Sample records for charged polytropic compact

  1. Two Quantum Polytropic Cycles

    NASA Astrophysics Data System (ADS)

    Arias-Hernández, L. A.; Morales-Serrano, A. F.

    2002-11-01

    In this work we follow the Bender et al paper [1] to study the quantum analogues of the Stirling and Ericsson polytropic cycles. In the context of the classical thermodynamics, the Stirling and Ericsson cycles correspond to reversible heat engines with two isothermal processes joined by two polytropic branches which occur in a device called regenerator. If this device is an ideal one, the efficiency of these cycles is the Carnot efficiency. Here, we introduce the quantum analogues of the Stirling and Ericsson cycles, the first one based on a double square potential well with a finite potential barrier, since in this system the tunnel effect could be the analogue to the regeneration classical process, therefore the isochoric quantum branches would really correspond to an internal energy storage, and the last one with an unknown system where the isobaric quantum processes don't induce changes in its quantum state. With these systems the quantum engines have cycles consisting of polytropic and isothermal quantum processes analogues to the corresponding classical processes. We show that in both cases the quantum cycles have an efficiency given by ?CQM = 1 - EC/EH, which is the same expression for the quantum analogue of the Carnot cycle studied by Bender.

  2. Spherical polytropic balls cannot mimic black holes

    E-print Network

    Hiromi Saida; Atsuhito Fujisawa; Chul-Moon Yoo; Yasusada Nambu

    2015-03-09

    The so-called black hole shadow is a dark region which is expected to appear in a fine image of optical observation of black holes. It is essentially an absorption cross section of black hole, and the boundary of shadow is determined by unstable circular orbits of photons (UCOP). If there exists a compact object possessing UCOP but no black hole horizon, it can provide us with the same shadow image with black holes, and a detection of shadow image cannot be a direct evidence of black hole existence. However, we show that a static spherical polytropic ball of perfect fluid cannot possess UCOP, if the sound speed at centre is subluminal (slower-than-light). This implies that, if the polytrope is a good model of stellar matter in compact objects, a detection of shadow image is regarded as a good evidence of black hole existence. As a by-product, we have found an upper bound of mass-to-radius radio of polytropic ball, $M/R sound speed condition.

  3. Spherical polytropic balls cannot mimic black holes

    E-print Network

    Saida, Hiromi; Yoo, Chul-Moon; Nambu, Yasusada

    2015-01-01

    The so-called black hole shadow is a dark region which is expected to appear in a fine image of optical observation of black holes. It is essentially an absorption cross section of black hole, and the boundary of shadow is determined by unstable circular orbits of photons (UCOP). If there exists a compact object possessing UCOP but no black hole horizon, it can provide us the same shadow image with black holes, and a detection of shadow image cannot be a direct evidence of black hole existence. However, we show that a static spherical polytropic ball of perfect fluid cannot possess UCOP, if the sound speed at centre is subluminal. This implies that, if the polytrope is a good model of stellar matter in compact objects, a detection of shadow image is regarded as a good evidence of black hole existence. As a by-product, we have found an upper bound of mass-to-radius radio of polytropic ball, $M/R < 0.281$.

  4. Charged multiplicity measurement for simulated pp events in the Compact Muon Solenoid (CMS) detector

    E-print Network

    Wilt, Brian A

    2007-01-01

    In this thesis, I studied the effectiveness of a method for measuring the charged multiplicity of proton-proton collisions in the Compact Muon Solenoid (CMS) experiment at LHC energies ... This technique involves counting ...

  5. Conformally flat polytropes for anisotropic matter

    E-print Network

    L. Herrera; A. Di Prisco; W. Barreto; J. Ospino

    2014-11-05

    We analyze in detail conformally flat spherically symmetric fluid distributions, satisfying a polytropic equation of state. Among the two possible families of relativistic polytropes, only one contains models which satisfy all the required physical conditions. The ensuing configurations are necessarily anisotropic and show interesting physical properties. Prospective applications of the presented models to the study of super-Chandrasekhar white dwarfs, are discussed.

  6. Industrial test coking of partially compacted charges by the method of briquetting without a binder

    SciTech Connect

    Olfert, A.I.; Taits, E.M.; Semenov, B.M.; Ruban, N.V.; Pavlov, V.V.; Ivanov, A.I.; Kovaleva, N.A.; Kalika, V.G.

    1981-01-01

    As a result of industrial test investigations on the coking of partially compacted charges by the method of briquetting without a binder it was shown that: (1) It is possible in practice to briquette coal charges without a binder to obtain small briquettes weighing about 7-8 g, with density of 1.14 to 1.15 g/cm/sup 3/, sufficiently strong that these briquettes may be used as a component of a coal charge loaded into coke ovens. (2) There ia an increase in the mechanical strength of the coke by the M40 index by 3% and a decrease in the M10 by 1.2% in the box coking of partially compacted industrial coal charge of the Moscow Coke Gas Plant. (3) There is an increase in the yield of the over 40 mm size class coke (by 5 to 10%) with a corresponding decrease in the yield of the finer size classes) depending on the caking capacity in the box coking of partially compacted charges. (4) It is possible to increase (with partial compaction of the charges) the proportion of Kuznetsk poorly-caking coal in the industrial charge of the Moscow Coke Gas Plant to 50 to 60% in comparison to the present 20%.

  7. Evaluation of surface-potential-based bulk-charge compact MOS transistor model

    Microsoft Academic Search

    Bin B. Jie; Chih-Tang Sah

    2005-01-01

    The existing surface-potential-based compact metal-oxide-semiconductor transistor models are based on the 1978 Brews delta-function charge-sheet approximation, which was derived empirically from the 1966 Pao-Sah drift-diffusion double integral formula. This paper provides a device physics-based derivation of a surface-potential-based compact model by analytical approximation of the double and single bulk-charge integrals of the four one-dimensional components of the six-component 1996 Sah

  8. Low power, compact charge coupled device signal processing system

    NASA Technical Reports Server (NTRS)

    Bosshart, P. W.; Buss, D. D.; Eversole, W. L.; Hewes, C. R.; Mayer, D. J.

    1980-01-01

    A variety of charged coupled devices (CCDs) for performing programmable correlation for preprocessing environmental sensor data preparatory to its transmission to the ground were developed. A total of two separate ICs were developed and a third was evaluated. The first IC was a CCD chirp z transform IC capable of performing a 32 point DFT at frequencies to 1 MHz. All on chip circuitry operated as designed with the exception of the limited dynamic range caused by a fixed pattern noise due to interactions between the digital and analog circuits. The second IC developed was a 64 stage CCD analog/analog correlator for performing time domain correlation. Multiplier errors were found to be less than 1 percent at designed signal levels and less than 0.3 percent at the measured smaller levels. A prototype IC for performing time domain correlation was also evaluated.

  9. Equilibrium sequences of irrotational binary polytropic stars : The case of double polytropic stars

    E-print Network

    Keisuke Taniguchi; Takashi Nakamura

    2000-04-03

    Solutions to equilibrium sequences of irrotational binary polytropic stars in Newtonian gravity are expanded in a power of $\\epsilon=a_0/R$, where R and $a_0$ are the orbital separation of the binary system and the radius of each star for $R=\\infty$. For each order of $\\epsilon$, we should solve ordinary differential equations for arbitrary polytropic indices n. We show solutions for polytropic indices n= 0.5, 1, 1.5 and 2 up to $\\epsilon^6$ orders. Our semi-analytic solutions can be used to check the validity of numerical solutions.

  10. On The Way To Off-equatorial Charged Discs Near Compact Objects - Single Test Particles Approximation

    NASA Astrophysics Data System (ADS)

    Kovar, Jiri; Kopacek, O.; Karas, V.; Stuchlik, Z.

    2010-02-01

    We present our recent studies of charged particles motion out of the equatorial plane in strong gravitational and electromagnetic fields. Within the general relativistic approach, we have demonstrated that the interplay between gravitational and electromagnetic action may allow for stable off-equatorial circular motion along the so-called halo orbits near compact objects, such as rotating magnetic compact stars and Kerr black holes immersed in an asymptotically uniform magnetic field of external origin. Locations of halo orbits correspond to minima of the two-dimensional effective potential, which exhibits several qualitativelly different kinds of behaviour, reflecting the charge of moving particles and orientation of the motion. Along with the study of the halo motion itself, we have discussed the general motion in the related off-equatorial potential lobes, demonstrating its chaoticness or regularity in terms of the Poincaré surfaces of sections and recurrence plots. A possible outlook of this study is to build a single test particles model of putative circumpulsar discs consisting of charged dust particles. Institute of Physics and Astronomical Institute have been operated under the projects MSM 4781305903 and AV 0Z10030501, and further supported by the Centre for Theoretical Astrophysics LC06014 in the Czech Republic. JK, VK and ZS thank the Czech Science Foundation (ref. P209/10/P190, 205/07/0052, 202/09/0772). OK acknowledges the doctoral student program of the Czech Science Foundation (205/09/H033).

  11. Rotational properties of composite polytrope models

    SciTech Connect

    Rucinski, S.M.

    1988-06-01

    Factional radii of gyration for both the convective envelope and the radiative core have been determined using the composite-polytrope model of Rappaport et al. (1983) which describes low-mass stars by appropriately matched polytropes n(outer) = 3/2 and n(inner) = 3. Radii of gyration computed for ZAMS stars with masses of 0.4-1.2 solar masses are used to obtain ZAMS angular momenta for low-mass rapidly rotating stars in the Pleiades and Alpha Persei clusters. Results indicate that there is little chance of observing single young early G and late F type stars in rapid rotation because of the very short timescales for braking of their thin convective envelopes. 41 references.

  12. Binary fission in damped rotating polytropes. II

    Microsoft Academic Search

    R. A. Gingold; J. J. Monaghan

    1979-01-01

    The fission sequences of Gingold and Monaghan are recomputed using a significantly larger number (800) of particles in the smoothed-particle-hydrodynamic treatment. The results confirm the general mode of fission found earlier for polytropes with n = 0.5. An interesting three-pointed 'star fish' structure is now apparent before fission and a low-mass third object is formed. The nature of the disruption

  13. Charges and Fluxes in Maxwell Theory on Compact Manifolds with Boundary

    NASA Astrophysics Data System (ADS)

    Alvarez, Marcos; Olive, David I.

    2006-10-01

    We investigate the charges and fluxes that can occur in higher-order Abelian gauge theories defined on compact space-time manifolds with boundary. The boundary is necessary to supply a destination to the electric lines of force emanating from brane sources, thus allowing non-zero net electric charges, but it also introduces new types of electric and magnetic flux. The resulting structure of currents, charges, and fluxes is studied and expressed in the language of relative homology and de Rham cohomology and the corresponding abelian groups. These can be organised in terms of a pair of exact sequences related by the Poincaré-Lefschetz isomorphism and by a weaker flip symmetry exchanging the ends of the sequences. It is shown how all this structure is brought into play by the imposition of the appropriately generalised Maxwell’s equations. The requirement that these equations be integrable restricts the world-volume of a permitted brane (assumed closed) to be homologous to a cycle on the boundary of space-time. All electric charges and magnetic fluxes are quantised and satisfy the Dirac quantisation condition. But through some boundary cycles there may be unquantised electric fluxes associated with quantised magnetic fluxes and so dyonic in nature.

  14. Universal Charge-Radius Relation for Subatomic and Astrophysical Compact Objects

    SciTech Connect

    Madsen, Jes [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

    2008-04-18

    Electron-positron pair creation in supercritical electric fields limits the net charge of any static, spherical object, such as superheavy nuclei, strangelets, and Q balls, or compact stars like neutron stars, quark stars, and black holes. For radii between 4x10{sup 2} and 10{sup 4} fm the upper bound on the net charge is given by the universal relation Z=0.71R{sub fm}, and for larger radii (measured in femtometers or kilometers) Z=7x10{sup -5}R{sub fm}{sup 2}=7x10{sup 31}R{sub km}{sup 2}. For objects with nuclear density the relation corresponds to Z{approx_equal}0.7A{sup 1/3} (10{sup 8}10{sup 12}), where A is the baryon number. For some systems this universal upper bound improves existing charge limits in the literature.

  15. Fast-charging compact seed source for magnetic flux compression generators.

    PubMed

    Elsayed, M; Kristiansen, M; Neuber, A

    2008-12-01

    Flux compression generators (FCGs) are some of the most attractive sources of single-use compact pulsed power available today due to their high energy density output and mobility. Driving FCGs requires some seed energy, which is typically provided by applying a high seed current, usually in the kiloampere range for midsized helical FCGs. This initial current is supplied by a high-current seed source that is capable of driving an inductive load. High-current seed sources have typically been comprised of discharging large capacitors using spark gaps and overvoltage triggering mechanisms to provide the prime power for FCGs. This paper will discuss a recent design of a self-contained (battery powered with full charge time less than 40 s), single-use compact seed source (CSS) using solid-state components for the switching scheme. The CSS developed is a system (0.005 m(3) volume and weighing 3.9 kg) capable of delivering over 360 J ( approximately 12 kA) into a 5.20 muH load with a trigger energy of microjoules at the TTL triggering level. The newly designed solid-state switching scheme of the CSS incorporates off-the-shelf high-voltage semiconductor components that minimize system cost and size as necessary for a single-use application. A detailed evaluation of the CSS is presented primarily focusing on the switching mechanics and experimental characterization of the solid-state components used in the system. PMID:19123584

  16. Fast-charging compact seed source for magnetic flux compression generators

    NASA Astrophysics Data System (ADS)

    Elsayed, M.; Kristiansen, M.; Neuber, A.

    2008-12-01

    Flux compression generators (FCGs) are some of the most attractive sources of single-use compact pulsed power available today due to their high energy density output and mobility. Driving FCGs requires some seed energy, which is typically provided by applying a high seed current, usually in the kiloampere range for midsized helical FCGs. This initial current is supplied by a high-current seed source that is capable of driving an inductive load. High-current seed sources have typically been comprised of discharging large capacitors using spark gaps and overvoltage triggering mechanisms to provide the prime power for FCGs. This paper will discuss a recent design of a self-contained (battery powered with full charge time less than 40 s), single-use compact seed source (CSS) using solid-state components for the switching scheme. The CSS developed is a system (0.005 m3 volume and weighing 3.9 kg) capable of delivering over 360 J (˜12 kA) into a 5.20 ?H load with a trigger energy of microjoules at the TTL triggering level. The newly designed solid-state switching scheme of the CSS incorporates off-the-shelf high-voltage semiconductor components that minimize system cost and size as necessary for a single-use application. A detailed evaluation of the CSS is presented primarily focusing on the switching mechanics and experimental characterization of the solid-state components used in the system.

  17. General polytropic Larson-Penston-type collapses

    NASA Astrophysics Data System (ADS)

    Lou, Yu-Qing; Shi, Chun-Hui

    2014-12-01

    We investigate self-similar hydrodynamics of a general polytropic (GP) gas with spherical symmetry under self-gravity and extend the conventional polytropic (CP) relation n = 2 - ? for the self-similar index n and the polytropic index ? to a general relation n = 2(q + ? - 2)/(3q - 2), where q is a real parameter by specific entropy conservation along streamlines. We derive GP Larson-Penston (LP)-type solutions for q > 2/3 and ? > 4/3; Larson-Penston-Hunter (LPH)-type solutions are also constructed in a GP gas by a time-reversal operation on a GP-LP-type solution and by connecting to a GP free-fall-type solution across t = 0. These GP-LPH solutions describe dynamic processes that a GP gas globule, static and dense initially, undergoes a runaway collapse under self-gravity, forms a central mass singularity, and keeps accreting during a free-fall stage. We apply such GP-LPH-type solutions with variable envelope mass infall rates (EMIRs) for the dynamic evolution of globules and dense cores in star-forming molecular clouds. In particular, a GP-LPH-type solution can sustain an EMIR as low as 10-8 ˜ 10-6 M? yr-1 or even lower - much lower than that of Shu's isothermal model for a cloud core in Class 0 and Class I phases. Such GP-LPH-type solutions with EMIRs as low as 10-9 ˜ 10-8 M? yr-1 offer a sensible viable mechanism of forming brown dwarfs during the accretion stage in a collapsed GP globules with 1.495 ? ? ? 1.50 and 0.99 ? n ? 1.0. The GP-LPH solutions with 0.94 < n < 0.99 and 1.47 < ? < 1.495 can even give extremely low EMIRs of 10-12 ˜ 10-9 M? yr-1 to form gaseous planet-type objects in mini gas globules.

  18. Compact formulae, dynamics and radiation of charged particles under synchro-curvature losses

    NASA Astrophysics Data System (ADS)

    Viganò, Daniele; Torres, Diego F.; Hirotani, Kouichi; Pessah, Martín E.

    2015-02-01

    We consider the fundamental problem of charged particles moving along and around a curved magnetic field line, revising the synchro-curvature radiation formulae introduced by Cheng & Zhang. We provide more compact expressions to evaluate the spectrum emitted by a single particle, identifying the key parameter that controls the transition between the curvature-dominated and the synchrotron-dominated regime. This parameter depends on the local radius of curvature of the magnetic field line, the gyration radius, and the pitch angle. We numerically solve the equations of motion for the emitting particle by considering self-consistently the radiative losses, and provide the radiated spectrum produced by a particle when an electric acceleration is balanced by its radiative losses, as it is assumed to happen in the outer gaps of pulsar's magnetospheres. We compute the average spectrum radiated throughout the particle trajectory finding that the slope of the spectrum before the peak depends on the location and size of the emission region. We show how this effect could then lead to a variety of synchro-curvature spectra. Our results reinforce the idea that the purely synchrotron or curvature losses are, in general, inadequate to describe the radiative reaction on the particle motion, and the spectrum of emitted photons. Finally, we discuss the applicability of these calculations to different astrophysical scenarios.

  19. Autogravity waves in a polytropic layer

    NASA Astrophysics Data System (ADS)

    Qian, Zhongshan

    The mystery of the spiral arms in galaxies is investigated. Since B. Lindblad, a few theories have come up that partially explain the spiral arms. One theory is due to C. C. Lin and F. H. Shu. They interpret the spiral arms as a density wave. This theory has been partially supported by observations. However it has also generated some criticism. A major weakness of this theory is its dispersiveness. That is, after a long enough time, there will be no localized structure in the system, which is contrary to the observations. The remedy for this defect is to include the nonlinear term that balances the dispersive term. With this in mind, we explore the nonlinear properties of a simple model of galactic slab. The model was originally studied by Ledoux in 1952. We consider here a polytropic gas slab under the influence of both self-gravitational and external potential. Physically, the external force can be thought of as a compound effect of the halo surrounding the whole galaxy. We then study the development of gravitational instability. To get to the nonlinear regime, we choose mild instability; that is to say the control parameters are near the critical point. In the long wavelength limit, we found that the waves obey the nonlinear evolution equations similar to the Bousinesq and K.d.V. equations if we choose the appropriate scalings. On the other hand, if we choose the scalings similar to the shallow water theory, the equations will be modified shallow water equations in a projected dimension. The possibility of some nonlinear solutions is also discussed.

  20. Charged particle driver for ICF using an accelerated, focused compact torus

    SciTech Connect

    Meeker, D.J.; Hammer, J.H.; Hartman, C.W.

    1986-06-01

    We report the status of evaluating an accelerated and focused compact torus as a driver for ICF. We are studying the acceleration and focusing aspects experimentally in the RACE facility, a recently completed ring generator coupled to a 260 kJ acceleration bank. Compact torus and ICF target interaction is being investigated with PIC codes and LASNEX, a 2D magneto-hydrodynamics code. Final conditions required of the CT are discussed as well as coupling issues such as superthermal electron production. We conclude with an economic evaluation of a few 100 MW reactor driven by a compact torus. 9 refs., 5 figs., 1 tab.

  1. Polytropic and Chaplygin f(R)-gravity models

    E-print Network

    K. Karami; M. S. Khaledian

    2012-12-12

    We reconstruct different f(R)-gravity models corresponding to the polytropic, standard Chaplygin, generalized Chaplygin, modified Chaplygin and modified variable Chaplygin gas dark energy models. We also obtain the equation of state parameters of the corresponding f(R)-gravity models which describe the accelerated expansion of the universe. We conclude that although the equation of state parameters of the obtained f(R)-gravities can behave like phantom or quintessence dark energy models, they cannot justify the transition from the quintessence state to the phantom regime. Furthermore, the polytropic and Chaplygin f(R)-gravity models in de Sitter space can satisfy the inflation condition.

  2. Development of a Compact Switched-Reluctance Motor Drive for EV Propulsion With Voltage-Boosting and PFC Charging Capabilities

    Microsoft Academic Search

    Hung-Chun Chang; Chang-Ming Liaw

    2009-01-01

    This paper presents a compact battery-powered switched-reluctance motor (SRM) drive for an electric vehicle with voltage-boosting and on-board power-factor-corrected-charging capabilities. Although the boost-type front-end DC\\/DC converter is externally equipped, the on-board charger is formed by the embedded components of SRM windings and converter. In the driving mode, the DC\\/DC boost converter is controlled to establish boostable well-regulated DC-link voltage for

  3. Demonstration of charge breeding in a compact room temperature electron beam ion trap

    SciTech Connect

    Vorobjev, G.; Sokolov, A.; Herfurth, F.; Kester, O.; Quint, W.; Stoehlker, Th. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt (Germany); Thorn, A.; Zschornack, G. [Fachrichtung Physik, Technische Universitaet Dresden, Helmholtzstrasse 10, 01069 Dresden (Germany)

    2012-05-15

    For the first time, a small room-temperature electron beam ion trap (EBIT), operated with permanent magnets, was successfully used for charge breeding experiments. The relatively low magnetic field of this EBIT does not contribute to the capture of the ions; single-charged ions are only caught by the space charge potential of the electron beam. An over-barrier injection method was used to fill the EBIT's electrostatic trap with externally produced, single-charged potassium ions. Charge states as high as K{sup 19+} were reached after about a 3 s breeding time. The capture and breeding efficiencies up to 0.016(4)% for K{sup 17+} have been measured.

  4. Linear and nonlinear dynamic instability of rotating polytropes

    NASA Technical Reports Server (NTRS)

    Williams, Harold A.; Tohline, Joel E.

    1987-01-01

    A three-dimensional hydrodynamic computer program is used to study the growth of nonaxisymmetric structures in rapidly rotating, self-gravitating polytropes. Models with polytropic index n = 0.8, 1.0, 1.3, 1.5, and 1.8 are studied. The initially axisymmetric equilibria are constructed by the Ostriker-Mark self-consistent-field method. The nonaxisymmetric pattern that develops out of low-amplitude random noise is a two-armed spiral with a well-defined pattern speed and growth rate which closely match properties of the toroidal mode predicted from the linear, second-order tensor-virial equation. A Fourier analysis of each polytrope's azimuthal density distribution shows that, even in the linear amplitude regime, higher-order angular patterns also develop exponentially in time. The higher-order patterns ultimately move in synchronization with the broad two-armed spiral, creating a narrow two-armed spiral. As the polytropic index is decreased, a more open and centrally more barlike pattern develops.

  5. Numerical Modeling of Tidal Effects in Polytropic Accretion Discs

    NASA Technical Reports Server (NTRS)

    Godon, P.

    1996-01-01

    A two-dimensional time-dependent hybrid Fourier-Chebyshev method of collocation is developed and used for the study of tidal effects in accretion discs, under the assumption of a polytropic equation of state and a standard alpha viscosity prescription.

  6. Symmetry Reduction of Lane-Emden Equation for Polytropes

    E-print Network

    Babur M. Mirza

    2008-07-03

    We describe an ansatz for symmetry reduction of the Lane-Emden equation for an arbitrary polytropic index n, admitting only one symmetry generator. For the reduced first order differential equation it is found that standard reduction procedure do not admit any non-trivial Lie point symmetry. However some special solutions for the differential equation are obtained.

  7. Is scalar-tensor gravity consistent with polytropic stellar models?

    E-print Network

    Kaisa Henttunen; Iiro Vilja

    2015-03-01

    We study the scalar field potential $V(\\phi)$ in the scalar-tensor gravity with self-consistent polytropic stellar configurations. Without choosing a particular potential, we numerically derive the potential inside various stellar objects. We restrict the potential to conform to general relativity or to $f(R)$ gravity inside and require the solution to arrive at SdS vacuum at the surface. The studied objects are required to obtain observationally valid masses and radii corresponding to solar type stars, white dwarfs and neutron stars. We find that the resulting scalar-tensor potential $V(\\phi)$ for the numerically derived polytrope that conforms to general relativity, in each object class, is highly dependent on the matter configuration as well as on the vacuum requirement at the boundary. As a result, every stellar configuration arrives at a potential $V(\\phi)$ that is not consistent with the other stellar class potentials. Therefore, a general potential that conforms to all these polytropic stellar classes could not be found.

  8. Caloric curves fitted by polytropic distributions in the HMF model

    NASA Astrophysics Data System (ADS)

    Campa, Alessandro; Chavanis, Pierre-Henri

    2013-04-01

    We perform direct numerical simulations of the Hamiltonian mean field (HMF) model starting from non-magnetized initial conditions with a velocity distribution that is (i) Gaussian; (ii) semi-elliptical, and (iii) waterbag. Below a critical energy E c , depending on the initial condition, this distribution is Vlasov dynamically unstable. The system undergoes a process of violent relaxation and quickly reaches a quasi-stationary state (QSS). We find that the distribution function of this QSS can be conveniently fitted by a polytrope with index (i) n = 2; (ii) n = 1; and (iii) n = 1/2. Using the values of these indices, we are able to determine the physical caloric curve T kin ( E) and explain the negative kinetic specific heat region C kin = dE/ d T kin < 0 observed in the numerical simulations. At low energies, we find that the system has a "core-halo" structure. The core corresponds to the pure polytrope discussed above but it is now surrounded by a halo of particles. In case (iii), we recover the "uniform" core-halo structure previously found by Pakter and Levin [Phys. Rev. Lett. 106, 200603 (2011)]. We also consider unsteady initial conditions with magnetization M 0 = 1 and isotropic waterbag velocity distribution and report the complex dynamics of the system creating phase space holes and dense filaments. We show that the kinetic caloric curve is approximately constant, corresponding to a polytrope with index n 0 ? 3.56 (we also mention the presence of an unexpected hump). Finally, we consider the collisional evolution of an initially Vlasov stable distribution, and show that the time-evolving distribution function f( ?,v,t) can be fitted by a sequence of polytropic distributions with a time-dependent index n( t) both in the non-magnetized and magnetized regimes. These numerical results show that polytropic distributions (also called Tsallis distributions) provide in many cases a good fit of the QSSs. They may even be the rule rather than the exception. However, in order to moderate our message, we also report a case where the Lynden-Bell theory (which assumes ergodicity or efficient mixing) provides an excellent prediction of an inhomogeneous QSS. We therefore conclude that both Lynden-Bell and Tsallis distributions may be useful to describe QSSs depending on the efficiency of mixing.

  9. Design of a compact electron cyclotron resonance ion source for medium charge state light ions

    SciTech Connect

    Button, D.; Hotchkis, M. A. C. [Australian Nuclear Science and Technology Organization, Sydney, NSW 2234 (Australia); Milford, G. N. [University of New South Wales, Canberra, ACT 2600 (Australia)

    2012-02-15

    At the Australian Nuclear Science and Technology Organization we are developing a new isotope ratio mass spectrometer based on the measurement of multiple charge state ions. We have carried out a review of our existing ECR ion source and identified a number of design flaws. For the new instrument, we are producing a new ECR source and have refined the design, in particular by using 3D simulations to improve the magnetic confinement field and by a combination of simulations and experiments to improve the design of the microwave coupling.

  10. Neutron sources for BNCT using low-power research reactors or compact charged particle accelerators

    NASA Astrophysics Data System (ADS)

    Harker, Yale D.; Nigg, David W.; Mitchell, Hannah E.; Wheeler, Floyd J.; Jones, James L.

    1997-02-01

    Since 1986, the Idaho National Engineering Laboratory (INEL) has been involved in the development of epithermal neutron sources for BNCT. The INEL effort was instrumental in the implementation of an epithermal neutron beam at the Brookhaven Medical Research Reactor at Brookhaven National Laboratory. Recently, the INEL's effort has been directed toward developing advanced filter designs for use with low- power research reactors such as the 250W and 1MW class TRIGA reactors which are located at various sites and universities throughout the world. This work has focused on utilizing advanced filter materials that more effectively reduce fast neutron contamination in the epithermal neutron beam and at the same time optimize neutron economy. The INEL has also been involved in developing two concepts of producing neutron sources for BNCT using charged particle accelerators. The first concept involves the use of an electron accelerator/photoneutron source. The second concept involves the use of a charged particle beam in which the particle energy is just above the threshold energy of the reaction. This paper will review the progress made by INEL in modifying the WSU TRIGA reactor and conceptual development of an electron accelerator based photoneutron source for BNCT. The near threshold particle accelerator development will be discussed in a separate paper.

  11. Kelvin-Helmholtz instability of anisotropic magnetized plasma using generalized polytrope laws

    Microsoft Academic Search

    R. P. Prajapati; R. K. Chhajlani; A. K. Parihar

    2010-01-01

    The problem of Kelvin-Helmholtz (K-H) instability of two superposed compressible magnetized anisotropic pressure plasmas is investigated using generalized polytrope laws. The relevant magnetohydrodynamic (MHD) equations of the problem have been modified using generalized polytrope laws in terms of polytropic indices. The general dispersion relation is obtained using normal mode analysis by applying the appropriate boundary conditions. The conditions for K-H

  12. Self-similar dynamics of polytropic gaseous spheres

    NASA Technical Reports Server (NTRS)

    Suto, Yasushi; Silk, Joseph

    1988-01-01

    The fundamental equations governing the self-similar dynamics of 'polytropic' gaseous spheres are derived, and the asymptotic solutions are given. The solutions divide into cases with and without 'critical points' in closed analogy with the solar wind solutions of Holzer and Axford (1970). Properties for solutions with critical points are discussed, and their behavior around the critical point is derived explicitly for n = 1. Numerical examples of self-similar solutions for n = 1 and n = 2 - gamma are presented, and the properties of the solutions are discussed.

  13. Superfluid hydrodynamics of polytropic gases: dimensional reduction and sound velocity

    NASA Astrophysics Data System (ADS)

    Bellomo, N.; Mazzarella, G.; Salasnich, L.

    2014-03-01

    Motivated by the fact that two-component confined fermionic gases in Bardeen-Cooper-Schrieffer-Bose-Einstein condensate (BCS-BEC) crossover can be described through an hydrodynamical approach, we study these systems—both in the cigar-shaped configuration and in the disc-shaped one—by using a polytropic Lagrangian density. We start from the Popov Lagrangian density and obtain, after a dimensional reduction process, the equations that control the dynamics of such systems. By solving these equations we study the sound velocity as a function of the density by analyzing how the dimensionality affects this velocity.

  14. Can rigidly rotating polytropes be sources of the Kerr metric?

    E-print Network

    J. Martin; A. Molina; E. Ruiz

    2007-09-07

    We use a recent result by Cabezas et al. to build up an approximate solution to the gravitational field created by a rigidly rotating polytrope. We solve the linearized Einstein equations inside and outside the surface of zero pressure including second-order corrections due to rotational motion to get an asymptotically flat metric in a global harmonic coordinate system. We prove that if the metric and their first derivatives are continuous on the matching surface up to this order of approximation, the multipole moments of this metric cannot be fitted to those of the Kerr metric.

  15. Compact multichannel neutral particle analyzer for measurement of energetic charge-exchanged neutrals in Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Tang, V.; Liptac, J.; Parker, R. R.; Bonoli, P. T.; Fiore, C. L.; Granetz, R. S.; Irby, J. H.; Lin, Y.; Wukitch, S. J.; The Alcator C-Mod Team, Frenje, J. A.; Leiter, R.; Mcduffee, S.; Petrasso, R. D.

    2006-08-01

    A four-channel compact neutral particle analyzer (CNPA) based on operating small Si diode detectors in pulse-height analysis (PHA) mode is used to measure energetic hydrogen minority ions with energies between ˜50 and 350keV stemming from ion-cyclotron range-of-frequency heated D(H) Alcator C-Mod plasmas with both active and passive charge exchange (CX). First core minority ion distribution results from Alcator C-Mod discharges and a detailed description of the diagnostic are presented. The diagnostic employs integrated electronics and fast digitization of the shaping amplifier voltage. The digitized data are stored for postshot PHA, which removes the constraints of real-time PHA and allows for improved performance via elimination of base line shift effects and potentially relieving pileup through Gaussian fitting routines. The CNPA is insensitive to the large gamma and neutron background in Alcator C-Mod discharges but is susceptible to the plasma's soft x-ray flux. The soft x-ray flux limits the CNPA energy resolution to ˜15-20keV. A simple model is used to interpret the active CNPA data which permits rapid estimates of the core hydrogen minority temperatures and anisotropy with a time resolution of ˜100ms. Hydrogenlike boron is identified as an important electron donor for the CX signal.

  16. Compact multichannel neutral particle analyzer for measurement of energetic charge-exchanged neutrals in Alcator C-Mod

    SciTech Connect

    Tang, V.; Liptac, J.; Parker, R. R.; Bonoli, P. T.; Fiore, C. L.; Granetz, R. S.; Irby, J. H.; Lin, Y.; Wukitch, S. J.; Frenje, J. A.; Leiter, R.; Mcduffee, S.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2006-08-15

    A four-channel compact neutral particle analyzer (CNPA) based on operating small Si diode detectors in pulse-height analysis (PHA) mode is used to measure energetic hydrogen minority ions with energies between {approx}50 and 350 keV stemming from ion-cyclotron range-of-frequency heated D(H) Alcator C-Mod plasmas with both active and passive charge exchange (CX). First core minority ion distribution results from Alcator C-Mod discharges and a detailed description of the diagnostic are presented. The diagnostic employs integrated electronics and fast digitization of the shaping amplifier voltage. The digitized data are stored for postshot PHA, which removes the constraints of real-time PHA and allows for improved performance via elimination of base line shift effects and potentially relieving pileup through Gaussian fitting routines. The CNPA is insensitive to the large gamma and neutron background in Alcator C-Mod discharges but is susceptible to the plasma's soft x-ray flux. The soft x-ray flux limits the CNPA energy resolution to {approx}15-20 keV. A simple model is used to interpret the active CNPA data which permits rapid estimates of the core hydrogen minority temperatures and anisotropy with a time resolution of {approx}100 ms. Hydrogenlike boron is identified as an important electron donor for the CX signal.

  17. Implementation of polytropic method to study initial structures of gas giant protoplanets

    NASA Astrophysics Data System (ADS)

    Paul, Gour Chandra; Barman, Mrinal Chandra; Mohit, Abdul Al

    2014-12-01

    In this paper we have determined the initial structures of gas giant protoplanets, formed via disk instability, having a mass range of 0.3-10 Jupiter masses by the simple polytropic method. The polytropic protoplanets or polytropes have been assumed to be spheres of solar composition, each of which is in a steady state of quasi-static equilibrium, where the only source of energy is the gravitational contraction of the gas. The results of our calculations for the polytropes with polytropic indices n = 1 and n = 1.5 are found to be closer to reality and are in good agreement with the findings obtained by other investigations with more rigorous treatment of the problem.

  18. Shear instabilities in a fully compressible polytropic atmosphere

    NASA Astrophysics Data System (ADS)

    Witzke, V.; Silvers, L. J.; Favier, B.

    2015-05-01

    Shear flows have a significant impact on the dynamics in an assortment of different astrophysical objects, including accretion discs and stellar interiors. Investigating shear flow instabilities in a polytropic atmosphere provides a fundamental understanding of the motion in stellar interiors where turbulent motions, mixing processes, and magnetic field generation take place. Here, a linear stability analysis for a fully compressible fluid in a two-dimensional Cartesian geometry is carried out. Our study focuses on determining the critical Richardson number for different Mach numbers and the destabilising effects of high thermal diffusion. We find that there is a deviation in the predicted stability threshold for moderate Mach number flows, along with a significant effect on the growth rate of the linear instability for small Péclet numbers. We show that in addition to a Kelvin-Helmholtz instability, a Holmboe instability can appear, and we discuss the implication of this in stellar interiors.

  19. Shear instabilities in a fully compressible polytropic atmosphere

    E-print Network

    Witzke, V; Favier, B

    2015-01-01

    Shear flows have an important impact on the dynamics in an assortment of different astrophysical objects including accreditation discs and stellar interiors. Investigating shear flow instabilities in a polytropic atmosphere provides a fundamental understanding of the motion in stellar interiors where turbulent motions, mixing processes, as well as magnetic field generation takes place. Here, a linear stability analysis for a fully compressible fluid in a two-dimensional Cartesian geometry is carried out. Our study focuses on determining the critical Richardson number for different Mach numbers and the destabilising effects of high thermal diffusion. We find that there is a deviation of the predicted stability threshold for moderate Mach number flows along with a significant effect on the growth rate of the linear instability for small P\\'eclet numbers. We show that in addition to a Kelvin-Helmholtz instability a Holmboe instability can appear and we discuss the implication of this in stellar interiors.

  20. Dynamical 3-Space Gravity Theory: Effects on Polytropic Solar Models

    E-print Network

    Richard D May; Reginald T Cahill

    2010-09-29

    Numerous experiments and observations have confirmed the existence of a dynamical 3-space, detectable directly by light-speed anisotropy experiments, and indirectly by means of novel gravitational effects, such as bore hole g anomalies, predictable black hole masses, flat spiral-galaxy rotation curves, and the expansion of the universe, all without dark matter and dark energy. The dynamics for this 3-space follows from a unique generalisation of Newtonian gravity, once that is cast into a velocity formalism. This new theory of gravity is applied to the sun to compute new density, pressure and temperature profiles, using polytrope modelling of the equation of state for the matter. These results should be applied to a re-analysis of solar neutrino production, and to stellar evolution in general.

  1. A compact charge-based model to study the nanoscale undoped double gate MOSFETs for nanoelectronic circuit design using genetic algorithms

    NASA Astrophysics Data System (ADS)

    Bendib, T.; Djeffal, F.; Arar, D.

    2013-04-01

    The analytical modeling of nanoscale devices is an important area of computer-aided design for fast and accurate nanoelectronic design and optimization. In the present paper, a new approach for modeling semiconductor devices, nanoscale double gate DG MOSFETs, by use of the gradual channel approximation (GC) approach and genetic algorithm optimization technique (GA) is presented. The proposed approach combines the universal optimization and fitting capability of GA and the cost-effective optimization concept of quantum correction, to achieve reliable, accurate and simple compact models for nanoelectronic circuit simulations. Our compact models give good predictions of the quantum capacitance, threshold voltage shift, quantum inversion charge density and drain current. These models have been verified with 2D self-consistent results from numerical calculations of the coupled Poisson-Schrödinger equations. The developed models can also be incorporated into nanoelectronic circuit simulators to study the nanoscale CMOS-based devices without impact on the computational time and data storage.

  2. Receptors for polytropic and xenotropic mouse leukaemia viruses encoded by a single gene at Rmc1

    Microsoft Academic Search

    Yun-Liang Yang; Lei Guo; Shuang Xu; Christine A. Holland; Toshio Kitamura; Kent Hunter; James M. Cunningham

    1999-01-01

    The onset of leukaemia caused by type C retroviruses (MLV) in mice is accelerated by the emergence of recombinant polytropic or mink cell focus–forming (MCF) viruses. Susceptibility to infection by polytropic\\/MCF and also by closely related xenotropic MLV has been mapped to Rmc1 on mouse chromosome 1 (refs 5, 6 and 7). To identify this gene, we introduced an expression

  3. Compact autonomous explosive-driven pulsed power system based on a capacitive energy storage charged by a high-voltage shock-wave ferromagnetic generator

    NASA Astrophysics Data System (ADS)

    Shkuratov, Sergey I.; Talantsev, Evgueni F.; Baird, Jason; Altgilbers, Larry L.; Stults, Allen H.

    2006-06-01

    A new concept for constructing compact autonomous pulsed power systems is presented. This concept utilizes a high-voltage explosive-driven shock-wave ferromagnetic generator (FMG) as a charging source for capacitive energy storage. It has been experimentally demonstrated that miniature FMGs (22-25cm3 in size and 84-95g in mass) developed for these experiments can be successfully used to charge capacitor banks. The FMGs, containing Nd2Fe14B energy-carrying elements, provided pulsed powers of 35-45kW in times ranging from 10to15?s. A methodology was developed for digital simulation of the operation of the transverse FMG. Experimental results that were obtained are in a good agreement with the results of digital simulations.

  4. Critical rotation of general-relativistic polytropic models revisited

    NASA Astrophysics Data System (ADS)

    Geroyannis, V.; Karageorgopoulos, V.

