The dusty nuclear torus in NGC4151: constraints from Gemini NIFS observations
Riffel, Rogemar A; Mcgregor, Peter J
2009-01-01
We have used a near-infrared nuclear spectrum (covering the Z, J, H and K bands) of the nucleus of NGC 4151 obtained with the Gemini Near-infrared Integral Field Spectrograph (NIFS) and adaptive optics, to isolate and constrain the properties of a near-IR unresolved nuclear source whose spectral signature is clearly present in our data. The near-IR spectrum was combined with an optical spectrum obtained with the Space Telescope Imaging Spectrograph which was used to constrain the contribution of a power-law component. After subtraction of the power-law component, the near-IR continuum is well fitted by a blackbody function, with $T=1285\\pm50 $K, which dominates the nuclear spectrum -- within an aperture of radius 0$\\farcs$3 -- in the near-IR. We attribute the blackbody component to emission by a dusty structure, with hot dust mass $M_{\\rm HD}=(6.9\\pm 1.5) \\times10^{-4} {\\rm M_\\odot}$, not resolved by our observations, which provide only an upper limit for its distance from the nucleus of 4 pc. If the reddenin...
Gonzalez-Martin, O; Marquez, I; Rodríguez-Espinosa, J M; Acosta-Pulido, J A; Ramos-Almeida, C; Dultzin, D; Hernandez-Garcia, L; Ruschel-Dutra, D; Alonso-Herrero, A
2015-01-01
Most of the optically classified low ionisation narrow emission-line regions (LINERs) nuclei host an active galactic nuclei (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs; and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. We have compiled all the available low spectral resolution mid-IR spectra of LINERs from the IRS/Spitzer (40 LINERs). We have complemented this sample with Spitzer/IRS spectra of PGQSOs, S1s, S2s, and SBs nuclei. We have studied the AGN versus the starburst content in our sample using different indicators: the EW(PAH 6.2um), the strength of the silicate feature at 9.7um, and the steepness of the mid-IR spectra. In 25 out of the 40 LINERs (i.e., 62.5%) the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar t...
The impact of the dusty torus on obscured quasar halo mass measurements
DiPompeo, M. A.; Runnoe, J. C.; Hickox, R. C.; Myers, A. D.; Geach, J. E.
2016-07-01
Recent studies have found that obscured quasars cluster more strongly and are thus hosted by dark matter haloes of larger mass than their unobscured counterparts. These results pose a challenge for the simplest unification models, in which obscured objects are intrinsically the same as unobscured sources but seen through a dusty line of sight. There is general consensus that a structure like a `dusty torus' exists, meaning that this intrinsic similarity is likely the case for at least some subset of obscured quasars. However, the larger host halo masses of obscured quasars imply that there is a second obscured population that has an even higher clustering amplitude and typical halo mass. Here, we use simple assumptions about the host halo mass distributions of quasars, along with analytical methods and cosmological N-body simulations to isolate the signal from this population. We provide values for the bias and halo mass as a function of the fraction of the `non-torus-obscured' population. Adopting a reasonable value for this fraction of ˜25 per cent implies a non-torus-obscured-quasar bias that is much higher than the observed obscured quasar bias, because a large fraction of the obscured population shares the same clustering strength as the unobscured objects. For this non-torus-obscured population, we derive a bias of ˜3, and typical halo masses of ˜3 × 1013 M⊙ h-1 at z = 1. These massive haloes are likely the descendants of high-mass unobscured quasars at high redshift, and will evolve into members of galaxy groups at z = 0.
The Impact of the Dusty Torus on Obscured Quasar Halo Mass Measurements
DiPompeo, Michael A; Hickox, Ryan C; Myers, Adam D; Geach, James E
2016-01-01
Recent studies have found that obscured quasars cluster more strongly and are thus hosted by dark matter haloes of larger mass than their unobscured counterparts. These results pose a challenge for the simplest unification models, in which obscured objects are intrinsically the same as unobscured sources but seen through a dusty line of sight. There is general consensus that a structure like a "dusty torus" exists, meaning that this intrinsic similarity is likely the case for at least some subset of obscured quasars. However, the larger host halo masses of obscured quasars implies that there is a second obscured population that has an even higher clustering amplitude and typical halo mass. Here, we use simple assumptions about the host halo mass distributions of quasars, along with analytical methods and cosmological $N$-body simulations to isolate the signal from this population. We provide values for the bias and halo mass as a function of the fraction of the "non-torus obscured" population. Adopting a reas...
Investigating the dusty torus of Seyfert galaxies using SOFIA/FORCAST photometry
Fuller, Lindsay; Packham, Chris; Ramos-Almeida, Cristina; Alonso-Herrero, Almudena; Levenson, Nancy; Radomski, James; Ichikawa, Kohei; Garcia-Bernete, Ismael; Gonzalez-Martin, Omaira; Diaz-Santos, Tanio; Martinez-Parades, Mariela
2016-01-01
We present 31.5 micron imaging photometry of 11 nearby Seyfert galaxies observed from the Stratospheric Observatory For Infrared Astronomy (SOFIA) using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). We tentatively detect extended 31 micron emission for the first time in our sample. In combination with this new data set, subarcsecond resolution 1-18 micron imaging and 7.5-13 micron spectroscopic observations were used to compute the nuclear spectral energy distribution (SED) of each galaxy. We found that the turnover of the torus emission does not occur at wavelengths <31.5 micron, which we interpret as a lower-limit for the wavelength of peak emission. We used CLUMPY torus models to fit the nuclear infrared (IR) SED and infer trends in the physical parameters of the AGN torus for the galaxies in the sample. Including the 31.5 micron nuclear flux in the SED 1) reduces the number of clumpy torus models compatible with the data, and 2) modifies the model output for the outer radial exten...
Vazquez, Billy
The dusty torus is the key component in the Active Galactic Nuclei (AGN) Unification Scheme that explains the spectroscopic differences between Seyfert galaxies of types 1 and 2. The torus dust is heated by the nuclear source and emits the absorbed energy in the infrared (IR); but because of light travel times, the torus IR emission responds to variations of the nuclear ultraviolet/optical continuum with a delay that corresponds to the size of the emitting region. The results from a mid-infrared (MIR) monitoring campaign using the Spitzer Space Telescope and optical ground-based telescopes (B and V band imaging), which spanned over 2 years and covered a sample of 12 Seyfert galaxies, are presented. The aim was to constrain the distances from the nucleus to the regions in the torus emitting at wavelengths of 3.6 microm and 4.5 microm. MIR light curves showing the variability characteristics of these AGN are presented and the effects of photometric uncertainties on the time-series analysis of the light curves are discussed. Significant variability was observed in the IR light curves of 10 of 12 objects, with relative amplitudes ranging from ˜10% to ˜100% from their mean flux. The "reverberation lags" between the 3.6 microm and 4.5 microm IR bands were determined for the entire sample and between the optical and MIR bands for NGC6418. In NGC6418, the 3.6 microm and 4.5 microm fluxes lagged behind those of the optical continuum by 47.5+2.0-1.9) days and 62.5+2.5-2.9 days, respectively. This is consistent with the inferred lower limit to the sublimation radius for pure graphite grains at T=1800 K but smaller by a factor of 2 than the lower limit for dust grains with a "standard" interstellar medium (ISM) composition. There is evidence that the lags increased following approximately by a factor of 2 increase in luminosity, consistent with an increase in the sublimation radius.
Almeyda, Triana; Robinson, Andrew; Richmond, Michael; Vazquez, Billy; Nikutta, Robert
2017-07-01
The obscuring circumnuclear torus of dusty molecular gas is one of the major components of active galactic nuclei (AGN). The torus can be studied by analyzing the time response of its infrared (IR) dust emission to variations in the AGN continuum luminosity, a technique known as reverberation mapping. The IR response is the convolution of the AGN ultraviolet/optical light curve with a transfer function that contains information about the size, geometry, and structure of the torus. Here, we describe a new computer model that simulates the reverberation response of a clumpy torus. Given an input optical light curve, the code computes the emission of a 3D ensemble of dust clouds as a function of time at selected IR wavelengths, taking into account light travel delays. We present simulated dust emission responses at 3.6, 4.5, and 30 μm that explore the effects of various geometrical and structural properties, dust cloud orientation, and anisotropy of the illuminating radiation field. We also briefly explore the effects of cloud shadowing (clouds are shielded from the AGN continuum source). Example synthetic light curves have also been generated, using the observed optical light curve of the Seyfert 1 galaxy NGC 6418 as input. The torus response is strongly wavelength-dependent, due to the gradient in cloud surface temperature within the torus, and because the cloud emission is strongly anisotropic at shorter wavelengths. Anisotropic illumination of the torus also significantly modifies the torus response, reducing the lag between the IR and optical variations.
Collinson, James S.; Ward, Martin J.; Landt, Hermine; Done, Chris; Elvis, Martin; McDowell, Jonathan C.
2017-02-01
We continue our study of the spectral energy distributions (SEDs) of 11 active galactic nuclei (AGN) at 1.5 maximal spin (a* = 0.998) can only describe the data if the accretion disc is face-on. The outer accretion disc radii are well constrained in 8/11 objects and are found to be a factor ˜5 smaller than the self-gravity radii. We then extend our modelling campaign into the mid-IR regime with Wide-field Infrared Survey Explorer photometry, adding components for the host galaxy and dusty torus. Our estimates of the host galaxy luminosities are consistent with the MBH-bulge relationship, and the measured torus properties (covering factor and temperature) are in agreement with earlier work, suggesting a predominantly silicate-based grain composition. Finally, we deconvolve the optical-NIR spectra using our SED continuum model. We claim that this is a more physically motivated approach than using empirical descriptions of the continuum such as broken power laws. For our small sample, we verify previously noted correlations between emission linewidths and luminosities commonly used for single-epoch MBH estimates, and observe a statistically significant anticorrelation between [O III] equivalent width and AGN luminosity.
Sluse, D; Anguita, T; Wucknitz, O; Wambsganss, J
2013-01-01
Multiply-imaged quasars and AGNs observed in the mid-infrared (MIR) range are commonly assumed to be unaffected by the microlensing produced by the stars in their lensing galaxy. In this paper, we investigate the validity domain of this assumption. Indeed, that premise disregards microlensing of the accretion disc in the MIR range, and does not account for recent progress in our knowledge of the dusty torus. To simulate microlensing, we first built a simplified image of the quasar composed of an accretion disc, and of a larger ring-like torus. The mock quasars are then microlensed using an inverse ray-shooting code. We simulated the wavelength and size dependence of microlensing for different lensed image types and fraction of compact objects projected in the lens. This allows us to derive magnification probabilities as a function of wavelength, as well as to calculate the microlensing-induced deformation of the spectral energy distribution of the lensed images. We find that microlensing variations as large a...
Energy Technology Data Exchange (ETDEWEB)
Li, Zhenzhen; Zhou, Hongyan; Wang, Huiyuan; Liu, Bo; Liu, Wen-Juan; Pan, Xiang; Jiang, Peng [Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hao, Lei [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Ji, Tuo; Shi, Xiheng; Zhang, Shaohua, E-mail: lizz08@mail.ustc.edu.cn, E-mail: zhouhongyan@pric.org.cn, E-mail: haol@shao.ac.cn [Polar Research Institute of China, Jinqiao Rd. 451, Shanghai, 200136 (China)
2015-10-20
The existence of intermediate-width emission line regions (IELRs) in active galactic nuclei has been discussed for over two decades. A consensus, however, is yet to be arrived at due to the lack of convincing evidence for their detection. We present a detailed analysis of the broadband spectrophotometry of the partially obscured quasar OI 287. The ultraviolet intermediate-width emission lines (IELs) are very prominent, in high contrast to the corresponding broad emission lines (BELs) which are heavily suppressed by dust reddening. Assuming that the IELR is virialized, we estimated its distance to the central black hole to be ∼2.9 pc, similar to the dust sublimation radius of ∼1.3 pc. Photo-ionization calculations suggest that the IELR has a hydrogen density of ∼10{sup 8.8}–10{sup 9.4} cm{sup −3}, within the range of values quoted for the dusty torus near the sublimation radius. Both its inferred location and physical conditions suggest that the IELR originates from the inner surface of the dusty torus. In the spectrum of this quasar, we identified only one narrow absorption-line system associated with the dusty material. With the aid of photo-ionization model calculations, we found that the obscuring material might originate from an outer region of the dusty torus. We speculate that the dusty torus, which is exposed to the central ionizing source, may produce IELs through photo-ionization processes, as well as obscure BELs as a natural “coronagraph.” Such a “coronagraph” could be found in a large number of partially obscured quasars and may be a useful tool to study IELRs.
Collinson, James S; Landt, Hermine; Done, Chris; Elvis, Martin; McDowell, Jonathan C
2016-01-01
We continue our study of the spectral energy distributions (SEDs) of 11 AGN at 1.5 < z < 2.2, with optical-NIR spectra, X-ray data and mid-IR photometry. In a previous paper we presented the observations and models; in this paper we explore the parameter space of these models. We first quantify uncertainties on the black hole masses (M$_{\\rm BH}$) and degeneracies between SED parameters. The effect of BH spin is tested, and we find that while low to moderate spin values (a$_*$ $\\leq$ 0.9) are compatible with the data in all cases, maximal spin (a$_*$ = 0.998) can only describe the data if the accretion disc is face-on. The outer accretion disc radii are well constrained in 8/11 objects, and are found to be a factor ~5 smaller than the self-gravity radii. We then extend our modelling campaign into the mid-IR regime with WISE photometry, adding components for the host galaxy and dusty torus. Our estimates of the host galaxy luminosities are consistent with the M$_{\\rm BH}$-bulge relationship, and the meas...
Kraemer, Steven; Crenshaw, Michael; Dietrich, Matthias; Elitzur, Moshe; Gull, Theodore; Teplitz, Harry; Turner, Jane
2004-09-01
According to the unified model for AGN, Seyfert 1.8 and 1.9 galaxies are viewed at inclinations between those of Seyfert 1s (face-on) and Seyfert 2s (edge-on) with respect to the source of obscuration, typically envisioned as a dusty torus. This view is supported by the weak broad emission-line components of the Balmer lines, with ratios that are consistent with significant (E(B-V} ~ 1 mag) reddening of the broad-line region. Mid-IR spectra are the only means with which to probe the circumnuclear gas in these intermediate Seyferts and constrain the physical structure of the torus, such as its size, scale height, and clumpiness. Seyfert 1.8s and 1.9s also tend to possess relatively weak high ionization narrow lines (e.g. [Fe~VII] 6087 A) compared to Seyfert 1s, suggesting that the dusty circumnuclear gas may also obscure the inner narrow line region. We request Spitzer IRS spectra of 12 Seyfert 1.8s and 1.9s in order to 1) determine the temperature of the dust, and hence its radial distance from the central engine, to test for a torus origin, 2) determine the scale height and clumpiness of the torus atmosphere via the silicate 10 feature and comparisons with clumpy torus models, and 3) penetrate the obscuring gas via mid-IR emission lines, such as [Ne~V] 14.3 microns and [O~IV] 25.9 microns, to reveal the hidden high-ionization inner narrow line region. We have selected targets with host galaxies that are close to face-on, to minimize contamination of the mid-IR spectra by dust in their galactic planes. Among the more than 60 Seyferts in the Spitzer/IRS reserved target catalog, there are only a handful of true Seyfert 1.8s and 1.9s, and all of these have inclined (b/a < 0.5 ) host galaxies.
Li, Zhenzhen; Hao, Lei; Wang, Huiyuan; Ji, Tuo; Shi, Xiheng; Liu, Bo; Zhang, Shaohua; Liu, Wen-Juan; Pan, Xiang; Jiang, Peng
2015-01-01
The existence of intermediate-width emission line regions (IELRs) in active galactic nuclei has been discussed for over two decades. A consensus, however, is yet to be arrived at due to the lack of convincing evidence for their detection. We present a detailed analysis of the broadband spectrophotometry of the partially obscured quasar OI 287. The ultraviolet intermediate-width emission lines (IELs) are very prominent, in high contrast to the corresponding broad emission lines (BELs) which are heavily suppressed by dust reddening. Assuming that the IELR is virialized, we estimated its distance to the central black hole of $\\sim 2.9$ pc, similar to the dust sublimation radius of $\\sim 1.3$ pc. Photo-ionization calculations suggest that the IELR has a hydrogen density of $\\sim 10^{8.8}-10^{9.4} ~ \\rm cm^{-3}$, within the range of values quoted for the dusty torus near the sublimation radius. Both its inferred location and physical conditions suggest that the IELR originates from the inner surface of the dusty t...
Zhang, Shaohua; Zhou, Hongyan; Shi, Xiheng; Pan, Xiang; Wang, Ji; Jiang, Ning; Ji, Tuo; Jiang, Peng; Liu, Wenjuan; Wang, Huiyuan
2017-02-01
Broad emission line outflows of active galactic nuclei have been proposed for many years but are very difficult to quantitatively study because of the coexistence of the gravitationally bound and outflow emission. We present detailed analysis of a heavily reddened quasar, SDSS J000610.67+121501.2, whose normal ultraviolet broad emission lines (BELs) are heavily suppressed by the dusty torus as a natural “coronagraph,” and thus the blueshifted BELs (BBELs) can be reliably measured. The physical properties of the emission-line outflows are derived as follows: ionization parameter U∼ {10}-0.5, column density {N}{{H}}∼ {10}22.0 cm‑2, covering fraction of ∼0.1, and upper limit density of {n}{{H}}∼ {10}5.8 cm‑3. The outflow gases are located at least 41 pc away from the central engine, which suggests that they have expanded to the scale of the dust torus or beyond. Besides, Lyα shows a narrow symmetric component, to our surprise, which is undetected in any other lines. After inspecting the narrow emission line region and the star-forming region as the origin of the Lyα narrow line, we propose that the end result of outflows, diffusing gases in the larger region, acts as the screen of Lyα photons. Future high spatial resolution spectrometry and/or spectropolarimetric observations are needed to make a final clarification.
A mid-infrared look at the dusty nuclear environments of local active galaxies
Alonso Herrero, Almudena
2016-08-01
Active galactic nuclei are largely explained in the context of a unified theory, by which a geometrically and optically thick torus of gas and dust obscures the AGN central engine. The torus intercepts a substantial amount of flux from the central engine and and reradiates it in the infrared. There are still many open questions about the nature of the torus material and the role of nuclear (types of AGN from the modelling of the unresolved infrared emission with the CLUMPY torus models. I will also show that the molecules responsible for the 11.3micron PAH feature survive in the vicinity of the active nucleus and thus this PAH feature can be used to study the nuclear star formation activity in AGN.
Hoenig, S F
2009-01-01
(abridged) With the possibilities of high-spatial resolution imaging and spectroscopy as well as infrared (IR) interferometry, the dusty environments of active galactic nuclei (AGN) are now in reach of observations. In a series of papers, we aim for stepping towards characterizing physical properties of the dust torus by combining IR high-resolution observations with 3D radiative transfer models. In this first paper, we introduce an upgrade to our 3D radiative transfer model of clumpy dust tori. The models are presented as tools to translate classical and interferometric observations into characteristical parameters of the dust distribution. We compare model SEDs for different chemical and grain-size compositions of the dust and find that clouds with standard ISM dust and optical depth tau_V~50 appear in overall agreement with observed IR SEDs. By studying parameter dependencies, it is shown that type 1 AGN SEDs can be used to constrain the radial dust cloud distribution power-law index, a, as well as the mea...
Nuclear Dominated Accretion Flows in Two Dimensions. I. Torus Evolution with Parametric Microphysics
Fernández, Rodrigo
2012-01-01
We explore the evolution of radiatively inefficient accretion disks in which nuclear reactions are dynamically important (`Nuclear Dominated Accretion Flows', or NuDAFs). Examples of such disks are those generated by the merger of a white dwarf with a neutron star or black hole, or by the collapse of a rotating star. Here we present two-dimensional hydrodynamic simulations that systematically explore the effect of adding a single nuclear reaction to a viscous torus. The equation of state, anomalous shear stress, and nuclear reactions are given parametric forms. Our results point to the existence of two qualitatively different regimes of NuDAF evolution: (1) steady accretion with quiescent burning; or (2) detonation of the disk. These outcomes are controlled primarily by the ratio of the nuclear energy released to the enthalpy at the burning radius. Disks detonate if this ratio exceeds a critical value (~1), and if burning occurs in regions where neutrino cooling is unimportant. Thermonuclear runaways are seed...
Williams, Craig H.; Borowski, Stanley K.; Dudzinski, Leonard A.; Juhasz, Albert J.
1999-01-01
A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Initial requirements were for a human mission to Saturn with a>5% payload mass fraction and a one way trip time of less than one year. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 235 days, with an initial mass in low Earth orbit of 2,941 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including payload, central truss, nuclear reactor (including diverter and fuel injector), power conversion (including turbine, compressor, alternator, radiator, recuperator, and conditioning), magnetic nozzle, neutral beam injector, tankage, start/re-start reactor and battery, refrigeration, communications, reaction control, and in-space operations. Detailed assessment was done on reactor operations, including plasma characteristics, power balance, and component design.
Realizing "2001: A Space Odyssey": Piloted Spherical Torus Nuclear Fusion Propulsion
Williams, Craig H.; Dudzinski, Leonard A.; Borowski, Stanley K.; Juhasz, Albert J.
2005-01-01
A conceptual vehicle design enabling fast, piloted outer solar system travel was created predicated on a small aspect ratio spherical torus nuclear fusion reactor. The initial requirements were satisfied by the vehicle concept, which could deliver a 172 mt crew payload from Earth to Jupiter rendezvous in 118 days, with an initial mass in low Earth orbit of 1,690 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including artificial gravity payload, central truss, nuclear fusion reactor, power conversion, magnetic nozzle, fast wave plasma heating, tankage, fuel pellet injector, startup/re-start fission reactor and battery bank, refrigeration, reaction control, communications, mission design, and space operations. Detailed fusion reactor design included analysis of plasma characteristics, power balance/utilization, first wall, toroidal field coils, heat transfer, and neutron/x-ray radiation. Technical comparisons are made between the vehicle concept and the interplanetary spacecraft depicted in the motion picture 2001: A Space Odyssey.
Williams, Craig H.; Borowski, Stanley K.; Dudzinski, Leonard A.; Juhasz, Albert J.
1998-01-01
A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Initial requirements were for a human mission to Saturn with a greater than 5% payload mass fraction and a one way trip time of less than one year. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 235 days, with an initial mass in low Earth orbit of 2,941 mt. Engineering conceptual design, analysis, and assessment was performed on all ma or systems including payload, central truss, nuclear reactor (including divertor and fuel injector), power conversion (including turbine, compressor, alternator, radiator, recuperator, and conditioning), magnetic nozzle, neutral beam injector, tankage, start/re-start reactor and battery, refrigeration, communications, reaction control, and in-space operations. Detailed assessment was done on reactor operations, including plasma characteristics, power balance, power utilization, and component design.
The Infrared Nuclear Emission of Seyfert Galaxies on Parsec Scales: Testing the Clumpy Torus models
Almeida, Cristina Ramos; Espinosa, Jose Miguel Rodriguez; Herrero, Almudena Alonso; Ramos, Andres Asensio; Radomski, James T; Packham, Chris; Fisher, R Scott; Telesco, Charles M
2009-01-01
We present subarcsecond resolution mid-infrared (mid-IR) photometry in the wavelength range from 8 to 20 micron of eighteen Seyfert galaxies, reporting high spatial resolution nuclear fluxes for the entire sample. We construct spectral energy distributions (SEDs) that the AGN dominates adding near-IR measurements from the literature at similar angular resolution. The IR SEDs of intermediate-type Seyferts are flatter and present higher 10 to 18 micron ratios than those of Seyfert 2. We fit the individual SEDs with clumpy torus models using the in-house-developed BayesClumpy tool. The models reproduce the high spatial resolution measurements. Regardless of the Seyfert type, even with high spatial resolution data, near- to mid-IR SED fitting poorly constrains the radial extent of the torus. For the Seyfert 2, we find that edge-on geometries are more probable than face-on views, with a number of clouds along equatorial rays of N = 5-15. The 10 micron silicate feature is generally modeled in shallow absorption. Fo...
Reverberation Response Models of the Infrared Dust Emission from a Clumpy Torus
Almeyda, Triana
2016-08-01
The obscuring circum-nuclear dusty torus is a major component of AGN and yet, thus far, its shape, composition, and structure have not been well constrained by observations. However, using indirect methods such as reverberation mapping, the size and structure of the torus can be estimated through the time variability of the dusty torus emission in response to changes in the AGN luminosity. I will discuss the computer simulation that I have developed in order to extract structural information from the infrared light curves of 12 Type 1 AGN, obtained during a 2.5 year monitoring campaign using the Spitzer Space Telescope and several ground-based optical telescopes. Given an input optical light curve, the code computes the temporal response of the infrared emission spectrum of a 3D ensemble of dust clouds as a function of time. I will present simulations exploring the effects of various geometrical and structural properties, dust cloud orientation, and anisotropy of the illuminating radiation field on the dusty torus response at selected infrared wavelengths. I will also compare model infrared light curves to those observed for the recently discovered changing-look AGN, NGC 6418.
Energy Technology Data Exchange (ETDEWEB)
Fortov, Vladimir E; Khrapak, Aleksei G; Molotkov, Vladimir I; Petrov, Oleg F [Institute for High Energy Densities, Associated Institute for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation); Khrapak, Sergei A [Max-Planck-Institut fur Extraterrestrische Physik, Garching (Germany)
2004-05-31
The properties of dusty plasmas - low-temperature plasmas containing charged macroparticles - are considered. The most important elementary processes in dusty plasmas and the forces acting on dust particles are investigated. The results of experimental and theoretical investigations of different states of strongly nonideal dusty plasmas - crystal-like, liquid-like, gas-like - are summarized. Waves and oscillations in dusty plasmas, as well as their damping and instability mechanisms, are studied. Some results on dusty plasma investigated under microgravity conditions are presented. New directions of experimental research and potential applications of dusty plasmas are discussed. (reviews of topical problems)
Energy Technology Data Exchange (ETDEWEB)
Arbanas, Goran [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Elster, Charlotte [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Escher, Jutta [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nunes, Filomena [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thompson, Ian [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-08-28
The work of this collaboration during its existence is summarized. The mission of the TORUS Topical Collaboration was to develop new methods that advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct reaction calculations. This multi-institution collaborative effort was and remains directly relevant to three areas of interest: the properties of nuclei far from stability, microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory. The TORUS project focused on understanding the details of (d,p) reactions for neutron transfer to heavier nuclei. The bulk of the work fell into three areas: coupled channel theory, modeling (d,p) reactions with a Faddeev-AGS approach, and capture reactions.
Spectral line intensity and polarization in gas-dusty medium
Silant'ev, N A; Novikov, V V
2016-01-01
It is assumed that in Seyfert galaxies the gas-dusty medium exits near the centre in the form of a molecular and dusty torus and equatorial flow. These objects have spectral lines emission of hydrogen, helium and other atoms. We derived the spectral line radiative transfer equation for such media. This equation has dimensionless extinction factor of the form: $\\alpha(\
Gallagher, S C; Everett, J E; Keating, S; Deo, R P
2013-01-01
Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV absorption features. A convincing argument for radiation pressure driving this ionized outflow can be made within the dust sublimation radius. Beyond, radiation pressure is even more important, as high energy photons from the central engine can now push on dust grains. This physics underlies the dusty-wind model for the putative obscuring torus. Specifically, the dusty wind in our model is first launched from the outer accretion disk as a magneto-centrifugal wind and then accelerated and shaped by radiation pressure from the central continuum. Such a wind can plausibly account for both the necessary obscuring medium to explain the ratio of broad-to-narrow-line objects and the mid-infrared emission commonly seen in quasar spectral energy distributions. A convincing demonstration that large-scale, organized magnetic fields are pr...
Nolte, A; Schirren, C G
1997-06-01
Solitary or bilateral, symptomless exostoses on the lingual surface of the mandibule are called mandibular torus. It is mainly seen in young males and has a benign clinical course. The etiopathology is not known. Both genetic and environmental factors such as the anatomy of the lower jaw are considered. Syndromes associated with facial exostoses such as Proteus syndrome or Gardner's syndrome should be clinically excluded. A 40-year-old man with exostoses of the jaw is reported. With this case report we would like to draw attention to a disease which has rarely been described in the German dermatological literature.
Gravitational microlensing of AGN dusty tori
Stalevski, Marko; Popovic, Luka C; Baes, Maarten
2012-01-01
We investigated gravitational microlensing of AGN dusty tori in the case of lensed quasars in the infrared domain. The dusty torus is modeled as a clumpy two-phase medium. To obtain spectral energy distributions and images of tori at different wavelengths, we used the 3D Monte Carlo radiative transfer code SKIRT. A ray-shooting technique has been used to calculate microlensing magnification maps. We simulated microlensing by the stars in the lens galaxy for different configurations of the lensed system and different values of the torus parameters, in order to estimate (a) amplitudes and timescales of high magnification events, and (b) the influence of geometrical and physical properties of dusty tori on light curves in the infrared domain. We found that, despite their large size, dusty tori could be significantly affected by microlensing in some cases, especially in the near-infrared domain (rest-frame). The very long timescales of such events, in the range from several decades to hundreds of years, are limit...
Reverberation Mapping of the Dusty Tori in Active Galactic Nuclei
Richmond, Michael; Batcheldor, Daniel; Buchanan, Catherine; Capetti, Alessandro; Moshe, Elitzur; Gallimore, Jack; Horne, Keith; Kishimoto, Makoto; Marconi, Alessandro; Mason, Rachel; Maiolino, Robert; Netzer, Hagai; Packham, Christopher; Perez, Enrique; Peterson, Brad; Tadhunter, Clive; Robinson, Andrew; Stirpe, Giovanna; Storchi-Bergmann, Thaisa
2012-12-01
Our current understanding of the size and structure of AGN tori is weak, despite their central role in AGN unification models and their importance for studies of supermassive black hole demographics. We propose to use the warm phase of Spitzer to determine the sizes of circum-nuclear dust tori in AGN. To accomplish this we will extend an existing Spitzer monitoring campaign, coordinated with ground-based observations, to measure the 'light echo' as the dust emission responds to variations in the AGN optical/UV continuum. We have selected a sample of 12 bright type 1 nuclei in close proximity to the Spitzer Continuous Viewing Zone which can be observed for at least 70% of the 365 day cycle. We will observe each AGN every 30 days for the whole of Cycle 9, roughly doubling our existing baseline of one year, permitting us to identify optical-IR time lags of many months. We will continue our current ground based monitoring program using a variety of telescopes to determine the AGN light-curves in the optical. These observations will sample the torus more faithfully than previous measurements made in the K-band. Such high fidelity, continuously sampled IR light curves covering ~years cannot be obtained from the ground, and are needed because the expected reverberation timescales are hundreds of days. We will apply well developed techniques to determine the reverberation lag and therefore obtain the characteristic size of the torus in this sample which spans a range of black hole mass and Eddington ratio. Our team contains many leading experts in reverberation mapping of AGN and in the observational study and theoretical modeling of the physics of the dusty torus. We are requesting a total of 14 hours in the cycle to perform our observations. These observations will provide a stringent observational test of current models for the obscuring torus in AGN. The required measurements - long timescales, continuous monitoring in the near-infrared - are possible only with the
Vo, Theodore
2017-10-01
Torus canards are special solutions of fast/slow systems that alternate between attracting and repelling manifolds of limit cycles of the fast subsystem. A relatively new dynamic phenomenon, torus canards have been found in neural applications to mediate the transition from tonic spiking to bursting via amplitude-modulated spiking. In R3, torus canards are degenerate: they require one-parameter families of 2-fast/1-slow systems in order to be observed and even then, they only occur on exponentially thin parameter intervals. The addition of a second slow variable unfolds the torus canard phenomenon, making it generic and robust. That is, torus canards in fast/slow systems with (at least) two slow variables occur on open parameter sets. So far, generic torus canards have only been studied numerically, and their behaviour has been inferred based on averaging and canard theory. This approach, however, has not been rigorously justified since the averaging method breaks down near a fold of periodics, which is exactly where torus canards originate. In this work, we combine techniques from Floquet theory, averaging theory, and geometric singular perturbation theory to show that the average of a torus canard is a folded singularity canard. In so doing, we devise an analytic scheme for the identification and topological classification of torus canards in fast/slow systems with two fast variables and k slow variables, for any positive integer k. We demonstrate the predictive power of our results in a model for intracellular calcium dynamics, where we explain the mechanisms underlying a novel class of elliptic bursting rhythms, called amplitude-modulated bursting, by constructing the torus canard analogues of mixed-mode oscillations. We also make explicit the connection between our results here with prior studies of torus canards and torus canard explosion in R3, and discuss how our methods can be extended to fast/slow systems of arbitrary (finite) dimension.
Radiation-driven outflows from and radiative support in dusty tori of active galactic nuclei
Chan, Chi-Ho
2015-01-01
Substantial evidence points to dusty, geometrically thick tori obscuring the central engines of active galactic nuclei, but so far no mechanism satisfactorily explains why cool dust in the torus remains in a puffy geometry. Infrared (IR) radiation pressure on dust can play a significant role in shaping the torus, yet the separation of hydrodynamic evolution from radiative transfer (RT) in previous work on radiation-supported tori precluded a self-consistent picture. Here we present radiative hydrodynamics simulations of an initially smooth torus; we solve the hydrodynamics equations, the time-dependent multi-angle group IR RT equation, and the time-independent ultraviolet (UV) RT equation. IR radiation is highly anisotropic, leaving primarily through the central hole of the torus. The inner edge of the torus exhibits a break in axisymmetry under the influence of radiation and differential rotation. In addition, UV radiation pressure on dust launches a strong wind along the inner edge of the torus with speed $...
A mid-infrared exploration of the dusty environments of active galactic nuclei
Alonso-Herrero, Almudena
2013-01-01
We present the first results from a mid-infrared survey of local Active Galactic Nuclei (AGN) using the CanariCam (CC) instrument on the 10.4m Gran Telescopio Canarias (GTC). We are obtaining sub-arcsecond angular resolution (0.3-0.6 arcsec) mid-IR imaging and spectroscopic observations of a sample of 100 local AGN, which are complemented with data taken with T-ReCS, VISIR, and Michelle. The full sample contains approximately 140 AGN, covers nearly six orders of magnitude in AGN luminosity, and includes low-luminosity AGN (LLAGN), Seyfert 1s and 2s, QSO, radio galaxies, and (U)LIRGs. The main goals of this project are: (1) to test whether the properties of the dusty tori of the AGN Unified Model depend on the AGN type, (2) to study the nuclear star formation activity and obscuration of local AGN, and (3) to explore the role of the dusty torus in LLAGN.
Principal noncommutative torus bundles
DEFF Research Database (Denmark)
Echterhoff, Siegfried; Nest, Ryszard; Oyono-Oyono, Herve
2008-01-01
In this paper we study continuous bundles of C*-algebras which are non-commutative analogues of principal torus bundles. We show that all such bundles, although in general being very far away from being locally trivial bundles, are at least locally trivial with respect to a suitable bundle version...... of bivariant K-theory (denoted RKK-theory) due to Kasparov. Using earlier results of Echterhoff and Williams, we shall give a complete classification of principal non-commutative torus bundles up to equivariant Morita equivalence. We then study these bundles as topological fibrations (forgetting the group...... action) and give necessary and sufficient conditions for any non-commutative principal torus bundle being RKK-equivalent to a commutative one. As an application of our methods we shall also give a K-theoretic characterization of those principal torus-bundles with H-flux, as studied by Mathai...
Energy Technology Data Exchange (ETDEWEB)
Cobble, James Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-06-09
This document summarizes the Bumpy Torus Experiment as a viable fusion reactor concept. Conclusions reached include the following: In 30 years, order-of-magnitude technological advances have occurred in multiple areas of plasma heating and confinement. The ORNL bumpy torus of the 1970s was technology limited. Now that ITER is technology limited, an alternate concept is needed. A device built on such a concept should be current free, CW, modular, have a gentle shutdown, and demonstrable stability. The bumpy torus meets or has the potential to meet all of these criteria. Earlier, stability was not possible due to power limits; it has not been fully tested. It is time to revisit the bumpy-torus concept with a modest new machine.
Torus palatino, torus mandibular y exostosis maxilares
Directory of Open Access Journals (Sweden)
Ivan Alberto Manotas Arevalo
2013-12-01
Full Text Available Los huesos maxilares son parte de la estructura esquelética corporal por lo cual no son ajenos a las patologías que se presentan en ella. Algunas guardan semejanza entre sí, otras son muy singulares por sus características patognomónicas, por ejemplo, los torus palatinos, los torus mandibulares y las exostosis de los maxilares. Sin embargo, existen ideas especulativas acerca de su etiopatogenía, de los factores asociados, de su incidencia y prevalencia, de su necesidad de tratamiento, entre otras. El propósito de esta revisión es presentar la información existente sobre estas patologías en textos usados para la formación de profesionales de salud en nuestro medio y en el ámbito universal, y en otras publicaciones que hayan servido de soporte a las ideas concebidas acerca de los torus y las exostosis, haciendo énfasis en los aspectos diagnósticos. Se pretende que esta información sirva de orientación para investigaciones futuras.
An Asymmetric Noncommutative Torus
Dąbrowski, Ludwik; Sitarz, Andrzej
2015-09-01
We introduce a family of spectral triples that describe the curved noncommutative two-torus. The relevant family of new Dirac operators is given by rescaling one of two terms in the flat Dirac operator. We compute the dressed scalar curvature and show that the Gauss-Bonnet theorem holds (which is not covered by the general result of Connes and Moscovici).
Renormalization on noncommutative torus
D'Ascanio, D; Vassilevich, D V
2016-01-01
We study a self-interacting scalar $\\varphi^4$ theory on the $d$-dimensional noncommutative torus. We determine, for the particular cases $d=2$ and $d=4$, the nonlocal counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points towards the absence of any problems related to the UV/IR mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix $\\theta$.
Torus Bifurcation Under Discretization
Institute of Scientific and Technical Information of China (English)
邹永魁; 黄明游
2002-01-01
Parameterized dynamical systems with a simple zero eigenvalue and a couple of purely imaginary eigenvalues are considered. It is proved that this type of eigen-structure leads to torns bifurcation under certain nondegenerate conditions. We show that the discrete systems, obtained by discretizing the ODEs using symmetric, eigen-structure preserving schemes, inherit the similar torus bifurcation properties. Fredholm theory in Banach spaces is applied to obtain the global torns bifurcation. Our results complement those on the study of discretization effects of global bifurcation.
Renormalization on noncommutative torus
Energy Technology Data Exchange (ETDEWEB)
D' Ascanio, D.; Pisani, P. [Universidad Nacional de La Plata, Instituto de Fisica La Plata-CONICET, La Plata (Argentina); Vassilevich, D.V. [Universidade Federal do ABC, CMCC, Santo Andre, SP (Brazil); Tomsk State University, Department of Physics, Tomsk (Russian Federation)
2016-04-15
We study a self-interacting scalar φ{sup 4} theory on the d-dimensional noncommutative torus. We determine, for the particular cases d = 2 and d = 4, the counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points toward the absence of any problems related to the ultraviolet/infrared mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix θ. (orig.)
Renormalization on noncommutative torus
D'Ascanio, D.; Pisani, P.; Vassilevich, D. V.
2016-04-01
We study a self-interacting scalar \\varphi ^4 theory on the d-dimensional noncommutative torus. We determine, for the particular cases d=2 and d=4, the counterterms required by one-loop renormalization. We discuss higher loops in two dimensions and two-loop contributions to the self-energy in four dimensions. Our analysis points toward the absence of any problems related to the ultraviolet/infrared mixing and thus to renormalizability of the theory. However, we find another potentially troubling phenomenon which is a wild behavior of the two-point amplitude as a function of the noncommutativity matrix θ.
NGC 1068: No change in the mid-IR torus structure despite X-ray variability
López-Gonzaga, N; Bauer, F E; Tristram, K R W; Burtscher, L; Marinucci, A; Matt, G; Harrison, F A
2016-01-01
Context. Recent NuSTAR observations revealed a somewhat unexpected increase in the X-ray flux of the nucleus of NGC 1068. We expect the infrared emission of the dusty torus to react on the intrinsic changes of the accretion disk. Aims. We aim to investigate the origin of the X-ray variation by investigating the response of the mid-infrared environment. Methods. We obtained single-aperture and interferometric mid-infrared measurements and directly compared the measurements observed before and immediately after the X-ray variations. The average correlated and single-aperture fluxes as well as the differential phases were directly compared to detect a possible change in the structure of the nuclear emission on scales of $\\sim$ 2 pc. Results. The flux densities and differential phases of the observations before and during the X-ray variation show no significant change over a period of ten years. Possible minor variations in the infrared emission are $\\lesssim$ 8 %. Conclusions. Our results suggest that the mid-in...
Probing the Active Galactic Nuclei Unified Model Torus Properties in Seyfert Galaxies
Audibert, Anelise; Sales, Dinalva A; Pastoriza, Miriani G; Ruschel-Dutra, Daniel
2016-01-01
We studied the physical parameters of a sample comprising of all Spitzer/IRS public spectra of Seyfert galaxies in the mid-infrared (5.2-38$\\mu$m range) under the active galactic nuclei (AGN) unified model. We compare the observed spectra with $\\sim10^6$ CLUMPY model spectral energy distributions, which consider a torus composed of dusty clouds. We find a slight difference in the distribution of line-of-sight inclination angle, $i$, requiring larger angles for Seyfert 2 (Sy2) and a broader distribution for Seyfert 1 (Sy1). We found small differences in the torus angular width, $\\sigma$, indicating that Sy1 may host a slightly narrower torus than Sy2. The torus thickness, together with the bolometric luminosities derived, suggest a very compact torus up to $\\sim$6 pc from the central AGN. The number of clouds along the equatorial plane, $N$, as well the index of the radial profile, $q$, are nearly the same for both types. These results imply that the torus cloud distribution is nearly the same for type 1 and t...
Veilleux, S.; Meléndez, M.; Tripp, T. M.; Hamann, F.; Rupke, D. S. N.
2016-07-01
New near- and far-ultraviolet (NUV and FUV) Hubble Space Telescope spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ˜7000 km s-1), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na i D, He i, and Ca ii H and K lines, exhibiting broad blueshifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ˜90% of the observed continuum source at a distance ≲2-20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ˜22 (3) years and are unresolved on scales ˜40 (170) pc. These results favor an active galactic nucleus origin for the NUV-FUV line and continuum emission. The observed FUV line emission is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad line region seen through the dusty BAL screen. Our data are inconsistent with the recently proposed binary black hole model. We argue instead that Mrk 231 is the nearest example of weak-lined “wind-dominated” quasars with high Eddington ratios and geometrically thick (“slim”) accretion disks; these quasars are likely more common in the early universe.
Sheridan, T E
2010-01-01
One-dimensional and quasi-one-dimensional strongly-coupled dusty plasma rings have been created experimentally. Longitudinal (acoustic) and transverse (optical) dispersion relations for the 1-ring were measured and found to be in very good agreement with the theory for an unbounded straight chain of particles interacting through a Yukawa (i.e., screened Coulomb or Debye-H\\"uckel) potential. These rings provide a new system in which to study one-dimensional and quasi-one-dimensional physics.
Radiometric force in dusty plasmas
Ignatov, A M
2000-01-01
A radiofrequency glow discharge plasma, which is polluted with a certain number of dusty grains, is studied. In addition to various dusty plasma phenomena, several specific colloidal effects should be considered. We focus on radiometric forces, which are caused by inhomogeneous temperature distribution. Aside from thermophoresis, the role of temperature distribution in dusty plasmas is an open question. It is shown that inhomogeneous heating of the grain by ion flows results in a new photophoresis like force, which is specific for dusty discharges. This radiometric force can be observable under conditions of recent microgravity experiments.
Probing the active galactic nucleus unified model torus properties in Seyfert galaxies
Audibert, Anelise; Riffel, Rogério; Sales, Dinalva A.; Pastoriza, Miriani G.; Ruschel-Dutra, Daniel
2017-01-01
We studied the physical parameters of a sample comprising of all Spitzer/Infrared Spectrograph public spectra of Seyfert galaxies in the mid-infrared (5.2-38 μm range) under the active galactic nucleus (AGN) unified model. We compare the observed spectra with ˜106 CLUMPY model spectral energy distributions, which consider a torus composed of dusty clouds. We find a slight difference in the distribution of line-of-sight inclination angle, i, requiring larger angles for Seyfert 2 (Sy 2) and a broader distribution for Seyfert 1 (Sy 1). We found small differences in the torus angular width, σ, indicating that Sy 1 may host a slightly narrower torus than Sy 2. The torus thickness, together with the bolometric luminosities derived, suggests a very compact torus up to ˜6 pc from the central AGN. The number of clouds along the equatorial plane, N, as well the index of the radial profile, q, is nearly the same for both types. These results imply that the torus cloud distribution is nearly the same for type 1 and type 2 objects. The torus mass is almost the same for both types of activity, with values in the range of Mtor ˜ 104-107 M⊙. The main difference appears to be related to the clouds' intrinsic properties: type 2 sources present higher optical depths τV. The results presented here reinforce the suggestion that the classification of a galaxy may also depend on the intrinsic properties of the torus clouds rather than simply on their inclination. This is in contradiction with the simple geometric idea of the unification model.
Schmieding, Lasse C.; Lauga, Eric; Montenegro-Johnson, Thomas D.
2017-03-01
Phoretic swimmers provide new avenues to study nonequilibrium statistical physics and are also hailed as a promising technology for bioengineering at the cellular scale. Exact solutions for the locomotion of such swimmers have been restricted so far to spheroidal shapes. In this paper we solve for the flow induced by the canonical nonsimply connected shape, namely an axisymmetric phoretic torus. The analytical solution takes the form of an infinite series solution, which we validate against boundary element computations. For a torus of uniform chemical activity, confinement effects in the hole allow the torus to act as a pump, which we optimize subject to fixed particle surface area. Under the same constraint, we next characterize the fastest swimming Janus torus for a variety of assumptions on the surface chemistry. Perhaps surprisingly, none of the optimal tori occur in the limit where the central hole vanishes.
Veilleux, S; Tripp, T M; Hamann, F; Rupke, D S N
2016-01-01
New near- and far-ultraviolet (NUV and FUV) HST spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ~7000 km/s), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na I D, He I, and Ca II H and K lines, exhibiting broad blue-shifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ~90% of the observed continuum source at a distance less than ~2 - 20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ~2...
Sweeping Away the Mysteries of Dusty Continuous Winds in AGN
Keating, S K; Gallagher, S C; Deo, R P
2012-01-01
An integral part of the Unified Model for Active Galactic Nuclei (AGNs) is an axisymmetric obscuring medium, which is commonly depicted as a torus of gas and dust surrounding the central engine. However, a robust, dynamical model of the torus is required in order to understand the fundamental physics of AGNs and interpret their observational signatures. Here we explore self-similar, dusty disk-winds, driven by both magnetocentrifugal forces and radiation pressure, as an explanation for the torus. Using these models, we make predictions of AGN infrared (IR) spectral energy distributions (SEDs) from 2-100 microns by varying parameters such as: the viewing angle; the base column density of the wind; the Eddington ratio; the black hole mass; and the amount of power in the input spectrum emitted in the X-ray relative to that emitted in the UV/optical. We find that models with N_H,0 = 10^25 cm^-2, L/L_Edd = 0.1, and M_BH >= 10^8 Msun are able to adequately approximate the general shape and amount of power expected ...
Modeling the Europa plasma torus
Schreier, Ron; Eviatar, Aharon; Vasyliunas, Vytenis M.; Richardson, John D.
1993-12-01
The existence of a torus of plasma generated by sputtering from Jupiter's satellite Europa has long been suspected but never yet convincingly demonstrated. Temperature profiles from Voyager plasma observations indicate the presence of hot, possibly freshly picked-up ions in the general vicinity of the orbit of Europa, which may be interpreted as evidence for a local plasma torus. Studies of ion partitioning in the outer regions of the Io torus reveal that the oxygen to sulfur mixing ratio varies with radial distance; this may indicates that oxygen-rich matter is injected from a non-Io source, most probably Europa. We have constructed a quantitative model of a plasma torus near the orbit of Europa which takes into account plasma input from the Io torus, sputtering from the surface of Europa, a great number of ionization and charge exchange processes, and plasma loss by diffusive transport. When the transport time is chosen so that the model's total number density in consistent with the observed total plasma density, the contribution from Europa is found to be significant although not dominant. The model predicts in detail the ion composition, charge states, and the relative fractions of hot Europa-generated and (presumed) cold Io-generated ions. The results are generally consistent with observations from Voyager and can in principle (subject to limitations of data coverage) be confirmed in more detail by Ulysses.
Constraining the Europa Neutral Torus
Smith, Howard T.; Mitchell, Donald; mauk, Barry; Johnson, Robert E.; clark, george
2016-10-01
"Neutral tori" consist of neutral particles that usually co-orbit along with their source forming a toroidal (or partial toroidal) feature around the planet. The distribution and composition of these features can often provide important, if not unique, insight into magnetospheric particles sources, mechanisms and dynamics. However, these features can often be difficult to directly detect. One innovative method for detecting neutral tori is by observing Energetic Neutral Atoms (ENAs) that are generally considered produced as a result of charge exchange interactions between charged and neutral particles.Mauk et al. (2003) reported the detection of a Europa neutral particle torus using ENA observations. The presence of a Europa torus has extremely large implications for upcoming missions to Jupiter as well as understanding possible activity at this moon and providing critical insight into what lies beneath the surface of this icy ocean world. However, ENAs can also be produced as a result of charge exchange interactions between two ionized particles and in that case cannot be used to infer the presence of neutral particle population. Thus, a detailed examination of all possible source interactions must be considered before one can confirm that likely original source population of these ENA images is actually a Europa neutral particle torus. For this talk, we examine the viability that the Mauk et al. (2003) observations were actually generated from a neutral torus emanating from Europa as opposed to charge particle interactions with plasma originating from Io. These results help constrain such a torus as well as Europa source processes.
Compact magnetic confinement fusion: Spherical torus and compact torus
Directory of Open Access Journals (Sweden)
Zhe Gao
2016-05-01
Full Text Available The spherical torus (ST and compact torus (CT are two kinds of alternative magnetic confinement fusion concepts with compact geometry. The ST is actually a sub-category of tokamak with a low aspect ratio; while the CT is a toroidal magnetic configuration with a simply-connected geometry including spheromak and field reversed pinch. The ST and CT have potential advantages for ultimate fusion reactor; while at present they can also provide unique fusion science and technology contributions for mainstream fusion research. However, some critical scientific and technology issues should be extensively investigated.
Determining the torus covering factors for a sample of type 1 AGN in the local Universe
Ezhikode, Savithri H; Done, Chris; Ward, Martin; Dewangan, Gulab C; Misra, Ranjeev; Philip, Ninan Sajeeth
2016-01-01
The unification scheme of active galactic nuclei (AGN) proposes the presence of a dusty torus around the central source, governing the differences between AGN spectral properties. A fraction of the AGN luminosity is absorbed by the dusty torus and is re-radiated in the infrared (IR) band. Thus the fraction of the sky covered by the torus as seen from the central source, known as the covering factor f_c, can be obtained from the ratio of the IR to the bolometric luminosities of the source. However, because of the uncertainty in determining bolometric luminosities, the estimation of covering factors has proven difficult, especially in the local Universe where the peak of the observed spectral energy distributions (SEDs) lie in the ultraviolet. In this work, we determine the covering factors of an X-ray/optically selected sample of 51 type 1 AGN analysed by Jin et al. The bolometric luminosities of these sources can be derived using a self-consistent, energy-conserving model that estimates the contribution in th...
Ho, Choon-Lin; Hosotani, Yutaka
Starting from the quantum field theory of nonrelativistic matter on a torus interacting with Chern-Simons gauge fields, we derive the Schrödinger equation for an anyon system. The nonintegrable phases of the Wilson line integrals on a torus play an essential role. In addition to generating degenerate vacua, they enter in the definition of a many-body Schrödinger wave function in quantum mechanics, which can be defined as a regular function of the coordinates of anyons. It obeys a non-Abelian representation of the braid group algebra, being related to Einarsson’s wave function by a singular gauge transformation.
Breathing Modes in Dusty Plasma
Institute of Scientific and Technical Information of China (English)
王晓钢; 王爽; 潘秋惠; 刘悦; 贺明峰
2003-01-01
Acoustic breathing modes of dusty plasmas have been investigated in a cylindricalsystem with an axial symmetry. The linear wave solution and a "dispersion" relation were derived.It was found that in an infinite area, the mode is reduced to a "classical" dust acoustic wave inthe region away from the center. If the dusty plasma is confined in a finite region, however, thebreathing (or heart-beating) behavior would be found as observed in many experiments.
Garsi, Jerome-Philippe; Samson, Eric; Chablais, Laetitia; Zhivin, Sergey; Niogret, Christine; Laurier, Dominique; Guseva Canu, Irina
2014-12-01
This article discusses the availability and completeness of medical data on workers from the AREVA NC Pierrelatte nuclear plant and their possible use in epidemiological research on cardiovascular and metabolic disorders related to internal exposure to uranium. We created a computer database from files on 394 eligible workers included in an ongoing nested case-control study from a larger cohort of 2897 French nuclear workers. For each worker, we collected records of previous employment, job positions, job descriptions, medical visits, and blood test results from medical history. The dataset counts 9,471 medical examinations and 12,735 blood test results. For almost all of the parameters relevant for research on cardiovascular risk, data completeness and availability is over 90%, but it varies with time and improves in the latest time period. In the absence of biobanks, collecting and computerising available good-quality occupational medicine archive data constitutes a valuable alternative for epidemiological and aetiological research in occupational health. Biobanks rarely contain biological samples over an entire worker's carrier and medical data from nuclear industry archives might make up for unavailable biomarkers that could provide information on cardiovascular and metabolic diseases.
Rigidity theorems of Clifford Torus
Directory of Open Access Journals (Sweden)
SOUSA JR. LUIZ A. M.
2001-01-01
Full Text Available Let M be an n-dimensional closed minimally immersed hypersurface in the unit sphere Sn + 1. Assume in addition that M has constant scalar curvature or constant Gauss-Kronecker curvature. In this note we announce that if M has (n - 1 principal curvatures with the same sign everywhere, then M is isometric to a Clifford Torus .
Torus palatinus. Report of two cases
Directory of Open Access Journals (Sweden)
María Lorena Re Domínguez
2016-04-01
Full Text Available The torus is a non-neoplastic slow growing bone protuberance, which is usually manifested before the age of 30; Set in the hard palate is called “Torus Palatinus”, and located in the lower jaw – “Torus mandibularis”. In most cases, the diagnosis is usually incidental, during clinical examination, due to other reasons. The reason is that they are usually asymptomatic and patients are not aware of carrying a torus; hence the conservation treatment, unless it poses problems for the patient. We report two cases of incidental detected palatal torus in women.
Gohil, Raj
2015-01-01
Obscured AGNs provide an opportunity to study the material surrounding the central engine. Geometric and physical constraints on the absorber can be deduced from the reprocessed AGN emission. In particular, the obscuring gas may reprocess the nuclear X-ray emission producing a narrow Fe K$\\alpha$ line and a Compton reflection hump. In recent years, models of the X-ray reflection from an obscuring torus have been computed; however, although the reflecting gas may be dusty, the models do not yet take into account the effects of dust on the predicted spectrum. We study this problem by analyzing two sets of models, with and without the presence of dust, using the one dimensional photo-ionization code Cloudy. The calculations are performed for a range of column densities ($22 <{\\rm log}[N_H(\\rm cm^{-2})]< 24.5$ ) and hydrogen densities ( $6 <{\\rm log}[n_H(\\rm cm^{-3})]< 8$). The calculations show the presence of dust can enhance the Fe K$\\alpha$ equivalent width (EW) in the reflected spectrum by factor...
Turbulent complex (dusty) plasma
Zhdanov, Sergey; Schwabe, Mierk
2017-04-01
As a paradigm of complex system dynamics, solid particles immersed into a weakly ionized plasma, so called complex (dusty) plasmas, were (and continue to be) a subject of many detailed studies. Special types of dynamical activity have been registered, in particular, spontaneous pairing, entanglement and cooperative action of a great number of particles resulting in formation of vortices, self-propelling, tunneling, and turbulent movements. In the size domain of 1-10 mkm normally used in experiments with complex plasmas, the characteristic dynamic time-scale is of the order of 0.01-0.1 s, and these particles can be visualized individually in real time, providing an atomistic (kinetic) level of investigations. The low-R turbulent flow induced either by the instability in a complex plasma cloud or formed behind a projectile passing through the cloud is a typical scenario. Our simulations showed formation of a fully developed system of vortices and demonstrated that the velocity structure functions scale very close to the theoretical predictions. As an important element of self-organization, cooperative and turbulent particle motions are present in many physical, astrophysical, and biological systems. Therefore, experiments with turbulent wakes and turbulent complex plasma oscillations are a promising mean to observe and study in detail the anomalous transport on the level of individual particles.
Reverberation Mapping of the size of the Dusty Tori in Active Galactic Nuclei.
Axon, David; Batcheldor, Daniel; Buchanan, Catherine; Capetti, Alessandro; Elitzur, Moshe; Gallimore, Jack; Geballe, Thomas; Horne, Keith; Kishimoto, Makoto; Marconi, Alessandro; Mason, Rachel; Maiolino, Roberto; Netzer, Hagai; Packham, Christopher; Perez, Enrique; Peterson, Brad; Tadhunter, Clive; Richmond, Michael; Robinson, Andrew; Stirpe, Giovanna; Storchi-Bergmann, Thaisa
2011-05-01
Despite its central role in AGN unification models and its importance for studies of supermassive black hole demographics, our current understanding of the size and structure of AGN tori is weak. We propose to use the unique opportunity provided by the warm phase of Spitzer to determine the sizes of circum-nuclear dust tori in AGN. To accomplish this we will carry out a monitoring campaign, coordinated with ground-based observations, to measure the 'light echo' as the dust emission responds to variations in the AGN optical/UV continuum. We have selected a sample of 12 bright type 1 nuclei in close proximity to the Spitzer Continuous Viewing Zone which can be observed repeatedly with visibility windows for at least 70% of the ~400 day cycle and generally > 90% (10 objects )of the ~400 day cycle. We will observe each AGN with 3 day sampling on Spitzer for the whole of Cycle 8. We have in place a plan for a supporting ground based monitoring program using a variety of conventional and robotic telescopes, which will allow ?world-wide? coverage, to determine the AGN light-curves in the B band. These observations will more than double the number of AGN with simultaneous optical and NIR time-series data, providing well-sampled, high signal-to-noise light curves of both S1 and NLS1. Such high fidelity, continuously sampled lR light curves covering hundreds of days cannot be obtained from the ground, and are needed because the expected reverberation time scales are many tens of days (30-150). We will apply well developed techniques to determine the reverberation lag and therefore obtain the characteristic size of the torus in this sample which has diverse properties and samples a range of black hole mass and Eddington ratio. Our team contains many leading experts in reverberation mapping of AGN and in the observational study and theoretical modeling of the physics of the dusty torus. We are requesting a total of 196 hrs in the cycle to perform our observations.
