a classification of the mesoscale waves found in the clouds of Venus at different vertical levels of its atmosphere. Finally, the classification of waves in exoplanets is discussed and we provide a list of possible candidates with cyclostrophic regimes.
Evaluation of an enhanced gravity-based fine-coal circuit for high-sulfur coal
Mohanty, M.K.; Samal, A.R.; Palit, A.
2008-02-15
One of the main objectives of this study was to evaluate a fine-coal cleaning circuit using an enhanced gravity separator specifically for a high sulfur coal application. The evaluation not only included testing of individual unit operations used for fine-coal classification, cleaning and dewatering, but also included testing of the complete circuit simultaneously. At a scale of nearly 2 t/h, two alternative circuits were evaluated to clean a minus 0.6-mm coal stream utilizing a 150-mm-diameter classifying cyclone, a linear screen having a projected surface area of 0.5 m{sup 2}, an enhanced gravity separator having a bowl diameter of 250 mm and a screen-bowl centrifuge having a bowl diameter of 500 mm. The cleaning and dewatering components of both circuits were the same; however, one circuit used a classifying cyclone whereas the other used a linear screen as the classification device. An industrial size coal spiral was used to clean the 2- x 0.6-mm coal size fraction for each circuit to estimate the performance of a complete fine-coal circuit cleaning a minus 2-mm particle size coal stream. The 'linear screen + enhanced gravity separator + screen-bowl circuit' provided superior sulfur and ash-cleaning performance to the alternative circuit that used a classifying cyclone in place of the linear screen. Based on these test data, it was estimated that the use of the recommended circuit to treat 50 t/h of minus 2-mm size coal having feed ash and sulfur contents of 33.9% and 3.28%, respectively, may produce nearly 28.3 t/h of clean coal with product ash and sulfur contents of 9.15% and 1.61 %, respectively.
Tewari, S.N.; Kumar, M.V.; Lee, J.E.; Curreri, P.A.
1990-11-01
Primary dendrite spacings, secondary dendrite spacings, and microsegregation have been examined in PWA-1480 single crystal specimens which were directionally solidified during parabolic maneuvers on the KC-135 aircraft. Experimentally observed growth rate and thermal gradient dependence of primary dendrite spacings are in good agreement with predictions from dendrite growth models for binary alloys. Secondary dendrite coarsening kinetics show a reasonable fit with the predictions from an analytical model proposed by Kirkwood for a binary alloy. The partition coefficients of tantalum, titanium, and aluminum are observed to be less than unity, while that for tungsten and cobalt are greater than unity. This is qualitatively similar to the nickel base binaries. Microsegregation profiles experimentally observed for PWA-1480 superalloy show a good fit with Bower, Brody, and Flemings model developed for binary alloys. Transitions in gravity levels do not appear to affect primary dendrite spacings. A trend of decreased secondary arm spacings with transition from high gravity to the low gravity period was observed at a growth speed of 0.023 cm s(exp -1). However, definite conclusions can only be drawn by experiments at lower growth speeds which make it possible to examine the side-branch coarsening kinetics over a longer duration. Such experiments, not possible due to the insufficient low-gravity time of the KC-135, may be carried out in the low-gravity environment of space.
Improved superconducting magnet wire
Schuller, I.K.; Ketterson, J.B.
1983-08-16
This invention is directed to a superconducting tape or wire composed of alternating layers of copper and a niobium-containing superconductor such as niobium of NbTi, Nb/sub 3/Sn or Nb/sub 3/Ge. In general, each layer of the niobium-containing superconductor has a thickness in the range of about 0.05 to 1.5 times its coherence length (which for Nb/sub 3/Si is 41 A) with each copper layer having a thickness in the range of about 170 to 600 A. With the use of very thin layers of the niobium composition having a thickness within the desired range, the critical field (H/sub c/) may be increased by factors of 2 to 4. Also, the thin layers of the superconductor permit the resulting tape or wire to exhibit suitable ductility for winding on a magnet core. These compositions are also characterized by relatively high values of critical temperature and therefore will exhibit a combination of useful properties as superconductors.
Probing low-scale quantum gravity with high-energy neutrinos
Ennadifi, Salah Eddine
2013-05-15
Motivated by the quantum structure of space-time at high scales M{sub QG}, we study the propagation behavior of the high-energy neutrino within the quantum gravity effect. We consider the possible induced dispersive effect and derive the resulting vacuum refraction index {eta}{sub vac}(E{sub {nu}}) Asymptotically-Equal-To 1 + E{sub {nu}}{sup 2}/M{sub QG}{sup 2}. Then, by referring to the SN1987A and basing on the recorded neutrino data we approach the corresponding scale M{sub QG} Asymptotically-Equal-To 10{sup 4} GeV.
Generalized uncertainty principle in f(R) gravity for a charged black hole
Said, Jackson Levi; Adami, Kristian Zarb
2011-02-15
Using f(R) gravity in the Palatini formularism, the metric for a charged spherically symmetric black hole is derived, taking the Ricci scalar curvature to be constant. The generalized uncertainty principle is then used to calculate the temperature of the resulting black hole; through this the entropy is found correcting the Bekenstein-Hawking entropy in this case. Using the entropy the tunneling probability and heat capacity are calculated up to the order of the Planck length, which produces an extra factor that becomes important as black holes become small, such as in the case of mini-black holes.
Five-dimensional black strings in Einstein-Gauss-Bonnet gravity
Kobayashi, Tsutomu; Tanaka, Takahiro
2005-04-15
We consider black-string-type solutions in five-dimensional Einstein-Gauss-Bonnet gravity. Numerically constructed solutions under static, axially symmetric and translationally invariant metric ansatz are presented. The solutions are specified by two asymptotic charges: mass of a black string and a scalar charge associated with the radion part of the metric. Regular black string solutions are found if and only if the two charges satisfy a fine-tuned relation, and otherwise the spacetime develops a singular event horizon or a naked singularity. We can also generate bubble solutions from the black strings by using a double Wick rotation.