    2013-09-01

    We develop a perturbation method for computing the critical rotational parameter as a function of the equatorial radius of a rigidly rotating polytropic model in the "post-Newtonia approximation" (PNA). We treat our models as "initial value problems" (IVP) of ordinary differential equations in the complex plane. The computations are carried out by the code dcrkf54.f95 (Geroyannis and Valvi 2012 [P1]; modified Runge-Kutta-Fehlberg code of fourth and fifth order for solving initial value problems in the complex plane). Such a complex-plane treatment removes the syndromes appearing in this particular family of IVPs (see e.g. P1, Sec. 3) and allows continuation of the numerical integrations beyond the surface of the star. Thus all the required values of the Lane-Emden function(s) in the post-Newtonian approximation are calculated by interpolation (so avoiding any extrapolation). An interesting point is that, in our computations, we take into account the complete correction due to the gravitational term, and this issue is a remarkable difference compared to the classical PNA. We solve the generalized density as a function of the equatorial radius and find the critical rotational parameter. Our computations are extended to certain other physical characteristics (like mass, angular momentum, rotational kinetic energy, etc). We find that our method yields results comparable with those of other reliable methods. REFERENCE: V.S. Geroyannis and F.N. Valvi 2012, International Journal of Modern Physics C, 23, No 5, 1250038:1-15.

  5. Numerical Modeling of Tidal Effects in Polytropic Accretion Disks

    NASA Technical Reports Server (NTRS)

    Godon, Patrick

    1997-01-01

    A two-dimensional time-dependent hybrid Fourier-Chebyshev method of collocation is developed and used for the study of tidal effects in accretion disks, under the assumptions of a polytropic equation of state and a standard alpha viscosity prescription. Under the influence of the m = 1 azimuthal component of the tidal potential, viscous oscillations in the outer disk excite an m = 1 eccentric instability in the disk. While the m = 2 azimuthal component of the tidal potential excites a Papaloizou-Pringle instability in the inner disk (a saturated m = 2 azimuthal mode), with an elliptic pattern rotating at about a fraction (approx. = 1/3) of the local Keplerian velocity in the inner disk. The period of the elliptic mode corresponds well to the periods of the short-period oscillations observed in cataclysmic variables. In cold disks (r(Omega)/c(sub s) = M approx. = 40) we also find a critical value of the viscosity parameter (alpha approx. = 0.01), below which shock dissipation dominates and is balanced by the wave amplification due to the wave action conservation. In this case the double spiral shock propagates all the way to the inner boundary with a Mach number M(sub s) approx. = 1.3.

  6. Compact Analytic Expression for the Electric Field of a 2DElliptical Charge Distribution Inside a Perfectly Conducting CircularCylinder

    SciTech Connect

    Furman, M.A.

    2007-05-29

    By combining the method of images with calculus of complex variables, we provide a simple expression for the electric field of a two-dimensional (2D) static elliptical charge distribution inside a perfectly conducting cylinder. The charge distribution need not be concentric with the cylinder.

  7. Compact multichannel neutral particle analyzer for measurement of energetic charge-exchanged neutrals in Alcator C-Mod

    E-print Network

    , which removes the constraints of real-time PHA and allows for improved performance via elimination-channel compact neutral particle analyzer CNPA based on operating small Si diode detectors in pulse to measure these fast ion distributions. Here, we present a Si diode- based neutral particle analyzer system

  8. Application of AN Empirically-Derived Polytropic Index for the Solar Wind to a Solar Wind Shock Propagation Model

    Microsoft Academic Search

    Tracy Lynn Totten

    1994-01-01

    Data from the Helios 1 spacecraft have been used to determine an empirical value for the polytropic index for the free-streaming solar wind. Application of this non-adiabatic polytropic index to a two-dimensional solar wind computer model to simulate the effects of thermal heat conduction has been investigated. The current project involves the insertion of this empirically-derived polytropic index into a

  9. Kelvin-Helmholtz instability of anisotropic magnetized plasma using generalized polytrope laws

    NASA Astrophysics Data System (ADS)

    Prajapati, R. P.; Chhajlani, R. K.; Parihar, A. K.

    2010-02-01

    The problem of Kelvin-Helmholtz (K-H) instability of two superposed compressible magnetized anisotropic pressure plasmas is investigated using generalized polytrope laws. The relevant magnetohydrodynamic (MHD) equations of the problem have been modified using generalized polytrope laws in terms of polytropic indices. The general dispersion relation is obtained using normal mode analysis by applying the appropriate boundary conditions. The conditions for K-H stability, instability and overstability are obtained for MHD and Chew-Goldberger and Low (CGL) set of equations. It is found that the conditions of K-H stability, instability and overstability depend on polytropic indices and magnetic field. We find that in general overstability is not possible unless the new conditions in terms of polytropic indices are not satisfied. The weak magnetic field changes the criteria of K-H instability. The effect of pressure anisotropy is studied on the growth rate of K-H instability. We conclude that increase in pressure anisotropy causes increase in the region of K-H instability.

  10. Effect of Mass Variation on the Radial Oscillations of Differentially Rotating and Tidally Distorted Polytropic Stars

    NASA Astrophysics Data System (ADS)

    Saini, Seema; Kumar, Sunil; Lal, A. K.

    2015-06-01

    A method is proposed to compute the eigenfrequencies of small adiabatic pseudo-radial modes of oscillations of differentially rotating and tidally distorted stellar models by taking into account the effect of mass variations on its equipotential surface inside the stars. The developed approach has been used to compute certain radial modes of oscillations of polytropic models with polytropic indices 1.5, 3.0 and 4.0. The results obtained have been compared with results obtained earlier without taking into account the mass variation. Certain conclusions based on this study have been drawn.

  11. Mass and Charge in Brane-World and Non-Compact Kaluza-Klein Theories in 5 Dim

    NASA Astrophysics Data System (ADS)

    Ponce de Leon, J.

    2003-08-01

    In classical Kaluza-Klein theory, with compactified extra dimensions and without scalar field, the rest mass as well as the electric charge of test particles are constants of motion. We show that in the case of a large extra dimension this is no longer so. We propose the Hamilton-Jacobi formalism, instead of the geodesic equation, for the study of test particles moving in a five-dimensional background metric. This formalism has a number of advantages: (i) it provides a clear and invariant definition of rest mass, without the ambiguities associated with the choice of the parameters used along the motion in 5D and 4D, (ii) the electromagnetic field can be easily incorporated in the discussion, and (iii) we avoid the difficulties associated with the ``splitting'' of the geodesic equation. For particles moving in a general 5D metric, we show how the effective rest mass, as measured by an observer in 4D, varies as a consequence of the large extra dimension. Also, the fifth component of the momentum changes along the motion. This component can be identified with the electric charge of test particles. With this interpretation, both the rest mass and the charge vary along the trajectory. The constant of motion is now a combination of these quantities. We study the cosmological variations of charge and rest mass in a five-dimensional bulk metric which is used to embed the standard k = 0 FRW universes. The time variations in the fine structure ``constant'' and the Thomson cross section are also discussed.

  12. Design of a compact, low-energy-charged-particle-spectrometer for stellar nucleosynthesis experiments at OMEGA and the NIF

    NASA Astrophysics Data System (ADS)

    Armstrong, E.; Frenje, J.; Gatu Johnson, M.; Li, C. K.; Rinderknecht, H.; Rosenberg, M.; Seguin, F. H.; Sio, H.; Zylstra, A.; Petrasso, R. D.

    2014-10-01

    A compact ``Orange'' Spectrometer is being designed for measurements of alpha and proton spectra in the range of ~ 1-5 MeV, produced in low-yield 3He3He experiments at the OMEGA laser and at the National Ignition Facility (NIF). Particle ray-tracing through magnetic fields, modeled by COMSOL, were conducted with the code Python. The goal is to identify an optimal setup for a spectrometer to measure alpha particles at relatively low energies and at low yield. Ability to study the alpha particles in addition to the protons is essential for understanding the nuclear physics governing the final-state interactions between pairs of particles in the three-body final state. This work was supported in part by the U.S. DOE and NLUF.

  13. Structure-distortion of polytropic stars by differential rotation: Third-order perturbation theory

    Microsoft Academic Search

    V. S. Geroyannis; G. A. Antonakopoulos

    1981-01-01

    In order to specify the structure of a rapidly and differentially rotating gaseous polytrope, we extend Chandrasekhar's perturbation theory to include third-order terms in the perturbation parameter. In the present paper, the theory developed is required for a subsequent numerical treatment of the structure-determination.

  14. set of polytropes to resemble the stellar evolution structure. Convection is

    E-print Network

    Herwig, Falk

    set of polytropes to resemble the stellar evolution structure. Convection is driven by a constant-D run. The computational domain includes 11.4 pressure scale heights. He-shell flash convection is dominated by large convective cells that are centered in the lower half of the convection zone (Fig. 1

  15. Compact, high power capacitor charger

    Microsoft Academic Search

    M. GiesselmannS; T. Heeren; T. Helle

    2003-01-01

    We are developing compact, high-power chargers for rapid charging of energy storage capacitors. The main application is presently rapid charging of the capacitors inside of compact Marx generators for reprated operation. Compact Marx generators produce output pulses with amplitudes above 300 kV with ns or subns rise-times. A typical application is the generation of high power microwaves. Initially all energy

  16. Effective geometry of the n=1 uniformly rotating self-gravitating polytrope

    SciTech Connect

    Bini, D.; Cherubini, C.; Filippi, S.; Geralico, A. [Istituto per le Applicazioni del Calcolo 'M. Picone', CNR, I-00185 Rome (Italy) and ICRA, University of Rome 'La Sapienza', I-00185 Rome (Italy); Nonlinear Physics and Mathematical Modeling Lab, Engineering Faculty, University Campus Bio-Medico, I-00128 Rome (Italy) and ICRA, University of Rome 'La Sapienza', I-00185 Rome (Italy); Physics Department and ICRA, University of Rome 'La Sapienza', I-00185 Rome (Italy)

    2010-08-15

    The ''effective geometry'' formalism is used to study the perturbations of a perfect barotropic Newtonian self-gravitating rotating and compressible fluid coupled with gravitational backreaction. The case of a uniformly rotating polytrope with index n=1 is investigated, due to its analytical tractability. Special attention is devoted to the geometrical properties of the underlying background acoustic metric, focusing, in particular, on null geodesics as well as on the analog light cone structure.

  17. The effective geometry of the $n=1$ uniformly rotating self-gravitating polytrope

    E-print Network

    Donato Bini; Christian Cherubini; Simonetta Filippi; Andrea Geralico

    2014-08-20

    The \\lq\\lq effective geometry" formalism is used to study the perturbations of a perfect barotropic Newtonian self-gravitating rotating and compressible fluid coupled with gravitational backreaction. The case of a uniformly rotating polytrope with index $n=1$ is investigated, due to its analytical tractability. Special attention is devoted to the geometrical properties of the underlying background acoustic metric, focusing in particular on null geodesics as well as on the analog light cone structure.

  18. Compact baby Skyrmions

    SciTech Connect

    Adam, C. [Departamento de Fisica de Particulas, Universidad de Santiago and Instituto Galego de Fisica de Altas Enerxias (IGFAE), E-15782 Santiago de Compostela (Spain); Klimas, P. [Instituto de Fisica de Sao Carlos, Universidade de Sao Carlos, Caixa Postal 369, CEP 13560-970, Sao Carlos-SP (Brazil); Sanchez-Guillen, J. [Departamento de Fisica de Particulas, Universidad de Santiago and Instituto Galego de Fisica de Altas Enerxias (IGFAE), E-15782 Santiago de Compostela (Spain); Wereszczynski, A. [Institute of Physics, Jagiellonian University, Reymonta 4, Krakow (Poland)

    2009-11-15

    For the baby Skyrme model with a specific potential, compacton solutions, i.e., configurations with a compact support and parabolic approach to the vacuum, are derived. Specifically, in the nontopological sector, we find spinning Q-balls and Q-shells, as well as peakons. Moreover, we obtain compact baby skyrmions with nontrivial topological charge. All these solutions may form stable multisoliton configurations provided they are sufficiently separated.

  19. An empirical determination of the polytropic index for the free-streaming solar wind using Helios 1 data

    NASA Technical Reports Server (NTRS)

    Totten, T. L.; Freeman, J. W.; Arya, S.

    1995-01-01

    Observations of solar wind proton temperatures indicate that the solar wind is heated as it moves outward toward the orbit of Earth. This heating, which may be the results of electron heat conduction and perhaps MHD waves, has proven difficult to quantify and hence is often neglected in MHD models of the solar wind. An alternate approach to finding explicit heating terms for the MHD energy equation is to use a polytropic approximation. This paper discusses the properties of the polytropic approximation and its application to the solar wind plasma. By using data from the Helios 1 spacecraft, an empirical value for the polytropic index of the free-streaming solar wind is determined. Various corrections to the data are made to account for velocity, nonuniformity in radial sampling, and stream interaction regions. The polytropic index, as derived from proton data, is found to indepedent of speed state, within statistical error, and has an average value of 1.46. If magnetic pressure is included, the polytropic index has an average value of 1.58.

  20. VISCOUS ACCRETION OF A POLYTROPIC SELF-GRAVITATING DISK IN THE PRESENCE OF WIND

    SciTech Connect

    Abbassi, Shahram; Nourbakhsh, Erfan [School of Physics, Damghan University, P.O. Box 36715-364, Damghan (Iran, Islamic Republic of); Shadmehri, Mohsen, E-mail: abbassi@ipm.ir, E-mail: e.nourbakhsh@mail.sbu.ac.ir, E-mail: m.shadmehri@gu.ac.ir [Department of Physics, Golestan University, Basij Square, Gorgan (Iran, Islamic Republic of)

    2013-03-10

    Self-similar and semi-analytical solutions are found for the height-averaged equations governing the dynamical behavior of a polytropic, self-gravitating disk under the effects of winds around the nascent object. In order to describe the time evolution of the system, we adopt a radius-dependent mass loss rate, then highlight its importance on both the traditional {alpha} and innovative {beta} models of viscosity prescription. In agreement with some other studies, our solutions represent that the Toomre parameter is less than one in most regions on the {beta}-disk, which indicates that in such disks gravitational instabilities can occur at various distances from the central accretor. So, the {beta}-disk model might provide a good explanation of how the planetary systems form. The purpose of the present work is twofold: examining the structure of a disk with wind in comparison to a no-wind solution and seeing whether the adopted viscosity prescription significantly affects the dynamical behavior of the disk-wind system. We also considered the temperature distribution in our disk by a polytropic condition. The solutions imply that, under our boundary conditions, the radial velocity is larger for {alpha}-disks and increases as wind becomes stronger in both viscosity models. Also, we noticed that the disk thickness increases by amplifying the wind or adopting larger values for the polytropic exponent {gamma}. It also may globally decrease if one prescribes a {beta}-model for the viscosity. Moreover, in both viscosity models, the surface density and mass accretion rate diminish as the wind gets stronger or {gamma} increases.

  1. Radial pulsations of neutron stars: computing alternative polytropic models regarding density and adiabatic index

    E-print Network

    Vassilis Geroyannis; Georgios Kleftogiannis

    2014-06-14

    We revisit the problem of radial pulsations of neutron stars by computing four general-relativistic polytropic models, in which "density" and "adiabatic index" are involved with their discrete meanings: (i) "rest-mass density" or (ii) "mass-energy density" regarding the density, and (i) "constant" or (ii) "variable" regarding the adiabatic index. Considering the resulting four discrete combinations, we construct corresponding models and compute for each model the frequencies of the lowest three radial modes. Comparisons with previous results are made. The deviations of respective frequencies of the resolved models seem to exhibit a systematic behavior, an issue discussed here in detail.

  2. Closure of the hierarchy of fluid equations by means of the polytropic-coefficient function (PCF)

    SciTech Connect

    Kuhn, S.; Kamran, M.; Jelic, N. [Association EURATOM-OAeW, Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Kos, L. [LECAD Laboratory, University of Ljubljana, SI-1000 Ljubljana (Slovenia); Tskhakaya, D. jr; Tskhakaya, D. D. sr [Association EURATOM-OAeW, Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Andronikashvili Institute of Physics, Georgian Academy of Sciences, Tbilisi 0177 (Georgia)

    2010-12-14

    The continuity and momentum equations of a fluid plasma component may be viewed as four scalar evolution equations for the four scalar fluid variables n(x-vector,t)(density) and u(x-vector,t)(fluid velocity), which are zeroth- and first order velocity moments of the velocity distribution function (VDF). However, the momentum equation in addition contains the gradient of the pressure p(x-vector,t), which is a second-order velocity moment for which another equation, the 'closure equation', is needed. In the present work, closure by means of the polytropic-coefficient function (PCF) is discussed which, by analogy with the well-known polytropic coefficient (also called the 'polytropic index' or 'polytropic exponent') in macroscopic thermodynamic systems, is formally defined by {gamma}(x-vector,t) = (nDp/Dt)(pDn/Dt) = (n/p)(Dp/Dn), with D/Dt = {partial_derivative}/{partial_derivative}t+u-vector{center_dot}{partial_derivative}/{partial_derivative}x-vector, which amounts to the closure equation if {gamma}(x-vector,t) is known. In fluid problems, however, the PCF is usually unknown and hence must be assumed or guessed, but in kinetic problems it can be calculated exactly. These general concepts are first developed and then applied specifically to the basic Tonks-Langmuir (TL) model [L. Tonks and I. Langmuir, Phys. Rev. 34, 876, 1929]. It is shown for the first time that results obtained from the fluid equations closed with the correct PCF coincide with the corresponding results calculated on the basis of the exact kinetic solution [K.-U. Riemann, Phys. Plasmas 13, 063508 (2006)], but differ visibly from those obtained from the approximate fluid equations closed with the zero-pressure approximation [Riemann et al., Plasma Phys. Control. Fusion 47, 1949 (2005)]. Also, it is again confirmed that the correct PCF may be a strongly varying function of position, so that the simple constant values of {gamma} usually assumed [K.-U. Riemann, XXVIII International Conference on Phenomena in Ionized Gases, 479 (2007)] may lead to markedly erroneous results especially near material walls. All of these findings lead us to conclude that better approximations to the PCF are needed for closing fluid equations in an appropriate manner.

  3. Vortex laws and field line invariants in polytropic field-aligned MHD flow

    NASA Astrophysics Data System (ADS)

    Sonnerup, B. U. O.; Hau, L.-N.

    1994-01-01

    The consequences of conservation of angular momentum in, single- or double-polytropic, steady, compressible, magnetohydrodynamic (MHD) flow parallel to the magnetic field are examined, the principal result being the MHD counterparts of Crocco's theorem and Lord Kelvin's theorem, both expressed in terms of a generalized vorticity. Under special assumptions concerning geometry and/or homogeneity of the general field line invariants, these vortex laws lead to additional field line invariants which describe the conservation of generalized angular momentum in the plasma, taking into account torques produced by j x B forces and Coriolis forces.

  4. GRMHD Simulations of Binary Neutron Star Mergers with Piecewise Polytropic Equations of State

    NASA Astrophysics Data System (ADS)

    Giacomazzo, Bruno

    2015-04-01

    We present new results of fully general relativistic magnetohydrodynamic (GRMHD) simulations of binary neutron star (BNS) mergers performed with the Whisky code. Our new simulations consider both equal and unequal-mass systems and describe the NS matter via piecewise polytropic equations of state (EOSs). BNS mergers are powerful sources of gravitational waves (GWs) that can be detected by ground based detectors, such as advanced Virgo and LIGO, and they are also thought to be behind the central engine powering short gamma-ray bursts. In our simulations we therefore focus both on the GW emission and on the dynamics of matter and magnetic fields, both in the case a black hole is promptly formed and in the case of the formation of a long-lived magnetized NS. Since the EOS has an important role in both GW emission and matter dynamics, our simulations employ piecewise polytropic EOSs composed by seven pieces, four for the low-density regions (including the crust) and three for the core, in order to more accurately match physically motivated EOSs. Thermal effects are also included in order to more properly describe the post-merger dynamics.

  5. An exact solution for arbitrarily rotating gaseous polytropes with index unity

    NASA Astrophysics Data System (ADS)

    Kong, Dali; Zhang, Keke; Schubert, Gerald

    2015-03-01

    Many gaseous planets and stars are rapidly rotating and can be approximately described by a polytropic equation of state with index unity. We present the first exact analytic solution, under the assumption of the oblate spheroidal shape, for an arbitrarily rotating gaseous polytrope with index unity in hydrostatic equilibrium, giving rise to its internal structure and gravitational field. The new exact solution is derived by constructing the non-spherical Green's function in terms of the oblate spheroidal wavefunction. We then apply the exact solution to a generic object whose parameter values are guided by the observations of the rapidly rotating star ? Eridani with its eccentricity E_{? }= 0.7454, the most oblate star known. The internal structure and gravitational field of the object are computed from its assumed rotation rate and size. We also compare the exact solution to the three-dimensional numerical solution based on a finite-element method taking full account of rotation-induced shape change and find excellent agreement between the exact solution and the finite-element solution with about 0.001 per cent discrepancy.

  6. Acoustic oscillations of rapidly rotating polytropic stars. II. Effects of the Coriolis and centrifugal accelerations

    E-print Network

    D. Reese; F. Lignières; M. Rieutord

    2006-09-26

    Context: With the launch of space missions devoted to asteroseismology (like COROT), the scientific community will soon have accurate measurements of pulsation frequencies in many rapidly rotating stars. Aims: The present work focuses on the effects of rotation on pulsations of rapidly rotating stars when both the Coriolis and centrifugal accelerations require a non-perturbative treatment. Method: We develop a 2-dimensional spectral numerical approach which allows us to compute acoustic modes in centrifugally distorted polytropes including the full influence of the Coriolis force. This method is validated through comparisons with previous studies, and the results are shown to be highly accurate. Results: In the frequency range considered and with COROT's accuracy, we establish a domain of validity for perturbative methods, thus showing the need for complete calculations beyond v.sin i = 50 km/s for a R = 2.3 R_\\odot, M = 1.9 M_\\odot polytropic star. Furthermore, it is shown that the main differences between complete and perturbative calculations come essentially from the centrifugal distortion.

  7. Re-examination of Polytropic Spheres in Palatini f(R) Gravity

    E-print Network

    Gonzalo J. Olmo

    2008-10-20

    We investigate spherically symmetric, static matter configurations with polytropic equation of state for a class of f(R) models in Palatini formalism and show that the surface singularities recently reported in the literature are not physical in the case of Planck scale modified lagrangians. In such cases, they are just an artifact of the idealized equation of state used. In fact, we show that for the models f(R)=R\\pm\\lambda R^2, with \\lambda on the order of the Planck length squared, the presence of a single electron in the Universe would be enough to cure all stellar singularities of this type. From our analysis it also follows that the stellar structure derived from these lagrangians is virtually undistinguishable from that corresponding to General Relativity. For ultraviolet corrected models far from the Planck scale, however, the surface singularities may indeed arise in the region of validity of the polytropic equation of state. This fact can be used to place constraints on the parameters of particular models.

  8. Compact monolithic capacitive discharge unit

    DOEpatents

    Roesler, Alexander W. (Tijeras, NM); Vernon, George E. (Rio Rancho, NM); Hoke, Darren A. (Albuquerque, NM); De Marquis, Virginia K. (Tijeras, NM); Harris, Steven M. (Albuquerque, NM)

    2007-06-26

    A compact monolithic capacitive discharge unit (CDU) is disclosed in which a thyristor switch and a flyback charging circuit are both sandwiched about a ceramic energy storage capacitor. The result is a compact rugged assembly which provides a low-inductance current discharge path. The flyback charging circuit preferably includes a low-temperature co-fired ceramic transformer. The CDU can further include one or more ceramic substrates for enclosing the thyristor switch and for holding various passive components used in the flyback charging circuit. A load such as a detonator can also be attached directly to the CDU.

  9. Linear and nonlinear Kelvin-Helmholtz instabilities of high velocity magnetized shear layers with generalized polytrope laws

    Microsoft Academic Search

    Kevin George Brown

    1999-01-01

    The linear and nonlinear Kelvin-Helmholtz instability of tangential velocity discontinuities in high velocity magnetized plasmas with isotropic or anisotropic pressure is investigated. This problem is important in various geophysical, astrophysical and space configurations where there are spatially varying flow speeds. A new analytical technique applied to the magnetohydrodynamic equations with generalized polytrope laws (for the pressure parallel and perpendicular to

  10. Compact Reactor

    SciTech Connect

    Williams, Pharis E. [Williams Research, P.O. Box 554, Los Alamos, NM87544 (United States)

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  11. Self-gravitating rotating anisotropic pressure plasma in presence of Hall current and electrical resistivity using generalized polytrope laws

    SciTech Connect

    Prajapati, R. P.; Chhajlani, R. K. [School of Studies in Physics, Vikram University, Ujjain-456010 (M.P.) (India); Soni, G. D. [Government Girls Degree College, Dewas, (M.P.) (India)

    2008-06-15

    The effects of uniform rotation, finite electrical resistivity, electron inertia, and Hall current on the self-gravitational instability of anisotropic pressure plasma with generalized polytrope laws have been studied. A general dispersion relation is obtained with the help of the relevant linearized perturbed magnetohydrodynamic (MHD) equations incorporating the relevant contributions of various effects of the problem using the method of normal mode analysis. The general dispersion relation is further reduced for the special cases of rotation; i.e., parallel and perpendicular to the direction of the magnetic field. The longitudinal and transverse modes of propagation are discussed separately for investigation of condition of instability. The effects of rotation, Hall current, finite electron inertia, and polytropic indices are discussed on the gravitational, ''firehose,'' and ''mirror'' instabilities. The numerical calculations have been performed to obtain the dependence of the growth rate of the gravitational unstable mode on the various physical parameters involved. The finite electrical resistivity, rotation, and Hall current have a stabilizing influence on the growth rate of the unstable mode of wave propagation. The finite electrical resistivity removes the effect of magnetic field and polytropic index from the condition of instability in the transverse mode of propagation for both the cases of rotation. It is also found that the Jeans criterion of gravitational instability depends upon rotation, electron inertia, and polytropic indices. In the case of transverse mode of propagation with the axis of rotation parallel to the magnetic field, it is observed that the region of instability and the value of the critical Jeans wavenumber are larger for the Chew-Goldberger-Low set of equations in comparison with the MHD set of equations. The stability of the system is discussed by applying Routh-Hurwitz criterion. The inclusion of rotation or Hall current or both together depresses the growth rate of mirror instability. We also note that the condition of mirror instability depends upon polytropic indices.

  12. Hydrodynamics of binary coalescence. 2: Polytropes with gamma = 5/3

    NASA Technical Reports Server (NTRS)

    Rasio, Frederic A.; Shapiro, Stuart L.

    1995-01-01

    We present a new numerical study of the equilibrium and stability properties of close binary systems. We use the smoothed-particle hydrodynamics (SPH) technique both to construct accurate equilibrium configurations in three dimensions and to follow their hydrodynamic evolution. We adopt a simple polytropic equation of state p = K(sub rho)(exp gamma) with gamma = 5/3 and K = constant within each star, applicable to low-mass degenerate dwarfs as well as low-mass main-sequence stars. For degenerate configurations, we set the two polytropic constants equal, K = K prime, independent of the mass ratio. For main-sequence stars, we adjust K and K prime so as to obtain a simple mass-radius relation of the form R/R prime = M/M prime, where R prime and M prime are the radius and mass of the secondary. Along a sequence of binary equilibrium configurations for two identical stars, we demonstrate the existence of both secular and dynamical instabilities, confirming directly the results of recent analytic work. We use the SPH method to calculate the nonlinear development of the dynamical instability and to determine the final fate of the system. We find that the two stars merge together into a single, rapidly rotating object in just a few orbital periods. Equilibrium sequences are also constructed for systems containing two nonidentical stars. These sequences terminate at a Roche limit, which we can determine very accurately using SPH. For two low-mass main-sequence stars with mass ratio q approximately less than 0.4 we find that the (synchronized) Roche limit configuration is secularly unstable. We discuss the implications of our results for the evolution of double white-dwarf systems and W Ursae Majoris binaries.

  13. Analytical families of two-component anisotropic polytropes and their relativistic extensions

    NASA Astrophysics Data System (ADS)

    Nguyen, Phuc H.; Lingam, Manasvi

    2013-12-01

    In this paper, we study a family of two-component anisotropic polytropes which model a wide range of spherically symmetric astrophysical systems such as early-type baryonic galaxies. This family is found to contain a large class of models such as the hypervirial family (which satisfy the virial theorem locally), the Plummer and Hernquist models and Navarro-Frenk-White (NFW) like models. The potential-density pair for these models are derived, as well as their velocity dispersions and anisotropy parameters. The projected quantities are computed and found to reduce to analytical expressions in some cases. The first section of this paper presents an extension of the two-term anisotropic polytropes to encompass a very wide range of potential-density pairs. In the next section, we present the general relativistic extension of the potential-density pair and calculate the stress-energy tensor, the relativistic anisotropy parameter, the velocity of circular orbits and the angular momentum. Remarkably, for the case of the hypervirial family, the relativistic pressure in the Newtonian limit and the relativistic anisotropy parameter are found to coincide with the corresponding Newtonian expressions. The weak, dominant and strong energy conditions are found to be satisfied only for a certain range of the free parameters. We show that the relativistic hypervirial family also has a finite total mass like its Newtonian counterpart. In the first appendix, a relativistic extension of a different hypervirial family of models is studied and the relativistic anisotropy parameter is found to coincide with the Newtonian one. Finally, we present a family of models obtained from our distribution function that are similar to the Ossipkov-Merritt models; by computing their anisotropy parameters, we show that they model systems with isotropic cores and radially anisotropic exteriors.

  14. PHYSICAL REVIEW SPECIAL TOPICS -ACCELERATORS AND BEAMS, VOLUME 5, 072801 (2002) Compact high-resolution retarding field energy analyzer for space-charge-dominated

    E-print Network

    Valfells, Ágúst

    2002-01-01

    spread of space-charge-dominated electron beams. This energy analyzer has a cylindrical electrode Advanced particle accelerators for heavy-ion inertial fu- sion, high-energy colliders, free electron lasers Ring (UMER) [2] currently being constructed, re- quire knowledge of the beam's energy spread

  15. Compact Storage

    USGS Multimedia Gallery

    After a detailed inventory is completed and published on the web, processed materials are stored in compact shelving in the Field Records Collection. Collections are organized by scientist and project....

  16. Compaction managed mirror bend achromat

    DOEpatents

    Douglas, David (Yorktown, VA)

    2005-10-18

    A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

  17. An empirical polytrope law for solar wind thermal electrons between 0.45 and 4.76 AU: Voyager 2 and Mariner 10

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.; Scudder, J. D.

    1979-01-01

    Empirical evidence is presented that solar wind thermal electrons obey a polytrope law with polytrope index gamma = 1.175 plus or minus 0.03. The Voyager 2 and Mariner 10 data used as evidence are compared and discussed. The theoretical predictions that solar wind thermal electrons in the asymptotic solar wind should obey a polytrope law with polytrope index gamma = 1.16 plus or minus. The widespread impressions in the literature that solar wind electrons behave more like an isothermal than adiabatic gas, and the arguments that Coulomb collisions are the dominant stochastic process shaping observed electron distribution functions in the solar wind are reexamined, reviewed and evaluated. The assignment of the interplanetary potential as equal to approximately seven times the temperature of the thermal electrons is discussed.

  18. Hydrodynamics of binary coalescence. 1: Polytropes with stiff equations of state

    NASA Technical Reports Server (NTRS)

    Rasio, Frederic A.; Shapiro, Stuart L.

    1994-01-01

    We performed a series of three-dimensional hydrodynamic calculations of binary coalescence using the smoothed particle hydrodynamics (SPH) method. The initial conditions are exact polytropic equilibrium configurations on the verge of dynamical instability. We consider synchronized equilbria only and concentrate on stiff equations of state, with adiabatic Gamma greater than 5/3. We assume that the polytropic constants (K identically equal to P/(rho(exp Gamma)) are the same for both components. These conditions apply well to models of neutron star binaries. Accordingly, we discuss our results in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO) project, and we calculate the emission of gravitational radiation in the quadruple approximation. The fully nonlinear development of the instability is followed using SPH until a new equilibrium configuration is reached by the system. We find that the properties of this final configuration depend sensitively on both the compressibility and mass ratio. An axisymmetric merged configuration is always produced when the adiabatic exponent Gamma approximately less than 2.3. As a consequence, the emission of gravitational radiation shuts off abruptly right after the onset of dynamical instability. In contrast, triaxial merged configurations are obtained when Gamma approximately greater than 2.3, and the system continues to emit gravitational waves after the final coalescence. Systems with mass ratios q not equal to 1 typically become dynamically unstable before the onset of mass transfer. Stable mass transfer from one neutron star to another in a close binary is therefore probably ruled out. For a mass ratio q approximately less than 0.5, however, dynamical mass transfer can temporarily retard the coalescence by causing a rapid reexpansion of the binary into a new, slightly eccentric but dynamically stable orbit. The maximum amplitude h(sub max) and peak luminosity L(sub max) of the gravitational waves emitted during the final coalescence are nearly independent of Gamma, but depend sensitively on the mass ratio q. The approximate scalings we find are h(sub max) varies as q(exp 2) and L(sub max) varies as q(exp 6) for q close to unity.

  19. Effect of pressure anisotropy and flow velocity on Kelvin-Helmholtz instability of anisotropic magnetized plasma using generalized polytrope laws

    SciTech Connect

    Prajapati, R. P.; Chhajlani, R. K. [School of Studies in Physics, Vikram University, Ujjain, Madhya Pradesh 456010 (India)

    2010-11-15

    The effect of pressure anisotropy and flow velocity on the Kelvin-Helmholtz (KH) instability of two magnetized anisotropic pressure plasmas flowing relative to each other is investigated using generalized polytrope laws. The anisotropic pressure with the generalized polytrope laws is considered with three-dimensional perturbations in the description of plasma using relevant magnetohydrodynamic (MHD) set of equations. The magnetic field is assumed in the x-direction and parallel to the direction of the flow of plasma streams. A complete polytrope model is given for the considered system in terms of pressure components, magnetic field, and density of the fluids to discuss the condition of KH instability, stability, and overstability. The problem is solved using the normal mode analysis and the general dispersion relation is obtained by applying the appropriate boundary conditions. The case of nonvanishing wavenumber transverse to the direction of the stream is obtained, which represents the stationery configuration without excitation of KH instability. The longitudinal mode of propagation is discussed with conditions of KH instability, stability, and overstability for collisionless (anisotropic) double-adiabatic Chew-Goldberger-Low (CGL) and collisional (isotropic) MHD media, depending on various values of polytrope indices. The effects of pressure anisotropy, different flow velocities, and magnetic field are also discussed on the growth rate of KH instability. We observe that the presence of flow velocity and pressure anisotropy of the plasmas has a destabilizing influence on the growth rate of the system. The growth rate is found larger for MHD set of equations in comparison to the CGL set of equations. The presence of magnetic field has a stabilizing role on the growth rate of the considered system.

  20. Acoustic oscillations in rapidly rotating polytropic stars I. Effects of the centrifugal distortion

    E-print Network

    F. Lignieres; M. Rieutord; D. Reese

    2006-04-13

    A new non-perturbative method to compute accurate oscillation modes in rapidly rotating stars is presented. In this paper, the effect of the centrifugal force is fully taken into account while the Coriolis force is neglected. This assumption is valid when the time scale of the oscillation is much shorter than the inverse of the rotation rate and is expected to be suitable for high radial order p-modes of $\\delta$ Scuti stars. Axisymmetric p-modes have been computed in uniformly rotating polytropic models of stars. In the frequency and rotation range considered, we found that as rotation increases (i) the asymptotic structure of the non-rotating frequency spectrum is first destroyed then replaced by a new form of organization (ii) the mode amplitude tends to concentrate near the equator (iii) differences with perturbative methods become significant as soon as the rotation rate exceeds about fifteen percent of the Keplerian limit. The implications for the seismology of rapidly rotating stars are then discussed.

  1. GRAVITATIONAL INSTABILITY OF ROTATING, PRESSURE-CONFINED, POLYTROPIC GAS DISKS WITH VERTICAL STRATIFICATION

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Seo, Young Min; Hong, Seung Soo, E-mail: jgkim@astro.snu.ac.kr, E-mail: wkim@astro.snu.ac.kr, E-mail: seo3919@email.arizona.edu, E-mail: sshong@astro.snu.ac.kr [FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2012-12-20

    We investigate the gravitational instability (GI) of rotating, vertically stratified, pressure-confined, polytropic gas disks using a linear stability analysis as well as analytic approximations. The disks are initially in vertical hydrostatic equilibrium and bounded by a constant external pressure. We find that the GI of a pressure-confined disk is in general a mixed mode of the conventional Jeans and distortional instabilities, and is thus an unstable version of acoustic-surface-gravity waves. The Jeans mode dominates in weakly confined disks or disks with rigid boundaries. On the other hand, when the disk has free boundaries and is strongly pressure confined, the mixed GI is dominated by the distortional mode that is surface-gravity waves driven unstable under their own gravity and thus incompressible. We demonstrate that the Jeans mode is gravity-modified acoustic waves rather than inertial waves and that inertial waves are almost unaffected by self-gravity. We derive an analytic expression for the effective sound speed c{sub eff} of acoustic-surface-gravity waves. We also find expressions for the gravity reduction factors relative to a razor-thin counterpart that are appropriate for the Jeans and distortional modes. The usual razor-thin dispersion relation, after correcting for c{sub eff} and the reduction factors, closely matches the numerical results obtained by solving a full set of linearized equations. The effective sound speed generalizes the Toomre stability parameter of the Jeans mode to allow for the mixed GI of vertically stratified, pressure-confined disks.

  2. Glycosylation of the envelope glycoprotein from a polytropic murine retrovirus in two different host cells.

    PubMed

    Geyer, H; Kempf, R; Schott, H H; Geyer, R

    1990-11-13

    A polytropic recombinant retrovirus containing the envelope gene of Friend mink cell focus-inducing virus plus the remainder of the genome of an amphoropic murine leukemia virus was propagated on mouse embryo fibroblasts and mink lung cells. Virus particles, metabolically labeled with [2-3H]mannose, were harvested from the culture supernatants and lysed with detergents. The viral envelope glycoprotein was isolated from the lysates by immunoaffinity chromatography and purified by preparative SDS/PAGE. Oligosaccharides were liberated by sequential treatment of tryptic glycopeptides with endo-beta-N-acetylglucosaminidase H and peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase F and fractionated by high-performance liquid chromatography. Individual glycans were characterized chromatographically, by methylation analyses and in part, by enzymic microsequencing. The results demonstrated that viral glycoproteins, synthesized in mouse embryo fibroblasts, carried as major constituents partially fucosylated diantennary, 2,4- and 2,6-branched triantennary and tetraantennary complex type N-glycans with 0-4 sialic acid residues and only small amounts of high-mannose type species with 5-9 mannose residues. As a characteristic feature, part of the complex type glycans contained additional Gal(alpha 1-3) substituents. Glycoprotein obtained from virions propagated on mink lung cells, contained partially fucosylated diantennary and 2,4-branched triantennary oligosaccharides with 1-3 sialic acid residues, in addition to trace amounts of high-mannose type species with 8 or 9 mannose residues. Thus, the results reveal that predominantly, the complex type N-glycans of the retroviral envelope glycoprotein display cell-specific variations including differences in oligosaccharide branching, sialylation and substitution by additional Gal(alpha 1-3) residues. PMID:2174368

  3. Compact HPD

    SciTech Connect

    Suyama, M.; Kawai, Y.; Kimura, S. [Hamamatsu Photonics K.K., Shizuoka (Japan)] [and others

    1996-12-31

    In order to be utilized in such application fields as high energy physics or medical imaging, where a huge number of photodetectors are assembled in designated small area, the world`s smallest HPD, the compact BFD, has been developed. The overall diameter and the length of the tube are 16mm and 15mm, respectively. The effective photocathode area is 8mm in diameter. At applied voltage of -8kV to the photocathode, the electron multiplication gain of a PD incorporated HPD (PD-BPD) is 1,600, and that of an APD (APD-BPD) is 65,000. In the pulse height distribution measurement, photoelectron peaks up to 6 photoelectrons are clearly distinguishable with the APD-BPD. Experiments established that there was no degradation of gain in magnetic fields up to 1.5T, an important performance characteristic of the compact BPD for application in high energy physics.

  4. cap alpha. -Particle confinement in compact tori

    SciTech Connect

    Bozhokin, S.V.

    1986-11-01

    The motion of high-energy ..cap alpha.. particles in compact tori is studied. The classically accessible regions of motion of charged particles are found. The conditions are formulated under which the ..cap alpha.. particles produced in fusion reactions are absolutely confined. An ..cap alpha.. particle starting in a region enclosed by a ''critical'' surface will never, in the course of its motion, intersect the separatrix of a compact torus. These critical surfaces are constructed. The ratio of the volume of absolute ..cap alpha.. confinement to the total volume of a compact torus is calculated as a function of the magnetic field strength and the dimensions of the compact torus.

  5. A nonclassical Radau collocation method for solving the Lane-Emden equations of the polytropic index 4.75 ? ? < 5

    NASA Astrophysics Data System (ADS)

    Tirani, M. D.; Maleki, M.; Kajani, M. T.