Energy Technology Data Exchange (ETDEWEB)
Ichikawa, Kohei; Ueda, Yoshihiro [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Packham, Christopher; Lopez-Rodriguez, Enrique; Alsip, Crystal D. [Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249 (United States); Almeida, Cristina Ramos; Ramos, Andrés Asensio; González-Martín, Omaira [Instituto de Astrofísica de Canarias, C/Vía Láctea, s/n, E-38205 La Laguna, Tenerife (Spain); Alonso-Herrero, Almudena [Instituto de Física de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain); Díaz-Santos, Tanio [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States); Elitzur, Moshe [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506-0055 (United States); Hönig, Sebastian F. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Imanishi, Masatoshi [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Levenson, Nancy A. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Mason, Rachel E. [Gemini Observatory, Northern Operations Center, 670 N. A’ohoku Place, Hilo, HI 96720 (United States); Perlman, Eric S., E-mail: ichikawa@kusastro.kyoto-u.ac.jp [Department of Physics and Space Sciences, 150 W. University Blvd., Florida Institute of Technology, Melbourne, FL 32901 (United States)
2015-04-20
We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGNs) with clumpy torus models. We compiled high spatial resolution (∼0.3–0.7 arcsec) mid-IR (MIR) N-band spectroscopy, Q-band imaging, and nuclear near- and MIR photometry from the literature. Combining these nuclear near- and MIR observations, far-IR photometry, and clumpy torus models enables us to put constraints on the torus properties and geometry. We divide the sample into three types according to the broad line region (BLR) properties: type-1s, type-2s with scattered or hidden broad line region (HBLR) previously observed, and type-2s without any published HBLR signature (NHBLR). Comparing the torus model parameters gives us the first quantitative torus geometrical view for each subgroup. We find that NHBLR AGNs have smaller torus opening angles and larger covering factors than HBLR AGNs. This suggests that the chance to observe scattered (polarized) flux from the BLR in NHBLR could be reduced by the dual effects of (a) less scattering medium due to the reduced scattering volume given the small torus opening angle and (b) the increased torus obscuration between the observer and the scattering region. These effects give a reasonable explanation for the lack of observed HBLR in some type-2 AGNs.
Dusty Sheaths in Magnetized Plasmas
Institute of Scientific and Technical Information of China (English)
Yu. I. Chutov; O. Yu. Kravchenko; S. Masuzaki; A. Sagara; R. D. Smirnov; Yu. Tomita
2004-01-01
Parameters of self-consistent magnetized dusty sheaths are investigated using computer simulations of a temporal evolution of one-dimensional slab plasma with dust particles. The evolution is caused by a collection of electrons and ions by both a wall (electrode) and dust particles, which are initially immersed into plasma and distributed in front of the electrode. Obtained results show the existence of oscillations of a self-consistent potential in magnetized dusty sheaths including boundary potentials. Dust particles weaken magnetized sheaths and create additional sheaths close to a boundary of dust particles. The magnetic field does not influence on the dust particle charge.
ALMA Resolves the Torus of NGC 1068: Continuum and Molecular Line Emission
García-Burillo, S.; Combes, F.; Ramos Almeida, C.; Usero, A.; Krips, M.; Alonso-Herrero, A.; Aalto, S.; Casasola, V.; Hunt, L. K.; Martín, S.; Viti, S.; Colina, L.; Costagliola, F.; Eckart, A.; Fuente, A.; Henkel, C.; Márquez, I.; Neri, R.; Schinnerer, E.; Tacconi, L. J.; van der Werf, P. P.
2016-05-01
We used the Atacama Large Millimeter Array (ALMA) to map the emission of the CO(6-5) molecular line and the 432 μm continuum emission from the 300 pc sized circumnuclear disk (CND) of the nearby Seyfert 2 galaxy NGC 1068 with a spatial resolution of ˜4 pc. These observations spatially resolve the CND and, for the first time, image the dust emission, the molecular gas distribution, and the kinematics from a 7-10 pc diameter disk that represents the submillimeter counterpart of the putative torus of NGC 1068. We fitted the nuclear spectral energy distribution of the torus using ALMA and near- and mid-infrared (NIR/MIR) data with CLUMPY torus models. The mass and radius of the best-fit solution for the torus are both consistent with the values derived from the ALMA data alone: {M}{{gas}}{{torus}}=(1+/- 0.3)× {10}5 {M}⊙ and R torus = 3.5 ± 0.5 pc. The dynamics of the molecular gas in the torus show strong non-circular motions and enhanced turbulence superposed on a surprisingly slow rotation pattern of the disk. By contrast with the nearly edge-on orientation of the H2O megamaser disk, we found evidence suggesting that the molecular torus is less inclined (i = 34°-66°) at larger radii. The lopsided morphology and complex kinematics of the torus could be the signature of the Papaloizou-Pringle instability, long predicted to likely drive the dynamical evolution of active galactic nuclei tori.
Numerical simulation of dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Winske, D.
1995-09-01
The numerical simulation of physical processes in dusty plasmas is reviewed, with emphasis on recent results and unresolved issues. Three areas of research are discussed: grain charging, weak dust-plasma interactions, and strong dust-plasma interactions. For each area, we review the basic concepts that are tested by simulations, present some appropriate examples, and examine numerical issues associated with extending present work.
Rigid body dynamics on the Poisson torus
Richter, Peter H.
2008-11-01
The theory of rigid body motion with emphasis on the modifications introduced by a Cardan suspension is outlined. The configuration space is no longer SO(3) but a 3-torus; the equivalent of the Poisson sphere, after separation of an angular variable, is a Poisson torus. Iso-energy surfaces and their bifurcations are discussed. A universal Poincaré section method is proposed.
Bifurcation structure of successive torus doubling
Energy Technology Data Exchange (ETDEWEB)
Sekikawa, Munehisa [Department of Information Science, Faculty of Engineering, Utsunomiya University (Japan)]. E-mail: muse@aihara.jst.go.jp; Inaba, Naohiko [Department of Information Science, Faculty of Engineering, Utsunomiya University (Japan)]. E-mail: inaba@is.utsunomiya-u.ac.jp; Yoshinaga, Tetsuya [Department of Radiologic Science and Engineering, School of Health Sciences, The University of Tokushima (Japan)]. E-mail: yosinaga@medsci.tokushima-u.ac.jp; Tsubouchi, Takashi [Institute of Engineering Mechanics and Systems, University of Tsukuba (Japan)]. E-mail: tsubo@esys.tsukuba.ac.jp
2006-01-02
The authors discuss the 'embryology' of successive torus doubling via the bifurcation theory, and assert that the coupled map of a logistic map and a circle map has a structure capable of generating infinite number of torus doublings.
ALMA resolves the torus of NGC 1068: continuum and molecular line emission
Garcia-Burillo, S; Almeida, C Ramos; Usero, A; Krips, M; Alonso-Herrero, A; Aalto, S; Casasola, V; Hunt, L K; Martin, S; Viti, S; Colina, L; Costagliola, F; Eckart, A; Fuente, A; Henkel, C; Marquez, I; Neri, R; Schinnerer, E; Tacconi, L J; van der Werf, P P
2016-01-01
We have used the Atacama Large Millimeter Array (ALMA) to map the emission of the CO(6-5) molecular line and the 432 {\\mu}m continuum emission from the 300 pc-sized circumnuclear disk (CND) of the nearby Seyfert 2 galaxy NGC 1068 with a spatial resolution of ~4 pc. These observations spatially resolve the CND and image, for the first time, the dust emission and the molecular gas distribution and kinematics from a 7-10 pc-diameter disk that represents the submillimeter counterpart of the putative torus of NGC 1068. We fitted the nuclear spectral energy distribution of the torus using ALMA and near and mid-infrared (NIR/MIR) data with CLUMPY models. The mass and radius of the best-fit solution for the torus are both consistent with the values derived from the ALMA data alone: Mgas_torus=(1+-0.3)x10^5 Msun and Rtorus=3.5+-0.5 pc. The dynamics of the molecular gas in the torus show non-circular motions and enhanced turbulence superposed on the rotating pattern of the disk. The kinematic major axis of the CO torus...
Studies of accelerated compact toruses
Energy Technology Data Exchange (ETDEWEB)
Hartman, C.W.; Eddleman, J.; Hammer, J.H.
1983-01-04
In an earlier publication we considered acceleration of plasma rings (Compact Torus). Several possible accelerator configurations were suggested and the possibility of focusing the accelerated rings was discussed. In this paper we consider one scheme, acceleration of a ring between coaxial electrodes by a B/sub theta/ field as in a coaxial rail-gun. If the electrodes are conical, a ring accelerated towards the apex of the cone undergoes self-similar compression (focusing) during acceleration. Because the allowable acceleration force, F/sub a/ = kappaU/sub m//R where (kappa < 1), increases as R/sup -2/, the accelerating distance for conical electrodes is considerably shortened over that required for coaxial electrodes. In either case, however, since the accelerating flux can expand as the ring moves, most of the accelerating field energy can be converted into kinetic energy of the ring leading to high efficiency.
Reactor assessments of advanced bumpy torus configurations
Energy Technology Data Exchange (ETDEWEB)
Uckan, N.A.; Owen, L.W.; Spong, D.A.; Miller, R.L.; Ard, W.B.; Pipkins, J.F.; Schmitt, R.J.
1983-01-01
Recently, several configurational approaches and concept improvement schemes were introduced for enhancing the performance of the basic ELMO Bumpy Torus (EBT) concept and for improving its reactor potential. These configurations include planar racetrack and square geometries, Andreoletti coil systems, and bumpy torus-stellarator hybrids (which include twisted racetrack and helical axis stellarator-snakey torus). Preliminary evaluations of reactor implications of each of these configurations have been carried out based on magnetics (vacuum) calculations, transport and scaling relationships, and stability properties. Results indicate favorable reactor projections with a significant reduction in reactor physical size as compared to conventional EBT reactor designs carried out in the past.
Loop Quantum Cosmology on a Torus
Lamon, Raphael
2009-01-01
In this paper we study the effect of a torus topology on Loop Quantum Cosmology. We first derive the Teichmueller space parametrizing all possible tori using Thurston's theorem and construct a Hamiltonian describing the dynamics of these torus universes. We then compute the Ashtekar variables for a slightly simplified torus such that the Gauss constraint can be solved easily. We perform a canonical transformation so that the holomies along the edges of the torus reduce to a product between almost and strictly periodic functions of the new variables. The drawback of this transformation is that the components of the densitized triad become complicated functions of these variables. Nevertheless we find two ways of quantizing these components, which in both cases leads surprisingly to a continuous spectrum.
Acoustic propagation in a rigid torus
El-Raheb, M.; Wagner, P.
1982-01-01
The acoustic propagation in a rigid torus is analyzed using a Green's function method. Three types of surface elements are developed; a flat quadrilateral element used in modeling polygonal cavities, a curved conical element appropriate for surfaces with one curvature, and a toroidal element developed for such doubly curved surfaces as the torus. Curved elements are necessary since the acoustic pressure is sensitive to slope discontinuities between consecutive surface elements especially near cavity resonances. The acoustic characteristics of the torus are compared to those of a bend of square cross section for a frequency range that includes the transverse acoustic resonance. Two equivalences between the different sections are tested; the first conserves curvature and cross-sectional dimension while the second matches transverse resonance and duct volume. The second equivalence accurately matches the acoustic characteristics of the torus up to the cutoff frequency corresponding to a mode with two circumferential waves.
Zakharov equations in quantum dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Sayed, F. [Center for Risk Management and Safety Sciences, Yokohama National University, Yokohama 240-8501 (Japan); Vladimirov, S. V. [Center for Risk Management and Safety Sciences, Yokohama National University, Yokohama 240-8501 (Japan); Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya st. 13 Bld. 2, Moscow 125412 (Russian Federation); Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 (Russian Federation); Ishihara, O. [Center for Risk Management and Safety Sciences, Yokohama National University, Yokohama 240-8501 (Japan); Institute of Science and Technology Research, Chubu University, Kasugai 487-8501 (Japan)
2015-08-15
By generalizing the formalism of modulational interactions in quantum dusty plasmas, we derive the kinetic quantum Zakharov equations in dusty plasmas that describe nonlinear coupling of high frequency Langmuir waves to low frequency plasma density variations, for cases of non-degenerate and degenerate plasma electrons.
Torus bifurcations in multilevel converter systems
DEFF Research Database (Denmark)
Zhusubaliyev, Zhanybai T.; Mosekilde, Erik; Yanochkina, Olga O.
2011-01-01
embedded one into the other and with their basins of attraction delineated by intervening repelling tori. The paper illustrates the coexistence of three stable tori with different resonance behaviors and shows how reconstruction of these tori takes place across the borders of different dynamical regimes....... The paper also demonstrates how pairs of attracting and repelling tori emerge through border-collision torus-birth and border-collision torus-fold bifurcations. © 2011 World Scientific Publishing Company....
Mineral magnetism of dusty olivine
DEFF Research Database (Denmark)
Lappe, Sophie-Charlotte L. L.; Church, Nathan S.; Kasama, Takeshi
2011-01-01
The magnetic properties of olivine-hosted Fe-Ni particles have been studied to assess the potential of "dusty olivine" to retain a pre-accretionary remanence in chondritic meteorites. Both body-centered (bcc) and face-centered cubic (fcc) Fe-Ni phases were formed by reduction of a terrestrial...... SD particles using electron holography is presented. Combining the volume information with constraints on coercivity, we calculate the thermal relaxation characteristics of the particles and demonstrate that the high-coercivity component of remanance would remain stable for 4.6 Ga, even...
Radiation feedback in dusty clouds
Ishiki, Shohei
2016-01-01
We have investigated the impact of photoionization and radiation pressure on a dusty star-forming cloud by one-dimensional radiation hydrodynamic simulations, which include absorption and re-emission of photons by dust. We find that even in a moderately dusty cloud with the infrared optical depth of 0.15, radiation pressure has strong impact on driving an outflow, while the effect of radiation pressure is negligible in a dustless cloud. The radiation pressure on dust creates an HII region whose density is much lower than that in a dustless cloud where an outflow is driven by thermal pressure of ionized gas. Due to the radiation pressure, a shocked shell expands with high velocity, > 100 km s^-1. Absorption of re-emitted photons by dust plays a significant role in driving an outflow when the infrared optical depth becomes unity and it increases the importance of radiation pressure. The column density of clouds decreases with very short timescale owing to the shell expansion. Because of the decline of the infra...
High-velocity Bipolar Molecular Emission from an AGN Torus
Gallimore, Jack F.; Elitzur, Moshe; Maiolino, Roberto; Marconi, Alessandro; O'Dea, Christopher P.; Lutz, Dieter; Baum, Stefi A.; Nikutta, Robert; Impellizzeri, C. M. V.; Davies, Richard; Kimball, Amy E.; Sani, Eleonora
2016-09-01
We have detected in ALMA observations CO J=6\\to 5 emission from the nucleus of the Seyfert galaxy NGC 1068. The low-velocity (up to ±70 km s-1 relative to systemic) CO emission resolves into a 12 × 7 pc structure, roughly aligned with the nuclear radio source. Higher-velocity emission (up to ±400 km s-1) is consistent with a bipolar outflow in a direction nearly perpendicular (≃80°) to the nuclear disk. The position-velocity diagram shows that in addition to the outflow, the velocity field may also contain rotation about the disk axis. These observations provide compelling evidence in support of the disk-wind scenario for the active galactic nucleus obscuring torus.
High-Velocity Bipolar Molecular Emission from an AGN Torus
Gallimore, Jack F; Maiolino, Roberto; Marconi, Alessandro; O'Dea, Christopher P; Lutz, Dieter; Baum, Stefi A; Nikutta, Robert; Impellizzeri, C M V; Davies, Richard; Kimball, Amy E; Sani, Eleonora
2016-01-01
We have detected in ALMA observations CO J = 6 - 5 emission from the nucleus of the Seyfert galaxy NGC 1068. The low-velocity (up to +/- 70 km/s relative to systemic) CO emission resolves into a 12x7 pc structure, roughly aligned with the nuclear radio source. Higher-velocity emission (up to +/- 400 km/s) is consistent with a bipolar outflow in a direction nearly perpendicular (roughly 80 degrees) to the nuclear disk. The position-velocity diagram shows that in addition to the outflow, the velocity field may also contain rotation about the disk axis. These observations provide compelling evidence in support of the disk-wind scenario for the AGN obscuring torus.
The molecular H2 emission and the stellar kinematics in the nuclear region of the Sombrero galaxy
Menezes, R B
2015-01-01
We analyze the molecular H$_2$ emission and the stellar kinematics in a data cube of the nuclear region of M104, the Sombrero galaxy, obtained with NIFS on the Gemini-north telescope. After a careful subtraction of the stellar continuum, the only emission line we detected in the data cube was H$_2 \\lambda 21218$. An analysis of this emission revealed the existence of a rotating molecular torus/disk, aproximately co-planar with a dusty structure detected by us in a previous work. We interpret these two structures as being associated with the same obscuring torus/disk. The kinematic maps provided by the Penalized Pixel Fitting method revealed that the stellar kinematics in the nuclear region of M104 appears to be the result of the superposition of a "cold" rotating disk and a "hot" bulge. Using a model of a thin eccentric disk, we reproduced the main properties of the maps of the stellar radial velocity and of the stellar velocity dispersion, specially within a distance of 0.2" from the kinematic axis (in regio...
Radiation feedback in dusty clouds
Ishiki, Shohei; Okamoto, Takashi
2017-03-01
We have investigated the impact of photoionization and radiation pressure on a dusty star-forming cloud using one-dimensional radiation hydrodynamic simulations, which include absorption and re-emission of photons by dust. We find that, in a cloud of mass 105 M⊙ and radius 17 pc, the effect of radiation pressure is negligible when star formation efficiency is 2 per cent. The importance of radiation pressure increases with increasing star formation efficiency or an increasing dust-to-gas mass ratio. The net effect of radiation feedback, however, becomes smaller with the increasing dust-to-gas mass ratio, since the absorption of ultraviolet photons by dust grains suppresses photoionization and hence photoheating.
Directory of Open Access Journals (Sweden)
Masahiro Nakamura
2012-01-01
Full Text Available In this paper, we consider the following sliding puzzle called torus puzzle. In an m by n board, there are mn pieces numbered from 1 to mn. Initially, the pieces are placed in ascending order. Then they are scrambled by rotating the rows and columns without the player’s knowledge. The objective of the torus puzzle is to rearrange the pieces in ascending order by rotating the rows and columns. We provide a solution to this puzzle. In addition, we provide lower and upper bounds on the number of steps for solving the puzzle. Moreover, we consider a variant of the torus puzzle in which each piece is colored either black or white, and we present a hardness result for solving it.
Reactor assessments of advanced bumpy torus configurations
Energy Technology Data Exchange (ETDEWEB)
Uckan, N.A.; Owen, L.W.; Spong, D.A.; Miller, R.L.; Ard, W.B.; Pipkins, J.F.; Schmitt, R.J.
1984-02-01
Recently, several innovative approaches were introduced for enhancing the performance of the basic ELMO Bumpy Torus (EBT) concept and for improving its reactor potential. These include planar racetrack and square geometries, Andreoletti coil systems, and bumpy torus-stellarator hybrids (which include twisted racetrack and helical axis stellarator - snakey torus). Preliminary evaluations of reactor implications of each approach have been carried out based on magnetics (vacuum) calculations, transport and scaling relationships, and stability properties deduced from provisional configurations that implement the approach but are not necessarily optimized. Further optimization is needed in all cases to evaluate the full potential of each approach. Results of these studies indicate favorable reactor projections with a significant reduction in reactor physical size as compared to conventional EBT reactor designs carried out in the past.
Screening length in dusty plasma crystals
Nikolaev, V. S.; Timofeev, A. V.
2016-11-01
Particles interaction and value of the screening length in dusty plasma systems are of great interest in dusty plasma area. Three inter-particle potentials (Debye potential, Gurevich potential and interaction potential in the weakly collisional regime) are used to solve equilibrium equations for two dusty particles suspended in a parabolic trap. The inter-particle distance dependence on screening length, trap parameter and particle charge is obtained. The functional form of inter-particle distance dependence on ion temperature is investigated and compared with experimental data at 200-300 K in order to test used potentials applicability to dusty plasma systems at room temperatures. The preference is given to the Yukawa-type potential including effective values of particle charge and screening length. The estimated effective value of the screening length is 5-15 times larger than the Debye length.
Diffusion on the torus for Hamiltonian maps
Energy Technology Data Exchange (ETDEWEB)
Siboni, S. (Istituto di Fisica dell' Universita Bologna (Italy) Centre de Physique Theorique, Marseille (France)); Turchetti, G. (Istituto di Fisica dell' Universita Bologna (Italy)); Vaienti, S. (Centre de Physique Theorique, Marseille (France) Universite de Toulon et du Var (France))
1994-04-01
For a mapping of the torus T[sup 2] the authors propose a definition of the diffusion coefficient D suggested by the solution of the diffusion equation on T[sup 2]. The definition of D, based on the limit of moments of the invariant measure, depends on the set [Omega] where an initial uniform distribution is assigned. For the algebraic automorphism of the torus the limit is proved to exist and to have the same value for almost all initial sets [Omega] in the subfamily of parallelograms. Numerical results show that it has the same value for arbitrary polygons [Omega] and for arbitrary moments. 13 refs., 3 figs.
Linear Parabolic Maps on the Torus
Zyczkowski, K; Zyczkowski, Karol; Nishikawa, Takashi
1999-01-01
We investigate linear parabolic maps on the torus. In a generic case these maps are non-invertible and discontinuous. Although the metric entropy of these systems is equal to zero, their dynamics is non-trivial due to folding of the image of the unit square into the torus. We study the structure of the maximal invariant set, and in a generic case we prove the sensitive dependence on the initial conditions. We study the decay of correlations and the diffusion in the corresponding system on the plane. We also demonstrate how the rationality of the real numbers defining the map influences the dynamical properties of the system.
Equilibrium-torus bifurcation in nonsmooth systems
DEFF Research Database (Denmark)
Zhusubahyev, Z.T.; Mosekilde, Erik
2008-01-01
Considering a set of two coupled nonautonomous differential equations with discontinuous right-hand sides describing the behavior of a DC/DC power converter, we discuss a border-collision bifurcation that can lead to the birth of a two-dimensional invariant torus from a stable node equilibrium...... linear approximation to our system in the neighbourhood of the border. We determine the functional relationships between the parameters of the normal form map and the actual system and illustrate how the normal form theory can predict the bifurcation behaviour along the border-collision equilibrium......-torus bifurcation curve....
On Chebyshev polynomials and torus knots
Gavrilik, A. M.; Pavlyuk, A. M.
2009-01-01
In this work we demonstrate that the q-numbers and their two-parameter generalization, the q,p-numbers, can be used to obtain some polynomial invariants for torus knots and links. First, we show that the q-numbers, which are closely connected with the Chebyshev polynomials, can also be related with the Alexander polynomials for the class T(s,2) of torus knots, s being an odd integer, and used for finding the corresponding skein relation. Then, we develop this procedure in order to obtain, wit...
The Lack of Torus Emission from BL Lacertae Objects: An Infrared View of Unification with WISE
Plotkin, Richard M; Brandt, W N; Markoff, Sera; Shemmer, Ohad; Wu, Jianfeng
2011-01-01
We use data from the Wide-Field Infrared Survey Explorer (WISE) to perform a statistical study on the mid-infrared (IR) properties of a large number ($\\sim10^2$) of BL Lac objects --- low-luminosity Active Galactic Nuclei (AGN) with a jet beamed toward the Earth. As expected, many BL Lac objects are so highly beamed that their jet synchrotron emission dominates their IR spectral energy distributions. In other BL Lac objects, however, the jet is not strong enough to completely dilute the rest of the AGN emission. We do not see observational signatures of the dusty torus from these weakly beamed BL Lac objects. The lack of observable torus emission is consistent with suggestions that BL Lac objects are fed by radiatively inefficient accretion disks. Implications for the "nature vs. nurture" debate for FR I and FR II radio galaxies are briefly discussed. Our study supports the notion that, beyond orientation, accretion rate plays an important role in AGN unification.
Directory of Open Access Journals (Sweden)
Manuel Ramon Osorio Castillo
2014-06-01
Full Text Available ResumenLos huesos maxilares no son ajenos a las patologías que se pueden presentar en el sistema esquelético. Algunas de esas condiciones y patologías son singulares por sus características clínicas, su distribución y prevalencia. Los torus palatinos, los torus mandibulares (TM y las exostosis de los maxilares son un claro ejemplo de ellos. Hasta la presente existen ideas especulativas acerca de su etiopatogenia, de los factores asociados, de su incidencia y prevalencia, de su necesidad de tratamiento, lo que puede crear confusión entre los clínicos tanto en diagnóstico como en el manejo.El torus como tumor óseo benigno puede localizarse en el maxilar a nivel del paladar, o en la mandíbula a nivel de las tablas internas; o puede aparecer en cualquier parte del esqueleto. El TM es una exostosis o crecimiento óseo en la superficie lingual de la mandíbula. Este crecimiento ocurre generalmente cerca de la línea milohioidea, opuesto a los premolares, pero se puede extender del canino al primer molar. La mucosa que los recubre tiende a ser fina y no tolera por lo general las fuerzas de las prótesis que se colocan encima de ellos. La incidencia del torus de la mandíbula es baja en el 6% a 12.5% entre caucásicos y en los habitantes de la llanura africana. De manera contraria, algunos autores reportan una prevalencia mucho más elevada en la Costa Atlántica Colombiana.Se presenta el caso de un paciente con torus mandibulares bilaterales, con muchos años de crecimiento, hasta que por situaciones tanto fonéticas como de ulceraciones repetitivas decidió someterse al acto quirúrgico de forma bilateral. Se presentan algunas consideraciones para el manejo de esta. (Duazary 2008; 111-114AbstractThe jawbone is not a strange to the pathologies that can occur in the skeletal system. Some of these terms and conditions are unique for their clinical features, distribution and prevalence. The torus palate, jawbone torus (TM in spanish and
Three-dimensional radiative transfer modeling of AGN dusty tori as a clumpy two-phase medium
Stalevski, Marko; Baes, Maarten; Nakos, Theodoros; Popovic, Luka C
2011-01-01
We investigate the emission of active galactic nuclei (AGN) dusty tori in the infrared domain. Following theoretical predictions coming from hydrodynamical simulations, we model the dusty torus as a 3D two-phase medium with high-density clumps and low-density medium filling the space between the clumps. Spectral energy distributions (SED) and images of the torus at different wavelengths are obtained using 3D Monte Carlo radiative transfer code SKIRT. Our approach of generating clumpy structure allows us to model tori with single clumps, complex structures of merged clumps or interconnected sponge-like structure. A corresponding set of clumps-only models and models with smooth dust distribution is calculated for comparison. We found that dust distribution, optical depth, clump size and their actual arrangement in the innermost region, all have an impact on the shape of near- and mid-infrared SED. The 10 micron silicate feature can be suppressed for some parameters, but models with smooth dust distribution are ...
Dorodnitsyn, A.; Bisnovatyi-Kogan. G. S.; Kallman, T.
2011-01-01
We construct a radiation-hydrodynamics model for the obscuring toroidal structure in active galactic nuclei. In this model the obscuration is produced at parsec scale by a dense, dusty wind which is supported by infrared radiation pressure on dust grains. To find the distribution of radiation pressure, we numerically solve the 2D radiation transfer problem in a flux limited diffusion approximation. We iteratively couple the solution with calculations of stationary 1D models for the wind, and obtain the z-component of the velocity. Our results demonstrate that for AGN luminosities greater than 0.1 L(sub edd) external illumination can support a geometrically thick obscuration via outflows driven by infrared radiation pressure. The terminal velocity of marginally Compton-thin models (0.2 AGN torus problem and AGN unification models. Such winds can also provide an important channel for AGN feedback.
Surgical management of palatine Torus - case series
Directory of Open Access Journals (Sweden)
Thaís Sumie Nozu Imada
Full Text Available INTRODUCTION: Torus palatinus is a specific name to identify exostoses developed in the hard palate along the median palatine suture. Despite of not being a pathological condition, its presence requires attention and knowledge regarding its management. Surgical removal of exostoses is indicated when the patient frequently traumatizes the area of palatine torus during mastication and speech or when it is necessary for the rehabilitation of the upper arcade with complete dentures. OBJECTIVE: The aim of this article is to present three cases of Torus palatinus and to discuss the management of them. CASE REPORT: In the first case, a 57-year-old Caucasian man sought oral rehabilitation of his edentulous maxilla but presented a hard nodules in the hard palate; in the second case, a 40-year-old Caucasian woman was referred for frequent trauma of palatal mucosa during mastication, aesthetic complaint, and discomfort caused by the trauma of her tongue in this area; and in the third case, a 45-year-old Caucasian woman presented with a lesion on the palate that caused difficulty swallowing. When the Torus palatinus was impairing the basic physiological functions of the patients, all cases were surgically treated, improving the patients' quality of life. FINAL CONSIDERATION: The dentist should be properly prepared to choose the best from among the existing surgical approaches for each individual lesion in order to improve the results and avoid possible complications.
Resistive Drift Waves in a Bumpy Torus
Energy Technology Data Exchange (ETDEWEB)
J.L.V. Lewandowski
2004-01-12
A computational study of resistive drift waves in the edge plasma of a bumpy torus is presented. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.
Refined large N duality for torus knots
DEFF Research Database (Denmark)
Nawata, Satoshi; Kameyama, Masaya
We formulate large N duality of U(N) refined Chern-Simons theory with a torus knot/link in S³. By studying refined BPS states in M-theory, we provide the explicit form of low-energy effective actions of Type IIA string theory with D4-branes on the Ω-background. This form enables us to relate...
Large N reduction on a twisted torus
González-Arroyo, A; Neuberger, H
2005-01-01
We consider SU(N) lattice gauge theory at infinite N defined on a torus with a CP invariant twist. Massless fermions are incorporated in an elegant way, while keeping them quenched. We present some numerical results which suggest that twisting can make numerical simulations of planar QCD more efficient.
Magnetostatics of the uniformly polarized torus
DEFF Research Database (Denmark)
Beleggia, Marco; De Graef, Marc; Millev, Yonko
2009-01-01
We provide an exhaustive description of the magnetostatics of the uniformly polarized torus and its derivative self-intersecting (spindle) shapes. In the process, two complementary approaches have been implemented, position-space analysis of the Laplace equation with inhomogeneous boundary...
Induction effects of torus knots and unknots
Oberti, Chiara; Ricca, Renzo L.
2017-09-01
Geometric and topological aspects associated with induction effects of field lines in the shape of torus knots/unknots are examined and discussed in detail. Knots are assumed to lie on a mathematical torus of circular cross-section and are parametrized by standard equations. The induced field is computed by direct integration of the Biot-Savart law. Field line patterns of the induced field are obtained and several properties are examined for a large family of knots/unknots up to 51 crossings. The intensity of the induced field at the origin of the reference system (center of the torus) is found to depend linearly on the number of toroidal coils and reaches maximum values near the boundary of the mathematical torus. New analytical estimates and bounds on energy and helicity are established in terms of winding number and minimum crossing number. These results find useful applications in several contexts when the source field is either vorticity, electric current or magnetic field, from vortex dynamics to astrophysics and plasma physics, where highly braided magnetic fields and currents are present.
Institute of Scientific and Technical Information of China (English)
Chong Qing CHENG
2011-01-01
Given an integrable Hamiltonian ho with n-degrees of freedom and a Diophantine frequency w, then, arbitrarily close to ho in the Cr topology with r ＜ 2n, there exists an analytical Hamiltonian h∈ with no KAM torus of rotation vector w. In contrast with it, KAM tori exist if perturbations are small in Cr topology with r ＞ 2n.
Vertex Algebra Sheaf Structure on Torus
Institute of Scientific and Technical Information of China (English)
SUN Yuan-yuan
2016-01-01
In this paper, we first give a 1-1 corresponds between torus C/Λand cubic curve C in P2C. As complex manifold, they are isomorphic, therefore we can treat C/Λas a variety and construction a vertex algebra sheaf on it.
Electrostatic confinement in a bumpy torus
Energy Technology Data Exchange (ETDEWEB)
El Nadi, A.M.
1984-11-01
In a closed-field-line device such as a bumpy torus, the combined E x B and del B drifts lead to charge separation that is balanced by the ion polarization drift. In this work, we determine self-consistent potential and density profiles and the condition for electric island formation.
Refined large N duality for torus knots
DEFF Research Database (Denmark)
Nawata, Satoshi; Kameyama, Masaya
We formulate large N duality of U(N) refined Chern-Simons theory with a torus knot/link in S³. By studying refined BPS states in M-theory, we provide the explicit form of low-energy effective actions of Type IIA string theory with D4-branes on the Ω-background. This form enables us to relate...
Benford, Dominic J.
2010-01-01
The Wide-field Infrared Survey is a medium class Explorer mission that was launched onl4Dec 2009. WISE should detect hundreds of millions of stars and galaxies, including millions of ULIRGS and QSOs; hundreds of thousands of asteroids; and hundreds of cold brown dwarfs. The telescope cover was ejected on 29 Dec 2009 and the all-sky survey started on 14 Jan 2010. WISE takes more the 7000 framesets per day, with each frameset covering 0.6 square degrees in four bands centered at 3.4, 4.6, 12 and 22 microns. WISE is well-suited to the discovery of brown dwarfs, ultraluminous infrared galaxies, and near-Earth objects. With an angular resolution of 6 arcsecouds at 12 microns, a 5(sigma) point-source sensitivity of around 1 mJy at 12 microns and 6 mJy at 22 microns, and coverage of over 99% of the sky, WISE also provides a powerful database for the study of the dusty ISM in our own galaxy. A preliminary release of WISE data will be made available to the community 6 months after the end of the cryogenic survey, or about May 2011. The final data release will be 11 months later, about April 2012.
Dusty winds II. Observational Implications
Ivezic, Zeljko
2010-01-01
We compare observations of AGB stars and predictions of the Elitzur & Ivezic (2001) steady-state radiatively driven dusty wind model. The model results are described by a set of similarity functions of a single independent variable, and imply general scaling relations among the system parameters. We find that the model properly reproduces various correlations among the observed quantities and demonstrate that dust drift through the gas has a major impact on the structure of most winds. From data for nearby oxygen-rich and carbon-rich mass-losing stars we find that (1) the dispersion in grain properties within each group is rather small; (2) both the dust cross-section per gas particle and the dust-to-gas mass ratio are similar for the two samples even though the stellar atmospheres and grain properties are very different; (3) the dust abundance in both outflows is significantly below the Galactic average, indicating that most of the Galactic dust is not stardust - contrary to popular belief, but in suppor...
The Lunar dusty plasmas -levitation and transport.
Atamaniuk, Barbara; Rothkaehl, Hanna
Lunar dust can exhibit unusual behavior -due to electron photoemission via solar-UV radiation the lunar surface represents a complex plasma -"dusty plasma". The dust grains and lunar surface are electrostatically charged by the Moon's interaction with the local plasma environ-ment and the photoemission of electrons due to solar UV and X-rays. This effect causes the like-charged surface and dust particles to repel each other, and creates a near-surface electric field. Lunar dust must be treated as a dusty plasma. Using analytic (kinetic (Vlasov) and magnetohydrodynamic theory ) and numerical modeling we show physical processes related to levitation and transport dusty plasma on the Moon. These dust grains could affect the lunar environment for radio wave and plasma diagnostics and interfere with exploration activities. References: 1. Wilson T.L. (1992), in Analysis of Interplanetary Dust, M. Zolensky et al. AIP Conf.Proc. 310, 33-44 (AIP, NY), 2.Wilson T.L."LUNAR DUST AND DUSTY PLASMA PHYSICS".40th Lunar and Planetary Science Conference (2009), 3. Grün E., et al.(1993),Nature 363, 144. 4. Morfill G. and Grün E.(1979), Planet. Space Sci.. 27, 1269, 1283, 5. Manka R. and Michel F. (1971), Proc. 2nd Lun. Sci. Conf. 2, 1717 (MIT Press, Cambridge). 6. Manka R. et al.(1973), Lun. Sci.-III, 504. 7. Barbara Atamaniuk "Kinetic Description of Localized Plasma Structure in Dusty Plasmas". Czechoslovak Journal of Physics Vol.54 C 2004
AGN Dusty Tori as a Clumpy Two-Phase Medium: The 10 Micron Silicate Feature
Stalevski, Marko; Baes, Maarten; Nakos, Theodoros; Popovic, Luka C
2011-01-01
We investigated the emission of active galactic nuclei dusty tori in the infrared domain, with a focus on the 10 micron silicate feature. We modeled the dusty torus as a clumpy two-phase medium with high-density clumps and a low-density medium filling the space between the clumps. We employed a three-dimensional radiative transfer code to obtain spectral energy distributions and images of tori at different wavelengths. We calculated a grid of models for different parameters and analyzed the influence of these parameters on the shape of the mid-infrared emission. A corresponding set of clumps-only models and models with a smooth dust distribution is calculated for comparison. We found that the dust distribution, the optical depth and a random arrangement of clumps in the innermost region, all have an impact on the shape and strength of the silicate feature. The 10 micron silicate feature can be suppressed for some parameters, but models with smooth dust distribution are also able to produce a wide range of the...
The Sun's dusty interstellar environment
Sterken, Veerle
2016-07-01
The Sun's dusty interstellar environment Interstellar dust from our immediate interstellar neighborhood travels through the solar system at speeds of ca. 26 km/s: the relative speed of the solar system with respect to the local interstellar cloud. On its way, its trajectories are altered by several forces like the solar radiation pressure force and Lorentz force. The latter is due to the charged dust particles that fly through the interplanetary magnetic field. These trajectories differ per particle type and size and lead to varying fluxes and directions of the flow inside of the solar system that depend on location but also on phase in the solar cycle. Hence, these fluxes and directions depend strongly on the configuration of the inner regions and outer regions of the heliosphere. Several missions have measured this dust in the solar system directly. The Ulysses dust detector data encompasses 16 years of intestellar dust fluxes and approximate directions, Stardust captured returned to Earth a few of these particles sucessfully, and finally the Cassini dust detector allowed for compositional information to be obtained from the impacts on the instrument. In this talk, we give an overview of the current status of interstellar dust research through the measurements made inside of the solar system, and we put them in perspective to the knowledge obtained from more classical astronomical means. In special, we focus on the interaction of the dust with the interplanetary magnetic field, and on what we learn about the dust (and the fields) by comparing the available dust data to computer simulations of dust trajectories. Finally, we synthesize the different methods of observation, their results, and give a preview on new research opportunities in the coming year(s).
Size selective dustiness and exposure; simulated workplace comparisons
Brouwer, D.H.; Links, I.H.M.; Vreede, S.A.F.de; Christopher, Y.
2006-01-01
A simulated workplace study was conducted to investigate the relation between inhalation exposure and dustiness determined with a rotating drum dustiness tester. Three powders were used in the study, i.e. magnesium stearate, representing a very dusty powder, and aluminium oxide and calcium
Size selective dustiness and exposure; simulated workplace comparisons
Brouwer, D.H.; Links, I.H.M.; Vreede, S.A.F.de; Christopher, Y.
2006-01-01
A simulated workplace study was conducted to investigate the relation between inhalation exposure and dustiness determined with a rotating drum dustiness tester. Three powders were used in the study, i.e. magnesium stearate, representing a very dusty powder, and aluminium oxide and calcium carbonate
TORUS: Theory of Reactions for Unstable iSotopes - Year 1 Continuation and Progress Report
Energy Technology Data Exchange (ETDEWEB)
Arbanas, G; Elster, C; Escher, J; Mukhamedzhanov, A; Nunes, F; Thompson, I J
2011-02-24
The TORUS collaboration derives its name from the research it focuses on, namely the Theory of Reactions for Unstable iSotopes. It is a Topical Collaboration in Nuclear Theory, and funded by the Nuclear Theory Division of the Office of Nuclear Physics in the Office of Science of the Department of Energy. The funding started on June 1, 2010, it will have been running for nine months by the date of submission of this Annual Continuation and Progress Report on March 1, 2011. The extent of funding was reduced from the original application, and now supports one postdoctoral researcher for the years 1 through 3. The collaboration brings together as Principal Investigators a large fraction of the nuclear reaction theorists currently active within the USA. The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. This multi-institution collaborative effort is directly relevant to three areas of interest: the properties of nuclei far from stability; microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory.
On Chebyshev polynomials and torus knots
Gavrilik, A M
2009-01-01
In this work we demonstrate that the q-numbers and their two-parameter generalization, the q,p-numbers, can be used to obtain some polynomial invariants for torus knots and links. First, we show that the q-numbers, which are closely connected with the Chebyshev polynomials, can also be related with the Alexander polynomials for the class T(s,2) of torus knots, s being an odd integer, and used for finding the corresponding skein relation. Then, we develop this procedure in order to obtain, with the help of q,p-numbers, the generalized two-variable Alexander polynomials, and prove their direct connection with the HOMFLY polynomials and the skein relation of the latter.
Exploring Torus Universes in Causal Dynamical Triangulations
Budd, T G
2013-01-01
Motivated by the search for new observables in nonperturbative quantum gravity, we consider Causal Dynamical Triangulations (CDT) in 2+1 dimensions with the spatial topology of a torus. This system is of particular interest, because one can study not only the global scale factor, but also global shape variables in the presence of arbitrary quantum fluctuations of the geometry. Our initial investigation focusses on the dynamics of the scale factor and uncovers a qualitatively new behaviour, which leads us to investigate a novel type of boundary conditions for the path integral. Comparing large-scale features of the emergent quantum geometry in numerical simulations with a classical minisuperspace formulation, we find partial agreement. By measuring the correlation matrix of volume fluctuations we succeed in reconstructing the effective action for the scale factor directly from the simulation data. Apart from setting the stage for the analysis of shape dynamics on the torus, the new set-up highlights the role o...
Phases of planar QCD on the torus
Narayanan, R; Narayanan, Rajamani; Neuberger, Herbert
2005-01-01
At infinite N, continuum Euclidean SU(N) gauge theory defined on a symmetrical four torus has a rich phase structure with phases where the finite volume system behaves as if it had infinite extent in some or all of the directions. In addition, fermions are automatically quenched, so planar QCD should be cheaper to solve numerically that full QCD. Large N is a relatively unexplored and worthwhile direction of research in lattice field theory.
Energy cascades for NLS on the torus
Carles, Remi
2010-01-01
We consider the nonlinear Schrodinger equation with cubic (focusing or defocusing) nonlinearity on the multidimensional torus. For special small initial data containing only five modes, we exhibit a countable set of time layers in which arbitrarily large modes are created. The proof relies on a reduction to multiphase weakly nonlinear geometric optics, and on the study of a particular two-dimensional discrete dynamical system.
Torus Knots and the Topological Vertex
Jockers, Hans; Soroush, Masoud
2012-01-01
We propose a class of toric Lagrangian A-branes on the resolved conifold that is suitable to describe torus knots on S^3. The key role is played by the SL(2,Z) transformation, which generates a general torus knot from the unknot. Applying the topological vertex to the proposed A-branes, we rederive the colored HOMFLY polynomials for torus knots, in agreement with the Rosso and Jones formula. We show that our A-model construction is mirror symmetric to the B-model analysis of Brini, Eynard and Marino. Comparing to the recent proposal by Aganagic and Vafa for knots on S^3, we demonstrate that the disk amplitude of the A-brane associated to any knot is sufficient to reconstruct the entire B-model spectral curve. Finally, the construction of toric Lagrangian A-branes is generalized to other local toric Calabi-Yau geometries, which paves the road to study knots in other three-manifolds such as lens spaces.
Marin, F.; Goosmann, R. W.; Petrucci, P.-O.
2016-06-01
Context. Obscuring circumnuclear dust is a well-established constituent of active galactic nuclei (AGN). Traditionally referred to as the receding dusty torus, its inner radius and angular extension should depend on the photo-ionizing luminosity of the central source. Aims: We quantify the expected time-dependent near-infrared (NIR), optical, ultraviolet (UV) and X-ray polarization of a receding dusty torus as a function of the variable X-ray flux level and spectral shape. Methods: Using a Monte Carlo approach, we simulate the radiative transfer between the multiple components of an AGN adopting model constraints from the bright Seyfert galaxy NGC 4151. We compare our model results to the observed NIR to UV polarization of the source and predict its X-ray polarization. Results: We find that the 2-8 keV polarization fraction of a standard AGN model varies from less then a few percent along polar viewing angles up to tens of percent at equatorial inclinations. At viewing angles around the type-1/type-2 transition, there is a different X-ray polarization variability in a static or a receding torus scenario. In the former case, the expected 2-8 keV polarization of NGC 4151 is found to be 1.21% ± 0.34% with a constant polarization position angle, while in the latter scenario it varies from 0.1% to 6% depending on the photon index of the primary radiation. Additionally, an orthogonal rotation of the polarization position angle with photon energy appears for very soft primary spectra. Conclusions: Future X-ray polarimetry missions will be able to test whether the receding model is valid for Seyfert galaxies seen at a viewing angle close to the torus horizon. The overall stability of the polarization position angle for photon indexes softer than Γ = 1.5 ensures that reliable measurements of X-ray polarization are possible. We derive a long-term observational strategy for NGC 4151 assuming observations with a small to medium-sized X-ray polarimetry satellite.
A new equilibrium torus solution and GRMHD initial conditions
Penna, Robert F; Narayan, Ramesh
2013-01-01
General relativistic magnetohydrodynamic (GRMHD) simulations are providing influential models for black hole spin measurements, gamma ray bursts, and supermassive black hole feedback. Many of these simulations use the same initial condition: a rotating torus of fluid in hydrostatic equilibrium. A persistent concern is that simulation results sometimes depend on arbitrary features of the initial torus. For example, the Bernoulli parameter (which is related to outflows), appears to be controlled by the Bernoulli parameter of the initial torus. In this paper, we give a new equilibrium torus solution and describe two applications for the future. First, it can be used as a more physical initial condition for GRMHD simulations than earlier torus solutions. Second, it can be used in conjunction with earlier torus solutions to isolate the simulation results that depend on initial conditions. We assume axisymmetry, an ideal gas equation of state, constant entropy, and ignore self-gravity. We fix an angular momentum di...
Studying uniform thickness II: Transversely nonsimple iterated torus knots
DEFF Research Database (Denmark)
LaFountain, Douglas
2011-01-01
We prove that an iterated torus knot type in the standard contact 3-sphere fails the uniform thickness property (UTP) if and only if it is formed from repeated positive cablings, which is precisely when an iterated torus knot supports the standard contact structure. This is the first complete UTP...... classification for a large class of knots. We also show that all iterated torus knots that fail the UTP support cabling knot types that are transversely non-simple....
Circuit-Switched Gossiping in the 3-Dimensional Torus Networks
Delmas, Olivier; Pérennes, Stéphane
1996-01-01
In this paper we describe, in the case of short messages, an efficient gossiping algorithm for 3-dimensional torus networks (wrap-around or toroidal meshes) that uses synchronous circuit-switched routing. The algorithm is based on a recursive decomposition of a torus. The algorithm requires an optimal number of rounds and a quasi-optimal number of intermediate switch settings to gossip in an $7^i \\times 7^i \\times 7^i$ torus.
Dispersionless and multicomponent BKP hierarchies with quantum torus symmetries
Li, Chuanzhong
2017-09-01
In this article, we will construct the additional perturbative quantum torus symmetry of the dispersionless BKP hierarchy based on the W∞ infinite dimensional Lie symmetry. These results show that the complete quantum torus symmetry is broken from the BKP hierarchy to its dispersionless hierarchies. Further a series of additional flows of the multicomponent BKP hierarchy will be defined and these flows constitute an N-folds direct product of the positive half of the quantum torus symmetries.
Finite dust clusters in dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Melzer, A; Buttenschoen, B; Miksch, T; Passvogel, M [Institute of Physics, Ernst-Moritz-Arndt-Universitaet Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Block, D; Arp, O; Piel, A, E-mail: melzer@physik.uni-greifswald.d [IEAP, Christian-Albrechts-Universitaet Kiel, Olshausenstr. 40-60, 24098 Kiel (Germany)
2010-12-15
We review recent experiments on the formation of finite systems of charged microspheres in dusty plasmas. There, finite arrangements of these dust clusters can be studied in different geometries ranging from 1D to 3D. The structure and the mode dynamics in these systems will be discussed.
Er:YAG Laser: A New Technical Approach to Remove Torus Palatinus and Torus Mandibularis
Directory of Open Access Journals (Sweden)
J. P. Rocca
2012-01-01
Full Text Available Objective. The aim of this study was to assess the ability of Er:YAG laser to remove by excision torus mandibularis and to smooth torus palatinus exostosis. Materials and Methods. Torus mandibularis (TM and torus palatinus (TP were surgically eliminated via the Er:YAG laser using the following parameters: TM: output power ranging from 500 to 1000 mJ, frequency from 20 to 30 Hz, sapphire tips (diameter 0.8 mm, air-water spray (ratio 5/5, pulse duration 150 μsec, fluence ranging from 99592 J/cm2 to 199044,586 J/cm2. TP: a peeling technique was used to eliminate TP, as excision by slicing being impossible here. Results. TM: excision was obtained after 12730 pulses. TP: smoothing technique took more time compared with excision. Once peeling was considered to be accomplished, the use of a surgical rasp was necessary to eliminate bone spicules that could delay the wound to heal in good conditions. Conclusion. Er:YAG excision (TM or Er:YAG peeling (TP are safe clinical techniques easy to practice even if the time required for excision or surface smoothing is more than the time required with bony burs and high speed instruments.
Er:YAG Laser: A New Technical Approach to Remove Torus Palatinus and Torus Mandibularis
Rocca, J. P.; Raybaud, H.; Merigo, E.; Vescovi, P.; Fornaini, C.
2012-01-01
Objective. The aim of this study was to assess the ability of Er:YAG laser to remove by excision torus mandibularis and to smooth torus palatinus exostosis. Materials and Methods. Torus mandibularis (TM) and torus palatinus (TP) were surgically eliminated via the Er:YAG laser using the following parameters: TM: output power ranging from 500 to 1000 mJ, frequency from 20 to 30 Hz, sapphire tips (diameter 0.8 mm), air-water spray (ratio 5/5), pulse duration 150 μsec, fluence ranging from 99592 J/cm2 to 199044,586 J/cm2. TP: a peeling technique was used to eliminate TP, as excision by slicing being impossible here. Results. TM: excision was obtained after 12730 pulses. TP: smoothing technique took more time compared with excision. Once peeling was considered to be accomplished, the use of a surgical rasp was necessary to eliminate bone spicules that could delay the wound to heal in good conditions. Conclusion. Er:YAG excision (TM) or Er:YAG peeling (TP) are safe clinical techniques easy to practice even if the time required for excision or surface smoothing is more than the time required with bony burs and high speed instruments. PMID:22792500
A principle for ideal torus knots
DEFF Research Database (Denmark)
Olsen, Kasper Wibeck; Bohr, Jakob
2013-01-01
Using bent-helix embeddings, we investigate simple and knotted torus windings that are made of tubes of finite thickness. Knots which have the shortest rope length are often denoted as ideal structures. Conventionally, the ideal structures are found by rope shortening routines. It is shown...... that alternatively they can be directly determined as maximally twisted structures. In many cases these structures are also structures with zero strain-twist coupling, i.e. structures that neither rotate one or the other way under strain. We use this principle to implement rapid numerical calculations of the ideal...
Torus knots and the rational DAHA
Gorsky, Eugene; Rasmussen, Jacob; Shende, Vivek
2012-01-01
We conjecturally extract the triply graded Khovanov-Rozansky homology of the (m, n) torus knot from the unique finite dimensional simple representation of the rational DAHA of type A, rank n - 1, and central character m/n. The conjectural differentials of Gukov, Dunfield and the third author receive an explicit algebraic expression in this picture, yielding a prescription for the doubly graded Khovanov-Rozansky homologies. We match our conjecture to previous conjectures of the first author relating knot homology to q, t-Catalan numbers, and of the last three authors relating knot homology to Hilbert schemes on singular curves.
A METHOD FOR STIFFNESS MATRIX OF TRIANGULAR TORUS ELEMENT
Directory of Open Access Journals (Sweden)
Durmuş GÜNAY
1996-01-01
Full Text Available The matrices of constants for the stiffness matrices of triangular torus elements family are generated on computer by using the expression given in literature. After the matrices are generated once, it is easy to obtain the stiffness matrices for all member of family of triangular torus elements without need for numerical integration.
Studying uniform thickness II: Transversely nonsimple iterated torus knots
DEFF Research Database (Denmark)
LaFountain, Douglas
2011-01-01
We prove that an iterated torus knot type in the standard contact 3-sphere fails the uniform thickness property (UTP) if and only if it is formed from repeated positive cablings, which is precisely when an iterated torus knot supports the standard contact structure. This is the first complete UTP...
Direct detection of the Enceladus water torus with Herschel
Hartogh, P.; Lellouch, E.; Moreno, R.; Bockelee-Morvan, D.; Biver, N.; Cassidy, T.; Rengel, M.; Jarchow, C.; Cavalie, T.; Crovisier, J.; Helmich, F. P.; Kidger, M.
Cryovolcanic activity near the south pole of Saturn's moon Enceladus produces plumes of H2O-dominated gases and ice particles, which escape and populate a torus-shaped cloud. Using submillimeter spectroscopy with Herschel, we report the direct detection of the Enceladus water vapor torus in four
Direct detection of the Enceladus water torus with Herschel
Hartogh, P.; Lellouch, E.; Moreno, R.; Bockelee-Morvan, D.; Biver, N.; Cassidy, T.; Rengel, M.; Jarchow, C.; Cavalie, T.; Crovisier, J.; Helmich, F. P.; Kidger, M.
2011-01-01
Cryovolcanic activity near the south pole of Saturn's moon Enceladus produces plumes of H2O-dominated gases and ice particles, which escape and populate a torus-shaped cloud. Using submillimeter spectroscopy with Herschel, we report the direct detection of the Enceladus water vapor torus in four rot
On some Closed Magnetic Curves on a 3-torus
Energy Technology Data Exchange (ETDEWEB)
Munteanu, Marian Ioan, E-mail: marian.ioan.munteanu@gmail.com [Alexandru Ioan Cuza University of Iaşi, Faculty of Mathematics (Romania); Nistor, Ana Irina, E-mail: ana.irina.nistor@gmail.com [Gh. Asachi Technical University of Iaşi, Department of Mathematics and Informatics (Romania)
2017-06-15
We consider two magnetic fields on the 3-torus obtained from two different contact forms on the Euclidean 3-space and we study when their corresponding normal magnetic curves are closed. We obtain periodicity conditions analogues to those for the closed geodesics on the torus.
Recent Progress on Spherical Torus Research
Energy Technology Data Exchange (ETDEWEB)
Ono, Masayuki [PPPL; Kaita, Robert [PPPL
2014-01-01
The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.
Torus hyperplasia of the pyloric antrum.
Kim, Chi-Hun; Han, Hye Seung; Lee, Sun-Young; Kim, Byung Kook; Sung, In-Kyung; Seong, Moo Kyung; Lee, Kyung Yung
2010-01-01
Primary or idiopathic hypertrophy of the pyloric muscle in adult, so called torus hyperplasia, is an infrequent but an established entity. It is caused by a circular muscle hypertrophy affecting the lesser curvature near the pylorus. Since most of the lesions are difficult to differentiate from tumor, distal gastrectomy is usually preformed to rule out most causes of pyloric lesions including neoplastic ones through a pathological study. A 56-yr-old man with a family history of gastric cancer presented with abdominal discomfort of 1 month duration. Upper gastrointestinal endoscopy showed a 1.0 cm sized irregular submucosal lesion proximal to the pylorus to the distal antrum on the lesser curvature. On colonoscopy examination, a 1.5 cm sized protruding mass was noticed on the appendiceal orifice. Gastrectomy and cecectomy were done, and histological section revealed marked hypertrophy of the distal circular pyloric musculature and an appendiceal mucocele. To the best of our knowledge, this is the first case of torus hyperplasia with appendiceal mucocele which is found incidentally.
Arithmetic functions in torus and tree networks
Bhanot, Gyan; Blumrich, Matthias A.; Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard D.; Vranas, Pavlos M.
2007-12-25
Methods and systems for performing arithmetic functions. In accordance with a first aspect of the invention, methods and apparatus are provided, working in conjunction of software algorithms and hardware implementation of class network routing, to achieve a very significant reduction in the time required for global arithmetic operation on the torus. Therefore, it leads to greater scalability of applications running on large parallel machines. The invention involves three steps in improving the efficiency and accuracy of global operations: (1) Ensuring, when necessary, that all the nodes do the global operation on the data in the same order and so obtain a unique answer, independent of roundoff error; (2) Using the topology of the torus to minimize the number of hops and the bidirectional capabilities of the network to reduce the number of time steps in the data transfer operation to an absolute minimum; and (3) Using class function routing to reduce latency in the data transfer. With the method of this invention, every single element is injected into the network only once and it will be stored and forwarded without any further software overhead. In accordance with a second aspect of the invention, methods and systems are provided to efficiently implement global arithmetic operations on a network that supports the global combining operations. The latency of doing such global operations are greatly reduced by using these methods.