Phantom-like behavior of a DGP-inspired Scalar-Gauss-Bonnet gravity
Nozari, Kourosh; Azizi, Tahereh; Setare, M.R. E-mail: t.azizi@umz.ac.ir
2009-10-01
We study the phantom-like behavior of a DGP-inspired braneworld scenario where curvature correction on the brane is taken into account. We include a possible modification of the induced gravity on the brane by incorporating higher order curvature terms of Gauss-Bonnet type. We investigate the cosmological implications of the model and we show that the normal branch of the scenario self-accelerates in this modified scenario without introducing any dark energy component. Also, a phantom-like behavior can be realized in this model without introducing any phantom field that suffers from serious difficulties such as violation of the null energy condition.
High-Accuracy Measurements of the Centre of Gravity of Avalanches in Proportional Chambers
DOE R&D Accomplishments [OSTI]
Charpak, G.; Jeavons, A.; Sauli, F.; Stubbs, R.
1973-09-24
In a multiwire proportional chamber the avalanches occur close to the anode wires. The motion of the positive ions in the large electric fields at the vicinity of the wires induces fast-rising positive pulses on the surrounding electrodes. Different methods have been developed in order to determine the position of the centre of the avalanches. In the method we describe, the centre of gravity of the pulse distribution is measured directly. It seems to lead to an accuracy which is limited only by the stability of the spatial distribution of the avalanches generated by the process being measured.
Toward the AdS/CFT gravity dual for high energy collisions. II. The stress
Office of Scientific and Technical Information (OSTI)
tensor on the boundary (Journal Article) | SciTech Connect II. The stress tensor on the boundary Citation Details In-Document Search Title: Toward the AdS/CFT gravity dual for high energy collisions. II. The stress tensor on the boundary In this second paper of the series, we calculate the stress tensor of excited matter, created by debris of high energy collisions at the boundary. The falling open strings, connected to receding charges, produce a nonzero stress tensor which we found
Lindemuth, I.R.; Ekdahl, C.A.; Kirkpatrick, R.C.
1996-12-31
Intermediate between magnetic confinement (MFE) and inertial confinement (ICF) in time and density scales is an area of research now known in the US as magnetized target fusion (MTF) and in Russian as MAGO (MAGnitnoye Obzhatiye--magnetic compression). MAGO/MTF uses a magnetic field and preheated, wall-confined plasma fusion fuel within an implodable fusion target. The magnetic field suppresses thermal conduction losses in the fuel during the target implosion and hydrodynamic compression heating process. In contrast to direct, hydrodynamic compression of initially ambient-temperature fuel (i.e., ICF), MAGO/MTF involves two steps: (a) formation of a warm (e.g., 100 eV or higher), magnetized (e.g., 100 kG) plasma within a fusion target prior to implosion; (b) subsequent quasi-adiabatic compression by an imploding pusher, of which a magnetically driven imploding liner is one example. In this paper, the authors present ongoing activities and potential future activities in this relatively unexplored area of controlled thermonuclear fusion.
Large Magnetization at Carbon Surfaces
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x-ray spectroscopy at ALS Beamline 4.0.2 to study the magnetism of proton-irradiated graphite surfaces in order to understand the effects of hydrogen (i.e. protons) on the...
Magnetically stimulated fluid flow patterns
Martin, Jim; Solis, Kyle
2014-03-06
Sandia National Laboratories' Jim Martin and Kyle Solis explain research on the effects of magnetic fields on fluid flows and how they stimulate vigorous flows. Fluid flow is a necessary phenomenon in everything from reactors to cooling engines in cars.
Magnetically stimulated fluid flow patterns
Martin, Jim; Solis, Kyle
2014-08-06
Sandia National Laboratories' Jim Martin and Kyle Solis explain research on the effects of magnetic fields on fluid flows and how they stimulate vigorous flows. Fluid flow is a necessary phenomenon in everything from reactors to cooling engines in cars.
Lensless Imaging of Magnetic Nanostructures
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of x-rays used. This promising method can be used at any coherent light source, including modern x-ray free-electron lasers, where ultrashort pulses would freeze-frame magnetic...
Magnet Girder Assembly and Installation
None
2013-07-17
It takes teamwork to assemble and install magnet girders for the storage ring of the National Synchrotron Light Source II. NSLS-II is now under construction at Brookhaven Lab.
Lensless Imaging of Magnetic Nanostructures
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Gambino, S. Mangin, S. Roy, and P. Fischer, "X-ray diffraction microscopy of magnetic structures," Phys. Rev. Lett. 107, 033904 (2011). ALS Science Highlight 244 ALSNews Vol. 329...
Lensless Imaging of Magnetic Nanostructures
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I. McNulty, R. Gambino, S. Mangin, S. Roy, and P. Fischer, "X-ray diffraction microscopy of magnetic structures," Phys. Rev. Lett. 107, 033904 (2011). ALS Science Highlight 244...
Magnetically focused liquid drop radiator
Botts, Thomas E. (Fairfax, VA); Powell, James R. (Shoreham, NY); Lenard, Roger (Redondo Beach, CA)
1986-01-01
A magnetically focused liquid drop radiator for application in rejecting rgy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.
Magnetically focused liquid drop radiator
Botts, T.E.; Powell, J.R.; Lenard, R.
1984-12-10
A magnetically focused liquid drop radiator for application in rejecting energy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.
Large Magnetization at Carbon Surfaces
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Now, researchers are using x-ray spectroscopy at ALS Beamline 4.0.2 to study the magnetism of proton-irradiated graphite surfaces in order to understand the effects of...