    2014-11-01

    A numerical method for solving the Lane-Emden equations of the polytropic index ? when 4.75 ? ? ? 5 is introduced. The method is based upon nonclassical Gauss-Radau collocation points and Freud type weights. Nonclassical orthogonal polynomials, nonclassical Radau points and weighted interpolation are introduced and are utilized in the interval [0,1]. A smooth, strictly monotonic transformation is used to map the infinite domain x ? [0,?) onto a half-open interval t ? [0,1). The resulting problem on the finite interval is then transcribed to a system of nonlinear algebraic equations using collocation. The method is easy to implement and yields very accurate results.

  6. Compact groups of compact galaxies. IV. [Listing

    Microsoft Academic Search

    Petrosyan

    1974-01-01

    A fourth list of compact groups of compact galaxies is presented. It contains 37 new objects discovered in the Palomar Sky Survey Charts. The regions +90°, +84°, +78°, +0° are completely covered. Photographs of the compact groups of compact galaxies taken from the Palomar charts are appended.

  7. Compact magnetograph

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Gillespie, B. A.; Mosher, J. W.

    1982-01-01

    A compact magnetograph system based on solid Fabry-Perot interferometers as the spectral isolation elements was studied. The theory of operation of several Fabry-Perot systems, the suitability of various magnetic lines, signal levels expected for different modes of operation, and the optimal detector systems were investigated. The requirements that the lack of a polarization modulator placed upon the electronic signal chain was emphasized. The PLZT modulator was chosen as a satisfactory component with both high reliability and elatively low voltage requirements. Thermal control, line centering and velocity offset problems were solved by a Fabry-Perot configuration.

  8. Linear stability analysis of nonaxisymmetric instabilities in self-gravitating polytropic disks

    NASA Astrophysics Data System (ADS)

    Hadley, Kathryn Z.

    An important problem in astrophysics involves understanding the formation of planetary systems. When a star-forming cloud collapses under gravity its rotation causes it to flatten into a disk. Only a small percentage of the matter near the rotation axis falls inward to create the central object, yet our Sun contains over 99% of the matter of our Solar System. We examine how global hydrodynamic instabilities transport angular momentum through the disk causing material to accrete onto the central star. We analyze the stability of polytropic disks in the linear regime. A power law angular velocity of power q is imposed, and the equilibrium disk structure is found through solution of the time-independent hydrodynamic equations via the Hachisu self-consistent field method. The disk is perturbed, and the time-dependent linearized hydrodynamic equations are used to evolve it. If the system is unstable, the characteristic growth rate and frequency of the perturbation are calculated. We consider modes with azimuthal e im[varphi] dependence, where m is an integer and [varphi] is the azimuthal angle. We map trends across a wide parameter space by varying m , q and the ratios of the star-to-disk mass M* /Md and inner-to-outer disk radius r - /r + . We find that low m modes dominate for small r - /r + , increasing to higher r - /r + as M* /Md increases, independent of q . Three main realms of behavior are identified, for M* << Md , M* ? Md and M* >> Md , and analyzed with respect to the I, J and P mode types as discussed in the literature. Analysis shows that for M* << Md , small r - /r + disks are dominated by low m I modes, which give way to high m J modes at high r - /r + . Low m J modes dominate M* ? Md disks for small r - /r + , while higher m I modes dominate for high r - /r + . Behavior diverges with q for M* >> Md systems with high q models approximating M* ? Md characteristics, while low q models exhibit m = 2 I modes dominating where r - /r + < 0.60.

  9. The evolution of highly compact binary stellar systems

    NASA Technical Reports Server (NTRS)

    Rappaport, S.; Joss, P. C.; Webbink, R. F.

    1982-01-01

    A new theoretical treatment of the evolution of highly compact binary systems is presented. The evolution is calculated until almost the entire mass of the secondary has been transferred to the primary or lost from the system. It is assumed that gravitational radiation from the system is the cause of mass transfer. It is found that the structure of the mass-losing star can be approximated by an n = 3/2 polytrope, and as a result a relatively large number of different cases can be explored and some general conclusions drawn. An explanation is found for the existence of a cutoff in the orbital period distribution among the cataclysmic variables and light is shed upon the possible generic relationships among cataclysmic variables, the low-mass X-ray binaries, and the spectrally soft transient X-ray sources.

  10. The generalized second law of thermodynamics for the interacting polytropic dark energy in non-flat FRW universe enclosed by the apparent horizon

    Microsoft Academic Search

    K. Karami; S. Ghaffari

    2010-01-01

    We investigate the validity of the generalized second law of thermodynamics in a non-flat FRW universe containing the interacting polytropic dark energy with cold dark matter. The boundary of the universe is assumed to be enclosed by the dynamical apparent horizon. We show that for this model under thermal equilibrium with the Hawking radiation, the generalized second law is always

  11. A THREE-DIMENSIONAL NUMERICAL SOLUTION FOR THE SHAPE OF A ROTATIONALLY DISTORTED POLYTROPE OF INDEX UNITY

    SciTech Connect

    Kong, Dali; Zhang, Keke [Department of Mathematical Sciences, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom)] [Department of Mathematical Sciences, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Schubert, Gerald [Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567 (United States)] [Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567 (United States); Anderson, John, E-mail: D.Kong@exeter.ac.uk, E-mail: K.Zhang@exeter.ac.uk, E-mail: jdandy@earthlink.net [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)] [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2013-02-15

    We present a new three-dimensional numerical method for calculating the non-spherical shape and internal structure of a model of a rapidly rotating gaseous body with a polytropic index of unity. The calculation is based on a finite-element method and accounts for the full effects of rotation. After validating the numerical approach against the asymptotic solution of Chandrasekhar that is valid only for a slowly rotating gaseous body, we apply it to models of Jupiter and a rapidly rotating, highly flattened star ({alpha} Eridani). In the case of Jupiter, the two-dimensional distributions of density and pressure are determined via a hybrid inverse approach by adjusting an a priori unknown coefficient in the equation of state until the model shape matches the observed shape of Jupiter. After obtaining the two-dimensional distribution of density, we then compute the zonal gravity coefficients and the total mass from the non-spherical model that takes full account of rotation-induced shape change. Our non-spherical model with a polytropic index of unity is able to produce the known mass of Jupiter with about 4% accuracy and the zonal gravitational coefficient J {sub 2} of Jupiter with better than 2% accuracy, a reasonable result considering that there is only one parameter in the model. For {alpha} Eridani, we calculate its rotationally distorted shape and internal structure based on the observationally deduced rotation rate and size of the star by using a similar hybrid inverse approach. Our model of the star closely approximates the observed flattening.

  12. Near- and Far-Field Response to Compact Acoustic Sources in Stratified Convection Zones

    E-print Network

    Cally, Paul S

    2013-01-01

    The role of the acoustic continuum associated with compact sources in the Sun's interior wave field is explored for a simple polytropic model. The continuum produces a near-field acoustic structure -- the so-called `acoustic jacket' -- that cannot be represented by a superposition of discrete normal modes. Particular attention is paid to monochromatic point sources of various frequency and depth, and to the surface velocity power that results, both in the discrete f- and p-mode spectrum and in the continuum. It is shown that a major effect of the continuum is to heal the surface wave field produced by compact sources, and therefore to hide them from view. It is found that the continuous spectrum is not a significant contributor to observable inter-ridge seismic power.

  13. NEAR- AND FAR-FIELD RESPONSE TO COMPACT ACOUSTIC SOURCES IN STRATIFIED CONVECTION ZONES

    SciTech Connect

    Cally, Paul S., E-mail: paul.cally@monash.edu [Monash Centre for Astrophysics and School of Mathematical Sciences, Monash University, Clayton, Victoria 3800 (Australia)

    2013-05-01

    The role of the acoustic continuum associated with compact sources in the Sun's interior wave field is explored for a simple polytropic model. The continuum produces a near-field acoustic structure-the so-called acoustic jacket-that cannot be represented by a superposition of discrete normal modes. Particular attention is paid to monochromatic point sources of various frequency and depth, and to the surface velocity power that results, both in the discrete f- and p-mode spectrum and in the continuum. It is shown that a major effect of the continuum is to heal the surface wave field produced by compact sources, and therefore to hide them from view. It is found that the continuous spectrum is not a significant contributor to observable inter-ridge seismic power.

  14. On effective compactness and sigma-compactness

    E-print Network

    Kanovei, Vladimir

    2011-01-01

    Using the Gandy -- Harrington topology and other methods of effective descriptive set theory, we prove several theorems on compact and sigma-compact pointsets. In particular we show that any $\\Sigma^1_1$ set $A$ of the Baire space $N^N$ either is covered by a countable union of compact $\\Delta^1_1$ sets, or $A$ contains a subset closed in $N^N$ and homeomorphic to $N^N$ (and then $A$ is not covered by a sigma-compact set, of course).

  15. 18 CFR 420.23 - Exempt uses under the Compact.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-WATER SUPPLY CHARGES Water Supply Policy § 420.23 Exempt uses under the Compact. (a) Section 15.1(b) of the Delaware...

  16. 18 CFR 420.23 - Exempt uses under the Compact.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-WATER SUPPLY CHARGES Water Supply Policy § 420.23 Exempt uses under the Compact. (a) Section 15.1(b) of the Delaware...

  17. 18 CFR 420.23 - Exempt uses under the Compact.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-WATER SUPPLY CHARGES Water Supply Policy § 420.23 Exempt uses under the Compact. (a) Section 15.1(b) of the Delaware...

  18. A compact,repetitive trigger generator

    Microsoft Academic Search

    Zheng Chen; Jin-liang Liu; Jing-ming Gao

    2008-01-01

    This paper describes an innovative design of compact trigger generator with repetitive pulse to drive high voltage gas switch. The basic circuit of trigger generator is analyzed by using P-Spice software. The trigger generator consists of a charging capacitor, a pulse transformer, a trigger gas switch and a control circuit. The incorporate design of capacitor and transformer enables the generator

  19. cap alpha. Particle confinement in compact tori

    Microsoft Academic Search

    Bozhokin

    1986-01-01

    The motion of high-energy ..cap alpha.. particles in compact tori is studied. The classically accessible regions of motion of charged particles are found. The conditions are formulated under which the ..cap alpha.. particles produced in fusion reactions are absolutely confined. An ..cap alpha.. particle starting in a region enclosed by a ''critical'' surface will never, in the course of its

  20. Compact plasma accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor)

    2004-01-01

    A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.

  1. Compaction Behavior of Isomalt after Roll Compaction

    PubMed Central

    Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

    2012-01-01

    The suitability of the new isomalt grade galenIQ™ 801 for dry granulation and following tableting is evaluated in this study. Isomalt alone, as well as a blend of equal parts with dibasic calcium phosphate, is roll compacted and tableted. Particle size distribution and flowability of the granules and friability and disintegration time of the tablets are determined. Tensile strength of tablets is related to the specific compaction force during roll compaction and the tableting force. In all cases, the tensile strength increases with raising tableting forces. The specific compaction force has a different influence. For isomalt alone the tensile strength is highest for tablets made from granules prepared at 2 kN/cm and 6 kN/cm and decreases at higher values, i.e., >10 kN/cm. Tensile strength of the blend tablets is almost one third lower compared to the strongest tablets of pure isomalt. Friability of pure isomalt tablets is above the limit. Disintegration time is longest when the tensile strength is at its maximum and decreases with higher porosity and lower tensile strengths. Isomalt proves to be suitable for tableting after roll compaction. Even though the capacity as a binder might not be as high as of other excipients, it is a further alternative for the formulation scientist. PMID:24300366

  2. Apparatus for producing blast furnace coke by coal compaction

    SciTech Connect

    Brayton, W.E.; Fun, F.; Hendrickson, L.G.; Shoenberger, R.W.

    1981-03-24

    The method of producing blast furnace coke by (1) compacting a finely divided coal wherein at least about 60% by weight of the coal has a diameter of less than about 1/8 inch to form a coal compact, which compact immediately after removal from the compacting means comprises at least about 20% by weight of particles having a particle size of less than 1/4 inch in diameter; (2) breaking the thus formed compact such that the bulk density is sufficiently increased to be capable of conversion into coke suitable for use in large blast furnaces upon carbonization thereof; and (3) carbonizing the broken compact to thereby produce blast furnace coke having a minimum hardness of about 68 and a minimum stability of about 55. The compacting is preferably performed at a pressure equivalent to that achieved by passing the finely divided coal between rolls at a pressure applied to the coal of between about 20 and about 60 tons per lineal inch. Also preferably in the breaking step at least about 95% of the compacted coal is reduced to particle sizes rangi from about one inch to less than about 100 mesh. The invention also includes a system comprising a coal blender, a coal compactor, apparatus for breaking the formed coal compact, and a coking oven and apparatus for charging the broken compact into the oven.

  3. Compact homogeneous CR manifolds

    Microsoft Academic Search

    Dmitry V. Alekseevsky; Andrea F. Spiro

    2000-01-01

    We classify all compact simply connected homogeneous CR manifolds $M$ of codimension one and with non-degenerate Levi form up to CR equivalence. The classification is based on our previous results and on a description of the maximal connected compact group $G(M)$ of automorphisms of $M$. We characterize also the standard homogeneous CR manifolds as the homogeneous CR manifolds whose group

  4. Compact Propositional Gödel Logics

    Microsoft Academic Search

    Matthias Baaz; Richard Zach

    1998-01-01

    Entailment in propositional Godel logics can be defined in a natural way. While all infinite sets of truth values yield the same sets of tautologies, the entailment relations diff er. It is shown that there is a rich structure of infinite-valued Godel logics, only one of which is compact. It is also shown that the compact infinite-valued Godel logic is

  5. ACOUSTIC COMPACTION LAYER DETECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The depth and strength of compacted layers in fields have been determined traditionally using the ASAE standardized cone penetrometer method. However, an on-the-go method would be much faster and much less labor intensive. The soil measurement system described here attempts to locate the compacted...

  6. Compaction properties of isomalt

    Microsoft Academic Search

    Gerad K. Bolhuis; Jeffrey J. P. Engelhart; Anko C. Eissens

    2009-01-01

    Although other polyols have been described extensively as filler-binders in direct compaction of tablets, the polyol isomalt is rather unknown as pharmaceutical excipient, in spite of its description in all the main pharmacopoeias. In this paper the compaction properties of different types of ispomalt were studied. The types used were the standard product sieved isomalt, milled isomalt and two types

  7. The .NET Compact Framework

    Microsoft Academic Search

    C. Neable

    2002-01-01

    The .NET Compact Framework lets developers easily and efficiently build robust applications that call XML Web services, thereby letting end users effectively access remote data, cache it locally for use when offline, and interact with it via rich user interfaces. This paper highlights the .NET Compact Framework's design goals, sheds light on what the first version contains, and speculates on

  8. Stabilization of compactible waste

    SciTech Connect

    Franz, E.M.; Heiser, J.H. III; Colombo, P.

    1990-09-01

    This report summarizes the results of series of experiments performed to determine the feasibility of stabilizing compacted or compactible waste with polymers. The need for this work arose from problems encountered at disposal sites attributed to the instability of this waste in disposal. These studies are part of an experimental program conducted at Brookhaven National Laboratory (BNL) investigating methods for the improved solidification/stabilization of DOE low-level wastes. The approach taken in this study was to perform a series of survey type experiments using various polymerization systems to find the most economical and practical method for further in-depth studies. Compactible dry bulk waste was stabilized with two different monomer systems: styrene-trimethylolpropane trimethacrylate (TMPTMA) and polyester-styrene, in laboratory-scale experiments. Stabilization was accomplished by wetting or soaking compactible waste (before or after compaction) with monomers, which were subsequently polymerized. Three stabilization methods are described. One involves the in-situ treatment of compacted waste with monomers in which a vacuum technique is used to introduce the binder into the waste. The second method involves the alternate placement and compaction of waste and binder into a disposal container. In the third method, the waste is treated before compaction by wetting the waste with the binder using a spraying technique. A series of samples stabilized at various binder-to-waste ratios were evaluated through water immersion and compression testing. Full-scale studies were conducted by stabilizing two 55-gallon drums of real compacted waste. The results of this preliminary study indicate that the integrity of compacted waste forms can be readily improved to ensure their long-term durability in disposal environments. 9 refs., 10 figs., 2 tabs.

  9. Saloplastics: processing compact polyelectrolyte complexes.

    PubMed

    Schaaf, Pierre; Schlenoff, Joseph B

    2015-04-17

    Polyelectrolyte complexes (PECs) are prepared by mixing solutions of oppositely charged polyelectrolytes. These diffuse, amorphous precipitates may be compacted into dense materials, CoPECs, by ultracentrifugation (ucPECs) or extrusion (exPECs). The presence of salt water is essential in plasticizing PECs to allow them to be reformed and fused. When hydrated, CoPECs are versatile, rugged, biocompatible, elastic materials with applications including bioinspired materials, supports for enzymes and (nano)composites. In this review, various methods for making CoPECs are described, as well as fundamental responses of CoPEC mechanical properties to salt concentration. Possible applications as synthetic cartilage, enzymatically active biocomposites, self-healing materials, and magnetic nanocomposites are presented. PMID:25771881

  10. Compact Disc Interactive.

    ERIC Educational Resources Information Center

    Valk, Anton

    1987-01-01

    This overview of a digital optical storage medium with a multimedia capability includes a global description of specifications, current status, and elements required to make a CD-I (compact disk interactive) launch possible. (Author/CLB)

  11. Compact homogeneous CR manifolds

    Microsoft Academic Search

    Dmitry V. Alekseevsky; Andrea F. Spiro

    2002-01-01

    We classify all compact simply connected homogeneous CR manifolds M of codimension one and with non-degenerate Levi form up\\u000a to CR equivalence. The classification is based on our previous results and on a description of the maximal connected compact\\u000a group G(M) of automorphisms of M. We characterize also the standard homogeneous CR manifolds as the homogeneous CR manifolds\\u000a whose group

  12. Semi Compactness in Multiset Topology

    E-print Network

    J. Mahanta; D. Das

    2014-11-21

    In this paper, we introduce and study the concepts of semi open SOM) and semi closed (SCM) M-sets in multiset topological spaces.With this generalization of the notions of open and closed sets in M-topology, we generalize the concept of compactness in M-topology as semi compactness. Further semi compactness is generalized as semi whole compactness, semi partial whole compactness and semi full compactness. Some characterizations of these compact spaces are studied in the setting of multiset theory. In each step, several remarks with proper justifications are provided taking the well existing theories of general topology as the base of our study.

  13. Laboratory compaction of cohesionless sands 

    E-print Network

    Delphia, John Girard

    1998-01-01

    laboratory compaction methods have focused on determining the maximum This thesis follows the style and format of the Canadian Geotechnical JournaL possible dry unit weight of the soil (i. e. vibrating table compaction test, modified vibrating table... on the effectiveness of laboratory compaction. 2) Determine the effect of three different laboratory compaction procedures (i. e. Standard Proctor, Modified Proctor and the Vibrating Hammer tests) on the compaction of cohesionless sands. 3 ) Correlate the various...

  14. Physically detached 'compact groups'

    NASA Technical Reports Server (NTRS)

    Hernquist, Lars; Katz, Neal; Weinberg, David H.

    1995-01-01

    A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.

  15. Compact 1000 pps high-voltage nanosecond pulse generator

    Microsoft Academic Search

    Vladimir P. Gubanov; Sergei D. Korovin; Igor V. Pegel; Albert M. Roitman; Vladislav V. Rostov; Aleksei S. Stepchenko

    1997-01-01

    A compact high-voltage nanosecond generator is described with pulse repetition rate of up to 1000 pps. The generator includes a 30-? coaxial forming line charged by a built-in Tesla transformer with high coupling coefficient, and a high voltage (N2) gas gap switch with gas circulating between the electrodes. The maximum forming line charge voltage is 450 kV, the pulse duration

  16. Take Charge!

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students come to understand static electricity by learning about the nature of electric charge, and different methods for charging objects. In a hands-on activity, students induce an electrical charge on various objects, and experiment with electrical repulsion and attraction.

  17. Quantization condition for 't Hooft monopoles in compact simple Lie groups

    Microsoft Academic Search

    F. Englert; P. Windey

    1976-01-01

    The quantization conditions for 't Hooft monopoles and their related conserved topological charges are obtained for all compact simple Lie groups. In addition, all possible Dirac monopoles are classified.

  18. Compact Stellarator Development Plan

    E-print Network

    Development Through Proof of Principle (PoP) and Performance Extension (PE) to DEMO ­ Key Milestones and foreign PE stellarators. · Focus U.S. compact stellarator experiments on 3D physics issues. Can lead Helical Device (PE w/ S/C magnets - Japan) > 3%. Te 10 kev, Ti 5 keV. enhanced confinement. 2-minute

  19. Compact, Integrated Photoelectron Linacs

    Microsoft Academic Search

    David Yu

    2000-01-01

    The innovative compact high energy iniector which has been developed by DULY Research Inc., will have wide scientific industrial and medical applications. The new photoelectron injector integrates the photocathode directly into a multicell linear accelerator with no drift space between the injector and the linac. By focusing the beam with solenoid or permanent magnets, and producing high current with low

  20. COMPACT SCHOOL AND $$ SAVINGS.

    ERIC Educational Resources Information Center

    BAIR, W.G.

    A REVIEW OF THE CRITERIA FOR CONSIDERING THE USE OF A TOTAL ENERGY SYSTEM WITHIN A SCHOOL BUILDING STATES THE WINDOWLESS, COMPACT SCHOOL OFFERS MORE EFFICIENT SPACE UTILIZATION WITH LESS AREA REQUIRED FOR GIVEN STUDENT POPULATION AND LOWER OPERATION COSTS. THE AUTHOR RECOMMENDS THAT THESE BUILDINGS BE WINDOWLESS TO REDUCE HEAT COSTS, HOWEVER, AT…

  1. Compact fusion reactors

    SciTech Connect

    Krakowski, R.A.; Hagenson, R.L.

    1983-01-01

    Compact, high-power-density approaches to fusion power are proposed to improve economic viability through the use of less-advanced technology in systems of considerably reduced scale. The rationale for and the means by which these systems can be achieved are discussed, as are unique technological problems.

  2. Progress in Compact Toroid Experiments

    SciTech Connect

    Dolan, Thomas James

    2002-09-01

    The term "compact toroids" as used here means spherical tokamaks, spheromaks, and field reversed configurations, but not reversed field pinches. There are about 17 compact toroid experiments under construction or operating, with approximate parameters listed in Table 1.

  3. Internal Charging

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.

    2014-01-01

    (1) High energy (>100keV) electrons penetrate spacecraft walls and accumulate in dielectrics or isolated conductors; (2) Threat environment is energetic electrons with sufficient flux to charge circuit boards, cable insulation, and ungrounded metal faster than charge can dissipate; (3) Accumulating charge density generates electric fields in excess of material breakdown strenght resulting in electrostatic discharge; and (4) System impact is material damage, discharge currents inside of spacecraft Faraday cage on or near critical circuitry, and RF noise.

  4. COMPACT EXCHANGERS FOR PHASE CHANGE

    Microsoft Academic Search

    Vishwas V. Wadekar

    Compact heat exchangers are being increasingly considered for duties involving phase change processes of boiling and condensation. In many cases such applications are completely new and no previous experience or information on exchanger performance is available. Understanding the thermal-hydraulic characteristics of flow passages of compact heat exchangers for phase change duties is therefore vitally important. Even for those compact heat

  5. Standard target for explosive charge testing

    SciTech Connect

    Regalbuto, J.A.

    1990-06-12

    This patent describes a method of testing an explosive charge. It comprises: detonating an explosive shaped charge in the proximity of a target comprising a molded article produced by admixed a quantity of phenolic resin with a particulate, the admixture being compacted in a mold to yield a product having a specific gravity in the range of from about 2.7 to about 2.8, the molded compacted mixture then being heated to an elevated temperature for a sufficient duration to form a target having uniform density and compression properties; measuring at least one feature of the penetration of the shaped charge on the target; determining the explosive capability of the shaped charge from the measured feature of the penetration.

  6. Compact Spreader Schemes

    SciTech Connect

    Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.

    2014-07-25

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  7. Compact Optical Correlators

    NASA Astrophysics Data System (ADS)

    Gregory, Don A.; Kirsch, James C.

    1989-02-01

    In the past 15 years, a dozen or so designs have been proposed for compact optical correlators. Of these, maybe one-third of them have actually been built and only a few of those tested. This paper will give an overview of some of the systems that have been built as well as mention some promising early and current designs that have not been built. The term compact, as used in the title of this paper, will be applied very loosely; to mean smaller than a laboratory size optical table. To date, only one correlator has been built and tested that actually can be called miniature. This softball size correlator was built by the Perkin-Elmer Corporation for the U. S. Army Missile Command at Redstone Arsenal, Alabama. More will be said about this correlator in following sections.

  8. Compact gas insulated transformer

    NASA Astrophysics Data System (ADS)

    1984-01-01

    The development of design and manufacturing technologies is described. A transformer which is more efficient, more compact, lower in weight and audible sound, nonflammable, which does not rely upon mineral oil insulation, and which is compatible with the gas insulated electrical system of the future is designed. Design prototypes in the 50 MVA-345 kV range are to be tested. The program provides for economic, environmental, and systems application assessments of the emergent technologies.

  9. Non-Compaction-Kardiomyopathie

    Microsoft Academic Search

    Heinrich Wieneke; Till Neumann; Frank Breuckmann; Peter Hunold; Jochen W. U. Fries; Olaf Dirsch; Raimund Erbel

    2005-01-01

    Zusammenfassung Die isolierte ventrikuläre Non-Compaction-Kardiomyopathie (INVM), die in der Literatur auch unter der Bezeichnung „spongy myocardium“ oder „left ventricular hypertrabeculation“ zu finden ist, zählt nach der WHO-Klassifikation zu den nicht klassifizierten Kardiomyopathien. Es handelt sich um eine angeborene Erkrankung des linksventrikulären Myokards, die nach heutiger Auffassung auf eine Störung der myokardialen Morphogenese zurückzuführen ist. Diese Störung, die sowohl sporadisch als

  10. Charge-pump voltage converter

    DOEpatents

    Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  11. Development of a repetitive compact torus injector

    NASA Astrophysics Data System (ADS)

    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. 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.

  12. Compact Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2004-01-01

    A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

  13. Compact slanted grating couplers

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Jiang, Jianhua; Nordin, Gregory P.

    2004-07-01

    We present a compact and efficient design for slanted grating couplers (SLGC's) to vertically connect fibers and planar waveguides without intermediate optics. The proposed SLGC employs a strong index modulated slanted grating. With the help of a genetic algorithm-based rigorous design tool, a 20 ?m-long SLGC with 80.1% input coupling efficiency has been optimized. A rigorous mode analysis reveals that the phase-matching condition and Bragg condition are satisfied simultaneously with respect to the fundamental leaky mode supported by the optimized SLGC.

  14. Eccentric Compact Object Mergers

    NASA Astrophysics Data System (ADS)

    East, William; Pretorius, Frans; Stephens, Branson

    2012-03-01

    Mergers of black holes and neutron stars are expected to be an important source of gravitational radiation for upcoming observatories. Such mergers are also a leading candidate for short gamma-ray burst progenitors and may be source for other electromagnetic counterparts. An interesting class of compact object binaries are those that form in dense stellar regions such as globular clusters and may merge with significant eccentricity. We present results from general-relativistic hydrodynamics simulations that are performed in order to explore the dynamics and possible observational signatures of such systems.

  15. Upgrading coke strength by a coal-blend-compaction process

    SciTech Connect

    Fun, F.; Brayton, W.E.; Shoenberger, R.W.

    1981-01-01

    In the continuing effort to upgrade the strength of coke made from available coal blends, US Steel is developing coal-blend compaction as an alternative method to coal preheating. In this process the coal blend is compacted to produce relatively weak compacted materials, which are subsequently degraded into controlled size fractions of intimately integrated particles of the multicomponent coal blend. The degraded blend particles are charged into conventional coke ovens for coking. Coal-blend-compaction tests conducted in the laboratory with coals from the Appalachian basin showed substantial improvement in coke strength. The encouraging laboratory results dictated a commerical scale test at US Steel's Gary Works. This plant test, in which more than 200 tons of coal blend was used, further confirmed the improvement in coke strength by the coal-blend-compaction process. Potential benefits of the process include (1) retrospective adaptation to existing coke batteries, (2) improved strength of coke from regular coal blends, (3) maintenance of same or higher coke strength with poor coal blends, and (4) economics that are competitive with or better than those of coal preheating. Continuing developments are being investigated in a compaction pilot plant and commercial coke ovens at US Steel's Clairton Works, mainly to establish engineering criteria and optimal controls for large-scale installations. 9 figures, 2 tables.

  16. Charge Challenge

    NSDL National Science Digital Library

    University of Kansas

    2006-01-01

    In this activity, learners explore how objects can have positive, negative, or neutral charges, which attract, repel and move between objects. Learners charge various materials and observe their interactions. Winter is an ideal time to perform these experiments (because there is less water vapor in the air); if it is humid, use a hair dryer to dry the objects, surfaces, and air around the work area.

  17. Charged black holes in two-dimensional string theory

    Microsoft Academic Search

    Michael D. McGuigan; Chiara R. Nappi; Scott A. Yost

    1991-01-01

    We discuss two dimensional string theories containing gauge elds, introduced either via coupling to open strings, in which case we get a Born-Infeld type action, or via heterotic compactication. The solutions of the modied background eld equations are charged black holes which exhibit interesting space time geometries. We also compute their masses and charges.

  18. Compaction of Titanium Powders

    SciTech Connect

    Stephen J. Gerdemann; Paul D. Jablonski

    2010-11-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 ?m, <75 ?m, and < 45 ?m; two different sizes of a hydride-dehydride [HDH] <75 ?m and < 45 ?m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  19. Compaction of Titanium Powders

    SciTech Connect

    Gerdemann, Stephen,J; Jablonski, Paul, J

    2011-05-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines<150 {micro}m,<75 {micro}m, and<45 {micro}m; two different sizes of a hydride-dehydride [HDH]<75 {micro}m and<45 {micro}m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  20. Charge and the topology of spacetime

    E-print Network

    Tammo Diemer; Mark J Hadley

    1999-09-02

    A new class of electrically charged wormholes is described in which the outer two sphere is not spanned by a compact coorientable hypersurface. These wormholes can therefore display net electric charge from the source free Maxwell's equation. This extends the work of Sorkin on non-space orientable manifolds, to spacetimes which do not admit a time orientation. The work is motivated by the suggestion that quantum theory can be explained by modelling elementary particles as regions of spacetime with non-trivial causal structure. The simplest example of an electrically charged spacetime carries a spherical symmetry.

  1. Compact vacuum insulation embodiments

    DOEpatents

    Benson, D.K.; Potter, T.F.

    1992-04-28

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point' or line' contacts with the metal wall sheets. In the case of monolithic spacers that form line' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included. 26 figs.

  2. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A. (Los Alamos, NM)

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  3. Compact acoustic refrigerator

    SciTech Connect

    Bennett, G.A.

    1991-12-31

    This invention is comprised of a compact acoustic refrigeration system that actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment.

  4. Compact vacuum insulation

    DOEpatents

    Benson, D.K.; Potter, T.F.

    1993-01-05

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  5. Compact reactor design automation

    NASA Technical Reports Server (NTRS)

    Nassersharif, Bahram; Gaeta, Michael J.

    1991-01-01

    A conceptual compact reactor design automation experiment was performed using the real-time expert system G2. The purpose of this experiment was to investigate the utility of an expert system in design; in particular, reactor design. The experiment consisted of the automation and integration of two design phases: reactor neutronic design and fuel pin design. The utility of this approach is shown using simple examples of formulating rules to ensure design parameter consistency between the two design phases. The ability of G2 to communicate with external programs even across networks provides the system with the capability of supplementing the knowledge processing features with conventional canned programs with possible applications for realistic iterative design tools.

  6. Multipurpose Compact Spectrometric Unit

    SciTech Connect

    Bocarov, Viktor; Cermak, Pavel; Mamedov, Fadahat; Stekl, Ivan [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, CZ-12800 Prague 2 (Czech Republic)

    2009-11-09

    A new standalone compact spectrometer was developed. The device consists of analog (peamplifier, amplifier) and digital parts. The digital part is based on the 160 MIPS Digital Signal Processor. It contains 20 Msps Flash-ADC, 1 MB RAM for spectra storage, 128 KB Flash/ROM for firmware storage, Real Time Clock and several voltage regulators providing the power for user peripherals (e.g. amplifier, temperature sensors, etc.). Spectrometer is connected with a notebook via high-speed USB 2.0 bus. The spectrometer is multipurpose device, which is planned to be used for measurements of Rn activities, energy of detected particles by CdTe pixel detector or for coincidence measurements.

  7. A Compact Solid State Detector for Small Angle Particle Tracking

    E-print Network

    S. Altieri; O. Barnaba; A. Braghieri; M. Cambiaghi; A. Lanza; T. Locatelli; A. Panzeri; P. Pedroni; T. Pinelli; P. Jennewein; M. Lang; I. Preobrazhensky; J. R. M. Annand; F. Sadiq

    1999-11-09

    MIDAS (MIcrostrip Detector Array System) is a compact silicon tracking telescope for charged particles emitted at small angles in intermediate energy photonuclear reactions. It was realized to increase the angular acceptance of the DAPHNE detector and used in an experimental program to check the Gerasimov-Drell-Hearn sum rule at the Mainz electron microtron, MAMI. MIDAS provides a trigger for charged hadrons, p/pi identification and particle tracking in the region 7 deg < theta < 16 deg. In this paper we present the main characteristics of MIDAS and its measured performances.

  8. Compact Linear Collider drive beam phase stabilization simulations

    NASA Astrophysics Data System (ADS)

    Gerbershagen, A.; Schulte, D.; Burrows, P. N.

    2015-04-01

    The drive beam phase stability is one of the critical feasibility issues of the Compact Linear Collider (CLIC) project. This paper presents a step-by-step analysis of the error propagation through the CLIC drive beam complex using realistic rf potential and beam loading amplitude functions for the drive and main beam accelerating structures. The impact of planned stabilization systems for drive beam bunch charge and longitudinal phase is simulated and the optimal specifications for such systems are calculated and discussed.

  9. Fractional statistics in three dimensions: Compact Maxwell-Higgs system

    SciTech Connect

    Fort, H.; Gambini, R. [Instituto de Fisica, Facultad de Ciencias, Tristan Narvaja 1674, 11200 Montevideo (Uruguay)] [Instituto de Fisica, Facultad de Ciencias, Tristan Narvaja 1674, 11200 Montevideo (Uruguay)

    1996-07-01

    We show that a (3+1)-dimensional system composed of an open magnetic vortex and an electrical point charge exhibits the phenomenon of Fermi-Bose transmutation. In order to provide the physical realization of this system we focus on the lattice compact scalar electrodynamics SQED{sub {ital c}} whose topological excitations are open Nielsen-Olesen strings with magnetic monopoles attached at their ends. {copyright} {ital 1996 The American Physical Society.}

  10. COMPACT MARX GENERATORS FOR THE GENERATION OF HIGH POWER MICROWAVES

    Microsoft Academic Search

    J. R. Mayes; W. J. Carey; W. C. Nunnally; L. Altgilbers; M. Kristiansen

    Traditional Marx generators have been primarily reserved for energy storage and pulse-charging sources. However, recent work 4 has demonstrated the Marx generator's effectiveness in delivering ultra-short impulses at very intense power levels. This paper discusses two very compact Marx generators capable of delivering voltage pulses of several hundred kV, durations of several nano-seconds to 10's of nanoseconds, and risetimes as

  11. Holding Charge

    NSDL National Science Digital Library

    Eric Muller

    1995-01-01

    In this trick, learners discover how to stick a straw to the palm of their hand, window door, or anywhere using static electricity. This activity introduces learners to negative and positive charges and shows how opposites attract. Note: this trick works best in low humidity (dry air).

  12. Charging characteristics of a solid insulator in vacuum under AC voltage excitation

    Microsoft Academic Search

    O. Yamamoto; S. Hamada; T. Fukuda; H. Omura

    2006-01-01

    We have investigated charging and flashover characteristics of a polymeric or glass insulator exposed to AC voltage in vacuum in order to develop compact and reliable high voltage VCBs (vacuum circuit breakers). This paper focuses on charging characteristics of a cylindrical model insulator. The charging of an insulator is investigated using an electrostatic probe that measures the electric field near

  13. 258 \\ENCYCLOPEDIA OF ELECTRICAL AND ELECTRONICS ENGINEERING" JOHN WILEY & SONS, INC Charge Injection Devices

    E-print Network

    Luryi, Serge

    diagram of a charge injection transistor. Carriers in the emitter layerare heatedby the sourceto drain Injection Devices Serge Luryi and Marco Mastrapasqua Abstract|The name "charge injection" describes contacted layers. Charge injection de- vices enable the implementation of compact optoelectronic gates

  14. A Compact Ring Design with Tunable Momentum Compaction

    SciTech Connect

    Sun, Y.; /SLAC; ,

    2012-05-17

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  15. Use of a BCD for compaction control 

    E-print Network

    Li, Yanfeng

    2005-11-01

    Compaction of soil is essential in the construction of highways, airports, buildings, and bridges. Typically compaction is controlled by measuring the dry density and the water content of the compacted soil and checking ...

  16. Collective Deceleration: Toward a Compact Beam Dump

    SciTech Connect

    Wu, H.-C.; /Munich, Max Planck Inst. Quantenopt.; Tajima, T.; Habs, D.; /Munich, Max Planck Inst. Quantenopt. /Munich U.; Chao, A.W.; /SLAC; Meyer-ter-Vehn, J.; /Munich, Max Planck Inst. Quantenopt.

    2011-11-28

    With the increasing development of laser accelerators, the electron energy is already beyond GeV and even higher in near future. Conventional beam dump based on ionization or radiation loss mechanism is cumbersome and costly, also has radiological hazards. We revisit the stopping power of high-energy charged particles in matter and discuss the associated problem of beam dump from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than the Bethe-Bloch and multiple electromagnetic cascades stopping length in solid. At the mean time, the tenuous density of the gas makes the radioactivation negligible. Such a compact and non-radioactivating beam dump works well for short and dense bunches, which is typically generated from laser wakefield accelerator.

  17. Compact toroid formation, compression, and acceleration

    SciTech Connect

    Degnan, J.H.; Peterkin, R.E. Jr.; Baca, G.P.; Beason, J.D.; Bell, D.E.; Dearborn, M.E.; Dietz, D.; Douglas, M.R.; Englert, S.E.; Englert, T.J.; Hackett, K.E.; Holmes, J.H.; Hussey, T.W.; Kiuttu, G.F.; Lehr, F.M.; Marklin, G.J.; Mullins, B.W.; Price, D.W.; Roderick, N.F.; Ruden, E.L.; Sovinec, C.R.; Turchi, P.J. (High Energy Plasma Division, Phillips Laboratory, Kirtland AFB, New Mexico 87117 (United States)); Bird, G.; Coffey, S.K.; Seiler, S.W. (Physical Sciences Inc., Alexandria, Virginia 22314 (United States)); Chen, Y.G.; Gale, D.; Graham, J.D.; Scott, M.; Sommars, W. (Maxwell Laboratories, Inc., Albuquerque, New Mexico 87106 (United States))

    1993-08-01

    Research on forming, compressing, and accelerating milligram-range compact toroids using a meter diameter, two-stage, puffed gas, magnetic field embedded coaxial plasma gun is described. The compact toroids that are studied are similar to spheromaks, but they are threaded by an inner conductor. This research effort, named MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation), is not a magnetic confinement fusion program like most spheromak efforts. Rather, the ultimate goal of the present program is to compress toroids to high mass density and magnetic field intensity, and to accelerate the toroids to high speed. There are a variety of applications for compressed, accelerated toroids including fast opening switches, x-radiation production, radio frequency (rf) compression, as well as charge-neutral ion beam and inertial confinement fusion studies. Experiments performed to date to form and accelerate toroids have been diagnosed with magnetic probe arrays, laser interferometry, time and space resolved optical spectroscopy, and fast photography. Parts of the experiment have been designed by, and experimental results are interpreted with, the help of two-dimensional (2-D), time-dependent magnetohydrodynamic (MHD) numerical simulations. When not driven by a second discharge, the toroids relax to a Woltjer--Taylor equilibrium state that compares favorably to the results of 2-D equilibrium calculations and to 2-D time-dependent MHD simulations. Current, voltage, and magnetic probe data from toroids that are driven by an acceleration discharge are compared to 2-D MHD and to circuit solver/slug model predictions. Results suggest that compact toroids are formed in 7--15 [mu]sec, and can be accelerated intact with material species the same as injected gas species and entrained mass [ge]1/2 the injected mass.

  18. Compact neutron generator

    DOEpatents

    Leung, Ka-Ngo; Lou, Tak Pui

    2005-03-22

    A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

  19. Laboratory compaction of cohesionless sands

    E-print Network

    Delphia, John Girard

    1998-01-01

    that if the soil is compacted to a low relative compaction the amount of settlement can be quite high. An example of the use of the settlement analysis is given to demonstrate this effect. This thesis is dedicated to my parents: John C. and Sally Delphia... of the soil, shape of the particles and the laboratory test method used. These factors will be INITIAL SOIL STATE Ww' V 1 Vw i Vv Vt Ws Vs COMPACTED SOIL STATE C W Vw Vt Ws Vs Vt )Vt Com acted Dr Unit Wei ht '7 = Ws/Vt Definitions Ws = weight...