Holographic torus entanglement and its RG flow
Bueno, Pablo
2016-01-01
We study the universal contributions to the entanglement entropy (EE) of 2+1d and 3+1d holographic conformal field theories (CFTs) on topologically non-trivial manifolds, focusing on tori. The holographic bulk corresponds to AdS-soliton geometries. We characterize the properties of these regulator-independent EE terms as a function of both the size of the cylindrical entangling region, and the shape of the torus. In 2+1d, in the simple limit where the torus becomes a thin 1d ring, the EE reduces to a shape-independent constant $2\\gamma$. This is twice the EE obtained by bipartitioning an infinite cylinder into equal halves. We study the RG flow of $\\gamma$ by defining a renormalized EE that 1) is applicable to general QFTs, 2) resolves the failure of the area law subtraction, and 3) is inspired by the F-theorem. We find that the renormalized $\\gamma$ decreases monotonically when the holographic CFT is deformed by a relevant operator for all allowed scaling dimensions. We also discuss the question of non-uniqu...
Saturn in hot water: viscous evolution of the Enceladus torus
Farmer, Alison J
2008-01-01
The detection of outgassing water vapor from Enceladus is one of the great breakthroughs of the Cassini mission. The fate of this water once ionized has been widely studied; here we investigate the effects of purely neutral-neutral interactions within the Enceladus torus. We find that, thanks in part to the polar nature of the water molecule, a cold (~180 K) neutral torus would undergo rapid viscous heating and spread to the extent of the observed hydroxyl cloud, before plasma effects become important. We investigate the physics behind the spreading of the torus, paying particular attention to the competition between heating and rotational line cooling. A steady-state torus model is constructed, and it is demonstrated that the torus will be observable in the millimeter band with the upcoming Herschel satellite. The relative strength of rotational lines could be used to distinguish between physical models for the neutral cloud.
Complex Dynamics Caused by Torus Bifurcation in Power Systems
Institute of Scientific and Technical Information of China (English)
YU Xiaodan; JIA Hongjie; DONG Cun
2006-01-01
Torus bifurcation is a relatively complicated bifurcation caused by a pair of complex conjuployed to reveal the relationship between torus bifurcation and some complex dynamics.Based on theoretical analysis and simulation studies, it is found that torus bifurcation is a typical route to chaos in power system.Some complex dynamics usually occur after a torus bifurcation, such as self-organization, deep bifurcations, exquisite structure, coexistence of chaos and divergence.It is also found that chaos has close relationship with various instability scenarios of power systems.Studies of this paper are helpful to understand the mechanism of torus bifurcation in power system and relationship of chaos and power system instabilities.
Lunar Dust and Dusty Plasma Physics
Wilson, Thomas L.
2009-01-01
In the plasma and radiation environment of space, small dust grains from the Moon s surface can become charged. This has the consequence that their motion is determined by electromagnetic as well as gravitational forces. The result is a plasma-like condition known as "dusty plasmas" with the consequence that lunar dust can migrate and be transported by magnetic, electric, and gravitational fields into places where heavier, neutral debris cannot. Dust on the Moon can exhibit unusual behavior, being accelerated into orbit by electrostatic surface potentials as blow-off dust, or being swept away by moving magnetic fields like the solar wind as pick-up dust. Hence, lunar dust must necessarily be treated as a dusty plasma subject to the physics of magnetohydrodynamics (MHD). A review of this subject has been given before [1], but a synopsis will be presented here to make it more readily available for lunar scientists.
Nonmodal phenomena in differentially rotating dusty plasmas
Poedts, Stefaan; Rogava, Andria D.
2000-10-01
In this paper the foundation is layed for the nonmodal investigation of velocity shear induced phenomena in a differentially rotating flow of a dusty plasma. The simplest case of nonmagnetized flow is considered. It is shown that, together with the innate properties of the dusty plasma, the presence of differential rotation, Coriolis forces, and self-gravity casts a considerable richness on the nonmodal dynamics of linear perturbations in the flow. In particular: (i) dust-acoustic waves acquire the ability to extract energy from the mean flow and (ii) shear-induced, nonperiodic modes of collective plasma behavior-shear-dust-acoustic vortices-are generated. The presence of self-gravity and the nonzero Coriolis parameter (``epicyclic shaking'') makes these collective modes transiently unstable. .
Discrete breathers in hexagonal dusty plasma lattices.
Koukouloyannis, V; Kourakis, I
2009-08-01
The occurrence of single-site or multisite localized vibrational modes, also called discrete breathers, in two-dimensional hexagonal dusty plasma lattices is investigated. The system is described by a Klein-Gordon hexagonal lattice characterized by a negative coupling parameter epsilon in account of its inverse dispersive behavior. A theoretical analysis is performed in order to establish the possibility of existence of single as well as three-site discrete breathers in such systems. The study is complemented by a numerical investigation based on experimentally provided potential forms. This investigation shows that a dusty plasma lattice can support single-site discrete breathers, while three-site in phase breathers could exist if specific conditions, about the intergrain interaction strength, would hold. On the other hand, out of phase and vortex three-site breathers cannot be supported since they are highly unstable.
Izumi, T.; Kohno, K.; Fathi, K.; Hatziminaoglou, E.; Davies, R. I.; Martín, S.; Matsushita, S.; Schinnerer, E.; Espada, D.; Aalto, S.; Onishi, K.; Turner, J. L.; Imanishi, M.; Nakanishi, K.; Meier, D. S.; Wada, K.; Kawakatu, N.; Nakajima, T.
2017-08-01
We used the Atacama Large Millimeter/Submillimeter Array to map the CO(3-2) and the underlying continuum emissions around the type-1 low-luminosity active galactic nucleus (LLAGN; bolometric luminosity ≲ {10}42 erg s-1) of NGC 1097 at ˜10 pc resolution. These observations revealed a detailed cold gas distribution within a ˜100 pc of this LLAGN. In contrast to the luminous Seyfert galaxy NGC 1068, where a ˜7 pc cold molecular torus was recently revealed, a distinctively dense and compact torus is missing in our CO(3-2) integrated intensity map of NGC 1097. Based on the CO(3-2) flux, the gas mass of the torus of NGC 1097 would be a factor of ≳2-3 less than that found for NGC 1068 by using the same CO-to-H2 conversion factor, which implies less active nuclear star formation and/or inflows in NGC 1097. Our dynamical modeling of the CO(3-2) velocity field implies that the cold molecular gas is concentrated in a thin layer as compared to the hot gas traced by the 2.12 μm H2 emission in and around the torus. Furthermore, we suggest that NGC 1097 hosts a geometrically thinner torus than NGC 1068. Although the physical origin of the torus thickness remains unclear, our observations support a theoretical prediction that geometrically thick tori with high opacity will become deficient as AGNs evolve from luminous Seyferts to LLAGNs.
Marin, F; Petrucci, P -O
2016-01-01
Obscuring circumnuclear dust is a well-established constituent of active galactic nuclei (AGN). Traditionally referred to as the receding dusty torus, its inner radius and angular extension should depend on the photo-ionizing luminosity of the central source. Using a Monte Carlo approach, we simulate the radiative transfer between the multiple components of an AGN adopting model constraints from the bright Seyfert galaxy NGC 4151. We compare our model results to the observed near-IR to UV polarization of the source and predict its X-ray polarization. We find that the 2-8 keV polarization fraction of a standard AGN model varies from less then a few percent along polar viewing angles up to tens of percent at equatorial inclinations. At viewing angles around the type-1/type-2 transition the X-ray polarization variability differs between a static or a receding torus scenario. In the former case, the expected 2-8 keV polarization of NGC 4151 is found to be 1.21% +/- 0.34% with a constant polarization position angl...
Properties of the close binary and circumbinary torus of the Red Rectangle
Menshikov, A B; Tuthill, P; Weigelt, G; Yungelson, L R; Men'shchikov, Alexander B.; Schertl, Dieter; Tuthill, Peter; Weigelt, Gerd; Yungelson, Lev R.
2002-01-01
New diffraction-limited speckle images of the Red Rectangle in the wavelength range 2.1--3.3 microns with angular resolutions of 44--68 mas and previous speckle images at 0.7--2.2 microns revealed well-resolved bright bipolar outflow lobes and long X-shaped spikes originating deep inside the outflow cavities. This set of high-resolution images stimulated us to reanalyze all infrared observations of the Red Rectangle using our two-dimensional radiative transfer code. The new detailed modeling, together with estimates of the interstellar extinction in the direction of the Red Rectangle enabled us to more accurately determine one of the key parameters, the distance D=710 pc with model uncertainties of 70 pc, which is twice as far as the commonly used estimate of 330 pc. The central binary is surrounded by a compact, massive (M=1.2 Msun), very dense dusty torus with hydrogen densities reaching n_H=2.5x10^12 cm^-3 (dust-to-gas mass ratio rho_d/rho~0.01). The bright component of the spectroscopic binary HD 44179 is...
Scalar Curvature for the Noncommutative Two Torus
Fathizadeh, Farzad
2011-01-01
We give a local expression for the {\\it scalar curvature} of the noncommutative two torus $ A_{\\theta} = C(\\mathbb{T}_{\\theta}^2)$ equipped with an arbitrary translation invariant complex structure and Weyl factor. This is achieved by evaluating the value of the (analytic continuation of the) {\\it spectral zeta functional} $\\zeta_a(s): = \\text{Trace}(a \\triangle^{-s})$ at $s=0$ as a linear functional in $a \\in C^{\\infty}(\\mathbb{T}_{\\theta}^2)$. A new, purely noncommutative, feature here is the appearance of the {\\it modular automorphism group} from the theory of type III factors and quantum statistical mechanics in the final formula for the curvature. This formula coincides with the formula that was recently obtained independently by Connes and Moscovici in their recent paper.
Torus CLAS12-Superconducting Magnet Quench Analysis
Energy Technology Data Exchange (ETDEWEB)
Kashikhin, V S; Elouadhiri, L; Ghoshal, P K; Kashy, D; Makarov, A; Pastor, O; Quettier, L; Velev, G; Wiseman, M
2014-06-01
The JLAB Torus magnet system consists of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration. These coils are wound with SSC-36 Nb-Ti superconductor and have the peak magnetic field of 3.6 T. The first coil manufacturing based on the JLAB design began at FNAL. The large magnet system dimensions (8 m diameter and 14 MJ of stored energy) dictate the need for quench protection. Each coil is placed in an aluminum case mounted inside a cryostat and cooled by 4.6 K supercritical helium gas flowing through a copper tube attached to the coil ID. The large coil dimensions and small cryostat thickness drove the design to challenging technical solutions, suggesting that Lorentz forces due to transport currents and eddy currents during quench and various failure scenarios are analyzed. The paper covers the magnet system quench analysis using the OPERA3d Quench code.
An FPGA-based Torus Communication Network
Pivanti, Marcello; Simma, Hubert
2010-01-01
We describe the design and FPGA implementation of a 3D torus network (TNW) to provide nearest-neighbor communications between commodity multi-core processors. The aim of this project is to build up tightly interconnected and scalable parallel systems for scientific computing. The design includes the VHDL code to implement on latest FPGA devices a network processor, which can be accessed by the CPU through a PCIe interface and which controls the external PHYs of the physical links. Moreover, a Linux driver and a library implementing custom communication APIs are provided. The TNW has been successfully integrated in two recent parallel machine projects, QPACE and AuroraScience. We describe some details of the porting of the TNW for the AuroraScience system and report performance results.
An FPGA-based torus communication network
Energy Technology Data Exchange (ETDEWEB)
Pivanti, Marcello; Schifano, Sebastiano Fabio [INFN, Ferrara (Italy); Ferrara Univ. (Italy); Simma, Hubert [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC
2011-02-15
We describe the design and FPGA implementation of a 3D torus network (TNW) to provide nearest-neighbor communications between commodity multi-core processors. The aim of this project is to build up tightly interconnected and scalable parallel systems for scientific computing. The design includes the VHDL code to implement on latest FPGA devices a network processor, which can be accessed by the CPU through a PCIe interface and which controls the external PHYs of the physical links. Moreover, a Linux driver and a library implementing custom communication APIs are provided. The TNW has been successfully integrated in two recent parallel machine projects, QPACE and AuroraScience. We describe some details of the porting of the TNW for the AuroraScience system and report performance results. (orig.)
On the Torus Cobordant Cohomology Spheres
Indian Academy of Sciences (India)
Ali Özkurt; Doğan Dönmez
2009-02-01
Let be a compact Lie group. In 1960, P A Smith asked the following question: ``Is it true that for any smooth action of on a homotopy sphere with exactly two fixed points, the tangent -modules at these two points are isomorphic?" A result due to Atiyah and Bott proves that the answer is `yes’ for $\\mathbb{Z}_p$ and it is also known to be the same for connected Lie groups. In this work, we prove that two linear torus actions on $S^n$ which are -cobordant (cobordism in which inclusion of each boundary component induces isomorphisms in $\\mathbb{Z}$-cohomology) must be linearly equivalent. As a corollary, for connected case, we prove a variant of Smith’s question.
Exploring Torus Universes in Causal Dynamical Triangulations
DEFF Research Database (Denmark)
Budd, Timothy George; Loll, R.
2013-01-01
Motivated by the search for new observables in nonperturbative quantum gravity, we consider Causal Dynamical Triangulations (CDT) in 2+1 dimensions with the spatial topology of a torus. This system is of particular interest, because one can study not only the global scale factor, but also global...... shape variables in the presence of arbitrary quantum fluctuations of the geometry. Our initial investigation focusses on the dynamics of the scale factor and uncovers a qualitatively new behaviour, which leads us to investigate a novel type of boundary conditions for the path integral. Comparing large......-scale features of the emergent quantum geometry in numerical simulations with a classical minisuperspace formulation, we find partial agreement. By measuring the correlation matrix of volume fluctuations we succeed in reconstructing the effective action for the scale factor directly from the simulation data...
Acetylation of pea isolate in a torus microreactor.
Legrand, J; Guéguen, J; Berot, S; Popineau, Y; Nouri, L
1997-02-20
Acetylation, which acts on the amino groups of proteins, allows to increase the solubility and the emulsifying properties of pea isolate. Acetylation by acetic anhydride was carried out in a torus microreactor in semibatch and continuous conditions. The mixing characteristics, obtained by a residence time distribution (RTD) method, are the same in batch and continuous processes. The maximum acetylation degree reached by the torus reactor is higher than with the stirred reactor. Torus reactors are more efficient than stirred ones as shown by a conversion efficiency, defined by the quantity of modified lysine groups by consumed acetic anhydride. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 409-414, 1997.
Sahai, Raghvendra; Young, K.; Patel, N. A.; Sanchez Contreras, C.; Morris, M.
2006-01-01
We report high angular resolution (approx.1") CO J=3-2 interferometric mapping using the Submillimeter Array (SMA) of IRAS 22036+5306 (I22036), a bipolar preplanetary nebula (PPN) with knotty jets discovered in our HST snapshot survey of young PPNs. In addition, we have obtained supporting lower resolution (approx.10") CO and 13CO J=1-0 observations with the Owens Valley Radio Observatory (OVRO) interferometer, as well as optical long-slit echelle spectra at the Palomar Observatory. The CO J=3-2 observations show the presence of a very fast (approx.220 km/s), highly collimated, massive (0.03 Solar Mass) bipolar outflow with a very large scalar momentum (about 10(exp 39) g cm/s), and the characteristic spatiokinematic structure of bow shocks at the tips of this outflow. The H(alpha) line shows an absorption feature blueshifted from the systemic velocity by approx.100 km/s, which most likely arises in neutral interface material between the fast outflow and the dense walls of the bipolar lobes at low latitudes. The fast outflow in I22036, as in most PPNs, cannot be driven by radiation pressure. We find an unresolved source of submillimeter (and millimeter-wave) continuum emission in I22036, implying a very substantial mass (0.02-0.04 Solar Mass) of large (radius > or approx.1 mm), cold ( or approx.4 Solar Mass) progenitor in which hot-bottom-burning has occurred.
Explorations of Dusty Debris Disk Geometry
Dennihy, E; Clemens, J C
2016-01-01
As the sample of white dwarfs with signatures of planetary systems has grown, statistical studies have begun to suggest our picture of compact debris disk formation from disrupted planetary bodies is incomplete. Here we present the results of an effort to extend the preferred dust disk model introduced by \\citet{jur03} to include elliptical geometries. We apply this model the observed distribution of fractional infrared luminosities, and explore the difference in preferred parameter spaces for a circular and highly elliptical model on a well-studied dusty white dwarf.
Time of relaxation in dusty plasma model
Timofeev, A. V.
2015-11-01
Dust particles in plasma may have different values of average kinetic energy for vertical and horizontal motion. The partial equilibrium of the subsystems and the relaxation processes leading to this asymmetry are under consideration. A method for the relaxation time estimation in nonideal dusty plasma is suggested. The characteristic relaxation times of vertical and horizontal motion of dust particles in gas discharge are estimated by analytical approach and by analysis of simulation results. These relaxation times for vertical and horizontal subsystems appear to be different. A single hierarchy of relaxation times is proposed.
Jeans stability in collisional quantum dusty magnetoplasmas
Energy Technology Data Exchange (ETDEWEB)
Jamil, M.; Asif, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Mir, Zahid [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Faculty of Engineering and Technology, Superior University, Lahore 54000 (Pakistan); Salimullah, M. [Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh)
2014-09-15
Jeans instability is examined in detail in uniform dusty magnetoplasmas taking care of collisional and non-zero finite thermal effects in addition to the quantum characteristics arising through the Bohm potential and the Fermi degenerate pressure using the quantum hydrodynamic model of plasmas. It is found that the presence of the dust-lower-hybrid wave, collisional effects of plasma species, thermal effects of electrons, and the quantum mechanical effects of electrons have significance over the Jeans instability. Here, we have pointed out a new class of dissipative instability in quantum plasma regime.
A method for estimating optical properties of dusty cloud
Institute of Scientific and Technical Information of China (English)
Tianhe Wang; Jianping Huang
2009-01-01
Based on the scattering properties of nonspherical dust aerosol,a new method is developed for retrieving dust aerosol optical depths of dusty clouds.The dusty clouds are defined as the hybrid system of dust plume and cloud.The new method is based on transmittance measurements from surface-based instruments multi-filter rotating shadowband radiometer(MFRSR)and cloud parameters from lidar measurements.It uses the difference of absorption between dust aerosols and water droplets for distinguishing and estimating the optical properties of dusts and clouds,respectively.This new retrieval method is not sensitive to the retrieval error of cloud properties and the maximum absolute deviations of dust aerosol and total optical depths for thin dusty cloud retrieval algorithm are only 0.056 and 0.1.respectively,for given possible uncertainties.The retrieval error for thick dusty cloud mainly depends on lidar-based total dusty cloud properties.
Dusty plasma as a unique object of plasma physics
Norman, G. E.; Timofeev, A. V.
2016-11-01
The self-consistency and basic openness of dusty plasma, charge fluctuations, high dissipation and other features of dusty plasma system lead to the appearance of a number of unusual and unique properties of dusty plasma. “Anomalous” heating of dusty particles, anisotropy of temperatures and other features, parametric resonance, charge fluctuations and interaction potential are among these unique properties. Study is based on analytical approach and numerical simulation. Mechanisms of “anomalous” heating and energy transfer are proposed. Influence of charge fluctuations on the system properties is discussed. The self-consistent, many-particle, fluctuation and anisotropic interparticle interaction potential is studied for a significant range of gas temperature. These properties are interconnected and necessary for a full description of dusty plasmas physics.
A geometric approach to noncommutative principal torus bundles
DEFF Research Database (Denmark)
Wagner, Stefan
2013-01-01
for noncommutative algebras and say that a dynamical system (A, 핋n,α) is called a noncommutative principal 핋n-bundle, if localization leads to a trivial noncommutative principal 핋n-bundle. We prove that this approach extends the classical theory of principal torus bundles and present a bunch of (nontrivial......A (smooth) dynamical system with transformation group 핋n is a triple (A, 핋n,α), consisting of a unital locally convex algebra A, the n-torus 핋n and a group homomorphism α:핋n→Aut(A), which induces a (smooth) continuous action of 핋n on A. In this paper, we present a new, geometrically oriented...... approach to the noncommutative geometry of principal torus bundles based on such dynamical systems. Our approach is inspired by the classical setting: In fact, after recalling the definition of a trivial noncommutative principal torus bundle, we introduce a convenient (smooth) localization method...
Chern-Simons Invariants of Torus Knots and Links
Stevan, Sébastien
2010-01-01
We compute the vacuum expectation values of torus knot operators in Chern-Simons theory, and we obtain explicit formulae for all classical gauge groups and for arbitrary representations. We reproduce a known formula for the HOMFLY invariants of torus links and we obtain an analogous formula for Kauffman invariants. We also derive a formula for cable knots. We use our results to test a recently proposed conjecture that relates HOMFLY and Kauffman invariants.
Torus as phase space: Weyl quantization, dequantization, and Wigner formalism
Energy Technology Data Exchange (ETDEWEB)
Ligabò, Marilena, E-mail: marilena.ligabo@uniba.it [Dipartimento di Matematica, Università di Bari, I-70125 Bari (Italy)
2016-08-15
The Weyl quantization of classical observables on the torus (as phase space) without regularity assumptions is explicitly computed. The equivalence class of symbols yielding the same Weyl operator is characterized. The Heisenberg equation for the dynamics of general quantum observables is written through the Moyal brackets on the torus and the support of the Wigner transform is characterized. Finally, a dequantization procedure is introduced that applies, for instance, to the Pauli matrices. As a result we obtain the corresponding classical symbols.
Theoretical analysis of a parabolic torus reflector antenna with multibeam
Institute of Scientific and Technical Information of China (English)
杜彪; 杨可忠; 钟顺时
1995-01-01
The parametric equations and the formulas of unit normal vector and surface element for aparabolic torus reflector antenna are derived and the mechanism of producing multibeam is proposed, Based on physical optics, the radiation pattern formulas for the antenna are given, with which the effects of geometric parameters on the antenna are studied. The good agreement between the calculated patterns and the measured ones shows that the theory is helpful for designing parabolic torus antennas.
A torus patch approximation approach for point projection on surfaces
Liu, Xiao-ming; Yang, Lei; Yong, Jun-Hai; Gu, He-Jin; Sun, Jia-Guang
2009-01-01
International audience; This paper proposes a second order geometric iteration algorithm for point projection and inversion on parametric surfaces. The iteration starts from an initial projection estimation. In each iteration, we construct a second order osculating torus patch to the parametric surface at the previous projection. Then we project the test point onto the torus patch to compute the next projection and its parameter. This iterative process is terminated when the parameter satisfi...
AGN Obscuration from Winds: From Dusty Infrared-Driven to Warm and X-Ray Photoionized
Dorodnitsyn, A.; Kallman, T.
2012-01-01
We present calculations of AGN winds at approximate parsec scales, along with the associated obscuration. We take into account the pressure of infrared radiation on dust grains and the interaction of X-rays from a central black hole with hot and cold plasma. Infrared radiation (IR) is incorporated in radiation-hydrodynamic simulations adopting the flux-limited diffusion approximation. We find that in the range of X-ray luminosities L=0.05 - 0.6L(sub Edd) the Compton-thick part of the flow (aka torus) has an opening angle of approximately 72? -75? regardless of the luminosity. At L 0.1 the outflowing dusty wind provides the obscuration with IR pressure playing a major role. The global flow consists of two phases: the cold flow at inclinations (theta) greater than or approximately 70? and a hot, ionized wind of lower density at lower inclinations. The dynamical pressure of the hot wind is important in shaping the denser IR supported flow. At luminosities less than or equal to 0.1L(sub Edd) episodes of outflow are followed by extended periods when the wind switches to slow accretion.
Development of a repetitive compact torus injector
Onchi, Takumi; McColl, David; Dreval, Mykola; Rohollahi, Akbar; Xiao, Chijin; Hirose, Akira; Zushi, Hideki
2013-10-01
A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. This work has been sponsored by the CRC and NSERC, Canada.
Gauge Theory On The Fuzzy Torus
Bigatti, D
2001-01-01
In this paper a formulation of U(1) gauge theory on a fuzzy torus is discussed. The theory is regulated in both the infrared and ultraviolet. It can be thought of as a non-commutative version of lattice gauge theory on a periodic lattice. The construction of Wilson loops is particularly transparent in this formulation. Following Ishibashi, Iso, Kawai and Kitazawa, we show that certain Fourier modes of open Wilson lines are gauge invariant. We also introduce charged matter fields which can be thought of as fundamentals of the gauge group. These particles behave like charges in a strong magnetic field and are frozen into the lowest Landau levels. The resulting system is a simple matrix quantum mechanics which should reflect much of the physics of charged particles in strong magnetic fields. The present results were first presented as a talk at the Institute for Mathematical Science, Chennai, India; the author wishes to thank Prof. T. R. Govindarajan and the IMS for hospitality and financial support, and the aud...
Statistical Physics Experiments Using Dusty Plasmas
Goree, John
2016-10-01
Compared to other areas of physics research, Statistical Physics is heavily dominated by theory, with comparatively little experiment. One reason for the lack of experiments is the impracticality of tracking of individual atoms and molecules within a substance. Thus, there is a need for a different kind of experimental system, one where individual particles not only move stochastically as they collide with one another, but also are large enough to allow tracking. A dusty plasma can meet this need. A dusty plasma is a partially ionized gas containing small particles of solid matter. These micron-size particles gain thousands of electronic charges by collecting more electrons than ions. Their motions are dominated by Coulomb collisions with neighboring particles. In this so-called strongly coupled plasma, the dust particles self-organize in much the same way as atoms in a liquid or solid. Unlike atoms, however, these particles are large and slow, so that they can be tracked easily by video microscopy. Advantages of dusty plasma for experimental statistical physics research include particle tracking, lack of frictional contact with solid surfaces, and avoidance of overdamped motion. Moreover, the motion of a collection of dust particles can mimic an equilibrium system with a Maxwellian velocity distribution, even though the dust particles themselves are not truly in thermal equilibrium. Nonequilibrium statistical physics can be studied by applying gradients, for example by imposing a shear flow. In this talk I will review some of our recent experiments with shear flow. First, we performed the first experimental test to verify the Fluctuation Theorem for a shear flow, showing that brief violations of the Second Law of Thermodynamics occur with the predicted probabilities, for a small system. Second, we discovered a skewness of a shear-stress distribution in a shear flow. This skewness is a phenomenon that likely has wide applicability in nonequilibrium steady states
Observation of Vortex Patterns in a Magnetized Dusty Plasma System
Institute of Scientific and Technical Information of China (English)
HUANG Feng; YE Maofu; WANG Long; LIU Yanhong
2007-01-01
Vortex patterns of dust particles have been observed in a magnetized dusty plasma system. The formation mechanism of two-dimensional (2D) vortex patterns has been investigated by analysing the forces acting on dust particles and molecular dynamics (MD) simulations in a 2D confined magnetized dusty plasma. It has been found that with a weak confining electric field and a strong magnetic field, the particles' trajectories will form a vortex shape. The simulation results agree with our experimental observations. In our experiments, vortex patterns can be induced via circular rotation of particles by changing the rf (radio-frequency) power in a magnetized dusty plasma.
Application of particle image velocimetry to dusty plasma systems
Williams, Jeremiah D.
2016-06-01
> Particle image velocimetry is a fluid measurement technique that has been used for more than 20 years to characterize the particle transport and thermal state of dusty plasma systems. This manuscript provides an overview of this diagnostic technique, highlighting the strengths and limitations that are associated with its use. Additionally, the variations of this technique that have been applied in the study of dusty plasma systems will be discussed, along with a small selection of measurements that can be made with the technique. Potential future directions for this diagnostic tool within the dusty plasma community will also be discussed.
Gas kinematics in the inner kiloparsec of NGC 1386: a new clue to the torus-galaxy connection?
Lena, D.
2015-09-01
We used the GMOS integral field unit on the Gemini South telescope to investigate the kinematics of the circum-nuclear ionized gas in the Seyfert 2 galaxy NGC 1386. We found that the dominant kinematic components can be explained as a combination of rotation in the large-scale galactic disk and a compact bipolar outflow along the axis of the AGN 'radiation cone'. However, there is also compelling evidence for an additional kinematic component which is consistent with outflow and/or rotation in a plane that is approximately perpendicular to the axis of the AGN radiation cone. We speculate that this is a wind which is both outfowing in the equatorial plane of the torus, and rotating about the axis of the radiation cones. From the emission line surface brightness distribution, we infer the torus inclination and opening angle.
The dusty ballerina skirt of Jupiter
Horanyi, M.; Morfill, G.; Gruen, E.
1993-12-01
We suggest a model to explain the unexpected recurrent dust events that were observed during the Jupiter encounter by the dust detector on board the Ulysses spacecraft. This model is based dust-magnetosphere interactions. Dust particles inside the Jovian magnetosphere collect electrostatic charges and their interaction with the magnetic and electric fields can lead to energization and subsequent ejection. We discuss the dusty regions (ring/halo, `gossamer' ring) and also Io as potential sources for the Ulysses events. This model favors Io as a source. The mass and velocity range of the escaping particles are compatible with the observations, and we also suggest internal periodicities to explain the recurrent nature of the Ulysses dust events.
Dissipative drift instability in dusty plasma
Directory of Open Access Journals (Sweden)
Nilakshi Das
2012-03-01
Full Text Available An investigation has been done on the very low-frequency electrostatic drift waves in a collisional dusty plasma. The dust density gradient is taken perpendicular to the magnetic field B0⃗, which causes the drift wave. In this case, low-frequency drift instabilities can be driven by E1⃗×B0⃗ and diamagnetic drifts, where E1⃗ is the perturbed electric field. Dust charge fluctuation is also taken into consideration for our study. The dust- neutral and ion-neutral collision terms have been included in equations of motion. It is seen that the low-frequency drift instability gets damped in such a system. Both dust charging and collision of plasma particles with the neutrals may be responsible for the damping of the wave. Both analytical and numerical techniques have been used while developing the theory.
Pattern Formation in a Dusty Plasma System
Institute of Scientific and Technical Information of China (English)
黄峰; 叶茂福; 王龙; 江南
2004-01-01
A rich variety of dust patterns have been observed in a capacitively coupled rf discharge dusty plasma system. Dust particles are synthesized through chemical reaction of the filled gas mixture during discharge. Different patterns are formed in different stages of particle growth. In the early stage of particle growth, dust cloud can be formed by a large number of small particles, and its behavior appears to be fluid-like. Such interesting nonlinear phenomena as dust void and complex dust cloud patterns are observed in this stage. As dust particles grow, the particle size and structure can be controlled to follow two different routes. In one of the routes, the particles grow up in a ball-like shape and can be formed into regular lattice and cluster patterns.In the other, the particles grow up in a fractal shape.
Dusty globules in the Crab Nebula
Grenman, T.; Gahm, G. F.; Elfgren, E.
2017-03-01
Context. Dust grains are widespread in the Crab Nebula. A number of small, dusty globules, are visible as dark spots against the background of continuous synchrotron emission in optical images. Aims: Our aim is to catalogue such dusty globules and investigate their properties. Methods: From existing broad-band images obtained with the Hubble Space Telescope, we located 92 globules, for which we derived positions, dimensions, orientations, extinctions, masses, proper motions, and their distributions. Results: The globules have mean radii ranging from 400 to 2000 AU and are not resolved in current infrared images of the nebula. The extinction law for dust grains in these globules matches a normal interstellar extinction law. Derived masses of dust range from 1 to 60 × 10-6M⊙, and the total mass contained in globules constitute a fraction of approximately 2% or less of the total dust content of the nebula. The globules are spread over the outer part of the nebula, and a fraction of them coincide in position with emission filaments, where we find elongated globules that are aligned with these filaments. Only 10% of the globules are coincident in position with the numerous H2-emitting knots found in previous studies. All globules move outwards from the centre with transversal velocities of 60 to 1600 km s-1, along with the general expansion of the remnant. We discuss various hypotheses for the formation of globules in the Crab Nebula. Based on observations collected with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute.
Molecular dynamics simulations of magnetized dusty plasmas
Piel, Alexander; Reichstein, Torben; Wilms, Jochen
2012-10-01
The combination of the electric field that confines a dust cloud with a static magnetic field generally leads to a rotation of the dust cloud. In weak magnetic fields, the Hall component of the ion flow exerts a drag force that sets the dust in rotation. We have performed detailed molecular-dynamics simulations of the dynamics of torus-shaped dust clouds in anodic plasmas. The stationary flow [1] is characterized by a shell structure in the laminar dust flow and by the spontaneous formation of a shear-flow around a stationary vortex. Here we present new results on dynamic phenomena, among them fluctuations due to a Kelvin-Helmholtz instability in the shear-flow. The simulations are compared with experimental results. [4pt] [1] T. Reichstein, A. Piel, Phys. Plasmas 18, 083705 (2011)
Research Into a Neon Spectral Line Profile of Dusty Plasma
Pikalev, Aleksandr
2014-01-01
Ordered dusty structures influence plasma conditions. This influence can be revealed, when plasma spectral characteristics change, as dusty particles are injected. For example, a variation in the atomic temperature leads to a variation in the profiles of spectral lines. We studied the profile of a 585 nm neon spectral line in the dusty structures. The structures levitated in a positive column of a glow discharge at a pressure of 50-150 Pa and with a current of 1-9 mA. We scanned the profile with the use of a Fabry-Perot interferometer, by changing the air pressure between the interferometer mirrors. To process the data, a special algorithm was developed. The algorithm is resistant to a noise and a scanning speed instability. We have found an upper bound of the impact of dusty structures on the profile width. The appearance of macroparticles changes the atomic plasma temperature less than by 10 K.
Three Millennia of Southwestern North American Dustiness and Future Implications.
Routson, Cody C; Overpeck, Jonathan T; Woodhouse, Connie A; Kenney, William F
2016-01-01
Two sediment records of dust deposition from Fish Lake, in southern Colorado, offer a new perspective on southwest United States (Southwest) aridity and dustiness over the last ~3000 years. Micro scanning X-ray fluorescence and grain size analysis provide separate measures of wind-deposited dust in the lake sediment. Together these new records confirm anomalous dustiness in the 19th and 20th centuries, associated with recent land disturbance, drought, and livestock grazing. Before significant anthropogenic influences, changes in drought frequency and aridity also generated atmospheric dust loading. Medieval times were associated with high levels of dustiness, coincident with widespread aridity. These records indicate the Southwest is naturally prone to dustiness. As global and regional temperatures rise and the Southwest shifts toward a more arid landscape, the Southwest will likely become dustier, driving negative impacts on snowpack and water availability, as well as human health.
Modelling of dusty plasma properties by computer simulation methods
Energy Technology Data Exchange (ETDEWEB)
Baimbetov, F B [IETP, Al Farabi Kazakh National University, 96a, Tole bi St, Almaty 050012 (Kazakhstan); Ramazanov, T S [IETP, Al Farabi Kazakh National University, 96a, Tole bi St, Almaty 050012 (Kazakhstan); Dzhumagulova, K N [IETP, Al Farabi Kazakh National University, 96a, Tole bi St, Almaty 050012 (Kazakhstan); Kadyrsizov, E R [Institute for High Energy Densities of RAS, Izhorskaya 13/19, Moscow 125412 (Russian Federation); Petrov, O F [IETP, Al Farabi Kazakh National University, 96a, Tole bi St, Almaty 050012 (Kazakhstan); Gavrikov, A V [IETP, Al Farabi Kazakh National University, 96a, Tole bi St, Almaty 050012 (Kazakhstan)
2006-04-28
Computer simulation of dusty plasma properties is performed. The radial distribution functions, the diffusion coefficient are calculated on the basis of the Langevin dynamics. A comparison with the experimental data is made.
Ideal gas behavior of a strongly coupled complex (dusty) plasma.
Oxtoby, Neil P; Griffith, Elias J; Durniak, Céline; Ralph, Jason F; Samsonov, Dmitry
2013-07-05
In a laboratory, a two-dimensional complex (dusty) plasma consists of a low-density ionized gas containing a confined suspension of Yukawa-coupled plastic microspheres. For an initial crystal-like form, we report ideal gas behavior in this strongly coupled system during shock-wave experiments. This evidence supports the use of the ideal gas law as the equation of state for soft crystals such as those formed by dusty plasmas.
Steady-State Plasmas in KT5D Magnetized Torus
Institute of Scientific and Technical Information of China (English)
ZHU Zhenhua; LIU Wandong; WAN Baonian; ZHAO Yanping; LI Jiangang; YAN Longwen; YANG Qingwei; DING Xuantong; XU Min; YU Yi; WANG Zhijiang; LU Ronghua; WEN Yizhi; YU Changxuan; MA Jinxiu; WAN Shude
2007-01-01
Steady-state plasma generated by electron cyclotron resonance (ECR) wave in the KT5D magnetized torus was studied using a fast high-resolution camera and Langmuir probes. It was found that both the discharge patterns taken by the camera and the plasma parameters measured by the probes were very sensitive to the working gas pressure and the magnetic configuration of the torus both without and with vertical fields. There existed fast vertical motion of the plasma. Tentative discussion is presented about the observed phenomena such as the bright resonance layer at a high gas pressure and the wave absorption mechanism at a low pressure. Further explanations should be found.
An approach to renormalization on the n-torus.
Rockmore, Daniel; Siegel, Ralph; Tongring, Nils; Tresser, Charles
1991-07-01
The coding theory of rotations (by inspecting closely their relation to flows) and the continued fractions algorithm (by considering even two-coloring of the integers with a given proportion of, say, blue and red) are revisited. Then, even n-coloring of the integers is defined. This allows one to code rotations on the (n-1)-torus by considering linear flows on the n-torus and yields a simple geometric approach to renormalization on tori by first return maps on the coding regions.
The CLAS12 Torus Detector Magnet at Jefferson Laboratory
Energy Technology Data Exchange (ETDEWEB)
Luongo, Cesar [Jefferson Lab; Ballard, Joshua [Jefferson Lab; Biallas, George [Jefferson Lab; Elouadrhiri, Latifa [Jefferson Lab; Fair, Ruben [Jefferson Lab; Ghoshal, Probir [Jefferson Lab; Kashy, Dave [Jefferson Lab; Legg, Robert [Jefferson Lab; Pastor, Orlando [Jefferson Lab; Rajput-Ghoshal, Renuka [Jefferson Lab; Rode, Claus [Jefferson Lab; Wiseman, Mark [Jefferson Lab; Young, Glenn [Jefferson Lab; Elementi, Luciano [Fermilab; Krave, Steven [Fermilab; Makarov, Alexander [Fermilab; Nobrega, Fred [Fermilab; Velev, George [Fermilab
2015-12-17
The CLAS12 Torus is a toroidal superconducting magnet, which is part of the detector for the 12-GeV accelerator upgrade at Jefferson Laboratory (JLab). The coils were wound/fabricated by Fermilab, with JLab responsible for all other parts of the project scope, including design, integration, cryostating the individual coils, installation, cryogenics, I&C, etc. This paper provides an overview of the CLAS12 Torus magnet features and serves as a status report of its installation in the experimental hall. Completion and commissioning of the magnet is expected in 2016.
Comments on a full quantization of the torus
Velhinho, J M
1998-01-01
Gotay showed that a representation of the whole Poisson algebra of the torus given by geometric quantization is irreducible with respect to the most natural overcomplete set of observables. We study this representation and argue that it cannot be considered as physically acceptable, since classically bounded observables are quantized by operators with unbounded spectrum. This in turn can be traced back to the non implementation of functional relations among observables. Effectively, the latter amounts to lifting the constraints that compactify both directions in the torus.
Direct torus venting analysis for Chinshan BWR-4 plant with MARK-I containment
Energy Technology Data Exchange (ETDEWEB)
Yuann, Yng-Ruey, E-mail: ryyuann@iner.gov.tw
2017-03-15
Highlights: • Study the effectiveness of Direct Torus Venting System (DTVS) during extended SBO of 24 h for Chinshan MARK-I plant. • Containment response is analyzed by GOTHIC based on boundary conditions from RETRAN calculation. • Analyses are performed with and without DTVS, respectively. • Suppression pool is sub-divided and thermal stratification is observed. - Abstract: The Chinshan plant, owned by Taiwan Power Company, has twin units of BWR-4 reactor and MARK-I containment. Both units have been operating at rated core thermal power of 1840 MWt. The existing Direct Torus Venting System (DTVS) is the main system used for venting the containment during the extended station blackout event. The purpose of this paper is to study the effects of the DTVS venting on the response of the containment pressure and temperature. The reactor is depressurized by manually opening the safety relief valves (SRVs) during the SBO, which causes the mass and energy to be discharged into and heat up the suppression pool. The RETRAN model is used to calculate the Nuclear Steam Supply System (NSSS) response and generate the SRV blowdown conditions, including SRV pressure, enthalpy, and mass flow rate. These conditions are then used as the time-dependent boundary conditions for the GOTHIC code to calculate the containment pressure and temperature response. The DTVS model is established in the GOTHIC model based on the venting size, venting piping loss, venting initiation time, and venting source. The lumped volume model, 1-D coarse-mesh model, and 3-D coarse-mesh model are considered in the torus volume. The calculation is first done without DTVS venting to establish a reference basis. Then a case with DTVS available is performed. Comparison of the two cases shows that the existing DTVS design is effective in mitigating the severity of the containment pressure and temperature transients. The results also show that the 1-D coarse-mesh model may not be appropriate since a
Quasiperiodicity and Torus Breakdown in a Power Electronic DC/DC Converter
DEFF Research Database (Denmark)
Zhusubaliyev, Zhanybai; Soukhoterin, Evgeniy; Mosekilde, Erik
2007-01-01
This paper discusses the mechanisms of torus formation and torus destruction in a dc/dc converter with relay control and hysteresis. We establish a chart of the dynamical modes in the input voltage versus load resistance parameter plane. This chart displays several different torus bifurcations...
Frantic activity revealed in dusty stellar factories
2009-01-01
Thanks to the Very Large Telescope's acute and powerful near-infrared eye, astronomers have uncovered a host of new young, massive and dusty stellar nurseries in nearby galaxy NGC 253. The centre of this galaxy appears to harbour a twin of our own Milky Way's supermassive black hole. ESO PR Photo 02a/09 The Spiral Galaxy NGC 253 Astronomers from the Instituto de Astrofísica de Canarias (Spain) used NACO, a sharp-eyed adaptive optics instrument on ESO's Very Large Telescope (VLT), to study the fine detail in NGC 253, one of the brightest and dustiest spiral galaxies in the sky. Adaptive Optics (AO) corrects for the blurring effect introduced by the Earth's atmosphere. This turbulence causes the stars to twinkle in a way that delights poets, but frustrates astronomers, since it smears out the images. With AO in action the telescope can produce images that are as sharp as is theoretically possible, as if the telescope were in space. NACO revealed features in the galaxy that were only 11 light-years across. "Our observations provide us with so much spatially resolved detail that we can, for the first time, compare them with the finest radio maps for this galaxy -- maps that have existed for more than a decade," says Juan Antonio Fernández-Ontiveros, the lead author of the paper reporting the results [1]. Astronomers identified 37 distinct bright regions, a threefold increase on previous results, packed into a tiny region at the core of the galaxy, comprising just one percent of the galaxy's total size. The astronomers combined their NACO images with data from another VLT instrument, VISIR, as well as with images from the NASA/ESA Hubble Space Telescope and radio observations made by the Very Large Array and the Very Large Baseline Interferometer. Combining these observations, taken in different wavelength regimes, provided a clue to the nature of these regions. "We now think that these are probably very active nurseries that contain many stars bursting from their
Sarty, Gordon E.; Atkins, M. Stella; Olatunbosun, Femi; Chizen, Donna; Loewy, John; Kendall, Edward J.; Pierson, Roger A.
1999-10-01
A new numerical wavelet transform, the discrete torus wavelet transform, is described and an application is given to the denoising of abdominal magnetic resonance imaging (MRI) data. The discrete tori wavelet transform is an undecimated wavelet transform which is computed using a discrete Fourier transform and multiplication instead of by direct convolution in the image domain. This approach leads to a decomposition of the image onto frames in the space of square summable functions on the discrete torus, l2(T2). The new transform was compared to the traditional decimated wavelet transform in its ability to denoise MRI data. By using denoised images as the basis for the computation of a nuclear magnetic resonance spin-spin relaxation-time map through least squares curve fitting, an error map was generated that was used to assess the performance of the denoising algorithms. The discrete torus wavelet transform outperformed the traditional wavelet transform in 88% of the T2 error map denoising tests with phantoms and gynecologic MRI images.
Computational Fluid Dynamics Analysis of the Venturi Dustiness Tester.
Dubey, Prahit; Ghia, Urmila; Turkevich, Leonid A
2017-05-01
Dustiness quantifies the propensity of a finely divided solid to be aerosolized by a prescribed mechanical stimulus. Dustiness is relevant wherever powders are mixed, transferred or handled, and is important in the control of hazardous exposures and the prevention of dust explosions and product loss. Limited quantities of active pharmaceutical powders available for testing led to the development (at University of North Carolina) of a Venturi-driven dustiness tester. The powder is turbulently injected at high speed (Re ~ 2 × 10(4)) into a glass chamber; the aerosol is then gently sampled (Re ~ 2 × 10(3)) through two filters located at the top of the chamber; the dustiness index is the ratio of sampled to injected mass of powder. Injection is activated by suction at an Extraction Port at the top of the chamber; loss of powder during injection compromises the sampled dustiness. The present work analyzes the flow inside the Venturi Dustiness Tester, using an Unsteady Reynolds-Averaged Navier-Stokes formulation with the k-ω Shear Stress Transport turbulence model. The simulation considers single-phase flow, valid for small particles (Stokes number Stk <1). Results show that ~ 24% of fluid-tracers escape the tester before the Sampling Phase begins. Dispersion of the powder during the Injection Phase results in a uniform aerosol inside the tester, even for inhomogeneous injections, satisfying a necessary condition for the accurate evaluation of dustiness. Simulations are also performed under the conditions of reduced Extraction-Port flow; results confirm the importance of high Extraction-Port flow rate (standard operation) for uniform distribution of fluid tracers. Simulations are also performed under the conditions of delayed powder injection; results show that a uniform aerosol is still achieved provided 0.5 s elapses between powder injection and sampling.
The Quest for Dusty Primeval Galaxies
Mancuso, C.; Lapi, A.; Danese, L.
2016-06-01
We exploit the continuity equation approach and the 'main sequence' star-formation timescales to show that the observed high abundance of galaxies with stellar masses ? a few >10^10 M_⊙ at redshift z >? 4 implies the existence of a galaxy population featuring large star formation rates (SFRs) ψ >? 10^2 M_⊙ yr^-1 in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for zdensity at z 30 M_⊙ yr^-1 cannot be estimated relying on the UV luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from AzTEC-LABOCA, SCUBA-2 and ALMA-SPT surveys are already digging into it. We substantiate how an observational strategy based on a color preselection in the far-IR or (sub-)mm band with Herschel and SCUBA-2, supplemented by photometric data via on-source observations with ALMA, can allow to reconstruct the bright end of the SFR functions out to z ? 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)mm observations by ALMA and NIKA2 and/or radio observations by SKA and its precursors.
Pro-Torus Actions on Poincaré Duality Spaces
Indian Academy of Sciences (India)
Ali Özkurt; Doğan Dönmez
2006-08-01
In this paper, it is shown that some of the results of torus actions on Poincaré duality spaces, Borel’s dimension formula and topological splitting principle to local weights, hold if `torus’ is replaced by `pro-torus’.
Recursive representation of the torus 1-point conformal block
Hadasz, Leszek; Suchanek, Paulina
2009-01-01
The recursive relation for the 1-point conformal block on a torus is derived and used to prove the identities between conformal blocks recently conjectured by R. Poghossian. As an illustration of the efficiency of the recurrence method the modular invariance of the 1-point Liouville correlation function is numerically analyzed.
Photodisintegration of a Bound State on the Torus
Meyer, Harvey B
2012-01-01
In this article the cross-section for the photodisintegration of a bound state is expressed, order by order in the multipole expansion, in terms of matrix elements between states living on the three-dimensional torus. The motivation is to make the process amenable to Monte-Carlo simulations. The case of the deuteron is discussed.
On projections in the noncommutative 2-torus algebra
Eckstein, Michał
2011-01-01
We investigate a set of functional equations defining an arbitrary projection in the noncommutative 2-torus algebra A_{\\theta}. The exact solutions of those provide various generalisations of the Power-Rieffel projection. By identifying the corresponding K_0 classes we get an insight into the general structure of projections in A_{\\theta}.
On Projections in the Noncommutative 2-Torus Algebra
Eckstein, Michał
2014-03-01
We investigate a set of functional equations defining a projection in the noncommutative 2-torus algebra A_{θ}. The exact solutions of these provide various generalisations of the Powers-Rieffel projection. By identifying the corresponding K_0(A_{θ}) classes we get an insight into the structure of projections in A_{θ}.
Complete spectral data for analytic Anosov maps of the torus
Slipantschuk, J.; Bandtlow, O. F.; Just, W.
2017-07-01
Using analytic properties of Blaschke factors we construct a family of analytic hyperbolic diffeomorphisms of the torus for which the spectra of the associated transfer operator acting on a suitable Hilbert space can be computed explicitly. As a result, we obtain expressions for the decay of correlations of analytic observables without resorting to any kind of perturbation argument.
Atomic force microscopy of torus-bearing pit membranes
Roland R. Dute; Thomas Elder
2011-01-01
Atomic force microscopy was used to compare the structures of dried, torus-bearing pit membranes from four woody species, three angiosperms and one gymnosperm. Tori of Osmanthus armatus are bipartite consisting of a pustular zone overlying parallel sets of microfibrils that form a peripheral corona. Microfibrils of the corona form radial spokes as they traverse the...
Io Plasma Torus Ion Composition: Voyager, Galileo, Cassini
Bagenal, Fran; Nerney, Edward; Steffl, Andrew Joseph
2016-10-01
With JAXA's Hisaki spacecraft in orbit around Earth gathering information on the Io plasma torus and NASA's Juno mission measuring plasma conditions in the jovian magnetosphere, the time is ripe for a re-evaluation of earlier observations of the plasma torus to assess evidence for temporal variations. In particular, we are interested in exploring the ion composition of the torus and whether there is evidence of the ultimate source – the volcanic gases from Io – have deviated from SO2. We use the latest CHIANTI 8.0 atomic database to analyze UV spectra of the torus from Voyager, Galileo and Cassini as well as with the physical chemistry model of Delamere, Steffl and Bagenal (2005). We find that contrary to earlier analyses of Voyager data (e.g. Shemansky 1987; 1988) that produced a composition requiring a neutral source of O/S~4, we find an ion composition that is consistent with the Cassini UVIS data (Steffl et al. 2004) and a neutral O/S~2, consistent with SO2.
Evaluation of the Dustiness of Different Kaolin Samples.
López-Lilao, Ana; Bruzi, Marine; Sanfélix, Vicenta; Gozalbo, Ana; Mallol, Gustavo; Monfort, Eliseo
2015-01-01
Several samples of kaolin with different mean particle size were prepared and tested using the continuous drop method, one of the reference test methods according to standard EN 15051:2006 "Workplace atmospheres - Measurement of the dustiness of bulk materials - Requirements and reference test methods." On the other hand, with a view to relating the dustiness of the materials to their properties, particle size distribution, specific surface area, and Hausner ratio of these samples were determined. This article presents a characterization of these samples and an assessment of the influence of some material parameters on dustiness. The results show that dustiness may significantly be affected by mean particle size, specific surface area, and Hausner ratio. Moreover, it is highlighted that a detailed study of the influence of fine particles content on the dustiness was carried out. This information is deemed essential for establishing the most efficient preventive and/or corrective measures to reduce the generation of fugitive emissions of particulate matter during kaolin processing, both into the outside atmosphere (air pollution) and inside the facilities (occupational health).
Space dusty plasmas: recent developments, advances, and unsolved problems
Popel, Sergey; Zelenyi, Lev
2016-07-01
The area of space dusty plasma research is a vibrant subfield of plasma physics that belongs to frontier research in physical sciences. This area is intrinsically interdisciplinary and encompasses astrophysics, planetary science, and atmospheric science. Dusty plasmas are ubiquitous in the universe; examples are proto-planetary and solar nebulae, molecular clouds, supernovae explosions, interplanetary medium, circumsolar rings, and asteroids. Within the solar system, we have planetary rings (e.g., Saturn and Jupiter), Martian atmosphere, cometary tails and comae, dust at the Moon, etc. Dust and dusty plasmas are also found in the vicinity of artificial satellites and space stations. The present review covers the main aspects of the area of space dusty plasma research. Emphasis is given to the description of dusty plasmas at the Moon which is important from the viewpoint of the future lunar missions and lunar observatory. This work was supported in part by the Presidium of the Russian Academy of Sciences (under Fundamental Research Program No. 7, "Experimental and Theoretical Study of the Solar System Objects and Stellar Planet Systems. Transient Explosion Processes in Astrophysics" and the Russian Foundation for Basic Research (Project No. 15-02-05627-a).
Charge density fluctuation of low frequency in a dusty plasma
Institute of Scientific and Technical Information of China (English)
李芳; 吕保维; O.Havnes
1997-01-01
The charge density fluctuation of low frequency in a dusty plasma, which is derived from the longitudinal dielectric permittivity of the dusty plasma, has been studied by kinetic theory. The results show that the P value, which describes the relative charge density on the dust in the plasma, and the charging frequency of a dust particle Ωc, which describes the ratio of charge changing of the dust particles, determine the character of the charge density fluctuation of low frequency. For a dusty plasma of P<<1, when the charging frequency Ωc is much smaller than the dusty plasma frequency wd, there is a strong charge density fluctuation which is of character of dust acoustic eigen wave. For a dusty plasma of P>>1, when the frequency Ωc, is much larger than wd there are weaker fluctuations with a wide spectrum. The results have been applied to the ionosphere and the range of radius and density of dust particles is found, where a strong charge density fluctuation of low frequency should exist.
The physics and chemistry of dusty plasmas: A laboratory and theoretical investigation
Whipple, E. C.
1986-01-01
Theoretical work on dusty plasmas was conducted in three areas: collective effects in a dusty plasma, the role of dusty plasmas in cometary atmospheres, and the role of dusty plasmas in planetary atmospheres (particularly in the ring systems of the giant planets). Laboratory investigations consisted of studies of dust/plasma interactions and stimulated molecular excitation and infrared emission by charged dust grains. Also included is a list of current publications.
A brief review of dusty plasma effects in the solar system
Energy Technology Data Exchange (ETDEWEB)
Winske, D.
1997-08-01
Dusty plasmas are commonly found in the solar system and in the rest of space. In this paper we briefly describe some of the more common dusty plasmas: the rings of Saturn, dust tails of comets, dust streams from Jupiter, and noctilucent clouds in the upper atmosphere. We also discuss some of the theoretical issues related to grain charging, dust particle dynamics, waves in dusty plasmas, and dusty plasma crystals.
Analysis on the Formation Reason of a Dusty Weather in the Midwest of Hulun Buir City
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
[Objective] The research aimed to analyze the formation reason of a dusty weather in the midwest of Hulun Buir City. [Method] By combining the synoptic method with the ecological environment variation, the occurrence and influence of a typical dusty weather which happened in the midwest of Hulun Buir City on May 30, 2006 were analyzed. The occurrence mechanism of dusty weather in the city was elaborated deeply, and the source of dusty weather was put forward from the ecological environment variation angle. ...
Dark solitons in a complex (dusty) plasma
Zhdanov, Sergey; Heidemann, Ralf; Thoma, Markus; Suetterlin, Robert; Thomas, Hubertus; Morfill, Gregor
We address the dynamics of nonlinear solitary waves which are impact-excited in a dense complex (dusty) plasma using neon rf and dc gas discharges at pressures 18-35 Pa. Complex plasmas are low-pressure, low-temperature plasmas containing microparticles. Due to their special properties, complex plasmas provide an excellent system to study fluid flow dynamics including solitons. The microparticles are highly charged up by collecting plasma ions and electrons. They can be visualized individually with scattered light from a laser beam, which is recorded with a CCD camera. The solitary wave structures we observe propagating in the complex plasma cloud are domi-nantly of a rarefactive type, hence resemble so called dissipative dark solitons (DDS) important in a number of astrophysical applications. These waves are interesting as an indicator of the peculiar properties of dispersion and nonlinearity of the medium in which they propagate. Under our experimental conditions DDS travelled at a speed of about 15-20 mm/s. Although the complex plasma used in these experiments was shown to be highly dissipative, the nonlinear wave patterns were not overdamped and clearly detectable. We observed that DDS could self-support its propagation for much longer times than dissipation would imply. The physical mechanism, determining the behaviour of dissipative rarefactive solitary waves is still under debate. Therefore, the search for physically realistic systems that can support stable solitary waves is of considerable interest. The message we want to communicate in the report is rather simple: A strongly coupled complex plasma provides a promising tool to study dissipative nonlinear structures —in particular the dissipative dark solitons— at the kinetic level. For the first time we have observed recognizable DDS in a complex plasma cloud and characterized them. Further experiments also under microgravity conditions onboard the ISS are planned within the project PK-4.
Dusty Plasma Effects in the Interplanetary Medium?
Mann, Ingrid; Issautier, Karine; Meyer-Vernet, Nicole; Le Chat, Gaétan; Czechowski, Andrzej; Zaslavsky, Arnaud; Zouganelis, Yannis; Belheouane, Soraya
Cosmic dust particles exist in a variety of compositions and sizes in the interplanetary medium. There is little direct information on the composition, but those interplanetary dust particles that are collected in the upper Earth’s atmosphere and can be studied in the laboratory typically have an irregular, sometimes porous structure on scales carbide, iron-nickel and iron-sulfur compounds, calcium- and aluminum oxides, and chemical compounds that contain a large mass fraction of carbon (e.g. carbonaceous species). A fraction of the dust originates from comets, but because of their bulk material temperature of about 280 K near 1 AU, most icy compounds have disappeared. The dust particles are embedded in the solar wind, a hot plasma with at 1 AU kinetic temperatures around 100 000 K and flow direction nearly radial outward from the Sun at supersonic bulk velocities around 400 km/s. Since the dust particles carry an electric surface charge they are subject to electromagnetic forces and the nanodust particles are efficiently accelerated to velocities of order of solar wind speed. The acceleration of the nanodust is similar, but not identical to the formation of pick-up ions. The S/WAVES radio wave instrument on STEREO measured a flux of nanodust at 1 AU [1]. The nanodust probably forms in the region inward of 1 AU and is accelerated by the solar wind as discussed. We also discuss the different paths of dust - plasma interactions in the interplanetary medium and their observations with space experiments. Comparing these interactions we show that the interplanetary medium near 1 AU can in many cases be described as “dust in plasma" rather than "dusty plasma”. [1] S. Belheouane, N. Meyer-Vernet, K. Issautier, G. Le Chat, A. Zaslavsky, Y. Zouganelis, I. Mann, A. Czechowski: Dynamics of nanoparticles detected at 1 AU by S/WAVES onboard STEREO spacecraft, in this session.