Magnetically insulated transmission line oscillator
Bacon, Larry D. (Albuquerque, NM); Ballard, William P. (Albuquerque, NM); Clark, M. Collins (Albuquerque, NM); Marder, Barry M. (Albuquerque, NM)
1988-01-01
A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields arfe produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap.
Magnetically insulated transmission line oscillator
Bacon, L.D.; Ballard, W.P.; Clark, M.C.; Marder, B.M.
1987-05-19
A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields are produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap. 11 figs.
Compact magnetic energy storage module
Prueitt, M.L.
1994-12-20
A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.
Condensed Matter and Magnet Science
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CMMS Condensed Matter and Magnet Science The group has a distinguished history of applying cutting-edge condensed matter physics research and high magnetic field science to mission-relevant materials challenges as well as fundamental investigations of emergent physical phenomena. Contact Us Group Leader (acting) Chuck Mielke Email Deputy Group Leader (acting) Leonardo Civale Email Deputy Group Leader (acting) Ross McDonald Email NHMFL-PFF Director Chuck Mielke Email Deputy NHMFL-PFF Director
Compact magnetic energy storage module
Prueitt, Melvin L.
1994-01-01
A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module.
Superconducting magnet development in Japan
Yasukochi, K.
1983-05-01
The present state of R and D works on the superconducting magnet and its applications in Japan are presented. On electrical rotating machines, 30 MVA superconducting synchronous rotary condenser (Mitsubishi and Fuji) and 50 MVA generator are under construction. Two ways of ship propulsion by superconducting magnets are developing. A superconducting magnetically levitated and linear motor propelled train ''MAGLEV'' was developed by the Japan National Railways (JNR). The superconducting magnet development for fusion is the most active field in Japan. The Cluster Test program has been demonstrated on a 10 T Nb/sub 3/Sn coil and the first coil of Large Coil Task in IEA collaboration has been constructed and the domestic test was completed in JAERI. These works are for the development of toroidal coils of the next generation tokamak machine. R and D works on superconducting ohmic heating coil are in progress in JAERI and ETL. The latter group has constructed 3.8 MJ pulsed coil. A high ramp rate of changing field in pulsed magnet, 200 T/s, has been tested successfully. High Energy Physics Laboratory (KEK) are conducting active works. The superconducting ..mu.. meson channel and ..pi.. meson channel have been constructed and are operating successfully. KEK has also a project of big accelerator named ''TRISTAN'', which is similar to ISABELLE project of BNL. Superconducting synchrotron magnets are developed for this project. The development of superconducting three thin wall solenoid has been started. One of them, CDF, is progressing under USA-Japan collaboration.
Optical sensor of magnetic fields
Butler, M.A.; Martin, S.J.
1986-03-25
An optical magnetic field strength sensor for measuring the field strength of a magnetic field comprising a dilute magnetic semi-conductor probe having first and second ends, longitudinally positioned in the magnetic field for providing Faraday polarization rotation of light passing therethrough relative to the strength of the magnetic field. Light provided by a remote light source is propagated through an optical fiber coupler and a single optical fiber strand between the probe and the light source for providing a light path therebetween. A polarizer and an apparatus for rotating the polarization of the light is provided in the light path and a reflector is carried by the second end of the probe for reflecting the light back through the probe and thence through the polarizer to the optical coupler. A photo detector apparatus is operably connected to the optical coupler for detecting and measuring the intensity of the reflected light and comparing same to the light source intensity whereby the magnetic field strength may be calculated.
MICE Spectrometer Magnet System Progress
Green, Michael A.; Virostek, Steve P.
2007-08-27
The first magnets for the muon ionization cooling experimentwill be the tracker solenoids that form the ends of the MICE coolingchannel. The primary purpose of the tracker solenoids is to provide auniform 4 T field (to better than +-0.3 percent over a volume that is 1meter long and 0.3 meters in diameter) spectrometer magnet field for thescintillating fiber detectors that are used to analyze the muons in thechannel before and after ionization cooling. A secondary purpose for thetracker magnet is the matching of the muon beam between the rest of theMICE cooling channel and the uniform field spectrometer magnet. Thetracker solenoid is powered by three 300 amp power supplies. Additionaltuning of the spectrometer is provided by a pair of 50 amp power suppliesacross the spectrometer magnet end coils. The tracker magnet will becooled using a pair of 4 K pulse tube coolers that each provide 1.5 W ofcooling at 4.2 K. Final design and construction of the tracker solenoidsbegan during the summer of 2006. This report describes the progress madeon the construction of the tracker solenoids.
Steering magnet design for a limited space
Okamura,M.; Fite, J.; Lodestro, V.; Raparia, D.; Ritter, J.
2009-05-04
We compare two extreme designs of steering magnets. The first one is a very thin steering magnet design which occupies only 6 mm in length and can be additionally installed as needed. The other is realized by applying extra coil windings to a quadrupole magnet and does not consume any length. The properties and the features of these steering magnets are discussed.
Ames Lab 101: Ultrafast Magnetic Switching
Jigang Wang
2013-06-05
Ames Laboratory physicists have found a new way to switch magnetism that is at least 1000 times faster than currently used in magnetic memory technologies. Magnetic switching is used to encode information in hard drives, magnetic random access memory and other computing devices. The discovery potentially opens the door to terahertz and faster memory speeds.