  20. Compact fission counter for DANCE

    SciTech Connect

    Wu, C Y; Chyzh, A; Kwan, E; Henderson, R; Gostic, J; Carter, D; Bredeweg, T; Couture, A; Jandel, M; Ullmann, J

    2010-11-06

    The Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 BF{sub 2} crystals with equal solid-angle coverage. DANCE is a 4{pi} {gamma}-ray calorimeter and designed to study the neutron-capture reactions on small quantities of radioactive and rare stable nuclei. These reactions are important for the radiochemistry applications and modeling the element production in stars. The recognition of capture event is made by the summed {gamma}-ray energy which is equivalent of the reaction Q-value and unique for a given capture reaction. For a selective group of actinides, where the neutron-induced fission reaction competes favorably with the neutron capture reaction, additional signature is needed to distinguish between fission and capture {gamma} rays for the DANCE measurement. This can be accomplished by introducing a detector system to tag fission fragments and thus establish a unique signature for the fission event. Once this system is implemented, one has the opportunity to study not only the capture but also fission reactions. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to {alpha} particles, which is important for experiments with {alpha}-emitting actinides. Therefore, a PPAC is an ideal detector for experiments requiring a fast and clean trigger for fission. A PPAC with an ingenious design was fabricated in 2006 by integrating amplifiers into the target assembly. However, this counter was proved to be unsuitable for this application because of issues related to the stability of amplifiers and the ability to separate fission fragments from {alpha}'s. Therefore, a new design is needed. A LLNL proposal to develop a new PPAC for DANCE was funded by NA22 in FY09. The design goal is to minimize the mass for the proposed counter and still be able to maintain a stable operation under extreme radioactivity and the ability to separate fission fragments from {alpha}'s. In the following sections, the description is given for the design and performance of this new compact PPAC, for studying the neutron-induced reactions on actinides using DANCE at LANL.

  1. CHARGING AND COAGULATION OF DUST IN PROTOPLANETARY PLASMA ENVIRONMENTS

    SciTech Connect

    Matthews, L. S.; Land, V.; Hyde, T. W., E-mail: lorin_matthews@baylor.edu [Center for Astrophysics, Space Physics, and Engineering Research, Baylor University, Waco, TX 76798-7316 (United States)

    2012-01-01

    Combining a particle-particle, particle-cluster, and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in plasma environments relevant for protoplanetary disks have been investigated, including the effect of electron depletion in high dust density environments. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, and that cluster-cluster aggregation is significantly more effective than particle-cluster aggregation. Comparisons of the grain structure show that with increasing aggregate charge the compactness factor, {phi}{sub {sigma}}, decreases and has a narrower distribution, indicating a fluffier structure. Neutral aggregates are more compact, with larger {phi}{sub {sigma}}, and exhibit a larger variation in fluffiness. Overall, increased aggregate charge leads to larger, fluffier, and more massive aggregates.

  2. MESOSCALE SIMULATIONS OF POWDER COMPACTION

    SciTech Connect

    Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore CA 94551 (United States)

    2009-12-28

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  3. New considerations for compact cyclotrons

    E-print Network

    Marshall, Eric S. (Eric Scott)

    2012-01-01

    A compact cyclotron built with superconducting magnets could be a transformative solution to many scientific problems facing the defense, medical, and energy industries today. This thesis discusses three potential applications ...

  4. Photon and neutrino redshift in the field of braneworld compact stars

    SciTech Connect

    Hladík, Jan; Stuchlík, Zden?k, E-mail: jan.hladik@fpf.slu.cz, E-mail: zdenek.stuchlik@fpf.slu.cz [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezrucovo nám. 13, CZ-746 01 Opava (Czech Republic)

    2011-07-01

    We study gravitational redshift of photons and neutrinos radiated by the braneworld neutron or quark stars that are considered in the framework of the simple model of the internal spacetime with uniform distribution of energy density, and the external spacetime described by the Reissner-Nordström geometry characterized by the braneworld ''tidal'' charge b. For negative tidal charges, the external spacetime is of the black-hole type, while for positive tidal charges, the external spacetime can be of both black-hole and naked-singularity type. We consider also extremely compact stars allowing existence of trapped null geodesics in their interior. We assume radiation of photons from the surface at radius R, neutrinos from the whole compact star interior, and their motion along radial null geodesics of the spacetime. In dependency on the compact stars parameters b and R, the photon surface redshift is related to the range of the neutrino internal redshift and the signatures of the tidal charge and possible existence of extremely compact stars are discussed. When both surface (photon) and internal (neutrino) redshift are given by observations, both compact star parameters R and b can be determined in the framework of our simple model.

  5. A compact HTS filter subsystem

    Microsoft Academic Search

    K. Murayama; Y. Maeda; Y. Hiratsuka; F. Imai; K. Y. Kang

    2001-01-01

    Summary form only given, as follows. We describe a compact, long-life High-Temperature Superconducting (HTS) filter subsystem for mobile telecommunication base stations. This system consists mainly of a HTS filter and a low-noise amplifier (LNA), which are cooled by a Stirling pulse tube type cryocooler. The cooler is compact and has a service life of more than 5 years, theoretically, because

  6. Coalescence of compact binary stars with a quark star component

    NASA Astrophysics Data System (ADS)

    Koshy, Sam

    Coalescing compact star binaries are among the most promising sources for the next generation of gravitational detectors. Accurate theoretical waveform templates are required to extract their gravitational wave signal from noisy data and it is expected that about 10 mergers per year (or more) of such binaries will be found by these upcoming detectors. If these binaries tidally lock/synchronize, where synchronization is facilitated by a large viscosity for the stellar fluid, then their inspiral is accelerated. This will result in a phase mismatch between the signal and templates and failure to include these contributions from tidal synchronization can hamper detection. Bildsten and Cutler in 1992 studied tidal synchronization in neutron star-neutron star and black hole-neutron star binaries, and found that the viscosity of the neutron star was too small Here we study the same effect but in binaries with a quark star component. What makes quark stars different from neutron stars is that (a) quark matter can potentially have large viscosities and (b) unlike neutron stars, quark stars do not have a theoretical lower mass limit. These two features imply that quark stars could tidally synchronize under some extreme conditions on certain parameters, unlike neutron stars which never synchronize. Thus, the gravitational wave signal can be used to detect and differentiate quark stars from ordinary neutron stars. One important feature of inspiraling binaries during the final stages of the inspiral is the possibility of mass transfer, which can further alter the expected gravitational wave signal Therefore, we study the conditions necessary for stable mass transfer in the neutron star-quark star binary system and determine that the most likely scenario at this stage is unstable mass transfer from the neutron star to the quark star. Finally, we examine the fate of the binary system after tidal synchronization is achieved. We propose a variational study of tidal synchronization based on the work of Lai et al. in 1994, which accounts for deformations of the component stars of the neutron star-quark star binary. Using a newly devised polytropic equation of state for quark stars, we expect the stars to remain tidally synchronized although more sophisticated numerics will be required to prove this. Our main conclusion is that gravitational waves can discriminate between neutron star-neutron star binaries and neutron star-quark star binaries, but only if one assumes an extreme selection of theoretical parameters. In practice, this distinction may therefore be very difficult to achieve.

  7. Six host range variants of the xenotropic/polytropic gammaretroviruses define determinants for entry in the XPR1 cell surface receptor

    PubMed Central

    Yan, Yuhe; Liu, Qingping; Kozak, Christine A

    2009-01-01

    Background The evolutionary interactions between retroviruses and their receptors result in adaptive selection of restriction variants that can allow natural populations to evade retrovirus infection. The mouse xenotropic/polytropic (X/PMV) gammaretroviruses rely on the XPR1 cell surface receptor for entry into host cells, and polymorphic variants of this receptor have been identified in different rodent species. Results We screened a panel of X/PMVs for infectivity on rodent cells carrying 6 different XPR1 receptor variants. The X/PMVs included 5 well-characterized laboratory and wild mouse virus isolates as well as a novel cytopathic XMV-related virus, termed Cz524, isolated from an Eastern European wild mouse-derived strain, and XMRV, a xenotropic-like virus isolated from human prostate cancer. The 7 viruses define 6 distinct tropisms. Cz524 and another wild mouse isolate, CasE#1, have unique species tropisms. Among the PMVs, one Friend isolate is restricted by rat cells. Among the XMVs, two isolates, XMRV and AKR6, differ from other XMVs in their PMV-like restriction in hamster cells. We generated a set of Xpr1 mutants and chimeras, and identified critical amino acids in two extracellular loops (ECLs) that mediate entry of these different viruses, including 3 residues in ECL3 that are involved in PMV entry (E500, T507, and V508) and can also influence infectivity by AKR6 and Cz524. Conclusion We used a set of natural variants and mutants of Xpr1 to define 6 distinct host range variants among naturally occurring X/PMVs (2 XMV variants, 2 PMVs, 2 different wild mouse variants). We identified critical amino acids in XPR1 that mediate entry of these viruses. These gammaretroviruses and their XPR1 receptor are thus highly functionally polymorphic, a consequence of the evolutionary pressures that favor both host resistance and virus escape mutants. This variation accounts for multiple naturally occurring virus resistance phenotypes and perhaps contributes to the widespread distribution of these viruses in rodent and non-rodent species. PMID:19811656

  8. Soil Compaction College of Agricultural Sciences

    E-print Network

    Kaye, Jason P.

    Effects of Soil Compaction College of Agricultural Sciences Agricultural Research and Cooperative Extension #12;2 EFFECTS OF SOIL COMPACTION Effects of Soil Compaction INTRODUCTION Soil compaction is the reduction of soil volume due to external factors; this reduction lowers soil productivity and environmental

  9. Compact Optoelectronic Compass

    NASA Technical Reports Server (NTRS)

    Christian, Carl

    2004-01-01

    A compact optoelectronic sensor unit measures the apparent motion of the Sun across the sky. The data acquired by this chip are processed in an external processor to estimate the relative orientation of the axis of rotation of the Earth. Hence, the combination of this chip and the external processor finds the direction of true North relative to the chip: in other words, the combination acts as a solar compass. If the compass is further combined with a clock, then the combination can be used to establish a threeaxis inertial coordinate system. If, in addition, an auxiliary sensor measures the local vertical direction, then the resulting system can determine the geographic position. This chip and the software used in the processor are based mostly on the same design and operation as those of the unit described in Micro Sun Sensor for Spacecraft (NPO-30867) elsewhere in this issue of NASA Tech Briefs. Like the unit described in that article, this unit includes a small multiple-pinhole camera comprising a micromachined mask containing a rectangular array of microscopic pinholes mounted a short distance in front of an image detector of the active-pixel sensor (APS) type (see figure). Further as in the other unit, the digitized output of the APS in this chip is processed to compute the centroids of the pinhole Sun images on the APS. Then the direction to the Sun, relative to the compass chip, is computed from the positions of the centroids (just like a sundial). In the operation of this chip, one is interested not only in the instantaneous direction to the Sun but also in the apparent path traced out by the direction to the Sun as a result of rotation of the Earth during an observation interval (during which the Sun sensor must remain stationary with respect to the Earth). The apparent path of the Sun across the sky is projected on a sphere. The axis of rotation of the Earth lies at the center of the projected circle on the sphere surface. Hence, true North (not magnetic North), relative to the chip, can be estimated from paths of the Sun images across the APS. In a test, this solar compass has been found to yield a coarse estimate of the North (within tens of degrees) in an observation time of about ten minutes. As expected, the accuracy was found to increase with observation time: after a few hours, the estimated direction of the rotation axis becomes accurate to within a small fraction of a degree.

  10. The regular-locally-compact coreflection of a stably locally compact locale

    E-print Network

    Escardó, Martín

    The regular-locally-compact coreflection of a stably locally compact locale locally compact locales and perfect maps as a coref* *lective subcategory of the category of stably locally compact locales and perfect maps, (ii) the category of compact regular locales and continuous maps

  11. Compact orthogonal NMR field sensor

    DOEpatents

    Gerald, II, Rex E. (Brookfield, IL); Rathke, Jerome W. (Homer Glen, IL)

    2009-02-03

    A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

  12. Weakly Charged Cationic Nanoparticles Induce DNA Bending and Strand Separation

    SciTech Connect

    Railsback, Justin [North Carolina State University; Singh, Abhishek [North Carolina State University; Pearce, Ryan [North Carolina State University; McKnight, Timothy E [ORNL; Collazo, Ramon [North Carolina State University; Sitar, Zlatko [ORNL; Yingling, Yaroslava [North Carolina State University; Melechko, Anatoli Vasilievich [ORNL

    2012-01-01

    The understanding of interactions between double stranded (ds) DNA and charged nanoparticles will have a broad bearing on many important applications from drug delivery [ 1 4 ] to DNAtemplated metallization. [ 5 , 6 ] Cationic nanoparticles (NPs) can bind to DNA, a negatively charged molecule, through a combination of electrostatic attraction, groove binding, and intercalation. Such binding events induce changes in the conformation of a DNA strand. In nature, DNA wraps around a cylindrical protein assembly (diameter and height of 6 nm) [ 7 ] with an 220 positive charge, [ 8 ] creating the complex known as chromatin. Wrapping and bending of DNA has also been achieved in the laboratory through the binding of highly charged species such as molecular assemblies, [ 9 , 10 ] cationic dendrimers, [ 11 , 12 ] and nanoparticles. [ 13 15 ] The charge of a nanoparticle plays a crucial role in its ability to induce DNA structural changes. If a nanoparticle has a highly positive surface charge density, the DNA is likely to wrap and bend upon binding to the nanoparticle [ 13 ] (as in the case of chromatin). On the other hand, if a nanoparticle is weakly charged it will not induce dsDNA compaction. [ 9 , 10 , 15 ] Consequently, there is a transition zone from extended to compact DNA conformations which depends on the chemical nature of the nanoparticle and occurs for polycations with charges between 5 and 10. [ 9 ] While the interactions between highly charged NPs and DNA have been extensively studied, the processes that occur within the transition zone are less explored.

  13. Physical Fourier encoding and compacting of optical data

    NASA Astrophysics Data System (ADS)

    Logofatu, Petre C.; Garoi, Florin; Damian, Victor; Udrea, Cristian

    2015-02-01

    A simple way to make physical encoding of data is to use some common Fourier optics tools, like lenses and some more sophisticated ones like a digital matrix detector (CCD, Charged Coupled Devices), as in Fig. 1. Except now the encoding and the compacting of the data is not made using Hadamard transform but a Fourier transform, which has less compacting power. There is however the big advantage of physically encrypting the data instead of manually or digitally doing the computation. The input data may be anything, a note, a picture, a diagram, anything at all. It may come at a moment notice and does not require any special preparation on the part of the operator. One can accomplish real-time encoding. It may require, however that the message data to be made available in a specific format, independent of the contents of the message. For instance it may have to be inscribed on a transparency and to have certain dimensions.

  14. A Compact Pulsed Power Generator for Capillary Pinch Experiments

    SciTech Connect

    Shukla, R.; Shyam, A. [Institute for Plasma Research, Near Indira Bridge, Bhat Village, Gandhinagar Gujarat 382428 (India)

    2006-01-05

    A compact pulsed power system is designed for conducting capillary pinch experiments for production of coherent electromagnetic radiations. The reported Pulsed power system is made very compact as well as portable by using solid dielectric pulse forming line. The system consists of a tesla transformer, which is of helical secondary and cylindrical-sheet single-turn primary. Tesla charges a pulse forming line made of cascade of 50 ohm transition lines, which are of high wattage as well as high voltage ratings under pulsed operation. The net impedance of this cable cascade is such that it is matched for a designed load, which is designed to operate at 250kV for 100ns pulse duration.

  15. Effect of {zeta} potential on the strength of compacted coal logs

    SciTech Connect

    Liu, H.; Lin, Y.; Marrero, T.R. [Univ. of Missouri, Columbia, MO (United States). Capsule Pipeline Research Center] [Univ. of Missouri, Columbia, MO (United States). Capsule Pipeline Research Center

    1996-01-01

    Coal can be compacted into solid cylinders called coal logs to facilitate handling and transportation. It is hypothesized and proved experimentally herein that by altering the {zeta} potential of coal to achieve the isoelectric point, the strength and abrasion resistance of compacted coal logs can be significantly improved. Experimental data providing the evidence are reported herein. It is theorized that by zeroing the {zeta} potential of the coal, the charges on coal particles are neutralized, and the electrostatic repelling force between coal particles containing like charges is eliminated. This brings the particles closer together with less compaction pressure and force. This method to improve coal agglomerate strength may be applicable to briquetting and pelletizing of fine particles of materials wetted by water.

  16. Estimation of surface charges on dielectric materials for high power rf windows

    NASA Astrophysics Data System (ADS)

    Michizono, Shinichiro; Saito, Yoshio; Suharyanto; Yamano, Yasushi; Kobayashi, Shinichi

    2009-11-01

    The surface discharges observed at rf windows and vacuum circuit breakers (VCBs) are one of the difficulties faced when developing high-power rf windows or compact VCBs. The surface discharge is considered to take place due to the release of the surface charges. Despite the importance of the surface charging/discharging, these phenomena have not been well evaluated. In this paper, the surface charges are estimated using the multipulse method, where electron beam irradiates a sample up to the saturation condition of surface charges. The amount of surface charges on alumina and TiN coated alumina are compared and the charging mechanism is discussed.

  17. Mesoscale Simulations of Power Compaction

    SciTech Connect

    Lomov, I; Fujino, D; Antoun, T; Liu, B

    2009-08-06

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

  18. Compact color schlieren optical system

    NASA Technical Reports Server (NTRS)

    Buchele, Donald R.; Griffin, Devon W.

    1993-01-01

    A compact optical system for use with rainbow schlieren deflectometry is described. Both halves of the optical system consist of well-corrected telescopes whose refractive elements are all from manufacturer's stock catalogs, with the reflective primary being a spherical surface. As a result, the system is relatively easy to construct and meets the requirement of long focal length for quantitative rainbow schlieren measurements.

  19. The Compact Project: Final Report.

    ERIC Educational Resources Information Center

    National Alliance of Business, Inc., Washington, DC.

    The National Alliance of Business (NAB) surveyed the 12 sites that participated in the Compact Project to develop and implement programs of business-education collaboration. NAB studied start-up activities, key players, conditions for collaboration, accomplishments, challenges, and future plans. Program outcomes indicated that building successful…

  20. Higgsless superconductivity from topological defects in compact BF terms

    NASA Astrophysics Data System (ADS)

    Diamantini, M. Cristina; Trugenberger, Carlo A.

    2015-02-01

    We present a new Higgsless model of superconductivity, inspired from anyon superconductivity but P- and T-invariant and generalisable to any dimension. While the original anyon superconductivity mechanism was based on incompressible quantum Hall fluids as average field states, our mechanism involves topological insulators as average field states. In D space dimensions it involves a (D - 1)-form fictitious pseudovector gauge field which originates from the condensation of topological defects in compact low-energy effective BF theories. In the average field approximation, the corresponding uniform emergent charge creates a gap for the (D - 2)-dimensional branes via the Magnus force, the dual of the Lorentz force. One particular combination of intrinsic and emergent charge fluctuations that leaves the total charge distribution invariant constitutes an isolated gapless mode leading to superfluidity. The remaining massive modes organise themselves into a D-dimensional charged, massive vector. There is no massive Higgs scalar as there is no local order parameter. When electromagnetism is switched on, the photon acquires mass by the topological BF mechanism. Although the charge of the gapless mode (2) and the topological order (4) are the same as those of the standard Higgs model, the two models of superconductivity are clearly different since the origins of the gap, reflected in the high-energy sectors are totally different. In 2D this type of superconductivity is explicitly realised as global superconductivity in Josephson junction arrays. In 3D this model predicts a possible phase transition from topological insulators to Higgsless superconductors.

  1. Small Anion with Higher Valency Retards the Compaction of DNA in the Presence of Multivalent Cation

    PubMed Central

    Saito, Takuya; Iwaki, Takafumi; Yoshikawa, Kenichi

    2009-01-01

    It has been established that, upon the addition of multivalent cations, long DNA chains in an aqueous solution exhibit a remarkable discrete transition from a coil state to a compact state at the level of a single chain. In this study, we investigated the polyelectrolyte nature of DNA with the experimental methodology of single-DNA observation, and provide a theoretical interpretation. We examined the effects of co-ions with different valencies (Cl?, SO42?, PO43?) on DNA compaction. As a result, we found that co-ions with a greater valency induce the coil state rather than the compact state. Based on a simple model with mean-field approximation that considered ion pairing, we show how the increase in entropy of small ions contributes to the stability of the compact state, by overcoming entropic penalties such as elastic confinement of the chain and a decrease in the translational freedom of counterions accompanied by charge neutralization. PMID:19186143

  2. 7 CFR 51.572 - Compact.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 FRESH FRUITS, VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION...CERTIFICATION, AND STANDARDS) United States Standards for Celery Definitions § 51.572 Compact. Compact means that the...

  3. 7 CFR 51.582 - Fairly compact.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 FRESH FRUITS, VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION...CERTIFICATION, AND STANDARDS) United States Standards for Celery Definitions § 51.582 Fairly compact. Fairly compact means...

  4. Technology of compact fusion-reactor concepts

    Microsoft Academic Search

    R. A. Krakowski; J. E. Glancy; A. E. Dabiri

    1982-01-01

    An identification of future engineering needs of compact, high-power-density approaches to fusion power is presented. After describing a rationale for the compact approach and a number of compact fusion reactors, key technology needs are assessed relative to the similar needs of the conventional tokamak in order to emphasize differences in required technology with respect to the well-documented mainline approaches.

  5. The technology of compact fusion reactor concepts

    Microsoft Academic Search

    R. A. Krakowski; A. E. Dabiri; J. E. Glancy

    1983-01-01

    An identification of future engineering needs of compact high-power-density approaches to fusion power is presented. After describing a rationale for the compact approach and a number of compact fusion reactors, key technology needs are assessed relative to the similar needs of the conventional tokamak in order to emphasize differences in required technology with respect to the well-documented mainline approaches.

  6. The regular-locally-compact coreflection of a stably locally compact locale

    E-print Network

    Escardó, Martín

    The regular-locally-compact coreflection of a stably locally compact locale Mart´in H¨otzel Escard as the patch frame. We show that the patch construction exhibits (i) the category of regular locally compact locales and perfect maps as a coreflective subcategory of the category of stably locally compact locales

  7. Electron Strippers for Compact Neutron Generators

    SciTech Connect

    Terai, K.; Tanaka, N.; Kisaki, M.; Tsugawa, K.; Okamoto, A.; Kitajima, S.; Sasao, M. [Graduate school of Engineering, Tohoku University, Aoba, Sendai, Miyagi 980-8579 (Japan); Takeno, T. [Tohoku University International Advanced Research and Education Organization, Aoba, Sendai, Miyagi 980-8578 (Japan); Antolak, A. J. [Sandia National Laboratories, Livermore, California 94550 (United States); Leung, K. N. [Lawrence Berkeley National Laboratory and Nuclear Engineering Dept., University of California, Berkeley (United States); Wada, M. [Doshisha University, Kyotanabe, Kyoto, 610-0321 (Japan)

    2011-09-26

    The next generation of compact tandem-type DD or DT neutron generators requires a robust electron stripper with high charge exchange efficiency. In this study, stripping foils of various types were tested, and the H{sup -} to H{sup +} conversion efficiency, endurance to the heat load, and durability were investigated in terms of suitability in the tandem-type neutron generator. In the experiments, a H{sup -} beam was accelerated to about 180 keV, passes through a stripping foil, and produces a mixed beam of H{sup -}, H{sup 0}, and H{sup +}. These ions were separated by an electric field, and detected by a movable Faraday cup to determine the conversion efficiency. The experimental results using thin foils of diamond-like carbon, gold, and carbon nano-tubes revealed issues on the robustness. As a new concept, a H{sup -} beam was injected onto a metal surface with an oblique angle, and reflected H{sup +} ions are detected. It was found that the conversion efficiency, H{sup +} fraction in the reflected particles, depends on the surface condition, with the maximum value of about 90%.

  8. Characteristics of solid-target charge-exchange analyzers for energetic ion diagnostics on tokamaks

    SciTech Connect

    Beiersdorfer, P.; Roquemore, A.L.; Kaita, R.

    1987-05-01

    Compact electrostatic charge-exchange analyzers have been constructed for installation in areas of high magnetic fields and restricted access near tokamak fusion devices. The analyzers employed carbon stripping foils, and have been calibrated for proton energies between 1 and 70 keV. They have been successfully used to study charge-exchange losses in auxiliary-heated tokamak plasmas.

  9. Estimation of surface charges on dielectric materials for high power rf windows

    Microsoft Academic Search

    Shinichiro Michizono; Yoshio Saito; Suharyanto; Yasushi Yamano; Shinichi Kobayashi

    2009-01-01

    The surface discharges observed at rf windows and vacuum circuit breakers (VCBs) are one of the difficulties faced when developing high-power rf windows or compact VCBs. The surface discharge is considered to take place due to the release of the surface charges. Despite the importance of the surface charging\\/discharging, these phenomena have not been well evaluated. In this paper, the

  10. Compact lanthanum hexaboride hollow cathode.

    PubMed

    Goebel, Dan M; Watkins, Ronald M

    2010-08-01

    A compact lanthanum hexaboride hollow cathode has been developed for space applications where size and mass are important and research and industrial applications where access for implementation might be limited. The cathode design features a refractory metal cathode tube that is easily manufactured, mechanically captured orifice and end plates to eliminate expensive e-beam welding, graphite sleeves to provide a diffusion boundary to protect the LaB6 insert from chemical reactions with the refractory metal tube, and several heater designs to provide long life. The compact LaB(6) hollow cathode assembly including emitter, support tube, heater, and keeper electrode is less than 2 cm in diameter and has been fabricated in lengths of 6-15 cm for different applications. The cathode has been operated continuously at discharge currents of 5-60 A in xenon. Slightly larger diameter versions of this design have operated at up to 100 A of discharge current. PMID:20815605

  11. Shock Response and Explosive Launch of Compacted Reactive Material

    NASA Astrophysics Data System (ADS)

    Molitoris, John; Gash, Alexander; Garza, Raul; Gagliardi, Franco; Tringe, Joseph; Batteux, Jan; Souers, P.; HEAF Team

    2013-06-01

    We have performed a series of experiments investigating the detailed dynamic response of compacted reactive material to shock and blast. Here a granular reactive formulation (Fe2O3/Al based thermite) was pressed into a solid cylinder of material and mated to a high-explosive charge of the same diameter. Detonation of the charge transmitted a shock wave to the thermite cylinder and imparted momentum launching it in the direction of the detonation. High-resolution time sequence radiography was used to image the dynamic response of the thermite. This technique allowed a detailed investigation of material deformation in addition to changes in the internal structure and indications of reactivity. The effect of variations in the initial density of the pressed thermite was also examined. We find that these pressed thermites behave much like solid metals during shock transit, then respond much differently. We have performed a series of experiments investigating the detailed dynamic response of compacted reactive material to shock and blast. Here a granular reactive formulation (Fe2O3/Al based thermite) was pressed into a solid cylinder of material and mated to a high-explosive charge of the same diameter. Detonation of the charge transmitted a shock wave to the thermite cylinder and imparted momentum launching it in the direction of the detonation. High-resolution time sequence radiography was used to image the dynamic response of the thermite. This technique allowed a detailed investigation of material deformation in addition to changes in the internal structure and indications of reactivity. The effect of variations in the initial density of the pressed thermite was also examined. We find that these pressed thermites behave much like solid metals during shock transit, then respond much differently. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  12. Compact Color Schlieren Optical System

    NASA Technical Reports Server (NTRS)

    Buchele, Donald R.; Griffin, Devon W.

    1996-01-01

    Compact, rugged optical system developed for use in rainbow schlieren deflectometry. Features unobscured telescope with focal-length/aperture-width ratio of 30. Made of carefully selected but relatively inexpensive parts. All of lenses stock items. By-product of design is optical system with loose tolerances on interlens spacing. One of resulting advantages, insensitivity to errors in fabrication of optomechanical mounts. Another advantage is ability to compensate for some of unit-to-unit variations inherent in stock lenses.

  13. Pattern diversity compact patch antenna

    Microsoft Academic Search

    M. S. Ruiz Palacios; M. J. Martinez Silva

    2010-01-01

    Diversity is a required property for antennas in Multiple Input-Multiple Output (MIMO) systems. In this paper a pattern diversity antenna is presented for operation in the 2.4 band of IEEE 802.11n WLAN MIMO standard. This compact antenna is formed by two shorted air substrate patch antennas located back to back in order to produce two lobes oriented in different directions.

  14. Compact integrated silica wavelength filters

    Microsoft Academic Search

    Christopher N. Morgan; Siyuan Yu; Richard V. Penty; Ian H. White

    2002-01-01

    The realization of compact low-loss wavelength filters using two-dimensional integrated optics (2DIO) in a silica-on-silica material system is reported. Two designs suitable for data-communications applications are reported: a 4 × 4 channel 6.4-nm channel wavelength spacing device and an 8 × 8 channel 3.2-nm channel wavelength spacing device. The devices are fabricated in one deep etch step, and after cleaving

  15. Compact magnetic energy storage module

    DOEpatents

    Prueitt, M.L.

    1994-12-20

    A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.

  16. Compact hybrid Si microring lasers

    Microsoft Academic Search

    Di Liang; John E. Bowers; Marco Fiorentino; Raymond G. Beausoleil

    2010-01-01

    In this paper we review the recent progress in developing compact microring lasers on the hybrid silicon platform. A simplified self-aligned process is used to fabricate devices as small as 15 mum in diameter. The optically-pumped, continuous wave (cw) devices show low threshold carrier density, comparable to the carrier density to reach material transparency. In the electrically-pumped lasers, the short

  17. Optimizing compact Marx generator networks

    Microsoft Academic Search

    C. Jerald Buchenauer; I. MARX GENERATORS DRIVING; RESISTIVE LOADS

    2009-01-01

    Compact linear Marx generators are frequently constructed in close-fitting metallic housings. The parasitic capacitance formed between the enclosure and Marx components can substantially exceed the inner-stage capacitance and play an important role in the Marx network performance. This capacitance and the inner-stage inductance form the components of a lumped-constant transmission line, which facilitates proper sequential firing of the spark switches.

  18. Thixoforming of Stellite Powder Compacts

    NASA Astrophysics Data System (ADS)

    Hogg, S. C.; Atkinson, H. V.; Kapranos, P.

    2007-04-01

    Thixoforming involves processing metallic alloys in the semi-solid state. The process requires the microstructure to be spheroidal when part-solid and part-liquid i.e. to consist of solid spheroids surrounded by liquid. The aim of this work was to investigate whether powder compacts can be used as feedstock for thixoforming and whether the consolidating pressure in the thixoformer can be used to remove porosity from the compact. The powder compacts were made from stellite 6 and stellite 21 alloys, cobalt-based alloys widely used for e.g. manufacturing prostheses. Isothermal heat treatments of small samples in the consolidated state showed the optimum thixoforming temperature to be in the range 1340°C-1350°C for both materials. The alloys were thixoformed into graphite dies and flowed easily to fill the die. Porosity in the thixoformed components was lower than in the starting material. Hardness values at various positions along the radius of the thixoformed demonstrator component were above the specification for both alloys.

  19. Compaction Waves in Granular HMX

    SciTech Connect

    E. Kober; R. Menikoff

    1999-01-01

    Piston driven compaction waves in granular HMX are simulated with a two-dimensional continuum mechanics code in which individual grains are resolved. The constitutive properties of the grains are modeled with a hydrostatic pressure and a simple elastic-plastic model for the shear stress. Parameters are chosen to correspond to inert HMX. For a tightly packed random grain distribution (with initial porosity of 19%) we varied the piston velocity to obtain weak partly compacted waves and stronger fully compacted waves. The average stress and wave speed are compatible with the porous Hugoniot locus for uni- axial strain. However, the heterogeneities give rise to stress concentrations, which lead to localized plastic flow. For weak waves, plastic deformation is the dominant dissipative mechanism and leads to dispersed waves that spread out in time. In addition to dispersion, the granular heterogeneities give rise to subgrain spatial variation in the thermodynamic variables. The peaks in the temperature fluctuations, known as hot spots, are in the range such that they are the critical factor for initiation sensitivity.

  20. A compact LED-based module for DNA capillary electrophoresis

    NASA Astrophysics Data System (ADS)

    Hurth, C.; Lenigk, R.; Zenhausern, F.

    2008-11-01

    A setup consisting of a bifurcated optical fiber made from high-transmission fused-silica cores with relatively high numerical apertures (NA=0.22), high-power cyan light-emitting diodes (LEDs) and Peltier cooling elements controlled by a proportional-integrative-derivative (PID) module is introduced to replace bulky, power- consuming lasers conventionally used in laser induced fluorescence (LIF) microchip capillary electrophoresis (?CE). The output fiber beam size, divergence, power distribution and power stability over time are documented. A modified epifluorescence microscope arrangement is used in conjunction with a compact fixed spectrometer aligned with a cooled charge-coupled device (CCD) camera for added sensitivity. Fluorescent dyes such as fluorescein, 6-carboxyfluorescein (6-FAM) and rhodamine B can be detected in cyclic olefin copolymer (COC) and glass microchannels at submicromolar levels. A single-stranded DNA oligonucleotide (10-mer) labeled with 6-FAM is also detected with reasonable signal-to-noise ratio when electrophoretically migrated at 100 V/cm. The compact LED excitation system presented herein will allow using capillary electrophoresis for DNA detection in compact mobile devices.

  1. Battery charging system

    Microsoft Academic Search

    Hignutt

    1986-01-01

    This patent describes a battery charging system with which in combination with an AC voltage source, a charging circuit of storage batteries is interconnected in series at intermediate junctions between end terminals of opposite polarity. The charging circuit has voltage converters respectively connected to the batteries and switching control operatively connected to the voltage converters for controlling the charging of

  2. Charge and Carry

    NSDL National Science Digital Library

    The Exploratorium

    2012-06-26

    In this activity about electricity, learners produce a spark that they can feel, see, and hear. Learners rub a Styrofoam plate with wool to give it an electric charge. Then, they use the charged Styrofoam to charge an aluminum pie pan. Essentially, learners build an electrophorus (Greek for "charge carrier"). This resource also contains instructions on how to build a large charge carrier called a "Leyden Jar" using a plastic film can.

  3. Compaction of Space Mission Wastes

    NASA Technical Reports Server (NTRS)

    Fisher, John; Pisharody, Suresh; Wignarajah, K.

    2004-01-01

    The current solid waste management system employed on the International Space Station (ISS) consists of compaction, storage, and disposal. Wastes such plastic food packaging and trash are compacted manually and wrapped in duct tape footballs by the astronauts. Much of the waste is simply loaded either into the empty Russian Progress vehicle for destruction on reentry or into Shuttle for return to Earth. This manual method is wasteful of crew time and does not transition well to far term missions. Different wastes onboard spacecraft vary considerably in their characteristics and in the appropriate method of management. In advanced life support systems for far term missions, recovery of resources such as water from the wastes becomes important. However waste such as plastic food packaging, which constitutes a large fraction of solid waste (roughly 21% on ISS, more on long duration missions), contains minimal recoverable resource. The appropriate management of plastic waste is waste stabilization and volume minimization rather than resource recovery. This paper describes work that has begun at Ames Research Center on development of a heat melt compactor that can be used on near term and future missions, that can minimize crew interaction, and that can handle wastes with a significant plastic composition. The heat melt compactor takes advantage of the low melting point of plastics to compact plastic materials using a combination of heat and pressure. The US Navy has demonstrated successful development of a similar unit for shipboard application. Ames is building upon the basic approach demonstrated by the Navy to develop an advanced heat melt type compactor for space mission type wastes.

  4. Isometric Immersions and Compensated Compactness

    NASA Astrophysics Data System (ADS)

    Chen, Gui-Qiang; Slemrod, Marshall; Wang, Dehua

    2010-03-01

    A fundamental problem in differential geometry is to characterize intrinsic metrics on a two-dimensional Riemannian manifold {{mathcal M}^2} which can be realized as isometric immersions into {mathbb{R}^3}. This problem can be formulated as initial and/or boundary value problems for a system of nonlinear partial differential equations of mixed elliptic-hyperbolic type whose mathematical theory is largely incomplete. In this paper, we develop a general approach, which combines a fluid dynamic formulation of balance laws for the Gauss-Codazzi system with a compensated compactness framework, to deal with the initial and/or boundary value problems for isometric immersions in {mathbb{R}^3}. The compensated compactness framework formed here is a natural formulation to ensure the weak continuity of the Gauss-Codazzi system for approximate solutions, which yields the isometric realization of two-dimensional surfaces in {mathbb{R}^3}. As a first application of this approach, we study the isometric immersion problem for two-dimensional Riemannian manifolds with strictly negative Gauss curvature. We prove that there exists a C 1, 1 isometric immersion of the two-dimensional manifold in {mathbb{R}^3} satisfying our prescribed initial conditions. To achieve this, we introduce a vanishing viscosity method depending on the features of initial value problems for isometric immersions and present a technique to make the a priori estimates including the L ? control and H -1-compactness for the viscous approximate solutions. This yields the weak convergence of the vanishing viscosity approximate solutions and the weak continuity of the Gauss-Codazzi system for the approximate solutions, hence the existence of an isometric immersion of the manifold into {mathbb{R}^3} satisfying our initial conditions. The theory is applied to a specific example of the metric associated with the catenoid.

  5. Permeability of compacting porous lavas

    NASA Astrophysics Data System (ADS)

    Ashwell, P. A.; Kendrick, J. E.; Lavallée, Y.; Kennedy, B. M.; Hess, K.-U.; Aulock, F. W.; Wadsworth, F. B.; Vasseur, J.; Dingwell, D. B.

    2015-03-01

    The highly transient nature of outgassing commonly observed at volcanoes is in part controlled by the permeability of lava domes and shallow conduits. Lava domes generally consist of a porous outer carapace surrounding a denser lava core with internal shear zones of variable porosity. Here we examine densification using uniaxial compression experiments on variably crystalline and porous rhyolitic dome lavas from the Taupo Volcanic Zone. Experiments were conducted at 900°C and an applied stress of 3 MPa to 60% strain, while monitoring acoustic emissions to track cracking. The evolution of the porous network was assessed via X-ray computed tomography, He-pycnometry, and relative gas permeability. High starting connected porosities led to low apparent viscosities and high strain rates, initially accompanied by abundant acoustic emissions. As compaction ensued, the lavas evolved; apparent viscosity increased and strain rate decreased due to strain hardening of the suspensions. Permeability fluctuations resulted from the interplay between viscous flow and brittle failure. Where phenocrysts were abundant, cracks had limited spatial extent, and pore closure decreased axial and radial permeability proportionally, maintaining the initial anisotropy. In crystal-poor lavas, axial cracks had a more profound effect, and permeability anisotropy switched to favor axial flow. Irrespective of porosity, both crystalline samples compacted to a threshold minimum porosity of 17-19%, whereas the crystal-poor sample did not achieve its compaction limit. This indicates that unconfined loading of porous dome lavas does not necessarily form an impermeable plug and may be hindered, in part by the presence of crystals.

  6. Anisotropic charged stellar models in Generalized Tolman IV spacetime

    NASA Astrophysics Data System (ADS)

    Murad, Mohammad Hassan; Fatema, Saba

    2015-01-01

    With the presence of electric charge and pressure anisotropy some anisotropic stellar models have been developed. An algorithm recently presented by Herrera et al. (Phys. Rev. D 77, 027502 (2008)) to generate static spherically symmetric anisotropic solutions of Einstein's equations has been used to derive relativistic anisotropic charged fluid spheres. In the absence of pressure anisotropy the fluid spheres reduce to some well-known Generalized Tolman IV exact metrics. The astrophysical significance of the resulting equations of state (EOS) for a particular case (Wyman-Leibovitz-Adler) for the anisotropic charged matter distribution has been discussed. Physical analysis shows that the relativistic stellar structure obtained in this work may reasonably model an electrically charged compact star, whose energy density associated with the electric fields is on the same order of magnitude as the energy density of fluid matter itself like electrically charged bare strange quark stars.