Jeans instability of a dusty plasma with dust charge variations
Energy Technology Data Exchange (ETDEWEB)
Hakimi Pajouh, H., E-mail: hakimi@alzahra.ac.ir; Afshari, N. [Faculty of Physics, Alzahra University, P. O. Box 19938-93973, Tehran (Iran, Islamic Republic of)
2015-09-15
The effect of the dust charge variations on the stability of a self-gravitating dusty plasma has been theoretically investigated. The dispersion relation for the dust-acoustic waves in a self-gravitating dusty plasma is obtained. It is shown that the dust charge variations have significant effects. It increases the growth rate of instability and the instability cutoff wavenumbers. It is found that by increasing the value of the ions temperature and the absolute value of the equilibrium dust charge, the cutoff wavenumber decreases and the stability region is extended.
Jeans instability with exchange effects in quantum dusty magnetoplasmas
Energy Technology Data Exchange (ETDEWEB)
Jamil, M., E-mail: jamil.gcu@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rasheed, A. [Department of Physics, Government College University, Faisalabad 38000 (Pakistan); Rozina, Ch. [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Jung, Y.-D. [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of); Salimullah, M. [Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh)
2015-08-15
Jeans instability is examined in magnetized quantum dusty plasmas using the quantum hydrodynamic model. The quantum effects are considered via exchange-correlation potential, recoil effect, and Fermi degenerate pressure, in addition to thermal effects of plasma species. It is found that the electron exchange and correlation potential have significant effects over the threshold value of wave vector and Jeans instability. The presence of electron exchange and correlation effect shortens the time of dust sound that comparatively stabilizes the self gravitational collapse. The results at quantum scale are helpful in understanding the collapse of the self-gravitating dusty plasma systems.
Energy Technology Data Exchange (ETDEWEB)
Arbanas, G; Elster, C; Escher, J; Mukhamedzanov, A; Nunes, F; Thompson, I J
2012-02-24
The TORUS collaboration derives its name from the research it focuses on, namely the Theory of Reactions for Unstable iSotopes. It is a Topical Collaboration in Nuclear Theory, and funded by the Nuclear Theory Division of the Office of Nuclear Physics in the Office of Science of the Department of Energy. The funding supports one postdoctoral researcher for the years 1 through 3. The collaboration brings together as Principal Investigators a large fraction of the nuclear reaction theorists currently active within the USA. The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. This multi-institution collaborative effort is directly relevant to three areas of interest: the properties of nuclei far from stability; microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory.
Particle Distribution Of A Moon-Fed Dust Torus
Jamrath, E.; Makuch, M.; Spahn, F.
2008-09-01
Enceladus' south-polar gey- sers support a huge gas-dust plume towering the south pole of the moon. It is considered to be the main source Saturns E-ring, the largest dust complex of the solar system. Contrary to the spherically sym- metric impactor ejecta dust cre- ation, the dust plume provides a directed particle outflow from the moon. Using a simple probabilistic model, we study the effects of this asymmetric dust ejection on Enceladus' dust torus. Dust con- figurations are described by par- ticle distribution functions and the dynamical properties of the system are adressed through a set of transformations. The re- sulting distribution function of orbital elements describes the unperturbed dust torus. We showcase the differences in the resulting particle distributions between impactor ejecta pro- cesses and dust production by Enceladus plume, modeled by a directed point-sized source. The obtained orbital element distri- bution is compared to the results of numerical simulations of the problem.
The Gauss-Bonnet Theorem for the noncommutative two torus
Connes, Alain
2009-01-01
In this paper we show that the value at zero of the zeta function of the Laplacian on the non-commutative two torus, endowed with its canonical conformal structure, is independent of the choice of the volume element (Weyl factor) given by a (non-unimodular) state. We had obtained, in the late eighties, in an unpublished computation, a general formula for this value at zero involving modified logarithms of the modular operator of the state. We give here the detailed computation and prove that the result is independent of the Weyl factor as in the classical case, thus proving the analogue of the Gauss-Bonnet theorem for the noncommutative two torus.
Fukaya categories of the torus and Dehn surgery.
Lekili, Yanki; Perutz, Timothy
2011-05-17
This paper is a companion to the authors' forthcoming work extending Heegaard Floer theory from closed 3-manifolds to compact 3-manifolds with two boundary components via quilted Floer cohomology. We describe the first interesting case of this theory: the invariants of 3-manifolds bounding S(2) [symbol: see text] T(2), regarded as modules over the Fukaya category of the punctured 2-torus. We extract a short proof of exactness of the Dehn surgery triangle in Heegaard Floer homology. We show that A(∞)-structures on the graded algebra A formed by the cohomology of two basic objects in the Fukaya category of the punctured 2-torus are governed by just two parameters (m(6), m(8)), extracted from the Hochschild cohomology of A. For the Fukaya category itself, m(6) ≠ 0.
Initial Diagnostics for the National Spherical Torus Experiment
Energy Technology Data Exchange (ETDEWEB)
A.L. Roquemore; B. McCormack; D. Johnson; H. Kugel; R. Kaita; and the NSTX Team
1999-06-01
The spherical torus (ST) approach to magnetic confinement has many attractive features as both a fusion reactor concept and a volume neutron source. The National Spherical Torus Experiment (NSTX) is under construction at the Princeton Plasma Physics Laboratory (PPPL), and it is designed to achieve plasma parameters needed for a proof-of-principle test of the ST concept. Discharges with magnetic fields of 2.3 kG on axis and plasma currents of 1 MA will be heated with 6 MW of radio frequency (RF) power and 5 MW of neutral beams, and pulse lengths up to 5 seconds are planned. Central electron temperatures of about 4 keV are expected with RF heating, and theoretical studies show that high values of b and b{sub n} can be achieved.
Combinatorial realizations of crystals via torus actions on quiver varieties
Sam, Steven V
2012-01-01
Consider Kashiwara's crystal associated to a highest weight representation of a symmetric Kac--Moody algebra. There is a geometric realization of this object using Nakajima's quiver varieties. In many particular cases it can also be realized by elementary combinatorial methods. Here we propose a framework for extracting combinatorial realizations from the geometric picture: we construct certain torus actions on the quiver varieties and use Morse theory to index the irreducible components by connected components of the subvariety of torus fixed points. We then discuss the case of affine sl(n). There the fixed point components are just points, and are naturally indexed by multi-partitions. There is some choice in our construction, leading to a family of combinatorial realizations for each highest weight crystal. In the case of the crystal of the fundamental representation we recover a family of realizations which was recently constructed by Fayers. This gives a more conceptual proof of Fayers' result as well as...
Short interval expansion of R\\'enyi entropy on torus
Chen, Bin; Zhang, Jia-ju
2016-01-01
We investigate the short interval expansion of the R\\'enyi entropy for two-dimensional conformal field theory (CFT) on a torus. We require the length of the interval $\\ell$ to be small with respect to the spatial and temporal sizes of the torus. The operator product expansion of the twist operators allows us to compute the short interval expansion of the R\\'enyi entropy at any temperature. In particular, we pay special attention to the large $c$ CFTs dual to the AdS$_3$ gravity and its cousins. At both low and high temperature limits, we read the R\\'enyi entropies to order $\\ell^6$, and find good agreements with holographic results. Moreover, the expansion allows us to read $1/c$ contribution, which is hard to get by expanding the thermal density matrix. We generalize the study to the case with the chemical potential as well.
A Riemann-Roch theorem for the noncommutative two torus
Khalkhali, Masoud; Moatadelro, Ali
2014-12-01
We prove the analogue of the Riemann-Roch formula for the noncommutative two torus Aθ = C(Tθ2)equipped with an arbitrary translation invariant complex structure and a Weyl factor represented by a positive element k ∈C∞(Tθ2). We consider a topologically trivial line bundle equipped with a general holomorphic structure and the corresponding twisted Dolbeault Laplacians. We define a spectral triple (Aθ , H , D) that encodes the twisted Dolbeault complex of Aθ and whose index gives the left hand side of the Riemann-Roch formula. Using Connes' pseudodifferential calculus and heat equation techniques, we explicitly compute the b2 terms of the asymptotic expansion of Tr(e-tD2) . We find that the curvature term on the right hand side of the Riemann-Roch formula coincides with the scalar curvature of the noncommutative torus recently defined and computed in Connes and Moscovici (2014) and independently computed in Fathizadeh and Khalkhali (2014).
Fuzzy Torus and q-Deformed Lie Algebra
Nakayama, R
2006-01-01
It will be shown that the defining relations for fuzzy torus and deformed (squashed) sphere proposed by J. Arnlind, et al (hep-th/0602290) can be rewriten as a new algebra which contains q-deformed commutators. The quantum parameter q (|q|=1) is a function of \\hbar. It is shown that the q --> 1 limit of the algebra with the parameter \\mu <0 describes fuzzy S^2 and that the squashed S^2 with q \
Exact solution of an su(n) spin torus
Hao, Kun; Li, Guang-Liang; Yang, Wen-Li; Shi, Kangjie; Wang, Yupeng
2016-01-01
The trigonometric su(n) spin chain with anti-periodic boundary condition (su(n) spin torus) is demonstrated to be Yang-Baxter integrable. Based on some intrinsic properties of the R-matrix, certain operator product identities of the transfer matrix are derived. These identities and the asymptotic behavior of the transfer matrix together allow us to obtain the exact eigenvalues in terms of an inhomogeneous T-Q relation via the off-diagonal Bethe Ansatz.
Exact solution of an su(n) spin torus
Hao, Kun; Cao, Junpeng; Li, Guang-Liang; Yang, Wen-Li; Shi, Kangjie; Wang, Yupeng
2016-07-01
The trigonometric su(n) spin chain with anti-periodic boundary condition (su(n) spin torus) is demonstrated to be Yang-Baxter integrable. Based on some intrinsic properties of the R-matrix, certain operator product identities of the transfer matrix are derived. These identities and the asymptotic behavior of the transfer matrix together allow us to obtain the exact eigenvalues in terms of an inhomogeneous T - Q relation via the off-diagonal Bethe Ansatz.
Gastric pseudo-ulcers: membrana angularis and pyloric torus defects.
Peavy, P W; Clements, J L; Weens, H S
1975-03-01
The membrana angularis and pyloric torus defects are two physiologic bulges which can simulate ulcerations along the lesser curvature of the stomach. The muscular anatomy of the stomach and the mechanism which produces these pseudo-ulcers are discussed. Both pseudoniches can be seen transiently in normal individuals but occasionally are such prominence as to become diagnostic pitfalls. The features and significance of each pseudo-ulcer are reviewed in an attempt to facilitate recognition on the upper gastrointestinal barium examination.
Gauge Fields on Torus and Partition Function of Strings
Nakamula, Atsushi
2014-01-01
In this paper we consider the interrelation between compactified string theories on torus and gauge fields on it. We start from open string theories with background gauge fields and derive partition functions by path integral. Since the effects of background fields and compactification correlate only through string zero modes, we investigate these zero modes. From this point of view, we discuss the Wilson loop mechanism at finite temperature. For the closed string, only a few comments are mentioned.
Rotation Sets of Billiards with N Obstacles on a Torus
Alsheekhhussain, Zainab
2016-01-01
For billiards with $N$ obstacles on a torus, we study the behavior of specific kind of its trajectories, \\emph{the so called admissible trajectories}. Using the methods developed in \\cite{1}, we prove that the \\emph{admissible rotation set} is convex, and the periodic trajectories of admissible type are dense in the admissible rotation set. In addition, we show that the admissible rotation set is a proper subset of the general rotation set.
Torsion Points on an Algebraic Subset of an Affine Torus
Hironaka, E
1996-01-01
Work of Laurent and Sarnak, following a conjecture of Lang, shows that the number of torsion points of order n on an algebraic subset of an affine complex torus is polynomial periodic. In this paper, we find bounds on the degree and period of this number as a function of n. Some examples, including the number of n torsion points on Fermat curves, are computed to illustrate the methods.
Recent results in the Los Alamos compact torus program
Energy Technology Data Exchange (ETDEWEB)
Tuszewski, M.; Armstrong, W.T.; Barnes, C.W.
1983-01-01
A Compact Toroid is a toroidal magnetic-plasma-containment geometry in which no conductors or vacuum-chamber walls pass through the hole in the torus. Two types of compact toroids are studied experimentally and theoretically at Los Alamos: spheromaks that are oblate in shape and contain both toroidal and poloidal magnetic fields, and field-reversed configurations (FRC) that are very prolate and contain poloidal field only.
The torus and the Klein Bottle amplitude of permutation orbifolds
Kadar, Z
2000-01-01
The torus and the Klein bottle amplitude coefficients are computed in permutation orbifolds of RCFT-s in terms of the same quantities in the original theory and the twist group. An explicit expression is presented for the number of self conjugate primaries in the orbifold as a polynomial of the total number of primaries and the number of self conjugate ones in the parent theory. The formulae in the $Z_2$ orbifold illustrate the general results.
Io plasma torus ion composition: Voyager, Galileo, and Cassini
Nerney, Edward G.; Bagenal, Fran; Steffl, Andrew J.
2017-01-01
The Io torus produces ultraviolet emissions diagnostic of plasma conditions. We revisit data sets obtained by the Voyager 1, Galileo, and Cassini missions at Jupiter. With the latest version (8.0) of the CHIANTI atomic database we analyze UV spectra to determine ion composition. We compare ion composition obtained from observations from these three missions with a theoretical model of the physical chemistry of the torus by Delamere et al. (2005). We find ion abundances from the Voyager data similar to the Cassini epoch, consistent with the dissociation and ionization of SO2, but with a slightly higher average ionization state for sulfur, consistent with the higher electron temperature measured by Voyager. This reanalysis of the Voyager data produces a much lower oxygen:sulfur ratio than earlier analysis by Shemansky (1988), which was also reported by Bagenal (1994). We derive fractional ion compositions in the center of the torus to be S+/Ne 5%, S++/Ne 20%, S+++/Ne 5%, O+/Ne 20%, O++/Ne 3%, and Σ(On+)/Σ(Sn+) 0.8, leaving about 10-15% of the charge as protons. The radial profile of ion composition indicates a slightly higher average ionization state, a modest loss of sulfur relative to oxygen, and Σ(On+)/Σ(Sn+) 1.2 at about 8 RJ, beyond which the composition is basically frozen in. The Galileo observations of UV emissions from the torus suggest that the composition in June 1996 may have comprised a lower abundance of oxygen than usual, consistent with observations made at the same time by the EUVE satellite.
Gauge Theory of the Generalized Symmetry on the Torus Membrane
Institute of Scientific and Technical Information of China (English)
ZHAO WeiZhong; WANG Hong; ZHANG Jun
2001-01-01
The SDIFF(T2)local-generalized Kac-Moody G(T2) symmetry is an infinite-dimensional group on the torus membrane, whose Lie algebra is the semi-direct sum of the SDIFF(T2)local algebra and the generalized KacMoody algebra g(T2). In this paper, we construct the linearly realized gauge theory of the SDIFF(T2)loc1al-generalized Kac-Moody G(T2) symmetry.``
Relaxed states in electron-depleted electronegative dusty plasmas with two-negative ion species
Iqbal, M.; Iqbal
2014-02-01
The relaxation of an electron-depleted electronegative dusty plasma with two-negative ions is investigated. When the ratio of canonical vorticities to corresponding flows of all the plasma species is the same and all inertial and non-inertial forces are present, the relaxed state appears as a double Beltrami magnetic field which is the superposition of two force-free relaxed states. The numerical results show that highly diamagnetic relaxed magnetic fields can be obtained by controlling the flow and vorticities through a single Beltrami parameter. The study is useful to investigate the creation of diamagnetic plasma configurations which are considered to be very important in the context of nuclear fusion.
Dusty Relic to Shining Treasure: Embedded in a Multicultural Environment
Avery, Beth Fuseler; Batman, Cindy
2014-01-01
Far from being dusty old relics who are guardians of the book, embedded librarians need to be proactively leading students through the digital maze of the virtual library. Working with students more than 7,000 miles away changed perceptions of how to teach and learn, and how people interact online. We will share how as embedded librarians we…
Complex and Dusty Plasmas From Laboratory to Space
Fortov, Vladimir E
2009-01-01
Dusty or complex plasmas are plasmas containing solid or liquid charged particles referred to as dust. Naturally occurring in space, on earth dust plays a key role in plasma applications associated with etching technologies in microelectronics. International in scope, this volume covers theoretical and application research.
Does the Decay Wave Propagate Forwards in Dusty Plasmas?
Institute of Scientific and Technical Information of China (English)
谢柏松
2002-01-01
The decay interaction of the ion acoustic wave in a dusty plasma with variable-charge dust grains is studied.Even if strong charging relaxation for dust grains and the short wavelength regime for ion waves are included, it is found that the decay wave must be backward propagating.
Dustiness of 14 carbon nanotubes using the vortex shaker method
Dazon, Claire; Witschger, Olivier; Bau, Sébastien; Payet, Raphaël; Beugnon, Karine; Petit, Geneviève; Garin, Thibaut; Martinon, Laurent
2017-06-01
The handling of carbon nanotube (CNT) powders is a plausible scenario during the course of the CNT life-cycle. However, related exposure data remain limited. In this context, information about the dustiness of CNT is therefore of great interest, for example for control banding or exposure modelling. Here, we investigate the dustiness of fourteen CNT powders using the Vortex Shaker (VS) method. The central component of the VS method is a stainless steel cylindrical tube, continuously shaken in a circular orbital motion, in which a small volume (0.5 cm3) of the powder to be tested is placed. All samples were obtained through the NANoREG Nanomaterials Information and Web-Order system. The test procedure that we have developed is based on four principal components: (i) a respirable cyclone for gravimetric sampling, (ii) a CPC as a reference instrument for number concentration measurement, (iii) an MPS for collection of particles for EM observations/analysis, and (iv) an ELPI for size-resolved aerosol measurement. In this paper, the data were evaluated using two parameters: (i) the mass-based dustiness index in the respirable fraction; and (ii) the number-based dustiness index in the respirable fraction. The results indicate that the method leads to relatively accurate mass- and number-based dustiness indices. The indices obtained span wide ranges, of 2 and 3 orders of magnitude variation for mass and number respectively, suggesting a corresponding significant difference in terms of potential exposure. EM observations reveal that airborne CNTs are mostly released as bundles of different shapes ranging from a few tens of nanometers up to tens of micrometers in size.
Compact Torus Accelerator Driven Inertial Confinement Fusion Power Plant HYLIFE-CT
Energy Technology Data Exchange (ETDEWEB)
Logan, B G; Moir, R W; Tabak, M; Bieri, R L; Hammer, J H; Hartman, C W; Hoffman, M A; Leber, R L; Petzoldt, R W; Tobin, M T
2005-03-30
A Compact Torus Accelerator (CTA) is used to accelerate a Compact Torus (CT) to 35 MJ kinetic energy which is focused to a 20 mm diameter where its kinetic energy is converted to a shaped x-ray pulse of 30 MJ. The capsule yield with a prescribed radiation profile is calculated to be (gain 60 times 30 MJ) 1.8 GJ. Schemes for achieving this profile are described. The CT is accelerated in a length of 30 m within an annulus of 150 mm ID and 300 mm OD where the maximum magnetic field is 28 T. A 2.5 m conical taper reduces the mean diameter of the CT from 225 mm to 20 mm. The conical section is made out of solid Li{sub 2}BeF{sub 4}. The target with its frozen conical guide section is accurately placed at the end of the accelerator about once per second. The reactor called HYLIFE uses liquid jets to attenuate blast effects including shrapnel from the shattered conical guide section and radiation so that the vessel is expected to last 30 years. The calculated cost of electricity is estimated (in constant 1988 dollars) to be about 4.8 cents/kW {center_dot} h compared to the future cost of nuclear and coal of 4.3 to 5.8 cents/kW {center_dot} h. The CT driver contributes 17% to the cost of electricity. Present CT's make 2 x 10{sup 8} W/cm{sup 2}; the goal of experiments in progress is 10{sup 11} W/cm{sup 2} with further modifications to allow 10{sup 12}W/cm{sup 2}, whereas the reactor requires 10{sup 15} W/cm{sup 2} in a shaped pulse.
Energy Technology Data Exchange (ETDEWEB)
Sazonov, S.; Churazov, E.; Krivonos, R.; Revnivtsev, M.; Sunyaev, R.; Vikhlinin, A. [Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow 117997 (Russian Federation); Willner, S. P.; Goulding, A. D.; Jones, C.; Murray, S. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hickox, R. C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Gorjian, V.; Werner, M. W. [Jet Propulsion Laboratory, California Institute of Technology, MS 169-327, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Forman, W. R. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany)
2012-10-01
We estimate the relative contributions of the supermassive black hole (SMBH) accretion disk, corona, and obscuring torus to the bolometric luminosity of Seyfert galaxies, using Spitzer mid-infrared (MIR) observations of a complete sample of 68 nearby active galactic nuclei (AGNs) from the INTEGRAL all-sky hard X-ray (HX) survey. This is the first HX-selected (above 15 keV) sample of AGNs with complementary high angular resolution, high signal-to-noise, MIR data. Correcting for the host galaxy contribution, we find a correlation between HX and MIR luminosities: L{sub 15{mu}m}{proportional_to}L{sup 0.74{+-}0.06}{sub HX}. Assuming that the observed MIR emission is radiation from an accretion disk reprocessed in a surrounding dusty torus that subtends a solid angle decreasing with increasing luminosity (as inferred from the declining fraction of obscured AGNs), the intrinsic disk luminosity, L{sub Disk}, is approximately proportional to the luminosity of the corona in the 2-300 keV energy band, L{sub Corona}, with the L{sub Disk}/L{sub Corona} ratio varying by a factor of 2.1 around a mean value of 1.6. This ratio is a factor of {approx}2 smaller than for typical quasars producing the cosmic X-ray background. Therefore, over three orders of magnitude in luminosity, HX radiation carries a large, and roughly comparable, fraction of the bolometric output of AGNs. We estimate the cumulative bolometric luminosity density of local AGNs at {approx}(1-3) Multiplication-Sign 10{sup 40} erg s{sup -1} Mpc{sup -3}. Finally, the Compton temperature ranges between kT{sub c} Almost-Equal-To 2 and Almost-Equal-To 6 keV for nearby AGNs, compared to kT{sub c} Almost-Equal-To 2 keV for typical quasars, confirming that radiative heating of interstellar gas can play an important role in regulating SMBH growth.
Observational Constraints on a Pluto Torus of Circumsolar Neutral Gas
Hill, M. E.; Kollmann, P.; McNutt, R. L., Jr.; Smith, H. T.; Bagenal, F.; Brown, L. E.; Elliott, H. A.; Haggerty, D. K.; Horanyi, M.; Krimigis, S. M.; Kusterer, M. B.; Lisse, C. M.; McComas, D. J.; Piquette, M. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Vandegriff, J. D.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, S. A.
2015-12-01
We present the concept of a neutral gas torus surrounding the Sun, aligned with Pluto's orbit, and place observational constraints based primarily on comparison of New Horizons (NH) measurements with a 3-D Monte Carlo model adapted from analogous satellite tori surrounding Saturn and Jupiter. Such a torus, or perhaps partial torus, should result from neutral N2 escaping from Pluto's exosphere. Unlike other more massive planets closer to the Sun, neutrals escape Pluto readily owing, e.g., to the high thermal speed relative to the escape velocity. Importantly, escaped neutrals have a long lifetime due to the great distance from the Sun, ~100 years for photoionization of N2 and ~180 years for photoionization of N, which results from disassociated N2. Despite the lengthy 248-year orbit, these long e-folding lifetimes may allow an enhanced neutral population to form an extended gas cloud that modifies the N2 spatial profile near Pluto. These neutrals are not directly observable by NH but once ionized N2+ or N+ are picked up by the solar wind, reaching ~50 keV, making these pickup ions (PUIs) detectable by NH's Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument. PEPSSI observations analyzed to date may constrain the N2 density; the remaining ~95% of the encounter data, scheduled for downlink in August along with similarly anticipated data from the Solar Wind Around Pluto (SWAP) experiment, should help determine the Pluto outgassing rates. Measurements from SWAP include the solar wind speed, a quantity that greatly enhances PUI studies by enabling us to directly account for the PUI distribution's sensitive dependence on plasma speed. Note that anomalous cosmic ray Si observed at Voyager is overabundant by a factor of ~3000 relative to interstellar composition. This might be related to "outer source" PUIs, but the fact that N2 and Si are indistinguishable in many instruments could mean that N2 is actually driving this apparent Si discrepancy.
2011-03-01
This image of NGC 247, taken by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile, reveals the fine details of this highly inclined spiral galaxy and its rich backdrop. Astronomers say this highly tilted orientation, when viewed from Earth, explains why the distance to this prominent galaxy was previously overestimated. The spiral galaxy NGC 247 is one of the closest spiral galaxies of the southern sky. In this new view from the Wide Field Imager on the MPG/ESO 2.2-metre telescope in Chile large numbers of the galaxy's component stars are clearly resolved and many glowing pink clouds of hydrogen, marking regions of active star formation, can be made out in the loose and ragged spiral arms. NGC 247 is part of the Sculptor Group, a collection of galaxies associated with the Sculptor Galaxy (NGC 253, also shown in eso0902 and eso1025). This is the nearest group of galaxies to our Local Group, which includes the Milky Way, but putting a precise value on such celestial distances is inherently difficult. To measure the distance from the Earth to a nearby galaxy, astronomers have to rely on a type of variable star called a Cepheid to act as a distance marker. Cepheids are very luminous stars, whose brightness varies at regular intervals. The time taken for the star to brighten and fade can be plugged into a simple mathematical relation that gives its intrinsic brightness. When compared with the measured brightness this gives the distance. However, this method isn't foolproof, as astronomers think this period-luminosity relationship depends on the composition of the Cepheid. Another problem arises from the fact that some of the light from a Cepheid may be absorbed by dust en route to Earth, making it appear fainter, and therefore further away than it really is. This is a particular problem for NGC 247 with its highly inclined orientation, as the line of sight to the Cepheids passes through the galaxy's dusty disc. However, a
Configuration spaces of an embedding torus and cubical spaces
Jourdan, Jean-Philippe
2006-01-01
For a smooth manifold M obtained as an embedding torus, A U Cx[-1,1], we consider the ordered configuration space F_k(M) of k distinct points in M. We show that there is a homotopical cubical resolution of F_k(M) defined from the configuration spaces of A and C. From it, we deduce a universal method for the computation of the pure braid groups of a manifold. We illustrate the method in the case of the Mobius band.
Free compact boson on branched covering of the torus
Directory of Open Access Journals (Sweden)
Feihu Liu
2017-08-01
Full Text Available We have studied the partition function of a free compact boson on a n-sheeted covering of torus gluing along m branch cuts. It is interesting because when the branched cuts are chosen to be real, the partition function is related to the n-th Rényi entanglement entropy of m disjoint intervals in a finite system at finite temperature. After proposing a canonical homology basis and its dual basis of the covering surface, we find that the partition function can be written in terms of theta functions.
Punctured torus groups and 2-bridge knot groups
Akiyoshi, Hirotaka; Wada, Masaaki; Yamashita, Yasushi
2007-01-01
This monograph is Part 1 of a book project intended to give a full account of Jorgensen's theory of punctured torus Kleinian groups and its generalization, with application to knot theory. Although Jorgensen's original work was not published in complete form, it has been a source of inspiration. In particular, it has motivated and guided Thurston's revolutionary study of low-dimensional geometric topology. In this monograph, we give an elementary and self-contained description of Jorgensen's theory with a complete proof. Through various informative illustrations, readers are naturally led to an intuitive, synthetic grasp of the theory, which clarifies how a very simple fuchsian group evolves into complicated Kleinian groups.
Multiple Chern-Simons fields on a torus
Wesolowski, D J; Ho, C L
1994-01-01
Intertwined multiple Chern-Simons gauge fields induce matrix statistics among particles. We analyse this theory on a torus, focusing on the vacuum structure and the Hilbert space. The theory can be mimicked, although not completely, by an effective theory with one Chern-Simons gauge field. The correspondence between the Wilson line integrals, vacuum degeneracy and wave functions for these two theories are discussed. Further, it is obtained in both of these cases that the two total momenta and Hamiltonian commute only in the physical Hilbert space.
General Equilibrium Property of Spherical Torus Configurations with Large Triangularity
Institute of Scientific and Technical Information of China (English)
SHIBingren
2003-01-01
In magnetic fusion research, two sorts of axi-symmetric toroidal equilibrium configuration are mostly interested. One is the conventional tokamak that has an aspect ratio 2. 8torus (the ST configuration) with A≤1.4.For tokamaks, it is generally observed that equilibrium configurations with large triangular deformation usually has the merit of stabilizing higher beta plasma and better confinement scaling so that higher βN/li value can be attained. This was also verified theoretically in the ballooning mode analysis.
The torus parametrization of quasiperiodic LI-classes
Baake, M; Pleasants, P A B
2002-01-01
The torus parametrization of quasiperiodic local isomorphism classes is introduced and used to determine the number of elements in such a class with special symmetries or inflation properties. The method is explained in an illustrative fashion for some widely used tiling classes with golden mean rescaling, namely for the Fibonacci chain (1D), the triangle and Penrose patterns (2D) and for Kramer's and Danzer's icosahedral tilings (3D). We obtain a rather complete picture of the orbit structure within these classes, but discuss also various general results.
Legendrian and transverse cables of positive torus knots
DEFF Research Database (Denmark)
Etnyre, John; LaFountain, Douglas; Tosun, Bülent
2012-01-01
In this paper we classify Legendrian and transverse knots in the knot types obtained from positive torus knots by cabling. This classification allows us to demonstrate several new phenomena. Specifically, we show there are knot types that have non-destabilizable Legendrian representatives whose...... Thurston-Bennequin invariant is arbitrarily far from maximal. We also exhibit Legendrian knots requiring arbitrarily many stabilizations before they become Legendrian isotopic. Similar new phenomena are observed for transverse knots. To achieve these results we define and study "partially thickenable" tori...
Invariant sets for discontinuous parabolic area-preserving torus maps
Ashwin, P; Nishikawa, T; Zyczkowski, K; Ashwin, Peter; Fu, Xin-Chu; Nishikawa, Takashi; Zyczkowski, Karol
1999-01-01
We analyze a class of piecewise linear parabolic maps on the torus, namely those obtained by considering a linear map with double eigenvalue one and taking modulo one in both components. We show that within this two parameter family of maps, the set of noninvertible maps is open and dense. For certain cases (where the entries in the matrix are rational) we show that the maximal invariant set has positive Lebesgue measure and give bounds on the measure. For certain examples we find expressions for the measure of the invariant set.
Final report on the LLNL compact torus acceleration project
Energy Technology Data Exchange (ETDEWEB)
Eddleman, J.; Hammer, J.; Hartman, C.; McLean, H.; Molvik, A.
1995-03-19
In this report, we summarize recent work at LLNL on the compact torus (CT) acceleration project. The CT accelerator is a novel technique for projecting plasmas to high velocities and reaching high energy density states. The accelerator exploits magnetic confinement in the CT to stably transport plasma over large distances and to directed kinetic energies large in comparison with the CT internal and magnetic energy. Applications range from heating and fueling magnetic fusion devices, generation of intense pulses of x-rays or neutrons for weapons effects and high energy-density fusion concepts.
p-adic string compactified on a torus
Energy Technology Data Exchange (ETDEWEB)
Chekhov, L.; Zinoviev, Yu. (Steklov (V.A.) Inst. of Mathematics, Moscow (USSR))
1990-10-01
The open p-adic string world sheet is a coset space F = T/{Gamma}, where T is the Bruhat-Tits tree for the p-adic linear group GL(2,Q{sub p}) and c PGL(2,Q{sub p})is some Schottky group. The string dynamics is governed by the local action on F, with the fields taking values in a compact groupg G. We find the correlation functions and partition functions for the p-adic string surfaces of arbitrary genus and G = U(1){sup xD} (D-dimensional torus). (orig.).
Infrared Interferometry and AGNs: Parsec-scale Disks and Dusty Outflows
Burtscher, Leonard; Jaffe, Walter; Kishimoto, Makoto; Lopez-Gonzaga, Noel; Meisenheimer, Klaus; Tristram, Konrad R W
2016-01-01
The "torus" is the central element of the most popular theory unifying various classes of AGNs, but it is usually described as "putative" because it has not been imaged yet. Since it is too small to be resolved with single-dish telescopes, one can only make indirect assumptions about its structure using models. Using infrared interferometry, however, we were able to resolve the circum-nuclear dust distributions for several nearby AGNs and achieved constraints on some further two dozen sources. We discovered circum-nuclear dust on parsec scales in all sources and, in two nearby sources, were able to dissect this dust into two distinct components. The compact component, a very thin disk, appears to be connected to the maser disk and the extended one, which is responsible for most of the mid-IR flux, is oriented perpendicularly to the circum-nuclear gas disks. What may come as a surprise when having in mind the standard unification cartoon actually connects well to observations on larger scales. Optically thin d...
Electrostatic Modes of Dusty Plasmas in a Uniform Magnetic Field
Institute of Scientific and Technical Information of China (English)
王晓钢; 王春华
2002-01-01
Electrostatic dusty plasma waves in a uniform magnetic field are studied. Unless the magnetic field is extremely strong, the dust particles can hardly be magnetized, while however,electrons and ions are easily done so. Electrostatic modes in such dusty plasmas can then be investigated by making use of the "moderately magnetized" assumption of magnetized electrons and ions, and unmagnetized dust particles. In a high frequency range, due to the existence of dust component, both frequencies of Langmuir waves (parallel to the magnetic field) and upper hybrid waves (perpendicular to the field)are reduced. In the frequency range of ion waves, besides the effect on dust-ion-acoustic waves propagating parallel to the magnetic field, the frequency of ion cyclotron waves perpendicular to the magnetic field is also enhanced. In a very low dust frequency range, we find an "ion-cyclotrondust-acoustic" mode propagating across the field line with a frequency even slower than dust acoustic waves.
Electrostatic twisted modes in multi-component dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Ayub, M. K. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Pohang University of Sciences and Technology, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Ali, S. [National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Ikram, M. [Department of Physics, Hazara University, Mansehra 21300 (Pakistan)
2016-01-15
Various electrostatic twisted modes are re-investigated with finite orbital angular momentum in an unmagnetized collisionless multi-component dusty plasma, consisting of positive/negative charged dust particles, ions, and electrons. For this purpose, hydrodynamical equations are employed to obtain paraxial equations in terms of density perturbations, while assuming the Gaussian and Laguerre-Gaussian (LG) beam solutions. Specifically, approximated solutions for potential problem are studied by using the paraxial approximation and expressed the electric field components in terms of LG functions. The energy fluxes associated with these modes are computed and corresponding expressions for orbital angular momenta are derived. Numerical analyses reveal that radial/angular mode numbers as well as dust number density and dust charging states strongly modify the LG potential profiles attributed to different electrostatic modes. Our results are important for understanding particle transport and energy transfer due to wave excitations in multi-component dusty plasmas.
Growth of ordered dusty structures in the glow discharge
Khakhaev, A; Khakhaev, Anatoly; Podriadtchikov, Sergey
2004-01-01
In plasma of direct-current glow discharge the dependence of ordered dusty structure volume, shape and density on plasma conditions were investigated. The structure is formed in a field of volume charge. In experimental investigations we used the aluminum oxide macroparticles with diameter up to 60 microns (size distribution function was not determined). Discharge tube was established vertically, has an internal diameter 2.6 cm and space gap between electrodes 45 cm. Particles were injected from the top end of the discharge tube into the plasma of spectral purity neon. Repeatability of randomized experiment results was better than 5% of the measured values. The areas of existence of various dusty ordered structures and their dependence on physical conditions in plasma (discharge current and pressure) were determined. When the interparticle distance in the structure is constant and particle positions have good time stability this structure was defined like "plasma crystal". Otherwise, we observed process of th...
Low frequency waves in streaming quantum dusty plasmas
Rozina, Ch.; Jamil, M.; Khan, Arroj A.; Zeba, I.; Saman, J.
2017-09-01
The influence of quantum effects on the excitation of two instabilities, namely quantum dust-acoustic and quantum dust-lower-hybrid waves due to the free streaming of ion/dust particles in uniformly magnetized dusty plasmas has been investigated using a quantum hydrodynamic model. We have obtained dispersion relations under some particular conditions applied on streaming ions and two contrastreaming dust particle beams at equilibrium and have analyzed the growth rates graphically. We have shown that with the increase of both the electron number density and the streaming speed of ion there is enhancement in the instability due to the fact that the dense plasma particle system with more energetic species having a high speed results in the increase of the growth rate in the electrostatic mode. The application of this work has been pointed out for laboratory as well as for space dusty plasmas.
Surface waves in the magnetized, collisional dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Pandey, B. P. [Department of Physics, Astronomy and Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney NSW 2109 (Australia); Vladimirov, S. V. [School of Physics, The University of Sydney, Sydney NSW 2006 (Australia); Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan); Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 (Russian Federation); Ishihara, O. [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)
2013-10-15
The properties of the low frequency surface waves in inhomogeneous, magnetized collisional complex dusty plasma are investigated in this work. The inhomogeneity is modelled by the two distinct regions of the dusty medium with different dust densities. The external magnetic field is assumed to be oriented along the interface dividing the two medium. It is shown that the collisional momentum exchange that is responsible for the relative drift between the plasma particles affects the propagation of the surface waves in the complex plasma via the Hall drift of the magnetic fluctuations. The propagation properties of the sausage and kink waves depend not only on the grain charge and size distribution but also on the ambient plasma thermal conditions.
Unsteady Viscous Dissipative Dusty Nanofluid Flow Over a Vertical Plate
Directory of Open Access Journals (Sweden)
D.R.V.S.R.K. Sastry
2016-10-01
Full Text Available The flow past an infinite vertical isothermal plate started impulsively in its own plane in a viscous incompressible two-phase nanofluid has been considered by taking into account the viscous dissipative heat. Two nano particles Copper (Cu and Alumina (Al2O3 are submerged in a base fluid, Water (H20. The coupled non-linear partial differential equations which govern the flow are solved for nanofluid and dust particle phases by finite difference method. The velocity and temperature fields have been shown graphically for various parameters. Here Grashof number, (Gr being positive (cooling of the plate for dusty air. Also the effects of Eckert number on heat transfer and skin friction coefficient for various parameters are represented graphically. It is observed that dusty nanofluid enhances both skin friction and heat transfer rate in the case of cooling.
Stability of Rayleigh-Taylor Vortices in Dusty Plasma
Institute of Scientific and Technical Information of China (English)
MA Jun; CHEN Yin-Hua; GAN Bao-Xia; WANG Fei-Hu; WANG Dong
2006-01-01
@@ The evolution of Rayleigh-Taylor mode in dusty plasma with vortex-flow is investigated. Based on fluid theory and Bayly's method, we derive the coupling equations describing the Rayleigh-Taylor mode in the core of vortex,and research the evolution characteristics of the perturbation amplitude with time numerically. It is shown that the eccentric of vortex and the content of dust have considerable effects on the amplitude evolutions.
Shock wave diffraction and reflection around a dusty square cavity
Institute of Scientific and Technical Information of China (English)
王柏懿; 王超; 戚隆溪
2001-01-01
The diffraction and reflection of planar shock wave around a dusty square cavity is investigated nuerically, which is embedded in the flat bottom surface of a two-dimensional channel, and the induced gas-particle twophase flow. The wave patterns at different times are obtained for three different values of the particle diameter. The computational results show that the existence of particles affects appreciably the shock wave diffraction and cavity flow.
Intervascular pit membranes with a torus in the wood of Ulmus (Ulmaceae) and related genera
Jansen, S.; Choat, B.; Vinckier, S.; Lens, F.; Schols, P.; Smets, E.
2004-01-01
• The distribution of intervascular pit membranes with a torus was investigated in juvenile wood samples of 19 species of Ulmus and seven related genera. • A staining solution of safranin and alcian blue (35 : 65) was recommended to distinguish torus-bearing pit membranes using light microscopy. • I
Modeling physical chemistry of the Io plasma torus in two dimensions
Copper, M.; Delamere, P. A.; Overcast-Howe, K.
2016-07-01
Periodicities in the Io plasma illustrate the rich complexity of magnetosphere-ionosphere coupling in space plasmas. The confounding System IV period (slower than the rotation of Jupiter's magnetic field ≡ System III) remains a mystery of the torus. Common to both System III and IV are modulations of the superthermal electron population. The small fraction (<1%) of hot electrons plays a vital role in torus physical and chemical properties, modulating the abundance and temperature of ion species. Building on previous models of torus physical chemistry, we have developed a two-dimensional model that includes azimuthal and radial transport (diffusion equation) while averaging chemical processes in latitude. This paper presents initial results of the model, demonstrating the role of hot electrons in forming a single-peaked torus structure. The effect of azimuthal shear is investigated as plasma is transported radially outward, showing how the torus properties evolve during transport from a chemically dominated regime (inner torus) to a transport dominated regime (outer torus). Surprisingly, we find that hot electron populations influence torus properties at all radial distances. While many of our results are preliminary, suggestions for future modeling experiments are suggested to provide additional insight into the origin of the ubiquitous superthermal electrons.
3D couette flow of dusty fluid with transpiration cooling
Institute of Scientific and Technical Information of China (English)
GOVINDARAJAN A.; RAMAMURTHY V.; SUNDARAMMAL K.
2007-01-01
The couette dusty flow between two horizontal parallel porous flat plates with transverse sinusoidal injection of the dusty fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion was analyzed. Due to this type of injection velocity the dusty flow becomes 3D. Perturbation method is used to obtain the expressions for the velocity and temperature fields of both the fluid and dust. It was found that the velocity profiles of both the fluid and dust in the main flow direction decrease with the increase of the mass concentration of the dust panicles, and those in cross flow direction increase with an increase in the mass concentration of the dust particles up to the middle of the channel and thereafter decrease with increase in mass concentration of the dust particles. The skin friction components Tx and Tz in the main flow and transverse directions respectively increase with an increase in the mass concentration of the dust particles (or) injection parameter. The heat transfer coefficient decreases with the increase of the injection parameter and increases with the increase in the mass concentration of the dust particles.
FDTD Simulation on Terahertz Waves Propagation Through a Dusty Plasma
Wang, Maoyan; Zhang, Meng; Li, Guiping; Jiang, Baojun; Zhang, Xiaochuan; Xu, Jun
2016-08-01
The frequency dependent permittivity for dusty plasmas is provided by introducing the charging response factor and charge relaxation rate of airborne particles. The field equations that describe the characteristics of Terahertz (THz) waves propagation in a dusty plasma sheath are derived and discretized on the basis of the auxiliary differential equation (ADE) in the finite difference time domain (FDTD) method. Compared with numerical solutions in reference, the accuracy for the ADE FDTD method is validated. The reflection property of the metal Aluminum interlayer of the sheath at THz frequencies is discussed. The effects of the thickness, effective collision frequency, airborne particle density, and charge relaxation rate of airborne particles on the electromagnetic properties of Terahertz waves through a dusty plasma slab are investigated. Finally, some potential applications for Terahertz waves in information and communication are analyzed. supported by National Natural Science Foundation of China (Nos. 41104097, 11504252, 61201007, 41304119), the Fundamental Research Funds for the Central Universities (Nos. ZYGX2015J039, ZYGX2015J041), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120185120012)
Langmuir probe in collisionless and collisional plasma including dusty plasma
Bose, Sayak; Kaur, Manjit; Chattopadhyay, P. K.; Ghosh, J.; Saxena, Y. C.; Pal, R.
2017-04-01
Measurements of local plasma parameters in dusty plasma are crucial for understanding the physics issues related to such systems. The Langmuir probe, a small electrode immersed in the plasma, provides such measurements. However, designing of a Langmuir probe system in a dusty plasma environment demands special consideration. First, the probe has to be miniaturized enough so that its perturbation on the ambient dust structure is minimal. At the same time, the probe dimensions must be such that a well-defined theory exists for interpretation of its characteristics. The associated instrumentation must also support the measurement of current collected by the probe with high signal to noise ratio. The most important consideration, of course, comes from the fact that the probes are prone to dust contamination, as the dust particles tend to stick to the probe surface and alter the current collecting area in unpredictable ways. This article describes the design and operation of a Langmuir probe system that resolves these challenging issues in dusty plasma. In doing so, first, different theories that are used to interpret the probe characteristics in collisionless as well as in collisional regimes are discussed, with special emphasis on application. The critical issues associated with the current-voltage characteristics of Langmuir probe obtained in different operating regimes are discussed. Then, an algorithm for processing these characteristics efficiently in presence of ion-neutral collisions in the probe sheath is presented.
Investigating the Structure of the Windy Torus in Quasars
Gallagher, S C; Abado, M M; Keating, S K
2015-01-01
Thermal mid-infrared emission of quasars requires an obscuring structure that can be modeled as a magneto-hydrodynamic wind in which radiation pressure on dust shapes the outflow. We have taken the dusty wind models presented by Keating and collaborators that generated quasar mid-infrared spectral energy distributions (SEDs), and explored their properties (such as geometry, opening angle, and ionic column densities) as a function of Eddington ratio and X-ray weakness. In addition, we present new models with a range of magnetic field strengths and column densities of the dust-free shielding gas interior to the dusty wind. We find this family of models -- with input parameters tuned to accurately match the observed mid-IR power in quasar SEDs -- provides reasonable values of the Type 1 fraction of quasars and the column densities of warm absorber gas, though it does not explain a purely luminosity-dependent covering fraction for either. Furthermore, we provide predictions of the cumulative distribution of E(B-V...
Fabricating of full denture acrylic protheses with palatine torus
Directory of Open Access Journals (Sweden)
Ima Hariyati
2016-06-01
Full Text Available Full denture acrylic protheses can substitute all maxillary or mandibulary teeth naturally. The objective of fabricating full denture protheses is to substitute the tissue lost that was occupied by teeth or connective tissue before ward. This is a case of a 43 year old female with lost of all her upper and lower teeth. At the maxilla there is a palatine torus spreading along the midline with 25 mm length, 10 mm width and 6mm height. She has never worn prothese before. The process of full denture protheses fabrication were carried out in several steps, starting from making anatomical impression to get study model, making of individual stock tray, making functional impression to get working model, choosing the design, making of midline, making of bite rim, inserting the model on articulator, preparing artificial teeth arrangement, fitting the wax, countoring wax, flasking, boiling out, packing, curing, deflasking, finishing, polishing and inserting the protheses. The process of this full denture protheses fabrication used tin foil as reducer to prevent overpressure of the tissue around the thin torus area so the prothesis will be more comfortable for the patient. The result was the protheses can be used by the patient, nicely and comfortably.
Divertor Heat Flux Mitigation in the National Spherical Torus Experiment
Energy Technology Data Exchange (ETDEWEB)
Soukhanovskii, V A; Maingi, R; Gates, D A; Menard, J E; Paul, S F; Raman, R; Roquemore, A L; Bell, M G; Bell, R E; Boedo, J A; Bush, C E; Kaita, R; Kugel, H W; LeBlanc, B P; Mueller, D
2008-08-04
Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly-shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6 MW m{sup -2} to 0.5-2 MW m{sup -2} in small-ELM 0.8-1.0 MA, 4-6 MW neutral beam injection-heated H-mode discharges. A self-consistent picture of outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.
Variation of Inner Radius of Dust Torus in NGC4151
Koshida, Shintaro; Kobayashi, Yukiyasu; Minezaki, Takeo; Sakata, Yu; Sugawara, Shota; Enya, Keigo; Suganuma, Masahiro; Tomita, Hiroyuki; Aoki, Tsutomu; Peterson, Bruce A
2009-01-01
The long-term optical and near infrared monitoring observations for a type 1 act ive galactic nucleus NGC 4151 were carried out for six years from 2001 to 2006 b y using the MAGNUM telescope, and delayed response of flux variations in the $K(2.2\\mu m)$ band to those in the $V(0.55\\mu m)$ band was clearly detected. Based on cross correlation analysis, we precisely measured a lag time $\\Delta t$ for eight separate periods, and we found that $\\Delta t$ is not constant changing be tween 30 and 70 days during the monitoring period. Since $\\Delta t$ is the ligh t travel time from the central energy source out to the surrounding dust torus, this is the first convincing evidence that the inner radius of dust torus did ch ange in an individual AGN. In order to relate such a change of $\\Delta t$ with a change of AGN luminosity $L$, we presented a method of taking an average of th e observed $V$-band fluxes that corresponds to the measured value of $\\Delta t$, and we found that the time-changing track of NGC 4151 in the...
Solitons on Noncommutative Torus as Elliptic Algebras and Elliptic Models
Hou, B Y; Shi, K J; Yue, R H; Hou, Bo-Yu; Peng, Dan-tao; Shi, Kang-Jie; Yue, Rui-Hong
2001-01-01
For the noncommutative torus ${\\cal T}$, in case of the N.C. parameter $\\theta = \\frac{Z}{n}$ and the area of ${\\cal T}$ is an integer, we construct the basis of Hilbert space ${\\cal H}_n$ in terms of $\\theta$ functions of the positions of $n$ solitons. The Wilson loop wrapping the solitons around the torus generates the algebra ${\\cal A}_n$. We find that ${\\cal A}_n$ is isomorphic to the $Z_n \\times Z_n$ Heisenberg group on $\\theta$ functions. We find the explicit form for the solitons local translation operators, show that it is the generators $g$ of an elliptic $su(n)$, which transform covariantly by the global gauge transformation of the Wilson loop in ${\\cal A}_n$. Then by acting on ${\\cal H}_n$ we establish the isomorphism of ${\\cal A}_n$ and $g$. Then it is easy to give the projection operators corresponding to the solitons and the ABS construction for generating solitons. We embed this $g$ into elliptic Gaudin and C.M. models to give the dynamics. For $\\theta$ generic case, we introduce the crossing p...
Engineering design of the National Spherical Torus Experiment
Energy Technology Data Exchange (ETDEWEB)
C. Neumeyer; P. Heitzenroeder; J. Spitzer, J. Chrzanowski; et al
2000-05-11
NSTX is a proof-of-principle experiment aimed at exploring the physics of the ``spherical torus'' (ST) configuration, which is predicted to exhibit more efficient magnetic confinement than conventional large aspect ratio tokamaks, amongst other advantages. The low aspect ratio (R/a, typically 1.2--2 in ST designs compared to 4--5 in conventional tokamaks) decreases the available cross sectional area through the center of the torus for toroidal and poloidal field coil conductors, vacuum vessel wall, plasma facing components, etc., thus increasing the need to deploy all components within the so-called ``center stack'' in the most efficient manner possible. Several unique design features have been developed for the NSTX center stack, and careful engineering of this region of the machine, utilizing materials up to their engineering allowables, has been key to meeting the desired objectives. The design and construction of the machine has been accomplished in a rapid and cost effective manner thanks to the availability of extensive facilities, a strong experience base from the TFTR era, and good cooperation between institutions.
Holographic torus entanglement and its renormalization group flow
Bueno, Pablo; Witczak-Krempa, William
2017-03-01
We study the universal contributions to the entanglement entropy (EE) of 2 +1 -dimensional and 3 +1 -dimensional holographic conformal field theories (CFTs) on topologically nontrivial manifolds, focusing on tori. The holographic bulk corresponds to anti-de Sitter-soliton geometries. We characterize the properties of these regulator-independent EE terms as a function of both the size of the cylindrical entangling region, and the shape of the torus. In 2 +1 dimensions, in the simple limit where the torus becomes a thin one-dimensional ring, the EE reduces to a shape-independent constant 2 γ . This is twice the EE obtained by bipartitioning an infinite cylinder into equal halves. We study the renormalization group flow of γ by defining a renormalized EE that (1) is applicable to general QFTs, (2) resolves the failure of the area law subtraction, and (3) is inspired by the F-theorem. We find that the renormalized γ decreases monotonically at small coupling when the holographic CFT is deformed by a relevant operator for all allowed scaling dimensions. We also discuss the question of nonuniqueness of such renormalized EEs both in 2 +1 dimensions and 3 +1 dimensions.
Long-term dynamical evolution of dusty ejecta from Deimos
Makuch, Martin; Krivov, Alexander V.; Spahn, Frank
2005-04-01
We re-assess expected properties of the presumed dust belt of Mars formed by impact ejecta from Deimos. Previous studies have shown that dynamics of Deimos particles are dominated by two perturbing forces: radiation pressure (RP) and Mars' oblateness (J2). At the same time, they have demonstrated that lifetimes of particles, especially of grains about ten of micrometers in size, may reach more than 104 years. On such timescales, the Poynting-Robertson drag (PR) becomes important. Here we provide a study of the dynamics under the combined action of all three perturbing forces. We show that a PR decay of the semimajor axes leads to an adiabatic decrease of amplitudes and periods of oscillations in orbital inclinations predicted in the framework of the underlying RP+J2 problem. Furthermore, we show that smallest of the long-lived Deimos grains (radius≈5- 10μm) may reach a chaotic regime, resulting in unpredictable and abrupt changes of their dynamics. The particles just above that size ( ≈10- 15μm) should be the most abundant in the Deimos torus. Our dynamical analysis, combined with a more accurate study of the particle lifetimes, provides corrections to earlier predictions about the dimensions and geometry of the Deimos torus. In addition to a population, appreciably inclined and shifted towards the Sun, the torus should contain a more contracted, less asymmetric, and less tilted component between the orbits of Phobos and Deimos.
Superconformal index and 3d-3d correspondence for mapping cylinder/torus
Energy Technology Data Exchange (ETDEWEB)
Gang, Dongmin; Koh, Eunkyung [School of Physics, Korea Institute for Advanced Study,85 Hoegiro, Seoul 130-722 (Korea, Republic of); Lee, Sangmin [Center for Theoretical Physics, Seoul National University,1 Gwanak-ro, Seoul 151-747 (Korea, Republic of); Department of Physics and Astronomy, Seoul National University,1 Gwanak-ro, Seoul 151-747 (Korea, Republic of); College of Liberal Studies, Seoul National University,1 Gwanak-ro, Seoul 151-742 (Korea, Republic of); Park, Jaemo [Department of Physics, POSTECH,77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Postech Center for Theoretical Physics (PCTP), Postech,77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of)
2014-01-15
We probe the 3d-3d correspondence for mapping cylinder/torus using the superconformal index. We focus on the case when the fiber is a once-punctured torus (Σ{sub 1,1}). The corresponding 3d field theories can be realized using duality domain wall theories in 4d N=2{sup ∗} theory. We show that the superconformal indices of the 3d theories are the SL(2,ℂ) Chern-Simons partition function on the mapping cylinder/torus. For the mapping torus, we also consider another realization of the corresponding 3d theory associated with ideal triangulation. The equality between the indices from the two descriptions for the mapping torus theory is reduced to a simple basis change of the Hilbert space for the SL(2,ℂ) Chern-Simons theory on ℝ×Σ{sub 1,1}.
Dan, Li; Guo, Li-Xin; Li, Jiang-Ting; Chen, Wei; Yan, Xu; Huang, Qing-Qing
2017-09-01
The expression of complex dielectric permittivity for non-magnetized fully ionized dusty plasma is obtained based on the kinetic equation in the Fokker-Planck-Landau collision model and the charging equation of the statistical theory. The influences of density, average size of dust grains, and balanced charging of the charge number of dust particles on the attenuation properties of electromagnetic waves in fully ionized dusty plasma are investigated by calculating the attenuation constant. In addition, the attenuation characteristics of weakly ionized and fully ionized dusty plasmas are compared. Results enriched the physical mechanisms of microwave attenuation for fully ionized dusty plasma and provide a theoretical basis for future studies.
Self-diffusion in a stochastically heated two-dimensional dusty plasma
Sheridan, T. E.
2016-09-01
Diffusion in a two-dimensional dusty plasma liquid (i.e., a Yukawa liquid) is studied experimentally. The dusty plasma liquid is heated stochastically by a surrounding three-dimensional toroidal dusty plasma gas which acts as a thermal reservoir. The measured dust velocity distribution functions are isotropic Maxwellians, giving a well-defined kinetic temperature. The mean-square displacement for dust particles is found to increase linearly with time, indicating normal diffusion. The measured diffusion coefficients increase approximately linearly with temperature. The effective collision rate is dominated by collective dust-dust interactions rather than neutral gas drag, and is comparable to the dusty-plasma frequency.
Microbial dustiness and particle release of different biofuels
Energy Technology Data Exchange (ETDEWEB)
Madsen, A. M.; Schneider, T. [National Institute of Occupational Health, Lerse Parkalle 104, DK-2100 Copenhagen, (Denmark); Martensson, L. [School of Engineering, Kristianstad University, S-291 88 Kristianstad, (Denmark); Larsson, L. [Department of Medical Microbiology, Dermatology and Infection, University of Lund, Solva Gatan 23, S-22362 Lund, (Sweden)
2004-07-01
Exposure to organic dust originating from biofuels can cause adverse health effects. In the present study we have assessed the dustiness in terms of microbial components and particles of various biofuels by using a rotating drum as a dust generator. Microbial components from straw, wood chips, wood pellets and wood briquettes were quantified by several methods. Excellent correlations (r {>=} 0.85, P < 0.0001) were found: between lipopolysaccharide (LPS) (as determined by 3-hydroxy fatty acid analysis) and endotoxin (as determined by a Limulus test), cultivable bacteria, total number of bacteria and muramic acid; between endotoxin and cultivable bacteria, total number of bacteria and muramic acid; between total number of bacteria and muramic acid; between cultivable fungi and total number of fungi. Straw was dustier than the other biofuels in terms of actinomycetes, bacteria, muramic acid, endotoxin, LPS, particle mass and number of particles. One of the wood chips studied and the straws had comparatively high dustiness in terms of fungi, while both wood pellets and wood briquettes had comparatively low dustiness in terms of all microbial components. An initially high particle generation rate of straw and wood chips decreased over time whereas the particle generation rate of wood briquettes and wood pellets increased during a 5 min rotation period. Particles of non-microbial origin may be the determining factor for the health risk in handling briquettes and pellets. Straw dust contained significantly more microorganisms per particle than did wood chip dust, probably because bacteria were most abundant in straw dust. The concentrations of endotoxin and fungi were high in wood and straw dust; dust from one of the straws contained 3610 EU/mg and dust from one of the chips contained 7.3 x 10{sup 6} fungal spores/mg. An exposure to 3 mg of straw or wood chips dust/m{sup 3} (the Swedish and Danish OEL of unspecific inhaleable dust) could cause exposures to endotoxin and
Nath, G.; Vishwakarma, J. P.