Signal enhancement using a switchable magnetic trap
Beer, Neil Reginald (Pleasanton, CA)
2012-05-29
A system for analyzing a sample including providing a microchannel flow channel; associating the sample with magnetic nanoparticles or magnetic polystyrene-coated beads; moving the sample with said magnetic nanoparticles or magnetic polystyrene-coated beads in the microchannel flow channel; holding the sample with the magnetic nanoparticles or magnetic polystyrene-coated beads in a magnetic trap in the microchannel flow channel; and analyzing the sample obtaining an enhanced analysis signal. An apparatus for analysis of a sample includes magnetic particles connected to the sample, a microchip, a flow channel in the microchip, a source of carrier fluid connected to the flow channel for moving the sample in the flow channel, an electromagnet trap connected to the flow line for selectively magnetically trapping the sample and the magnetic particles, and an analyzer for analyzing the sample.
Constraining models of f(R) gravity with Planck and WiggleZ power spectrum data
Dossett, Jason; Parkinson, David; Hu, Bin E-mail: hu@lorentz.leidenuniv.nl
2014-03-01
In order to explain cosmic acceleration without invoking ''dark'' physics, we consider f(R) modified gravity models, which replace the standard Einstein-Hilbert action in General Relativity with a higher derivative theory. We use data from the WiggleZ Dark Energy survey to probe the formation of structure on large scales which can place tight constraints on these models. We combine the large-scale structure data with measurements of the cosmic microwave background from the Planck surveyor. After parameterizing the modification of the action using the Compton wavelength parameter B{sub 0}, we constrain this parameter using ISiTGR, assuming an initial non-informative log prior probability distribution of this cross-over scale. We find that the addition of the WiggleZ power spectrum provides the tightest constraints to date on B{sub 0} by an order of magnitude, giving log{sub 10}(B{sub 0}) < ?4.07 at 95% confidence limit. Finally, we test whether the effect of adding the lensing amplitude A{sub Lens} and the sum of the neutrino mass ?m{sub ?} is able to reconcile current tensions present in these parameters, but find f(R) gravity an inadequate explanation.
Benini, Marco Dappiaggi, Claudio; Murro, Simone
2014-08-01
We discuss the quantization of linearized gravity on globally hyperbolic, asymptotically flat, vacuum spacetimes, and the construction of distinguished states which are both of Hadamard form and invariant under the action of all bulk isometries. The procedure, we follow, consists of looking for a realization of the observables of the theory as a sub-algebra of an auxiliary, non-dynamical algebra constructed on future null infinity ??. The applicability of this scheme is tantamount to proving that a solution of the equations of motion for linearized gravity can be extended smoothly to ??. This has been claimed to be possible provided that a suitable gauge fixing condition, first written by Geroch and Xanthopoulos [“Asymptotic simplicity is stable,” J. Math. Phys. 19, 714 (1978)], is imposed. We review its definition critically, showing that there exists a previously unnoticed obstruction in its implementation leading us to introducing the concept of radiative observables. These constitute an algebra for which a Hadamard state induced from null infinity and invariant under the action of all spacetime isometries exists and it is explicitly constructed.
Spin-orbit alignment for 110 day period KOI368.01 from gravity darkening
Ahlers, John P.; Seubert, Shayne A.; Barnes, Jason W.
2014-05-10
We fit the Kepler photometric light curve of the KOI-368 system using an oblate, gravity-darkened stellar model in order to constrain its spin-orbit alignment. We find that the system is relatively well-aligned with a sky-projected spin-orbit alignment of ? = 10° ± 2°, a stellar obliquity of ? = 3° ± 7°, and a true spin-orbit alignment of ? = 11° ± 3°. Although our measurement differs significantly from zero, the low value for ? is consistent with spin-orbit alignment. We also measure various transit parameters of the KOI-368 system: R {sub KOI-368} = 2.28 ± 0.02 R {sub ?}, R{sub p} = 1.83 ± 0.02 R {sub jup}, and i = 89.°221 ± 0.°013. This work shows that our gravity-darkened model can constrain long-period, well-aligned planets and M-class stars orbiting fast-rotators, allowing for measurement of a new subcategory of transiting bodies.
Hamiltonian dynamics of an exotic action for gravity in three dimensions
Escalante, Alberto Manuel-Cabrera, J.
2014-04-15
The Hamiltonian dynamics and the canonical covariant formalism for an exotic action in three dimensions are performed. By working with the complete phase space, we report a complete Hamiltonian description of the theory such as the extended action, the extended Hamiltonian, the algebra among the constraints, the Dirac’s brackets and the correct gauge transformations. In addition, we show that in spite of exotic action and tetrad gravity with a cosmological constant give rise to the same equations of motion, they are not equivalent, in fact, we show that their corresponding Dirac’s brackets are quite different. Finally, we construct a gauge invariant symplectic form which in turn represents a complete Hamiltonian description of the covariant phase space. -- Highlights: •We report a detailed Hamiltonian analysis for an exotic action of gravity. •We show that Palatini and exotic actions are not equivalent. •The exotic action is a non-commutative theory. •The fundamental gauge transformations of the theory are ?-deformed Poincaré transformations. •A Lorentz and gauge invariant symplectic two-form is constructed.
Preliminary gravity inversion model of basins east of Yucca Flat, Nevada Test Site, Nevada.
Geoffrey A. Phelps; Carter W. Roberts, and Barry C. Moring
2006-03-17
The Yucca Flat eastern extension study area, a 14 kilometer by 45 kilometer region contiguous to Yucca Flat on the west and Frenchman Flat on the south, is being studied to expand the boundary of the Yucca Flat hydrogeologic model. The isostatic residual gravity anomaly was inverted to create a model of the depth of the geologic basins within the study area. Such basins typically are floored by dense pre-Tertiary basement rocks and filled with less-dense Tertiary volcanic and sedimentary rocks and Quaternary alluvium, a necessary condition for the use of gravity modeling to predict the depth to the pre-Tertiary basement rocks within the basins. Three models were created: a preferred model to represent the best estimate of depth to pre-Tertiary basement rocks in the study area, and two end-member models to demonstrate the possible range of solutions. The preferred model predicts shallow basins, generally less than 1,000m depth, throughout the study area, with only Emigrant Valley reaching a depth of 1,100m. Plutonium valley and West Fork Scarp Canyon have maximum depths of 800m and 1,000m, respectively. The end-member models indicate that the uncertainty in the preferred model is less than 200m for most of the study area.