  7. Comparison of Obturation Quality in Modified Continuous Wave Compaction, Continuous Wave Compaction, Lateral Compaction and Warm Vertical Compaction Techniques

    PubMed Central

    Aminsobhani, Mohsen; Ghorbanzadeh, Abdollah; Sharifian, Mohammad Reza; Namjou, Sara; Kharazifard, Mohamad Javad

    2015-01-01

    Objectives: The aim of this study was to introduce modified continuous wave compaction (MCWC) technique and compare its obturation quality with that of lateral compaction (LC), warm vertical compaction (WVC) and continuous wave compaction techniques (CWC). The obturation time was also compared among the four techniques. Materials and Methods: Sixty-four single-rooted teeth with 0–5° root canal curve and 64 artificially created root canals with 15° curves in acrylic blocks were evaluated. The teeth and acrylic specimens were each divided into four subgroups of 16 for testing the obturation quality of four techniques namely LC, WVC, CWC and MCWC. Canals were prepared using the Mtwo rotary system and filled with respect to their group allocation. Obturation time was recorded. On digital radiographs, the ratio of area of voids to the total area of filled canals was calculated using the Image J software. Adaptation of the filling materials to the canal walls was assessed at three cross-sections under a stereomicroscope (X30). Data were statistically analyzed using ANOVA, Tukey’s post hoc HSD test, the Kruskal Wallis test and t-test. Results: No significant difference existed in adaptation of filling materials to canal walls among the four subgroups in teeth samples (P ? 0.139); but, in artificially created canals in acrylic blocks, the frequency of areas not adapted to the canal walls was significantly higher in LC technique compared to MCWC (P ? 0.02). The void areas were significantly more in the LC technique than in other techniques in teeth (P < 0.001). The longest obturation time belonged to WVC technique followed by LC, CW and MCWC techniques (P<0.05). The difference between the artificially created canals in blocks and teeth regarding the obturation time was not significant (P = 0.41). Conclusion: Within the limitations of this in vitro study, MCWC technique resulted in better adaptation of gutta-percha to canal walls than LC at all cross-sections with fewer voids and faster obturation time compared to other techniques.

  8. Compact CWDM design and packaging

    Microsoft Academic Search

    Christine Luo; Daoyi Wang; John Kong; Lingzhi Li; Jing Li; Andrew Chang; Yao Li; Wei-shin Tsay

    2004-01-01

    In order to reduce size and cost, and at the same time increase overall performance, we designed a compact 8-ch CWDM MUX\\/DeMUX scheme based on free space optics. The device offers the following competitive performance specifications: IL < 0.8dB, IL ripple < 0.2dB, PDL < 0.1dB, PMD < 0.15ps, CD < 3ps\\/nm, IL uniformity 40dB, return loss > 50dB and

  9. Compact Radiometers Expand Climate Knowledge

    NASA Technical Reports Server (NTRS)

    2010-01-01

    To gain a better understanding of Earth's water, energy, and carbon cycles, NASA plans to embark on the Soil Moisture Active and Passive mission in 2015. To prepare, Goddard Space Flight Center provided Small Business Innovation Research (SBIR) funding to ProSensing Inc., of Amherst, Massachusetts, to develop a compact ultrastable radiometer for sea surface salinity and soil moisture mapping. ProSensing incorporated small, low-cost, high-performance elements into just a few circuit boards and now offers two lightweight radiometers commercially. Government research agencies, university research groups, and large corporations around the world are using the devices for mapping soil moisture, ocean salinity, and wind speed.

  10. Dense and Homogeneous Compaction of Fine Ceramic and Metallic Powders: High-Speed Centrifugal Compaction Process

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroyuki Y.

    2008-02-01

    High-Speed Centrifugal Compaction Process (HCP) is a variation of colloidal compacting method, in which the powders sediment under huge centrifugal force. Compacting mechanism of HCP differs from conventional colloidal process such as slip casting. The unique compacting mechanism of HCP leads to a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, flawless microstructure of the green compacts, etc. However, HCP also has several deteriorative characteristics that must be overcome to fully realize this process' full potential.

  11. Brittle and compaction creep in porous sandstone

    NASA Astrophysics Data System (ADS)

    Heap, Michael; Brantut, Nicolas; Baud, Patrick; Meredith, Philip

    2015-04-01

    Strain localisation in the Earth's crust occurs at all scales, from the fracture of grains at the microscale to crustal-scale faulting. Over the last fifty years, laboratory rock deformation studies have exposed the variety of deformation mechanisms and failure modes of rock. Broadly speaking, rock failure can be described as either dilatant (brittle) or compactive. While dilatant failure in porous sandstones is manifest as shear fracturing, their failure in the compactant regime can be characterised by either distributed cataclastic flow or the formation of localised compaction bands. To better understand the time-dependency of strain localisation (shear fracturing and compaction band growth), we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (porosity = 24%) under a constant stress (creep) in the dilatant and compactive regimes, with particular focus on time-dependent compaction band formation in the compactive regime. Our experiments show that inelastic strain accumulates at a constant stress in the brittle and compactive regimes leading to the development of shear fractures and compaction bands, respectively. While creep in the dilatant regime is characterised by an increase in porosity and, ultimately, an acceleration in axial strain to shear failure (as observed in previous studies), compaction creep is characterised by a reduction in porosity and a gradual deceleration in axial strain. The overall deceleration in axial strain, AE activity, and porosity change during creep compaction is punctuated by excursions interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence background creep strain rate, is decreased, although the inelastic strain required for a compaction band remains constant over strain rates spanning several orders of magnitude. We find that, despite the large differences in strain rate and growth rate (from both creep and constant strain rate experiments), the characteristics (geometry, thickness) of a compaction band remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactive regimes, suggest that, as for dilatant creep, compactant creep is driven by subcritical stress corrosion cracking. We highlight the attendant implications for time-dependent porosity loss, subsidence, and permeability reduction in sandstone reservoirs.

  12. Compacted carbon for electrochemical cells

    DOEpatents

    Greinke, Ronald Alfred (Medina, OH); Lewis, Irwin Charles (Strongsville, OH)

    1997-01-01

    This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (i) an x-ray density of at least 2.00 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 47%; and (b) graphite having the following properties: (i) an x-ray density of at least 2.20 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counterelectrode.

  13. A compact THz imaging system

    NASA Astrophysics Data System (ADS)

    Sešek, Aleksander; Å vigelj, Andrej; Trontelj, Janez

    2015-03-01

    The objective of this paper is the development of a compact low cost imaging THz system, usable for observation of the objects near to the system and also for stand-off detection. The performance of the system remains at the high standard of more expensive and bulkiest system on the market. It is easy to operate as it is not dependent on any fine mechanical adjustments. As it is compact and it consumes low power, also a portable system was developed for stand-off detection of concealed objects under textile or inside packages. These requirements rule out all optical systems like Time Domain Spectroscopy systems which need fine optical component positioning and requires a large amount of time to perform a scan and the image capture pixel-by-pixel. They are also almost not suitable for stand-off detection due to low output power. In the paper the antenna - bolometer sensor microstructure is presented and the THz system described. Analysis and design guidelines for the bolometer itself are discussed. The measurement results for both near and stand-off THz imaging are also presented.

  14. Hydrostatic compaction of Microtherm HT.

    SciTech Connect

    Broome, Scott Thomas; Bauer, Stephen J.

    2010-09-01

    Two samples of jacketed Microtherm{reg_sign}HT were hydrostatically pressurized to maximum pressures of 29,000 psi to evaluate both pressure-volume response and change in bulk modulus as a function of density. During testing, each of the two samples exhibited large irreversible compactive volumetric strains with only small increases in pressure; however at volumetric strains of approximately 50%, the Microtherm{reg_sign}HT stiffened noticeably at ever increasing rates. At the maximum pressure of 29,000 psi, the volumetric strains for both samples were approximately 70%. Bulk modulus, as determined from hydrostatic unload/reload loops, increased by more than two-orders of magnitude (from about 4500 psi to over 500,000 psi) from an initial material density of {approx}0.3 g/cc to a final density of {approx}1.1 g/cc. An empirical fit to the density vs. bulk modulus data is K = 492769{rho}{sup 4.6548}, where K is the bulk modulus in psi, and {rho} is the material density in g/cm{sup 3}. The porosity decreased from 88% to {approx}20% indicating that much higher pressures would be required to compact the material fully.

  15. Compact hybrid Si microring lasers

    NASA Astrophysics Data System (ADS)

    Liang, Di; Bowers, John E.; Fiorentino, Marco; Beausoleil, Raymond G.

    2010-02-01

    In this paper we review the recent progress in developing compact microring lasers on the hybrid silicon platform. A simplified self-aligned process is used to fabricate devices as small as 15 ?m in diameter. The optically-pumped, continuous wave (cw) devices show low threshold carrier density, comparable to the carrier density to reach material transparency. In the electrically-pumped lasers, the short cavity length leads to the minimum laser threshold less than 5 mA in cw operation. The maximum cw lasing temperature is up to 65 °C. Detailed studies in threshold as a function of coupling coefficient and bus waveguide width are presented. Surface recombination at the dry-etched exposed interface is investigated qualitatively by studying the current-voltage characteristics. Ring resonator-based figures of merits including good spectral purity and large side-mode suppression ratio are demonstrated. Thermal impedance data is extracted from temperature-dependent spectral measurement, and buried oxide layer in silicon-on-insulator wafer is identified as the major thermal barrier to cause high thermal impedance for small-size devices. The demonstrated compact hybrid ring lasers have low power consumption, small footprint and dynamic performance. They are promising for Si-based optical interconnects and flip-flop applications.

  16. Compact Microscope Imaging System Developed

    NASA Technical Reports Server (NTRS)

    McDowell, Mark

    2001-01-01

    The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. The CMIS can be used in situ with a minimum amount of user intervention. This system, which was developed at the NASA Glenn Research Center, can scan, find areas of interest, focus, and acquire images automatically. Large numbers of multiple cell experiments require microscopy for in situ observations; this is only feasible with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control capabilities. The software also has a user-friendly interface that can be used independently of the hardware for post-experiment analysis. CMIS has potential commercial uses in the automated online inspection of precision parts, medical imaging, security industry (examination of currency in automated teller machines and fingerprint identification in secure entry locks), environmental industry (automated examination of soil/water samples), biomedical field (automated blood/cell analysis), and microscopy community. CMIS will improve research in several ways: It will expand the capabilities of MSD experiments utilizing microscope technology. It may be used in lunar and Martian experiments (Rover Robot). Because of its reduced size, it will enable experiments that were not feasible previously. It may be incorporated into existing shuttle orbiter and space station experiments, including glove-box-sized experiments as well as ground-based experiments.

  17. Manufacturability of compact synchrotron mirrors

    NASA Astrophysics Data System (ADS)

    Douglas, Gary M.

    1997-11-01

    While many of the government funded research communities over the years have put their faith and money into increasingly larger synchrotrons, such as Spring8 in Japan, and the APS in the United States, a viable market appears to exist for smaller scale, research and commercial grade, compact synchrotrons. These smaller, and less expensive machines, provide the research and industrial communities with synchrotron radiation beamline access at a portion of the cost of their larger and more powerful counterparts. A compact synchrotron, such as the Aurora-2D, designed and built by Sumitomo Heavy Industries, Ltd. of japan (SHI), is a small footprint synchrotron capable of sustaining 20 beamlines. Coupled with a Microtron injector, with 150 MeV of injection energy, an entire facility fits within a 27 meter [88.5 ft] square floorplan. The system, controlled by 2 personal computers, is capable of producing 700 MeV electron energy and 300 mA stored current. Recently, an Aurora-2D synchrotron was purchased from SHI by the University of Hiroshima. The Rocketdyne Albuquerque Operations Beamline Optics Group was approached by SHI with a request to supply a group of 16 beamline mirrors for this machine. These mirrors were sufficient to supply 3 beamlines for the Hiroshima machine. This paper will address engineering issues which arose during the design and manufacturing of these mirrors.

  18. Compactness Handout #6 --3/11/96

    E-print Network

    Sharpley, Robert

    is continuous and K is compact. Each open cover C of f [K] can be drawn back to an open cover ~ C of K, by considering the sets ~ O := f \\Gamma1 (O); O 2 C: K compact implies that we may draw a finite subcover from K is compact. Proof. Let ~ G be an open cover for C. Let O 0 be the complement of C, then O 0

  19. Method for preparing porous metal hydride compacts

    DOEpatents

    Ron, M.; Gruen, D.M.; Mendelsohn, M.H.; Sheft, I.

    1980-01-21

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  20. Method for preparing porous metal hydride compacts

    DOEpatents

    Ron, Moshe (Haifa, IL); Gruen, Dieter M. (Downers Grove, IL); Mendelsohn, Marshall H. (Woodridge, IL); Sheft, Irving (Oak Park, IL)

    1981-01-01

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  1. Charge regulation circuit

    DOEpatents

    Ball, Don G. (Livermore, CA)

    1992-01-01

    A charge regulation circuit provides regulation of an unregulated voltage supply in the range of 0.01%. The charge regulation circuit is utilized in a preferred embodiment in providing regulated voltage for controlling the operation of a laser.

  2. Pasta structures in compact stars

    E-print Network

    Toshiki Maruyama; Toshitaka Tatsumi; Tomoki Endo; Satoshi Chiba

    2006-05-31

    We review our recent works about ``pasta'' structures following the first-order phase transition in dense matter, which correspond to the structured mixed phases with geometrical symmetries. Three kinds of phase transitions at different density ranges are examined as the stages of pasta structures: liquid-gas phase transition at subnuclear density, kaon condensation and hadron-quark phase transition at high density. Charge density as well as particle density is non-uniform there. A consistent treatment of the Coulomb potential and the particle densities is presented and a peculiar role of the Coulomb potential is elucidated: the physical picture of the Maxwell construction will be effectively recovered. It largely influences the density regime of pasta structures by the charge screening effect.

  3. Modelling airport congestion charges

    Microsoft Academic Search

    Milan Janic

    2005-01-01

    This article deals with modelling congestion charges at an airport. In this context, congestion charging represents internalizing the cost of marginal delays that a flight imposes on other flights due to congestion. The modelling includes estimating congestion and flight delays, the cost of these delays and the efficiency of particular flights following the introduction of a congestion charge. The models

  4. Particle charge spectrometer

    NASA Technical Reports Server (NTRS)

    Fuerstenau, Stephen D. (Inventor)

    2004-01-01

    An airflow through a tube is used to guide a charged particle through the tube. A detector may be used to detect charge passing through the tube on the particle. The movement of the particle through the tube may be used to both detect its charge and size.

  5. Compact Quantum Cascade Laser Transmitter

    SciTech Connect

    Anheier, Norman C.; Hatchell, Brian K.; Gervais, Kevin L.; Wojcik, Michael D.; Krishnaswami, Kannan; Bernacki, Bruce E.

    2009-04-01

    ): In this paper we present design considerations, thermal and optical modeling results, and device performance for a ruggedized, compact laser transmitter that utilizes a room temperature quantum cascade (QC) laser source. The QC laser transmitter is intended for portable mid-infrared (3-12 µm) spectroscopy applications, where the atmospheric transmission window is relatively free of water vapor interference and where the molecular rotational vibration absorption features can be used to detect and uniquely identify chemical compounds of interest. Initial QC laser-based sensor development efforts were constrained by the complications of cryogenic operation. However, improvements in both QC laser designs and fabrication processes have provided room-temperature devices that now enable significant miniaturization and integration potential for national security, environmental monitoring, atmospheric science, and industrial safety applications.

  6. Compact Sources of Ultrashort Pulses

    NASA Astrophysics Data System (ADS)

    Duling, Irl N., III

    1995-10-01

    List of contributors; Acronyms and abbreviations; Preface; 1. Short pulse generation H. A. Haus; 2. Passive modelocking in solid state lasers Thomas Brabec, Stephen M. J. Kelly and Ferenc Krausz; 3. Compact modelocked solid state lasers pumped by laser diodes John R. M. Barr; 4. Modelocking of all-fiber lasers Irl N. Duling, III and Michael L. Dennis; 5. Nonlinear polarization evolution in passively modelocked fiber lasers Martin E. Fermann; 6. Ultrafast vertical cavity semiconductor lasers Wenbin Jiang and John Bowers; 7. High power ultrafast semiconductor for injection diode lasers Peter J. Delfyett; 8. The hybrid soliton pulse source Paul A. Morton; 9. Monolithic colliding pulse modelocked diode lasers Ming C. Wu and Young-Kai Chen; Index.

  7. Compact Sources of Ultrashort Pulses

    NASA Astrophysics Data System (ADS)

    Duling, Irl N., III

    2006-11-01

    List of contributors; Acronyms and abbreviations; Preface; 1. Short pulse generation H. A. Haus; 2. Passive modelocking in solid state lasers Thomas Brabec, Stephen M. J. Kelly and Ferenc Krausz; 3. Compact modelocked solid state lasers pumped by laser diodes John R. M. Barr; 4. Modelocking of all-fiber lasers Irl N. Duling, III and Michael L. Dennis; 5. Nonlinear polarization evolution in passively modelocked fiber lasers Martin E. Fermann; 6. Ultrafast vertical cavity semiconductor lasers Wenbin Jiang and John Bowers; 7. High power ultrafast semiconductor for injection diode lasers Peter J. Delfyett; 8. The hybrid soliton pulse source Paul A. Morton; 9. Monolithic colliding pulse modelocked diode lasers Ming C. Wu and Young-Kai Chen; Index.

  8. Studies of accelerated compact toruses

    SciTech Connect

    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.

  9. Experimental studies of compact toroids

    SciTech Connect

    Not Available

    1991-01-01

    The Berkeley Compact Toroid Experiment (BCTX) device is a plasma device with a Marshall-gun generated, low aspect ratio toroidal plasma. The device is capable of producing spheromak-type discharges and may, with some modification, produce low-aspect ratio tokamak configurations. A unique aspect of this experimenal devie is its large lower hybrid (LH) heating system, which consists of two 450MHz klystron tubes generating 20 megawatts each into a brambilla-type launching structure. Successful operation with one klystron at virtually full power (18 MW) has been accomplished with 110 {mu}s pulse length. A second klystron is currently installed in its socket and magnet but has not been added to the RF drive system. This report describes current activities and accomplishments and describes the anticipated results of next year's activity.

  10. A hypercube compact neural network

    SciTech Connect

    Rostykus, P.L.; Somani, A.K.

    1988-09-01

    A major problem facing implementation of neural networks is the connection problem. One popular tradeoff is to remove connections. Random disconnection severely degrades the capabilities. The hypercube based Compact Neural Network (CNN) has structured architecture combined with a rearrangement of the memory vectors gives a larger input space and better degradation than a cost equivalent network with more connections. The CNNs are based on a Hopfield network. The changes from the Hopfield net include states of -1 and +1 and when a node was evaluated to 0, it was not biased either positive or negative, instead it resumed its previous state. L = PEs, N = memories and t/sub ij/s is the weights between i and j.

  11. General Relativity&Compact Stars

    SciTech Connect

    Glendenning, Norman K.

    2005-08-16

    Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.

  12. Physics of Compact Advanced Stellarators

    SciTech Connect

    M.C. Zarnstorff; L.A. Berry; A. Brooks; E. Fredrickson; G.-Y. Fu; S. Hirshman; S. Hudson; L.-P. Ku; E. Lazarus; D. Mikkelsen; D. Monticello; G.H. Neilson; N. Pomphrey; A. Reiman; D. Spong; D. Strickler; A. Boozer; W.A. Cooper; R. Goldston; R. Hatcher; M. Isaev; C. Kessel; J. Lewandowski; J. Lyon; P. Merkel; H. Mynick; B.E. Nelson; C. Nuehrenberg; M. Redi; W. Reiersen; P. Rutherford; R. Sanchez; J. Schmidt; R.B. White

    2001-08-14

    Compact optimized stellarators offer novel solutions for confining high-beta plasmas and developing magnetic confinement fusion. The 3-D plasma shape can be designed to enhance the MHD stability without feedback or nearby conducting structures and provide drift-orbit confinement similar to tokamaks. These configurations offer the possibility of combining the steady-state low-recirculating power, external control, and disruption resilience of previous stellarators with the low-aspect ratio, high beta-limit, and good confinement of advanced tokamaks. Quasi-axisymmetric equilibria have been developed for the proposed National Compact Stellarator Experiment (NCSX) with average aspect ratio 4-4.4 and average elongation of approximately 1.8. Even with bootstrap-current consistent profiles, they are passively stable to the ballooning, kink, vertical, Mercier, and neoclassical-tearing modes for beta > 4%, without the need for external feedback or conducting walls. The bootstrap current generates only 1/4 of the magnetic rotational transform at beta = 4% (the rest is from the coils), thus the equilibrium is much less nonlinear and is more controllable than similar advanced tokamaks. The enhanced stability is a result of ''reversed'' global shear, the spatial distribution of local shear, and the large fraction of externally generated transform. Transport simulations show adequate fast-ion confinement and thermal neoclassical transport similar to equivalent tokamaks. Modular coils have been designed which reproduce the physics properties, provide good flux surfaces, and allow flexible variation of the plasma shape to control the predicted MHD stability and transport properties.

  13. A compact high power pulsed modulator based on spiral Blumlein line.

    PubMed

    Liu, Jinliang; Yin, Yi; Ge, Bin; Cheng, Xinbing; Feng, Jiahuai; Zhang, Jiande; Wang, Xinxin

    2007-10-01

    A compact high power pulsed modulator based on spiral water Blumlein line, which consists of primary storage capacitors, a Tesla transformer, a spiral Blumlein line of water dielectric, and a field-emission diode, is described. The experimental results showed that the diode voltage is more than 500 kV, the electron beam current of diode is about 32 kA, and the pulse duration is about 180 ns. The distributions for electrical field in the spiral water Blumlein line were obtained by the simulations. In addition, the process of the charging a spiral Blumlein line was simulated through the PSPICE software to get the wave form of charging voltage of pulse forming line, the diode voltage, and diode current of modulator. The theoretical and simulated results are in agreement. This accelerator is very compact and works stably and reliably. PMID:17979411

  14. Hydraulic conductivity tests on compacted clay

    Microsoft Academic Search

    Stephen S. Boynton; David E. Daniel

    1985-01-01

    Permeability tests were performed in the laboratory on compacted clay to study the effects of type of permeameter, hydraulic anisotropy, diameter of test specimens, storage time, and desiccation cracking. Essentially identical hydraulic conductivities were measured with compaction-mold, consolidationcell, and flexible-wall permeameters. With good bonding between lifts, hydraulic conductivity was isotropic. Test specimens having a diameter of 15 cm were twice

  15. Homogeneous test specimens from gyratory compaction

    Microsoft Academic Search

    P. M. Muraya

    2007-01-01

    This paper presents a study on the production of homogeneous test specimens using gyratory compaction that was performed as part of a research that is currently being conducted at the Delft University of Technology on permanent deformation of asphalt mixtures. The main aim of this study was to establish suitable gyratory compactor protocols for preparation of homogeneous test specimens compacted

  16. Low-cost compact CWDM filter platform

    Microsoft Academic Search

    Yao Li; Christine Luo; Daoyi Wang; Lingzhi Li; Jing Li; Frank Wu; Wei-shin Tsay

    2004-01-01

    We discuss recent surge of interests in coarse DWM (CWDM) applications and implied challenges for low cost and compact devices. We show that for further cost-reduction and performance enhancements, an old WDM packaging architecture can be revitalized to address the new compact CWDM (CCWDM) filter challenges. In particular, we demonstrate a CCWDM filter platform and show its use in both

  17. Compaction Within the South Belridge Diatomite

    Microsoft Academic Search

    Chase C. A. Jr; J. K. Dietrich

    1989-01-01

    Compaction is incorporated into a field-scale finite-difference thermal simulator to allow practical engineering analysis of reservoir compaction caused by fluid withdrawal. Capabilities new to petroleum applications include hysteresis in the form of limited rebound during fluid injection and the concept of relaxation time (i.e., creep).

  18. Compaction within the South Belridge diatomite

    SciTech Connect

    Chase C.A. Jr.; Dietrich, J.K. (Todd, Dietrich and Chase Inc., Durango, CO (US))

    1989-11-01

    Compaction is incorporated into a field-scale finite-difference thermal simulator to allow practical engineering analysis of reservoir compaction caused by fluid withdrawal. Capabilities new to petroleum applications include hysteresis in the form of limited rebound during fluid injection and the concept of relaxation time (i.e., creep).

  19. Probing the Environment of Accreting Compact Objects

    Microsoft Academic Search

    Manfred Hanke

    2011-01-01

    X-ray binaries are the topic of this thesis. They consist of a compact object -- a black hole or a neutron star -- and an ordinary star, which loses matter to the compact object. The gravitational energy released through this process of mass accretion is largely converted into X-rays. The latter are used in the present work to screen the

  20. Compact poly-CMP embedded flash memory

    Microsoft Academic Search

    Rob van Schaijk; Nicole Wils; Michiel Slotboom; Frans Widdershoven

    2001-01-01

    In this paper, the compact poly-CMP cell concept is presented as a good candidate for scaled embedded flash memory in future mainstream CMOS technologies. In this compact cell concept the access gate is placed next to the stacked gate transistor. The access gate has a flat top surface due to the use of chemical mechanical polishing (CMP) and therefore no

  1. 3D N = 4 Gauge Theory Compactication

    E-print Network

    Bigelow, Stephen

    Outline 3D N = 4 Gauge Theory Compactication Twistors 3D N = 4 Supersymmetric Gauge Theories and Hyperk¨ahler Metrics Richard Eager UCSB Friday, October 17th, 2008, 4:00 p.m. Richard Eager UCSB 3D N = 4 Supersymmetric Gauge Theories and Hyperk¨ahler M #12;Outline 3D N = 4 Gauge Theory Compactication Twistors

  2. Roller compacted concrete with contaminated recycled aggregates

    Microsoft Academic Search

    Farid Debieb; Luc Courard; Said Kenai; Robert Degeimbre

    2009-01-01

    Recycling waste building materials from construction and demolition (C&D) sites is increasingly investigated for economical and environmental reasons. Roller compacted concrete (RCC) is a special dry concrete mix; laid down and compacted like a soil, it is especially used for the construction of massive structures like dams or large horizontal surfaces like road foundation. In this paper, natural concrete slabs

  3. Compact Process Development at Babcock & Wilcox

    SciTech Connect

    Eric Shaber; Jeffrey Phillips

    2012-03-01

    Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of compaction trials have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel at packing fractions exceeding 46% by volume. Results from these trials are included. The scale-up effort is nearing completion with the process installed and operable using nuclear fuel materials. Final process testing is in progress to certify the process for manufacture of qualification test fuel compacts in 2012.

  4. MAST-Upgrade Advancing compact fusion sources

    E-print Network

    MAST-Upgrade Advancing compact fusion sources #12;#12;The Mega Amp Spherical Tokamak (MAST) is the centrepiece of the UK's fusion research programme. It has led studies into the spherical tokamak, a compact to the drive towards commercial fusion power. 1. Testing reactor concepts. MAST-Upgrade will be the first

  5. Hierarchical pitchmatching compaction using minimum design

    Microsoft Academic Search

    Cyrus S. Bamji; Ravi Varadarajan

    1992-01-01

    A new hiemrchical compactor capable of compacting and $he hierarchical com~actor can handle most input hieraritchmatching hierarchically dejined layouts is described. chies including multt-leuel hierarchies, over the cell routing and cell rotations and rejections. The compactor simultaneously compacts the contents of all the cells of the layout hierarchy maintaining the hierarchy of the input layout as well as the f

  6. Compact Plan Summary-CVM Veterinary Medicine

    E-print Network

    Langerhans, Brian

    9/13/00 Compact Plan Summary-CVM 1 Veterinary Medicine Compact Plan Summary September 14, 2000 Animal Cancer Treatment Program (NCACTP) · Veterinary Medical Center *Diversity (funds will become the Educational Benefits of the Teaching Animal Unit (TAU) Veterinary Clinical Trials Program Veterinary Scholars

  7. Weakly compact generating and shrinking Markusevic bases

    E-print Network

    Montesinos Santalucía, Vicente

    Weakly compact generating and shrinking Markusevic bases M. Fabian , P. H´ajek , V. Montesinos A1019205 (Czech Republic). Key Words: Weakly compactly generated spaces, shrinking Markusevic bases; x } which is shrinking, that is, sp{x ; } is norm dense in X . Note that not every Markusevic

  8. Compaction with shape optimization [IC layout

    Microsoft Academic Search

    Kazuhisa Okada; Hidetoshi Onodera; Keikichi Tamaru

    1994-01-01

    We propose a new compaction problem that allows layout elements to have many shape possibilities. The objective of the problem is to find not only positions but also shapes of layout elements. We present an efficient method to solve the problem-compaction with shape optimization. This method simplifies the problem by considering the optimization of shapes only for the layout elements

  9. Evolution of highly compact binary stellar systems

    SciTech Connect

    Rappaport, S.; Joss, P.C.; Webbink, R.F.

    1982-03-15

    We have calculated the evolution of close binary stellar systems composed of a collapsed star and a low-mass companion in an orbit with a period of approx.3 hours or less at the onset of mass transfer. The low-mass (secondary) star is assumed to transfer mass onto the collapsed (primary) star due to the decay of the orbit resulting from gravitational radiation. Under these circumstances, the secondary is well represented by an n = 3/2 polytrope. By utilizing this approximation, we are able to explore the effects of varying a number of physical parameters, including the stellar masses, the composition of the secondary, and mass and angular momentum losses from the system. Moreover, we are able to follow the evolution until the secondary has been almost completely consumed. For a wide range of parameters, even with extreme angular momentum losses (as long as those losses are proportional to the mass transfer rate), the transfer rate for a large portion of the evolution is tightly constrained to < or =2 x 10/sup -10/ M/sub sun/ yr/sup -1/, in good agreement with the rates inferred from many cataclysmic variables.

  10. Compact Dielectric Wall Accelerator Development For Intensity Modulated Proton Therapy And Homeland Security Applications

    SciTech Connect

    Chen, Y -; Caporaso, G J; Guethlein, G; Sampayan, S; Akana, G; Anaya, R; Blackfield, D; Cook, E; Falabella, S; Gower, E; Harris, J; Hawkins, S; Hickman, B; Holmes, C; Horner, A; Nelson, S; Paul, A; Pearson, D; Poole, B; Richardson, R; Sanders, D; Stanley, J; Sullivan, J; Wang, L; Watson, J; Weir, J

    2009-06-17

    Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory. The DWA accelerator uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. Its high electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The DWA concept can be applied to accelerate charge particle beams with any charge to mass ratio and energy. Based on the DWA system, a novel compact proton therapy accelerator is being developed. This proton therapy system will produce individual pulses that can be varied in intensity, energy and spot width. The system will be capable of being sited in a conventional linac vault and provide intensity modulated rotational therapy. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, SiC photoconductive switches and compact proton sources. Applications of the DWA accelerator to problems in homeland security will also be discussed.

  11. Vibration-induced compaction of granular suspensions.

    PubMed

    Kiesgen de Richter, S; Hanotin, C; Marchal, P; Leclerc, S; Demeurie, F; Louvet, N

    2015-07-01

    We investigate the compaction dynamics of vibrated granular suspensions using both digital imaging technique and MRI measurements. Starting from initialy loose packings, our experimental data suggest the existence of two stages in the compaction dynamics: a fast stage at short times where a rising compaction front propagates through the granular suspension and a slow stage at large times where the packing compacts slowly and homogeneously. The compaction dynamics in each stage can be well fitted to usual stretched exponential laws with stretching exponents equal to 2 and 0.45, respectively. The transition time between these two stages, ? c , depends on the fluid viscosity, vibration intensity and grain diameter. We show that ? c (-1) and the velocity of the front decrease roughly linearly with the lubrication Peclet number, Pe lub related to the competition between the lubrication stress induced by vibrations and the granular pressure. PMID:26164824

  12. Accurate, Compact, and Power-Efficient Li-Ion Battery Charger Circuit

    Microsoft Academic Search

    Min Chen; Gabriel A. Rincon-Mora

    2006-01-01

    A novel, accurate, compact, and power-efficient lithium-ion (Li-Ion) battery charger designed to yield maximum capacity, cycle life, and therefore runtime is presented and experimentally verified. The proposed charger uses a diode to smoothly (i.e., continuously) transition between two high-gain linear feedback loops and control a single power MOS device, automatically charging the battery with constant current and then constant voltage.

  13. The RADAN series of compact pulsed power Generators and their applications

    Microsoft Academic Search

    GENNADY A. MESYATS; SERGEI D. KOROVIN; VLADISLAV V. ROSTOV; VALERY G. SHPAK; MICHAEL I. YALANDIN

    2004-01-01

    This paper presents results of development of a compact pulsed power high-voltage generators and high-current electron accelerators of the RADAN series. The basic high-voltage units of RADAN instruments are built around coaxial pulsed forming lines and efficient charging device represented by a Tesla transformer. The fields of applications in science and in practice are rather wide and include formation of

  14. Development Of A Compact, High-energy Spark Gap Switch And Trigger Generator System

    Microsoft Academic Search

    D. Bhasavanich; S. S. Hitchcock; P. M. Creely; R. S. Shaw; H. G. Hammon; J. T. Naff

    1991-01-01

    High-energy switches and trigger generators are required for a range of capacitor banks in electric gun applications. We have developed a compact, long-lived spark gap and a matched series-injection trigger generator. The switch is of a two-electrode design using high density graphite electrodes. The demonstrated peak current capability is near 300 kA, with a charge transfer of 700 Cb, and

  15. Low-Power and Compact CMOS APS Circuits for Hybrid Cryogenic Infrared Fast Imaging

    Microsoft Academic Search

    Francisco Serra-Graells; Bertrand Misischi; Eduardo Casanueva; CÉsar Mendez; LluÍs Teres

    2007-01-01

    This brief presents a complete set of CMOS basic building blocks for low-cost scanning infrared (IR) cryogenic imagers. Low-power and compact novel circuits are proposed for single-capacitor integration and correlated double sampling, embedded pixel test, pixel charge-multiplexing and video composition and buffering. In order to validate the new basic building blocks, experimental results are reported in standard 0.35-mum CMOS technology

  16. Application of a compact microwave ion source to radiocarbon analysis

    SciTech Connect

    Schneider, R. J.; Reden, K. F. von; Hayes, J. M.; Wills, J. S. C. [NOSAMS Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 (United States); AECL Chalk River Laboratories, Chalk River, Ontario, K0J 1J0 (Canada)

    1999-04-26

    The compact, high current, 2.45 GHz microwave-driven plasma ion source which was built for the Chalk River TASCC facility is presently being adapted for testing as a gas ion source for accelerator mass spectrometry, at the Woods Hole Oceanographic Institution accelerator mass spectrometer. The special requirements for producing carbon-ion beams from micromole quantities of carbon dioxide produced from environmental samples will be discussed. These samples will be introduced into the ion source by means of argon carrier gas and a silicon capillary injection system. Following the extraction of positive ions from the source, negative ion formation in a charge exchange vapor will effectively remove the argon from the carbon beam. Simultaneous injection of the three carbon isotopes into the accelerator is planned.

  17. NHS prescription charges.

    PubMed

    2015-04-01

    In 2009, DTB published an editorial calling for the abolition of the NHS prescription charge.1 The article highlighted that from April 2011, England would be the only UK country that would tax patients for medicines through levying a prescription charge. In addition, it noted that the categorisation of medical and other exemptions is illogical and that the prescription charge is a poorly conceived, manifestly unfair tax. Of particular concern is the impact of the prescription charge on patients with chronic conditions that do not fall into the exemption categories. For many years the Prescription Charges Coalition, an alliance of more than 30 organisations concerned with the impact of prescription charges on people with long-term conditions, has campaigned to extend exemption from prescription charges to all those with long-term conditions.2 A subsequent DTB editorial, published in 2014, discussed anomalies associated with the prescription charge, including the cost of administering the bureaucracy needed to underpin the collection and checking of exemptions, and management of pre-payment certification.3 The editorial repeated the call for prescription charges to be abolished. Revisiting these themes, here we present an overview of the results of a survey conducted to explore the views of healthcare professionals on the NHS prescription charge. PMID:25858816

  18. Policy Implications from: -Charging Surveys

    E-print Network

    California at Davis, University of

    Q C #12;Statewide Quick Charging Choices #12;Workplace Charging #12;Free Charging #12;Congestion #12Policy Implications from: -Charging Surveys -Charging models IEEE November 7, 2013 Michael Nicholas Spatial & Temporal PEV Energy Use · GIS analysis · Charging network design · CEC, Nissan, ECOtality

  19. Compaction of North-sea chalk

    NASA Astrophysics Data System (ADS)

    Keszthelyi, Dániel; Dysthe, Dag Kristian; Jamtveit, Bjørn

    2014-05-01

    The Ekofisk field is the largest petroleum field in the Norwegian North Sea territory where oil is produced from chalk formations. Early stage of oil production caused considerable changes in pore fluid pressure which led to a reservoir compaction. Pore collapse mechanism caused by the dramatic increase of effective stress, which in turn was caused by the pressure reduction by hydrocarbon depletion, was early identified as a principal reason for the reservoir compaction (Sulak et al. 1991). There have been several attempts to model this compaction. They performed with variable success on predicting the Ekofisk subsidence. However, the most of these models are based on empirical relations and do not investigate in detail the phenomena involved in the compaction. In sake of predicting the Ekofisk subsidence while using only independently measurable variables we used a chalk compaction model valid on geological time-scales (Japsen et al. 2011) assuming plastic pore-collapse mechanism at a threshold effective stress level. We identified the phenomena involved in the pore collapse. By putting them in a sequential order we created a simple statistical analytical model. We also investigated the time-dependence of the phenomena involved and by assuming that one of the phenomena is rate-limiting we could make estimations of the compaction rate at smaller length-scales. By carefully investigating the nature of pressure propagation we could upscale our model to reservoir scale. We found that the predicted compaction rates are close enough to the measured rates. We believe that we could further increase accuracy by refining our model. Sulak, R. M., Thomas, L. K., Boade R. R. (1991) 3D reservoir simulation of Ekofisk compaction drive. Journal of Petroleum Technology, 43(10):1272-1278, 1991. Japsen, P., Dysthe, D. K., Hartz, E. H., Stipp, S. L. S., Yarushina, V. M., Jamtveit. (2011) A compaction front in North Sea chalk. Journal of Geophysical Research: Solid Earth (1978-2012), 116(B11)

  20. Compact stellarators with modular coils.

    PubMed

    Garabedian, P R

    2000-07-18

    Compact stellarator designs with modular coils and only two or three field periods are now available; these designs have both good stability and quasiaxial symmetry providing adequate transport for a magnetic fusion reactor. If the bootstrap current assumes theoretically predicted values a three field period configuration is optimal, but if that net current turns out to be lower, a device with two periods and just 12 modular coils might be better. There are also attractive designs with quasihelical symmetry and four or five periods whose properties depend less on the bootstrap current. Good performance requires that there be a satisfactory magnetic well in the vacuum field, which is a property lacking in a stellarator-tokamak hybrid that has been proposed for a proof of principle experiment. In this paper, we present an analysis of stability for these configurations that is based on a mountain pass theorem asserting that, if two solutions of the problem of magnetohydrodynamic equilibrium can be found, then there has to be an unstable solution. We compare results of our theory of equilibrium, stability, and transport with recently announced measurements from the large LHD experiment in Japan. PMID:10899993

  1. Compact stellarators with modular coils

    PubMed Central

    Garabedian, P. R.

    2000-01-01

    Compact stellarator designs with modular coils and only two or three field periods are now available; these designs have both good stability and quasiaxial symmetry providing adequate transport for a magnetic fusion reactor. If the bootstrap current assumes theoretically predicted values a three field period configuration is optimal, but if that net current turns out to be lower, a device with two periods and just 12 modular coils might be better. There are also attractive designs with quasihelical symmetry and four or five periods whose properties depend less on the bootstrap current. Good performance requires that there be a satisfactory magnetic well in the vacuum field, which is a property lacking in a stellarator-tokamak hybrid that has been proposed for a proof of principle experiment. In this paper, we present an analysis of stability for these configurations that is based on a mountain pass theorem asserting that, if two solutions of the problem of magnetohydrodynamic equilibrium can be found, then there has to be an unstable solution. We compare results of our theory of equilibrium, stability, and transport with recently announced measurements from the large LHD experiment in Japan. PMID:10899993

  2. Charging the Superconformal Index

    E-print Network

    Benjamin I. Zwiebel

    2012-03-14

    The superconformal index is an important invariant of superconformal field theories. In this note we refine the superconformal index by inserting the charge conjugation operator C. We construct a matrix integral for this charged index for N=4 SYM with SU(N) gauge group. The key ingredient for the construction is a "charged character," which reduces to Tr(C) for singlet representations of the gauge group. For each irreducible real SU(N) representation, we conjecture that this charged character is equal to the standard character for a corresponding representation of SO(N+1) or SP(N-1), for N even or odd respectively. The matrix integral for the charged index passes tests for small N and for N -> infinity. Like the ordinary superconformal index, for N=4 SYM the charged index is independent of N in the large-N limit.

  3. Shaped charge perforating device

    SciTech Connect

    Ayers, D.B.

    1986-04-22

    A shaped charge perforating apparatus is described which consists of: an elongated tubular housing member having recesses spirally spaced therealong; an elongated tubular carrier member having shaped charge mounting locations spirally spaced therealong; a plurality of shaped charge units positioned in the mounting locations of the carrier member; a length of detonator cord helically wound about the tubular carrier member for transferring detonation waves to the shaped charge units and for retaining the shaped charge units within the mounting locations; and means for aligning the tubular carrier within the tubular housing member so as to align the shaped charge units with the spaced recesses along the housing member, the alignment means further comprising an elongated slot in the housing member; and biasing means affixed to the carrier member for engagement within the slot.