2016-06-01
The propagation of a strong spherical shock wave in a dusty gas with or without self-gravitational effects is investigated in the case of isothermal and adiabatic flows. The dusty gas is assumed to be a mixture of small solid particles and perfect gas. The equilibrium flow conditions are assumed to be maintained, and the density of the mixture is assumed to be varying and obeying an exponential law. Non-similarity solutions are obtained and the effects of variations of the mass concentration of solid particles in the mixture and the ratio of the density of solid particles to the initial density of the gas, and the presence of self-gravitational field on the flow variables are investigated at given times. Our analysis reveals that after inclusion of gravitational field effects surprisingly the shock strength increases and remarkable differences are found in the distribution of flow variables. An increase in time also, increases the shock strength. Further, it is investigated that the consideration of isothermal flow increases the shock strength, and removes the singularity in the density distribution. Also, the presence of gravitational field increases the compressibility of the medium, due to which it is compressed and therefore the distance between the inner contact surface and the shock surface is reduced. The shock waves in self-gravitating dusty gas can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, star formation and shocks in stellar explosion, nuclear explosion, in industry, rupture of a pressurized vessel and explosion in the ionosphere. Other potential applications of this study include analysis of data from exploding wire experiments and cylindrically symmetric hypersonic flow problems associated with meteors or re-entry of vehicles etc. A comparison is made between the solutions in the cases of the gravitating and the non-gravitating media. The obtained solutions are applicable for
Cassini-plasma interactions in the Enceladus torus
Yaroshenko, V. V.; Miloch, W. J.; Morfill, G. E.
2012-04-01
This study reports the results of the first simulations of spacecraft-plasma interactions within the proposed Enceladus torus, a radially narrow toroidal region surrounding Saturn that contains a high density of water-group neutrals. Charge exchange collisions scatter these neutrals and replace a fraction of the co-rotating ions with a new and slower-moving ion population. The newly-created ions are moving near the local Keplerian speed, slower than the co-rotation speed, and are ''picked-up'' by Saturn's magnetic field. These water-group ions are detected throughout the Enceladus torus including regions far from Enceladus [1,2]. Three-dimensional particle-in-cell self-consistent code is applied to find the potential and plasma distributions around the spherical model of Cassini in a complicated plasma environment of the Enceladus torus. The modeling includes two types of water group ions (co-rotating, and non-thermalized pick-up ions), plasma flows, photoemission due to solar UV radiation, and flyby geometry. As input data the parameters derived from the Cassini plasma spectrometer measurements obtained in 2005 on Oct. 11, and 29, Nov. 27, and Dec. 24 [1] are employed. The numerical simulations show that the pick-up ions significantly modify the spatial structure of the plasma perturbations, arising in the vicinity of the orbiter in comparison to that obtained for only co-rotating ions [3]. The plasma species produce a specific strongly inhomogeneous configuration with a self-consistent charge separation between the different plasma components in the electric field of the orbiter. The highly energetic co-rotating water group ions are mainly responsible for the configuration of the plasma wake. The region extending up to a few electron Debye lengths downstream of the spacecraft reveals negative potentials that are a significant fraction of the thermal electron energy. Arising wake electric fields capture the cold, pick-up ions and lead to a strong enhancement of
Energy Technology Data Exchange (ETDEWEB)
Gerhardt, S.P., Menard, J.E., and the NSTX Research Team
2008-12-17
A detailed analysis of the plasma current quench in the National Spherical Torus Experiment [M.Ono, et al Nuclear Fusion 40, 557 (2000)] is presented. The fastest current quenches are fit better by a linear waveform than an exponential one. Area-normalized current quench times down to .4 msec/m2 have been observed, compared to the minimum of 1.7 msec/m2 recommendation based on conventional aspect ratio tokamaks; as noted in previous ITPA studies, the difference can be explained by the reduced self-inductance at low aspect ratio and high-elongation. The maximum instantaneous dIp/dt is often many times larger than the mean quench rate, and the plasma current before the disruption is often substantially less than the flat-top value. The poloidal field time-derivative during the disruption, which is directly responsible for driving eddy currents, has been recorded at various locations around the vessel. The Ip quench rate, plasma motion, and magnetic geometry all play important roles in determining the rate of poloidal field change.
Analysis of performance improvements for host and GPU interface of the APENet+ 3D Torus network
Ammendola A, R.; Biagioni, A.; Frezza, O.; Lo Cicero, F.; Lonardo, A.; Paolucci, P. S.; Rossetti, D.; Simula, F.; Tosoratto, L.; Vicini, P.
2014-06-01
APEnet+ is an INFN (Italian Institute for Nuclear Physics) project aiming to develop a custom 3-Dimensional torus interconnect network optimized for hybrid clusters CPU-GPU dedicated to High Performance scientific Computing. The APEnet+ interconnect fabric is built on a FPGA-based PCI-express board with 6 bi-directional off-board links showing 34 Gbps of raw bandwidth per direction, and leverages upon peer-to-peer capabilities of Fermi and Kepler-class NVIDIA GPUs to obtain real zero-copy, GPU-to-GPU low latency transfers. The minimization of APEnet+ transfer latency is achieved through the adoption of RDMA protocol implemented in FPGA with specialized hardware blocks tightly coupled with embedded microprocessor. This architecture provides a high performance low latency offload engine for both trasmit and receive side of data transactions: preliminary results are encouraging, showing 50% of bandwidth increase for large packet size transfers. In this paper we describe the APEnet+ architecture, detailing the hardware implementation and discuss the impact of such RDMA specialized hardware on host interface latency and bandwidth.
Cassini UVIS observations of the Io plasma torus. II. Radial variations
Steffl, Andrew J; Stewart, A Ian F; 10.1016/j.icarus.2004.04.016
2013-01-01
On January 14, 2001, shortly after the Cassini spacecraft's closest approach to Jupiter, the Ultraviolet Imaging Spectrometer (UVIS) made a radial scan through the midnight sector of Io plasma torus. The Io torus has not been previously observed at this local time. The UVIS data consist of 2-D spectrally dispersed images of the Io plasma torus in the wavelength range of 561{\\AA}-1912{\\AA}. We developed a spectral emissions model that incorporates the latest atomic physics data contained in the CHIANTI database in order to derive the composition of the torus plasma as a function of radial distance. Electron temperatures derived from the UVIS torus spectra are generally less than those observed during the Voyager era. We find the torus ion composition derived from the UVIS spectra to be significantly different from the composition during the Voyager era. Notably, the torus contains substantially less oxygen, with a total oxygen-to-sulfur ion ratio of 0.9. The average ion charge state has increased to 1.7. We de...
Vector-valued Jack polynomials and wavefunctions on the torus
Dunkl, Charles F.
2017-06-01
The Hamiltonian of the quantum Calogero-Sutherland model of N identical particles on the circle with 1/r 2 interactions has eigenfunctions consisting of Jack polynomials times the base state. By use of the generalized Jack polynomials taking values in modules of the symmetric group and the matrix solution of a system of linear differential equations one constructs novel eigenfunctions of the Hamiltonian. Like the usual wavefunctions each eigenfunction determines a symmetric probability density on the N-torus. The construction applies to any irreducible representation of the symmetric group. The methods depend on the theory of generalized Jack polynomials due to Griffeth, and the Yang-Baxter graph approach of Luque and the author.
Cornering Gapless Quantum States via Their Torus Entanglement
Witczak-Krempa, William; Hayward Sierens, Lauren E.; Melko, Roger G.
2017-02-01
The entanglement entropy (EE) has emerged as an important window into the structure of complex quantum states of matter. We analyze the universal part of the EE for gapless systems on tori in 2D and 3D, denoted by χ . Focusing on scale-invariant systems, we derive general nonperturbative properties for the shape dependence of χ and reveal surprising relations to the EE associated with corners in the entangling surface. We obtain closed-form expressions for χ in 2D and 3D within a model that arises in the study of conformal field theories (CFTs), and we use them to obtain Ansätze without fitting parameters for the 2D and 3D free boson CFTs. Our numerical lattice calculations show that the Ansätze are highly accurate. Finally, we discuss how the torus EE can act as a fingerprint of exotic states such as gapless quantum spin liquids, e.g., Kitaev's honeycomb model.
The Picard Group of a Noncommutative Algebraic Torus
Berest, Yuri; Tang, Xiang
2010-01-01
We compute the Picard group $ Pic(A_q) $ of the noncommutative algebraic 2-torus $A_q$, describe its action on the space $ R(A_q) $ of isomorphism classes of rk 1 projective modules and classify the algebras Morita equivalent to $ A_q $. Our computations are based on a quantum version of the Calogero-Moser correspondence relating projective $A_q$-modules to irreducible representations of the double affine Hecke algebras (DAHA) $ H_{t, q^{-1/2}}(S_n) $ at $ t = 1 $. We show that, under this correspondence, the action of $ Pic(A_q) $ on $ R(A_q) $ agrees with the action of $ SL_2(Z) $ on $ H_{t, q^{-1/2}}(S_n) $ constructed by I.Cherednik. We compare our results with smooth and analytic cases. In particular, when $ |q| \
I/O routing in a multidimensional torus network
Energy Technology Data Exchange (ETDEWEB)
Chen, Dong; Eisley, Noel A.; Heidelberger, Philip
2017-02-07
A method, system and computer program product are disclosed for routing data packet in a computing system comprising a multidimensional torus compute node network including a multitude of compute nodes, and an I/O node network including a plurality of I/O nodes. In one embodiment, the method comprises assigning to each of the data packets a destination address identifying one of the compute nodes; providing each of the data packets with a toio value; routing the data packets through the compute node network to the destination addresses of the data packets; and when each of the data packets reaches the destination address assigned to said each data packet, routing said each data packet to one of the I/O nodes if the toio value of said each data packet is a specified value. In one embodiment, each of the data packets is also provided with an ioreturn value used to route the data packets through the compute node network.
A negative mass theorem for the 2-Torus
Okikiolu, Kate
2007-01-01
For a closed surface M with metric g, the Robin mass m(p) at the point p is the value of the Green function G(p,q) at p=q after the logarithmic singularity has been removed. The Laplacian mass is the average value of the Robin mass, minus the value of the Robin mass for the round sphere of the same area. The Laplacian mass is a spectral invariant which is a natural analog of the ADM mass for asymptotically flat manifolds. We show that if M is a torus, then the minimum value of the Laplacian mass on the conformal class of g is negative. It is attained by a (smooth) metric for which one gets a sharp logarithmic Hardy-Littlewood-Sobolev inequality and Onofri-type inequality.
Measurement of Poloidal Velocity on the National Spherical Torus Experiment
Energy Technology Data Exchange (ETDEWEB)
Ronald E. Bell and Russell Feder
2010-06-04
A diagnostic suite has been developed to measure impurity poloidal flow using charge exchange recombination spectroscopy on the National Spherical Torus Experiment. Toroidal and poloidal viewing systems measure all quantities required to determine the radial electric field. Two sets of up/down symmetric poloidal views are used to measure both active emission in the plane of the neutral heating beams and background emission in a radial plane away from the neutral beams. Differential velocity measurements isolate the line-integrated poloidal velocity from apparent flows due to the energy-dependent chargeexchange cross section. Six f/1.8 spectrometers measure 276 spectra to obtain 75 active and 63 background channels every 10 ms. Local measurements from a similar midplane toroidal viewing system are mapped into two dimensions to allow the inversion of poloidal line-integrated measurements to obtain local poloidal velocity profiles. Radial resolution after inversion is 0.6-1.8 cm from the plasma edge to the center.
Physics Basis for a Spherical Torus Power Plant
Energy Technology Data Exchange (ETDEWEB)
C.E. Kessel; J. Menard; S.C. Jardin; T.K. Mau; et al
1999-11-01
The spherical torus, or low-aspect-ratio tokamak, is considered as the basis for a fusion power plant. A special class of wall-stabilized high-beta high-bootstrap fraction low-aspect-ratio tokamak equilibrium are analyzed with respect to MHD stability, bootstrap current and external current drive, poloidal field system requirements, power and particle exhaust and plasma operating regime. Overall systems optimization leads to a choice of aspect ratio A = 1:6, plasma elongation kappa = 3:4, and triangularity delta = 0:64. The design value for the plasma toroidal beta is 50%, corresponding to beta N = 7:4, which is 10% below the ideal stability limit. The bootstrap fraction of 99% greatly alleviates the current drive requirements, which are met by tangential neutral beam injection. The design is such that 45% of the thermal power is radiated in the plasma by Bremsstrahlung and trace Krypton, with Neon in the scrapeoff layer radiating the remainder.
Quantum entanglement in topological phases on a torus
Luo, Zhu-Xi; Hu, Yu-Ting; Wu, Yong-Shi
2016-08-01
In this paper, we study the effect of nontrivial spatial topology on quantum entanglement by examining the degenerate ground states of a topologically ordered system on a torus. Using the string-net (fixed-point) wave function, we propose a general formula of the reduced density matrix when the system is partitioned into two cylinders. The cylindrical topology of the subsystems makes a significant difference in regard to entanglement: a global quantum number for the many-body states comes into play, together with a decomposition matrix M which describes how topological charges of the ground states decompose into boundary degrees of freedom. We obtain a general formula for entanglement entropy and generalize the concept of minimally entangled states to minimally entangled sectors. Concrete examples are demonstrated with data from both finite groups and modular tensor categories (i.e., Fibonacci, Ising, etc.), supported by numerical verification.
Confined Aerosol Jet in Fiber Classification and Dustiness Measurement
Dubey, Prahit
The focus of this dissertation is the numerical analysis of confined aerosol jets used in fiber classification and dustiness measurement. Of relevance to the present work are two devices, namely, the Baron Fiber Classifier (BFC), and the Venturi Dustiness Tester (VDT). The BFC is a device used to length-separate fibers, important for toxicological research. The Flow Combination Section (FCS) of this device consists of an upstream region, where an aerosol of uncharged fibers is introduced in the form of an annular jet, in-between two sheath flows. Length-separation occurs by dielectrophoresis, downstream of the FCS in the Fiber Classification Section (FClS). In its standard operation, BFC processes only small quantities of fibers. In order to increase its throughput, higher aerosol flow rates must be considered. The goal of the present investigation is to understand the interaction of sheath and aerosol flows inside the FCS, and to identify possible limits to increasing aerosol flow rates using Computational Fluid Dynamics (CFD). Simulations involve solution of Navier-Stokes equations for axisymmetric and 3D models of the FCS for six different flow rates, and a pure aerodynamic treatment of the aerosol jet. The results show that the geometry of the FCS, and the two sheath flows, are successful in preventing the emergence of vortices in the FCS for aerosol-to-sheath flow inlet velocity ratios below ≈ 50. For larger aerosol-to-sheath flow inlet velocity ratios, two vortices are formed, one near the inner cylinder and one near the outer cylinder. The VDT is a novel device for measuring the dustiness of powders, relevant for dust management and controlling hazardous exposure. It uses just 10 mg of the test powder for its operation, during which the powder is aerosolized and turbulently dispersed (Re = 19,900) for 1.5s into a 5.7 liter chamber; the aerosol is then gently sampled (Re = 2050) for 240s through two filters located at the chamber top. Pump-driven suction at
Energy Technology Data Exchange (ETDEWEB)
Gerhardt, S. P.; Brennan, D. P.; Buttery, R.; La Haye, R. J.; Sabbagh, S.; Strait, E.; Bell, M.; Bell, R.; Fredrickson, E.; Gates, D.; LeBlanc, B.; Menard, J.; Stutman, D.; Tritz, K.; Yuh, H.
2009-02-24
The onset conditions for the m/n=2/1 neoclassical tearing mode (NTM) are studied in terms of neoclassical drive, triggering instabilities, and toroidal rotation or rotation shear, in the spherical torus NSTX [M. Ono, et al., Nuclear Fusion 40, 557 (2000)]. There are three typical onset conditions for these modes, given in order of increasing neoclassical drive required for mode onset: triggering by energetic particle modes, triggering by edge localized modes, and cases where the modes appear to grow without a trigger. In all cases, the required drive increases with toroidal rotation shear, implying a stabilizing effect from the shear.
Tuan, P H; Yu, Y T; Chiang, P Y; Liang, H C; Huang, K F; Chen, Y F
2012-02-01
We thoroughly analyze the level statistics and eigenfunctions in concentric as well as nonconcentric square torus billiards. We confirm the characteristics of quantum and classical correspondence and the existence of scarred and superscarred modes in concentric square torus billiards. Furthermore, we not only verify that the transition from regular to chaotic behaviors can be manifested in nonconcentric square torus billiards, but also develop an analytical distribution to excellently fit the numerical level statistics. Finally, we intriguingly observe that numerous eigenstates commonly exhibit the wave patterns to be an ensemble of classical diamond trajectories, as the effective wavelengths are considerably shorter than the size of internal hole.
Three-dimensional wake potential in a streaming dusty plasma
Indian Academy of Sciences (India)
M Salahuddin; M K Islam; A K Banerjee; M Salimullah; S K Ghosh
2003-09-01
The oscillatory wake potential for a slowly moving or static test dust particulate in a ﬁnite temperature, collisionless and unmagnetized dusty plasma with a continuous ﬂow of ions and dust particles has been studied. The collective resonant interaction of the moving test particle with the low-frequency and low-phase-velocity dust-acoustic mode is the origin of the periodic attractive force between the like polarity particulates along and perpendicular to the streaming ions and dust grains resulting into dust-Coulomb crystal formation. This wake potential can explain the three-dimensional dust-Coulomb crystal formation in the laboratory conditions.
Heat conduction in 2D strongly-coupled dusty plasmas
Hou, Lu-Jing
2008-01-01
We perform non-equilibrium simulations to study heat conduction in two-dimensional strongly coupled dusty plasmas. Temperature gradients are established by heating one part of the otherwise equilibrium system to a higher temperature. Heat conductivity is measured directly from the stationary temperature profile and heat flux. Particular attention is paid to the influence of damping effect on the heat conduction. It is found that the heat conductivity increases with the decrease of the damping rate, while its magnitude confirms previous experimental measurement.
Shear Flow instability in a strongly coupled dusty plasma
Banerjee, D; Chakrabarti, N
2013-01-01
Linear stability analysis of strongly coupled incompressible dusty plasma in presence of shear flow has been carried out using Generalized Hydrodynamical(GH) model. With the proper Galilean invariant GH model, a nonlocal eigenvalue analysis has been done using different velocity profiles. It is shown that the effect of elasticity enhances the growth rate of shear flow driven Kelvin- Helmholtz (KH) instability. The interplay between viscosity and elasticity not only enhances the growth rate but the spatial domain of the instability is also widened. The growth rate in various parameter space and the corresponding eigen functions are presented.
The Bohm criterion for a dusty plasma sheath
Indian Academy of Sciences (India)
B P Pandey; Anjan Dutta
2005-07-01
The formation of the sheath in a dusty plasma is investigated. The Bohm criterion is derived for two different cases: (a) when electrons are in thermodynamic equilibrium and dust grains provide the immobile, stationary background and (b) when both electrons and ions are in thermodynamic equilibrium and dust grains are moving. In the first case, Bohm criterion gets modified due to the fluctuation of the charge on the grain surface. In the second case, the collisional and Coulombic drag play important role in determining the Bohm criterion.
VELOCITY SHEAR INSTABILITY IN DUSTY PLASMAS OF COMET
Institute of Scientific and Technical Information of China (English)
Lu Li; Li Zhongyuan
2000-01-01
The velocity shear instability in a magnetized, three-component dusty plasma is investigated for both positively and negatively charged dust particles. The critical shears as a function of the relative charge of dust grains for both positively and negatively charged dust grains are in the same form. The instability excitation is easier in colder proton's environment for positively charged dust, and so also in colder electron's environment for negatively charged dust. For a certain flow pattern, the instability excites in different direction for different sign of charged dust grains. This conclusion may be helpful in interpreting the helical structures and streamer splitted phenomena in a cometary tail.
Jeans instability of an inhomogeneous streaming dusty plasma
Indian Academy of Sciences (India)
B P Pandey; B Van Der Holst; J Vranješ; S Poedts
2003-07-01
The dynamics of a self-gravitating unmagnetized, inhomogeneous, streaming dusty plasma is studied in the present work. The presence of the shear ﬂow causes the coupling between gravitational and electrostatic forces. In the absence of self-gravity, the ﬂuctuations in the plasma may grow at the expense of the density inhomogeneity and for certain wavelengths, such an unstable mode may dominate the usual streaming instability. However, in the presence of self-gravity, the plasma inhomogeneity causes an overlap between Jeans and streaming modes and collapse of the grain will continue at all wavelengths.
Parametric instabilities in magnetized bi-ion and dusty plasmas
Indian Academy of Sciences (India)
N F Cramer; M P Hertzberg; S V Vladimirov
2003-12-01
The excitation of low frequency modes of oscillations in a magnetized bi-ion or dusty plasma with parametric pumping of the magnetic ﬁeld is analysed. The equation of motion governing the perturbed plasma is derived and parametrically excited transverse modes propagating along the magnetic ﬁeld are found. With multiple ion species or charged dust present, a number of different circularly polarized modes can be excited. The stability of these modes is investigated as a function of the plasma parameters. The modulational instabilities of large amplitude normal modes, modiﬁed by the extra ion species or dust and propagating along the magnetic ﬁeld, are also investigated.
Sahai, R; Patel, N A; Contreras, C S; Morris, M
2006-01-01
We report high angular-resolution (~1") CO J=3--2 interferometric mapping, using the Submillimeter Array (SMA), of IRAS22036+5306 (I22036), a bipolar pre-planetary nebula (PPN) with knotty jets discovered in our HST SNAPshot survey of young PPNs. In addition, we have obtained supporting lower-resolution (~10") CO and 13CO J=1-0 observations with the Owens Valley Radio Observatory (OVRO) interferometer, as well as optical long-slit echelle spectra at the Palomar Observatory. The CO J=3-2 observations show the presence of a very fast (~220 km/s), highly collimated, massive (0.03 Msun) bipolar outflow with a very large scalar momentum (about 10^{39} g cm s^{-1}), and the characteristic spatio-kinematic structure of bow-shocks at the tips of this outflow. The Halpha line shows an absorption feature blue-shifted from the systemic velocity by ~100 km/s, which most likely arises in neutral interface material between the fast outflow and the dense walls of the bipolar lobes at low latitudes. The fast outflow in I2203...
Goad, M R; Ruff, A J
2012-01-01
(Abridged) We investigate the observational characteristics of BLR geometries in which the BLR clouds bridge the gap, both in distance and scale height, between the outer accretion disc and the hot dust, forming an effective surface of a "bowl". The gas dynamics are dominated by gravity, and we include the effects of transverse Doppler shift, gravitational redshift and scale-height dependent macro-turbulence. Our simple model reproduces many of the phenomena observed in broad emission-line variability studies, including (i) the absence of response in the core of the optical recombination lines on short timescales, (ii) the enhanced red-wing response on short timescales, (iii) differences between the measured delays for the HILs and LILs, and (iv) identifies turbulence as a means of producing Lorentzian profiles (esp. for LILs) in low inclination systems, and for suppressing significant continuum--emission-line delays between the line wings and line core (esp. in LILs). A key motivation of this work was to rev...
Influence of self-gravity on the runaway instability of black-hole-torus systems.
Montero, Pedro J; Font, José A; Shibata, Masaru
2010-05-14
Results from the first fully general relativistic numerical simulations in axisymmetry of a system formed by a black hole surrounded by a self-gravitating torus in equilibrium are presented, aiming to assess the influence of the torus self-gravity on the onset of the runaway instability. We consider several models with varying torus-to-black-hole mass ratio and angular momentum distribution orbiting in equilibrium around a nonrotating black hole. The tori are perturbed to induce the mass transfer towards the black hole. Our numerical simulations show that all models exhibit a persistent phase of axisymmetric oscillations around their equilibria for several dynamical time scales without the appearance of the runaway instability, indicating that the self-gravity of the torus does not play a critical role favoring the onset of the instability, at least during the first few dynamical time scales.
Cassini UVIS Observations of the Io Plasma Torus. IV. Modeling Temporal and Azimuthal Variability
Steffl, A J; Bagenal, F
2007-01-01
In this fourth paper in a series, we present the results of our efforts to model the remarkable temporal and azimuthal variability of the Io plasma torus during the Cassini encounter with Jupiter. The long-term (months) temporal variation in the average torus composition observed by the Cassini Ultraviolet Imaging Spectrograph (UVIS) can be modeled by supposing a factor of ~4 increase in the amount of material supplied to the extended neutral clouds that are the source of torus plasma, followed by a gradual decay to more "typical" values. On shorter timescales, the observed 10.07-hour torus periodicity and azimuthal variation in plasma composition, including its surprising modulation with System III longitude, is reproduced by our model using the superposition of two azimuthal variations of suprathermal electrons: a primary hot electron variation that slips 12.5 degrees/day relative to the Jovian magnetic field and a secondary variation that remains fixed in System III longitude.
Torus-invariant prime ideals in quantum matrices, totally nonnegative cells and symplectic leaves
Goodearl, K R; Lenagan, T H
2009-01-01
The algebra of quantum matrices of a given size supports a rational torus action by automorphisms. It follows from work of Letzter and the first named author that to understand the prime and primitive spectra of this algebra, the first step is to understand the prime ideals that are invariant under the torus action. In this paper, we prove that a family of quantum minors is the set of all quantum minors that belong to a given torus-invariant prime ideal of a quantum matrix algebra if and only if the corresponding family of minors defines a non-empty totally nonnegative cell in the space of totally nonnegative real matrices of the appropriate size. As a corollary, we obtain explicit generating sets of quantum minors for the torus-invariant prime ideals of quantum matrices in the case where the quantisation parameter $q$ is transcendental over $\\mathbb{Q}$.
The vertical thickness of Jupiter's Europa gas torus from charged particle measurements
Kollmann, P.; Paranicas, C.; Clark, G.; Roussos, E.; Lagg, A.; Krupp, N.
2016-09-01
Measurements and modeling suggest the presence of a neutral gas torus collocated with the orbit of Jupiter's moon Europa. Here we use data from the CMS instrument that is part of the Energetic Particles Detector (EPD) on board the Galileo spacecraft to characterize the distribution of 130 keV protons. Near the orbit of Europa this distribution has a minimum around 70° in equatorial pitch angle. We reproduce this with a model assuming that the protons are lost via charge exchange with a gas torus. Since the pitch angle characterizes whether the protons remain mostly in the dense center of the torus or continuously bounce through it, we can determine the latitudinal extent of the torus. We find that the full thickness where its density falls to 1/e of its maximum has to be ≲2RJ and is closer to ≈1RJ.
Real Baum-Connes assembly and T-duality for torus orientifolds
Rosenberg, Jonathan
2015-03-01
We show that the real Baum-Connes conjecture for abelian groups, possibly twisted by a cocycle, explains the isomorphisms of (twisted) KR-groups that underlie all T-dualities of torus orientifold string theories.
Collision and recombination driven instabilities in variable charged dusty plasmas
Indian Academy of Sciences (India)
S Bal; M Bose
2013-04-01
The dust-acoustic instability driven by recombination of electrons and ions on the surface of charged and variably-charged dust grains as well as by collisions in dusty plasmas with significant pressure of background neutrals have been theoretically investigated. The recombination driven instability is shown to be dominant in the long wavelength regime even in the presence of dust-neutral and ion-neutral collisions, while in the shorter wavelength regime, the dust-neutral collision is found to play a major role. In an earlier research work, the dust-neutral collision was neglected in comparison to the effect due to the recombination for estimating the dust-acoustic instability; later the other report shows that the recombination effect is negligible in the presence of dust-neutral collisions. In line of this present situation our investigation revealed that the recombination is more important than dust-neutral collisions in laboratory plasma and fusion plasma, while the dust-neutral collision frequency is dominant in the interstellar plasmas. The effects of ion and dust densities and ion streaming on the recombination and collision driven mode in parameter regimes relevant for many experimental studies on dusty plasmas have also been calculated.
The sub-arcsecond dusty environment of Eta Carinae
Chesneau, O; Herbst, T; Waters, L B F M; Hillier, D J; Leinert, C; De Koter, A; Pascucci, I; Jaffe, W; Köhler, R; Alvarez, C; Van Boekel, R; Brandner, W; Graser, U; Lagrange, A M; Lenzen, R; Morel, S; Schöller, M; Leinert, Ch
2005-01-01
The core of the nebula surrounding Eta Carinae has been observed with the VLT Adaptive Optics system NACO and with the interferometer VLTI/MIDI to constrain spatially and spectrally the warm dusty environment and the central object. In particular, narrow-band images at 3.74 and 4.05 micron reveal the butterfly shaped dusty environment close to the central star with unprecedented spatial resolution. A void whose radius corresponds to the expected sublimation radius has been discovered around the central source. Fringes have been obtained in the Mid-IR which reveal a correlated flux of about 100Jy situated 0.3" south-east of the photocenter of the nebula at 8.7 micron, which corresponds with the location of the star as seen in other wavelengths. This correlated flux is partly attributed to the central object, and these observations provide an upper limit for the SED of the central source from 2.2 to 13.5 micron. Moreover, we have been able to spectrally disperse the signal from the nebula itself at PA=318 degre...
Electrostatic solitary waves in dusty pair-ion plasmas
Energy Technology Data Exchange (ETDEWEB)
Misra, A. P. [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235, West Bengal (India); Adhikary, N. C. [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati-781035, Assam (India)
2013-10-15
The propagation of electrostatic waves in an unmagnetized collisionless pair-ion plasma with immobile positively charged dusts is studied for both large- and small-amplitude perturbations. Using a two-fluid model for pair-ions, it is shown that there appear two linear ion modes, namely the “fast” and “slow” waves in dusty pair-ion plasmas. The properties of these wave modes are studied with different mass (m) and temperature (T) ratios of negative to positive ions, as well as the effects of immobile charged dusts (δ). For large-amplitude waves, the pseudopotential approach is performed, whereas the standard reductive perturbation technique is used to study the small-amplitude Korteweg-de Vries (KdV) solitons. The profiles of the pseudopotential, the large amplitude solitons as well as the dynamical evolution of KdV solitons, are numerically studied with the system parameters as above. It is found that the pair-ion plasmas with positively charged dusts support the propagation of solitary waves (SWs) with only the negative potential. The results may be useful for the excitation of SWs in laboratory dusty pair-ion plasmas, electron-free industrial plasmas as well as for observation in space plasmas where electron density is negligibly small compared to that of negative ions.
Rapid disappearance of a warm, dusty circumstellar disk
Melis, Carl; Rhee, Joseph H; Song, Inseok; Murphy, Simon J; Bessell, Michael S
2012-01-01
Stars form with gaseous and dusty circumstellar envelopes, which rapidly settle into disks that eventually give rise to planetary systems. Understanding the process by which these disks evolve is paramount in developing an accurate theory of planet formation that can account for the variety of planetary systems discovered so far. The formation of Earth-like planets through collisional accumulation of rocky objects within a disk has mainly been explored in theoretical and computational work in which post-collision ejecta evolution is typically ignored, although recent work has considered the fate of such material. Here we report observations of a young, Sun-like star (TYC 8241 2652 1) where infrared flux from post-collisional ejecta has decreased drastically, by a factor of about 30, over a period of less than two years. The star seems to have gone from hosting substantial quantities of dusty ejecta, in a region analogous to where the rocky planets orbit in the Solar System, to retaining at most a meagre amoun...
Rapid disappearance of a warm, dusty circumstellar disk
Melis, Carl; Zuckerman, B.; Rhee, Joseph H.; Song, Inseok; Murphy, Simon J.; Bessell, Michael S.
2012-07-01
Stars form with gaseous and dusty circumstellar envelopes, which rapidly settle into disks that eventually give rise to planetary systems. Understanding the process by which these disks evolve is paramount in developing an accurate theory of planet formation that can account for the variety of planetary systems discovered so far. The formation of Earth-like planets through collisional accumulation of rocky objects within a disk has mainly been explored in theoretical and computational work in which post-collision ejecta evolution typically is ignored, although recent work has considered the fate of such material. Here we report observations of a young, Sun-like star (TYC 8241 2652 1) where infrared flux from post-collisional ejecta has decreased drastically, by a factor of about 30, over a period of less than two years. The star seems to have gone from hosting substantial quantities of dusty ejecta, in a region analogous to where the rocky planets orbit in the Solar System, to retaining at most a meagre amount of cooler dust. Such a phase of rapid ejecta evolution has not been previously predicted or observed, and no currently available physical model satisfactorily explains the observations.
Flowing dusty plasma experiments: generation of flow and measurement techniques
Jaiswal, S.; Bandyopadhyay, P.; Sen, A.
2016-12-01
A variety of experimental techniques for the generation of subsonic/supersonic dust fluid flows and means of measuring such flow velocities are presented. The experiments have been carried out in a \\Pi -shaped dusty plasma experimental device with micron size kaolin/melamine formaldehyde particles embedded in a background of argon plasma created by a direct current glow discharge. A stationary dust cloud is formed over the cathode region by precisely balancing the pumping speed and gas flow rate. A flow of dust particles/fluid is generated by additional gas injection from a single or dual locations or by altering the dust confining potential. The flow velocity is then estimated by three different techniques, namely, by super particle identification code, particle image velocimetry analysis and the excitation of dust acoustic waves. The results obtained from these three different techniques along with their merits and demerits are discussed. An estimation of the neutral drag force responsible for the generation as well as the attenuation of the dust fluid flow is made. These techniques can be usefully employed in laboratory devices to investigate linear and non-linear collective excitations in a flowing dusty plasma.
Dusty Star-Forming Galaxies at High Redshift
Casey, Caitlin M; Cooray, Asantha
2014-01-01
Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 10$^{13}$ L$_{\\odot}$ with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrare...
Optical diagnostics of dusty plasmas during nanoparticle growth
Mikikian, M.; Labidi, S.; von Wahl, E.; Lagrange, J. F.; Lecas, T.; Massereau-Guilbaud, V.; Géraud-Grenier, I.; Kovacevic, E.; Berndt, J.; Kersten, H.; Gibert, T.
2017-01-01
Carbon-based thin films deposited on surfaces exposed to a typical capacitively-coupled RF plasma are sources of molecular precursors at the origin of nanoparticle growth. This growth leads to drastic changes of the plasma characteristics. Thus, a precise understanding of the dusty plasma structure and dynamics is required to control the plasma evolution and the nanoparticle growth. Optical diagnostics can reveal some particular features occurring in these kinds of plasmas. High-speed imaging of the plasma glow shows that instabilities induced by nanoparticle growth can be constituted of small brighter plasma regions (plasmoids) that rotate around the electrodes. A single bigger region of enhanced emission is also of particular interest: the void, a main central dust-free region, has very distinct plasma properties than the surrounding dusty region. This particularity is emphasized using optical emission spectroscopy with spatiotemporal resolution. Emission profiles are obtained for the buffer gas and the carbonaceous molecules giving insights on the changes of the electron energy distribution function during dust particle growth. Dense clouds of nanoparticles are shown to be easily formed from two different thin films, one constituted of polymer and the other one created by the plasma decomposition of ethanol.
Nonlinear electrostatic waves in inhomogeneous dense dusty magnetoplasmas
Energy Technology Data Exchange (ETDEWEB)
Mahmood, S., E-mail: shahzad_mahmoodpk@yahoo.co [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Haque, Q. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)
2010-01-25
The nonlinear electrostatic drift waves are studied using quantum hydrodynamic model in dusty quantum magnetoplasmas. The dissipative effects due to collisions between ions and dust particles have also been taken into account. The Korteweg-de Vries Burgers (KdVB) like equation is derived and analytical solution is obtained using tanh method. The limiting cases of KdV type solitary waves, Burger type monotonic shock waves and oscillatory shock solutions are also presented. It is found that both hump and dip type solitary structures are possible in quantum dusty plasmas. However, amplitude and width of the nonlinear structure depend on the dust charge polarity and its concentration in electron-ion quantum plasmas. The monotonic shock like structure is independent of the quantum parameter. It is found that shock strength is increased in the presence of positively charged particles in comparison with negatively charged dust particles. The oscillatory shock structures are also obtained and it is found that change in dust charge polarity only shifts the phase of the oscillatory shock in plasmas. The numerical results are also presented for illustration.
10D massive type IIA supergravities as the uplift of parabolic M2-brane torus bundles
Energy Technology Data Exchange (ETDEWEB)
Garcia del Moral, Maria Pilar [Universidad de Antofagasta (Chile). Dept. de Fisica; Restuccia, Alvaro [Universidad de Antofagasta (Chile). Dept. de Fisica; Universidad Simon Bolivar, Caracas (Venezuela, Bolivarian Republic of). Dept. de Fisica
2016-04-15
We remark that the two 10D massive deformations of the N = 2 maximal type IIA supergravity (Romans and HLW supergravity) are associated to the low energy limit of the uplift to 10D of M2-brane torus bundles with parabolic monodromy linearly and non-linearly realized respectively. Romans supergravity corresponds to M2-brane compactified on a twice-punctured torus bundle. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
SDN Data Center Performance Evaluation of Torus and Hypercube Interconnecting Schemes
DEFF Research Database (Denmark)
Andrus, Bogdan-Mihai; Vegas Olmos, Juan José; Mehmeri, Victor;
2015-01-01
— By measuring throughput, delay, loss-rate and jitter, we present how SDN framework yields a 45% performance increase in highly interconnected topologies like torus and hypercube compared to current Layer2 switching technologies, applied to data center architectures......— By measuring throughput, delay, loss-rate and jitter, we present how SDN framework yields a 45% performance increase in highly interconnected topologies like torus and hypercube compared to current Layer2 switching technologies, applied to data center architectures...
Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field
Das, Praloy; Pramanik, Souvik; Ghosh, Subir
2016-11-01
Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac's Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torus knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein-Brillouin-Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr-Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.
The massive expanding molecular torus in the planetary nebula NGC 6302
Peretto, N; Zijlstra, A A; Patel, N A
2007-01-01
We measure the mass and kinematics of the massive molecular torus in the planetary nebula NGC 6302. The nebula is the proto-typical butterfly nebula. The origin of the wing-like morphology is disputed: determining the mass-loss history of the confining torus is an important step in understanding the formation of this structure. We performed submillimeter observations with JCMT and the SMA interferometer. The continuum emission as well as the J=2-1 and 3-2 transitions of 12CO and 13CO are analysed at arcsecond resolution. The CO emission indicates a mass of the torus of ~ 2Msun +/- 1Msun. The 12CO and 13CO emission matches the dark lane seen in absorption in the Halpha image of the object. The CO torus is expanding with a velocity of ~ 8 km/s, centred at Vlsr=-31.5 km/s. The size and expansion velocity of the torus indicates that the torus was ejected from ~ 7500 yr to 2900 yr ago, with a mass-loss rate of 5x10^{-4}Msun/yr. We also see a ballistic component in the CO images with a velocity gradient of 140 km/s...
Surface ozone-aerosol behaviour and atmospheric boundary layer structure in Saharan dusty scenario
Adame, Jose; Córdoba-Jabonero, Carmen; Sorrribas, Mar; Gil-Ojeda, Manuel; Toledo, Daniel; Yela, Margarita
2016-04-01
A research campaign was performed for the AMISOC (Atmospheric Minor Species relevant to the Ozone Chemistry) project at El Arenosillo observatory (southwest Spain) in May-June 2012. The campaign focused on the impact of Saharan dust intrusions at the Atmospheric Boundary Layer (ABL) and ozone-aerosol interactions. In-situ and remote-sensing techniques for gases and aerosols were used moreover to modelling analyses. Meteorology features, ABL structures and evolution, aerosol profiling distributions and aerosol-ozone interactions on the surface were analysed. Two four-day periods were selected according to non-dusty (clean conditions) and dusty (Saharan dust) situations. In both scenarios, sea-land breezes developed in the lower atmosphere, but differences were found in the upper levels. Results show that surface temperatures were greater than 3°C and humidity values were lower during dusty conditions than non-dusty conditions. Thermal structures on the surface layer (estimated using an instrument on a 100 m tower) show differences, mainly during nocturnal periods with less intense inversions under dusty conditions. The mixing layer during dusty days was 400-800 m thick, less than observed on non-dusty days. Dust also disturbed the typical daily ABL evolution. Stable conditions were observed during the early evening during intrusions. Aerosol extinction on dusty days was 2-3 times higher, and the dust was confined between 1500 and 5500 m. Back trajectory analyses confirmed that the dust had an African origin. On the surface, the particle concentration was approximately 3.5 times higher during dusty events, but the local ozone did not exhibit any change. The arrival of Saharan dust in the upper levels impacted the meteorological surface, inhibited the daily evolution of the ABL and caused an increase in aerosol loading on the surface and at higher altitudes; however, no dust influence was observed on surface ozone.
Design of the new magnetic sensors for Joint European Torus
Coccorese, V.; Albanese, R.; Altmann, H.; Cramp, S.; Edlington, T.; Fullard, K.; Gerasimov, S.; Huntley, S.; Lam, N.; Loving, A.; Riccardo, V.; Sartori, F.; Marren, C.; McCarron, E.; Sowden, C.; Tidmarsh, J.; Basso, F.; Cenedese, A.; Chitarin, G.; DegliAgostini, F.; Grando, L.; Marcuzzi, D.; Peruzzo, S.; Pomaro, N.; Solano, E. R.
2004-10-01
A new magnetic diagnostics system has been designed for the 2005 Joint European Torus (JET) experimental campaigns onward. The new system, which adds to the existing sensors, aims to improve the JET safety, reliability, and performance, with respect to: (i) equilibrium reconstruction; (ii) plasma shape control; (iii) coil failures; (iv) VDEs; (v) iron modeling; and (vi) magnetohydrodynamics poloidal mode analysis. The system consists of in-vessel and ex-vessel sensors. The former are a set of 38 coil pairs (normal and tangential), located as near as possible to the plasma. Coils are generally grouped in rails, in order to ease remote handling in-vessel installation. The system includes: (i) two outer poloidal limiter arrays (2×7 coil pairs); (ii) two divertor region arrays (2×7 coil pairs); and (iii) two top coil arrays (2×5 coil pairs). Ex-vessel sensors, including discrete coils, Hall probes, and flux loops (26 in total) will be installed on the iron limbs, in order to provide experimental data for the treatment of iron in equilibrium codes. The design is accompanied by a software analysis, aiming to predict the expected improvement.
Ideal magnetohydrodynamic equilibrium in a non-symmetric topological torus
Energy Technology Data Exchange (ETDEWEB)
Weitzner, Harold [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)
2014-02-15
An alternative representation of an ideal magnetohydrodynamic equilibrium is developed. The representation is a variation of one given by A. Salat, Phys. Plasmas 2, 1652 (1995). The system of equations is used to study the possibility of non-symmetric equilibria in a topological torus, here an approximate rectangular parallelopiped, with periodicity in two of the three rectangular coordinates. An expansion is carried out in the deviation of pressure surfaces from planes. Resonances are manifest in the process. Nonetheless, provided the magnetic shear is small, it is shown that it is possible to select the magnetic fields and flux surfaces in such a manner that no singularities appear on resonant surfaces. One boundary surface of the parallelopiped is not arbitrary but is dependent on the equilibrium in question. A comparison of the solution sets of axisymmetric and non-axisymmetric equilibria suggests that the latter have a wider class of possible boundary shapes but more restrictive rotational transform profiles. No proof of convergence of the series is given.
On the dynamics of tilted black hole-torus systems
Mewes, Vassilios; Font, José A; Montero, Pedro J; Stergioulas, Nikolaos
2016-01-01
We present results from three-dimensional, numerical relativity simulations of a tilted black hole-thick accretion disc system. The simulations are analysed using tracer particles in the disc which are advected with the flow. Such tracers, which we employ in these new simulations for the first time, provide a powerful means to analyse in detail the complex dynamics of tilted black hole-torus systems. We show how its use helps to gain insight in the overall dynamics of the system, discussing the origin of the observed black hole precession and the development of a global non-axisymmetric $m=1$ mode in the disc. Our three-dimensional simulations show the presence of quasi-periodic oscillations (QPOs) in the instantaneous accretion rate, with frequencies in a range compatible with those observed in low mass X-ray binaries with either a black hole or a neutron star component. The frequency ratio of the dominant low frequency peak and the first overtone is $o_1/f \\sim 1.9$, a frequency ratio not attainable when mo...
Strike Point Control for the National Spherical Torus Experiment (NSTX)
Energy Technology Data Exchange (ETDEWEB)
Kolemen, E.; Gates, D. A.; Rowley, C. W.; Kasdin, N. J.; Kallman, J.; Gerhardt, S.; Soukhanovskii, V.; Mueller, D.
2010-07-09
This paper presents the first control algorithm for the inner and outer strike point position for a Spherical Torus (ST) fusion experiment and the performance analysis of the controller. A liquid lithium divertor (LLD) will be installed on NSTX which is believed to provide better pumping than lithium coatings on carbon PFCs. The shape of the plasma dictates the pumping rate of the lithium by channeling the plasma to LLD, where strike point location is the most important shape parameter. Simulations show that the density reduction depends on the proximity of strike point to LLD. Experiments were performed to study the dynamics of the strike point, design a new controller to change the location of the strike point to desired location and stabilize it. The most effective PF coils in changing inner and outer strike points were identified using equilibrium code. The PF coil inputs were changed in a step fashion between various set points and the step response of the strike point position was obtained. From the analysis of the step responses, PID controllers for the strike points were obtained and the controller was tuned experimentally for better performance. The strike controller was extended to include the outer-strike point on the inner plate to accommodate the desired low outer-strike points for the experiment with the aim of achieving "snowflake" divertor configuration in NSTX.
Current drive experiments in the Helicity Injected Torus - II
Hamp, W. T.; Redd, A. J.; Jarboe, T. R.; Nelson, B. A.; O'Neill, R. G.; Raman, R.; Sieck, P. E.; Smith, R. J.; Mueller, D.
2006-10-01
The HIT-II spherical torus (ST) device has demonstrated four toroidal plasma current drive configurations to form and sustain a tokamak: 1) inductive (ohmic) current drive, 2) coaxial helicity injection (CHI) current drive, 3) CHI initiated plasmas with ohmic sustainment (CHI+OH), and 4) ohmically initiated plasmas with CHI edge current drive (OH+ECD). CHI discharges with a sufficiently high ratio of injector current to toroidal field current form a closed flux core, and amplify the injector poloidal flux through magnetic reconnection. CHI+OH plasmas are more robust than unassisted ohmic discharges, with a wider operating space and more efficient use of the transformer Volt-seconds. Finally, edge CHI can enhance the plasma current of an ohmic discharge without significantly degrading the quality of the discharge. Results will be presented for each HIT-II operating regime, including empirical performance scalings, applicable parametric operating spaces, and requirements to produce these discharges. Thomson scattering measurements and EFIT simulations are used to evaluate confinement in several representative plasmas. Finally, we outline extensions to the HIT-II CHI studies that could be performed with NSTX, SUNIST, or other ST devices.
The formation and evolution of high-redshift dusty galaxies
Ma, Jingzhe; Gonzalez, Anthony H.; Ge, Jian; Vieira, Joaquin D.; Prochaska, Jason X.; Spilker, Justin; Strandet, Maria; Ashby, Matthew; Noterdaeme, Pasquier; Lundgren, Britt; Zhao, Yinan; Ji, Tuo; Zhang, Shaohua; Caucal, Paul; SPT SMG Collaboration
2017-01-01
Star formation and chemical evolution are among the biggest questions in galaxy formation and evolution. High-redshift dusty galaxies are the best sites to investigate mass assembly and growth, star formation rates, star formation history, chemical enrichment, and physical conditions. My thesis is based on two populations of high-redshift dusty galaxies, submillimeter galaxies (SMGs) and quasar 2175 Å dust absorbers, which are selected by dust emission and dust absorption, respectively.For the SMG sample, I have worked on the gravitationally lensed dusty, star-forming galaxies (DSFGs) at 2.8 thesis is focused on the stellar masses and star formation rates of these objects by means of multi-wavelength spectral energy distribution (SED) modelling. The data include HST/WFC3, Spitzer/IRAC, Herschel/PACS, Herschel/SPIRE, APEX/Laboca and SPT. Compared to the star-forming main sequence (MS), these DSFGs have specific SFRs that lie above the MS, suggesting that we are witnessing ongoing strong starburst events that may be driven by major mergers. SPT0346-52 at z = 5.7, the most extraordinary source in the SPT survey for which we obtained Chandra X-ray and ATCA radio data, was confirmed to have the highest star formation surface density of any known galaxy at high-z.The other half of my thesis is focused on a new population of quasar absorption line systems, 2175 Å dust absorbers, which are excellent probes of gas and dust properties, chemical evolution and physical conditions in the absorbing galaxies. This sample was selected from the SDSS and BOSS surveys and followed up with the Echelle Spectrographs and Imager on the Keck-II telescope, the Red & Blue Channel Spectrograph on the Multiple Mirror Telescope, and the Ultraviolet and Visible Echelle Spectrograph onboard the Very Large Telescope. We found a correlation between the presence of the 2175 Å bump and other ingredients including high metallicity, high depletion level, overall low ionization state of gas, neutral
Electrostatic Waves in Dense Dusty Plasmas with High Fugacity
Rao, N. N.
Propagation of electrostatic dust modes has been reviewed in the light of the concept of dust fugacity defined by f≡4πnd0λD2R, where nd0 and R are the dust number density and the grain size (radius) while the plasma Debye length (λD) is given through λD-2=λDe-2+λDi-2. Dusty plasmas are defined to be tenuous, dilute or dense when f≪1, ˜1, or ≫1, respectively. Attention is focused on “Dust-Acoustic Waves” (DAWs) and “Dust-Coulomb Waves” (DCWs) which exist in the tenuous (f≪1) and the dense (f≫1) regimes, respectively. A simple physical picture of the DCWs has been proposed in terms of an effective pressure called “Coulomb Pressure defined by PC≡nd0qd02/R, where qd0 is the grain charge. In the lowest order, the DCW phase speed is given by ω/k=PC/ρdδ, where ρd≡nd0md is the dust mass density and δ≡ω2/ω1 is the ratio of charging frequencies. Thus, DCWs which are driven by the Coulomb pressure can be considered as the electrostatic analogue of hydromagnetic (Alfvén or magnetoacoustic) modes which are driven by magnetic field pressure. In the dilute regime, the two waves loose their identities and merge into a single mode, which may be called “Dust Charge-Density Wave” (DCDW). When the grains are closest, DCW dispersion relation is identical with that of “Dust-Lattice Waves” (DLWs). Dense dusty plasmas are governed by a new scale-length defined by λR≡1/4πnd0Rδ, which characterizes the effective shielding length due to grain collective interactions. The scale-length λR plays a fundamental role in dense dusty plasmas, which is very similar to that of the Debye length λD in the tenuous regime. The two scale-lengths are related to the fugacity through fδ≡λD2/λR2. The frequency spectrum as well as the damping rates for various dust modes have been analytically obtained, and compared with the numerical solutions of the kinetic (Vlasov) dispersion relation.
Flow of a Dusty Gas Between Two Parallel Plates One Stationary and Other Oscillating
Directory of Open Access Journals (Sweden)
P. Mitra
1981-07-01
Full Text Available The solution for the flow of an incompressible viscous dusty gas, induced by two infinitely extended parallel plates when the lower plate is at rest and the upper plate begins to oscillate harmonically in its own plane, is obtained, It is found that (i with the increase in the mass concentration both the velocities of the dusty gas and the particle decreases, (ii the velocity of the dusty gas increases and that of the particle decreases with the increase in neta.
Three-Dimensional Dust-Acoustic Waves in a Collisional Dusty Plasma with Opposite Polarity Particles
Institute of Scientific and Technical Information of China (English)
LIN Mai-Mai; DUAN Wen-Shan
2005-01-01
The dispersion relation is derived for three-dimensional dust-acoustic waves in a current-driven dusty plasmas with both positively and negatively charged dust particles. The dependencies of the frequency and the growth rate on the wave number K, the intensity of magnetic field B, and the inclination angle θ have been numerically shown in this paper. The growth rate is negative for the laboratory dusty plasma, but it is positive for the cosmic dusty plasma.It is found that when the inclination angle θ = π/2, there is no instability. The effect of the electrostatic field E0 has also been studied in this paper.
Fortov, Vladimir
Dusty, or complex plasmas are composed of a weakly ionized gas and charged microparticles. Dust and dusty plasmas are ubiquitous in space -- they are present in planetary rings, cometary tails, interplanetary and interstellar clouds, the mesosphere, thunderclouds, they are found in the vicinity of artificial satellites and space stations, etc. Dusty plasmas formed by micronsize particles are actively investigated in many laboratories. This research has many interesting applications like nanomaterial synthesis, nanoparticle handling or particle waste removal just to mention a few. But, the most interesting application of dusty plasmas is the use as model systems for fundamental physics. It allows investigation on the most fundamental -- the kinetic level and provides insights into physics of solids and liquids with a precision not achievable in natural systems. Experiments performed on Earth are always altered or even hindered by gravity. Microgravity conditions are necessary to make investigations of large homogeneous 3-dimensional dusty plasma systems. Here we present the survey of results of the dusty plasma physics investigations under microgravity conditions with the help of experimental installations ``Plasma Crystal-1'' (PK-1) and ``PK-2'' used on the Orbital Station ``Mir'', and the unique experimental installations ``PK-3'' and ``PK-3 Plus'' used on the International Space Station. The use of these installations has given a possibility to obtain new knowledge on the dusty plasma properties. The phase transition from the isotropic liquid dusty plasma system to the so-called electrorheological plasma has been performed. The transition is the isotropic one and is fully reversible. The other interesting phenomenon is an interpenetration of two clouds of microparticles of different sizes. When a velocity of the penetrating particles is rather high the lane formation has been observed. This phenomenon is the non-equilibrium transition, depends upon peculiarities
Jain, Shweta; Sharma, Prerana; Chhajlani, R. K.
2017-05-01
The self-gravitational Jeans instability has been studied in dusty plasma containing significant background of neutral pressure and recombination of ions and electrons on the dust surface. The full dynamics of charged dust grains, ions and neutral species are employed considering the electrons as Maxwellian. We have derived the general dispersion relation for collisional dusty plasma with ionization, recombination and polarization force. The general dispersion relation describes the effects of considered parameters which are solved in different dusty plasma situations. Further, the dispersion relation is solved numerically. The present work is applicable to understand the structure formation of interstellar molecular clouds in astrophysical plasma.
SNS potential with exchange field in quantum dusty plasmas
Zeba, I.; Batool, Maryam; Khan, Arroj A.; Jamil, M.; Rozina, Ch
2017-02-01
The shielding potential of a static test charge is studied in quantum dusty plasmas. The plasma system consisting upon electrons, ions and negatively static charged dust species, is embedded in an ambient magnetic field. The modified equation of dispersion is derived using quantum hydrodynamic model (QHD) for magnetized plasmas. The quantum effects are inculcated through Fermi degenerate pressure, tunneling effect and exchange-correlation effects. The study of shielding is important to know the existence of the silence zones in space and astrophysical objects as well as crystal formation. The graphical description of the normalized potential depict the significance of the exchange and correlation effects arising through spin and other variables on the shielding potential.
Formation and dissociation of dust molecules in dusty plasma
Yan, Jia; Feng, Fan; Liu, Fucheng; Dong, Lifang; He, Yafeng
2016-09-01
Dust molecules are observed in a dusty plasma experiment. By using measurements with high spatial resolution, the formation and dissociation of the dust molecules are studied. The ion cloud in the wake of an upper dust grain attracts the lower dust grain nearby. When the interparticle distance between the upper dust grain and the lower one is less than a critical value, the two dust grains would form a dust molecule. The upper dust grain always leads the lower one as they travel. When the interparticle distance between them is larger than the critical value, the dust molecule would dissociate. Project supported by the National Natural Science Foundation of China (Grant Nos. 11205044 and 11405042), the Natural Science Foundation of Hebei Province, China (Grant Nos. A2011201006 and A2012201015), the Research Foundation of Education Bureau of Hebei Province, China (Grant No. Y2012009), the Program for Young Principal Investigators of Hebei Province, China, and the Midwest Universities Comprehensive Strength Promotion Project, China.
Wave spectra of 2D dusty plasma solids and liquids
Hou, Lu-Jing; Piel, Alexander; Murillo, Michael S
2009-01-01
Brownian dynamics simulations were carried out to study wave spectra of two-dimensional dusty plasma liquids and solids for a wide range of wavelengths. The existence of a longitudinal dust thermal mode was confirmed in simulations, and a cutoff wavenumber in the transverse mode was measured. Dispersion relations, resulting from simulations, were compared with those from analytical theories, such as the random-phase approximation (RPA), quasi-localized charged approximation (QLCA), and harmonic approximation (HA). An overall good agreement between the QLCA and simulations was found for wide ranges of states and wavelengths after taking into account the direct thermal effect in the QLCA, while for the RPA and HA good agreement with simulations were found in the high and low temperature limits, respectively.
The acoustic instabilities in magnetized collisional dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Pandey, B. P., E-mail: birendra.pandey@mq.edu.au [Department of Physics and Astrophysics, Macquarie University, Sydney, NSW 2109 (Australia); Vladimirov, S. V., E-mail: s.vladimirov@physics.usyd.edu.au [Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 (Russian Federation); Dwivedi, C. B., E-mail: jagatpurdwivedi@gmail.com [Ved–Vijnanam Pravartanam Samitihi, Pratapgarh (Awadh), Jagatpur, Bharat (India)
2014-09-15
The present work investigates the wave propagation in collisional dusty plasmas in the presence of electric and magnetic field. It is shown that the dust ion-acoustic waves may become unstable to the reactive instability whereas dust-acoustic waves may suffer from both reactive and dissipative instabilities. If the wave phase speed is smaller than the plasma drift speed, the instability is of reactive type whereas in the opposite case, the instability becomes dissipative in nature. Plasma in the vicinity of dust may also become unstable to reactive instability with the instability sensitive to the dust material: dielectric dust may considerably quench this instability. This has implications for the dust charging and the use of dust as a probe in the plasma sheath.
Mobility in a strongly coupled dusty plasma with gas
Liu, Bin; Goree, J.