Thermodynamics of rotating black branes in (n+1)-dimensional Einstein-Born-Infeld gravity
Dehghani, M. H.; Sedehi, H. R. Rastegar
2006-12-15
We construct a new class of charged rotating solutions of (n+1)-dimensional Einstein-Born-Infeld gravity with cylindrical or toroidal horizons in the presence of cosmological constant and investigate their properties. These solutions are asymptotically (anti)-de Sitter and reduce to the solutions of Einstein-Maxwell gravity as the Born-Infeld parameters goes to infinity. We find that these solutions can represent black branes, with inner and outer event horizons, an extreme black brane or a naked singularity provided the parameters of the solutions are chosen suitably. We compute temperature, mass, angular momentum, entropy, charge and electric potential of the black brane solutions. We obtain a Smarr-type formula and show that these quantities satisfy the first law of thermodynamics. We also perform a stability analysis by computing the heat capacity and the determinant of Hessian matrix of mass of the system with infinite boundary with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that the system is thermally stable in the whole phase space. Also, we find that there exists an unstable phase when the finite size effect is taken into account.
Thermodynamics of rotating solutions in (n+1)-dimensional Einstein-Maxwell-dilaton gravity
Sheykhi, A.; Riazi, N.; Pakravan, J.; Dehghani, M. H.
2006-10-15
We construct a class of charged, rotating solutions of (n+1)-dimensional Einstein-Maxwell-dilaton gravity with cylindrical or toroidal horizons in the presence of Liouville-type potentials and investigate their properties. These solutions are neither asymptotically flat nor (anti)-de Sitter. We find that these solutions can represent black brane, with inner and outer event horizons, an extreme black brane or a naked singularity provided the parameters of the solutions are chosen suitably. We also compute temperature, entropy, charge, electric potential, mass and angular momentum of the black brane solutions, and find that these quantities satisfy the first law of thermodynamics. We find a Smarr-type formula and perform a stability analysis by computing the heat capacity in the canonical ensemble. We find that the system is thermally stable when the coupling constant between the dilaton and matter field {alpha}{<=}1, while for {alpha}>1 the system has an unstable phase. This shows that the dilaton field makes the solution unstable, while it is stable even in Lovelock gravity.
Thermodynamics of rotating solutions in Gauss-Bonnet-Maxwell gravity and the counterterm method
Dehghani, M. H.; Bordbar, G. H.; Shamirzaie, M.
2006-09-15
By a suitable transformation, we present the (n+1)-dimensional charged rotating solutions of Gauss-Bonnet gravity with a complete set of allowed rotation parameters which are real in the whole spacetime. We show that these charged rotating solutions present black hole solutions with two inner and outer event horizons, extreme black holes, or naked singularities provided the parameters of the solutions are chosen suitable. Using the surface terms that make the action well defined for Gauss-Bonnet gravity and the counterterm method for eliminating the divergences in action, we compute finite action of the solutions. We compute the conserved and thermodynamical quantities through the use of free energy and the counterterm method, and find that the two methods give the same results. We also find that these quantities satisfy the first law of thermodynamics. Finally, we perform a stability analysis by computing the heat capacity and the determinant of Hessian matrix of mass with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that the system is thermally stable. This is commensurate with the fact that there is no Hawking-Page phase transition for black objects with zero curvature horizon.
Smith, L.B.; Durney, T.E. Jr.
1990-07-24
Coal Technology Corporation (CTC) believes that the new CTC high gravity, high production, batch type centrifugal dryer technology can play a significant role in improving the product quality as well as costs of operation in coal processing plants. It is further believed that the new centrifugal dryer technology can form an important part in systems used to clean up the millions of tons of coal fines in refuse piles and ponds. It is anticipated that the new centrifuge can become an important ancillary to the advanced deep cleaning processes for coal. Because of these convictions, CTC has been engaged in a pioneering research effort into the new art of drying fine clean coal in high gravity, high production, batch type centrifuges, since 1981. This work has progressed to the point where the new centrifugal dryer technology is nearly ready for commercialization. It promises to provide needed fine coal drying capability at somewhat lower capital costs and at substantially lower operating costs than competitive systems. It also promises to do so with no detrimental effects on either the coal quality or the evironment. The primary objective of this project is to prove the concept in a commercial coal processing plant environment. The proof of concept tests will also include testing with a variety of coals from different regions. A further objective will be to optimize the efficiency and the cost effectiveness of the new centrifugal dryer technology.
Tewari, A.; Gokhale, A.M.; Gereman, R.M.
1999-10-08
Gravity affects microstructural evolution when a liquid phase is present during sintering. The effect of gravity on the three-dimensional coordination number distribution of tungsten grains in liquid phase sintered heavy alloy specimens is quantitatively characterized. A combination of montage serial sectioning, digital image processing, and unbiased stereological sampling procedures is used to estimate the coordination number distribution in three-dimensional microstructures. The microgravity environment decreases the mean coordination number. However, hardly any isolated grains are observed in the specimens, liquid phase sintered in a microgravity environment. The effect of microgravity on the coordination numbers mainly resides in its effect on the mean coordination number. In all specimens, there is a strong correlation between grain size and coordination number, which can be expressed as [D{sub c}/{bar D}]{sup 2} = C/C{sub 0} where C{sub 0} is the mean coordination number, {bar D} the global average size of the tungsten grains, and D{sub c} the average size of only those grains which have coordination number C.