  4. PICOBIT: A Compact Scheme System for Microcontrollers

    NASA Astrophysics Data System (ADS)

    St-Amour, Vincent; Feeley, Marc

    Due to their tight memory constraints, small microcontroller based embedded systems have traditionally been implemented using low-level languages. This paper shows that the Scheme programming language can also be used for such applications, with less than 7 kB of total memory. We present PICOBIT, a very compact implementation of Scheme suitable for memory constrained embedded systems. To achieve a compact system we have tackled the space issue in three ways: the design of a Scheme compiler generating compact bytecode, a small virtual machine, and an optimizing C compiler suited to the compilation of the virtual machine.

  5. Ultra-compact (X-ray) binaries

    E-print Network

    G. Nelemans; P. G. Jonker

    2006-05-30

    A short review of ultra-compact binaries, focused on ultra-compact X-ray binaries, is followed by a discussion of recent results of our VLT campaign to obtain optical spectra of (candidate) ultra-compact X-ray binaries. We find evidence for carbon/oxygen as well as helium/nitrogen discs and no evidence for (traces) of hydrogen. This suggests that the donors in the observed systems are white dwarfs. However, we also find large differences between the two C/O discs of which we have good spectra, which highlights the need for a better understanding of the optical spectra.

  6. Compact Monoidal Categories from Linguistics to Physics

    NASA Astrophysics Data System (ADS)

    Lambek, J.

    This is largely an expository paper, revisiting some ideas about compact 2-categories, in which each 1-cell has both a left and a right adjoint. In the special case with only one 0-cell (where the 1-cells are usually called "objects") we obtain a compact strictly monoidal category. Assuming furthermore that the 2-cells describe a partial order, we obtain a compact partially ordered monoid, which has been called a pregroup. Indeed, a pregroup in which the left and right adjoints coincide is just a partially ordered group (= pogroup).

  7. Compacting a Kentucky coal for quality logs

    SciTech Connect

    Lin, Y.; Li, Z.; Mao, S.

    1999-07-01

    A Kentucky coal was found more difficult to be compacted into large size strong logs. Study showed that compaction parameters affecting the strength of compacted coal logs could be categorized into three groups. The first group is coal inherent properties such as elasticity and coefficient of friction, the second group is machine properties such as mold geometry, and the third group is the coal mixture preparation parameters such as particle size distribution. Theoretical analysis showed that an appropriate backpressure can reduce surface cracks occurring during ejection. This has been confirmed by the experiments conducted.

  8. Battery formation charging apparatus

    SciTech Connect

    Stewart, J.L.

    1987-08-04

    An apparatus is describe for charging electric storage batteries, the apparatus comprising: (a) a host computer for providing charging information to and receiving status information from at least one slave computer by means of a data link; and (b) at least one control module coupled to the slave computer for applying charging current to at least one electric storage battery in response to instructions received from the slave computer, and for providing feedback and status information to the slave computer.

  9. Charging of interplanetary grains

    NASA Technical Reports Server (NTRS)

    Baragiola, R. A.; Johnson, R. E.; Newcomb, John L.

    1995-01-01

    The objective of this program is to quantify, by laboratory experiments, the charging of ices and other insulators subject to irradiation with electrons, ions and ultraviolet photons and to model special conditions based on the data. The system and conditions to be studied are those relevant for charging of dust in magnetospheric plasmas. The measurements are supplemented by computer simulations of charging or grains under a variety of conditions. Our work for this period involved experiments on water ice, improved models of charging of ice grains for Saturn's E-ring, and the construction of apparatus for electron impact studies and measurements of electron energy distributions.

  10. Strongly Charged Polymer Brushes

    E-print Network

    Ben O'Shaughnessy; Qingbo Yang

    2005-08-10

    Charged polymer brushes are layers of surface-tethered chains. Experimental systems are frequently strongly charged. Here we calculate phase diagrams for such brushes in terms of salt concentration n_s, grafting density and polymer backbone charge density. Electrostatic stiffening and counterion condensation effects arise which are absent from weakly charged brushes. In various phases chains are locally or globally fully stretched and brush height H has unique scaling forms; at higher salt concentrations we find H ~ n_s^(-1/3), in good agreement with experiment.

  11. A CMOS-compatible compact display

    E-print Network

    Chen, Andrew R. (Andrew Raymond)

    2005-01-01

    Portable information devices demand displays with high resolution and high image quality that are increasingly compact and energy-efficient. Microdisplays consisting of a silicon CMOS backplane integrated with light ...

  12. Microchemical Systems (MCS) for Compact Fuel Processing

    E-print Network

    Besser, Ronald S.

    Microchemical Systems (MCS) for Compact Fuel Processing Prof. R.S. Besser Chemical, Biomedical in MCS Understanding Steam Reforming of MeOH as a Model for Thermal Integration Issues in MCS As critical

  13. Gravitational waves from merging compact binaries

    E-print Network

    Hughes, Scott A.

    Largely motivated by the development of highly sensitive gravitational-wave detectors, our understanding of merging compact binaries and the gravitational waves they generate has improved dramatically in recent years. ...

  14. Steady state compact toroidal plasma production

    DOEpatents

    Turner, William C. (Livermore, CA)

    1986-01-01

    Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.

  15. Low-cost compact CWDM filter platform

    NASA Astrophysics Data System (ADS)

    Li, Yao; Luo, Christine; Wang, Daoyi; Li, Lingzhi; Li, Jing; Wu, Frank; Tsay, Wei-shin

    2004-04-01

    We discuss recent surge of interests in coarse DWM (CWDM) applications and implied challenges for low cost and compact devices. We show that for further cost-reduction and performance enhancements, an old WDM packaging architecture can be revitalized to address the new compact CWDM (CCWDM) filter challenges. In particular, we demonstrate a CCWDM filter platform and show its use in both an 8-channel Mux/DeMux and a 4-channel OADM applications.

  16. Eye-safe compact scanning LIDAR technology

    Microsoft Academic Search

    Wei Gong; Thomas H. Chyba; Doyle A. Temple

    2007-01-01

    A 1.5-mum eye-safe, 3-D scanning, and compact Mie LIght Detection and Ranging (LIDAR) is presented. The transmitter of the LIDAR is based on a KTA optical parameter oscillator (OPO) resonator. For detecting return signals, an InGaAs APD is used. The all solid-state OPO laser transmitter has the feature of small volume and lightweight, which allows a 165-lb compact eye-safe scanning

  17. Eye-safe compact scanning LIDAR technology

    Microsoft Academic Search

    Wei Gong; Thomas H. Chyba; Doyle A. Temple

    2007-01-01

    A 1.5-?m eye-safe, 3-D scanning, and compact Mie LIght Detection and Ranging (LIDAR) is presented. The transmitter of the LIDAR is based on a KTA optical parameter oscillator (OPO) resonator. For detecting return signals, an InGaAs APD is used. The all solid-state OPO laser transmitter has the feature of small volume and lightweight, which allows a 165-lb compact eye-safe scanning

  18. Compact toroid formation, compression, and acceleration

    Microsoft Academic Search

    J. H. Degnan; R. E. Peterkin; G. P. Baca; J. D. Beasona; D. E. Bell; M. E. Dearborn; D. Dietz; M. R. Douglas; S. E. Englert; T. J. Englert; K. E. Hackett; J. H. Holmes; T. W. Hussey; G. F. Kiuttu; F. M. Lehr; G. J. Marklin; B. W. Mullins; D. W. Price; N. F. Roderick; E. L. Ruden; C. R. Sovinec; P. J. Turchi; G. Bird; S. K. Coffey; S. W. Seiler; Y. G. Chen; D. Gale; J. D. Graham; M. Scott; W. Sommars

    1993-01-01

    Research on forming, compressing, and accelerating milligram-range compact toroids using a meter diameter, two-stage, puffed gas, magnetic field embedded coaxial plasma gun is described. The compact toroids that are studied are similar to spheromaks, but they are threaded by an inner conductor. This research effort, named marauder (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation), is not a

  19. Compact toroid formation, compression, and acceleration

    Microsoft Academic Search

    J. H. Degnan; R. E. Peterkin Jr.; G. P. Baca; J. D. Beason; D. E. Bell; M. E. Dearborn; D. Dietz; M. R. Douglas; S. E. Englert; T. J. Englert; K. E. Hackett; J. H. Holmes; T. W. Hussey; G. F. Kiuttu; F. M. Lehr; B. W. Mullins; D. W. Price; N. F. Roderick; E. L. Ruden; C. R. Sovinec; P. J. Turchi; G. Bird; S. K. Coffey; S. W. Seiler; Y. G. Chen; D. Gale; J. D. Graham; M. Scott; W. Sommars

    1993-01-01

    Research on forming, compressing, and accelerating milligram-range compact toroids using a meter diameter, two-stage, puffed gas, magnetic field embedded coaxial plasma gun is described. The compact toroids that are studied are similar to spheromaks, but they are threaded by an inner conductor. This research effort, named MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation), is not a

  20. Topologies for compact compensated pulsed alternators

    Microsoft Academic Search

    W. A. Walls; M. Driga

    2001-01-01

    Increasing the compactness of compensated pulsed alternators (compulsators) has been an ongoing effort at The University of Texas Center for Electromechanics (UT-CEM) since the mid-1980's, when the U. S. Army interest in electric armaments began to emerge in a significant way. Today, the compulsator is the best approach for achieving compact energy storage and pulsed power generation for multi-MJ, multi-GW

  1. Topologies for compact compensated pulsed alternators

    Microsoft Academic Search

    W. A. Walls; M. D. Driga

    2001-01-01

    Increasing the compactness of compensated pulsed alternators (compulsators) has been an ongoing effort supported by the US Army and others since the mid-1980s, when interest in electric armaments began to emerge. Today, the compulsator is the best approach for achieving compact energy storage and pulsed power generation for multi-MJ, multi-GW applications requiring voltages of up to 15-20 kV and discharge

  2. Polynomially Compact-Like Strongly Continuous Semigroups

    Microsoft Academic Search

    Khalid Latrach; J. Martin Paoli

    2004-01-01

    J. R. Cuthbert gave some results about the class of semigroups of operators (T(t))\\u000at0 on a Banach space X which have the property that for some t>0, T(t)–I is compact. Cuthbert's results were extended to various classes of operators generalizing the set of compact operators such as the ideal of Fredholm perturbations or the set of Riesz operators. The

  3. EXPENDITURE OBJECT CODES Other Charges OTHER CHARGES

    E-print Network

    Harms, Kyle E.

    Foundation (NSF) grants). Can only be used during the summer. 6690 Athletic Guarantees: This is the money: Federal grant payments to sponsored students for dependents. 6540 Depreciation: Depreciation of equipment functions. Such expenditures cannot be charged to restricted state or federal grants and contracts

  4. Compaction of Ductile and Fragile Grains

    NASA Astrophysics Data System (ADS)

    Creissac, S.; Pouliquen, O.; Dalloz-Dubrujeaud, B.

    2009-06-01

    The compaction of powders into tablets is widely used in several industries (cosmetics, food, pharmaceutics…). In all these industries, the composition of the initial powder is complex, and the behaviour under compaction is not well known, also the mechanical behaviour of the tablets. The aim of this paper is to understand the behaviour (pressure vs density) of a simplified media made of fragile and ductile powders, varying the relative ratio of each powder. Some compaction experiments were carried out with glass beads (fragile) and Polyethylen Glycol powder (ductile). We observe two typical behaviours, depending on the relative volumic fraction of each component. A transition is pointed out, observing the evolution of the slope of the curve pressure/density. This transition is explained by geometrical considerations during compaction. A model is proposed, based on the assumption that the studied media can be compare to a diphasic material with a continuous phase (the ductile powder) and a discrete phase (the fragile powder). The result of this model is compare to the experimental results of compaction, and give a good prediction of the behaviour of the different mixing, knowing the behaviour of the ductile and the fragile phase separately. These results were also interpreted in terms of Heckel parameter which characterizes the ability of the powder to deform plastically under compaction. Some mechanical tests were also performed to compare the mechanical resitance of the obtained tablets.

  5. Ceramic granule strength variability and compaction behavior

    SciTech Connect

    Glass, S.J.; Ewsuk, K.G.; Readey, M.J.

    1995-08-01

    Diametral compression strength distributions and the compaction behavior and of irregular shape 150--200 {mu}m ceramic granules and uniform-size 210 {mu}m glass spheres were measured to determine how granule strength variability relates to compaction behavior of granular assemblies. High variability in strength, represented by low Weibull modulus values (m<3) was observed for ceramic granules having a distribution of sizes and shapes, and for uniform-size glass spheres. Compaction pressure data were also analyzed using a Weibull distribution function, and the results were very similar to those obtained from the diametral compression strength tests for the same material. This similarity suggests that it may be possible to model granule compaction using a weakest link theory, whereby an assemblage of granules is viewed as the links of a chain, and failure of the weakest granule (i.e., the weakest link) leads to rearrangement and compaction. Additionally, with the use of Weibull statistics, it appears to be possible to infer the variability in strength of individual granules from a simple pressure compaction test, circumventing the tedious task of testing individual granules.

  6. Technology Selections for Cylindrical Compact Fabrication

    SciTech Connect

    Jeffrey A. Phillips

    2010-10-01

    A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.

  7. Surface Charge Density Measurements

    Microsoft Academic Search

    Maciej A. Noras; Apra Pandey

    2010-01-01

    This paper is devoted to the Kelvin probe technique which is noncontacting method for the quantitative evaluation of an electric field, surface potential, and surface charge distribution. It does not change the physical state of the object under test. Lack of contact with the measured object assures that there is no charge transfer between the meter and the tested surface.

  8. Space charge stopband correction

    SciTech Connect

    Huang, Xiaobiao; /Fermilab /Indiana U.; Lee, S.Y.; /Indiana U.

    2005-09-01

    It is speculated that the space charge effect cause beam emittance growth through the resonant envelope oscillation. Based on this theory, we propose an approach, called space charge stopband correction, to reduce such emittance growth by compensation of the half-integer stopband width of the resonant oscillation. It is illustrated with the Fermilab Booster model.

  9. Charge-depletion meter

    SciTech Connect

    Schneider, J.F.

    1984-11-27

    This invention relates to a charge-depletion meter apparatus having a current-to-frequency converter to sense and convert the current drain of a battery source to a digital signal which is divided and then accumulated in a counter. An LCD display unit displays the accumulated charge which is received from the counter.

  10. A compact, all solid-state LC high voltage generator

    NASA Astrophysics Data System (ADS)

    Fan, Xuliang; Liu, Jinliang

    2013-06-01

    LC generator is widely applied in the field of high voltage generation technology. A compact and all solid-state LC high voltage generator based on saturable pulse transformer is proposed in this paper. First, working principle of the generator is presented. Theoretical analysis and circuit simulation are used to verify the design of the generator. Experimental studies of the proposed LC generator with two-stage main energy storage capacitors are carried out. And the results show that the proposed LC generator operates as expected. When the isolation inductance is 27 ?H, the output voltage is 1.9 times larger than the charging voltage on single capacitor. The multiplication of voltages is achieved. On the condition that the primary energy storage capacitor is charged to 857 V, the output voltage of the generator can reach to 59.5 kV. The step-up ratio is nearly 69. When self breakdown gas gap switch is used as main switch, the rise time of the voltage pulse on load resistor is 8.7 ns. It means that the series-wound inductance in the discharging circuit is very small in this system. This generator can be employed in two different applications.

  11. A compact, all solid-state LC high voltage generator.

    PubMed

    Fan, Xuliang; Liu, Jinliang

    2013-06-01

    LC generator is widely applied in the field of high voltage generation technology. A compact and all solid-state LC high voltage generator based on saturable pulse transformer is proposed in this paper. First, working principle of the generator is presented. Theoretical analysis and circuit simulation are used to verify the design of the generator. Experimental studies of the proposed LC generator with two-stage main energy storage capacitors are carried out. And the results show that the proposed LC generator operates as expected. When the isolation inductance is 27 ?H, the output voltage is 1.9 times larger than the charging voltage on single capacitor. The multiplication of voltages is achieved. On the condition that the primary energy storage capacitor is charged to 857 V, the output voltage of the generator can reach to 59.5 kV. The step-up ratio is nearly 69. When self breakdown gas gap switch is used as main switch, the rise time of the voltage pulse on load resistor is 8.7 ns. It means that the series-wound inductance in the discharging circuit is very small in this system. This generator can be employed in two different applications. PMID:23822362

  12. Charging Black Saturn?

    E-print Network

    Brenda Chng; Robert Mann; Eugen Radu; Cristian Stelea

    2008-10-28

    We construct new charged static solutions of the Einstein-Maxwell field equations in five dimensions via a solution generation technique utilizing the symmetries of the reduced Lagrangian. By applying our method on the multi-Reissner-Nordstrom solution in four dimensions, we generate the multi-Reissner-Nordstrom solution in five dimensions. We focus on the five-dimensional solution describing a pair of charged black objects with general masses and electric charges. This solution includes the double Reissner-Nordstrom solution as well as the charged version of the five-dimensional static black Saturn. However, all the black Saturn configurations that we could find present either a conical singularity or a naked singularity. We also obtain a non-extremal configuration of charged black strings that reduces in the extremal limit to a Majumdar-Papapetrou like solution in five dimensions.

  13. On the phase structure and thermodynamic geometry of R-charged black holes

    Microsoft Academic Search

    Anurag Sahay; Tapobrata Sarkar; Gautam Sengupta

    2010-01-01

    We study the phase structure and equilibrium state space geometry of R-charged black holes in D = 5, 4 and 7 and the corresponding rotating D3, M2 and M5 branes. For various charge configurations of the compact black holes in the canonical ensemble we demonstrate new liquid-gas\\u000a like phase coexistence behaviour culminating in second order critical points. The critical exponents

  14. Classification of solar cells according to mechanisms of charge separation and charge collection.

    PubMed

    Kirchartz, Thomas; Bisquert, Juan; Mora-Sero, Ivan; Garcia-Belmonte, Germà

    2015-02-14

    In the last decade, photovoltaics (PV) has experienced an important transformation. Traditional solar cells formed by compact semiconductor layers have been joined by new kinds of cells that are constituted by a complex mixture of organic, inorganic and solid or liquid electrolyte materials, and rely on charge separation at the nanoscale. Recently, metal organic halide perovskites have appeared in the photovoltaic landscape showing large conversion efficiencies, and they may share characteristics of the two former types. In this paper we provide a general description of the photovoltaic mechanisms of the single absorber solar cell types, combining all-inorganic, hybrid and organic cells into a single framework. The operation of the solar cell relies on a number of internal processes that exploit internal charge separation and overall charge collection minimizing recombination. There are two main effects to achieve the required efficiency, first to exploit kinetics at interfaces, favouring the required forward process, and second to take advantage of internal electrical fields caused by a built-in voltage and by the distribution of photogenerated charges. These principles represented by selective contacts, interfaces and the main energy diagram, form a solid base for the discussion of the operation of future types of solar cells. Additional effects based on ferroelectric polarization and ionic drift provide interesting prospects for investigating new PV effects mainly in the perovskite materials. PMID:25586862

  15. Entomology and Nematology Academic Learning Compact 1. Academic Learning Compact for a major in Entomology & Nematology B.S.

    E-print Network

    Jawitz, James W.

    1 Entomology and Nematology Academic Learning Compact 1. Academic Learning Compact for a major in Entomology & Nematology B.S. 2. What are Academic Learning Compacts? Academic Learning Compacts follow the prescribed course of study. UF is required to assess student achievement in these Student

  16. taking charge : optimizing urban charging infrastructure for shared electric vehicles

    E-print Network

    Subramani, Praveen

    2012-01-01

    This thesis analyses the opportunities and constraints of deploying charging infrastructure for shared electric vehicles in urban environments. Existing electric vehicle charging infrastructure for privately owned vehicles ...

  17. Trampling increases soil compaction; soil compaction depresses vigor of Andropogon gerardii

    Microsoft Academic Search

    PATRICK MCNEARNEY; JUSTIN RILEY; ALAN WENNERSTEN

    The soil of the prairie is never static; it is constantly affected by and affecting its inhabitant flora and fauna. Many interactions, including the scientific observer's movement on the prairie, have an impact on the quality of the soil. This study examines the compaction that comes about from human foot traffic and the effect of soil compaction on the germination

  18. Role of electric charge in shaping equilibrium configurations of fluid tori encircling black holes

    SciTech Connect

    Kovar, Jiri; Slany, Petr; Stuchlik, Zdenek; Karas, Vladimir; Cremaschini, Claudio; Miller, John C. [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava Bezrucovo nam. 13, CZ-74601 Opava (Czech Republic); Astronomical Institute, Academy of Sciences, Bocni II, CZ-14131 Prague (Czech Republic); SISSA and INFN, Via Bonomea 265, I-34136 Trieste (Italy); SISSA and INFN, Via Bonomea 265, I-34136 Trieste, Italy and Department of Physics (Astrophysics), University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)

    2011-10-15

    Astrophysical fluids may acquire nonzero electrical charge because of strong irradiation or charge separation in a magnetic field. In this case, electromagnetic and gravitational forces may act together and produce new equilibrium configurations, which are different from the uncharged ones. Following our previous studies of charged test particles and uncharged perfect fluid tori encircling compact objects, we introduce here a simple test model of a charged perfect fluid torus in strong gravitational and electromagnetic fields. In contrast to ideal magnetohydrodynamic models, we consider here the opposite limit of negligible conductivity, where the charges are tied completely to the moving matter. This is an extreme limiting case which can provide a useful reference against which to compare subsequent more complicated astrophysically motivated calculations. To clearly demonstrate the features of our model, we construct three-dimensional axisymmetric charged toroidal configurations around Reissner-Nordstroem black holes and compare them with equivalent configurations of electrically neutral tori.

  19. Counterintuitive compaction behavior of clopidogrel bisulfate polymorphs.

    PubMed

    Khomane, Kailas S; More, Parth K; Bansal, Arvind K

    2012-07-01

    Being a density violator, clopidogrel bisulfate (CLP) polymorphic system (forms I and II) allows us to study individually the impact of molecular packing (true density) and thermodynamic properties such as heat of fusion on the compaction behavior. These two polymorphs of CLP were investigated for in-die and out-of-die compaction behavior using CTC profile, Heckel, and Walker equations. Compaction studies were performed on a fully instrumented rotary tabletting machine. Detailed examinations of the molecular packing of each form revealed that arrangement of the sulfate anion differs significantly in both crystal forms, thus conferring different compaction behavior to two forms. Close cluster packing of molecules in form I offers a rigid structure, which has poor compressibility and hence resists deformation under compaction pressure. This results into lower densification, higher yield strength, and mean yield pressure, as compared with form II at a given pressure. However, by virtue of higher bonding strength, form I showed superior tabletability, despite its poor compressibility and deformation behavior. Form I, having higher true density and lower heat of fusion showed higher bonding strength. Hence, true density and not heat of fusion can be considered predictor of bonding strength of the pharmaceutical powders. PMID:22488254

  20. A constant current high voltage capacitor charging power supply for pulsed power applications

    Microsoft Academic Search

    G.-H. Rim; I.-W. Jeong; Y.-W. Choi; H.-J. Ryoo; J.-S. Kim; K.-H. Kim; S.-P. Lee; H.-K. Chang

    2001-01-01

    Summary form only given. Various industry applications such as lasers, accelerators, plasma source ion implantations and non-thermal pollution gas treatment need high voltage high repetition rate pulsed power supplies. This paper presents a compact capacitor charging power supply for gas treatment. It consists of a three-phase rectifier with soft starting, a three phase IGBT inverter, three high frequency transformers and

  1. Relativistic charged particle in the dipole-sphere configuration. II. General tilted surface orbits.

    SciTech Connect

    Gopinath, K.S.; Kennedy, D.C. [Florida State Univ., Tallahassee, FL (United States). Dept. of Physics

    1997-03-01

    Relativistic charged particle orbits on a rotating sphere threaded by an intense magnetic dipole field are examined. Generalizing the results of the first paper (I), the dipole and rotational axes have arbitrary relative tilt. For ultra-intense magnetic fields characteristic of compact astrophysical bodies, the classical and semiclassical results are not greatly changed for moderate rotation rates. 4 refs., 4 figs.

  2. Spacecraft Habitation Systems, Water Recovery and Waste Active Charged Particle and Neutron Radiation Measurement

    E-print Network

    SBIR SBIR 62 63 I Spacecraft Habitation Systems, Water Recovery and Waste Management Active Charged, High Output Plastic Melt Waste Compactor (HEHO-PMWC) is a trash dewatering and volume reduction system that uses heat melt compaction to remove nearly 100% of water from trash and reduce the volume by up to 11

  3. Generating charge from diffeomorphisms

    NASA Astrophysics Data System (ADS)

    Hansen, James; Kraus, Per

    2006-12-01

    We unravel some subtleties involving the definition of sphere angular momentum charges in AdSq × Sp spacetimes, or equivalently, R-symmetry charges in the dual boundary CFT. In the AdS3 context, it is known that charges can be generated by coordinate transformations, even though the underlying theory is diffeomorphism invariant. This is the bulk version of spectral flow in the boundary CFT. We trace this behavior back to special properties of the p-form field strength supporting the solution, and derive the explicit formulas for angular momentum charges. This analysis also reveals the higher dimensional origin of three dimensional Chern-Simons terms and of chiral anomalies in the boundary theory.

  4. Charged Schrodinger black holes

    E-print Network

    Adams, Allan

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

  5. International aeronautical user charges

    E-print Network

    Odoni, Amedeo R.

    1985-01-01

    Introduction: 1.1 BACKGROUND AND MOTIVATION Very few issues relating to the international air transportation industry are today as divisive as those pertaining to user charges imposed at international airports and enroute ...

  6. Charged Particle Flux Sensor

    NASA Technical Reports Server (NTRS)

    Gregory, D. A.; Stocks, C. D.

    1983-01-01

    Improved version of Faraday cup increases accuracy of measurements of flux density of charged particles incident along axis through collection aperture. Geometry of cone-and-sensing cup combination assures most particles are trapped.

  7. Generating Charge from Diffeomorphisms

    E-print Network

    James Hansen; Per Kraus

    2006-09-18

    We unravel some subtleties involving the definition of sphere angular momentum charges in AdS_q \\times S^p spacetimes, or equivalently, R-symmetry charges in the dual boundary CFT. In the AdS_3 context, it is known that charges can be generated by coordinate transformations, even though the underlying theory is diffeomorphism invariant. This is the bulk version of spectral flow in the boundary CFT. We trace this behavior back to special properties of the p-form field strength supporting the solution, and derive the explicit formulas for angular momentum charges. This analysis also reveals the higher dimensional origin of three dimensional Chern-Simons terms and of chiral anomalies in the boundary theory.

  8. Electrically charged targets

    DOEpatents

    Goodman, Ronald K. (Livermore, CA); Hunt, Angus L. (Alamo, CA)

    1984-01-01

    Electrically chargeable laser targets and method for forming such charged targets in order to improve their guidance along a predetermined desired trajectory. This is accomplished by the incorporation of a small amount of an additive to the target material which will increase the electrical conductivity thereof, and thereby enhance the charge placed upon the target material for guidance thereof by electrostatic or magnetic steering mechanisms, without adversely affecting the target when illuminated by laser energy.

  9. Shaped charge well perforator

    SciTech Connect

    Mcphee, W.A.

    1983-06-14

    A shaped charge unit is claimed for well perforating having a outer shell with an internal cavity formed therein. An explosive charge material conforms in exterior shape with the inside surface of the cavity and is retained in place by a conical liner of nonexplosive material. The interior shape of the cavity is such that an increased amount of explosive material is provided in a circumferential channel located proximate to the periphery of the base of the conical liner.

  10. The London Congestion Charge

    Microsoft Academic Search

    Jonathan Leape

    2006-01-01

    By the 1990s, the average speed of trips across London was below that at the beginning of the twentieth century—before the car was introduced—and by the end of that decade, public concern over levels of traffic congestion was high. In early 2003, London imposed a congestion charge—a daily charge for driving or parking a vehicle on public roads within central

  11. Particle-Charge Spectrometer

    NASA Technical Reports Server (NTRS)

    Fuerstenau, Stephen; Wilson, Gregory R.

    2008-01-01

    An instrument for rapidly measuring the electric charges and sizes (from approximately 1 to approximately 100 micrometers) of airborne particles is undergoing development. Conceived for monitoring atmospheric dust particles on Mars, instruments like this one could also be used on Earth to monitor natural and artificial aerosols in diverse indoor and outdoor settings for example, volcanic regions, clean rooms, powder-processing machinery, and spray-coating facilities. The instrument incorporates a commercially available, low-noise, ultrasensitive charge-sensing preamplifier circuit. The input terminal of this circuit--the gate of a field-effect transistor--is connected to a Faraday-cage cylindrical electrode. The charged particles of interest are suspended in air or other suitable gas that is made to flow along the axis of the cylindrical electrode without touching the electrode. The flow can be channeled and generated by any of several alternative means; in the prototype of this instrument, the gas is drawn along a glass capillary tube (see upper part of figure) coaxial with the electrode. The size of a particle affects its rate of acceleration in the flow and thus affects the timing and shape of the corresponding signal peak generated by the charge-sensing amplifier. The charge affects the magnitude (and thus also the shape) of the signal peak. Thus, the signal peak (see figure) conveys information on both the size and electric charge of a sensed particle. In experiments thus far, the instrument has been found to be capable of measuring individual aerosol particle charges of magnitude greater than 350 e (where e is the fundamental unit of electric charge) with a precision of +/- 150 e. The instrument can sample particles at a rate as high as several thousand per second.

  12. Shock compaction of high- Tc superconductors

    SciTech Connect

    Weir, S.T.; Nellis, W.J.; McCandless, P.C.; Brocious, W.F. (Lawrence Livermore National Lab., CA (USA)); Seaman, C.L.; Early, E.A.; Maple, M.B. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics); Kramer, M.J. (Ames Lab., IA (USA)); Syono, Y.; Kikuchi, M. (Tohoku Univ., Sendai (Japan))

    1990-09-01

    We present the results of shock compaction experiments on high-{Tc} superconductors and describe the way in which shock consolidation addresses critical problems concerning the fabrication of high J{sub c} bulk superconductors. In particular, shock compaction experiments on YBa{sub 2}Cu{sub 3}O{sub 7} show that shock-induced defects can greatly increase intragranular critical current densities. The fabrication of crystallographically aligned Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} samples by shock-compaction is also described. These experiments demonstrate the potential of the shock consolidation method as a means for fabricating bulk high-{Tc} superconductors having high critical current densities.

  13. Capability enhancement in compact digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Qu, Weijuan; Wen, Yongfu; Wang, Zhaomin; Yang, Fang; Asundi, Anand

    2015-03-01

    A compact reflection digital holographic microscopy (DHM) system integrated with the light source and optical interferometer is developed for 3D topographic characterization and real-time dynamic inspection for Microelectromechanical systems (MEMS). Capability enhancement methods in lateral resolution, axial resolving range and large field of view for the compact DHM system are presented. To enhance the lateral resolution, the numerical aperture of a reflection DHM system is analyzed and optimum designed. To enhance the axial resolving range, dual wavelengths are used to extend the measuring range. To enable the large field of view, stitching of the measurement results is developed in the user-friendly software. Results from surfaces structures on silicon wafer, micro-optics on fused silica and dynamic inspection of MEMS structures demonstrate applications of this compact reflection digital holographic microscope for technical inspection in material science.

  14. GRAVITATIONALLY FOCUSED DARK MATTER AROUND COMPACT STARS

    SciTech Connect

    Bromley, Benjamin C., E-mail: bromley@physics.utah.edu [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Room 201, Salt Lake City, UT 84112 (United States)

    2011-12-01

    If dark matter self-annihilates then it may produce an observable signal when its density is high. The details depend on the intrinsic properties of dark matter and how it clusters in space. For example, the density profile of some dark matter candidates may rise steeply enough toward the Galactic Center that self-annihilation may produce detectable {gamma}-ray emission. Here, we discuss the possibility that an annihilation signal arises near a compact object (e.g., neutron star or black hole) even when the density of dark matter in the neighborhood of the object is uniform. Gravitational focusing produces a local enhancement of density with a profile that falls off approximately as the inverse square-root of distance from the compact star. While geometric dilution may overwhelm the annihilation signal from this local enhancement, magnetic fields tied to the compact object can increase the signal's contrast relative to the background.

  15. Settlement of footing on compacted ash bed

    SciTech Connect

    Ramasamy, G.; Pusadkar, S.S. [IIT Roorkee, Roorkee (India). Dept. of Civil Engineering

    2007-11-15

    Compacted coal ash fills exhibit capillary stress due to contact moisture and preconsolidation stress due to the compaction process. As such, the conventional methods of estimating settlement of footing on cohesionless soils based on penetration tests become inapplicable in the case of footings on coal ash fills, although coal ash is also a cohesionless material. Therefore, a method of estimating load-settlement behavior of footings resting on coal ash fills accounting for the effect of capillary and preconsolidation stresses is presented here. The proposed method has been validated by conducting plate load tests on laboratory prepared compacted ash beds and comparing the observed and predicted load-settlement behavior. Overestimation of settlement greater than 100% occurs when capillary and preconsolidation stresses are not accounted for, as is the case in conventional methods.

  16. Anisotropic Compact stars with variable cosmological constant

    E-print Network

    Sk. Monowar Hossein; Farook Rahaman; Jayanta Naskar; Mehedi Kalam; Saibal Ray

    2012-11-22

    Recently the small value of the cosmological constant and its ability to accelerate the expansion of the Universe is of great interest. We discuss the possibility of forming of anisotropic compact stars from this cosmological constant as one of the competent candidates of dark energy. For this purpose we consider the analytical solution of Krori and Barua metric. We take the radial dependence of cosmological constant and check all the regularity conditions, TOV equations, stability and surface redshift of the compact stars. It has been shown as conclusion that this model is valid for any compact star and we have cited $4U 1820-30$ as a specific example of that kind of star.

  17. Impacts by Compact Ultra Dense Objects

    NASA Astrophysics Data System (ADS)

    Birrell, Jeremey; Labun, Lance; Rafelski, Johann

    2012-03-01

    We propose to search for nuclear density or greater compact ultra dense objects (CUDOs), which could constitute a significant fraction of the dark matter [1]. Considering their high density, the gravitational tidal forces are significant and atomic-density matter cannot stop an impacting CUDO, which punctures the surface of the target body, pulverizing, heating and entraining material near its trajectory through the target [2]. Because impact features endure over geologic timescales, the Earth, Moon, Mars, Mercury and large asteroids are well-suited to act as time-integrating CUDO detectors. There are several potential candidates for CUDO structure such as strangelet fragments or more generally dark matter if mechanisms exist for it to form compact objects. [4pt] [1] B. J. Carr, K. Kohri, Y. Sendouda, & J.'i. Yokoyama, Phys. Rev. D81, 104019 (2010). [0pt] [2] L. Labun, J. Birrell, J. Rafelski, Solar System Signatures of Impacts by Compact Ultra Dense Objects, arXiv:1104.4572.

  18. Activation analysis of the compact ignition tokamak

    SciTech Connect

    Selcow, E.C.

    1986-01-01

    The US fusion program has completed the conceptual design of a compact tokamak device that achieves ignition. The high neutron wall loadings associated with this compact deuterium-tritium-burning device indicate that radiation-related issues may be significant considerations in the overall system design. Sufficient shielding will be requied for the radiation protection of both reactor components and occupational personnel. A close-in igloo shield has been designed around the periphery of the tokamak structure to permit personnel access into the test cell after shutdown and limit the total activation of the test cell components. This paper describes the conceptual design of the igloo shield system and discusses the major neutronic concerns related to the design of the Compact Ignition Tokamak.

  19. Discovering Nearby Compact Objects with Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Di Stefano, Rosanne; Primini, F.

    2013-04-01

    Within a kiloparsec of Earth there are more than 10 million black holes, and ten times as many neutron stars. These compact objects have proved difficult to discover, and only a handful have been identified. Black holes and neutron stars regularly serve as gravitational lenses, however. We report on our efforts to use existing and new data to use their action as lenses to discover them. For example, several percent of the 2000 lensing events found by the OGLE and MOA teams each year are generated by nearby compact objects. We describe how this optical data, combined with x-ray data, including some to be collected by new Chandra programs, can be used to identify those events caused by compact objects. If this approach is successful, direct mass measurements will be carried out on a regular basis.

  20. Anisotropic compact stars in f( T) gravity

    NASA Astrophysics Data System (ADS)

    Abbas, G.; Kanwal, Afshan; Zubair, M.

    2015-06-01

    This paper deals with the theoretical modeling of anisotropic compact stars in the framework of f( T) theory of gravity, where T is torsion scalar. To this end, we have used the exact solutions of Krori and Barua metric to a static spherically symmetric metric. The unknown constants involved in the Krori and Barua metric have been specified by using the masses and radii of compact stars 4 U1820-30, Her X-1, SAX J 1808-3658. The physical properties of these stars have been analyzed in the framework of f( T) theory. In this setting, we have checked the anisotropic behavior, regularity conditions, stability and surface redshift of the compact stars.

  1. Anisotropic compact stars in f( G) gravity

    NASA Astrophysics Data System (ADS)

    Abbas, G.; Momeni, D.; Aamir Ali, M.; Myrzakulov, R.; Qaisar, S.

    2015-06-01

    This paper is devoted to study the possibility of forming anisotropic compact stars in modified Gauss-Bonnet, namely called as f( G) theory of gravity which is one of the strong candidates, responsible for the accelerated expansion of the universe. For this purpose, we have used analytical solution of Krori and Barua metric to the Einstein field equations with anisotropic form of matter and power law model of f( G) gravity. To determine the unknown constants in Krori and Barua metric, we have used the sample of compact stars, 4 U1820-30, Her X-1, SAX J 1808-3658. The physical behavior of these stars have been analyzed with the observational data. In this setting, we have checked all the regularity conditions and stability of the compact stars 4 U1820-30, Her X-1, SAX J 1808-3658.

  2. Proppant charge and method

    SciTech Connect

    Glaze, O.H.; Underdown, D.R.

    1987-05-12

    A pre-cured proppant charge is described for propping a fracture in a subterranean well. The pre-cured proppant charge is precured with a thermoset. Phenolic resin thereon is cured to completion during a substantially liquid saturation-free cure thereof prior to injection in the subterranean well. The precured proppant comprises: free-flowing sand particles coated with the thermoset, phenolic resin thereon; the thermoset, phenolic resin coating being one which, when it is the coating on the particles of a proppant charge, produces a charge wherein at least one of: the Permeability Ratio thereof throughout a closure stress range of about 6,000 to 14,000 p.s.i., is greater than that of a charge of uncoated sand particles having substantially the same particle size distribution; or the Permeability Ratio thereof throughout the stress range of about 2,000 to 10,000 p.s.i. is at least about 30 percent that of a sintered bauxite charge of substantially the same particle size, the resin for the coating, prior to thermosetting.

  3. Perforating gun charge carrier improvements

    SciTech Connect

    Vann, R.R.; Colle, E.A. Jr.

    1986-07-08

    This patent describes a perforating gun for perforating a casing located downhole in a cased borehole, the gun having a housing, shaped charges in the housing spaced from one another and connected to a detonation means, each shaped charge having a flange means on one end of a body portion, the other end of the body portion being the detonator end, the combination with the housing, charges, and detonation means of a charge carrier assembly. The charge carrier assembly comprises charge holders connected together along the longitudinal axis of the gun; each charge holder describes a polyhedron, each polyhedron being described by relatively thin wall surfaces joined together by lateral edges which extend parallel to the axial centerline of the gun and provide opposed fasteners for the shaped charge. Each charge holder has lateral faces, one of the faces is apertured to telescopingly receive a shaped charge therewithin, adjacent charge holders have means for orienting the shaped charges of alternate charge holders in different radial directions; and means for capturing a shaped charge within an aperture of a charge holder. The body portion of the shaped charge is received within the aperture of the charge holder with the flange means of the shaped charge abutting a lateral of the charge holder, and having the opposed fasteners extending towards an opposed fastener located on an alternate charge holder to capture the flange between two opposed fasteners and the lateral face of the charge holder so that the inner detonator end of the charge is positioned near the geometrical center of the charge holder.

  4. Compact Focal Plane Assembly for Planetary Science

    NASA Technical Reports Server (NTRS)

    Brown, Ari; Aslam, Shahid; Huang, Wei-Chung; Steptoe-Jackson, Rosalind

    2013-01-01

    A compact radiometric focal plane assembly (FPA) has been designed in which the filters are individually co-registered over compact thermopile pixels. This allows for construction of an ultralightweight and compact radiometric instrument. The FPA also incorporates micromachined baffles in order to mitigate crosstalk and low-pass filter windows in order to eliminate high-frequency radiation. Compact metal mesh bandpass filters were fabricated for the far infrared (FIR) spectral range (17 to 100 microns), a game-changing technology for future planetary FIR instruments. This fabrication approach allows the dimensions of individual metal mesh filters to be tailored with better than 10- micron precision. In contrast, conventional compact filters employed in recent missions and in near-term instruments consist of large filter sheets manually cut into much smaller pieces, which is a much less precise and much more labor-intensive, expensive, and difficult process. Filter performance was validated by integrating them with thermopile arrays. Demonstration of the FPA will require the integration of two technologies. The first technology is compact, lightweight, robust against cryogenic thermal cycling, and radiation-hard micromachined bandpass filters. They consist of a copper mesh supported on a deep reactive ion-etched silicon frame. This design architecture is advantageous when constructing a lightweight and compact instrument because (1) the frame acts like a jig and facilitates filter integration with the FPA, (2) the frame can be designed so as to maximize the FPA field of view, (3) the frame can be simultaneously used as a baffle for mitigating crosstalk, and (4) micron-scale alignment features can be patterned so as to permit high-precision filter stacking and, consequently, increase the filter bandwidth and sharpen the out-of-band rolloff. The second technology consists of leveraging, from another project, compact and lightweight Bi0.87Sb0.13/Sb arrayed thermopiles. These detectors consist of 30-layer thermopiles deposited in series upon a silicon nitride membrane. At 300 K, the thermopile arrays are highly linear over many orders of magnitude of incident IR power, and have a reported specific detectivity that exceeds the requirements imposed on future mission concepts. The bandpass filter array board is integrated with a thermopile array board by mounting both boards on a machined aluminum jig.