2014-04-01
The mobility of a charged projectile in a strongly coupled dusty plasma is simulated. A net force F, opposed by a combination of collisional scattering and gas friction, causes projectiles to drift at a mobility-limited velocity up. The mobility μp=up/F of the projectile's motion is obtained. Two regimes depending on F are identified. In the high-force regime, μp∝F0.23, and the scattering cross section σs diminishes as up-6/5. Results for σs are compared with those for a weakly coupled plasma and for two-body collisions in a Yukawa potential. The simulation parameters are based on microgravity plasma experiments.
Mobility in a strongly coupled dusty plasma with gas
Liu, Bin
2014-01-01
The mobility of a charged projectile in a strongly coupled dusty plasma is simulated. A net force $F$, opposed by a combination of collisional scattering and gas friction, causes projectiles to drift at a mobility-limited velocity $u_p$. The mobility $\\mu_p=u_p/F$ of the projectile's motion is obtained. Two regimes depending on $F$ are identified. In the high force regime, $\\mu_p \\propto F^{0.23}$, and the scattering cross section $\\sigma_s$ diminishes as $u_p^{-6/5}$. Results for $\\sigma_s$ are compared with those for a weakly coupled plasma and for two-body collisions in a Yukawa potential. The simulation parameters are based on microgravity plasma experiments.
Hα Kinematics of High-z Dusty Star Forming Galaxies
Drew, Patrick; Casey, Caitlin; Hung, Chao-Ling; Cooray, Asantha R.; Sanders, David B.; Fu, Hai
2017-01-01
Dusty Star Forming Galaxies (DSFGs) have the highest star formation rates in the Universe, but compared with other star forming galaxies at z > ~1 they are difficult to characterize, physically. Their low number density and extreme dust obscuration has led to very few kinematic studies of DSFGs at optical wavelengths. We present a rest-frame optical kinematic analysis of 5 DSFGs at z ~1.5 using long slit spectroscopy obtained with MOSFIRE at Keck Observatory. From our high signal-to-noise spectra we simultaneously fit Hα, [NII] λ6548, and [NII] λ6583 along each slit to generate position-velocity diagrams. We infer the kinematic disturbances and derive dynamical masses in order to compare with other derived quantities such as fractional obscuration, stellar and gas fractions, and dust characteristics.
Dispersion relations for circular single and double dusty plasma chains
Tkachenko, D V; Misko, V R
2011-01-01
We derive dispersion relations for a system of identical particles confined in a two-dimensional annular harmonic well and which interact through a Yukawa potential, e.g., a dusty plasma ring. When the particles are in a single chain (i.e., a one-dimensional ring) we find a longitudinal acoustic mode and a transverse optical mode which show approximate agreement with the dispersion relation for a straight configuration for large radii of the ring. When the radius decreases, the dispersion relations modify: there appears an anticrossing of the modes near the crossing point resulting in a frequency gap between the lower and upper branches of the modified dispersion relations. For the double chain (i.e., a two-dimensional zigzag configuration) the dispersion relation has four branches: longitudinal acoustic and optical and transverse acoustic and optical.
Nonextensive dust acoustic waves in a charge varying dusty plasma
Bacha, Mustapha; Tribeche, Mouloud
2012-01-01
Our recent analysis on nonlinear nonextensive dust-acoustic waves (DA) [Amour and Tribeche in Phys. Plasmas 17:063702, 2010] is extended to include self-consistent nonadiabatic grain charge fluctuation. The appropriate nonextensive electron charging current is rederived based on the orbit-limited motion theory. Our results reveal that the amplitude, strength and nature of the nonlinear DA waves (solitons and shocks) are extremely sensitive to the degree of ion nonextensivity. Stronger is the electron correlation, more important is the charge variation induced nonlinear wave damping. The anomalous dissipation effects may prevail over that dispersion as the electrons evolve far away from their Maxwellian equilibrium. Our investigation may be of wide relevance to astronomers and space scientists working on interstellar dusty plasmas where nonthermal distributions are turning out to be a very common and characteristic feature.
Macroparticle Movement Velocity in Dusty Structures of Various Compositions
Khakhaev, A D; Podryadchikov, S F
2012-01-01
The results of experimental investigations of the movement velocity of a macroparticle in the dusty structures of various physicalchemical compositions formed in a stratified column of a dc glow discharge, are presented. The macroparticle substances are alumina (r = 10 - 35 microns), polydisperse Zn (r = 1 - 20 microns) and Zn0 (r = 20 - 35 microns). Plasma-forming gases are inert gases (Ne, Ar). The inverse relation between the velocity and the gas pressure (in the range 40-400 Pa) is found and, for the same material of macroparticles in different gas plasmas, is confirmed by theory and does not contradict observations. But, to explain a difference of quantitative data for macroparticles made from different materials in Ar plasma, the additional research is required.
Dippers and Dusty Disks Edges: A Unified Model
Bodman, Eva H L; Ansdell, Megan; Hippke, Michael; Boyajian, Tabetha S; Mamajek, Eric E; Blackman, Eric G; Rizzuto, Aaron; Kastner, Joel H
2016-01-01
A search for dips in observed stellar flux in the Upper Scorpius and $\\rho$ Ophiuchus star formation regions with the Kepler mission by Ansdell et al. primarily identified young, low mass stars (dippers) with low accretion rates and hosting moderately evolved dusty circumstellar disks. These young stars likely exhibit rotating star spots that cause quasi-periodic photometric variations. However, a separate period associated with the dips is not evident in spectrograms constructed from the light curves. The material causing the dips in most of these light curves must be approximately corotating with the star. We find that disk temperatures computed at the disk corotation radius are cool enough that dust should not sublimate. Dippers are preferentially associated with young, low mass stars as they have low enough luminosities to allow dust to survive within a few stellar radii. Crude estimates for stellar magnetic field strengths and accretion rates are consistent with magnetospheric truncation near the corotat...
Pattern phenomena in an rf discharge dusty plasma system
Institute of Scientific and Technical Information of China (English)
HUANG Feng; YE Maofu; WANG Long
2006-01-01
Various dust patterns are observed in an rf discharge dusty plasma system.According to the dust growth process from small to large in size, the formation of different dust patterns can be divided into two stages: the small-particle stage (or dust cloud stage),and the large-particle stage (or dust crystal stage). The evolution relations between different dust patterns with gas pressure changing are investigated. Dust voids, dust acoustic waves and strong turbulence modes are presented at the small-particle stage. The self-organized dust lattices and dust clusters are investigated at the large-particle stage.The static structure of a dust lattice is characterized by means of the pair correlation function. Dust clusters formed by particles with different numbers and the regular evolution of the clusters with gas pressure are also investigated. The packing sequences of dust clusters are verified through two-dimensional confined molecular dynamics simulations.
Evolution of Dusty Disks in Nearby Young Stellar Groups
Jayawardhana, R
2001-01-01
Given their proximity and age differences, nearby groups of young stars are valuable laboratories for investigations of disk evolution and diversity. The estimated 10-Myr age of groups like the TW Hydrae Association provides a strong constraint on disk evolution timescales and fills a significant gap in the age sequence between 1-Myr-old T Tauri stars in molecular clouds and 50-Myr-old nearby open clusters. I review the results of recent and on-going studies of dusty disks in three nearby groups --TW Hya, $\\eta$ Cha and MBM 12-- that suggest rapid evolution of inner disks. However, it is unlikely that there is a universal evolutionary timescale for protoplanetary disks, especially when the influence of companion stars is taken into account.
Dusty plasma processes in Earth's polar summer mesosphere
Popel, S. I.; Dubinsky, A. Yu.; Dubinsky
2013-08-01
A self-consistent model for the description of dusty plasma structures, such as noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE), which are frequently grouped together under the common term polar mesospheric clouds, is presented. The model takes into account the processes of condensation of water vapor, ionization, recombination, action of solar radiation, sedimentation, dust particle growth, dust particle charging, electric fields, etc. Using the model, we explain the basic data of observations on the behavior of charged component in polar summer mesosphere. Furthermore, we show the influence of initial distributions of fine particles as well as that of the processes of condensation and water molecule absorption by fine particles on the formation of NLC and PMSE. We also illustrate the possibility of the formation of layered structure and sharp boundaries of NLC.
ITER ECRH Upper Launcher: Test plan for qualification of the Diamond Torus Window Prototype III
Energy Technology Data Exchange (ETDEWEB)
Schreck, Sabine, E-mail: sabine.schreck@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Aiello, Gaetano; Meier, Andreas; Strauss, Dirk [Karlsruhe Institute of Technology, Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Gagliardi, Mario; Saibene, Gabriella [F4E, Antennas and Plasma Engineering, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Scherer, Theo [Karlsruhe Institute of Technology, Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
2016-11-01
Highlights: • A qualification program for the ITER diamond torus window is being developed. • The testing program for the qualification of the bare diamond disk is defined. • First qualification tests show a very good quality of the diamond disk prototypes. - Abstract: The diamond window is part of the electron cyclotron heating upper launcher system for ITER. Together with the isolation valve it constitutes the primary vacuum boundary and it also acts as first tritium barrier. Therefore the window is classified as Safety/Protection Important Component (SIC/PIC) with the nuclear safety function “confinement”. As the diamond window unit is not entirely covered by standard codes, an ad-hoc qualification program needs to be defined, including analysis, prototyping and testing. In the framework of a contract with F4E, the test program for a diamond window prototype is being developed with the aim to prove its operability for normal, accidental and incidental conditions as identified in the ITER load specifications. Tests range from dielectric loss measurements for the bare Chemical Vapour Deposition (CVD) diamond disk up to mechanical and vacuum tests for the complete window assembly. Finally mm-wave properties have to be characterized for the complete window. A clear definition of the testing requirements and of the acceptance criteria is necessary as well as a complete documentation of the process. This paper will present the development of the test plan for a window prototype, which is currently under manufacturing. First tests are directed to the characterization of the bare diamond disk with a focus on its dielectric properties.
Dusty disks around central stars of planetary nebulae
Energy Technology Data Exchange (ETDEWEB)
Clayton, Geoffrey C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); De Marco, Orsola [Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia); Nordhaus, Jason [Center for Computational Relativity and Gravitation, and National Technical Institute for the Deaf, Rochester Institute of Technology, Rochester, NY 14623 (United States); Green, Joel [Department of Astronomy, The University of Texas, 1 University Station, C1400, Austin, TX 78712-0259 (United States); Rauch, Thomas; Werner, Klaus [Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Sand 1, D-72076 Tübingen (Germany); Chu, You-Hua, E-mail: gclayton@fenway.phys.lsu.edu, E-mail: orsola@science.mq.edu.au, E-mail: nordhaus@astro.rit.edu, E-mail: joel@astro.as.utexas.edu, E-mail: rauch@astro.uni-tuebingen.de, E-mail: werner@astro.uni-tuebingen.de, E-mail: chu@astro.uiuc.edu [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)
2014-06-01
Only a few percent of cool, old white dwarfs (WDs) have infrared excesses interpreted as originating in small hot disks due to the infall and destruction of single asteroids that come within the star's Roche limit. Infrared excesses at 24 μm were also found to derive from the immediate vicinity of younger, hot WDs, most of which are still central stars of planetary nebulae (CSPNe). The incidence of CSPNe with this excess is 18%. The Helix CSPN, with a 24 μm excess, has been suggested to have a disk formed from collisions of Kuiper belt-like objects (KBOs). In this paper, we have analyzed an additional sample of CSPNe to look for similar infrared excesses. These CSPNe are all members of the PG 1159 class and were chosen because their immediate progenitors are known to often have dusty environments consistent with large dusty disks. We find that, overall, PG 1159 stars do not present such disks more often than other CSPNe, although the statistics (five objects) are poor. We then consider the entire sample of CSPNe with infrared excesses and compare it to the infrared properties of old WDs, as well as cooler post-asymptotic giant branch (AGB) stars. We conclude with the suggestion that the infrared properties of CSPNe more plausibly derive from AGB-formed disks rather than disks formed via the collision of KBOs, although the latter scenario cannot be ruled out. Finally, there seems to be an association between CSPNe with a 24 μm excess and confirmed or possible binarity of the central star.
Shock jump relations for a dusty gas atmosphere
Anand, R. K.
2014-01-01
This paper presents simplified forms of jump relations for one dimensional shock waves propagating in a dusty gas. The dusty gas is assumed to be a mixture of a perfect gas and spherically small solid particles, in which solid particles are continuously distributed. The simplified jump relations for the pressure, the temperature, the density, the velocity of the mixture and the speed of sound have been derived in terms of the upstream Mach number. The expressions for the adiabatic compressibility of the mixture and the change-in-entropy across the shock front have also been derived in terms of the upstream Mach number. Further, the handy forms of shock jump relations have been obtained in terms of the initial volume fraction of small solid particles and the ratio of specific heats of the mixture, simultaneously for the two cases viz., (i) when the shock is weak and, (ii) when it is strong. The simplified shock jump relations reduce to the Rankine-Hugoniot conditions for shock waves in an ideal gas when the mass fraction (concentration) of solid particles in the mixture becomes zero. Finally, the effects due to the mass fraction of solid particles in the mixture, and the ratio of the density of solid particles to the initial density of the gas are studied on the pressure, the temperature, the density, the velocity of the mixture, the speed of sound, the adiabatic compressibility of the mixture and the change-in-entropy across the shock front. The results provided a clear picture of whether and how the presence of dust particles affects the flow field behind the shock front. The aim of this paper is to contribute to the understanding of how the shock waves behave in the gas-solid particle two-phase flows.
On Radiation Pressure in Static, Dusty H II Regions
Draine, B. T.
2011-05-01
Radiation pressure acting on gas and dust causes H II regions to have central densities that are lower than the density near the ionized boundary. H II regions in static equilibrium comprise a family of similarity solutions with three parameters: β, γ, and the product Q 0 n rms; β characterizes the stellar spectrum, γ characterizes the dust/gas ratio, Q 0 is the stellar ionizing output (photons/s), and n rms is the rms density within the ionized region. Adopting standard values for β and γ, varying Q 0 n rms generates a one-parameter family of density profiles, ranging from nearly uniform density (small Q 0 n rms) to shell-like (large Q 0 n rms). When Q 0 n rms >~ 1052 cm-3 s-1, dusty H II regions have conspicuous central cavities, even if no stellar wind is present. For given β, γ, and Q 0 n rms, a fourth quantity, which can be Q 0, determines the overall size and density of the H II region. Examples of density and emissivity profiles are given. We show how quantities of interest—such as the peak-to-central emission measure ratio, the rms-to-mean density ratio, the edge-to-rms density ratio, and the fraction of the ionizing photons absorbed by the gas—depend on β, γ, and Q 0 n rms. For dusty H II regions, compression of the gas and dust into an ionized shell results in a substantial increase in the fraction of the stellar photons that actually ionize H (relative to a uniform-density H II region with the same dust/gas ratio and density n = n rms). We discuss the extent to which radial drift of dust grains in H II regions can alter the dust-to-gas ratio. The applicability of these solutions to real H II regions is discussed.
Oi, Nagisa; Imanishi, Masatoshi; Imase, Keisuke
2010-12-01
We present near-infrared K- (1.9-2.5μm) and L- (2.8-4.2μm) band spectroscopy of 22 Seyfert nuclei. We used two methods to investigate the presence of nuclear starbursts: (1) the Polycyclic Aromatic Hydrocarbon (PAH) emission feature at λrest = 3.3μm in the rest frame of the K-band spectrum (a starburst indicator) and (2) the CO absorption feature at λrest = 2.3-2.4μm in the rest frame of the K-band spectrum, originating in the CO molecule. We clearly detected the 3.3μm PAH emission features in five objects and the CO absorption features in 17 objects. Seyfert 2 galaxies tend to show bluer K - L colors compared with Seyfert 1 galaxies. We interpret the discrepancy as resulting from the relative strength of stellar emission because AGN emission is affected by dust extinction. The 3.3μm PAH emission luminosity (L3.3PAH) distributions for the Seyfert 1s and Seyfert 2s are very similar when normalized to the AGN power. The star-formation rates estimated from L3.3PAH could be large enough to inflate the dusty torus by a supernova explosion. We find that L3.3PAH positively correlates with the N-band luminosity with small aperture over a wide AGN luminosity range, and is independent of the physical area we probed. The results suggest that the nuclear region has a concentration of star formation and it would control the AGN activity.
Magalhaes, F. P.; Lopes, R. M. C.; Rathbun, J. A.; Gonzalez, W. D.; Morgenthaler, J. P.; Echer, E.; Echer, M. P. D. S.
2015-12-01
Io, the innermost of the Jupiter's four Galilean moons, is a remarkable object in the Solar System, due to its intense and energetic volcanic activity. The volcanic sulfur and oxygen in Io's tenuous atmosphere escapes forming an extended neutral cloud around Io and Jupiter. Subsequently, by ionization and pickup ions, a ring of charged particles encircling Jupiter is created, forming the Io plasma torus. Considering this scenario, it is reasonable to expect that the Io plasma torus should be affected by changes in Io's volcanism. Interactions between Io and the Jovian environment is unique and yet not very well understood. Here we present two sets of observations. One from the Galileo Near-Infrared Imaging Spectrograph (NIMS) instrument, which obtained spectral image cubes between 0.7 and 5.2 microns. The other dataset is from ground-based observations of the [SII] 6731 Å emission lines from the Io plasma torus, obtained at McMath-Pierce Solar Telescope, at Kitt Peak. Our dataset from the [SII] 6731 Å emission lines cover more years than the one from the NIMS data. The years presented in this work for a comparative study are from 1998 through 2001. Using the NIMS instrument we were able to identify which volcanoes were active and measure their level of activity. From the [SII] 6731 Å emission lines we were able to trace the densest part of the torus and also the brightness of both ansa. By comparing the results from the Galileo instrument and the ground-based observations, we are exploring how the Io plasma torus responds to large eruptions from Io. We aim with this study to help improve our understanding of this complex coupled system, Jupiter-Io.
Visualizing a Dusty Plasma Shock Wave via Interacting Multiple-Model Mode Probabilities
Oxtoby, Neil P.; Ralph, Jason F.; Durniak, Céline; Samsonov, Dmitry
2011-01-01
Particles in a dusty plasma crystal disturbed by a shock wave are tracked using a three-mode interacting multiple model approach. Color-coded mode probabilities are used to visualize the shock wave propagation through the crystal.
Thermoluminescence measurements of neutron streaming through JET Torus Hall ducts
Energy Technology Data Exchange (ETDEWEB)
Obryk, Barbara, E-mail: barbara.obryk@ifj.edu.pl [Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland); Batistoni, Paola [Associazione EURATOM-ENEA sulla Fusione, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); EURATOM–CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Conroy, Sean [EURATOM-VR Association, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala (Sweden); EURATOM–CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Syme, Brian D.; Popovichev, Sergey [EURATOM–CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Stamatelatos, Ion E.; Vasilopoulou, Theodora [Institute of Nuclear and Radiological Sciences, Energy, Technology and Safety, NCSR “Demokritos”, Athens (Greece); Bilski, Paweł [Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland)
2014-10-15
Highlights: •Thermoluminescence detectors (TLDs) were used for dose measurements at JET. •Pairs of {sup 6}LiF/{sup 7}LiF TLDs allow to measure thermal neutron component of a radiation field. •For detection of neutrons of higher energy, polyethylene (PE-300) moderators were used. •TLDs were installed at eleven positions in the JET hall and the hall labyrinth. •The experimental results are compared with calculations using the MCNP code. -- Abstract: Thermoluminescence detectors (TLD) were used for dose measurements at JET. Several hundreds of LiF detectors of various types, standard LiF:Mg,Ti and highly sensitive LiF:Mg,Cu,P were produced. LiF detectors consisting of natural lithium are sensitive to slow neutrons, their response to neutrons being enhanced by {sup 6}Li-enriched lithium or suppressed by using lithium consisting entirely of {sup 7}Li. Pairs of {sup 6}LiF/{sup 7}LiF detectors allow distinguishing between neutron/non-neutron components of a radiation field. For detection of neutrons of higher energy, polyethylene (PE-300) moderators were used. TLDs, located in the centre of cylindrical moderators, were installed at eleven positions in the JET hall and the hall labyrinth in July 2012, and exposure took place during the last two weeks of the experimental campaign. Measurements of the gamma dose were obtained for all positions over a range of about five orders of magnitude variation. As the TLDs were also calibrated in a thermal neutron field, the neutron fluence at the experimental position could be derived. The experimental results are compared with calculations using the MCNP code. The results confirm that the TLD technology can be usefully applied to measurements of neutron streaming through JET Torus Hall ducts.
Particle position and velocity measurement in dusty plasmas using particle tracking velocimetry
Feng, Yan; Goree, J.; Haralson, Zach; Wong, Chun-Shang; Kananovich, A.; Li, Wei
2016-06-01
> Methods of imaging and image analysis are presented for dusty plasma experiments. Micron-sized polymer spheres, electrically suspended in a partially ionized gas, are illuminated by a sheet of laser light and imaged by video cameras. Image analysis methods yield particle positions and velocities of individual particles in each video image. Methods to minimize errors in the particle positions and velocities, which are now commonly used in the dusty plasma community, are described.
Cassini capturing of freshly-produced water-group ions in the Enceladus torus
Yaroshenko, V. V.; Miloch, W. J.; Thomas, H. M.; Morfill, G. E.
2012-09-01
The water vapor plume on the geological-active south-polar region of the moon Enceladus is recognized as the main source of Saturn's neutral torus centered on the Enceladus orbit. The composition of the torus is dominated by water group species. Recent in situ Cassini plasma spectrometer measurements indicate the existence of freshly produced, slow and non-thermalized water group ions throughout the Enceladus torus including regions far from the moon. We report the results of modeling spacecraft-plasma interactions in the environment relevant for the Enceladus torus to show that new-born non-thermalized ions will inevitably be captured by the electric fields arising around the charged spacecraft. The associated plasma configuration can directly impact the plasma measurements and thus is important for reliable interpretation of data obtained by Cassini instruments in the Enceladus torus. The simulation results appear to be partially supported by Cassini observations and can provide new insights into intricate process of Enceladus-plasma interactions.
King, Chih-Hung; Chen, Tiffany L; Fan, Zhengqin; Glass, Jonathan D; Kemp, Charles C
2012-03-01
People with physical disabilities have ranked object retrieval as a high-priority task for assistive robots. We have developed Dusty, a teleoperated mobile manipulator that fetches objects from the floor and delivers them to users at a comfortable height. In this paper, we first demonstrate the robot's high success rate (98.4%) when autonomously grasping 25 objects considered being important by people with amyotrophic lateral sclerosis (ALS). We tested the robot with each object in five different configurations on five types of flooring. We then present the results of an experiment in which 20 people with ALS operated Dusty. Participants teleoperated Dusty to move around an obstacle, pick up an object and deliver the object to themselves. They successfully completed this task in 59 out of 60 trials (3 trials each) with a mean completion time of 61.4 SD = 20.5 seconds), and reported high overall satisfaction using Dusty (7-point Likert scale; 6.8 SD = 0.6). Participants rated Dusty to be significantly easier to use than their own hands, asking family members, and using mechanical reachers (p < 0.03, paired t-tests). Fourteen of the 20 participants reported that they would prefer using Dusty over their current methods. [Box: see text].
On the nature of S II emission from Jupiter's hot plasma torus
Brown, R. A.; Shemansky, D. E.
1982-01-01
An effective electron temperature T(e) of 80,000 K is indicated by the Voyager 1 encounter Jupiter hot torus emission rates in the 6731, 1256, 911 and reclassified 765 A transitions of S II. A set of 53 measurements of the S II red line doublet obtained at 5.9 Jupiter radii shows strong, irregular fluctuations in intensity, but no variation in the line ratio. At this distance from Jupiter, the torus is found to be longitudinally uniform in density; this is consonant with Voyager UVS findings, but contrary to magnetic anomaly model predictions. It is suggested that presently unidentified ion-ion and/or iron-atom reactions are responsible for the S II component irregular variations, in view of the fact that electron properties are regular and variable only over a small range in the hot torus at 5.9 Jupiter radii.
Piatek, Marcin
2014-01-01
In this work the correspondence between the semiclassical limit of the DOZZ quantum Liouville theory on the torus and the Nekrasov-Shatashvili limit of the N=2* (Omega-deformed) U(2) super-Yang-Mills theory is exploited to propose new formulae for the accessory parameter of the Lame equation. It has been found that the Lame accessory parameter is determined by the classical Liouville action on the one-punctured torus or more concretely by the torus classical block evaluated on the saddle point intermediate classical weight. Moreover, as an implication of the aforementioned correspondence it has been obtained that the accessory parameter is related to the sum of all rescaled column lengths of the so-called "critical" Young diagrams extremizing the instanton "free energy". Finally, it has been pointed out that the sum over the "critical" column lengths can be rewritten in terms of a contour integral in which the integrand is built out of certain special functions.
Stability of small-amplitude torus knot solutions of the localized induction approximation
Energy Technology Data Exchange (ETDEWEB)
Calini, Annalisa; Ivey, Thomas, E-mail: calinia@cofc.edu [Department of Mathematics, College of Charleston, Charleston, SC 29424 (United States)
2011-08-19
We study the linear stability of small-amplitude torus knot solutions of the localized induction approximation equation for the motion of a thin vortex filament in an ideal fluid. Such solutions can be constructed analytically through the connection with the focusing nonlinear Schroedinger equation using the method of isoperiodic deformations. We show that these (p, q) torus knots are generically linearly unstable for p < q, while we provide examples of neutrally stable (p, q) torus knots with p > q, in contrast with an earlier linear stability study by Ricca (1993 Chaos 3 83-95; 1995 Chaos 5 346; 1995 Small-scale Structures in Three-dimensional Hydro and Magneto-dynamics Turbulence (Lecture Notes in Physics vol 462) (Berlin: Springer)). We also provide an interpretation of the original perturbative calculation in Ricca (1995), and an explanation of the numerical experiments performed by Ricca et al (1999 J. Fluid Mech. 391 29-44), in light of our results.
Effect of enclosed fluid on the dynamic response of inflated torus
Srivastava, Ashish; Mishra, B. K.; Jain, S. C.
2008-01-01
Large inflatable structures have been the subject of renewed interest for scientists/engineers in recent years due to their potential space applications such as communication antennas, solar thermal propulsion and space solar power. The major advantages of using inflatable structures in space are their extremely low-weight, on-orbit deployability and inherent low launch volume. An inflated torus is a key component of many inflated space structures such as a thin membrane reflector. In view of their importance, structural static and dynamic behavior of inflated torus need to be investigated. In order to develop a more realistic model, dynamic interaction between the enclosed fluid and the torus has been included in the present work. An appreciable decrease in the modal frequencies is observed when fluid-structure interaction is taken into account. Some additional modes are also obtained. It is concluded that fluid-structure interaction significantly affects the dynamic behavior of inflatable space structures.
Embedding global and collective in a torus network with message class map based tree path selection
Chen, Dong; Coteus, Paul W.; Eisley, Noel A.; Gara, Alan; Heidelberger, Philip; Senger, Robert M; Salapura, Valentina; Steinmacher-Burow, Burkhard; Sugawara, Yutaka; Takken, Todd E.
2016-06-21
Embodiments of the invention provide a method, system and computer program product for embedding a global barrier and global interrupt network in a parallel computer system organized as a torus network. The computer system includes a multitude of nodes. In one embodiment, the method comprises taking inputs from a set of receivers of the nodes, dividing the inputs from the receivers into a plurality of classes, combining the inputs of each of the classes to obtain a result, and sending said result to a set of senders of the nodes. Embodiments of the invention provide a method, system and computer program product for embedding a collective network in a parallel computer system organized as a torus network. In one embodiment, the method comprises adding to a torus network a central collective logic to route messages among at least a group of nodes in a tree structure.
Universal Behaviour on the Break-up of the Spiral Mean Torus
Institute of Scientific and Technical Information of China (English)
周济林; 胡斑比; 孙义燧
2001-01-01
We study numerically the critical behaviour during the break-up of the spiral mean torus in a four-dimensional symplectic map. At each point of the parameter space, the stability indices of a serial of periodic orbits are calculated with their winding numbers approaching the spiral mean torus. The critical values of the parameters when the torus breaks are determined by the criterion that the variance of the distribution on the indices reaches a minimum. Some evidence is revealed about the possible existence of a universal distribution on the stability indices of the periodic orbits at the critical This confirms the picture given by the approximate renormalization theory of the Hamiltonian systems with three degrees of freedom.
The sub-arcsecond dusty environment of Eta Carinae
Chesneau, O.; Min, M.; Herbst, T.; Waters, L. B. F. M.; Leinert, Ch.; Hillier, D. J.
2005-09-01
The core of the nebula surrounding Eta Carinae was observed with the VLT Adaptive Optics system NACO and with the interferometer VLTI/MIDI to spatially and spectrally isolate the warm dusty environment and the central object. Narrow-band images at 3.74 μm and 4.05 μm reveal a butterfly shaped dusty environment close to the central star with unprecedented spatial resolution. Fringes have been obtained in the Mid-IR and a correlated flux of about 100 Jy situated 0.3 arcsec south-east from the photocenter of the nebula at 8.7 μm is detected. This flux is partly attributed to the central object and provides an upper limit for the SED of the central source from 3.8 μm to 13.5 μm. We have been able to spectrally disperse the signal from the nebula itself at PA=318 degree, i.e. in the direction of the bipolar nebula (˜310°) within the MIDI field of view of 3 arcsec. A large amount of corundum (Al2O3) is discovered, peaking at 0.6-1.2 arcsec south-east from the star, whereas the dust content of the Weigelt blobs, in the equatorial plane, is dominated by silicates. We propose a geometry for the Butterfly nebulae assuming a similar axis for the large and little Homunculus. We suggest that the Butterfly nebulae is a consequence of the 1890 outburst and is embedded in the Little Homonculus its geometry is, mostly shaped by the local dust formation conditions which are directly affected by the latitudinal dependance of the ejection and the present wind. The dust is mostly formed in the bright rims of the Butterfly nebula. The dust condenses closer to the poles of the star owing to the larger mass-loss rate and the relative velocity between the stellar wind and the ejecta at these latitudes. In this geometry, the bright southern clump directly sees the southern pole of the central object. At intermediate latitudes, the mass-loss rate and the relative velocity of the wind are decreased and dust forms further out. We suggest that the survival and the large mass of the
Coulomb-influenced collisions in aerosols and dusty plasmas.
Gopalakrishnan, Ranganathan; Hogan, Christopher J
2012-02-01
In aerosol and dusty plasma systems, the behavior of suspended particles (grains) is often strongly influenced by collisions occurring between ions and particles, as well as between particles themselves. In determining the collision kernel or collision rate coefficient for such charged entities, complications arise in that the collision process can be completely described neither by continuum transport mechanics nor by free molecular (ballistic) mechanics; that is, collisions are transition regime processes. Further, both the thermal energy and the potential energy between colliding entities can strongly influence the collision rate and must be considered. Flux-matching theory, originally developed by Fuchs, is frequently applied for calculation of collision rate coefficients under these circumstances. However, recent work suggests that crucial assumptions in flux-matching theory are not appropriate to describe transition regime collisions in the presence of potential interactions. Here, we combine dimensional analysis and mean first passage time calculations to infer the collision kernel between dilute charged entities suspended in a light background gas at thermal equilibrium. The motion of colliding entities is described by a Langevin equation, and Coulombic interactions are considered. It is found that the dimensionless collision kernel for these conditions, H, is a function of the diffusive Knudsen number, Kn(D) (in contrast to the traditional Knudsen number), and the potential energy to thermal energy ratio, Ψ(E). For small and large Kn(D), it is found that the dimensionless collision kernels inferred from mean first passage time calculations collapse to the appropriate continuum and free molecular limiting forms, respectively. Further, for repulsive collisions (Ψ(E) negative) or attractive collisions with Ψ(E)0.5, it is found that flux-matching theory predictions substantially underestimate the collision kernel. We find that the collision process in this
Holzenspies, P.K.F.; Schepers, Erik; Bach, Wouter; Jonker, Mischa; Sikkes, Bart; Smit, Gerardus Johannes Maria; Havinga, Paul J.M.
2003-01-01
Routing on a two-dimensional torus architecture by means of the wormhole routing algorithm is introduced and extended to an n-dimensional torus model. To prevent blocking deadlocks caused by this algorithm, a multiple virtual channel solution is introduced. An implementation of virtual channels is
Overview of Results from the National Spherical Torus Experiment (NSTX)
Energy Technology Data Exchange (ETDEWEB)
Gates, D; Ahn, J; Allain, J; Andre, R; Bastasz, R; Bell, M; Bell, R; Belova, E; Berkery, J; Betti, R; Bialek, J; Biewer, T; Bigelow, T; Bitter, M; Boedo, J; Bonoli, P; Bozzer, A; Brennan, D; Breslau, J; Brower, D; Bush, C; Canik, J; Caravelli, G; Carter, M; Caughman, J; Chang, C; Choe, W; Crocker, N; Darrow, D; Delgado-Aparicio, L; Diem, S; D' Ippolito, D; Domier, C; Dorland, W; Efthimion, P; Ejiri, A; Ershov, N; Evans, T; Feibush, E; Fenstermacher, M; Ferron, J; Finkenthal, M; Foley, J; Frazin, R; Fredrickson, E; Fu, G; Funaba, H; Gerhardt, S; Glasser, A; Gorelenkov, N; Grisham, L; Hahm, T; Harvey, R; Hassanein, A; Heidbrink, W; Hill, K; Hillesheim, J; Hillis, D; Hirooka, Y; Hosea, J; Hu, B; Humphreys, D; Idehara, T; Indireshkumar, K; Ishida, A; Jaeger, F; Jarboe, T; Jardin, S; Jaworski, M; Ji, H; Jung, H; Kaita, R; Kallman, J; Katsuro-Hopkins, O; Kawahata, K; Kawamori, E; Kaye, S; Kessel, C; Kim, J; Kimura, H; Kolemen, E; Krasheninnikov, S; Krstic, P; Ku, S; Kubota, S; Kugel, H; La Haye, R; Lao, L; LeBlanc, B; Lee, W; Lee, K; Leuer, J; Levinton, F; Liang, Y; Liu, D; Luhmann, N; Maingi, R; Majeski, R; Manickam, J; Mansfield, D; Maqueda, R; Mazzucato, E; McCune, D; McGeehan, B; McKee, G; Medley, S; Menard, J; Menon, M; Meyer, H; Mikkelsen, D; Miloshevsky, G; Mitarai, O; Mueller, D; Mueller, S; Munsat, T; Myra, J; Nagayama, Y; Nelson, B; Nguyen, X; Nishino, N; Nishiura, M; Nygren, R; Ono, M; Osborne, T; Pacella, D; Park, H; Park, J; Paul, S; Peebles, W; Penaflor, B; Peng, M; Phillips, C; Pigarov, A; Podesta, M; Preinhaelter, J; Ram, A; Raman, R; Rasmussen, D; Redd, A; Reimerdes, H; Rewoldt, G; Ross, P; Rowley, C; Ruskov, E; Russell, D; Ruzic, D; Ryan, P; Sabbagh, S; Schaffer, M; Schuster, E; Scott, S; Shaing, K; Sharpe, P; Shevchenko, V; Shinohara, K; Sizyuk, V; Skinner, C; Smirnov, A; Smith, D; Smith, S; Snyder, P; Soloman, W; Sontag, A; Soukhanovskii, V; Stoltzfus-Dueck, T; Stotler, D; Strait, T; Stratton, B; Stutman, D; Takahashi, R; Takase, Y; Tamura, N; Tang, X; Taylor, G; Taylor, C; Ticos, C; Tritz, K; Tsarouhas, D; Turrnbull, A; Tynan, G; Ulrickson, M; Umansky, M; Urban, J; Utergberg, E; Walker, M; Wampler, W; Wang, J; Wang, W; Weland, A
2009-01-05
The mission of NSTX is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high {beta} operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale-length. Results from n = 3 braking studies confirm the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of High Harmonic Fast-Waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance l{sub i} {approx} 0.4 with strong shaping ({kappa} {approx} 2.7, {delta} {approx} 0.8) with {beta}{sub N} approaching the with-wall beta limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction f{sub NI} {approx} 71%. Instabilities driven by super-Alfvenic ions are an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvenic. Linear TAE thresholds and appreciable fast-ion loss during multi-mode bursts are measured and these results are compared to theory. RWM/RFA feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with {beta} above the no-wall limit. The impact of n > 1 error fields on stability is a important result for ITER. Other highlights are
Overview of Results from the National Spherical Torus Experiment (NSTX)
Energy Technology Data Exchange (ETDEWEB)
Gates, D. A.; Ahn, J.; Allain, J.; Andre, R.; Bastasz, R.; Bell, M.; Bell, R.; Belova, E.; Berkery, J.; Betti, R.; Bialek, J.; Biewer, T.; Bigelow, T.; Bitter, M.; Choe, W.; Crocker, N.; Darrow, D.; Delgado-Aparicio, L.; Diem, S.; D’Ippolito, D.; Domier, C.; Dorland, W.; Efthimion, P.; Ejiri, A.; Ershov, N.; Evans, T.; Feibush, E.; Fenstermacher, M.; Ferron, J.; Finkenthal, M.; Foley, J.; Frazin, R.; Fredrickson, E.; Fu, G.; Funaba, H.; Gerhardt, S.; Glasser, A.; Gorelenkov, N.; Grisham, L.; Hahm, T.; Harvey, R.; Hassanein, A.; Heidbrink, W.; Hill, K.; Hillesheim, J.; Hillis, D.; Hirooka, Y.; Hu, B.; Humphreys, D.; Idehara, T.; Indireshkumar, K.; Ishida, A.; Jaeger, F.; Jarboe, T.; Jardin, S.; Jaworski, M.; Ji, H.; Jung, H.; Kaita, R.; Kallman, J.; Katsuro-Hopkins, O.; Kawahata, K.; Kawamori, E.; Kaye, S.; Kessel, C.; Kim, J.; Kimura, H.; Kolemen, E.; Krasheninnikov, S.; Krstic, P.; Ku, S.; Kubota, S.; Kugel, H.; La Haye, R.; Lao, L.; LeBlanc, B.; Lee, W.; Lee, K.; Leuer, J.; Levinton, F.; Liang, Y.; Liu, D.; Luhmann, Jr., N.; Maingi, R.; Majeski, R.; Manickam, J.; Mansfield, D.; Maqueda, R.; Mazzucato, E.; McCune, D.; McGeehan, B.; McKee, G.; Medley, S.; Menard, J.; Menon, M.; Meyer, H.; Mikkelsen, D.; Miloshevsky, G.; Mitarai, O.; Mueller, D.; Mueller, S.; Munsat, T.; Myra, J.; Nagayama, Y.; Nelson, B.; Nguyen, X.; Nishino, N.; Nishiura, M.; Nygren, R.; Ono, M.; Osborne, T.; Pacella, D.; Park, H.; Park, J.; Paul, S.; Peebles, W.; Penaflor, B.; Peng, M.; Phillips, C.; Pigarov, A.; Podesta, M.; Preinhaelter, J.; Ram, A.; Raman, R.; Rasmussen, D.; Redd, A.; Reimerdes, H.; Rewo, G.; Ross, P.; Rowley, C.; Ruskov, E.; Russell, D.; Ruzic, D.; Ryan, P.; Sabbagh, S.; Schaffer, M.; Schuster, E.; Scott, S.; Shaing, K.; Sharpe, P.; Shevchenko, V.; Shinohara, K.; Sizyuk, V.; Skinner, C.; Smirnov, A.; Smith, D.; Smith, S.; Snyder, P.; Solomon, W.; Sontag, A.; Soukhanovskii, V.; Stoltzfus-Dueck, T.; Stotler, D.; Strait, T.; Stratton, B.; Stutman, D.; Takahashi, R.; Takase, Y.; Tamura, N.; Tang, X.; Taylor, G.; Taylor, C.; Ticos, C.; Tritz, K.; Tsarouhas, D.; Turrnbull, A.; Tynan, G.; Ulrickson, M.; Umansky, M.; Urban, J.; Utergberg, E.; Walker, M.; Wampler, W.; Wang, J.; Wang, W.; Welander, A.; Whaley, J.; White, R.; Wilgen, J.; Wilson, R.; Wong, K.; Wright, J.; Xia, Z.; Xu, X.; Youchison, D.; Yu, G.; Yuh, H.; Zakharov, L.; Zemlyanov, D.; Zweben, S.
2009-03-24
The mission of NSTX is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale-length. Results from n = 3 braking studies are consistent with the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of High Harmonic Fast-Waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap current fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance l_{i} ~0.4 with strong shaping (κ ~ 2.7, δ ~ 0.8) with β_{N} approaching the with-wall beta limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction f_{NI} ~71%. Instabilities driven by super-Alfv´enic ions will be an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfv´enic. Linear TAE thresholds and appreciable fast-ion loss during multi-mode bursts are measured and these results are compared to theory. The impact of n > 1 error fields on stability is a important result for ITER. RWM/RFA feedback combined with n=3 error field control was used on NSTX to maintain plasma rotation with β above the no-wall limit. Other highlights are: results
Energy Technology Data Exchange (ETDEWEB)
Duan Jizheng; Wang Canglong; Zhang Jianrong; Ma Shengqian; Hong Xueren; Sun Jianan [College of Physics and Electronic Engineering and Joint Laboratory of Atomic and Molecular Physics of NWNU and IMP CAS, Northwest Normal University, Lanzhou 730070 (China) and Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Duan Wenshan [College of Physics and Electronic Engineering and Joint Laboratory of Atomic and Molecular Physics of NWNU and IMP CAS, Northwest Normal University, Lanzhou 730070 (China) and Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Yang Lei [College of Physics and Electronic Engineering and Joint Laboratory of Atomic and Molecular Physics of NWNU and IMP CAS, Northwest Normal University, Lanzhou 730070 (China) and Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Department of Physics, Lanzhou University, Lanzhou 730000 (China)
2012-08-15
The effects of dust size distribution and charging process of dust grains on the complex electric conductivity of dusty plasmas have been investigated in the present paper. Comparisons are made between real dusty plasma in which there are many different dust grain species and the mono-sized dusty plasma (MDP) in which there is only one kind of dust grain whose size is the average dust size. In some cases the complex electric conductivity of real dusty plasma is larger than that of MDP, while in other cases it is smaller than that of MDP, it depends on the dust size distribution function.
Zeros of the Jones Polynomial for Torus Knots and 2-bridge Knots
Institute of Scientific and Technical Information of China (English)
HAN You-fa; ZHANG Rong-wei; WANG Lin-lin; MA Xiao-sha
2014-01-01
We study zeros of the Jones polynomial and their distributions for torus knots and 2-bridge knots. We prove that e(2m+1)πi/2 and e(2m+1)πi/4(m is a positive integer) can not be the zeros of Jones polynomial for torus knots Tp,q by the knowledge of the trigonometric function. We elicit the normal form of Jones polynomials of the 2-bridge knot C (−2, 2, · · · , (−1)r 2) by the recursive form and discuss the distribution of their zeros.
From Canards of Folded Singularities to Torus Canards in a Forced van der Pol Equation
DEFF Research Database (Denmark)
Burke, John; Desroches, Mathieu; Granados, Albert;
2016-01-01
to the intermediate- and high-frequency forcing regimes and show that the forced van der Pol possesses torus canards instead. These torus canards consist of long segments near families of attracting and repelling limit cycles of the fast system, in alternation. We also derive explicit formulas for the parameter......-frequency periodically driven slow/fast systems with two fast variables and one slow variable which possess a non-degenerate fold of limit cycles. The analytic techniques used herein rely on geometric desingularisation, invariant manifold theory, Melnikov theory, and normal form methods. The numerical methods used...
Indian Academy of Sciences (India)
S S Kannan; S K Pattanayak
2009-09-01
In this paper, for any simple, simply connected algebraic group of type , or and for any maximal parabolic subgroup of , we describe all minimal dimensional Schubert varieties in $G/P$ admitting semistable points for the action of a maximal torus with respect to an ample line bundle on $G/P$. We also describe, for any semi-simple simply connected algebraic group and for any Borel subgroup of , all Coxeter elements for which the Schubert variety () admits a semistable point for the action of the torus with respect to a non-trivial line bundle on / .
The Coulomb gas representation of critical RSOS models on the sphere and the torus
Energy Technology Data Exchange (ETDEWEB)
Foda, O. (Rijksuniversiteit Utrecht (Netherlands). Inst. voor Theoretische Fysica); Nienhuis, B. (Rijksuniversiteit Leiden (Netherlands). Inst. Lorentz voor Theoretische Natuurkunde)
1989-10-02
We derive the Coulomb gas formulation of the c<1 discrete unitary series, on the sphere and the torus, starting from the corresponding regime-III RSOS models on a square lattice with appropriate topology. We clarify the origin of the background charge, the screening charges, and the choice of operator representations in a correlation function. In the scaling limit, we obtain a bosonic action coupled to the background curvature in addition to topological terms that vanish on the Riemann sphere. Its Virasoro algebra has the central charge expected on the basis of comparing conformal dimensions. As an application, we derive general expressions for the correlation functions on the torus. (orig.).
Influence of globalmagnetic perturbations on plasma behavior in Elmo Bumpy Torus
Energy Technology Data Exchange (ETDEWEB)
Quon, B.H.; Dandl, R.A.; Colestock, P.L.; :Bieniosek, F.M.; Ikegami, H.
1979-02-01
The sensitivity of plasma confinement to magnetic field error effects has been tested experimentally using externally introduced global field errors on the ELMO Bumpy Torus (EBT). Below a critical error field (deltaB/sub r//B)/sub cr/ of approx. = to 0.6-1 x 10/sup -3/ the plasma was observed to be essentially free from convective cells, toroidal currents, and instabilities. This observed critical value is comparable to a neoclassical critical field error (deltaB/sub r//B)/sub cr/ approx. = rho/R, the ratio of the ion Larmor radius to the major radius of the torus.
Mateos, S; Alonso-Herrero, A; Hernán-Caballero, A; Barcons, X; Ramos, A Asensio; Watson, M G; Blain, A; Caccianiga, A; Ballo, L; Braito, V; Almeida, C Ramos
2016-01-01
We present the distributions of geometrical covering factors of active galactic nuclei (AGNs) dusty tori (f2) using an X-ray selected complete sample of 227 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The AGN have z from 0.05 to 1.7, 2-10 keV luminosities between 10^42 and 10^46 erg/s and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS and the Wide-field Infrared Survey Explorer in a previous work we determined the rest-frame 1-20 microns continuum emission from the torus which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGN are intrinsically different, with type 2 AGN having on average tori with higher f2 than type 1 AGN. Nevertheless, ~20 per cent of type 1 AGN have tori with large covering factors while ~23-28 per cent of type 2 AGN have tori with small covering factors. Low f2 are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGN the effect is certainly small. f2 in...
Dusty Disks around White Dwarfs I: Origin of Debris Disks
Dong, Ruobing; Lin, D N C; Liu, X -W
2010-01-01
A significant fraction of the mature FGK stars have cool dusty disks at least an orders of magnitudes brighter than the solar system's outer zodiacal light. Since such dusts must be continually replenished, they are generally assumed to be the collisional fragments of residual planetesimals analogous to the Kuiper Belt objects. At least 10% of solar type stars also bear gas giant planets. The fraction of stars with known gas giants or detectable debris disks (or both) appears to increase with the stellar mass. Here, we examine the dynamical evolution of systems of long-period gas giant planets and residual planetesimals as their host stars evolve off the main sequence, lose mass, and form planetary nebula around remnant white dwarf cores. The orbits of distant gas giant planets and super-km-size planetesimals expand adiabatically. During the most intense AGB mass loss phase, sub-meter-size particles migrate toward their host stars due to the strong hydrodynamical drag by the intense stellar wind. Along their ...
Dusty gas with one fluid in smoothed particle hydrodynamics
Laibe, Guillaume
2014-01-01
In a companion paper we have shown how the equations describing gas and dust as two fluids coupled by a drag term can be reformulated to describe the system as a single fluid mixture. Here we present a numerical implementation of the one-fluid dusty gas algorithm using Smoothed Particle Hydrodynamics (SPH). The algorithm preserves the conservation properties of the SPH formalism. In particular, the total gas and dust mass, momentum, angular momentum and energy are all exactly conserved. Shock viscosity and conductivity terms are generalised to handle the two-phase mixture accordingly. The algorithm is benchmarked against a comprehensive suit of problems: dustybox, dustywave, dustyshock and dustyoscill, each of them addressing different properties of the method. We compare the performance of the one-fluid algorithm to the standard two-fluid approach. The one-fluid algorithm is found to solve both of the fundamental limitations of the two- fluid algorithm: it is no longer possible to concentrate dust below the ...
Electrostatic solitary waves in dusty pair-ion plasmas
Misra, A P
2013-01-01
The propagation of electrostatic waves in an unmagnetized collisionless pair-ion plasma with immobile positively charged dusts is studied for both large- and small-amplitude perturbations. Using a two-fluid model for pair-ions, it is shown that there appear two linear ion modes, namely the "fast" and "slow" waves in dusty pair-ion plasmas. The properties of these wave modes are studied with different mass $(m)$ and temperature $(T)$ ratios of negative to positive ions, as well as the effects of immobile charged dusts $(\\delta)$. For large-amplitude waves, the pseudopotential approach is performed, whereas the standard reductive perturbation technique (RPT) is used to study the small-amplitude Korteweg-de Vries (KdV) solitons. The profiles of the pseudopotential, the large amplitude solitons as well as the dynamical evolution of KdV solitons are numerically studied with the system parameters as above. It is found that the pair-ion plasmas with positively charged dusts support the propagation of solitary waves ...
Numerical Simulations of Radiatively-Driven Dusty Winds
Krumholz, Mark R
2013-01-01
Radiation pressure on dust grains may be an important mechanism in driving winds in a wide variety of astrophysical systems. However, the efficiency of the coupling between the radiation field and the dusty gas is poorly understood in environments characterized by high optical depths like those in ultra-luminous infrared galaxies (ULIRGs) and massive dense star clusters. We present a series of idealized numerical experiments, performed with the radiation-hydrodynamic code \\textsc{orion}, in which we study the dynamics of such winds and quantify their properties. We find that, after wind acceleration begins, radiation Rayleigh-Taylor instability forces the gas into a configuration that reduces the rate of momentum transfer from the radiation field to the gas by a factor ~ 10 - 100 compared to an estimate based on the optical depth at the base of the atmosphere; instead, the rate of momentum transfer from a driving radiation field of luminosity L to the gas is roughly L/c multiplied by half the optical depth at...
Flowing dusty plasma experiments: Generation of flow and measurement techniques
Jaiswal, S; Sen, A
2016-01-01
A variety of experimental techniques for the generation of subsonic/supersonic dust fluid flows and means of measuring such flow velocities are presented. The experiments have been carried out in a $\\Pi-$shaped Dusty Plasma Experimental (DPEx) device with micron size kaolin/Melamine Formaldehyde (MF) particles embedded in a background of Argon plasma created by a direct current (DC) glow discharge. A stationary dust cloud is formed over the cathode region by precisely balancing the pumping speed and gas flow rate. A flow of dust particles/fluid is generated by additional gas injection from a single or dual locations or by altering the dust confining potential. The flow velocity is then estimated by three different techniques, namely, by super Particle Identification (sPIT) code, Particle Image Velocimetry (PIV) analysis and the excitation of Dust Acoustic Waves (DAWs). The results obtained from these three different techniques along with their merits and demerits are discussed. An estimation of the neutral dr...
Radiative transfer modelling of parsec-scale dusty warped discs
Jud, H; Mould, J; Burtscher, L; Tristram, K R W
2016-01-01
Warped discs have been found on (sub-)parsec scale in some nearby Seyfert nuclei, identified by their maser emission. Using dust radiative transfer simulations we explore their observational signatures in the infrared in order to find out whether they can partly replace the molecular torus. Strong variations of the brightness distributions are found, depending on the orientation of the warp with respect to the line of sight. Whereas images at short wavelengths typically show a disc-like and a point source component, the warp itself only becomes visible at far-infrared wavelengths. A similar variety is visible in the shapes of the spectral energy distributions. Especially for close to edge-on views, the models show silicate feature strengths ranging from deep absorption to strong emission for variations of the lines of sight towards the warp. To test the applicability of our model, we use the case of the Circinus galaxy, where infrared interferometry has revealed a highly elongated emission component matching ...
Interaction of linear and nonlinear ion-sound waves with inclusions of dusty plasma
Energy Technology Data Exchange (ETDEWEB)
Grimalsky, V V [National Institute for Astrophysics, Optics, and Electronics (INAOE), Z.P. 72000, Puebla (Mexico); Koshevaya, S V [Autonomous University of Morelos (UAEM), FCQeI, CIICAp, Z.P. 62210, Cuernavaca, Mor. (Mexico); Enriquez, R Perez- [UNAM, Center of Geoscience, Juriquilla 1-742, Z.P. 76230, Que. (Mexico); Kotsarenko, A N [UNAM, Center of Geoscience, Juriquilla 1-742, Z.P. 76230, Que. (Mexico)
2006-09-15
Diverse phenomena exist in the ionosphere caused by the presence of dusty plasma objects. These have a bearing on problems of space communication and possibly on the Earth's weather, among others. Therefore, it is very important to study them so that many questions on the subject can be answered. In this paper, the interaction of plasma waves with these objects is studied and some instrumentation to measure such interactions is proposed. In particular, the interaction of ion-sound waves (ISW) by non-soliton and soliton pulses propagating in dusty plasma is investigated. It is shown that inclusions of dusty components of the ionosphere plasma behave as resonators for non-soliton pulses, so that ISW are excited. Korteveg-de Vries (KdV) solitons practically do not resonate with the inclusions of dusty plasma. Instead, the presence of dusty plasma inclusions can lead to the presence of transverse instabilities and the eventual destruction of the KdV solitons.
The bounded isometry conjecture for the Kodaira-Thurston manifold and 4-Torus
Han, Zhigang
2007-01-01
The purpose of this note is to study the bounded isometry conjecture proposed by Lalonde and Polterovich. In particular, we show that the conjecture holds for the Kodaira-Thurston manifold with the standard symplectic form and for the 4-torus with all linear symplectic forms.
Phases of three dimensional large N QCD on a continuum torus
Narayanan, R; Reynoso, F
2007-01-01
It is established by numerical means that continuum large N QCD defined on a three dimensional torus can exist in four different phases. They are (i) confined phase; (ii) deconfined phase; (iii) small box at zero temperature and (iv) small box at high temperatures.
THE FUNDAMENTAL GROUP OF THE AUTOMORPHISM GROUP OF A NONCOMMUTATIVE TORUS
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Assume that each completely irrational noncommutative torus is realized as an inductive limit of circle algebras, and that for a completely irrational noncommutative torus Aω of rank m there are a completely irrational noncommutative torus Aρ of rank m and a positive integer d such that tr(Aω) = 1/d. tr(Aρ). It is proved that the set of all C*-algebras of sections of locally trivial C*-algebra bundles over S2 with fibres Aω has a group structure, denoted by πs1(Aut(Aω)), which is isomorphic to Z. if d > 1 and {0} if d > 1. Let Bcd be a cd-homogeneous C*-algebra over S2 × T2 of which no non-trivial matrix algebra can be factored out. The spherical noncommutative torus Scdρ is defined by twisting C*(T2 × Zm-2) in Bcd C*(Zm-2) by a totally skew multiplier ρ on T2 × Zm-2. It is shown that Scdρ Mp∞ is isomorphic to C(S2) C*(T2 × Zm-2,ρ) Mcd(C) Mp∞ if and only if the set of prime factors of cd is a subset of the set of prime factors of p.
Design and simulation of a Torus topology for network on chip
Institute of Scientific and Technical Information of China (English)
Wu Chang; Li Yubai; Chai Song
2008-01-01
Aiming at the applications of NOC(network on chip)technology in rising scale and complexity on chip systems,a Torus structure and corresponding route algorithm for NOC is proposed.This Torus structure improves traditional Torus topology and redefines the denotations of the routers.Through redefining the router denotations and changing the origihal router locations,the Torns structure for NOC application is reconstructed.On the basis of this structure.a dead-lock and live-lock free route algorithm is designed according to dimension increase.System C is used to implement this structure and the route algorithm is simulated.In the four different traffic patterns.average,hotspot 13%,hotspot 67% and transpose,the average delay and normalization throughput of this Torus structure are evaluated.Then,the performance of delay and throughput between this Torns and Mesh structure is compared.The results indicate that this Torns structure is more suitable for NOC applications.
Condensates and instanton - torus knot duality. Hidden Physics at UV scale
Gorsky, A
2014-01-01
We establish the duality between the torus knot superpolynomials or the Poincare polynomials of the Khovanov homology and particular condensates in Omega-deformed 5D supersymmetric QED compactified on a circle with 5d Chern-Simons(CS) term. This is the generalization of the Witten's recipe of the evaluation of the knot polynomials via Wilson loops in 3d CS theory for case of the torus knots. It is explicitly shown that $n$-instanton contribution to the condensate of the massless flavor in the background of four-observable, which can be associated with some composite defect, exactly coincides with the superpolynomial of the T(n,nk+1) torus knot where k - is the level of CS term. In contrast to the previously known results, the particular torus knot corresponds not to the partition function of the gauge theory but to the particular instanton contribution and summation over the knots has to be performed in order to obtain the complete answer. The instantons are sitting almost at the top of each other and the phy...
Effect of plasma torus density variations on the morphology and brightness of the Io footprint
Payan, A. P.; Rajendar, A.; Paty, C. S.; Crary, F.
2014-05-01
We develop a 2-D-layered model of the Io plasma torus to study the apparent "shutoff" of the Io footprint in 2007, when it disappeared beneath a region of diffuse emissions, roughly coincident with a massive eruption of Tvashtar Paterae. First, we investigate the effects of Io's location in the plasma torus and validate our model results against Hubble UV observations of the Io footprint. We are able to qualitatively reproduce variations in the morphology of the footprint due to Io's changing latitudinal location with respect to the center of the plasma torus, capturing the bright leading spot and the dimmer tail. Then, we consider the effects of an increase in the local plasma density on the brightness and morphology of the Io footprint. Our results show a correlation between a local density increase in the plasma torus and the dimming of the Io footprint as observed in 2007. In particular, we find that a local density enhancement at Io of fivefold compared to the nominal value is sufficient to produce the observed shutoff of the footprint.