Direct Imaging of Asymmetric Magnetization Reversal
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Direct Imaging of Asymmetric Magnetization Reversal Print The phenomenon of exchange bias has transformed how data is read on magnetic hard disks and created an explosion in their information storage density. However, it remains poorly understood, and even the fundamental mechanism of magnetic reversal for exchange-biased systems in changing magnetic fields is unclear. By using x-ray photoemission electron microscopy at the ALS to directly image the magnetic structure of an exchange-biased film,
Disorder-Induced Microscopic Magnetic Memory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Disorder-Induced Microscopic Magnetic Memory Print The magnetic-recording industry deliberately introduces carefully controlled disorder into its materials to obtain the desired magnetic properties. But as the density of magnetic disks climbs, the size of the magnetic domains responsible for storage must decrease, posing new challenges. Beautiful theories based on random microscopic disorder have been developed over the past ten years. To directly compare these theories with precise experiments,
Direct Imaging of Asymmetric Magnetization Reversal
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Direct Imaging of Asymmetric Magnetization Reversal Print The phenomenon of exchange bias has transformed how data is read on magnetic hard disks and created an explosion in their information storage density. However, it remains poorly understood, and even the fundamental mechanism of magnetic reversal for exchange-biased systems in changing magnetic fields is unclear. By using x-ray photoemission electron microscopy at the ALS to directly image the magnetic structure of an exchange-biased film,
Direct Imaging of Asymmetric Magnetization Reversal
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Direct Imaging of Asymmetric Magnetization Reversal Print The phenomenon of exchange bias has transformed how data is read on magnetic hard disks and created an explosion in their information storage density. However, it remains poorly understood, and even the fundamental mechanism of magnetic reversal for exchange-biased systems in changing magnetic fields is unclear. By using x-ray photoemission electron microscopy at the ALS to directly image the magnetic structure of an exchange-biased film,
Direct Imaging of Asymmetric Magnetization Reversal
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Direct Imaging of Asymmetric Magnetization Reversal Print The phenomenon of exchange bias has transformed how data is read on magnetic hard disks and created an explosion in their information storage density. However, it remains poorly understood, and even the fundamental mechanism of magnetic reversal for exchange-biased systems in changing magnetic fields is unclear. By using x-ray photoemission electron microscopy at the ALS to directly image the magnetic structure of an exchange-biased film,
Direct Imaging of Asymmetric Magnetization Reversal
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Direct Imaging of Asymmetric Magnetization Reversal Print The phenomenon of exchange bias has transformed how data is read on magnetic hard disks and created an explosion in their information storage density. However, it remains poorly understood, and even the fundamental mechanism of magnetic reversal for exchange-biased systems in changing magnetic fields is unclear. By using x-ray photoemission electron microscopy at the ALS to directly image the magnetic structure of an exchange-biased film,
Direct Imaging of Asymmetric Magnetization Reversal
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Direct Imaging of Asymmetric Magnetization Reversal Direct Imaging of Asymmetric Magnetization Reversal Print Wednesday, 28 September 2005 00:00 The phenomenon of exchange bias has transformed how data is read on magnetic hard disks and created an explosion in their information storage density. However, it remains poorly understood, and even the fundamental mechanism of magnetic reversal for exchange-biased systems in changing magnetic fields is unclear. By using x-ray photoemission electron
Disorder-Induced Microscopic Magnetic Memory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Disorder-Induced Microscopic Magnetic Memory Print The magnetic-recording industry deliberately introduces carefully controlled disorder into its materials to obtain the desired magnetic properties. But as the density of magnetic disks climbs, the size of the magnetic domains responsible for storage must decrease, posing new challenges. Beautiful theories based on random microscopic disorder have been developed over the past ten years. To directly compare these theories with precise experiments,
Disorder-Induced Microscopic Magnetic Memory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Disorder-Induced Microscopic Magnetic Memory Print The magnetic-recording industry deliberately introduces carefully controlled disorder into its materials to obtain the desired magnetic properties. But as the density of magnetic disks climbs, the size of the magnetic domains responsible for storage must decrease, posing new challenges. Beautiful theories based on random microscopic disorder have been developed over the past ten years. To directly compare these theories with precise experiments,
Disorder-Induced Microscopic Magnetic Memory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Disorder-Induced Microscopic Magnetic Memory Print The magnetic-recording industry deliberately introduces carefully controlled disorder into its materials to obtain the desired magnetic properties. But as the density of magnetic disks climbs, the size of the magnetic domains responsible for storage must decrease, posing new challenges. Beautiful theories based on random microscopic disorder have been developed over the past ten years. To directly compare these theories with precise experiments,
Disorder-Induced Microscopic Magnetic Memory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Disorder-Induced Microscopic Magnetic Memory Print The magnetic-recording industry deliberately introduces carefully controlled disorder into its materials to obtain the desired magnetic properties. But as the density of magnetic disks climbs, the size of the magnetic domains responsible for storage must decrease, posing new challenges. Beautiful theories based on random microscopic disorder have been developed over the past ten years. To directly compare these theories with precise experiments,
Magnetic reconnection | Princeton Plasma Physics Lab
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Magnetic reconnection Subscribe to RSS - Magnetic reconnection Magnetic reconnection (henceforth called "reconnection") refers to the breaking and reconnecting of oppositely directed magnetic field lines in a plasma. In the process, magnetic field energy is converted to plasma kinetic and thermal energy. PPPL team wins 80 million processor hours on nation's fastest supercomputer The U.S Department of Energy (DOE) has awarded a total of 80 million processor hours on the fastest
Local stress engineering of magnetic anisotropy in soft magnetic thin films
Office of Scientific and Technical Information (OSTI)
(Journal Article) | SciTech Connect Local stress engineering of magnetic anisotropy in soft magnetic thin films Citation Details In-Document Search Title: Local stress engineering of magnetic anisotropy in soft magnetic thin films The magnetic anisotropy of amorphous thin films was modified laterally by masked ion irradiation without alteration of the intrinsic magnetic properties. The changes were introduced by local ion implantation in a protection layer, causing additional stress-induced
Dynamic control of spin states in interacting magnetic elements
Jain, Shikha; Novosad, Valentyn
2014-10-07
A method for the control of the magnetic states of interacting magnetic elements comprising providing a magnetic structure with a plurality of interacting magnetic elements. The magnetic structure comprises a plurality of magnetic states based on the state of each interacting magnetic element. The desired magnetic state of the magnetic structure is determined. The active resonance frequency and amplitude curve of the desired magnetic state is determined. Each magnetic element of the magnetic structure is then subjected to an alternating magnetic field or electrical current having a frequency and amplitude below the active resonance frequency and amplitude curve of said desired magnetic state and above the active resonance frequency and amplitude curve of the current state of the magnetic structure until the magnetic state of the magnetic structure is at the desired magnetic state.