  5. A compact, portable pulse forming line

    NASA Astrophysics Data System (ADS)

    Xia, Liansheng; Zhang, Huang; Shi, Jinshui; Zhang, Linwen; Deng, Jianjun; Liu, Hanxing; Cao, Minhe

    2008-08-01

    Some research has been done on making a compact, portable pulse forming line. A kind of ceramic based on SrTiO3 is used as the dielectric of the planar pulse forming line. The ceramic's dielectric constant is around 300 and can store more energy than water with the same volume. However, it is not easy to manufacture the large ceramic bulk but we did successfully manufacture 80×10×6 cm3 ceramic bulks. Using this kind of ceramic bulk as the dielectric, we successfully made a compact, portable line that generated a voltage pulse up to 150 kV with a duration of about 92 ns.

  6. COMPACT ACCELERATOR CONCEPT FOR PROTON THERAPY

    SciTech Connect

    Caporaso, G; Sampayan, S; Chen, Y; Harris, J; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Nunnally, W; Paul, A; Poole, B; Rhodes, M; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J

    2006-08-18

    A new type of compact induction accelerator is under development at the Lawrence Livermore National Laboratory that promises to increase the average accelerating gradient by at least an order of magnitude over that of existing induction machines. The machine is based on the use of high gradient vacuum insulators, advanced dielectric materials and switches and is being developed as a compact flash x-ray radiography source. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be presented.

  7. Momentum compaction and phase slip factor

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2010-10-01

    Section 2.3.11 of the Handbook of Accelerator Physics and Engineering on Landau damping is updated. The slip factor and its higher orders are given in terms of the various orders of the momentum compaction. With the aid of a simplified FODO lattice, formulas are given for the alteration of the lower orders of the momentum compaction by various higher multipole magnets. The transition to isochronicity is next demonstrated. Formulas are given for the extraction of the first three orders of the slip factor from the measurement of the synchrotron tune while changing the rf frequency. Finally bunch-length compression experiments in semi-isochronous rings are reported.

  8. Quantizations of compact Lie group actions

    NASA Astrophysics Data System (ADS)

    Huru, Hilja L.; Lychagin, Valentin V.

    2014-06-01

    In this paper we describe quantizations in the monoidal categories of unitary representations of compact connected Lie groups. For the n-dimensional torus T we show that the set Q(T) of quantizations is isomorphic to the (n2)-dimensional torus. For connected compact Lie groups G of rank n, we get the result that the set QE(G) of extendible quantizations of G-modules is isomorphic to the set of quantizations of its maximal torus T invariant under action by its Weyl group. For all these cases we give explicit formulae for quantizations and apply these to quantize Hilbert-Schmidt operators.

  9. Gravitational waves from coalescing compact binaries

    E-print Network

    Eric Poisson

    1995-08-07

    This article is intended to provide a pedagogical account of issues related to, and recent work on, gravitational waves from coalescing compact binaries (composed of neutron stars and/or black holes). These waves are the most promising for kilometer-size interferometric detectors such as LIGO and VIRGO. Topics discussed include: interferometric detectors and their noise; coalescing compact binaries and their gravitational waveforms; the technique of matched filtering for signal detection and measurement; waveform calculations in post-Newtonian theory and in the black-hole perturbation approach; and the accuracy of the post-Newtonian expansion.

  10. Entropic attraction: Polymer compaction and expansion induced by nano-particles in confinement

    NASA Astrophysics Data System (ADS)

    Liao, Guo-Jun; Chien, Fan-Tso; Luzhbin, Dmytro; Chen, Yeng-Long

    2015-05-01

    We investigated nanoparticle (NP)-induced coil-to-globule transition of a semi-flexible polymer in a confined suspension of ideal NP using Langevin dynamics. DNA molecules are often found to be highly compact, bound with oppositely charged proteins in a crowded environment within cells and viruses. Recent studies found that high concentration of electrostatically neutral NP also condenses DNA due to entropically induced depletion attraction between DNA segments. Langevin dynamics simulations with a semi-flexible chain under strong confinement were performed to investigate the competition between NP-induced monomer-monomer and monomer-wall attraction under different confinement heights and NP volume fractions. We found that whether NP induce polymer segments to adsorb to the walls and swell or to attract one another and compact strongly depends on the relative strength of the monomer-wall and the NP-wall interactions.

  11. Compaction Scale Up and Optimization of Cylindrical Fuel Compacts for the Next Generation Nuclear Plant

    SciTech Connect

    Jeffrey J. Einerson; Jeffrey A. Phillips; Eric L. Shaber; Scott E. Niedzialek; W. Clay Richardson; Scott G. Nagley

    2012-10-01

    Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of designed experiments have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel. Results from these experiments are included. The scale-up effort is nearing completion with the process installed and operational using nuclear fuel materials. The process is being certified for manufacture of qualification test fuel compacts for the AGR-5/6/7 experiment at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL).

  12. Differential compaction behaviour of roller compacted granules of clopidogrel bisulphate polymorphs.

    PubMed

    Khomane, Kailas S; Bansal, Arvind K

    2014-09-10

    In the present work, in-die and out-of-die compaction behaviour of dry-granulated powders of clopidogrel bisulphate (CLP) polymorphs, form I and form II, was investigated using a fully instrumented rotary tablet press. Each polymorph was compacted at three different roller pressures [70.3 (S1), 105.5 (S2) and 140.6 (S3)kgf/cm(2)], and obtained granules were characterized for their physico-mechanical properties. Compaction data were analyzed for out-of-die compressibility, tabletability and compactibility profiles, and in-die Heckel, Kawakita and Walker analysis. The roller compacted granules of both forms showed markedly different tabletting behaviour. Roller pressure exhibited a trend on compaction behaviour of form I granules, whereas, in case of form II, the effect was insignificant. Tabletability of the six granule batches follows the order; I_S1>I_S2>I_S3>II_S1?II_S2?II_S3. In case of form I, the reduced tabletability of the granules compacted at higher roller pressure was attributed to the decreased compressibility and plastic deformation. This was confirmed by compressibility plot and various mathematical parameters derived from Heckel (Py), Kawakita (1/b) and Walker (W) equations. The reduced tabletability of form I granules was due to 'granule hardening' during roller compaction. On the other hand, insignificant effect of roller compaction on tabletting behaviour of form II granules was attributed to brittle fragmentation. The extensive fragmentation of granules offered new 'clean' surfaces and higher contact points that negated the effect of granule hardening. PMID:24971694

  13. Nanoparticle coagulation in fractionally charged and charge fluctuating dusty plasmas

    SciTech Connect

    Nunomura, Shota; Kondo, Michio [Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Shiratani, Masaharu; Koga, Kazunori; Watanabe, Yukio [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 819-0395 (Japan)

    2008-08-15

    The kinetics of nanoparticle coagulation has been studied in fractionally charged and charge fluctuating dusty plasmas. The coagulation occurs when the mutual collision frequency among nanoparticles exceeds their charging and decharging/neutralization frequency. Interestingly, the coagulation is suppressed while a fraction (several percent) of nanoparticles are negatively charged in a plasma, in which stochastic charging plays an important role. A model is developed to predict a phase diagram of the coagulation and its suppression.

  14. FODO-Supercell Based Compact Ring Design with Tunable Momentum Compaction and Optimized Dynamic Aperture

    SciTech Connect

    Sun, Yipeng; /SLAC

    2012-05-11

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and pre-damping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  15. Searches for Fractionally Charged Particles

    SciTech Connect

    Perl, Martin L.; /SLAC; Lee, Eric R.; Loomba, Dinesh; /New Mexico U.

    2012-04-12

    Since the initial measurements of the electron charge were made a century ago, experimenters have faced the persistent question of the existence of elementary particles with charges that are fractional multiples of the electron charge. In this review, we discuss the results of recent searches for these fractionally charged particles.

  16. Safe explosives for shaped charges

    Microsoft Academic Search

    K. J. Scribner; J. O. Davis

    1977-01-01

    It was demonstrated that high-performance shaped charges could be developed using as the explosive charge mixtures of ingredients that are not, by themselves, considered explosives. At least one of the ingredients needed to be a liquid, stored separately, that could be quickly injected into the shaped charge cavity to generate the active explosive. Precision copper shaped charge cones in diameters

  17. A compact streak camera for 150 fs time resolved measurement of bright pulses in ultrafast electron diffraction

    NASA Astrophysics Data System (ADS)

    Kassier, G. H.; Haupt, K.; Erasmus, N.; Rohwer, E. G.; von Bergmann, H. M.; Schwoerer, H.; Coelho, S. M. M.; Auret, F. D.

    2010-10-01

    We have developed a compact streak camera suitable for measuring the duration of highly charged subrelativistic femtosecond electron bunches with an energy bandwidth in the order of 0.1%, as frequently used in ultrafast electron diffraction (UED) experiments for the investigation of ultrafast structural dynamics. The device operates in accumulation mode with 50 fs shot-to-shot timing jitter, and at a 30 keV electron energy, the full width at half maximum temporal resolution is 150 fs. Measured durations of pulses from our UED gun agree well with the predictions from the detailed charged particle trajectory simulations.

  18. Compact Tactile Sensors for Robot Fingers

    NASA Technical Reports Server (NTRS)

    Martin, Toby B.; Lussy, David; Gaudiano, Frank; Hulse, Aaron; Diftler, Myron A.; Rodriguez, Dagoberto; Bielski, Paul; Butzer, Melisa

    2004-01-01

    Compact transducer arrays that measure spatial distributions of force or pressure have been demonstrated as prototypes of tactile sensors to be mounted on fingers and palms of dexterous robot hands. The pressure- or force-distribution feedback provided by these sensors is essential for the further development and implementation of robot-control capabilities for humanlike grasping and manipulation.

  19. Development of a compact cold atom clock

    Microsoft Academic Search

    S. Tremine; S. Guerandel; D. Holleville; A. Clairon; N. Dimarcq

    2004-01-01

    HORACE is a compact cold atom clock where the atoms are cooled inside the microwave interrogation cavity. About 108 atoms can be cooled at kinetic temperatures as low as 2.5 ?K. We report, for the first time, a Ramsey pattern observed with a 14 Hz linewidth and fringe contrast better than 80%. Since this clock is designed for space applications,

  20. Workability in forging of powder metallurgy compacts

    Microsoft Academic Search

    M. Abdel-Rahman; M. N. El-Sheikh

    1995-01-01

    The power metallurgy (PM) technique is now applied widely to many industries and materials. To obtain more reliable PM products, many secondary processes are applied to PM preforms. The problem of deformation and fracture of PM preforms still needs a considerable amount of investigation.In this work, the effect of the relative density on the forming limit of PM compacts in

  1. Compaction and Wear Concerns on Sports Fields.

    ERIC Educational Resources Information Center

    Gillan, John

    1999-01-01

    Describes relatively simple measures athletic-facility managers can use to alleviate the turf destruction and compaction of athletic fields including seed and soil amendments and modifications on team practice. Ways of enhancing surface traction and lessen surface hardness are explored. (GR)

  2. Magnetism in Compact Ultra Dense Objects

    NASA Astrophysics Data System (ADS)

    Ferrer, Efrain J.

    2015-01-01

    This paper summarizes some of the recent results on magnetism in high dense mediums, where the phenomenon of color superconductivity can be present, and its possible implications for the astrophysics of compact objects. The presentation will be organized through the answers to three fundamental questions.

  3. Unified beaming models and compact radio sources

    NASA Astrophysics Data System (ADS)

    Peacock, J. A.

    The basics of relativistic beaming from compact radio sources are reviewed, and unified models to account for this beaming are discussed. The Scheuer-Redhead model, which proved to be incorrect, is reviewed, showing where it went wrong. The Orr-Browne and the Blandford-Rees models are compared and discussed.

  4. Pathway to a Compact SASE FEL Device

    E-print Network

    Dattoli, G; Petrillo, V; Rau, J V; Sabia, E; Spassovsky, I; Biedron, S G; Einstein, J; Milton, S V

    2015-01-01

    Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices.

  5. Trapping of neutrinos in extremely compact stars

    E-print Network

    Zdenek Stuchlik; Martin Urbanec; Gabriel Torok; Stanislav Hledik; Jan Hladik

    2007-01-11

    Trapping of neutrinos in extremely compact stars containing trapped null geodesics is studied. We calculated the ratio of produced to trapped neutrinos in the simplest model of uniform density stars. This gives the upper limit on trapping coefficients in real objects.

  6. Analysis of Technology for Compact Coherent Lidar

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin

    1997-01-01

    In view of the recent advances in the area of solid state and semiconductor lasers has created new possibilities for the development of compact and reliable coherent lidars for a wide range of applications. These applications include: Automated Rendezvous and Capture, wind shear and clear air turbulence detection, aircraft wake vortex detection, and automobile collision avoidance. The work performed by the UAH personnel under this Delivery Order, concentrated on design and analyses of a compact coherent lidar system capable of measuring range and velocity of hard targets, and providing air mass velocity data. The following is the scope of this work. a. Investigate various laser sources and optical signal detection configurations in support of a compact and lightweight coherent laser radar to be developed for precision range and velocity measurements of hard and fuzzy targets. Through interaction with MSFC engineers, the most suitable laser source and signal detection technique that can provide a reliable compact and lightweight laser radar design will be selected. b. Analyze and specify the coherent laser radar system configuration and assist with its optical and electronic design efforts. Develop a system design including its optical layout design. Specify all optical components and provide the general requirements of the electronic subsystems including laser beam modulator and demodulator drivers, detector electronic interface, and the signal processor. c. Perform a thorough performance analysis to predict the system measurement range and accuracy. This analysis will utilize various coherent laser radar sensitivity formulations and different target models.

  7. Physics of compact stellarators* S. P. Hirshman,

    E-print Network

    Physics of compact stellarators* S. P. Hirshman, D. A. Spong, J. C. Whitson, B. Nelson, D. B. Batchelor, J. F. Lyon, and R. Sanchez Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 A. Brooks, G. Y.-Fu, R. J. Goldston, L-P. Ku, D. A. Monticello, H. Mynick, G. H. Neilson, N. Pomphrey, M

  8. Compact microwave cavity for hydrogen atomic clock

    NASA Technical Reports Server (NTRS)

    Zhang, Dejun; Zhang, Yan; Fu, Yigen; Zhang, Yanjun

    1992-01-01

    A summary is presented that introduces the compact microwave cavity used in the hydrogen atomic clock. Special emphasis is placed on derivation of theoretical calculating equations of main parameters of the microwave cavity. A brief description is given of several methods for discriminating the oscillating modes. Experimental data and respective calculated values are also presented.

  9. Compact Apparatus For Growth Of Protein Crystals

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Miller, Teresa Y.

    1991-01-01

    Compact apparatus proposed specifically for growth of protein crystals in microgravity also used in terrestrial laboratories to initiate and terminate growth at prescribed times automatically. Has few moving parts. Also contains no syringes difficult to clean, load, and unload and introduces contaminant silicon grease into crystallization solution. After growth of crystals terminated, specimens retrieved and transported simply.

  10. ccsd00001059 Continuous melting of compact polymers

    E-print Network

    ccsd­00001059 (version 1) : 26 Jan 2004 Continuous melting of compact polymers Jesper Lykke relevant for polymers on surfaces, such as DNA adsorbed on a lipid bilayer. We predict a continuous melting transition, and compute exact values of critical exponents at the transition point. Condensed phases

  11. Compact imaging system for GEM detectors

    Microsoft Academic Search

    Tomohisa Uchida; Masahiro Ikeno; Takahisa Koike; Kouichi Miyama; Takeshi Murakami; Eiichi Nakano; Hideki Ohwada; Michiko Sekimoto; Masayoshi Shoji; Manobu Tanaka; Shoji Uno; Masaki Wada

    2010-01-01

    We have developed a compact imaging system for GEM detectors, which is applied to thermal neutron imaging. A GEM chamber and a readout board are integrated into one device. The detector is connected to a readout PC with Gigabit Ethernet. This system generates image data of 14.4K pixel from 240 signals employing strip readout method. We have measured performance of

  12. Materials needs for compact fusion reactors

    SciTech Connect

    Krakowski, R.A.

    1983-01-01

    The economic prospects for magnetic fusion energy can be dramatically improved if for the same total power output the fusion neutron first-wall (FW) loading and the system power density can be increased by factors of 3 to 5 and 10 to 30, respectively. A number of compact fusion reactor embodiments have been proposed, all of which would operate with increased FW loadings, would use thin (0.5 to 0.6 m) blankets, and would confine quasi-steady-state plasma with resistive, water-cooled copper or aluminum coils. Increased system power density (5 to 15 MWt/m/sup 3/ versus 0.3 to 0.5 MW/m/sup 3/), considerably reduced physical size of the fusion power core (FPC), and appreciably reduced economic leverage exerted by the FPC and associated physics result. The unique materials requirements anticipated for these compact reactors are outlined against the well documented backdrop provided by similar needs for the mainline approaches. Surprisingly, no single materials need that is unique to the compact systems is identified; crucial uncertainties for the compact approaches must also be addressed by the mainline approaches, particularly for in-vacuum components (FWs, limiters, divertors, etc.).

  13. Materials needs for compact fusion reactors

    Microsoft Academic Search

    R. A. Krakowski

    1983-01-01

    The economic prospects for magnetic fusion energy is dramatically improved if for the same total power output the fusion neutron first-wall (FW) loading and the system power density is increased by factors of 3 to 5 and 10 to 30, respectively. A number of compact fusion reactor embodiments were proposed, all of which would operate with increased FW loadings, would

  14. Compact Fusion Advanced Rankine (CFARII) power cycle

    Microsoft Academic Search

    Logan

    1991-01-01

    The Compact Fusion Advanced Rankine (CFARII) power cycle is a direct plasma energy conversion scheme for inertial fusion (ICF) and magnetically-insulated, inertially confined fusion (MICF) reactors utilizing: (1) conversion of plasma thermal ionization and thermal energy into kinetic energy of a supersonic plasma jet, (2) conversion of the plasma jet kinetic energy into DC electricity by slowing down in an

  15. The obsolescent incandescent. [Compact Fluorescent Lamps

    Microsoft Academic Search

    Roodman

    2009-01-01

    The compact fluorescent light (CFL), which squeezes efficient fluorescent lighting technology into a bulb comparable to standard bulbs, has recently enjoyed a sale boom. CFL comprised less than 2% of the lamps that size sold in 1992, but 13 percent of the market in terms of lighting capacity sold. The modern CFL uses electricity to excite a tube-confined gas which

  16. Bitwise Competition Logic for Compact Digital Comparator

    E-print Network

    Yoo, Hoi-Jun

    intensive applications such as image processing and 3D graphics [3]-[4]. Therefore, a digital comparatorBitwise Competition Logic for Compact Digital Comparator Joo-Young Kim and Hoi-Jun Yoo School--In this paper, we present a Bitwise Competition Logic (BCL) for the high performance and area efficient digital

  17. ADDITIVES TO CONTROL SLAKING IN COMPACTED SHALES

    Microsoft Academic Search

    MARIAPPA SURENDRA

    1980-01-01

    Many combinations of durability and strength can be expected when dealing with shales to be used in compacted highway embankments. The classification systems used to group shales into durable and non-durable categories are based on their slaking properties and often do not consider the hardness, degradability or the physico-chemical properties. Hard and durable shales can be placed as a rock

  18. FAULT PREDICTIVE CONTROL OF COMPACT DISK PLAYERS

    E-print Network

    Wickerhauser, M. Victor

    FAULT PREDICTIVE CONTROL OF COMPACT DISK PLAYERS Peter Fogh Odgaard Mladen Victor Wickerhauser playing certain discs with surface faults like scratches and fingerprints. The problem is to be found in an other publications of the first author. This scheme is based on an assumption that the surface faults do

  19. Trust and compactness in social network groups.

    PubMed

    De Meo, Pasquale; Ferrara, Emilio; Rosaci, Domenico; Sarné, Giuseppe M L

    2015-02-01

    Understanding the dynamics behind group formation and evolution in social networks is considered an instrumental milestone to better describe how individuals gather and form communities, how they enjoy and share the platform contents, how they are driven by their preferences/tastes, and how their behaviors are influenced by peers. In this context, the notion of compactness of a social group is particularly relevant. While the literature usually refers to compactness as a measure to merely determine how much members of a group are similar among each other, we argue that the mutual trustworthiness between the members should be considered as an important factor in defining such a term. In fact, trust has profound effects on the dynamics of group formation and their evolution: individuals are more likely to join with and stay in a group if they can trust other group members. In this paper, we propose a quantitative measure of group compactness that takes into account both the similarity and the trustworthiness among users, and we present an algorithm to optimize such a measure. We provide empirical results, obtained from the real social networks EPINIONS and CIAO, that compare our notion of compactness versus the traditional notion of user similarity, clearly proving the advantages of our approach. PMID:25099965

  20. Recent developments in compact ultrafast lasers

    Microsoft Academic Search

    Ursula Keller

    2003-01-01

    Ultrafast lasers, which generate optical pulses in the picosecond and femtosecond range, have progressed over the past decade from complicated and specialized laboratory systems to compact, reliable instruments. Semiconductor lasers for optical pumping and fast optical saturable absorbers, based on either semiconductor devices or the optical nonlinear Kerr effect, have dramatically improved these lasers and opened up new frontiers for

  1. Slit extraction type compact microwave ion source

    Microsoft Academic Search

    Hiroshi Tsuji; Junzo Ishikawa; Toshinori Takagi

    1989-01-01

    A new compact microwave ion source with three antennas has been constructed; it has a large plasma production chamber (16 × 66 × 5 mm3) for increasing the extraction of ion current by a slit extraction electrode. Even in such a large plasma production chamber, the axial magnetic field (about 900 G) was formed uniformly with a combination of permanent

  2. COMPACT LOW-LEVEL COUNTING ARRANGEMENT

    Microsoft Academic Search

    K. van Duuren; W. K. Hofker; J. Hermsen

    1959-01-01

    The contribution of mesons to the background of a beta counter is ; customarily eliminated by means of a ring of anticoincidence counters. The ; application of a counter tube with hollow anode, instead of a ring of Geiger ; counters, gives the possibility of anticoincidence arrangement of much simpler ; and more compact design. A beta counter is placed

  3. Development of a highly compact steam generator

    Microsoft Academic Search

    P. A. Kew; K. Cornwell

    2005-01-01

    Conventional steam generators are the largest components in steam power plant, and add considerably to the physical size of gas turbine based combined cycle and combined heat and power plant. Availability of compact steam generators capable of operating at high pressures would make heat recovery from engine and turbine exhausts attractive in a wider range of applications. The advantages of

  4. Compact Ultradense Objects in the Solar System

    E-print Network

    J. Rafelski; Ch. Dietl; L. Labun

    2013-03-19

    We describe properties and gravitational interactions of meteor-mass and greater compact ultra dense objects with nuclear density or greater (CUDO s). We discuss possible enclosure of CUDO s in comets, stability of these objects on impact with the Earth and Sun and show that the hypothesis of a CUDO core helps resolve issues challenging the understanding of a few selected cometary impacts.

  5. Compact, Lightweight Servo-Controllable Brakes

    NASA Technical Reports Server (NTRS)

    Lovchik, Christopher S.; Townsend, William; Guertin, Jeffrey; Matsuoka, Yoky

    2010-01-01

    Compact, lightweight servo-controllable brakes capable of high torques are being developed for incorporation into robot joints. A brake of this type is based partly on the capstan effect of tension elements. In a brake of the type under development, a controllable intermediate state of torque is reached through on/off switching at a high frequency.

  6. Compact Signatures for Network Coding Jonathan Katz

    E-print Network

    Katz, Jonathan

    Compact Signatures for Network Coding Jonathan Katz Brent Waters Abstract Network coding offers of packets (i.e., "pollution attacks") by Byzantine nodes in the network; see [11, 19] for Dept. of Computer, University of Texas at Austin. bwaters@crl.sri.com. Supported by NSF CNS- 0749931, CNS-0524252, CNS-0716199

  7. Compact QED under scrutiny: it's first order

    E-print Network

    G. Arnold; B. Bunk; Th. Lippert; K. Schilling

    2002-10-07

    We report new results from our finite size scaling analysis of 4d compact pure U(1) gauge theory with Wilson action. Investigating several cumulants of the plaquette energy within the Borgs-Kotecky finite size scaling scheme we find strong evidence for a first-order phase transition and present a high precision value for the critical coupling in the thermodynamic limit.

  8. Charge capture using mobile devices.

    PubMed

    Malonis, John A

    2013-01-01

    Physicians are losing revenue every day by failing to capture the charges for all of the work that we do. In an attempt to capture charges more efficiently, my partner and I decided to incorporate a mobile charge capture solution, maxRVU, into our practice. With just three simple procedure codes, my partner and I were able to capture charges for about 350 more patients, resulting in over $100,000 more in captured charges. In this medical environment of diminishing reimbursement and increasing practice costs, physicians should capture and charge for all of the work they are doing, which can be easily done using mobile charge capture. PMID:23767126

  9. Investigation of HMA compactability using GPR technique

    NASA Astrophysics Data System (ADS)

    Plati, Christina; Georgiou, Panos; Loizos, Andreas

    2014-05-01

    In-situ field density is often regarded as one of the most important controls used to ensure that an asphalt pavement being placed is of high quality. The achieved density results from the effectiveness of the applied compaction mode on the Hot Mix Asphalt (HMA) layer. It is worthwhile mentioning that the proper compaction of HMA increases pavement fatigue life, decreases the amount of permanent deformation or rutting, reduces the amount of oxidation or aging, decreases moisture damage or stripping, increases strength and internal stability, and may decrease slightly the amount of low-temperature cracking that may occur in the mix. Conventionally, the HMA density in the field is assessed by direct destructive methods, including through the cutting of samples or drilling cores. These methods are characterized by a high accuracy, although they are intrusive and time consuming. In addition, they provide local information, i.e. information only for the exact test location. To overcome these limitations, the use of non-intrusive techniques is often recommended. The Ground Penetrating Radar (GPR) technique is an example of a non-intrusive technique that has been increasingly used for pavement investigations over the years. GPR technology is practical and application-oriented with the overall design concept, as well as the hardware, usually dependent on the target type and the material composing the target and its surroundings. As the sophistication of operating practices increases, the technology matures and GPR becomes an intelligent sensor system. The intelligent sensing deals with the expanded range of GPR applications in pavements such as determining layer thickness, detecting subsurface distresses, estimating moisture content, detecting voids and others. In addition, the practice of using GPR to predict in-situ field density of compacted asphalt mixture material is still under development and research; however the related research findings seem to be promising. Actually, the prediction is not regulated by any standards or specifications, although the practice is considered to be workable. In view of the above, an extensive experiment was carried out in both the laboratory and the field based on a trial asphalt pavement section under construction. In the laboratory, the study focused on the estimation of the density of HMA specimens achieved through three different roller compaction modes (static, vibratory and a combination of both) targeted to simulate field compaction and assess the asphalt mix compactability. In the field, the different compaction modes were successively implemented on three subsections of the trial pavement section. Along each subsection, GPR data was collected in order to determine the new material's dielectric properties and based on that, to predict its density using proper algorithm. Thus, cores were extracted to be used as ground truth data. The comparison of the new asphalt material compactability as obtained from the laboratory specimens, the predictions based on GPR data and the field cores provided useful information that facilitated the selection of the most effective compaction mode yielding the proper compaction degree in the field. This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

  10. Monopole-charge instability

    E-print Network

    Horváthy, P A; Rawnsley, J H

    2009-01-01

    For monopoles with nonvanishing Higgs potential it is shown that with respect to "Brand-Neri-Coleman type" variations (a) the stability problem reduces to that of a pure gauge theory on the two-sphere (b) each topological sector admits one, and only one, stable monopole charge, and (c) each unstable monopole admits $2\\sum_{q<0} (2|q|-1)$ negative modes, where the sum goes over all negative eigenvalues $q$ of the non-Abelian charge $Q$. An explicit construction for (i) the unique stable charge (ii) the negative modes and (iii) the spectrum of the Hessian, on the 2-sphere, is then given. The relation to loops in the residual group is explained. The negative modes are tangent to suitable energy-reducing two-spheres. The general theory is illustrated for the little groups U(2), U(3), SU(3)/Z_3 and O(5).

  11. Dispersion and space charge

    SciTech Connect

    Venturini, Marco [Department of Physics and Institute for Plasma Research, University of Maryland, College Park, Maryland 20742 (United States); Kishek, Rami A.; Reiser, Martin [Department of Electrical Engeneering and Institute for Plasma Research, University of Maryland, College Park, Maryland 20742 (United States)

    1998-11-05

    The presence of space charge affects the value of the dispersion function. On the other hand dispersion has a role in shaping the beam distribution and therefore in determining the resulting forces due to space charge. In this paper we present a framework where the interplay between space charge and dispersion for a continuous beam can be simultaneously treated. We revise the derivation of a new set of rms envelope-dispersion equations we have recently proposed. The new equations generalize the standard rms envelope equations currently used for matching to the case where bends and a longitudinal momentum spread are present. We report a comparison between the solutions of the rms envelope-dispersion equations and the results obtained using WARP, a Particle in Cell (PIC) code, in the modeling of the Maryland Electron Ring.

  12. Charge gradient microscopy.

    PubMed

    Hong, Seungbum; Tong, Sheng; Park, Woon Ik; Hiranaga, Yoshiomi; Cho, Yasuo; Roelofs, Andreas

    2014-05-01

    Here we present a simple and fast method to reliably image polarization charges using charge gradient microscopy (CGM). We collected the current from the grounded CGM probe while scanning a periodically poled lithium niobate single crystal and single-crystal LiTaO3 thin film on the Cr electrode. We observed current signals at the domains and domain walls originating from the displacement current and the relocation or removal of surface charges, which enabled us to visualize the ferroelectric domains at a scan frequency above 78 Hz over 10 ?m. We envision that CGM can be used in high-speed ferroelectric domain imaging and piezoelectric energy-harvesting devices. PMID:24760831

  13. A polytropic model for the solar wind

    Microsoft Academic Search

    C. Jacobs; S. Poedts

    2011-01-01

    The solar wind fills the heliosphere and is the background medium in which coronal mass ejections propagate. A realistic modelling of the solar wind is therefore essential for space weather research and for reliable predictions. Although the solar wind is highly anisotropic, magnetohydrodynamic (MHD) models are able to reproduce the global, average solar wind characteristics rather well. The modern computer

  14. The Dynamic Compact Control Language: A compact marshalling scheme for acoustic communications

    E-print Network

    Schneider, Toby Edwin

    The Dynamic Compact Control Language (DCCL) extends the ubiquitous Extensible Markup Language (XML) to provide a structure for defining very short messages comprised of bounded basic variable types, suitable for transmission ...

  15. Quick charge battery

    SciTech Connect

    Parise, R.J.

    1998-07-01

    Electric and hybrid electric vehicles (EVs and HEVs) will become a significant reality in the near future of the automotive industry. Both types of vehicles will need a means to store energy on board. For the present, the method of choice would be lead-acid batteries, with the HEV having auxiliary power supplied by a small internal combustion engine. One of the main drawbacks to lead-acid batteries is internal heat generation as a natural consequence of the charging process as well as resistance losses. This limits the re-charging rate to the battery pack for an EV which has a range of about 80 miles. A quick turnaround on recharge is needed but not yet possible. One of the limiting factors is the heat buildup. For the HEV the auxiliary power unit provides a continuous charge to the battery pack. Therefore heat generation in the lead-acid battery is a constant problem that must be addressed. Presented here is a battery that is capable of quick charging, the Quick Charge Battery with Thermal Management. This is an electrochemical battery, typically a lead-acid battery, without the inherent thermal management problems that have been present in the past. The battery can be used in an all-electric vehicle, a hybrid-electric vehicle or an internal combustion engine vehicle, as well as in other applications that utilize secondary batteries. This is not restricted to only lead-acid batteries. The concept and technology are flexible enough to use in any secondary battery application where thermal management of the battery must be addressed, especially during charging. Any battery with temperature constraints can benefit from this advancement in the state of the art of battery manufacturing. This can also include nickel-cadmium, metal-air, nickel hydroxide, zinc-chloride or any other type of battery whose performance is affected by the temperature control of the interior as well as the exterior of the battery.

  16. Charged Conformal Killing Spinors

    E-print Network

    Andree Lischewski

    2014-08-10

    We study the twistor equation on pseudo-Riemannian $Spin^c-$manifolds whose solutions we call charged conformal Killing spinors (CCKS). We derive several integrability conditions for the existence of CCKS and study their relations to spinor bilinears. A construction principle for Lorentzian manifolds admitting CCKS with nontrivial charge starting from CR-geometry is presented. We obtain a partial classification result in the Lorentzian case under the additional assumption that the associated Dirac current is normal conformal and complete the Classification of manifolds admitting CCKS in all dimensions and signatures $\\leq 5$ which has recently been initiated in the study of supersymmetric field theories on curved space.

  17. HIV charge dropped.

    PubMed

    1997-07-25

    Guilford County Superior Court Judge James Webb ruled there was not enough evidence to convict HIV-positive [name removed] on charges of attempted murder and assault with a deadly weapon in connection with the rape of a 12-year-old girl. Prosecutors argued [name removed] knew he was HIV-positive when the rape occurred and defense attorney Randy Jones argued that there was no medical proof of [name removed]'s HIV status at the time of the attack. The judge dismissed the two charges against [name removed]. A jury later convicted [name removed] of statutory rape and taking indecent liberties with a minor. PMID:11364510

  18. Charged Particle in Capacitor

    NSDL National Science Digital Library

    In this interactive simulation, the path of a charged particle in a capacitor can be traced. Users may adjust the strength of field, initial velocity and mass of the moving particle, and magnitude of its charge. The simulated path can be viewed in continuous or step mode, with or without a vector display of the position, velocity, acceleration, or force. Also available for display are bar graphs depicting kinetic and potential energy. This item is part of a larger collection of physics simulations sponsored by the MAP project (Modular Approach to Physics).

  19. Holographic charge oscillations

    NASA Astrophysics Data System (ADS)

    Blake, Mike; Donos, Aristomenis; Tong, David

    2015-04-01

    The Reissner-Nordström black hole provides the prototypical description of a holographic system at finite density. We study the response of this system to the presence of a local, charged impurity. Below a critical temperature, the induced charge density, which screens the impurity, exhibits oscillations. These oscillations can be traced to the singularities in the density-density correlation function moving in the complex momentum plane. At finite temperature, the oscillations are very similar to the Friedel oscillations seen in Fermi liquids. However, at zero temperature the oscillations in the black hole background remain exponentially damped, while Friedel oscillations relax to a power-law.

  20. Mineral surface charge development in mixed electrolyte solutions.

    PubMed

    Kozin, Philipp A; Boily, Jean-François

    2014-03-15

    Effects of competing counterions with different charge-to-size ratios on potential-determining ion (pdi; H(+), OH(-)) adsorption at mineral/water interfaces were resolved in mixtures of aqueous solutions of NaCl and NaClO4 solutions. These effects were monitored on two synthetic goethite (?-FeOOH) particle preparations with distinct charge uptake capacities arising from differences in surface roughness. Charge development at these mineral surfaces was chiefly explored by high precision potentiometric titrations at 25 °C. These measurements confirmed that the greater charge-to-size ratio chloride ion not only promoted greater surface charge, but also had pronounced effects in perchlorate-dominated solutions. Cryogenic X-ray photoelectron spectroscopic measurements confirmed that perchlorate retains significant loadings at the goethite surface, even in the presence of chloride. Molecular dynamics simulations of the (110) plane of goethite exposed to these mixed solutions showed that chloride compressed the interfacial region containing electrolyte ions. Perchlorate, on the other hand, is not only present over a thicker region of the interface but also promotes an additional outer-sphere sodium species. These findings were used to develop a thermodynamic adsorption model predicting charge development at these mineral surfaces. The model involves a new formulation accounting for coexisting ion-specific regions each with their distinct compact plane capacitance values. The model can predict charge development in any mixtures of NaCl and NaClO4 contacted with goethite particles of contrasting charge uptake capacities without any additional parameters. This model can also be applied to a broader range of material surfaces. PMID:24461842

  1. Fundamental building blocks for a compact optoelectronic neural network processor

    E-print Network

    Ruedlinger, Benjamin Franklin, 1976-

    2003-01-01

    The focus of this thesis is interconnects within the Compact Optoelectronic Neural Network Processor. The goal of the Compact Optoelectronic Neural Network Processor Project (CONNPP) is to build a small, rugged neural ...

  2. Fixed point theory for compact absorbing contractive admissible type maps

    Microsoft Academic Search

    Ravi P. Agarwal; Donal ORegan

    2008-01-01

    In this article we present new Lefschetz fixed point theorems for compact absorbing contractive admissible maps between Fréchet spaces. Also, we discuss condensing maps with a compact attractor. Finally we present new antipodal fixed point theory for Kakutani maps.

  3. A study of compaction methods for lunar soil simulants

    E-print Network

    Ekkad, Rama Varadarajan

    1993-01-01

    , compaction by vibration, compaction under vacuum pressure under the simultaneous effect of vibration are examined. Duc to the increasing confining pressure, the air voids decrease and the particles will be more closely packed, thus increasing the relative... density. The research will be used to identify a convenient method for compacting samples for laboratory digging experiments. The results of the research conclude that compaction by using vacuum and vibration produce results which can be used to predict...

  4. Effect of die wall lubrication on warm compaction powder metallurgy

    Microsoft Academic Search

    Y. Y Li; T. L Ngai; D. T Zhang; Y Long; W Xia

    2002-01-01

    Die wall lubrication was applied on warm compaction powder metallurgy in the hope to reduce the concentration level of the admixed lubricant, since lubricant is harmful to the mechanical properties of the sintered material. Iron-based samples were prepared by die wall lubricated warm compaction at 135 and 175°C, using polytetrafluoroethylene (PTFE) emulsion as the die wall lubricant. Compacting pressures of

  5. Approximating Radon measures on first--countable compact spaces

    E-print Network

    Plebanek, Grzegorz

    Approximating Radon measures on first--countable compact spaces Grzegorz Plebanek (Wroc/law) Abstract The assertion every Radon measure defined on a first--countable compact space is uniformly regular under CH. In this note we consider some properties of finite Radon measures defined on compact spaces

  6. Self-Compacting Concrete - Procedure for Mix Design

    Microsoft Academic Search

    Paratibha AGGARWAL; Rafat SIDDIQUE; Yogesh AGGARWAL; Surinder M GUPTA

    Self-compacting concrete is a fluid mixture suitable for placing in structures with congested reinforcement without vibration. Self-compacting concrete development must ensure a good balance between deformability and stability. Also, compactibility is affected by the characteristics of materials and the mix proportions; it becomes necessary to evolve a procedure for mix design of SCC. The paper presents an experimental procedure for

  7. CRIGOS: a compact robot for image-guided orthopedic surgery

    Microsoft Academic Search

    Guido Brandt; Andreas Zimolong; Lionel Carrat; Philippe Merloz; Hans-Walter Staudte; Stéphane Lavallée; Klaus Radermacher; Günther Rau

    1999-01-01

    The CRIGOS (compact robot for image-guided orthopedic surgery) project was set up for the development of a compact surgical robot system for image-guided orthopedic surgery based on user requirements. The modular system comprises a compact parallel robot and a software system for planning of surgical interventions and for supervision of the robotic device. Because it is not sufficient to consider

  8. Path to Market for Compact Modular Fusion Power Cores

    E-print Network

    Path to Market for Compact Modular Fusion Power Cores S. Woodruff, J. K. Baerny, N. Mattor, J. E distant' Solution: making fusion systems compact and modular opens path to market #12;12/13/11 3 Outline fusion systems compact and modular opens path to market #12;12/13/11 4 CT Lead CT Lead ICC special

  9. Compact anechoic chamber for immunity test and EMI noise measurement

    Microsoft Academic Search

    K. Ishino; Y. Hashimoto; M. Okamura; Y. Shimizu

    1991-01-01

    The distribution of the electromagnetic field in the compact anechoic chamber consisting of four walls, ceiling, and floor with ferrite absorbing materials was investigated. The compact anechoic chamber used for both immunity test and electromagnetic interference (EMI) noise measurement was developed by improved ferrite absorber. The compact chamber was extremely uniform, and the maximum deviation is less than 6 dB

  10. Agronomic consequences of tractor wheel compaction on a clay soil

    Microsoft Academic Search

    K. Y. Chan; A. Oates; A. D. Swan; R. C. Hayes; B. S. Dear; M. B. Peoples

    2006-01-01

    In southern New South Wales, Australia, farming operations using tractors often occur when the soils are moist and prone to soil compaction. However, the extent of soil compaction and its relative impact on crop yield have not been quantified in the region. In this experiment, re-compaction due to tractor wheel traffic in a sodic brown clay (Vertisol) was monitored under

  11. Agronomic consequences of tractor wheel compaction on a clay soil

    Microsoft Academic Search

    K. Y. Chan; A. Oates; A. D. Swan; R. C. Hayes; B. S. Dear; M. B. Peoples

    2005-01-01

    In southern New South Wales, Australia, farming operations using tractors often occur when the soils are moist and prone to soil compaction. However, the extent of soil compaction and its relative impact on crop yield have not been quantified in the region. In this experiment, re-compaction due to tractor wheel traffic in a sodic brown clay (Vertisol) was monitored under

  12. A COMPACT ASIC IMPLEMENTATION OF THE ADVANCED ENCRYPTION STANDARD

    E-print Network

    Heys, Howard

    A COMPACT ASIC IMPLEMENTATION OF THE ADVANCED ENCRYPTION STANDARD WITH CONCURRENT ERROR DETECTION the application of concurrent error detection circuitry to a compact application-specific integrated circuit (ASIC a method suitable for compact ASIC implementations targeted to embedded systems such that the system

  13. Charge separation in liquids

    NASA Astrophysics Data System (ADS)

    Mikhelashvili, M. S.; Agam, O.