On the hyperbolic automorphisms of the 2-torus and their Markov partitions
Anosov, Dmitry V.; Alexey V. Klimenko; Kolutsky, Grisha
2008-01-01
In the paper we give an introduction to Anosov diffeomorphisms, ways to represent their chaotic properties and some historical remarks on this subject. A complete classification of hyperbolic linear automorphisms of 2-torus is presented. We introduce a notion of pre-Markov partition for such automorphisms and give their classification and an algorithm for their construction.
On the existence of star products on quotient spaces of linear Hamiltonian torus actions
DEFF Research Database (Denmark)
Herbig, Hans-Christian; Iyengar, Srikanth B.; Pflaum, Markus J.
2009-01-01
We discuss BFV deformation quantization (Bordemann et al. in A homological approach to singular reduction in deformation quantization, singularity theory, pp. 443–461. World Scientific, Hackensack, 2007) in the special case of a linear Hamiltonian torus action. In particular, we show that the Kos...
Computation-free presentation of the fundamental group of generic $(p,q)$-torus curves
Bartolo, Enrique Artal; Ortigas-Galindo, Jorge
2012-01-01
In this note, we present a new method for computing fundamental groups of curve complements using a variation of the Zariski-Van Kampen method on general ruled surfaces. As an application we give an alternative (computation-free) proof for the fundamental group of generic $(p,q)$-torus curves.
Topological Representations of $U_q(sl_2)$ on the Torus and the Mapping Class Group
Crivelli, M; Wieczerkowski, C; Felder, Giovanni
1993-01-01
We compute the mapping class group action on cycles on the configuration space of the torus with one puncture, with coefficients in a local system arising in conformal field theory. This action commutes with the topological action of the quantum group $U_q(sl_2)$, and is given in vertex form.
The spectrum of the torus profile to a geometric variational problem with long range interaction
Ren, Xiaofeng; Wei, Juncheng
2017-08-01
The profile problem for the Ohta-Kawasaki diblock copolymer theory is a geometric variational problem. The energy functional is defined on sets in R3 of prescribed volume and the energy of an admissible set is its perimeter plus a long range interaction term related to the Newtonian potential of the set. This problem admits a solution, called a torus profile, that is a set enclosed by an approximate torus of the major radius 1 and the minor radius q. The torus profile is both axially symmetric about the z axis and reflexively symmetric about the xy-plane. There is a way to set up the profile problem in a function space as a partial differential-integro equation. The linearized operator L of the problem at the torus profile is decomposed into a family of linear ordinary differential-integro operators Lm where the index m = 0 , 1 , 2 , … is called a mode. The spectrum of L is the union of the spectra of the Lm's. It is proved that for each m, when q is sufficiently small, Lm is positive definite. (0 is an eigenvalue for both L0 and L1, due to the translation and rotation invariance.) As q tends to 0, more and more Lm's become positive definite. However no matter how small q is, there is always a mode m of which Lm has a negative eigenvalue. This mode grows to infinity like q - 3 / 4 as q → 0.
Observations of the He+ pickup ion torus velocity distribution function with SOHO/CELIAS/CTOF
Taut, Andreas; Berger, Lars; Bochsler, Peter; Drews, Christian; Klecker, Berndt; Wimmer-Schweingruber, Robert F.
2016-03-01
Interstellar PickUp Ions (PUIs) are created from neutrals coming from the interstellar medium that get ionized inside the heliosphere. Once ionized, the freshly created ions are injected into the magnetized solar wind plasma with a highly anisotropic torus-shaped Velocity Distribution Function (VDF). It has been commonly assumed that wave-particle interactions rapidly destroy this torus by isotropizing the distribution in one hemisphere of velocity space. However, recent observations of a He+ torus distribution using PLASTIC on STEREO showed that the assumption of a rapid isotropization is oversimplified. The aim of this work is to complement these studies. Using He+ data from the Charge Time-Of-Flight (CTOF) sensor of the Charge, ELement, and Isotope Analysis System (CELIAS) on-board the SOlar and Heliospheric Observatory (SOHO) and magnetic field data from the Magnetic Field Investigation (MFI) magnetometer of the WIND spacecraft, we derive the projected 1-D VDF of He+ for different magnetic field configurations. Depending on the magnetic field direction, the initial torus VDF lies inside CTOF's aperture or not. By comparing the VDFs derived under different magnetic field directions with each other we reveal an anisotropic signature of the He+ VDF.
REPRESENTATIONS OF A CLASS OF ASSOCIATIVE ALGEBRAS ON THE QUANTUM TORUS OF RANK n
Institute of Scientific and Technical Information of China (English)
Lin Shangyuan; You Zhefeng
2008-01-01
In this paper,we present three types of representations over Anq defined based on the quantum torus of rank n,which are closely related to modules over some vertex algebras. The isomorphism classes among these modules are also determined.
One-to-one embedding between honeycomb mesh and Petersen-Torus networks.
Seo, Jung-Hyun; Sim, Hyun; Park, Dae-Heon; Park, Jang-Woo; Lee, Yang-Sun
2011-01-01
As wireless mobile telecommunication bases organize their structure using a honeycomb-mesh algorithm, there are many studies about parallel processing algorithms like the honeycomb mesh in Wireless Sensor Networks. This paper aims to study the Peterson-Torus graph algorithm in regard to the continuity with honeycomb-mesh algorithm in order to apply the algorithm to sensor networks. Once a new interconnection network is designed, parallel algorithms are developed with huge research costs to use such networks. If the old network is embedded in a newly designed network, a developed algorithm in the old network is reusable in a newly designed network. Petersen-Torus has been designed recently, and the honeycomb mesh has already been designed as a well-known interconnection network. In this paper, we propose a one-to-one embedding algorithm for the honeycomb mesh (HMn) in the Petersen-Torus PT(n,n), and prove that dilation of the algorithm is 5, congestion is 2, and expansion is 5/3. The proposed one-to-one embedding is applied so that processor throughput can be minimized when the honeycomb mesh algorithm runs in the Petersen-Torus.
Degree-Regular Triangulations of Torus and Klein Bottle-Erratum
Indian Academy of Sciences (India)
Basudeb Datta; Ashish Kumar Upadhyay
2005-08-01
A triangulation of a connected closed surface is called weakly regular if the action of its automorphism group on its vertices is transitive. A triangulation of a connected closed surface is called degree-regular if each of its vertices have the same degree. Clearly, a weakly regular triangulation is degree-regular. In [8], Lutz has classified all the weakly regular triangulations on at most 15 vertices. In [5], Datta and Nilakantan have classified all the degree-regular triangulations of closed surfaces on at most 11 vertices. In this article, we have proved that any degree-regular triangulation of the torus is weakly regular. We have shown that there exists an -vertex degree-regular triangulation of the Klein bottle if and only if is a composite number ≥ 9. We have constructed two distinct -vertex weakly regular triangulations of the torus for each ≥ 12 and a (4+2)-vertex weakly regular triangulation of the Klein bottle for each ≥ 2. For 12 ≤ ≤ 15, we have classified all the -vertex degree-regular triangulations of the torus and the Klein bottle. There are exactly 19 such triangulations, 12 of which are triangulations of the torus and remaining 7 are triangulations of the Klein bottle. Among the last 7, only one is weakly regular.
Huysmans, G. T. A.; Kerner, W.; Borba, D.; Holties, H. A.; Goedbloed, J. P.
1995-05-01
The active excitation of global Alfvén modes using the saddle coils in the Joint European Torus (JET) [Plasma Physics and Controlled Nuclear Fusion Research 1984, Proceedings of the 10th International Conference, London (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 11] as the external antenna, will provide information on the damping of global modes without the need to drive the modes unstable. For the modeling of the Alfvén mode excitation, the toroidal resistive magnetohydrodynamics (MHD) code CASTOR (Complex Alfvén Spectrum in TORoidal geometry) [18th EPS Conference On Controlled Fusion and Plasma Physics, Berlin, 1991, edited by P. Bachmann and D. C. Robinson (The European Physical Society, Petit-Lancy, 1991), Vol. 15, Part IV, p. 89] has been extended to calculate the response to an external antenna. The excitation of a high-performance, high beta JET discharge is studied numerically. In particular, the influence of a finite pressure is investigated. Weakly damped low-n global modes do exist in the gaps in the continuous spectrum at high beta. A pressure-driven global mode is found due to the interaction of Alfvén and slow modes. Its frequency scales solely with the plasma temperature, not like a pure Alfvén mode with a density and magnetic field.
DEFF Research Database (Denmark)
Levin, Marcus; Rojas, Elena; Vanhala, Esa
2015-01-01
Dustiness testing using a down-scaled EN15051 rotating drum was used to investigate the effects of storage conditions such as relative humidity and physical loading on the dustiness of five inorganic metal oxide nanostructured powder materials. The tests consisted of measurements of gravimetrical...
A dusty, normal galaxy in the epoch of reionization.
Watson, Darach; Christensen, Lise; Knudsen, Kirsten Kraiberg; Richard, Johan; Gallazzi, Anna; Michałowski, Michał Jerzy
2015-03-19
Candidates for the modest galaxies that formed most of the stars in the early Universe, at redshifts z > 7, have been found in large numbers with extremely deep restframe-ultraviolet imaging. But it has proved difficult for existing spectrographs to characterize them using their ultraviolet light. The detailed properties of these galaxies could be measured from dust and cool gas emission at far-infrared wavelengths if the galaxies have become sufficiently enriched in dust and metals. So far, however, the most distant galaxy discovered via its ultraviolet emission and subsequently detected in dust emission is only at z = 3.2 (ref. 5), and recent results have cast doubt on whether dust and molecules can be found in typical galaxies at z ≥ 7. Here we report thermal dust emission from an archetypal early Universe star-forming galaxy, A1689-zD1. We detect its stellar continuum in spectroscopy and determine its redshift to be z = 7.5 ± 0.2 from a spectroscopic detection of the Lyman-α break. A1689-zD1 is representative of the star-forming population during the epoch of reionization, with a total star-formation rate of about 12 solar masses per year. The galaxy is highly evolved: it has a large stellar mass and is heavily enriched in dust, with a dust-to-gas ratio close to that of the Milky Way. Dusty, evolved galaxies are thus present among the fainter star-forming population at z > 7.
Cleaning dusty gas wastes in the coking industry
Energy Technology Data Exchange (ETDEWEB)
Andreikov, E.I.; Anan' ina, L.P.; Zhilina, N.B.; Malysheva, N.V.; Zaidenberg, M.A.; Borodin, V.I.; Lisachenko, A.S.
1986-02-01
Gas wastes in coking industry contain coal and semicoke dust covered with tarry substances which prevent them being cleaned on the fixed bed of a catalyst. The paper examines whether it is possible to clean dusty gases of this type using a fluidized bed catalyst. Laboratory experiments using a continuous-flow reactor (diameter 0.02 m, height 0.2 m) and a gas supply rate of 9.6 x 10/sup -2/ m/sup 3//h are described. A mixture of aromatic hydrocarbons (concentration in gas phase - 3 g/m/sup 3/) was oxidized and the degree of conversion of the hydrocarbons was assessed by the amount of CO/sub 2/ found in the test reactor in comparison with that found in a control reactor with an AP-56 catalyst at 500 C; the CO/sub 2/ content was determined by chromatography. Dust content in the air at the fluidized bed was 6.5 g/m/sup 3/ and the amount of tar on the dust surfaces was 8%. Copper-vanadium oxide catalyst was found to work best at 450-550 C; higher temperatures reduce conversion rate (e.g. 3 hours at 720 C gave only 89% conversion). Volatile and tarry substances are absorbed, the amount of CO/sub 2/ in the gases increases and coal particles are converted to semicoke. The resulting dry dust is easier to collect in a dust collector. A pilot run at Khar'kov experimental coking plant resulted in 97.8% of hydrocarbons being romoved as well as 96% of CO. 3 references.
Nagao, T; Nozawa, T
2016-01-01
Many astronomical objects are surrounded by dusty environments. In such dusty objects, multiple scattering processes of photons by circumstellar (CS) dust grains can effectively alter extinction properties. In this paper, we systematically investigate effects of multiple scattering on extinction laws for steady-emission sources surrounded by the dusty CS medium, using a radiation transfer simulation based on the Monte Carlo technique. In particular, we focus on whether and how the extinction properties are affected by properties of CS dust grains, adopting various dust grain models. We {\\bf confirm} that behaviors of the (effective) extinction laws are highly dependent on the properties of CS grains. Especially, the total-to-selective extinction ratio $R_{V}$, which characterizes the extinction law, can be either increased or decreased, compared to the case without multiple scattering. We find that the criterion for this behavior is given by a ratio of albedos in the $B$ and $V$ bands. We also find that eithe...
Dusty plasma sheath-like structure in the region of lunar terminator
Energy Technology Data Exchange (ETDEWEB)
Popel, S. I.; Zelenyi, L. M. [Space Research Institute of the Russian Academy of Sciences, Moscow 117997, Russia and Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Region 141700 (Russian Federation); Atamaniuk, B. [Space Research Center of the Polish Academy of Sciences, Warsaw 00-716 (Poland)
2015-12-15
The main properties of the dusty plasma layer near the surface over the illuminated and dark parts of the Moon are described. They are used to realize dusty plasma behaviour and to determine electric fields over the terminator region. Possibility of the existence of a dusty plasma sheath-like structure in the region of lunar terminator is shown. The electric fields excited in the terminator region are demonstrated to be on the order of 300 V/m. These electric fields can result in rise of dust particles of the size of 2–3 μm up to an altitude of about 30 cm over the lunar surface that explains the effect of “horizon glow” observed at the terminator by Surveyor lunar lander.
Nonthermal Lorentzian wake-field effects on collision processes in complex dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Hong, Woo-Pyo [Department of Electronics Engineering, Catholic University of Daegu, Hayang 712-702 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590 (United States); Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)
2014-10-15
The influence of nonthermal Lorentzian wake-field on the electron-dust grain collision is investigated in complex dusty plasmas. The Eikonal method and the effective interaction potential are applied to obtain the Eikonal scattering phase shift, the differential Eikonal collision cross section, and the total Eikonal collision cross section as functions of the collision energy, the impact parameter, the Mach number, and the spectral index of Lorentzian plasma. It is found that the nonthermal effect enhances the Eikonal scattering phase shift and, however, suppresses the Eikonal collision cross section for the electron-dust grain in Lorentzian complex dusty plasmas. It is also found that the Eikonal scattering phase shift decreases with increasing Mach number and spectral index. In addition, the Eikonal collision cross section increases with an increase of the spectral index and Mach number in Lorentzian complex dusty plasmas.
Heat transfer to MHD oscillatory dusty fluid flow in a channel filled with a porous medium
Indian Academy of Sciences (India)
Om Prakash; O D Makinde; Devendra Kumar; Y K Dwivedi
2015-06-01
In this paper, we examine the combined effects of thermal radiation, buoyancy force and magnetic field on oscillatory flow of a conducting optically thin dusty fluid through a vertical channel filled with a saturated porous medium. The governing partial differential equations are obtained and solved analytically by variable separable method. Numerical results depicting the effects of various embedded parameters like radiation number, Hartmann number and Grashof number on dusty fluid velocity profiles, temperature profiles, Nusselt number and skin friction coefficient are presented graphically and discussed qualitatively.
Dust-cyclotron and dust-lower-hybrid modes in self-gravitating magnetized dusty plasmas
Indian Academy of Sciences (India)
A K Banerjee; M N Alam; A A Mamun
2003-07-01
Theoretical investigation has been made on two different ultra-low-frequency electrostatic modes, namely, dust-cyclotron mode and dust-lower-hybrid mode, propagating perpendicular to the external magnetic ﬁeld, in a self-gravitating magnetized two-ﬂuid dusty plasma system. It has been shown that the effect of the self-gravitational force, acting on both dust grains and ions, signiﬁcantly modiﬁes the dispersion properties of these two electrostatic modes. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring-systems and cometary tails, are brieﬂy mentioned.
Structure and phase transition of a two-dimensional dusty plasma
Institute of Scientific and Technical Information of China (English)
刘斌; 刘艳红; 陈雁萍; 杨思泽; 王龙
2003-01-01
The structure and phase transition of a two-dimensional (2D) dusty plasma have been investigated in detail by molecular dynamics simulation. Pair correlation function, static structure factor, mean square displacement, and bond angle correlation function have been calculated to characterize the structural properties. The variation of internal energy, shear modulus, particle trajectories and structural properties with temperature has been monitored to study the phase transition of the 2D dusty plasma system. The simulation results are in favour of a two-step continuous transition for this kind of plasma.
Thermal Marangoni Convection of Two-phase Dusty Fluid Flow along a Vertical Wavy Surface
Directory of Open Access Journals (Sweden)
S. Siddiqa
2017-01-01
Full Text Available The paper considers the influence of thermal Marangoni convection on boundary layer flow of two-phase dusty fluid along a vertical wavy surface. The dimensionless boundary layer equations for two-phase problem are reduced to a convenient form by primitive variable transformations (PVF and then integrated numerically by employing the implicit finite difference method along with the Thomas Algorithm. The effect of thermal Marangoni convection, dusty water and sinusoidal waveform are discussed in detail in terms of local heat transfer rate, skin friction coefficient, velocity and temperature distributions. This investigation reveals the fact that the water-particle mixture reduces the rate of heat transfer, significantly.
Discovery of a warm, dusty giant planet around HIP 65426
Chauvin, G.; Desidera, S.; Lagrange, A.-M.; Vigan, A.; Gratton, R.; Langlois, M.; Bonnefoy, M.; Beuzit, J.-L.; Feldt, M.; Mouillet, D.; Meyer, M.; Cheetham, A.; Biller, B.; Boccaletti, A.; D'Orazi, V.; Galicher, R.; Hagelberg, J.; Maire, A.-L.; Mesa, D.; Olofsson, J.; Samland, M.; Schmidt, T. O. B.; Sissa, E.; Bonavita, M.; Charnay, B.; Cudel, M.; Daemgen, S.; Delorme, P.; Janin-Potiron, P.; Janson, M.; Keppler, M.; Le Coroller, H.; Ligi, R.; Marleau, G. D.; Messina, S.; Mollière, P.; Mordasini, C.; Müller, A.; Peretti, S.; Perrot, C.; Rodet, L.; Rouan, D.; Zurlo, A.; Dominik, C.; Henning, T.; Menard, F.; Schmid, H.-M.; Turatto, M.; Udry, S.; Vakili, F.; Abe, L.; Antichi, J.; Baruffolo, A.; Baudoz, P.; Baudrand, J.; Blanchard, P.; Bazzon, A.; Buey, T.; Carbillet, M.; Carle, M.; Charton, J.; Cascone, E.; Claudi, R.; Costille, A.; Deboulbe, A.; De Caprio, V.; Dohlen, K.; Fantinel, D.; Feautrier, P.; Fusco, T.; Gigan, P.; Giro, E.; Gisler, D.; Gluck, L.; Hubin, N.; Hugot, E.; Jaquet, M.; Kasper, M.; Madec, F.; Magnard, Y.; Martinez, P.; Maurel, D.; Le Mignant, D.; Möller-Nilsson, O.; Llored, M.; Moulin, T.; Origné, A.; Pavlov, A.; Perret, D.; Petit, C.; Pragt, J.; Puget, P.; Rabou, P.; Ramos, J.; Rigal, R.; Rochat, S.; Roelfsema, R.; Rousset, G.; Roux, A.; Salasnich, B.; Sauvage, J.-F.; Sevin, A.; Soenke, C.; Stadler, E.; Suarez, M.; Weber, L.; Wildi, F.; Antoniucci, S.; Augereau, J.-C.; Baudino, J.-L.; Brandner, W.; Engler, N.; Girard, J.; Gry, C.; Kral, Q.; Kopytova, T.; Lagadec, E.; Milli, J.; Moutou, C.; Schlieder, J.; Szulágyi, J.; Thalmann, C.; Wahhaj, Z.
2017-09-01
Aims: The SHINE program is a high-contrast near-infrared survey of 600 young, nearby stars aimed at searching for and characterizing new planetary systems using VLT/SPHERE's unprecedented high-contrast and high-angular-resolution imaging capabilities. It is also intended to place statistical constraints on the rate, mass and orbital distributions of the giant planet population at large orbits as a function of the stellar host mass and age to test planet-formation theories. Methods: We used the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-contrast coronagraphic differential near-infrared images and spectra of the young A2 star HIP 65426. It is a member of the 17 Myr old Lower Centaurus-Crux association. Results: At a separation of 830 mas (92 au projected) from the star, we detect a faint red companion. Multi-epoch observations confirm that it shares common proper motion with HIP 65426. Spectro-photometric measurements extracted with IFS and IRDIS between 0.95 and 2.2 μm indicate a warm, dusty atmosphere characteristic of young low-surface-gravity L5-L7 dwarfs. Hot-start evolutionary models predict a luminosity consistent with a 6-12 MJup, Teff = 1300-1600 K and R = 1.5 ± 0.1 RJup giant planet. Finally, the comparison with Exo-REM and PHOENIX BT-Settl synthetic atmosphere models gives consistent effective temperatures but with slightly higher surface gravity solutions of log (g) = 4.0-5.0 with smaller radii (1.0-1.3 RJup). Conclusions: Given its physical and spectral properties, HIP 65426 b occupies a rather unique placement in terms of age, mass, and spectral-type among the currently known imaged planets. It represents a particularly interesting case to study the presence of clouds as a function of particle size, composition, and location in the atmosphere, to search for signatures of non-equilibrium chemistry, and finally to test the theory of planet formation and evolution. Based on observations collected at La Silla
Watching a 'New Star' Make the Universe Dusty
2008-07-01
Using ESO's Very Large Telescope Interferometer, and its remarkable acuity, astronomers were able for the first time to witness the appearance of a shell of dusty gas around a star that had just erupted, and follow its evolution for more than 100 days. This provides the astronomers with a new way to estimate the distance of this object and obtain invaluable information on the operating mode of stellar vampires, dense stars that suck material from a companion. Uncovering the disc ESO PR Photo 22/08 Dust shells around a nova Although novae were first thought to be new stars appearing in the sky, hence their Latin name, they are now understood as signaling the brightening of a small, dense star. Novae occur in double star systems comprising a white dwarf - the end product of a solar-like star - and, generally, a low-mass normal star - a red dwarf. The two stars are so close together that the red dwarf cannot hold itself together and loses mass to its companion. Occasionally, the shell of matter that has fallen onto the ingesting star becomes unstable, leading to a thermonuclear explosion which makes the system brighter. Nova Scorpii 2007a (or V1280 Scorpii), was discovered by Japanese amateur astronomers on 4 February 2007 towards the constellation Scorpius ("the Scorpion"). For a few days, it became brighter and brighter, reaching its maximum on 17 February, to become one of the brightest novae of the last 35 years. At that time, it was easily visible with the unaided eye. Eleven days after reaching its maximum, astronomers witnessed the formation of dust around the object. Dust was present for more than 200 days, as the nova only slowly emerged from the smoke between October and November 2007. During these 200 days, the erupting source was screened out efficiently, becoming more than 10,000 times dimmer in the visual. An unprecedented high spatial resolution monitoring of the dust formation event was carried out with the Very Large Telescope Interferometer (VLTI
Large-amplitude double layers in a dusty plasma with an arbitrary streaming ion beam
Indian Academy of Sciences (India)
Brindaban Das; Debkumar Ghosh; Prasanta Chatterjee
2010-06-01
Formation of large-amplitude double layers in a dusty plasma whose constituents are electrons, ions, warm dust grains and positive ion beam are studied using Sagdeev’s pseudopotential technique. Existence of double layers is investigated. It is found that both the temperature of dust particles and ion beam temperature play significant roles in determining the region of the existence of double layers.
Nagao, Takashi; Maeda, Keiichi; Nozawa, Takaya
2016-06-01
Many astronomical objects are surrounded by dusty environments. In such dusty objects, multiple scattering processes of photons by circumstellar (CS) dust grains can effectively alter extinction properties. In this paper, we systematically investigate the effects of multiple scattering on extinction laws for steady-emission sources surrounded by the dusty CS medium using a radiation transfer simulation based on the Monte Carlo technique. In particular, we focus on whether and how the extinction properties are affected by properties of CS dust grains by adopting various dust grain models. We confirm that behaviors of the (effective) extinction laws are highly dependent on the properties of CS grains, especially the total-to-selective extinction ratio R V , which characterizes the extinction law and can be either increased or decreased and compared with the case without multiple scattering. We find that the criterion for this behavior is given by a ratio of albedos in the B and V bands. We also find that either small silicate grains or polycyclic aromatic hydrocarbons are necessary for realizing a low value of R V as often measured toward SNe Ia if the multiple scattering by CS dust is responsible for their non-standard extinction laws. Using the derived relations between the properties of dust grains and the resulting effective extinction laws, we propose that the extinction laws toward dusty objects could be used to constrain the properties of dust grains in CS environments.
Effect of viscosity on dust–ion acoustic shock wave in dusty plasma with negative ions
Energy Technology Data Exchange (ETDEWEB)
Adhikary, Nirab C., E-mail: nirab_iasst@yahoo.co.in [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati 781035, Assam (India)
2012-03-26
The properties of dust–ion acoustic (DIA) shock wave in a dusty plasma containing positive and negative ions is investigated. The reductive perturbation method has been used to derive the Korteweg–de Vries–Burgers equation for dust acoustic shock waves in a homogeneous, unmagnetized and collisionless plasma whose constituents are Boltzmann distributed electrons, singly charged positive ions, singly charged negative ions and cold static dust particles. The KdV–Burgers equation is derived and its stationary analytical solution is numerically analyzed where the effect of viscosity on the DIA shock wave propagation is taken into account. It is found that the viscosity in the dusty plasma plays as a key role in dissipation for the propagation of DIA shock. -- Highlights: ► Dust–ion acoustic shock wave propagation is studied in multi-component dusty plasma. ► KdV–Burgers equation is derived and its stationary solution is numerically analyzed. ► Viscosity in dusty plasma plays as a key role in dissipation of DIA shock wave.
The connection between AGN-driven dusty outflows and the surrounding environment
Ishibashi, W.; Fabian, A. C.
2016-04-01
Significant reservoirs of cool gas are observed in the circumgalactic medium (CGM) surrounding galaxies. The CGM is also found to contain substantial amounts of metals and dust, which require some transport mechanism. We consider AGN (active galactic nucleus) feedback-driven outflows based on radiation pressure on dust. Dusty gas is ejected when the central luminosity exceeds the effective Eddington luminosity for dust. We obtain that a higher dust-to-gas ratio leads to a lower critical luminosity, implying that the more dusty gas is more easily expelled. Dusty outflows can reach large radii with a range of velocities (depending on the outflowing shell configuration and the ambient density distribution) and may account for the observed CGM gas. In our picture, dust is required in order to drive AGN feedback, and the preferential expulsion of dusty gas in the outflows may naturally explain the presence of dust in the CGM. On the other hand, the most powerful AGN outflow events can potentially drive gas out of the local galaxy group. We further discuss the effects of radiation pressure of the central AGN on satellite galaxies. AGN radiative feedback may therefore have a significant impact on the evolution of the whole surrounding environment.
Final Progress Report for Ionospheric Dusty Plasma In the Laboratory [Smokey Plasma
Energy Technology Data Exchange (ETDEWEB)
Robertson, Scott [Univ. of Colorado, Boulder, CO (United States)
2010-07-31
“Ionospheric Dusty Plasma in the Laboratory” is a research project with the purpose of finding and reproducing the characteristics of plasma in the polar mesosphere that is unusually cold (down to 140 K) and contains nanometer-sized dust particles. This final progress report summarizes results from four years of effort that include a final year with a no-cost extension.
Dust acoustic and drift waves in a non-Maxwellian dusty plasma with dust charge fluctuation
Zakir, U.; Haque, Q.; Imtiaz, N.; Qamar, A.
2015-12-01
> ) on the wave dispersion and instability are presented. It is found that the presence of the non-thermal electron and ion populations reduce the growth rate of the instability which arises due to the dust charging effect. In addition, the nonlinear vortex solutions are also obtained. For illustration, the results are analysed by using the dusty plasma parameters of Saturn's magnetosphere.
Nonlinear acoustic waves in a collisional self-gravitating dusty plasma
Institute of Scientific and Technical Information of China (English)
Guo Zhi-Rong; Yang Zeng-Qiang; Yin Bao-Xiang; Sun Mao-Zhu
2010-01-01
Using the reductive perturbation method,we investigate the small amplitude nonlinear acoustic wave in a collisional self-gravitating dusty plasma.The result shows that the small amplitude dust acoustic wave can be expressed by a modified Korteweg-de Vries equation,and the nonlinear wave is instable because of the collisions between the neutral gas molecules and the charged particles.
The connection between AGN-driven dusty outflows and the surrounding environment
Ishibashi, W
2016-01-01
Significant reservoirs of cool gas are observed in the circumgalactic medium (CGM) surrounding galaxies. The CGM is also found to contain substantial amounts of metals and dust, which require some transport mechanism. We consider AGN (active galactic nucleus) feedback-driven outflows based on radiation pressure on dust. Dusty gas is ejected when the central luminosity exceeds the effective Eddington luminosity for dust. We obtain that a higher dust-to-gas ratio leads to a lower critical luminosity, implying that the more dusty gas is more easily expelled. Dusty outflows can reach large radii with a range of velocities (depending on the outflowing shell configuration and the ambient density distribution) and may account for the observed CGM gas. In our picture, dust is required in order to drive AGN feedback, and the preferential expulsion of dusty gas in the outflows may naturally explain the presence of dust in the CGM. On the other hand, the most powerful AGN outflow events can potentially drive gas out of ...
Flow of a Dusty Gas with Suspended Particles in a Rotating Frame of Reference
Directory of Open Access Journals (Sweden)
P. Mitra
1981-01-01
Full Text Available The solution is given for the problem on the motion of a dusty gas under a rotating system of co-ordinates. The gas containing a uniform distribution of dust particles, occupies the infinite space above a rigid plane boundary. The motion of the dusty gas is induced by the motion of the plate moving with a velocity which decreases exponentially with time in a rotating frame of reference such that the plate and the gas are in a state of rigid body rotation about an axis normal to the plate. The velocity fields for the dusty gas, and the dust particles along and normal to the direction of motion of the plate are obtained in closed forms. Finally, some velocity distributions are calculated with particular reference to the effect of rotation at different times, and it is found that with the increase of the value of the rotation parameter omega, the velocity of the dusty gas along the direction of motion of the plate gradually increases while the velocity of the dust particle along the same direction gradually decreases.
Novel routes to chaos through torus breakdown in non-invertible maps
DEFF Research Database (Denmark)
Zhusubaliyev, Zhanybai; Mosekilde, Erik
2009-01-01
The paper describes a number of new scenarios for the transition to chaos through the formation and destruction of multilayered tori in non-invertible maps. By means of detailed, numerically calculated phase portraits we first describe how three- and five-layered tori arise through period......-doubling and/or pitchfork bifurcations of the saddle cycle on an ordinary resonance torus. We then describe several different mechanisms for the destruction of five-layered tori in a system of two linearly coupled logistic maps. One of these scenarios involves the destruction of the two intermediate layers...... of the five-layered torus through the transformation of two unstable node cycles into unstable focus cycles, followed by a saddle-node bifurcation that destroys the middle layer and a pair of simultaneous homoclinic bifurcations that produce two invariant closed curves with quasiperiodic dynamics along...
Torus breakdown in the symmetry-reduced state space of the Kuramoto-Sivashinsky system
Budanur, Nazmi Burak
2015-01-01
Systems such as fluid flows in channels and pipes or the complex Ginzburg-Landau system, defined over periodic domains, exhibit both continuous symmetries, translational and rotational, as well as discrete symmetries under spatial reflections or complex conjugation. The simplest, and very common symmetry of this type is the equivariance of the defining equations under the orthogonal group O(2). We formulate a novel symmetry-reduction scheme for such systems by combining the method of slices with invariant polynomial methods, and show how it works by applying it to the Kuramoto-Sivashinsky system in one spatial dimension. As an example, we track a relative periodic orbit through a sequence of bifurcation to the onset of chaos. Within the symmetry-reduced state space we are able to compute and visualize the unstable manifolds of relative periodic orbits, their torus bifurcations, a transition to chaos via torus breakdown, and heteroclinic connections between various relative periodic orbits. It would be very ha...
Research on Next-Generation Scalable Routers Implemented with H-Torus Topology
Institute of Scientific and Technical Information of China (English)
You-Jian Zhao; Zu-Hui Yue; Jian-Ping Wu
2008-01-01
The exponential growth of user traffic has been driving routers to run at higher capacity. In a traditional router, the centralized switching fabric is becoming the bottleneck for its limited number of ports and complicated scheduling algorithms. Direct networks, such as 3-D Torus topology, have been successfully applied to the design of scalable routers.They show good scalability and fault tolerance. Unfortunately, its scalability is limited in practice. In this paper, we introduce another type of direct network, called H-Torus. This network shows excellent topological properties. On its basis,the designs of line card and routing algorithms are introduced. Extensive simulations show that the routing algorithm is very important in such a system and results in low latency with high throughpnt.
Energy Technology Data Exchange (ETDEWEB)
Smith, D. R.; Fonck, R. J.; McKee, G. R.; Thompson, D. S. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Bell, R. E.; Diallo, A.; Guttenfelder, W.; Kaye, S. M.; LeBlanc, B. P.; Podesta, M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2013-05-15
The spherical torus edge region is among the most challenging regimes for plasma turbulence simulations. Here, we measure the spatial and temporal properties of ion-scale turbulence in the steep gradient region of H-mode pedestals during edge localized mode-free, MHD quiescent periods in the National Spherical Torus Experiment. Poloidal correlation lengths are about 10 ρ{sub i}, and decorrelation times are about 5 a/c{sub s}. Next, we introduce a model aggregation technique to identify parametric dependencies among turbulence quantities and transport-relevant plasma parameters. The parametric dependencies show the most agreement with transport driven by trapped-electron mode, kinetic ballooning mode, and microtearing mode turbulence, and the least agreement with ion temperature gradient turbulence. In addition, the parametric dependencies are consistent with turbulence regulation by flow shear and the empirical relationship between wider pedestals and larger turbulent structures.
Stability of small-amplitude torus knot solutions of the localized induction approximation
Calini, Annalisa; Ivey, Thomas
2011-08-01
We study the linear stability of small-amplitude torus knot solutions of the localized induction approximation equation for the motion of a thin vortex filament in an ideal fluid. Such solutions can be constructed analytically through the connection with the focusing nonlinear Schrödinger equation using the method of isoperiodic deformations. We show that these (p, q) torus knots are generically linearly unstable for p q, in contrast with an earlier linear stability study by Ricca (1993 Chaos 3 83-95 1995 Chaos 5 346; 1995 Small-scale Structures in Three-dimensional Hydro and Magneto-dynamics Turbulence (Lecture Notes in Physics vol 462) (Berlin: Springer)). We also provide an interpretation of the original perturbative calculation in Ricca (1995), and an explanation of the numerical experiments performed by Ricca et al (1999 J. Fluid Mech. 391 29-44), in light of our results.
Bilateral Mandibular Torus and an Ankylosed Third Molar: A Case Report
Directory of Open Access Journals (Sweden)
Hasan Onur Şimşek
2016-04-01
Full Text Available Environmental factors, genetic heritage, increased biting function and nutrition are some of the reason for intraoral exostosis to get developed. Torus mandibularis is one of the types of exostosis in the oral region, which is unilaterally or bilaterally located in the lingual aspect of the body of the mandible above the mylohyoid line. There is usually no need for biopsy for the diagnosis of tori. In symptomatic cases, excision is the treatment of choice. In this paper, a 65-year-old man with a wide bilateral mandibular torus and an ankylosed mandibular right third molar tooth with mucosal retention is presented and general information was given about tori. In relation with this case, it was thought that dental ankylosis and tori may occur together because of similar etiological factors.
Superpolynomials for torus knots from evolution induced by cut-and-join operators
Dunin-Barkowski, P.; Mironov, A.; Morozov, A.; Sleptsov, A.; Smirnov, A.
2013-03-01
The colored HOMFLY polynomials, which describe Wilson loop averages in Chern-Simons theory, possess an especially simple representation for torus knots, which begins from quantum R-matrix and ends up with a trivially-looking split W representation familiar from character calculus applications to matrix models and Hurwitz theory. Substitution of MacDonald polynomials for characters in these formulas provides a very simple description of "superpolynomials", much simpler than the recently studied alternative which deforms relation to the WZNW theory and explicitly involves the Littlewood-Richardson coefficients. A lot of explicit expressions are presented for different representations (Young diagrams), many of them new. In particular, we provide the superpolynomial {P}_{{[ 1 ]}}^{{[ {m,km± 1} ]}} for arbitrary m and k. The procedure is not restricted to the fundamental (all antisymmetric) representations and the torus knots.
Spectrum in the presence of brane-localized mass on torus extra dimensions
Sakamura, Yutaka
2016-01-01
The lightest mass eigenvalue of a six-dimensional theory compactified on a torus is numerically evaluated in the presence of the brane-localized mass term. The dependence on the cutoff scale $\\Lambda$ is non-negligible even when $\\Lambda$ is two orders of magnitude above the compactification scale, which indicates that the mass eigenvalue is sensitive to the size of the brane, in contrast to five-dimensional theories. We obtain an approximate expression of the lightest mass in the thin brane limit, which well fits the numerical calculations, and clarifies its dependence on the torus moduli parameter $\\tau$. We found that the lightest mass is typically much lighter than the compactification scale by an order of magnitude even in the limit of a large brane mass.
Magnetized plasma flow injection into tokamak and high-beta compact torus plasmas
Matsunaga, Hiroyuki; Komoriya, Yuuki; Tazawa, Hiroyasu; Asai, Tomohiko; Takahashi, Tsutomu; Steinhauer, Loren; Itagaki, Hirotomo; Onchi, Takumi; Hirose, Akira
2010-11-01
As an application of a magnetized coaxial plasma gun (MCPG), magnetic helicity injection via injection of a highly elongated compact torus (magnetized plasma flow: MPF) has been conducted on both tokamak and field-reversed configuration (FRC) plasmas. The injected plasmoid has significant amounts of helicity and particle contents and has been proposed as a fueling and a current drive method for various torus systems. In the FRC, MPF is expected to generate partially spherical tokamak like FRC equilibrium by injecting a significant amount of magnetic helicity. As a circumstantial evidence of the modified equilibrium, suppressed rotational instability with toroidal mode number n = 2. MPF injection experiments have also been applied to the STOR-M tokamak as a start-up and current drive method. Differences in the responses of targets especially relation with beta value and the self-organization feature will be studied.
Quintilio, R.; Viegas, S. M.
1997-01-01
Theoretical emission-line profiles are obtained for active galactic nuclei (AGNs) taking into account the presence of an obscuring torus around the central energy source. For the sake of simplicity, the torus is represented by a cylindrical shell characterized by the inner and outer radius and the opening angle. In this paper we discuss the results with angle of sight equal to 0, i.e., for a face-on torus. Different line profiles are obtained following the torus parameters. The line profiles may show more than one peak and bumps, depending on the torus dimensions. The main parameter determining the number of peaks or bumps is the opening angle. Thus, the observed line shape may be a good indicator of the torus characteristics. As an example, the fit to the observed [O III] λ5007 emission line of NGC 4151 is presented. The model reproduces the FWHM and the asymmetrical bumps observed. Partially supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) under Grant 92/4335-9.
Hierarchical Cantor set in the large scale structure with torus geometry
Energy Technology Data Exchange (ETDEWEB)
Murdzek, R. [Physics Department, ' Al. I. Cuza' University, Blvd. Carol I, Nr. 11, Iassy 700506 (Romania)], E-mail: rmurdzek@yahoo.com
2008-12-15
The formation of large scale structures is considered within a model with string on toroidal space-time. Firstly, the space-time geometry is presented. In this geometry, the Universe is represented by a string describing a torus surface. Thereafter, the large scale structure of the Universe is derived from the string oscillations. The results are in agreement with the cellular structure of the large scale distribution and with the theory of a Cantorian space-time.
THE SCENERY FLOW FOR GEOMETRIC STRUCTURES ON THE TORUS: THE LINEAR SETTING
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The authors define the scenery flow of the torus. The flow space is the union of all flat 2- dimensional tori of area 1 with a marked direction (or equivalently, the union of all tori with a quadratic differential of norm 1). This is a 5-dimensional space, and the flow acts by following individual points under an extremal deformation of the quadratic differential. The authors define associated horocycle and translation flows; the latter preserve each torus and are the horizontal and vertical flows of the corresponding quadratic differential. The scenery flow projects to the geodesic flow on the modular surface, and admits, for each orientation preserving hyperbolic toral automorphism, an invariant 3-dimensional subset on which it is the suspension flow of that map. The authors first give a simple algebraic definition in terms of the group of affine maps of the plane, and prove that the flow is Anosov. They give an explicit formula for the first-return map of the flow on convenient cross-sections. Then, in the main part of the paper, the authors give several different models for the flow and its cross-sections, in terms of: ● stacking and rescaling periodic tilings of the plane; ● symbolic dynamics: the natural extension of the recoding of Sturmian sequences, or the S-adic system generated by two substitutions; ● zooming and subdividing quasi-periodic tilings of the real line, or aperiodic quasicrystals of minimal complexity; ● the natural extension of two-dimensional continued fractions; ● induction on exchanges of three intervals; ● rescaling on pairs of transverse measure foliations on the torus, or the Teichmiiller flow on the twice-punctured torus.
DEFF Research Database (Denmark)
Gravesen, Jens; Willatzen, Morten; Voon, L.C. Lew Yan
2005-01-01
The theory of a quantum-mechanical particle confined to a surface of revolution is described using differential geometry methods including the derivation of a general set of three ordinary differential equations in curved coordinates. The problem is shown to be completely separable with the prese...... hard-wall boundary conditions. Two case studies of recent experimental interest. the nanocone and torus-shaped nanoring structures. are analyzed in terms of eigenstates, energies. and symmetry characteristics based on the theory presented....
Algebraic K-theory and derived equivalences suggested by T-duality for torus orientifolds
Rosenberg, Jonathan
2016-01-01
We show that certain isomorphisms of (twisted) KR-groups that underlie T-dualities of torus orientifold string theories have purely algebraic analogues in terms of algebraic K-theory of real varieties and equivalences of derived categories of (twisted) coherent sheaves. The most interesting conclusion is a kind of Mukai duality in which the "dual abelian variety" to a smooth projective genus-1 curve over R with no real points is (mildly) noncommutative.
Indecomposable representations of the Lie algebra of derivations for d-torus
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Let DerA be the Lie algebra of derivations of the d-torus A = C[t1± 1, . . . , td±1]. By applying Shen-Larsson’s functors we get a class of indecomposable DerA-modules from finite-dimensional indecomposable gld-modules. We also give a complete description of the submodules of these indecomposable DerA-modules. Our results generalize those obtained by Rao.
Quantization of a class of piecewise affine transformations on the torus
De Bièvre, S; De Bievre, S; Giachetti, R
1995-01-01
We present a unified framework for the quantization of a family of discrete dynamical systems of varying degrees of ``chaoticity". The systems to be quantized are piecewise affine maps on the two-torus, viewed as phase space, and include the automorphisms, translations and skew translations. We then treat some discontinuous transformations such as the Baker map and the sawtooth-like maps. Our approach extends some ideas from geometric quantization and it is both conceptually and calculationally simple.
Creation of a dense torus in the coalescence of a black hole with a neutron star
1999-01-01
We used a newtonian SPH (smooth-particle hydrodynamics) code to follow the final stages of evolution of a coalescing binary system of a neutron star and a black hole. We find that the outcome of the "merger" is very sensitive to the equation of state describing the neutron star. A neutron star with a soft equation of state (polytrope with index Gamma=5/3) is completely disrupted, and a fairly large and long-lived accretion torus is formed.
Quantum revivals in two degrees of freedom integrable systems : the torus case
Lablée, Olivier
2010-01-01
The paper deals with the semi-classical behaviour of quantum dynamics for a semi-classical completely integrable system with two degrees of freedom near Liouville regular torus. The phenomomenon of wave packet revivals is demonstrated in this article. The framework of this paper is semi-classical analysis (limit :). For the proofs we use standard tools of real analysis, Fourier analysis and basic analytic number theory.
A mid-infrared statistical investigation of clumpy torus model predictions
García-González, J.; Alonso-Herrero, A.; Hönig, S. F.; Hernán-Caballero, A.; Ramos Almeida, C.; Levenson, N. A.; Roche, P. F.; González-Martín, O.; Packham, C.; Kishimoto, M.
2017-09-01
We present new calculations of the Clumpy AGN Tori in a 3D geometry (CAT3D) clumpy torus models, which now include a more physical dust sublimation model as well as active galactic nucleus (AGN) anisotropic emission. These new models allow graphite grains to persist at temperatures higher than the silicate dust sublimation temperature. This produces stronger near-infrared emission and bluer mid-infrared (MIR) spectral slopes. We make a statistical comparison of the CAT3D model MIR predictions with a compilation of sub-arcsecond resolution ground-based MIR spectroscopy of 52 nearby Seyfert galaxies (median distance of 36 Mpc) and 10 quasars. We focus on the AGN MIR spectral index αMIR and the strength of the 9.7 μm silicate feature SSil. As with other clumpy torus models, the new CAT3D models do not reproduce the Seyfert galaxies with deep silicate absorption (SSil low photon escape probabilities, while the quasars and the Seyfert 1-1.5 require generally models with higher photon escape probabilities. Quasars and Seyfert 1-1.5 tend to show steeper radial cloud distributions and fewer clouds along an equatorial line of sight than Seyfert 2. Introducing AGN anisotropic emission besides the more physical dust sublimation models alleviates the problem of requiring inverted radial cloud distributions (i.e. more clouds towards the outer parts of the torus) to explain the MIR spectral indices of type 2 Seyferts.
Condensates and instanton – torus knot duality. Hidden Physics at UV scale
Directory of Open Access Journals (Sweden)
A. Gorsky
2015-11-01
Full Text Available We establish the duality between the torus knot superpolynomials or the Poincaré polynomials of the Khovanov homology and particular condensates in Ω-deformed 5D supersymmetric QED compactified on a circle with 5d Chern–Simons (CS term. It is explicitly shown that n-instanton contribution to the condensate of the massless flavor in the background of four-observable exactly coincides with the superpolynomial of the T(n,nk+1 torus knot where k is the level of CS term. In contrast to the previously known results, the particular torus knot corresponds not to the partition function of the gauge theory but to the particular instanton contribution and summation over the knots has to be performed in order to obtain the complete answer. The instantons are sitting almost at the top of each other and the physics of the “fat point” where the UV degrees of freedom are slaved with point-like instantons turns out to be quite rich. Also we see knot polynomials in the quantum mechanics on the instanton moduli space. We consider the different limits of this correspondence focusing at their physical interpretation and compare the algebraic structures at the both sides of the correspondence. Using the AGT correspondence, we establish a connection between superpolynomials for unknots and q-deformed DOZZ factors.
Advanced tokamak reactors based on the spherical torus (ATR/ST). Preliminary design considerations
Energy Technology Data Exchange (ETDEWEB)
Miller, R.L.; Krakowski, R.A.; Bathke, C.G.; Copenhaver, C.; Schnurr, N.M.; Engelhardt, A.G.; Seed, T.J.; Zubrin, R.M.
1986-06-01
Preliminary design results relating to an advanced magnetic fusion reactor concept based on the high-beta, low-aspect-ratio, spherical-torus tokamak are summarized. The concept includes resistive (demountable) toroidal-field coils, magnetic-divertor impurity control, oscillating-field current drive, and a flowing liquid-metal breeding blanket. Results of parametric tradeoff studies, plasma engineering modeling, fusion-power-core mechanical design, neutronics analyses, and blanket thermalhydraulics studies are described. The approach, models, and interim results described here provide a basis for a more detailed design. Key issues quantified for the spherical-torus reactor center on the need for an efficient drive for this high-current (approx.40 MA) device as well as the economic desirability to increase the net electrical power from the nominal 500-MWe(net) value adopted for the baseline system. Although a direct extension of present tokamak scaling, the stablity and transport of this high-beta (approx.0.3) plasma is a key unknown that is resoluble only by experiment. The spherical torus generally provides a route to improved tokamak reactors as measured by considerably simplified coil technology in a configuration that allows a realistic magnetic divertor design, both leading to increased mass power density and reduced cost.
Herschel-ATLAS: Dusty early-type galaxies
Rowlands, K.; Dunne, L.; Maddox, S.
2015-03-01
Early-type galaxies (ETGs) are thought to be devoid of dust and star-formation, having formed most of their stars at early epochs. We present the detection of the dustiest ETGs in a large-area blind submillimetre survey with Herschel (H-ATLAS, Eales et al. 2010), where the lack of pre-selection in other bands makes it the first unbiased survey for cold dust in ETGs. The parent sample of 1087 H-ATLAS galaxies in this study have a >= 5σ detection at 250μm, a reliable optical counterpart to the submillimetre source (Smith et al. 2011) and a spectroscopic redshift from the GAMA survey (Driver et al. 2011). Additionally, we construct a control sample of 1052 optically selected galaxies undetected at 250μm and matched in stellar mass to the H-ATLAS parent sample to eliminate selection effects. ETGs were selected from both samples via visual classifications using SDSS images. Further details can be found in Rowlands et al. (2012). Physical parameters are derived for each galaxy using the multiwavelength spectral energy distribution (SED) fitting code of da Cunha, Charlot and Elbaz (2008), Smith et al. 2012, using an energy balance argument. We investigate the differences between the dusty ETGs and the general ETG population, and find that the H-ATLAS ETGs are more than an order of magnitude dustier than the control ETGs. The mean dust mass of the 42 H-ATLAS ETGs is 5.5 × 107M⊙ (comparable to the dust mass of spirals in our sample), whereas the dust mass of the 233 control ETGs inferred from stacking at optical positions on the 250μm map is (0.8 - 4.0) × 106M⊙ for 25-15 K dust. The average star-formation rate of the H-ATLAS ETGs is 1.0 dex higher than that of control ETGs, and the mean r-band light-weighted age of the H-ATLAS ETGs is 1.8 Gyr younger than the control ETGs. The rest-frame NUV - r colours of the H-ATLAS ETGs are 1.0 magnitudes bluer than the control ETGs, and some ETGs may be transitioning from the blue cloud to the red sequence. Some H-ATLAS ETGs
Io's volcanic influence on the Io plasma torus: HISAKI observation in 2015
Tsuchiya, F.; Yoshioka, K.; Kimura, T.; Murakami, G.; Yoneda, M.; Koga, R.; Kagitani, M.; Sakanoi, T.; Kasaba, Y.; Yamazaki, A.; Yoshikawa, I.
2015-12-01
The satellite Io which has many active volcanos supplies volcanic gases to the Jovian magnetosphere with typical rate of 1 ton/sec and has been known be a primary source of plasmas in the magnetosphere. Change in the volcanic activity on Io should cause change of the supply rate and could affect structure of the magnetosphere and dynamics occurs in it. However, responses of the magnetosphere to the volcanic activity is still not fully understood; one of the reasons is lack of continuous and long term observations of Io' volcanic gas extended around Io, plasmas in the Io torus, and activity of the magnetosphere. The extreme ultraviolet (EUV) spectroscope, EXCEED, onboard the HISAKI satellite has capability to measure ion and atomic emission lines in EUV range (55-145nm) and is dedicated to observing solar system planets. The satellite has been successfully launched on Sep. 2013 and 2nd campaign of Io plasma torus and Jovian northern EUV aurora observation has been done from the end of Nov. 2014 to middle of May 2015. On middle of Jan. 2015, HISAKI detected gradual increase in intensity of S+ emission lines and decrease of S3+ ones in the plasma torus. The S+ intensity showed a maximum around the end of Feb. and S++ and S3+ intensities also showed maxima subsequently. Simultaneous ground based observation of the sodium nebula showed increase of the emission intensity from the middle of Jan. to the beginning of Mar. These observations suggest that the volcanic activity began at the middle of Jan. and increase neutral atom and ion densities in the Io torus. The intensities of S+ and S2+ ions returned to the pre-increase level by the middle of May 2015. S3+ had still been in the decay phase at the end of the observation. Change in radial structure of the plasma torus was also found during the volcanic event. The intensity of S+ ion began to increase around the orbit of Io (6 Jovian radii). The brightened region propagated outward and reached at 8.5 Jovian radii from
From Canards of Folded Singularities to Torus Canards in a Forced van der Pol Equation
Burke, John; Desroches, Mathieu; Granados, Albert; Kaper, Tasso J.; Krupa, Martin; Vo, Theodore
2016-04-01
In this article, we study canard solutions of the forced van der Pol equation in the relaxation limit for low-, intermediate-, and high-frequency periodic forcing. A central numerical observation made herein is that there are two branches of canards in parameter space which extend across all positive forcing frequencies. In the low-frequency forcing regime, we demonstrate the existence of primary maximal canards induced by folded saddle nodes of type I and establish explicit formulas for the parameter values at which the primary maximal canards and their folds exist. Then, we turn to the intermediate- and high-frequency forcing regimes and show that the forced van der Pol possesses torus canards instead. These torus canards consist of long segments near families of attracting and repelling limit cycles of the fast system, in alternation. We also derive explicit formulas for the parameter values at which the maximal torus canards and their folds exist. Primary maximal canards and maximal torus canards correspond geometrically to the situation in which the persistent manifolds near the family of attracting limit cycles coincide to all orders with the persistent manifolds that lie near the family of repelling limit cycles. The formulas derived for the folds of maximal canards in all three frequency regimes turn out to be representations of a single formula in the appropriate parameter regimes, and this unification confirms the central numerical observation that the folds of the maximal canards created in the low-frequency regime continue directly into the folds of the maximal torus canards that exist in the intermediate- and high-frequency regimes. In addition, we study the secondary canards induced by the folded singularities in the low-frequency regime and find that the fold curves of the secondary canards turn around in the intermediate-frequency regime, instead of continuing into the high-frequency regime. Also, we identify the mechanism responsible for this
... for Parents/Teachers Resource Links for Students Glossary Nuclear Medicine What is nuclear medicine? What are radioactive ... NIBIB-funded researchers advancing nuclear medicine? What is nuclear medicine? Nuclear medicine is a medical specialty that ...
Balokovic, Mislav; Harrison, Fiona; Brightman, Murray
2017-08-01
The obscuring torus is one of the main components of the basic unified model of active galactic nuclei (AGN), needed to create anisotropy in obscuration as a function of the viewing angle. We present the first study of the geometrical properties of the AGN torus in a large and representative sample of type II Seyfert nuclei. The sample consists of 124 AGN selected in the hard X-ray band from the Swift/BAT 70-month catalog and observed simultaneously with NuSTAR and Swift/XRT. These data enable us to explore the constraints that observed spectra place on the properties of the obscuring torus in individual AGN and in the local population of Seyfert II nuclei. We make use of empirically motivated spectral models for X-ray reprocessing in approximately toroidal geometry for constraining the distribution of the average column density of the torus, and the distribution of the torus covering factor within this sample. We find that the torus-averaged column density is independent of the line-of-sight column density, with typical column density that is borderline Compton-thick, i.e., around the unity optical depth for Compton scattering. The distribution of torus covering factors is broad but shows a preference for high covering, peaking around the covering factor of 90%, with the median at 70%, in agreement with recent sample studies in the infrared band. We also examine the dependence of the covering factor on intrinsic luminosity, finding that the median covering factor peaks around the intrinsic X-ray luminosity of 10^42.5 erg/s and decreases toward both lower and higher luminosities.
2011-04-01
Models of planets forming from dusty discs around young stars have taken concrete shape over the past decade as observational data have improved and the number of exoplanetary systems discovered has climbed above 500.
Energy Technology Data Exchange (ETDEWEB)
S. Dartevelle
2005-09-05
The objective of this manuscript is to fully derive a geophysical multiphase model able to ''accommodate'' different multiphase turbulence approaches; viz., the Reynolds Averaged Navier-Stokes (RANS), the Large Eddy Simulation (LES), or hybrid RANSLES. This manuscript is the first part of a larger geophysical multiphase project--lead by LANL--that aims to develop comprehensive modeling tools for large-scale, atmospheric, transient-buoyancy dusty jets and plume (e.g., plinian clouds, nuclear ''mushrooms'', ''supercell'' forest fire plumes) and for boundary-dominated geophysical multiphase gravity currents (e.g., dusty surges, diluted pyroclastic flows, dusty gravity currents in street canyons). LES is a partially deterministic approach constructed on either a spatial- or a temporal-separation between the large and small scales of the flow, whereas RANS is an entirely probabilistic approach constructed on a statistical separation between an ensemble-averaged mean and higher-order statistical moments (the so-called ''fluctuating parts''). Within this specific multiphase context, both turbulence approaches are built up upon the same phasic binary-valued ''function of presence''. This function of presence formally describes the occurrence--or not--of any phase at a given position and time and, therefore, allows to derive the same basic multiphase Navier-Stokes model for either the RANS or the LES frameworks. The only differences between these turbulence frameworks are the closures for the various ''turbulence'' terms involving the unknown variables from the fluctuating (RANS) or from the subgrid (LES) parts. Even though the hydrodynamic and thermodynamic models for RANS and LES have the same set of Partial Differential Equations, the physical interpretations of these PDEs cannot be the same, i.e., RANS models an averaged field, while LES simulates a
Yoshioka, K.; Tsuchiya, F.; Kimura, T.; Kagitani, M.; Murakami, G.; Yamazaki, A.; Kuwabara, M.; Suzuki, F.; Hikida, R.; Yoshikawa, I.; Bagenal, F.; Fujimoto, M.
2017-03-01
The Io plasma torus, situated in the Jovian inner magnetosphere (6-8 Jovian radii from the planet) is filled with heavy ions and electrons, a large part of which are derived from Io's volcanos. The torus is the key area connecting the primary source of plasma (Io) with the midmagnetosphere (>10 Jovian radii), where highly dynamic phenomena are taking place. Revealing the plasma behavior of the torus is a key factor in elucidating Jovian magnetospheric dynamics. A global picture of the Io plasma torus can be obtained via spectral diagnosis of remotely sensed ion emissions generated via electron impact excitation. Hisaki, an Earth-orbiting spacecraft equipped with an extreme ultraviolet spectrograph Extreme Ultraviolet Spectroscope for Exospheric Dynamics, has observed the torus at moderate spectral resolution. The data have been submitted to spectral analysis and physical chemistry modeling under the assumption of axial symmetry. Results from the investigation are radial profiles of several important parameters including electron density and temperature as well as ion abundances. The inward transport timescale of midmagnetospheric plasma is obtained to be 2-40 h from the derived radial profile for the abundance of suprathermal electrons. The physical chemistry modeling results in a timescale for the outward transport of Io-derived plasma of around 30 days. The ratio between inward and outward plasma speed ( 1%) is consistent with the occurrence rate of depleted flux tubes determined using in situ observations by instruments on the Galileo spacecraft.