Keeton, Charles R.; Petters, A.O.
2005-11-15
We are developing a general, unified, and rigorous analytical framework for using gravitational lensing by compact objects to test different theories of gravity beyond the weak-deflection limit. In this paper we present the formalism for computing corrections to lensing observables for static, spherically symmetric gravity theories in which the corrections to the weak-deflection limit can be expanded as a Taylor series in one parameter, namely, the gravitational radius of the lens object. We take care to derive coordinate-independent expressions and compute quantities that are directly observable. We compute series expansions for the observables that are accurate to second order in the ratio {epsilon}={theta} /{theta}{sub E} of the angle subtended by the lens's gravitational radius to the weak-deflection Einstein radius, which scales with mass as {epsilon}{proportional_to}M {sup 1/2}. The positions, magnifications, and time delays of the individual images have corrections at both first and second order in {epsilon}, as does the differential time delay between the two images. Interestingly, we find that the first-order corrections to the total magnification and centroid position vanish in all gravity theories that agree with general relativity in the weak-deflection limit, but they can remain nonzero in modified theories that disagree with general relativity in the weak-deflection limit. For the Reissner-Nordstroem metric and a related metric from heterotic string theory, our formalism reveals an intriguing connection between lensing observables and the condition for having a naked singularity, which could provide an observational method for testing the existence of such objects. We apply our formalism to the galactic black hole and predict that the corrections to the image positions are at the level of 10 {mu}arc s (microarcseconds), while the correction to the time delay is a few hundredths of a second. These corrections would be measurable today if a pulsar were found to be lensed by the galactic black hole, and they should be readily detectable with planned missions like MAXIM.
Inviscid evolution of large amplitude filaments in a uniform gravity field
Angus, J. R.; Krasheninnikov, S. I.
2014-11-15
The inviscid evolution of localized density stratifications under the influence of a uniform gravity field in a homogeneous, ambient background is studied. The fluid is assumed to be incompressible, and the stratification, or filament, is assumed to be initially isotropic and at rest. It is shown that the center of mass energy can be related to the center of mass position in a form analogous to that of a solid object in a gravity field g by introducing an effective gravity field g{sub eff}, which is less than g due to energy that goes into the background and into non-center of mass motion of the filament. During the early stages of the evolution, g{sub eff} is constant in time and can be determined from the solution of a 1D differential equation that depends on the initial, radially varying density profile of the filament. For small amplitude filaments such that ?{sub 0} ? 1, where ?{sub 0} is the relative amplitude of the filament to the background, the early stage g{sub eff} scales linearly with ?{sub 0}, but as ?{sub 0}??,?g{sub eff}?g and is thus independent of ?{sub 0}. Fully nonlinear simulations are performed for the evolution of Gaussian filaments, and it is found that the time t{sub max}, which is defined as the time for the center of mass velocity to reach its maximum value U{sub max}, occurs very soon after the constant acceleration phase and so U{sub max}?g{sub eff}(t=0)t{sub max}. The simulation results show that U{sub max}?1/t{sub max}??(?{sub 0}) for ?{sub 0} ? 1, in agreement with theory and results from previous authors, but that U{sub max} and t{sub max} both scale approximately with ?(?{sub 0}) for ?{sub 0} ? 1. The fact that U{sub max} and t{sub max} have the same scaling with ?{sub 0} for large amplitude filaments is in agreement with the theory presented in this paper.
Magnetic microbes: Bacterial magnetite biomineralization
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Prozorov, Tanya
2015-09-14
Magnetotactic bacteria are a diverse group of prokaryotes with the ability to orient and migrate along the magnetic field lines in search for a preferred oxygen concentration in chemically stratified water columns and sediments. These microorganisms produce magnetosomes, the intracellular nanometer-sized magnetic crystals surrounded by a phospholipid bilayer membrane, typically organized in chains. Magnetosomes have nearly perfect crystal structures with narrow size distribution and species-specific morphologies, leading to well-defined magnetic properties. As a result, the magnetite biomineralization in these organisms is of fundamental interest to diverse disciplines, from biotechnology to astrobiology. As a result, this article highlights recent advances inmoreÂ Â» the understanding of the bacterial magnetite biomineralization.Â«Â less
Hyperon polarization and magnetic moments
Lach, J.
1993-12-01
Inclusively produced hyperons with significant polarization were first observed at Fermilab about seventeen years ago. This and subsequent experiments showed that {Lambda}{degree} were produced polarized while {bar {Lambda}}{degree} had no polarization in the same kinematical region. This set the stage for many experiments which showed that most hyperons are produced polarized. Recent Fermilab experiments have showed that this phenomena is even more complex and theoretical understanding is still lacking. Nevertheless polarized hyperon beams have been an extremely useful experimental tool in measuring hyperon magnetic moments. Recently, magnetic moment precession of channeled particles in bent crystals has been observed. This opens the possibility of measuring the magnetic moments of charmed baryons.
High performance magnetic bearing systems using high temperature superconductors
Abboud, R.G.
1998-05-05
Disclosed are a magnetic bearing apparatus and a method for providing at least one stabilizing force in a magnetic bearing structure with a superconducting magnetic assembly and a magnetic assembly, by providing a superconducting magnetic member in the superconducting magnetic assembly with a plurality of domains and arranging said superconducting magnetic member such that at least one domain has a domain C-axis vector alignment angularly disposed relative to a reference axis of the magnetic member in the magnetic assembly. 7 figs.
High performance magnetic bearing systems using high temperature superconductors
Abboud, Robert G. (Barrington Hills, IL)
1998-01-01
A magnetic bearing apparatus and a method for providing at least one stabilizing force in a magnetic bearing structure with a superconducting magnetic assembly and a magnetic assembly, by providing a superconducting magnetic member in the superconducting magnetic assembly with a plurality of domains and arranging said superconducting magnetic member such that at least one domain has a domain C-axis vector alignment angularly disposed relative to a reference axis of the magnetic member in the magnetic assembly.
Oji, L. N.
2015-10-01
August 2015, scale solids from the 16H Evaporator Gravity Drain Line (GDL) to the Tank 38H were delivered to SRNL for analysis. The desired analytical goal was to identify and confirm the crystalline structure of the scale material and determine if the form of the aluminosilicate mineral was consistent with previous analysis of the scale material from the GDL.
Wheel-type magnetic refrigerator
Barclay, J.A.
1983-10-11
The disclosure is directed to a wheel-type magnetic refrigerator capable of cooling over a large temperature range. Ferromagnetic or paramagnetic porous materials are layered circumferentially according to their Curie temperature. The innermost layer has the lowest Curie temperature and the outermost layer has the highest Curie temperature. The wheel is rotated through a magnetic field perpendicular to the axis of the wheel and parallel to its direction of rotation. A fluid is pumped through portions of the layers using inner and outer manifolds to achieve refrigeration of a thermal load. 7 figs.
Wheel-type magnetic refrigerator
Barclay, John A. (Los Alamos, NM)
1983-01-01
The disclosure is directed to a wheel-type magnetic refrigerator capable of cooling over a large temperature range. Ferromagnetic or paramagnetic porous materials are layered circumferentially according to their Curie temperature. The innermost layer has the lowest Curie temperature and the outermost layer has the highest Curie temperature. The wheel is rotated through a magnetic field perpendicular to the axis of the wheel and parallel to its direction of rotation. A fluid is pumped through portions of the layers using inner and outer manifolds to achieve refrigeration of a thermal load.
Wheel-type magnetic refrigerator
Barclay, J.A.
1982-01-20
The disclosure is directed to a wheel-type magnetic refrigerator capable of cooling over a large temperature range. Ferromagnetic or paramagnetic porous materials are layered circumferentially according to their Curie temperature. The innermost layer has the lowest Curie temperature and the outermost layer has the highest Curie temperature. The wheel is rotated through a magnetic field perpendicular to the axis of the wheel and parallel to its direction of rotation. A fluid is pumped through portions of the layers using inner and outer manifolds to achieve refrigeration of a thermal load.
Laminated magnet field coil sheath
Skaritka, J.R.
1987-05-15
A method for manufacturing a magnetic cable trim coil in a sheath assembly for use in a cryogenic particle accelerator. A precisely positioned pattern of trim coil turns is bonded to a flexible substrate sheath that is capable of withstanding cryogenic operating conditions. In the method of the invention the flexible substrate sheath, with the trim coil pattern precisely location relative to a bore tube assembly of an accelerator and is then bonded to the bore tube with a tape suitable for cryogenic application. The resultant assembly can be readily handled and installed within an iron magnet yoke assembly of a suitable cryogenic particle accelerator. 1 fig.
Resonant and non-resonant magnetic scattering
McWhan, D.B.; Hastings, J.B.; Kao, C.C.; Siddons, D.P.
1991-12-31
The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.
Resonant and non-resonant magnetic scattering
McWhan, D.B.; Hastings, J.B.; Kao, C.C.; Siddons, D.P.
1991-01-01
The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.
Magnetic refrigeration apparatus with heat pipes
Barclay, J.A.; Prenger, F.C. Jr.
1985-10-25
A magnetic refrigerator operating in the 4 to 20 K range utilizes heat pipes to transfer heat to and from the magnetic material at the appropriate points during the material's movement. In one embodiment circular disks of magnetic material can be interleaved with the ends of the heat pipes. In another embodiment a mass of magnetic material reciprocatingly moves between the end of the heat pipe or pipes that transmits heat from the object of cooling to the magnetic material and the end of the heat pipe or pipes that transmits heat from the magnetic material to a heat sink.
Magnetic refrigeration apparatus with heat pipes
Barclay, John A. (Los Alamos, NM); Prenger, Jr., F. Coyne (Madison, WI)
1987-01-01
A magnetic refrigerator operating in the 4 to 20 K range utilizes heat pipes to transfer heat to and from the magnetic material at the appropriate points during the material's movement. In one embodiment circular disks of magnetic material can be interleaved with the ends of the heat pipes. In another embodiment a mass of magnetic material reciprocatingly moves between the end of the heat pipe of pipes that transmits heat from the object of cooling to the magnetic material and the end of the heat pipe or pipes that transmits heat from the magnetic material to a heat sink.
Making permanent magnets more powerful and less expensive | The...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Making permanent magnets more powerful and less expensive Today's high-tech and clean energy capabilities are extremely reliant on powerful permanent magnets. Permanent magnets...