Topological Strings, Two-Dimensional Yang-Mills Theory and Chern-Simons Theory on Torus Bundles
Caporaso, N; Griguolo, L; Pasquetti, S; Seminara, D; Szabó, R J
2006-01-01
We study the relations between two-dimensional Yang-Mills theory on the torus, topological string theory on a Calabi-Yau threefold whose local geometry is the sum of two line bundles over the torus, and Chern-Simons theory on torus bundles. The chiral partition function of the Yang-Mills gauge theory in the large N limit is shown to coincide with the topological string amplitude computed by topological vertex techniques. We use Yang-Mills theory as an efficient tool for the computation of Gromov-Witten invariants and derive explicitly their relation with Hurwitz numbers of the torus. We calculate the Gopakumar-Vafa invariants, whose integrality gives a non-trivial confirmation of the conjectured nonperturbative relation between two-dimensional Yang-Mills theory and topological string theory. We also demonstrate how the gauge theory leads to a simple combinatorial solution for the Donaldson-Thomas theory of the Calabi-Yau background. We match the instanton representation of Yang-Mills theory on the torus with ...
Energy Technology Data Exchange (ETDEWEB)
Diez-Jimenez, Efren, E-mail: ediez@ing.uc3m.e [Departamento de Ingenieria Mecanica, Universidad Carlos III de Madrid, Butarque, 15, E28911 Leganes (Spain); Sander, Berit; Timm, Lauri; Perez-Diaz, Jose-Luis [Departamento de Ingenieria Mecanica, Universidad Carlos III de Madrid, Butarque, 15, E28911 Leganes (Spain)
2011-04-15
Research highlights: {yields} A local model is used to demonstrate a flip effect in the orientation of a magnet over a superconductor. {yields} A superconducting torus shape is studied. {yields} Increasing the inner radius of the torus elevates the flip effect point. {yields} There are linear piecewises in the geometrical dependency functions that help to fit the flip effect point. - Abstract: In a previous study, a general local model was used in order to demonstrate the apparition of a flip effect in the equilibrium orientation of a magnet when it is over a superconducting torus. This effect can be easily used in devices such as binary position detectors for magneto-microscopy, contactless sieves or magnetic levels amongst others. We present an initial study useful to design devices based on the flip effect between magnets and torus superconductors. It demonstrates that varying different geometrical parameters the flip effect point can be fixed. Also, it can be observed that increasing the inner radius of the torus elevates the flip effect point. A magneto-mechanical explanation of this phenomenon is exposed. For an increment of cross-section diameter occurs the same behavior. There are linear piecewises in the geometrical dependency functions that can be used for a more accurate fitting of the flip effect point.
Self-Diffusion in 2D Dusty Plasma Liquids: Numerical Simulation Results
Hou, Lu-Jing; Shukla, P K
2008-01-01
We perform Brownian dynamics simulations for studying the self-diffusion in two-dimensional (2D) dusty plasma liquids, in terms of both mean-square displacement and velocity autocorrelation function (VAF). Super-diffusion of charged dust particles has been observed to be most significant at infinitely small damping rate $\\gamma$ for intermediate coupling strength, where the long-time asymptotic behavior of VAF is found to be the product of $t^{-1}$ and $\\exp{(-\\gamma t)}$. The former represents the prediction of early theories in 2D simple liquids and the latter the VAF of a free Brownian particle. This leads to a smooth transition from super-diffusion to normal diffusion, and then to sub-diffusion with an increase of the damping rate. These results well explain the seemingly contradictory scattered in recent classical molecular dynamics simulations and experiments of dusty plasmas.
Linear and nonlinear dynamics of current-driven waves in dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Ahmad, Ali [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Ali Shan, S.; Haque, Q. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Saleem, H. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan)
2012-09-15
The linear and nonlinear dynamics of a recently proposed plasma mode of dusty plasma is studied using kappa distribution for electrons. This electrostatic wave can propagate in the plasma due to the sheared flow of electrons and ions parallel to the external magnetic field in the presence of stationary dust. The coupling of this wave with the usual drift wave and ion acoustic wave is investigated. D'Angelo's mode is also modified in the presence of superthermal electrons. In the nonlinear regime, the wave can give rise to dipolar vortex structures if the shear in flow is weaker and tripolar vortices if the flow has steeper gradient. The results have been applied to Saturn's magnetosphere corresponding to negatively charged dust grains. But the theoretical model is applicable for positively charged dust as well. This work will be useful for future observations and studies of dusty environments of planets and comets.
Perna, R; Fiore, F; Perna, Rosalba; Lazzati, Davide; Fiore, Fabrizio
2003-01-01
The interaction of a radiation field with a dusty medium is a relevant issue in several astrophysical contexts. We use the time-dependent photoionization code in a dusty medium developed by Perna & Lazzati (2002), to study the modifications in the dust distribution and the relative optical opacities when a strong X-ray UV radiation flux propagates into a medium. We find that silicates are preferentially destroyed with respect to graphite, and the extinction curve becomes significantly flatter (hence implying less reddening), with the characteristic bump at lambda 2175 A highly suppressed, due to the destruction of the small graphite grains. This could explain the observational lack of such a feature in GRB afterglow and AGN spectra. For a very intense and highly variable source irradiating a compact and dense region, time variability in the optical opacity resulting from dust destruction can be observed on a relatively short timescale. We show that, under these circumstances, monitoring the time variabili...
Experimental and computational characterization of a modified GEC cell for dusty plasma experiments
Land, Victor; Smith, Bernard; Matthews, Lorin; Hyde, Truell
2009-01-01
A self-consistent fluid model developed for simulations of micro- gravity dusty plasma experiments has for the first time been used to model asymmetric dusty plasma experiments in a modified GEC reference cell with gravity. The numerical results are directly compared with experimental data and the experimentally determined dependence of global discharge parameters on the applied driving potential and neutral gas pressure is found to be well matched by the model. The local profiles important for dust particle transport are studied and compared with experimentally determined profiles. The radial forces in the midplane are presented for the different discharge settings. The differences between the results obtained in the modified GEC cell and the results first reported for the original GEC reference cell are pointed out.
Observation of dust acoustic multi-solitons in a strongly coupled dusty plasma
Boruah, A.; Sharma, S. K.; Nakamura, Y.; Bailung, H.
2016-09-01
The excitation and propagation of low frequency dust acoustic multi-solitons are investigated in an unmagnetized strongly coupled dusty plasma. A floating 2D dusty medium is produced in an RF discharge Ar plasma with silica micro-particles. Dust acoustic perturbations are excited by applying a negative sinusoidal pulse of frequency 1-2 Hz and amplitude 4-20 V to an exciter grid. An initial large amplitude dust density compression breaks into a number of solitary pulses which are identified as dust acoustic solitons. The observed multi-soliton evolution is compared with numerical simulations of modified Korteweg de Vries (KdV)-Burger equation. The characteristics of the generated solitons are in good agreement with the theory.
On the Detection of Non-Transiting Exoplanets with Dusty Tails
DeVore, John; Sanchis-Ojeda, Roberto; Hoffman, Kelsey; Rowe, Jason
2016-01-01
We present a way of searching for non-transiting exoplanets with dusty tails. In the transiting case, the extinction by dust during the transit removes more light from the beam than is scattered into it. Thus, the forward scattering component of the light is best seen either just prior to ingress, or just after egress, but with reduced amplitude over the larger peak that is obscured by the transit. This picture suggests that it should be equally productive to search for positive-going peaks in the flux from non-transiting exoplanets with dusty tails. We discuss what amplitudes are expected for different orbital inclination angles. The signature of such objects should be distinct from normal transits, starspots, and most - but not all - types of stellar pulsations.
Interactions of a Projectile Charge with Two-Dimensional Dusty Plasmas
Institute of Scientific and Technical Information of China (English)
JIANG Ke; HOU Lu-Jing; WANG You-Nian
2005-01-01
@@ The interactions of a moving charge (namely, one additional dust particle) with a two-dimensional dusty plasma in gas discharge experiment are studied by means of the linearized hydrodynamic theory for the dusty plasma.Expressions are derived for the induced potential and the stopping power of the moving charge, when the charge flights parallel to and over the dust layer. The numerical results are obtained for different discharge pressures and different distances from the moving charge to the dust layer. The results show that the moving charge excites a V-shaped disturbance of induced potential or the so-called Mach cone in the dust layer, while the charge itself loses its energy.
Dusty plasma in a glow discharge in helium in temperature range of 5–300 K
Energy Technology Data Exchange (ETDEWEB)
Samoilov, I. S.; Baev, V. P.; Timofeev, A. V., E-mail: timofeevalvl@gmail.com; Amirov, R. Kh.; Kirillin, A. V.; Nikolaev, V. S.; Bedran, Z. V. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)
2017-03-15
Dusty plasma structures in glow discharge in helium in the temperature range of 5–300 K are investigated experimentally. We have described the experimental setup that makes it possible to continuously vary the temperature regime. The method for experimental data processing has been described. We have measured interparticle distances in the temperature range of 9–295 K and compared them with the Debye radius. We indicate the ranges of variations in experimental parameters in which plasma–dust structures are formed and various types of their behavior are manifested (rotation, vibrations of structures, formation of vertical linear chains, etc.). The applicability of the Yukawa potential to the description of the structural properties of a dusty plasma in the experimental conditions is discussed.
Chemically reacting dusty viscoelastic fluid flow in an irregular channel with convective boundary
Directory of Open Access Journals (Sweden)
R. Sivaraj
2013-03-01
Full Text Available In this paper, we have studied the combined effects of free convective heat and mass transfer on an unsteady MHD dusty viscoelastic (Walters liquid model-B fluid flow between a vertical long wavy wall and a parallel flat wall saturated with porous medium subject to the convective boundary condition. The coupled partial differential equations are solved analytically using perturbation technique. The velocity, temperature and concentration fields have been studied for various combinations of physical parameters such as magnetic field, heat absorption, thermal radiation, radiation absorption, Biot number and chemical reaction parameters. The skin friction, Nusselt number and Sherwood number are also presented and displayed graphically. Further, it is observed that the velocity profiles of dusty fluid are higher than the dust particles.
Energy Technology Data Exchange (ETDEWEB)
Song, Y.L. [College of Science, China Agricultural University, Beijing 100083 (China); Huang, F., E-mail: huangfeng@cau.edu.cn [College of Science, China Agricultural University, Beijing 100083 (China); Chen, Z.Y., E-mail: chenzy@mail.buct.edu.cn [Department of Physics, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Laser Propulsion & Application, Beijing 101416 (China); Liu, Y.H. [School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025 (China); Yu, M.Y. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44801 Bochum (Germany)
2016-02-22
Negatively charged dust particles immersed in 2-dimensional dusty plasma system are investigated by molecular dynamics simulations. The effects of the confinement potential and attraction interaction potential on dust particle self-organization are studied in detail and two typical dust particle distributions are obtained when the system reaches equilibrium. The average radial velocity (ARV), average radial force (ARF) and radial mean square displacement are employed to analyze the dust particles' dynamics. Both ARVs and ARFs exhibit oscillation behaviors when the simulation system reaches equilibrium state. The relationships between the oscillation and confinement potential and attraction potential are studied in this paper. The simulation results are qualitatively similar to experimental results. - Highlights: • Self-organization and oscillation of a 2-dimensional dusty plasma is investigated. • Effect of the confinement potential on dust self-organization and oscillation is given. • Effect of the attraction potential on dust self-organization and oscillation is studied.
Solitary Kinetic Alfven Waves in a Low-β Dusty Plasma
Institute of Scientific and Technical Information of China (English)
CHEN Yin-Hua; LU Wei
2000-01-01
The nonlinear kinetic Alfven waves in a low-β(0<β<1)dusty plasma have been investigated with the fluid model of three-component plasma. The nonlinear equation governing the perturbation density of electrons in a form of the energy integral has been derived. In the approximation of small amplitude, the soliton solution for the perturbation density of electrons is found, and the characteristics of solitons in different range of plasma parameters is studied numerically. The results show that the density dip or hump can be formed in a dusty plasma for different ranges of parameters, the amplitude of density dip is enhanced and the amplitude of density hump is reduced with increasing dust grain content.
Optical diagnostic and electrical analysis in dusty RF discharges containing plasmoids
Energy Technology Data Exchange (ETDEWEB)
Lagrange, J. F.; Géraud-Grenier, I.; Massereau-Guilbaud, V., E-mail: Veronique.massereau@univ-orleans.fr [GREMI, Groupe de Recherche sur l' Energétique des Milieux Ionisés, UMR 7344 CNRS/Université d' Orléans, Site de l' IUT de Bourges, 63 avenue de Lattre de Tassigny, 18020 Bourges Cedex (France); Faubert, F. [IUT de Bourges, Département Mesures Physiques, 63 avenue de Lattre de Tassigny, 18020 Bourges Cedex (France)
2015-10-28
The presence of hydrogenated carbon nitride a-CN{sub x}:H particles confined in an argon dusty discharge induces the appearance of instabilities. Those instabilities, also called plasmoids, are luminous regions which move through the plasma and rotate around the biased electrode circumference. Electrical characteristics of the plasma have been used to evidence the presence of dust particles and to demonstrate that plasmoid appearance is triggered by particles. The light emitted by the plasma is analysed by optical emission spectroscopy. This paper presents the spatial distribution of excited species, such as CN, Ar I… between electrodes both inside plasmoids and in the surrounding dusty plasma. Obtained results allow to get information for the electron energy distribution function. Moreover, the interplay between plasmoid behaviour and particle presence in the plasma is shown.
Low-frequency electrostatic dust-modes in a non-uniform magnetized dusty plasma
Indian Academy of Sciences (India)
S S Duha; S K Paul; A K Banerjee; A A Mamun
2004-11-01
A self-consistent and general description of obliquely propagating low-frequency electrostatic dust-modes in a non-uniform magnetized dusty plasma system has been presented. A number of different situations, which correspond to different low-frequency electrostatic dust-modes, namely, dust-acoustic mode, dust-drift mode, dust-cyclotron mode, dust-lower-hybrid mode, and other associated modes (such as, accelerated and retarded dust-acoustic modes, accelerated and retarded dust-lower-hybrid modes, etc.), have also been investigated. It has been shown that the effects of obliqueness and inhomogeneities in plasma particle number densities introduce new electrostatic dust modes as well as significantly modify the dispersion properties of the other low-frequency electrostatic dust associated modes. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring-systems and cometary tails, are briefly mentioned.
Filamentation instability of current-driven dust ion-acoustic waves in a collisional dusty plasma
Energy Technology Data Exchange (ETDEWEB)
Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran 19839-63113 (Iran, Islamic Republic of); Haghtalab, T.; Khorashadizadeh, S. M. [Physics Department, Birjand University, Birjand 97179-63384 (Iran, Islamic Republic of)
2011-11-15
A theoretical investigation has been made of the dust ion-acoustic filamentation instability in an unmagnetized current-driven dusty plasma by using the Lorentz transformation formulas. The effect of collision between the charged particles with neutrals and their thermal motion on this instability is considered. Developing the filamentation instability of the current-driven dust ion-acoustic wave allows us to determine the period and the establishment time of the filamentation structure and threshold for instability development.
Dust acoustic solitary and shock waves in strongly coupled dusty plasmas with nonthermal ions
Indian Academy of Sciences (India)
Hamid Reza Pakzad; Kurosh Javidan
2009-11-01
The Korteweg–de Vries–Burgers (KdV–Burgers) equation and modified Korteweg–de Vries–Burgers equation are derived in strongly coupled dusty plasmas containing nonthermal ions and Boltzmann distributed electrons. It is found that solitary waves and shock waves can be produced in this medium. The effects of important parameters such as ion nonthermal parameter, temperature, density and velocity on the properties of shock waves and solitary waves are discussed.
Suppression of Instability in Strongly Coupled Dusty Plasmas with Ion Flow
Institute of Scientific and Technical Information of China (English)
贺凯芬; 谢柏松; 刘克富
2001-01-01
The instability of low-frequency longitudinal modes in strongly coupled dusty plasmas with an ion flow is investigated. The dust charging relaxation is taken into account. It is found that when the ion flow is strong enough,the suppression, even disappearance. of instability can occur. Similar to that of the real frequency of waves, the imaginary part of waves also exhibits a transition, which arises from the sensitive dependences on the system parameters and their competition.
Dust-Acoustic Waves in Strongly Coupled Dusty Plasmas Containing Variable-Charge Impurities
Institute of Scientific and Technical Information of China (English)
XIE Bai-Song; HE Kai-Fen; M. Y. Yu
2000-01-01
A relatively self-consistent theory of dust-acoustic waves in the strongly coupled dusty plasmas containing variable charge impurities is given. Relevant physical processes such as dust elastic relaxation and dust charge relaxation are taken into account. It is shown that the negative dispersion of dust-acoustic waves due to the strong correlation of dusts is enhanced in the presence of dust-neutral collisions.
Generalized polarization force acting on dust grains in a dusty plasma
Bentabet, Karima; Mayout, Saliha; Tribeche, Mouloud
2017-01-01
The polarization force acting on dust particles in a dusty plasma is revisited within the theoretical framework of the Tsallis statistical mechanics. The generalized nonextensive polarization force expression is derived. As application, the modifications arising in the propagation of dust-acoustic solitary waves, and dust sheath formation are analyzed. Our results should be of wide relevance to explain and interpret the sheath formation and its structure in nonequilibrium plasmas related process such as surface treatments and ion implantation.
Impurity-induced local modes in one-dimensional dusty plasma chains
Institute of Scientific and Technical Information of China (English)
Ren Yong-Chao; Wang Xin-Shang; Wang Xiao-Gang
2012-01-01
The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied.It is found that local modes can be excited besides lattice waves,due to the existence of an impurity particle.The dispersion relations of the modes are derived accordingly.Properties of the lattice and local modes are also analyzed and discussed,particularly for their symmetric features and conditions of the mode excitation.
Killer, Carsten; Bockwoldt, Tim; Schütt, Stefan; Himpel, Michael; Melzer, André; Piel, Alexander
2016-03-18
The phase separation in binary mixtures of charged particles has been investigated in a dusty plasma under microgravity on parabolic flights. A method based on the use of fluorescent dust particles was developed that allows us to distinguish between particles of slightly different size. A clear trend towards phase separation even for smallest size (charge) disparities is observed. The diffusion flux is directly measured from the experiment and uphill diffusion coefficients have been determined.
Dust-acoustic solitary waves in dusty plasma with variable dust charge
Forozani, Gh
2011-01-01
In this article we are going to consider dust acoustic wave in dusty plasma whose constituents are inertial negative charged dust particles, Boltzmann distributed electrons and non-thermal distributed ions with variable dust charge. Using reductive perturbation method, we have obtained Korteweg-de Veries (kdv) and modified kdv(mkdv) equations. A Sagdeev potential for the system and stability conditions for solitonic solution are also derived.
Active galactic nucleus torus models and the puzzling infrared spectrum of IRAS F10214+4724
Efstathiou, A.; Christopher, N.; Verma, A.; Siebenmorgen, R.
2013-12-01
We present a revised model for the infrared emission of the hyperluminous infrared galaxy IRAS F10214+4724 which takes into account recent photometric data from Spitzer and Herschel that sample the peak of its spectral energy distribution. We first present and discuss a grid of smooth active galactic nucleus (AGN) torus models computed with the method of Efstathiou & Rowan-Robinson and demonstrate that the combination of these models and the starburst models of Efstathiou and coworkers, while able to give an excellent fit to the average spectrum of Seyfert 2s and spectra of individual type 2 quasars measured by Spitzer, fails to match the spectral energy distribution of IRAS F10214+4724. This is mainly due to the fact that the νSν distribution of the galaxy falls very steeply with increasing frequency (a characteristic that is usually indicative of heavy absorption by dust) but shows a silicate feature in emission. Such emission features are not expected in sources with optical/near-infrared type 2 AGN spectral signatures. The Herschel data show that there is more power emitted in the rest-frame 20-50 μm wavelength range compared with the model presented by Efstathiou which assumes three components of emission: an edge-on torus, clouds (at a temperature of 610 and 200 K) that are associated with the narrow-line region (NLR) and a highly obscured starburst that dominates in the submillimetre. We present a revised version of that model that assumes an additional component of emission which we associate with NLR clouds at a temperature of 100 K. The 100 K dust component could also be explained by a highly obscured hot starburst. The model suggests that the NLR of IRAS F10214+4724 has an unusually high covering factor (≥17 per cent) or more likely the magnification of the emission from the NLR clouds is significantly higher than that of the emission from the torus.
Perturbed soliton excitations of Rao-dust Alfvén waves in magnetized dusty plasmas
Energy Technology Data Exchange (ETDEWEB)
Kavitha, L., E-mail: louiskavitha@yahoo.co.in [Department of Physics, School of Basic and Applied Sciences, Central University of Tamil Nadu, Thiruvarur 610 101 (India); The Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Lavanya, C.; Senthil Kumar, V. [Department of Physics, Periyar University, Salem, Tamil Nadu 636 011 (India); Gopi, D. [Department of Chemistry, Periyar University, Salem 636 011 (India); Center for Nanoscience and Nanotechnology, Periyar University, Salem, Tamil Nadu 636 011 (India); Pasqua, A. [Department of Physics, University of Trieste, Trieste (Italy)
2016-04-15
We investigate the propagation dynamics of the perturbed soliton excitations in a three component fully ionized dusty magnetoplasma consisting of electrons, ions, and heavy charged dust particulates. We derive the governing equation of motion for the two dimensional Rao-dust magnetohydrodynamic (R-D-MHD) wave by employing the inertialess electron equation of motion, inertial ion equation of motion, the continuity equations in a plasma with immobile charged dust grains, together with the Maxwell's equations, by assuming quasi neutrality and neglecting the displacement current in Ampere's law. Furthermore, we assume the massive dust particles are practically immobile since we are interested in timescales much shorter than the dusty plasma period, thereby neglecting any damping of the modes due to the grain charge fluctuations. We invoke the reductive perturbation method to represent the governing dynamics by a perturbed cubic nonlinear Schrödinger (pCNLS) equation. We solve the pCNLS, along the lines of Kodama-Ablowitz multiple scale nonlinear perturbation technique and explored the R-D-MHD waves as solitary wave excitations in a magnetized dusty plasma. Since Alfvén waves play an important role in energy transport in driving field-aligned currents, particle acceleration and heating, solar flares, and the solar wind, this representation of R-D-MHD waves as soliton excitations may have extensive applications to study the lower part of the earth's ionosphere.
Directory of Open Access Journals (Sweden)
N. Sandeep
2016-03-01
Full Text Available We analyzed the unsteady magnetohydrodynamic radiative flow and heat transfer characteristics of a dusty nanofluid over an exponentially permeable stretching surface in presence of volume fraction of dust and nano particles. We considered two types of nanofluids namely Cu-water and CuO-water embedded with conducting dust particles. The governing equations are transformed into nonlinear ordinary differential equations by using similarity transformation and solved numerically using Runge–Kutta based shooting technique. The effects of non-dimensional governing parameters namely magneticfield parameter, mass concentration of dust particles, fluid particle interaction parameter, volume fraction of dust particles, volume fraction of nano particles, unsteadiness parameter, exponential parameter, radiation parameter and suction/injection parameter on velocity profiles for fluid phase, dust phase and temperature profiles are discussed and presented through graphs. Also, friction factor and Nusselt numbers are discussed and presented for two dusty nanofluids separately. Comparisons of the present study were made with existing studies under some special assumptions. The present results have an excellent agreement with existing studies. Results indicated that the enhancement in fluid particle interaction increases the heat transfer rate and depreciates the wall friction. Also, radiation parameter has the tendency to increase the temperature profiles of the dusty nanofluid.
SEM/EDS characterisation of dusty deposits in precipitation and assessment of their origin
Directory of Open Access Journals (Sweden)
Miloš Miler
2014-07-01
Full Text Available Detailed scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS analysis of dusty material in rainfall residue, deposited and collected on February 19th 2014 in Ljubljana, was carried out with the intention to characterise it according to its chemical and mineral composition and to assess its origin. The material consists of poorly sorted and sharp-edged particles of mostly very fine-grained silt and clay fractions, which is consistent with long-range aerial transport. Particles are represented by illite, chlorite and kaolinite group clay minerals, quartz, feldspars, carbonates, accessory minerals and secondary Fe-oxy-hydroxide minerals. Quantities of minerals and illite/ kaolinite ratio (4.5 correspond to dusts in rainfall residues originating from Moroccan Atlas, while chlorite/kaolinite ratio (2.8 agrees better with dust from central Libya. The element ratios Al/Si, Ca/Al, K/Ca, Mg/Al, Fe/Al and (Ca+Mg/Fe in the studied dusty deposit are in good agreement with ratios in dusts from rainfall residues originating from Morocco and northern Mauritania. This was also confirmed by the trajectories of cloud movement that caused precipitation with dusty deposit, although the back trajectory HYSPLIT simulation of air masses indicated northern Mauritania, central Niger, southern Algeria, southwestern and central Libya as the most possible source regions.
Dusty Plasma Experimental (DPEx) device for complex plasma experiments with flow
Jaiswal, S; Sen, A
2015-01-01
A versatile table-top dusty plasma experimental device (DPEx) to study flow induced excitations of linear and nonlinear waves/structures in a complex plasma is presented. In this $\\Pi$-shaped apparatus a DC glow discharge plasma is produced between a disc shaped anode and a grounded long cathode tray by applying a high voltage DC in the background of a neutral gas and subsequently a dusty plasma is created by introducing micron sized dust particles that get charged and levitated in the sheath region. A flow of the dust particles is induced in a controlled manner by adjusting the pumping speed and the gas flow rate into the device. A full characterisation of the plasma, using Langmuir and emissive probe data, and that of the dusty plasma using particle tracking data with the help of an idl based (super) Particle Identification and Tracking (sPIT) code is reported. Experimental results on the variation of the dust flow velocity as a function of the neutral pressure and the gas flow rate are given. The potential...
Dippers and dusty disc edges: new diagnostics and comparison to model predictions
Bodman, Eva H. L.; Quillen, Alice C.; Ansdell, Megan; Hippke, Michael; Boyajian, Tabetha S.; Mamajek, Eric E.; Blackman, Eric G.; Rizzuto, Aaron; Kastner, Joel H.
2017-09-01
We revisit the nature of large dips in flux from extinction by dusty circumstellar material that is observed by Kepler for many young stars in the Upper Sco and ρ Oph star formation regions. These young, low-mass 'dipper' stars are known to have low accretion rates and primarily host moderately evolved dusty circumstellar discs. Young low-mass stars often exhibit rotating starspots that cause quasi-periodic photometric variations. We found no evidence for periods associated with the dips that are different from the starspot rotation period in spectrograms constructed from the light curves. The material causing the dips in most of these light curves must be approximately corotating with the star. We find that disc temperatures computed at the disc corotation radius are cool enough that dust should not sublime. Crude estimates for stellar magnetic field strengths and accretion rates are consistent with magnetospheric truncation near the corotation radius. Magnetospheric truncation models can explain why the dips are associated with material near corotation and how dusty material is lifted out of the mid-plane to obscure the star that would account for the large fraction of young low-mass stars that are dippers. We propose that variations in disc orientation angle, stellar magnetic field dipole tilt axis and disc accretion rate are underlying parameters accounting for differences in the dipper light curves.
Single-Camera Stereoscopy Setup to Visualize 3D Dusty Plasma Flows
Romero-Talamas, C. A.; Lemma, T.; Bates, E. M.; Birmingham, W. J.; Rivera, W. F.
2016-10-01
A setup to visualize and track individual particles in multi-layered dusty plasma flows is presented. The setup consists of a single camera with variable frame rate, and a pair of adjustable mirrors that project the same field of view from two different angles to the camera, allowing for three-dimensional tracking of particles. Flows are generated by inclining the plane in which the dust is levitated using a specially designed setup that allows for external motion control without compromising vacuum. Dust illumination is achieved with an optics arrangement that includes a Powell lens that creates a laser fan with adjustable thickness and with approximately constant intensity everywhere. Both the illumination and the stereoscopy setup allow for the camera to be placed at right angles with respect to the levitation plane, in preparation for magnetized dusty plasma experiments in which there will be no direct optical access to the levitation plane. Image data and analysis of unmagnetized dusty plasma flows acquired with this setup are presented.
Dusty plasma sheath-like structure in the lunar terminator region
Popel, Sergey; Zelenyi, Lev; Atamaniuk, Barbara
2016-07-01
The main properties of the dusty plasma layer near the surface over the illuminated and dark parts of the Moon are described. They are used to realize dusty plasma behaviour and to determine electric fields over the terminator region. Possibility of the existence of a dusty plasma sheath-like structure [1] in the region of lunar terminator is shown. The electric fields excited in the terminator region are demonstrated to be on the order of 300 V/m. These electric fields can result in rise of dust particles of the size of a few micrometers up to an altitude of about 30 cm over the lunar surface that explains the effect of ``horizon glow" observed at the terminator by Surveyor lunar lander. This work was supported in part by the Presidium of the Russian Academy of Sciences (under Fundamental Research Program No. 7, ``Experimental and Theoretical Study of the Solar System Objects and Stellar Planet Systems. Transient Explosion Processes in Astrophysics" and the Russian Foundation for Basic Research (Project No. 15-02-05627-a). [1] S. I. Popel, L. M. Zelenyi, and B. Atamaniuk, Phys. Plasmas 22, 123701 (2015); doi: 10.1063/1.4937368.
Longitudinal singular response of dusty plasma medium in weak and strong coupling limits
Energy Technology Data Exchange (ETDEWEB)
Kumar Tiwari, Sanat; Das, Amita; Kaw, Predhiman; Sen, Abhijit [Institute for Plasma Research, Bhat, Gandhinagar - 382428 (India)
2012-01-15
The longitudinal response of a dusty plasma medium in both weak and strong coupling limits has been investigated in detail using analytic as well as numerical techniques. In particular, studies on singular response of the medium have been specifically investigated here. A proper Galilean invariant form of the generalized hydrodynamic fluid model has been adopted for the description of the dusty plasma medium. For weak non-linear response, analytic reductive perturbative approach has been adopted. It is well known that in the weak coupling regime for the dusty plasma medium, such an analysis leads to the Korteweg-de Vries equation (KdV) equation and predicts the existence of localized smooth soliton solutions. We show that the strongly coupled dust fluid with the correct Galilean invariant form does not follow the KdV paradigm. Instead, it reduces to the form of Hunter-Saxton equation, which does not permit soliton solutions. The system in this case displays singular response with both conservative as well as dissipative attributes. At arbitrary high amplitudes, the existence and spontaneous formation of sharply peaked cusp structures in both weak and strong coupling regimes has been demonstrated numerically.
Dust-ion acoustic cnoidal waves and associated nonlinear ion flux in a nonthermal dusty plasma
Ur-Rehman, Hafeez; Mahmood, S.
2016-09-01
The dust-ion acoustic nonlinear periodic (cnoidal) waves and solitons are investigated in a dusty plasma containing dynamic cold ions, superthermal kappa distributed electrons and static charged dust particles. The massive dust particles can have positive or negative charge depending on the plasma environment. Using reductive perturbation method (RPM) with appropriate periodic boundary conditions, the evolution equations for the first and second order nonlinear potentials are derived. The first order potential is determined through Korteweg-de Vries (KdV) equation which gives dust-ion acoustic cnoidal waves and solitons structures. The solution of second order nonlinear potential is obtained through an inhomogeneous differential equation derived from collecting higher order terms of dynamic equations, which is linear for second order electrostatic potential. The nonlinear ion flux associated with the cnoidal waves is also found out numerically. The numerical plots of the dust-ion acoustic cnoidal wave and soliton structures for both positively and negatively charged dust particles cases and nonthermal electrons are also presented for illustration. It is found that only compressive nonlinear electrostatic structures are formed in case of positively dust charged particles while both compressive and rarefactive nonlinear structures are obtained in case of negatively charged particles depending on the negatively charged dust density in a nonthermal dusty plasma. The numerical results are obtained using data of the ionospheric region containing dusty plasma exist in the literature.
First observation of ELM pacing with vertical jogs in a spherical torus
Energy Technology Data Exchange (ETDEWEB)
Gerhardt, S.P. [Princeton Plasma Physics Laboratory (PPPL); Ahn, Joon-Wook [Oak Ridge National Laboratory (ORNL); Canik, John [ORNL; Maingi, R. [Oak Ridge National Laboratory (ORNL); Bell, R. [Princeton Plasma Physics Laboratory (PPPL); Gates, D. [Princeton Plasma Physics Laboratory (PPPL); Goldston, R. [Princeton Plasma Physics Laboratory (PPPL); Hawryluk, R. [Princeton Plasma Physics Laboratory (PPPL); Le Blanc, B. P. [Princeton Plasma Physics Laboratory (PPPL); Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Sontag, Aaron C [ORNL; Sabbagh, S. A. [Columbia University; Tritz, K. [Johns Hopkins University
2010-01-01
Experiments in a number of conventional aspect ratio tokamaks have been successful in pacing edge localized modes (ELMs) by rapid vertical jogging of the plasma. This paper demonstrates the first pacing of ELMs in a spherical torus plasma. Applied 30 Hz vertical jogs synchronized the ELMs with the upward motion of the plasma. 45 Hz jogs also lead to an increase in the ELM frequency, though the synchronization of the ELMs and jogs was unclear. A reduction in the ELM energy was observed at the higher driven ELM frequencies.
First observation of ELM pacing with vertical jogs in a spherical torus
Gerhardt, S. P.; Ahn, J.-W.; Canik, J. M.; Maingi, R.; Bell, R.; Gates, D.; Goldston, R.; Hawryluk, R.; Le Blanc, B. P.; Menard, J.; Sontag, A. C.; Sabbagh, S.; Tritz, K.
2010-06-01
Experiments in a number of conventional aspect ratio tokamaks have been successful in pacing edge localized modes (ELMs) by rapid vertical jogging of the plasma. This paper demonstrates the first pacing of ELMs in a spherical torus plasma. Applied 30 Hz vertical jogs synchronized the ELMs with the upward motion of the plasma. 45 Hz jogs also lead to an increase in the ELM frequency, though the synchronization of the ELMs and jogs was unclear. A reduction in the ELM energy was observed at the higher driven ELM frequencies.
Análise da máquina Torus sob frenagem eletrodinâmica
Jonas Obert Martins Osório
2011-01-01
Este trabalho foi desenvolvido com o objetivo de estudar a aplicação, para sistema de frenagem veicular, de uma máquina elétrica sem escovas, de armadura toroidal, e fluxo magnético axial produzido por ímãs permanentes de terras raras, a chamada máquina Torus. A máquina foi construída no LMEAE e estudada inicialmente como motor em outro trabalho. Mas, para que se possa avaliar seu funcionamento em sistema de frenagem, o foco é do ponto de vista da máquina como gerador. São realizados testes d...
The non-Maxwellian energy distribution of ions in the warm Io torus
Richardson, J. D.; Siscoe, G. L.
1983-01-01
Observations of Io's torus indicate that the majority of ions have energies of 55-75 eV, with a high-energy tail extending up to the corotation energy. It was found that such a distribution can be established via the Coulomb cooling of ions heated at the corotation energy onto the cold 5-eV electrons. The energy E(asterisk) of the main body of the ions and the shape of the energy distribution are functions of the transport loss time. Matching E(asterisk) with the data (E/asterisk/ = 55-75 eV) requires transport loss times in the range 25-1000 days.
First Observation Of ELM Pacing With Vertical Jogs In A Spherical Torus
Energy Technology Data Exchange (ETDEWEB)
Gerhardt, S P; Canik, J M; Maingi, R; Bell, R; Gates, d; Goldston, R; Hawryluk, R; Le Blanc, B P; Menard, J; Sontag, A C; Sabbagh, S
2010-07-15
Experiments in a number of conventional aspect ratio tokamaks have been successful in pacing edge localized modes (ELMs) by rapid vertical jogging of the plasma. This paper demonstrates the first pacing of ELMs in a spherical torus plasma. Applied 30 Hz vertical jogs synchronized the ELMs with the upward motion of the plasma. 45 Hz jogs also lead to an increase in the ELM frequency, though the synchronization of the ELMs and jogs was unclear. A reduction in the ELM energy was observed at the higher driven ELM frequencies. __________________________________________________
Roth, J. R.; Gerdin, G. A.
1976-01-01
The toroidal ring of plasma contained in the NASA Lewis bumpy-torus superconducting magnet facility may be biased to positive or negative potentials approaching 50 kilovolts by applying direct-current voltages of the respective polarity to 12 or fewer of the midplane electrode rings. The electric fields which are responsible for heating the ions by E/B drift then point radially outward or inward. The low-frequency fluctuations below the ion cyclotron frequency appeared to be dominated by rotating spokes.
Energy Technology Data Exchange (ETDEWEB)
Efthimion, P.C.; Arunasalam, V.; Hosea, J.C.
1979-11-01
Fundamental electron cyclotron resonance damping for 4 mm waves with ordinary polarization is measured for propagation along the major radius traversing the midplane of the plasma in the Princeton Large Torus (PLT). Optical depths obtained from the data are in good agreement with those predicted by the relativistic hot plasma theory. Near blackbody emission over much of the plasma midplane is obtained and, in conjunction with the damping measurements, indicates that the vessel reflectivity is high. The practical use of ordinary mode fundamental electron cyclotron resonance heating (ECRH) in existing and future toroidal devices is supported by these results.
Tangential and Vertical Compact Torus Injection Experiments on the STOR-M Tokamak
Institute of Scientific and Technical Information of China (English)
Xiao Chijin; Liu D.; S. Livingstone; A. K. Singh; E. Zhang; A. Hirose
2005-01-01
This paper describes the setup and results of compact torus (CT) injection experiments on the STOR-M tokamak. Tangential CT injection into STOR-M induced H-mode-like phenomena including doubling the electron density, reduction in the Ha radiation level, suppression of the floating potential fluctuations, suppression of the m = 2 Mirnov oscillations, and increase in the global energy confinement time. Experimental setup, bench-test results, and some preliminary injection data for vertical CT injection experiments on STOR-M will be shown. In addition, numerical simulations of the CT trajectories in tokamak discharges for both tangential and vertical injection geometries will be discussed.
Position-dependent mass approach and quantization for a torus Lagrangian
Yeşiltaş, Özlem
2016-09-01
We have shown that a Lagrangian for a torus surface can yield second-order nonlinear differential equations using the Euler-Lagrange formulation. It is seen that these second-order nonlinear differential equations can be transformed into the nonlinear quadratic and Mathews-Lakshmanan equations using the position-dependent mass approach developed by Mustafa (J. Phys. A: Math. Theor. 48, 225206 (2015)) for the classical systems. Then, we have applied the quantization procedure to the nonlinear quadratic and Mathews-Lakshmanan equations and found their exact solutions.
Structure and deformations of strongly magnetized neutron stars with twisted torus configurations
Ciolfi, R; Gualtieri, L
2010-01-01
We construct general relativistic models of stationary, strongly magnetized neutron stars. The magnetic field configuration, obtained by solving the relativistic Grad-Shafranov equation, is a generalization of the twisted torus model recently proposed in the literature; the stellar deformations induced by the magnetic field are computed by solving the perturbed Einstein's equations; stellar matter is modeled using realistic equations of state. We find that in these configurations the poloidal field dominates over the toroidal field and that, if the magnetic field is sufficiently strong during the first phases of the stellar life, it can produce large deformations.
Energy Technology Data Exchange (ETDEWEB)
Smith, D. R.; Mazzucato, E.; Lee, W.; Park, H. K.; Domier, C. W.; Luhmann, Jr., N. C.
2009-02-13
A collective scattering system has been installed on the National Spherical Torus Experiment (NSTX) to measure electron gyroscale fluctuations in NSTX plasmas. Up to five distinct wavenumbers are measured simultaneously, and the large toroidal curvature of NSTX plasmas provides enhanced spatial localization. Steerable optics can position the scattering volume throughout the plasma from the magnetic axis to the outboard edge. Initial measurements indicate rich turbulent dynamics on the electron gyroscale. The system will be a valuable tool for investigating the connection between electron temperature gradient turbulence and electron thermal transport in NSTX plasmas.
Coincidence Properties for Maps from the Torus to the Klein Bottle
Institute of Scientific and Technical Information of China (English)
Daciberg L. GON(C)ALVES; Michael R. KELLY
2008-01-01
The authors study the coincidence theory for pairs of maps from the Torus to the Klein bottle. Reidemeister classes and the Nielsen number are computed, and it is shown that any given pair of maps satisfies the Wecken property. The 1-parameter Wecken property is studied and a partial negative answer is derived. That is for all pairs of coincidence free maps a countable family of pairs of maps in the homotopy class is constructed such that no two members may be joined by a coincidence free homotopy.
Initial Results from the Lost Alpha Diagnostics on Joint European Torus
Energy Technology Data Exchange (ETDEWEB)
Darrow, Doug; Cecil, Ed; Ellis, Bob; Fullard, Keith; Hill, Ken; Horton, Alan; Kiptily, Vasily; Pedrick, Les; Reich, Matthias
2007-07-25
Two devices have been installed in the Joint European Torus (JET) vacuum vessel near the plasma boundary to investigate the loss of energetic ions and fusion products in general and alpha particles in particular during the upcoming JET experiments. These devices are (i) a set of multichannel thin foil Faraday collectors, and (ii) a well collimated scintillator which is optically connected to a charge-coupled device. Initial results, including the radial energy and poloidal dependence of lost ions from hydrogen and deuterium plasmas during the 2005–06 JET restart campaign, will be presented.
Boyer, Martha L; Barmby, P; Bonanos, A Z; Gehrz, R D; Gordon, K D; Groenewegen, M A T; Lagadec, E; Lennon, D; Marengo, M; McDonald, I; Meixner, M; Skillman, E; Sloan, G C; Sonneborn, G; van Loon, J Th; Zijlstra, A
2014-01-01
The DUSTiNGS survey (DUST in Nearby Galaxies with Spitzer) is a 3.6 and 4.5 micron imaging survey of 50 nearby dwarf galaxies designed to identify dust-producing Asymptotic Giant Branch (AGB) stars and massive stars. Using two epochs, spaced approximately six months apart, we identify a total of 526 dusty variable AGB stars (sometimes called "extreme" or x-AGB stars; [3.6]-[4.5]>0.1 mag). Of these, 111 are in galaxies with [Fe/H] < -1.5 and 12 are in galaxies with [Fe/H] < -2.0, making them the most metal-poor dust-producing AGB stars known. We compare these identifications to those in the literature and find that most are newly discovered large-amplitude variables, with the exception of approximately 30 stars in NGC 185 and NGC 147, one star in IC 1613, and one star in Phoenix. The chemical abundances of the x-AGB variables are unknown, but the low metallicities suggest that they are more likely to be carbon-rich than oxygen-rich and comparisons with existing optical and near-IR photometry confirms tha...
Kiso, Atsushi; Seki, Hirokazu
This paper describes an optimal mapping of the torus self-organizing map for a human forearm motion discrimination on the basis of the myoelectric signals. This study uses the torus self-organizing map (Torus-SOM) for the motion discrimination. The normal SOM identify input data into the same feature group by using the all units of map. Then there is a possibility of the misrecognition motion around the boundary lines of the motion groups. Therefore, this study proposes the mapping method of SOM that the learning units of the same motion concentrate on one local range and the learning unit groups of each motion separates enough. As a result, the variance in the same motion group becomes small and the variance between each motion groups becomes big. Some experiments on the myoelectric hand simulator show the effectiveness of the proposed motion discrimination method.
Detecting the Energy Source in the Hottest Tango in the Universe:. a Torus around a Kerr Black Hole
van Putten, Maurice H. P. M.
2002-09-01
A Kerr black hole surrounded by a a torus is expected to produce emissions in various channels: bursts in baryon poor outflows along the axis of rotation of the black hole and gravitational radiation from the torus, with additional emissions in winds, thermal radiation and, when sufficiently hot, MeV neutrinos. We recently showed that the energy output as a fraction of rotational energy of the black hole is minor in these outflows and major in the emissions from the torus [van Putten & Levinson, Science, 2002, 295, 1874]. The former is proposed as the input to GRBs, consistent with their recently determined true energies. Detection of the energy output Egw in gravitational waves by gravitational wave experiments provides a method for identifying Kerr black holes in events which satisfy 2πEgwfgw > 0.005, where fgw ≃1kHz × (7M⊙/M) denotes the observed gravitational wave frequency.
Repellin, Cécile; Neupert, Titus; Bernevig, B. Andrei; Regnault, Nicolas
2015-09-01
Multilayer fractional quantum Hall wave functions can be used to construct the non-Abelian states of the Zk Read-Rezayi series upon symmetrization over the layer index. Unfortunately, this construction does not yield the complete set of Zk ground states on the torus. We develop an alternative projective construction of Zk Read-Rezayi states that complements the existing one. On the multilayer torus geometry, our construction consists of introducing twisted boundary conditions connecting the layers before performing the symmetrization. We give a comprehensive account of this construction for bosonic states, and numerically show that the full ground state and quasihole manifolds are recovered for all computationally accessible system sizes. Furthermore, we analyze the neutral excitation modes above the Moore-Read on the torus through an extensive exact diagonalization study. We show numerically that our construction can be used to obtain excellent approximations to these modes. Finally, we extend our symmetrization scheme to the plane and sphere geometries.
KOI-2700b—a planet candidate with dusty effluents on a 22 hr orbit
Energy Technology Data Exchange (ETDEWEB)
Rappaport, Saul; Sanchis-Ojeda, Roberto [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Barclay, Thomas; Still, Martin [BAER Institute/NASA Ames Research Center, M/S 244-30, Moffett Field, Mountain View, CA 94035 (United States); DeVore, John [Visidyne, Inc., 111 South Bedford St., Suite 103, Burlington, MA 01803 (United States); Rowe, Jason, E-mail: sar@mit.edu, E-mail: rsanchis86@gmail.com, E-mail: thomas.barclay@nasa.gov, E-mail: martin.d.still@nasa.gov, E-mail: devore@visidyne.com, E-mail: jasonfrowe@gmail.com [SETI Institute, 189 Bernardo Ave, Suite 100 Mountain View, CA 94043 (United States)
2014-03-20
Kepler planet candidate KOI-2700b (KIC 8639908b), with an orbital period of 21.84 hr, exhibits a distinctly asymmetric transit profile, likely indicative of the emission of dusty effluents, and reminiscent of KIC 1255b. The host star has T {sub eff} = 4435 K, M ≅ 0.63 M {sub ☉}, and R ≅ 0.57 R {sub ☉}, comparable to the parameters ascribed to KIC 12557548. The transit egress can be followed for ∼25% of the orbital period and, if interpreted as extinction from a dusty comet-like tail, indicates a long lifetime for the dust grains of more than a day. We present a semiphysical model for the dust tail attenuation and fit for the physical parameters contained in that expression. The transit is not sufficiently deep to allow for a study of the transit-to-transit variations, as is the case for KIC 1255b; however, it is clear that the transit depth is slowly monotonically decreasing by a factor of ∼2 over the duration of the Kepler mission. We infer a mass-loss rate in dust from the planet of ∼2 lunar masses per Gyr. The existence of a second star hosting a planet with a dusty comet-like tail would help to show that such objects may be more common and less exotic than originally thought. According to current models, only quite small planets with M{sub p} ≲ 0.03 M {sub ⊕} are likely to release a detectable quantity of dust. Thus, any 'normal-looking' transit that is inferred to arise from a rocky planet of radius greater than ∼1/2 R {sub ⊕} should not exhibit any hint of a dusty tail. Conversely, if one detects an asymmetric transit due to a dusty tail, then it will be very difficult to detect the hard body of the planet within the transit because, by necessity, the planet must be quite small (i.e., ≲ 0.3 R {sub ⊕}).
Nuclear obscuration in active galactic nuclei
Almeida, Cristina Ramos; Ricci, Claudio
2017-10-01
The material surrounding accreting supermassive black holes connects the active galactic nucleus with its host galaxy and, besides being responsible for feeding the black hole, provides important information on the feedback that nuclear activity produces on the galaxy. In this Review, we summarize our current understanding of the close environment of accreting supermassive black holes obtained from studies of local active galactic nuclei carried out in the infrared and X-ray regimes. The structure of this circumnuclear material is complex, clumpy and dynamic, and its covering factor depends on the accretion properties of the active galactic nucleus. In the infrared, this obscuring material is a transition zone between the broad- and narrow-line regions, and, at least in some galaxies, it consists of two structures: an equatorial disk/torus and a polar component. In the X-ray regime, the obscuration is produced by multiple absorbers across various spatial scales, mostly associated with the torus and the broad-line region. In the coming decade, the new generation of infrared and X-ray facilities will greatly contribute to our understanding of the structure and physical properties of nuclear obscuration in active galactic nuclei.
Indian Academy of Sciences (India)
S S Kannan; Pranab Sardar
2009-02-01
We give a stratification of the $GIT$ quotient of the Grassmannian $G_{2,n}$ modulo the normaliser of a maximal torus of $SL_n(k)$ with respect to the ample generator of the Picard group of $G_{2,n}$. We also prove that the flag variety $GL_n(k)/B_n$ can be obtained as a $GIT$ quotient of $GL_{n+1}(k)/B_{n+1}$ modulo a maximal torus of $SL_{n+1}(k)$ for a suitable choice of an ample line bundle on $GL_{n+1}(k)/B_{n+1}$.
Directory of Open Access Journals (Sweden)
K. Marubashi
2007-11-01
Full Text Available We identified 17 magnetic clouds (MCs with durations longer than 30 h, surveying the solar wind data obtained by the WIND and ACE spacecraft during 10 years from 1995 through 2004. Then, the magnetic field structures of these 17 MCs were analyzed by the technique of the least-squares fitting to force-free flux rope models. The analysis was made with both the cylinder and torus models when possible, and the results from the two models are compared. The torus model was used in order to approximate the curved portion of the MCs near the flanks of the MC loops. As a result, we classified the 17 MCs into 4 groups. They are (1 5 MC events exhibiting magnetic field rotations through angles substantially larger than 180° which can be interpreted only by the torus model; (2 3 other MC events that can be interpreted only by the torus model as well, though the rotation angles of magnetic fields are less than 180°; (3 3 MC events for which similar geometries are obtained from both the torus and cylinder models; and (4 6 MC events for which the resultant geometries obtained from both models are substantially different from each other, even though the observed magnetic field variations can be interpreted by either of the torus model or the cylinder model. It is concluded that the MC events in the first and second groups correspond to those cases where the spacecraft traversed the MCs near the flanks of the MC loops, the difference between the two being attributed to the difference in distance between the torus axis and the spacecraft trajectory. The MC events in the third group are interpreted as the cases where the spacecraft traversed near the apexes of the MC loops. For the MC events in the fourth group, the real geometry cannot be determined from the model fitting technique alone. Though an attempt was made to determine which model is more plausible for each of the MCs in this group by comparing the characteristics of associated bidirectional electron
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The Fukushima nuclear accident provides valuable lessons for China national nuclear Corp.as it continues to expand its operations AS Japan’s Fukushima nuclear crisis sparks a global debate over nuclear safety,China National Nuclear Corp. (CNNC),the country’s largest nuclear plant operator, comes under the spotlight.
Bisbas, T G; Barlow, M J; Viti, S; Harries, T J; Bell, T; Yates, J A
2015-01-01
The interaction of ionizing and far-ultraviolet radiation with the interstellar medium is of great importance. It results in the formation of regions in which the gas is ionized, beyond which are photodissociation regions (PDRs) in which the gas transitions to its atomic and molecular form. Several numerical codes have been implemented to study these two main phases of the interstellar medium either dynamically or chemically. In this paper we present TORUS-3DPDR, a new self-consistent code for treating the chemistry of three-dimensional photoionization and photodissociation regions. It is an integrated code coupling the two codes TORUS, a hydrodynamics and Monte Carlo radiation transport code, and 3D-PDR, a photodissociation regions code. The new code uses a Monte Carlo radiative transfer scheme to account for the propagation of the ionizing radiation including the diffusive component as well as a ray-tracing scheme based on the HEALPix package in order to account for the escape probability and column density...
The r-process in the neutrino-driven wind from a black-hole torus
Wanajo, Shinya
2011-01-01
We examine r-process nucleosynthesis in the neutrino-driven wind from the thick accretion disk (or "torus") around a black hole. Such systems are expected as emnants of binary neutron star or neutron star -- black hole mergers. We consider a simplified, analytic, time-dependent evolution model of a 3M_sun central black hole surrounded by a neutrino emitting accretion torus with 90km radius, which serves as basis for computing spherically symmetric neutrino-driven wind solutions. We find that ejecta with modest entropies (~30 per nucleon in units of the Boltzmann constant) and moderate expansion timescales (~100ms) dominate in the mass outflow. The mass-integrated nucleosynthetic abundances are in good agreement with the solar system r-process abundance distribution if a minimal value of the electron fraction at the charged-particle freezeout, Ye,min~0.2, is achieved. In the case of Ye,min~0.3, the production of r-elements beyond A~130 does not reach to the third peak but could be still important for an explan...
Topological order and Berry connection for the Maxwell Vacuum on a four-torus
Zhitnitsky, Ariel
2014-01-01
We study novel type of contributions to the partition function of the Maxwell system defined on a small compact manifold such as torus. These new terms can not be described in terms of the physical propagating photons with two transverse polarizations. Rather, these novel contributions emerge as a result of tunnelling events when transitions occur between topologically different but physically identical vacuum winding states. These new terms give an extra contribution to the Casimir pressure. The infrared physics in the system can be described in terms of the topological auxiliary non-propagating fields $a_i(\\mathbf{k})$ governed by Chern-Simons -like action. The system can be studied in terms of these auxiliary fields precisely in the same way as a topological insulator can be analyzed in terms of Berry's connection ${\\cal{A}}_i(\\mathbf{k})$. We also argue that the Maxwell vacuum defined on a small 4-torus behaves very much in the same way as a topological insulator with $\\theta\
Integrable Magnetic Geodesic Flows on 2-Torus: New Examples via Quasi-Linear System of PDEs
Agapov, S. V.; Bialy, M.; Mironov, A. E.
2017-05-01
For a magnetic geodesic flow on the 2-torus the only known integrable example is that of a flow integrable for all energy levels. It has an integral linear in momenta and corresponds to a one parameter group preserving the Lagrangian function of the magnetic flow. In this paper the problem of integrability on a single energy level is considered. Then, in addition to the example mentioned above, a few other explicit examples with quadratic in momenta integrals can be constructed by means of the Maupertuis' principle. Recently we proved that such an integrability problem can be reduced to a remarkable semi-Hamiltonian system of quasi-linear PDEs and to the question of the existence of smooth periodic solutions for this system. Our main result of the present paper states that any Liouville metric with the zero magnetic field on the 2-torus can be analytically deformed to a Riemannian metric with a small magnetic field so that the magnetic geodesic flow on an energy level is integrable by means of an integral quadratic in momenta.
Integrable Magnetic Geodesic Flows on 2-Torus: New Examples via Quasi-Linear System of PDEs
Agapov, S. V.; Bialy, M.; Mironov, A. E.
2017-01-01
For a magnetic geodesic flow on the 2-torus the only known integrable example is that of a flow integrable for all energy levels. It has an integral linear in momenta and corresponds to a one parameter group preserving the Lagrangian function of the magnetic flow. In this paper the problem of integrability on a single energy level is considered. Then, in addition to the example mentioned above, a few other explicit examples with quadratic in momenta integrals can be constructed by means of the Maupertuis' principle. Recently we proved that such an integrability problem can be reduced to a remarkable semi-Hamiltonian system of quasi-linear PDEs and to the question of the existence of smooth periodic solutions for this system. Our main result of the present paper states that any Liouville metric with the zero magnetic field on the 2-torus can be analytically deformed to a Riemannian metric with a small magnetic field so that the magnetic geodesic flow on an energy level is integrable by means of an integral quadratic in momenta.
Revisiting the Infrared Spectra of Active Galactic Nuclei with a New Torus Emission Model
Fritz, J; Hatziminaoglou, E
2006-01-01
We describe improved modelling of the emission by dust in a toroidal--like structure heated by a central illuminating source within Active Galactic Nuclei (AGN). We chose a simple but realistic torus geometry, a flared disc, and a dust grain distribution function including a full range of grain sizes. The optical depth within the torus is computed in detail taking into account the different sublimation temperatures of the silicate and graphite grains, which solves previously reported inconsistencies in the silicate emission feature in type-1 AGN. We exploit this model to study the spectral energy distributions (SEDs) of 58 extragalactic (both type-1 and type-2) sources using archival optical and infrared (IR) data. We find that both AGN and starburst contributions are often required to reproduce the observed SEDs, although in a few cases they are very well fitted by a pure AGN component. The AGN contribution to the far-IR luminosity is found to be higher in type-1 sources, with all the type-2 requiring a subs...
X-Ray Probes of Jupiter's Auroral Zones, Galilean Moons, and the Io Plasma Torus
Elsner, R. F.; Ramsey, B. D.; Swartz, D. A.; Rehak, P.; Waite, J. H., Jr.; Cooper, J. F.; Johnson, R. E.
2005-01-01
Remote observations from the Earth orbiting Chandra X-ray Observatory and the XMM-Newton Observatory have shown the the Jovian system is a rich and complex source of x-ray emission. The planet's auroral zones and its disk are powerful sources of x-ray emission, though with different origins. Chandra observations discovered x-ray emission from the Io plasma torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from the moons is due to bombardment of their surfaces by highly energetic magnetospheric protons, and oxygen and sulfur ions, producing fluorescent x-ray emission lines from the elements in their surfaces against an intense background continuum. Although very faint when observed from Earth orbit, an imaging x-ray spectrometer in orbit around the icy Galilean moons would provide a detail mapping of the elemental composition in their surfaces. Here we review the results of Chandra and XMM-Newton observations of the Jovian system and describe the characteristics of X-MIME, an imaging x-ray spectrometer undergoing study for possible application to future missions to Jupiter such as JIMO. X-MIME has the ultimate goal of providing detailed high-resolution maps of the elemental abundances of the surfaces of Jupiter's icy moons and Io, as well as detailed study of the x-ray mission from the Io plasma torus, Jupiter's auroral zones, and the planetary disk.