    2004-10-01

    The common theory of reversible charge transfer (RCT) at low donor system excitation power in liquids is examined. The space averaging procedures describing the kinetics of RCT in the liquid space are discussed. The reaction space is presented as a totality of independent subgroups with one excited donor and some group of acceptors effectively interacting only with the donor in the given “subgroup”. We have shown that the theory [3-5] gives questionable results for cation state probability for the usual parameters of this problem. If the acceptor concentration or the charge transfer rate constants are low, then the cation state probability behaves the same in the two theories [3-5] and [7, 8]. The correct account of the donor’s ground state change and charge back transfer in the RCT theory gives the new, not contradictory results, different from the behavior of the results in references [3-5], but near to results of [7, 8]. The molecules motion accelerates the ionization of donors and neutralization of ions. The influence of the motion of neutral and ionized molecules on charge transfer kinetics is different. The Coulomb interaction of ions is taken into account; the effect depends on the space averaging method used. The new approximation in this article in comparison with references [3-6,9] consists in the space averaging procedure of the donor cation state probability, which takes into account the donor’s ground state.

  14. Duct type charge eliminator

    SciTech Connect

    Masuda, S.

    1984-09-18

    At least one planar type plasma ion source is positioned in a main duct through which charged materials pass in a manner whereby its active surface producing plasma faces the flow channel of charged materials inside the duct. The plasma ion source has at least one dielectric sheet, at least one corona electrode in operative proximity with one surface of the dielectric sheet and at least one planar type exciting electrode affixed to the opposite surface of the dielectric sheet and covering the entire area facing the corona electrode. A high voltage AC power supply energizes the plasma ion source by producing a high AC voltage and being connected to apply the voltage between the corona and the exciting electrode across the dielectric sheet whereby AC surface coronas serving as an active planar type plasma containing copious positive and negative ions are produced by the corona electrode along the one surface of the dielectric sheet and charged materials entering the flow channel inside the duct are bombarded by ions of opposite polarity from the plasma and are rapidly neutralized in charge during passage through the flow channel.

  15. Who's in Charge Here?

    ERIC Educational Resources Information Center

    Humphries, Jack W.

    1986-01-01

    Even though most decisions are made before they reach the superintendent's desk, and even though these are times of "litigious paranoia," the superintendent is still in charge of the public schools. Some of the responsibilities of the superintendent are outlined. (MLW)

  16. Dissolution and compaction instabilities in geomaterials

    NASA Astrophysics Data System (ADS)

    Stefanou, I.; Sulem, J.; de Sauvage, J.

    2014-12-01

    Compaction bands play an important role in reservoir engineering and geological storage. Their presence in geological formations may also provide useful information on various geological processes. Several mechanisms can be involved at different scales and may be responsible for compaction band instabilities [1]. Compaction bands can be seen as a particular instability of the governing mathematical system leading to localization of deformation [2-4]. In a saturated porous rock, the progressive mechanical damage of the solid skeleton during compaction, results in the increase of the interface area of the reactants and consequently in the acceleration of the dissolution rate of the solid phase [2,5]. Thus, the solid skeleton is degraded more rapidly (mass removal because of dissolution), the overall mechanical properties of the system diminish (contraction of the elastic domain - chemical softening), deformations increase and the solid skeleton is further damaged (intergranular fractures, debonding, breakage of the porous network etc.). The stability of this positive feedback process is investigated analytically through linear stability analysis by considering the strong chemo-poro-mechanical coupling due to chemical dissolution. The post bifurcation behavior is then studied analytically and numerically revealing the compaction band thickness and periodicity. The effect of various parameters is studied as for instance the influence of the hydraulic diffusivity on the compaction band thickness. [1] P. Baud, S. Vinciguerra, C. David, A. Cavallo, E. Walker and T. Reuschlé (2009), Pure Appl. Geophys., 166(5-7), 869-898 [2] I. Stefanou and J. Sulem (2014), JGR: Solid Earth, 119(2), 880-899. doi:10.1002/2013JB010342I [3] J.W. Rudnicki and J.R. Rice (1975), Journal of the Mechanics and Physics of Solids 23(6),: 371-394 [4] K.A. Issen and J.W. Rudnicki (2000), JGR, 105(B9), 21529. doi:10.1029/2000JB900185 [5] R. Nova, R. Castellanza and C. Tamagnini (2003), International Journal for Numerical and Analytical Methods in Geomechanics, 27(9): 705-732

  17. Operating single quantum emitters with a compact Stirling cryocooler

    NASA Astrophysics Data System (ADS)

    Schlehahn, A.; Krüger, L.; Gschrey, M.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T.; Reitzenstein, S.

    2015-01-01

    The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g(2)(0) < 0.04 from this Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g(2)(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources.

  18. An Innovative Magnetic Charging Chute to Improve Productivity of Sinter Machine at Rourkela Steel Plant

    NASA Astrophysics Data System (ADS)

    Selvam, Sambandham Thirumalai; Chaudhuri, Subhasis; Das, Arunaba; Singh, Mithilesh Kumar; Mahanta, H. K.

    Sintering is a process in sinter machine for agglomeration of iron ore and other raw material fines into a compact porous mass, i.e., sinter, used in Blast Furnaces as an iron bearing input charge material for hot metal production. 'Permeability' of sinter-bed on sinter machine i.e., the porosity in sinter-bed of charged materials, facilitates atmospheric air passes from the top to bottom across the depth of sinter-bed, when suction created from the bottom of the bed, for efficient heat carry over from top to bottom of the bed for complete burning of charged materials for effective sintering process controls the productivity of the sinter machine. The level of 'permeability' in sinter-bed is depending upon the effectiveness of 'charging chute' in size-wise 'segregation' of charge materials across the depth in sinter-bed, achieved due to differences in the sliding velocities of particles during charging into the moving sinter-bed. The permeability achieved by the earlier conventional 'charging chute' was limited due to its design and positional constraints in sinter machine. Improving the productivity of sinter machine, through increased permeability of sinter bed is successfully achieved through implementation of an innovatively designed and developed, "Magnetic Charging Chute" at Sinter Plant no. 2 of Rourkela Steel Plant. The induced magnetic force on the charged materials while the charge materials dropping down through the charge chute has improved the permeability of sinter bed through an unique method of segregating the para-magnetic materials and the finer materials of the charge materials to top layer of sinter bed along with improved size-wise segregation of charge materials. This has increased the productivity of the sinter machine by 3% and also reduced the solid fuel consumption i.e., coke breeze in input charge materials by 1 kg/t of sinter.

  19. Monochromatic short pulse laser produced ion beam using a compact passive magnetic device

    SciTech Connect

    Chen, S. N.; Gauthier, M.; Higginson, D. P.; Dorard, S.; Marquès, J.-R.; Fuchs, J. [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France)] [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Mangia, F.; Atzeni, S. [Dipartimento SBAI, Università di Roma “La Sapienza,” Roma (Italy)] [Dipartimento SBAI, Università di Roma “La Sapienza,” Roma (Italy); Riquier, R. [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France) [LULI, École Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-04-15

    High-intensity laser accelerated protons and ions are emerging sources with complementary characteristics to those of conventional sources, namely high charge, high current, and short bunch duration, and therefore can be useful for dedicated applications. However, these beams exhibit a broadband energy spectrum when, for some experiments, monoenergetic beams are required. We present here an adaptation of conventional chicane devices in a compact form (10 cm × 20 cm) which enables selection of a specific energy interval from the broadband spectrum. This is achieved by employing magnetic fields to bend the trajectory of the laser produced proton beam through two slits in order to select the minimum and maximum beam energy. The device enables a production of a high current, short duration source with a reproducible output spectrum from short pulse laser produced charged particle beams.

  20. Symmetrical unified compact model of short-channel double-gate MOSFETs

    NASA Astrophysics Data System (ADS)

    Papathanasiou, K.; Theodorou, C. G.; Tsormpatzoglou, A.; Tassis, D. H.; Dimitriadis, C. A.; Bucher, M.; Ghibaudo, G.

    2012-03-01

    An explicit charge-based unified compact drain current model for lightly doped or undoped DG MOSFETs is proposed. It takes into account the short-channel effects, the subthreshold slope degradation, the drain-induced barrier lowering and the channel length modulation effects. The model is valid and continuous in all regimes of operation and it has been validated by developing a Verilog-A code and comparing the model results of transfer and output characteristics with simulation results exhibiting an average error of about 3%. The efficient solution of the Lambert W function for the inversion charge and the symmetry of the model make it suitable for circuit simulation and allow fast and accurate simulations of the transistor characteristics.

  1. Observation of vacuum-ultraviolet Kr(2)* laser oscillation pumped by a compact discharge device.

    PubMed

    Sasaki, W; Shirai, T; Kubodera, S; Kawanaka, J; Igarashi, T

    2001-04-15

    We have demonstrated vacuum-ultraviolet (VUV) Kr(2) * laser oscillation as a result of the realization of a stable self-sustained discharge of high-pressure Kr by use of a compact discharge device. Glow discharge was obtained with as much as 10 atm of pure Kr. The VUV emission intensity centered at 147.8 nm abruptly increased when the charging voltage exceeded a certain value. In addition to this threshold behavior, considerable spectral narrowing (4.0?0.4 nm) was observed when the charging voltage increased. The maximum output energy at 148 nm was 150muJ . The gain coefficient was estimated to be 1.1% cm (-1) . PMID:18040366

  2. Tribo-electric charging and adhesion of cellulose ethers and their mixtures with flurbiprofen.

    PubMed

    Ghori, Muhammad U; Supuk, Enes; Conway, Barbara R

    2014-12-18

    The pervasiveness of tribo-electric charge during pharmaceutical processing can lead to the exacerbation of a range of problems including segregation, content heterogeneity and particle surface adhesion. The excipients, hydroxypropyl methylcellulose (HPMC) and methylcellulose (MC), are often used in drug delivery systems and so it is important to understand the impact of associated factors on their charging and adhesion mechanisms, however, little work has been reported in this area. Such phenomena become more prominent when excipients are introduced to a powder mixture alongside the active pharmaceutical ingredient(s) (APIs) with inter- and intra-particulate interactions giving rise to electrification and surface adhesion of powder particles. The aim of this study was to understand the impact of material attributes (particle size, hydroxypropyl (Hpo) to methoxyl (Meo) ratio and molecular size) on the charging and adhesion characteristics of cellulose ethers. Furthermore, a poorly compactible and highly electrostatically charged drug, flurbiprofen, was used to develop binary powder mixtures having different polymer to drug ratios and the relationship between tribo-electric charging and surface adhesion was studied. Charge was induced on powder particles and measured using a custom built device based on a shaking concept, consisting of a Faraday cup connected to an electrometer. The diversity in physicochemical properties has shown a significant impact on the tribo-electric charging and adhesion behaviour of MC and HPMC. Moreover, the adhesion and electrostatic charge of the API was significantly reduced when MC and HPMC were incorporated and tribo-electric charging showed a linear relationship (R(2)=0.81-0.98) with particle surface adhesion, however, other factors were also involved. It is anticipated that such a reduction in charge and particle surface adhesion would improve flow and compaction properties during processing. PMID:25193137

  3. Gated charged-particle trap

    DOEpatents

    Benner, W. Henry (Danville, CA)

    1999-01-01

    The design and operation of a new type of charged-particle trap provides simultaneous measurements of mass, charge, and velocity of large electrospray ions. The trap consists of a detector tube mounted between two sets of center-bored trapping plates. Voltages applied to the trapping plates define symmetrically-opposing potential valleys which guide axially-injected ions to cycle back and forth through the charge-detection tube. A low noise charge-sensitive amplifier, connected to the tube, reproduces the image charge of individual ions as they pass through the detector tube. Ion mass is calculated from measurement of ion charge and velocity following each passage through the detector.

  4. Compact stars with color superconducting quark matter

    E-print Network

    Mark Alford; Sanjay Reddy

    2002-12-11

    We study compact stars that contain quark matter. We look at the effect of color superconductivity in the quark matter on the nuclear-quark matter transition density, mass-radius relationship, and the density discontinuity at the boundary between nuclear and quark matter. We find that color superconducting quark matter will occur in compact stars at values of the bag constant where ordinary quark matter would not be allowed. We are able to construct ``hybrid'' stars with a color superconducting quark matter interior and nuclear matter surface, with masses in the range 1.3-1.6 M_solar and radii 8-11 km. Our results are consistent with recent mass-radius limits based on absorption lines from EXO0748-676.

  5. Compact Structure in FIRST Survey Sources

    E-print Network

    Porcas, R W; Ghosh, T; Salter, C J; Garrington, S T

    2004-01-01

    We present preliminary results from a statistical survey of compact structure in faint radio sources. Around 1000 sources from the VLA FIRST survey (flux densities larger than 1 mJy at 1.4 GHz) have been observed with the single-baseline interferometer Effelsberg-Arecibo. We observed each source, selected from a narrow strip of sky at declination 28 deg, for just one minute. The baseline sensitivity at 1.4 GHz, using 512 Mb/s recording, is such that any FIRST source, selected at random, would be detected if most of its flux density is in compact structure. We discuss the detection-rate statistics from one epoch of these observations.

  6. Compact Structure in FIRST Survey Sources

    E-print Network

    R. W. Porcas; W. Alef; T. Ghosh; C. J. Salter; S. T. Garrington

    2004-12-29

    We present preliminary results from a statistical survey of compact structure in faint radio sources. Around 1000 sources from the VLA FIRST survey (flux densities larger than 1 mJy at 1.4 GHz) have been observed with the single-baseline interferometer Effelsberg-Arecibo. We observed each source, selected from a narrow strip of sky at declination 28 deg, for just one minute. The baseline sensitivity at 1.4 GHz, using 512 Mb/s recording, is such that any FIRST source, selected at random, would be detected if most of its flux density is in compact structure. We discuss the detection-rate statistics from one epoch of these observations.

  7. Compact de-NOxer for automotive exhaust

    SciTech Connect

    Chang, B.; Garcia, M.

    1996-06-01

    Our two year project concluded with mixed results. The basic idea of using ozone and hydroxyl radical in a two stage plasma chemical reactor to remove NO{sub x} from automotive exhaust proved to be correct. However we found the energy needed to operate the plasma chemical reactor is 30% of the engine`s output, which is three times larger than that of the conventional catalytic converter. Our project is a partial success. If compactness is dropped as a requirement for our plasma-chemical reactor so that it is applicable to stationary rather than mobile power generators, then the reactor needs only 5% of the engine`s power. The energy inefficient component of the reactor, the part which makes our reactor compact, would be unnecessary. Thus our reactor has the potential for being a practical device to remove the NO{sub x} from the emissions of power plants.

  8. Possibility of higher dimensional anisotropic compact star

    E-print Network

    Bhar, Piyali; Ray, Saibal; Chatterjee, Vikram

    2015-01-01

    We have provided here a new class of interior solutions for anisotropic stars admitting conformal motion in higher dimensional noncommutative spacetime. The Einstein fields equations are solved by choosing a particular density distribution function of Lorentzian type \\cite{Nozari} under noncommutative geometry. Several cases with dimensions $4D$ and higher, e.g. $5D$, $6D$ and $11D$ have been discussed separately. An overall observation is that the model parameters, such as density, radial pressure, transverse pressure, anisotropy all are well behaved and represent a compact star with radius $4.17$ km. However, emphasis has been given on the acceptability of the model from physical point of view. As a consequence it is observed that higher dimensions, i.e. beyond $4D$ spacetime, exhibit several interesting yet bizarre features which are not at all untenable for a compact stellar model of strange quark type and thus dictates a possibility of its extra dimensional existence.

  9. Possibility of higher dimensional anisotropic compact star

    E-print Network

    Piyali Bhar; Farook Rahaman; Saibal Ray; Vikram Chatterjee

    2015-05-14

    We have provided here a new class of interior solutions for anisotropic stars admitting conformal motion in higher dimensional noncommutative spacetime. The Einstein fields equations are solved by choosing a particular density distribution function of Lorentzian type \\cite{Nozari} under noncommutative geometry. Several cases with dimensions $4D$ and higher, e.g. $5D$, $6D$ and $11D$ have been discussed separately. An overall observation is that the model parameters, such as density, radial pressure, transverse pressure, anisotropy all are well behaved and represent a compact star with radius $4.17$ km. However, emphasis has been given on the acceptability of the model from physical point of view. As a consequence it is observed that higher dimensions, i.e. beyond $4D$ spacetime, exhibit several interesting yet bizarre features which are not at all untenable for a compact stellar model of strange quark type and thus dictates a possibility of its extra dimensional existence.

  10. Compact inductive energy storage pulse power system

    NASA Astrophysics Data System (ADS)

    K, Senthil; Mitra, S.; Roy, Amitava; Sharma, Archana; Chakravarthy, D. P.

    2012-05-01

    An inductive energy storage pulse power system is being developed in BARC, India. Simple, compact, and robust opening switches, capable of generating hundreds of kV, are key elements in the development of inductive energy storage pulsed power sources. It employs an inductive energy storage and opening switch power conditioning techniques with high energy density capacitors as the primary energy store. The energy stored in the capacitor bank is transferred to an air cored storage inductor in 5.5 ?s through wire fuses. By optimizing the exploding wire parameters, a compact, robust, high voltage pulse power system, capable of generating reproducibly 240 kV, is developed. This paper presents the full details of the system along with the experimental data.

  11. A compact PE memory for vision chips

    NASA Astrophysics Data System (ADS)

    Cong, Shi; Zhe, Chen; Jie, Yang; Nanjian, Wu; Zhihua, Wang

    2014-09-01

    This paper presents a novel compact memory in the processing element (PE) for single-instruction multiple-data (SIMD) vision chips. The PE memory is constructed with 8 × 8 register cells, where one latch in the slave stage is shared by eight latches in the master stage. The memory supports simultaneous read and write on the same address in one clock cycle. Its compact area of 14.33 ?m2/bit promises a higher integration level of the processor. A prototype chip with a 64 × 64 PE array is fabricated in a UMC 0.18 ?m CMOS technology. Five types of the PE memory cell structure are designed and compared. The testing results demonstrate that the proposed PE memory architecture well satisfies the requirement of the vision chip in high-speed real-time vision applications, such as 1000 fps edge extraction.

  12. A compact high field magnetic force microscope.

    PubMed

    Zhou, Haibiao; Wang, Ze; Hou, Yubin; Lu, Qingyou

    2014-12-01

    We present the design and performance of a simple and compact magnetic force microscope (MFM), whose tip-sample coarse approach is implemented by the piezoelectric tube scanner (PTS) itself. In brief, a square rod shaft is axially spring-clamped on the inner wall of a metal tube which is glued inside the free end of the PTS. The shaft can thus be driven by the PTS to realize image scan and inertial stepping coarse approach. To enhance the inertial force, each of the four outer electrodes of the PTS is driven by an independent port of the controller. The MFM scan head is so compact that it can easily fit into the 52mm low temperature bore of a 20T superconducting magnet. The performance of the MFM is demonstrated by imaging a manganite thin film at low temperature and in magnetic fields up to 15T. PMID:25189114

  13. Spinning compact binary dynamics and chameleon orbits

    E-print Network

    László Árpád Gergely; Zoltán Keresztes

    2014-12-20

    We analyse the conservative evolution of spinning compact binaries to second post-Newtonian (2PN) order accuracy, with leading order spin-orbit, spin-spin and mass quadrupole-monopole contributions included. As a main result we derive a closed system of first order differential equations in a compact form, for a set of dimensionless variables encompassing both orbital elements and spin angles. These evolutions are constrained by conservation laws holding at 2PN order. As required by the generic theory of constrained dynamical systems we perform a consistency check and prove that the constraints are preserved by the evolution. We apply the formalism to show the existence of chameleon orbits, whose local, orbital parameters evolve from elliptic (in the Newtonian sense) near pericenter, towards hyperbolic at large distances. This behavior is consistent with the picture that General Relativity predicts stronger gravity at short distances than Newtonian theory does.

  14. Compact dusty clouds in a cosmic environment

    SciTech Connect

    Tsytovich, V. N. [General Physics Institute, Russian Academy of Sciences, 117942 Moscow (Russian Federation); Ivlev, A. V.; Burkert, A.; Morfill, G. E., E-mail: ivlev@mpe.mpg.de [Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany)

    2014-01-10

    A novel mechanism of the formation of compact dusty clouds in astrophysical environments is discussed. It is shown that the balance of collective forces operating in space dusty plasmas can result in the effect of dust self-confinement, generating equilibrium spherical clusters. The distribution of dust and plasma density inside such objects and their stability are investigated. Spherical dusty clouds can be formed in a broad range of plasma parameters, suggesting that this process of dust self-organization might be a generic phenomenon occurring in different astrophysical media. We argue that compact dusty clouds can represent condensation seeds for a population of small-scale, cold, gaseous clumps in the diffuse interstellar medium. They could play an important role in regulating its small-scale structure and its thermodynamical evolution.

  15. Compaction of granular material inside confined geometries

    E-print Network

    Benjy Marks; Bjørnar Sandnes; Guillaume Dumazer; Jon Alm Eriksen; Knut Jørgen Måløy

    2015-05-15

    In both nature and engineering, loosely packed granular materials are often compacted inside confined geometries. Here, we explore such behaviour in a quasi-two dimensional geometry, where parallel rigid walls provide the confinement. We use the discrete element method to investigate the stress distribution developed within the granular packing as a result of compaction due to the displacement of a rigid piston. We observe that the stress within the packing increases exponentially with the length of accumulated grains, and show an extension to current analytic models which fits the measured stress. The micromechanical behaviour is studied for a range of system parameters, and the limitations of existing analytic models are described. In particular, we show the smallest sized systems which can be treated using existing models. Additionally, the effects of increasing piston rate, and variations of the initial packing fraction, are described.

  16. Tidal deformations of a spinning compact object

    E-print Network

    Pani, Paolo; Maselli, Andrea; Ferrari, Valeria

    2015-01-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole mom...

  17. Approximation functions for airblast environments from buried charges

    SciTech Connect

    Reichenbach, H.; Behrens, K. [Fraunhofer-Institut fuer Kurzzeitdynamik - Ernst-Mach-Institut (EMI), Freiburg im Breisgau (Germany); Kuhl, A.L. [Lawrence Livermore National Lab., El Segundo, CA (United States)

    1993-11-01

    In EMI report E 1/93, ``Airblast Environments from Buried HE-Charges,`` fit functions were used for the compact description of blastwave parameters. The coefficients of these functions were approximated by means of second order polynomials versus DOB. In most cases, the agreement with the measured data was satisfactory; to reduce remaining noticeable deviations, an approximation by polygons (i.e., piecewise-linear approximation) was used instead of polynomials. The present report describes the results of the polygon approximation and compares them to previous data. We conclude that the polygon representation leads to a better agreement with the measured data.

  18. Transverse-structure electrostatic charged particle beam lens

    DOEpatents

    Moran, Michael J. (Pleasanton, CA)

    1998-01-01

    Electrostatic particle-beam lenses using a concentric co-planar array of independently biased rings can be advantageous for some applications. Traditional electrostatic lenses often consist of axial series of biased rings, apertures, or tubes. The science of lens design has devoted much attention to finding axial arrangements that compensate for the substantial optical aberrations of the individual elements. Thus, as with multi-element lenses for light, a multi-element charged-particle lens can have optical behavior that is far superior to that of the individual elements. Transverse multiple-concentric-ring lenses achieve high performance, while also having advantages in terms of compactness and optical versatility.

  19. Transverse-structure electrostatic charged particle beam lens

    DOEpatents

    Moran, M.J.

    1998-10-13

    Electrostatic particle-beam lenses using a concentric co-planar array of independently biased rings can be advantageous for some applications. Traditional electrostatic lenses often consist of axial series of biased rings, apertures, or tubes. The science of lens design has devoted much attention to finding axial arrangements that compensate for the substantial optical aberrations of the individual elements. Thus, as with multi-element lenses for light, a multi-element charged-particle lens can have optical behavior that is far superior to that of the individual elements. Transverse multiple-concentric-ring lenses achieve high performance, while also having advantages in terms of compactness and optical versatility. 7 figs.

  20. The design of a compact pulse transformer

    Microsoft Academic Search

    J. ZHANGt; J. Dickens; M. Giesselmann; J. Kim; E. Kristiansen; J. Mankowski; D. Garcia; M. Kristiansen

    1999-01-01

    To improve the pulse shape and to obtain ?s order pulse duration on a diode load in an inductive energy storage system, an oil-submerged compact pulse transformer with diameter of 20 cm and length of 70 cm has been designed and tested. From theoretical calculations, the parameters with primary inductance Lp=3.4 ?H, secondary inductance Ls=90 ?H, and coupling coefficient K=0.772

  1. A compact CPW fed serrated UWB antenna

    Microsoft Academic Search

    V. A Shameena; Sarah Jacob; C. K Aanandan; K Vasudevan; P. Mohanan

    2011-01-01

    A compact CPW-fed planar monopole antenna for ultra-wideband applications is presented and investigated. The proposed antenna with a small size of 20 mm x26 mm x 1.6 mm is composed of a staircase shaped radiating element fed by a CPW feed line, and an inverted stair-style ground. The measured results agree reasonably with the simulated ones. The proposed antenna yields

  2. On compact weaker topologies in function spaces

    Microsoft Academic Search

    Fidel Casarrubias-Segura

    2001-01-01

    In this paper we prove that for every cardinal ?, the space Cp(D?) admits a continuous bijection onto a space whose all finite powers are Lindelöf (the symbol D stands for the discrete two-point space). We also prove that for every metrizable compact space X, the space Cp(X) can be condensed (i.e., admits a continuous bijection) onto the Hilbert cube

  3. Angular Diameters of Compact Planetary Nebulae

    E-print Network

    Timothy R. Bedding; Albert A. Zijlstra

    1993-09-14

    We have obtained H$\\alpha$ CCD images of 21 compact planetary nebulae in the galactic bulge. All objects are resolved and, after deconvolving the seeing disk, we find diameters of 1--2$''$ with typical uncertainties of 20\\%. The values are generally in good agreement with radio measurements but are smaller than older optical measurements. Based on the new values, we find that the Shklovsky method for distance determination greatly overestimates the actual distance for all of our objects.

  4. Infrared Imaging of Pharmaceutical Materials Undergoing Compaction

    Microsoft Academic Search

    Simon R. Bechard; G. R. B. Down

    1992-01-01

    The goal of this study was to use infrared thermography as a new technique to investigate the heat released during compaction and consolidation of pharmaceutical powders and granules. Real-time temperature measurements without physical contact with tablets were provided by a highly sensitive (±0.1°C at 30°C) infrared camera (Agema Infrared Systems, Model 470 with CM-SOFT software). High-resolution images were captured at

  5. A compact high voltage pulse generator

    SciTech Connect

    Rohwein, G.J.; Babcock, S.R.

    1994-07-01

    A compact, easily transportable, pulse generator has been developed for a variety of applications that require a pulse duration in the range of 1 {mu} sec., voltages from 150 to 300 KV and current levels from 2,000 to 3,000 amps. The generator has a simple cylindrical configuration and modular construction to facilitate assembly and service. The generator may be operated single-pulse or repetitively at pulse repetition rates to 50 Hz in a burst mode.

  6. Physics guidelines for the Compact Ignition Tokamak

    Microsoft Academic Search

    J. Sheffield; R. A. Dory; W. A. Houlberg; N. A. Uckan; M. Bell; P. Colestock; J. Hosea; S. Kaye; M. Petravic; D. Post

    1986-01-01

    The goal of the Compact Ignition Tokamak (CIT)d program is to provide a cost-effective route to the production of a burning deuterium-tritium plasma, so that alpha-particle effects may be studied. A key issue to be studied in the CIT is whether alpha power behaves like other power sources in affecting tokamak plasma confinement. The program is managed by the Princeton

  7. The UCLA compact high brightness electron accelerator

    Microsoft Academic Search

    P. Davis; G. Hairapetian; M. Hogan; C. Joshi; M. Lampel; C. Pellegrini; J. Rosenzweig; G. Travish; R. Zhang

    1995-01-01

    We report the characteristics and performance of the UCLA S-band compact electron accelerator, consisting of a high brightness, 8 cm long, photo-injector with a copper cathode, followed by a 42 cm long plane wave transformer accelerating structure, delivering a beam energy of 10 MeV. The photo-electrons are produced by a 266 nm laser pulse of less than 4 ps in

  8. The spheromak as a compact fusion reactor

    Microsoft Academic Search

    R. L. Hagenson; R. A. Krakowski

    1987-01-01

    After summarizing the economic and utility-based rationale for compact, higher-power-density fusion reactors, the gun-sustained spheromak concept is explored as one of a number of poloidal-field-dominated confinement configurations that might improve the prospects for economically attractive and operationally simplified fusion power plants. Using a comprehensive physics\\/engineering\\/costing model for the spheromak, guided by realistic engineering constraints and physics extrapolation, a range of

  9. Ultraviolet radiation emitted by compact fluorescent lamps

    Microsoft Academic Search

    Parag Sharma; V. K. Jaiswal; H. C. Kandpal

    2009-01-01

    To meet the objective of energy efficiency, increasing emphasis on use of energy saver compact fluorescent lamps (CFLs), makes\\u000a it necessary to analyze the effect of radiation especially ultraviolet (UV) radiation on human health. Various types of CFLs\\u000a in terms of various shapes, sizes and electrical powers are studied for UV content present in their radiation. Various parameters\\u000a such as

  10. Compact hydrogen\\/helium isotope mass spectrometer

    Microsoft Academic Search

    Herbert O. Funsten; David J. McComas; Earl E. Scime

    1996-01-01

    The compact hydrogen and helium isotope mass spectrometer of the present invention combines low mass-resolution ion mass spectrometry and beam-foil interaction technology to unambiguously detect and quantify deuterium (D), tritium (T), hydrogen molecule (H.sub.2, HD, D.sub.2, HT, DT, and T.sub.2), .sup.3 He, and .sup.4 He concentrations and concentration variations. The spectrometer provides real-time, high sensitivity, and high accuracy measurements. Currently,

  11. Light scalars from a compact fifth dimension

    Microsoft Academic Search

    Daniel Elander; Maurizio Piai

    2011-01-01

    We consider a general five-dimensional sigma-model coupled to gravity, with any number of scalars and general sigma-model\\u000a metric and potential. We discuss in detail the problem of the boundary conditions for the scalar fluctuations, in the case\\u000a where the fifth dimension is compact, and provide a simple (and very general) algorithmic procedure for computing the spectrum\\u000a of physical scalar fluctuations

  12. DNA methylation increases nucleosome compaction and rigidity.

    PubMed

    Choy, John S; Wei, Sijie; Lee, Ju Yeon; Tan, Song; Chu, Steven; Lee, Tae-Hee

    2010-02-17

    Cytosine methylation on CpG dinucleotides is an essential epigenetic modification in eukaryotes. How DNA methylation modulates nucleosome structure and dynamics has been a long-standing question. We implemented a single-molecule method to monitor the effects of DNA methylation on the structure and dynamics of mononucleosomes. Our studies show that DNA methylation induces a more compact and rigid nucleosome structure, providing a physical basis for how DNA methylation might contribute to regulating chromatin structure. PMID:20095602

  13. Starbursts in blue compact dwarf galaxies

    NASA Technical Reports Server (NTRS)

    Thuan, Trinh Xuan

    1987-01-01

    All the arguments for a bursting mode of star formation in blue compact dwarf galaxies (BCD) are summarized. It is shown that spectral synthesis of far-ultraviolet spectra of BCDs constitutes a powerful way to study the star formation history in these galaxies. BCD luminosity functions show jumps and discontinuities. These jumps act like fossil records of the star-forming bursts, aiding in the counting and dating of the bursts.

  14. Compact, Automated, Frequency-Agile Microspectrofluorimeter

    NASA Technical Reports Server (NTRS)

    Fernandez, Salvador M.; Guignon, Ernest F.

    1995-01-01

    Compact, reliable, rugged, automated cell-culture and frequency-agile microspectrofluorimetric apparatus developed to perform experiments involving photometric imaging observations of single live cells. In original application, apparatus operates mostly unattended aboard spacecraft; potential terrestrial applications include automated or semiautomated diagnosis of pathological tissues in clinical laboratories, biomedical instrumentation, monitoring of biological process streams, and portable instrumentation for testing biological conditions in various environments. Offers obvious advantages over present laboratory instrumentation.

  15. Compact Quiescent Galaxies at Intermediate Redshifts

    NASA Astrophysics Data System (ADS)

    Hsu, Li-Yen; Stockton, Alan; Shih, Hsin-Yi

    2014-12-01

    From several searches of the area common to the Sloan Digital Sky Survey and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we have selected 22 luminous galaxies between z ~ 0.4 and z ~ 0.9 that have colors and sizes similar to those of the compact quiescent galaxies at z > 2. By exploring structural parameters and stellar populations, we found that most of these galaxies actually formed most of their stars at z < 2 and are generally less compact than those found at z > 2. Several of these young objects are disk-like or possibly prolate. This lines up with several previous studies that found that massive quiescent galaxies at high redshifts often have disk-like morphologies. If these galaxies were to be confirmed to be disk-like, their formation mechanism must be able to account for both compactness and disks. On the other hand, if these galaxies were to be confirmed to be prolate, the fact that prolate galaxies do not exist in the local universe would indicate that galaxy formation mechanisms have evolved over cosmic time. We also found five galaxies forming over 80% of their stellar masses at z > 2. Three of these galaxies appear to have been modified to have spheroid-like morphologies, in agreement with the scenario of "inside-out" buildup of massive galaxies. The remaining galaxies, SDSS J014355.21+133451.4 and SDSS J115836.93+021535.1, have truly old stellar populations and disk-like morphologies. These two objects would be good candidates for nearly unmodified compact quiescent galaxies from high redshifts that are worth future study.

  16. Compact Structures in Standard Field Theory

    E-print Network

    D. Bazeia; L. Losano; M. A. Marques; R. Menezes

    2014-09-24

    We investigate the presence of static solutions in models described by real scalar field in two-dimensional spacetime. After taking advantage of a procedure introduced sometime ago, we solve intricate nonlinear ordinary differential equations and illustrate how to find compact structures in models engendering standard kinematics. In particular, we study linear stability and show that all the static solutions we have found are linearly stable.

  17. Compact-size coplanar waveguide bandpass filter

    Microsoft Academic Search

    Shry-Sann Liao; Pou-Tou Sun; Hsien-Ku Chen; Xian-Yuan Liao

    2003-01-01

    A compact-size coplanar waveguide (CPW) bandpass filter (BPF) is proposed. In this study, we use the bended stub with novel folded skill to improve the three parallel coupled-lines structure of BPF for N = 1. It gets the sharp transition band (TB) and reduces the dimension of the circuit by 66.67% at 2.45 GHz. Its center frequency can be shifted

  18. VLBI Observations of Five Compact Radio Sources

    E-print Network

    J. F. Zhou; D. R. Jiang; X. Y. Hong; T. Venturi

    2000-09-26

    Five compact radio sources, include 0420-014, 1334-127, 1504-166, 2243-123, and 2345-167, were observed at 5GHz by European VLBI (Very Long Baseline Interferometry) Network (EVN) in June, 1996. The primary purpose of this observation was to confirm their superluminal proper motions. Here, the results of 1334-127, 1504-166, 2243-123 and 2345-167 are presented.

  19. ROSAT: X ray survey of compact groups

    NASA Technical Reports Server (NTRS)

    Vangorkom, Jacqueline

    1993-01-01

    This is the final technical report on grant NAG5-1954, which was awarded under the NASA ROSAT Guest Investigator Program to Columbia University. This grant was awarded for a number of projects on two rather different topics: (1) an x-ray survey of compact groups of galaxies; and (2) the fate of gas in merging galaxies. Progress made in these projects is presented.

  20. Light, Compact Pumper for Harbor Fires

    NASA Technical Reports Server (NTRS)

    Burns, R. A.

    1983-01-01

    Report describes development of new transportable water-pumping unit for fire-fighting. Compact, self-contained unit provides fire protection at coastal and inland ports and is lighter than standard firetruck pumper of same capacity. Used to fight fires in harbors, cities, forests, refineries, chemical plants, and offshore drilling platforms. Other possible applications include cleaning up oilspills, pumping out ships, and flood control pumping.

  1. Effects of Compaction and Temperature on Sorption and Diffusion of Cs and HTO in Compacted Bentonite Saturated with Saline Water

    SciTech Connect

    Satoru Suzuki; Masashi Haginuma; Kazunori Suzuki [Nuclear Chemistry and Chemical Engineering Center, Institute of Research and Innovation, 1201 Takada, Kashiwa, 277-0861 (Japan)

    2007-07-01

    The sorption and diffusion of Cs and tritiated water (HTO) in compacted bentonite was investigated at temperatures from 30 to 60 deg. C. The apparent (D{sub a}) and effective (D{sub e}) diffusion coefficients were determined by in-diffusion and through-diffusion experiments with a constant boundary concentration maintained. The temperature dependence of De and Da obeyed an Arrhenius-type equation, allowing determination of the activation energy for diffusion of Cs and HTO. The D{sub e} value of Cs was three times the D{sub e} of HTO, which is considered to be a result of surface-excess diffusion. Cs may be concentrated near the surface of the negatively charged clay, thus giving a large diffusive flux. The activation energies for Cs diffusion were 21.4{+-}2.8 kJ/mol and 37.3{+-}1.5 kJ/mol as determined based on D{sub e} and D{sub a}, respectively. This difference was due to the temperature dependence of the distribution coefficient K{sub d} of Cs. (authors)

  2. The Evolution of Compact Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Postnov, Konstantin A.; Yungelson, Lev R.

    2014-05-01

    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Mergings of compact-star binaries are expected to be the most important sources for forthcoming gravitational-wave (GW) astronomy. In the first part of the review, we discuss observational manifestations of close binaries with NS and/or BH components and their merger rate, crucial points in the formation and evolution of compact stars in binary systems, including the treatment of the natal kicks, which NSs and BHs acquire during the core collapse of massive stars and the common envelope phase of binary evolution, which are most relevant to the merging rates of NS-NS, NS-BH and BH-BH binaries. The second part of the review is devoted mainly to the formation and evolution of binary WDs and their observational manifestations, including their role as progenitors of cosmologically-important thermonuclear SN Ia. We also consider AM CVn-stars, which are thought to be the best verification binary GW sources for future low-frequency GW space interferometers.

  3. Computing CMB Anisotropy in Compact Hyperbolic Spaces

    E-print Network

    J. Richard Bond; Dmitri Pogosyan; Tarun Souradeep

    1998-07-09

    The measurements of CMB anisotropy have opened up a window for probing the global topology of the universe on length scales comparable to and beyond the Hubble radius. For compact topologies, the two main effects on the CMB are: (1) the breaking of statistical isotropy in characteristic patterns determined by the photon geodesic structure of the manifold and (2) an infrared cutoff in the power spectrum of perturbations imposed by the finite spatial extent. We present a completely general scheme using the regularized method of images for calculating CMB anisotropy in models with nontrivial topology, and apply it to the computationally challenging compact hyperbolic topologies. This new technique eliminates the need for the difficult task of spatial eigenmode decomposition on these spaces. We estimate a Bayesian probability for a selection of models by confronting the theoretical pixel-pixel temperature correlation function with the COBE-DMR data. Our results demonstrate that strong constraints on compactness arise: if the universe is small compared to the `horizon' size, correlations appear in the maps that are irreconcilable with the observations. If the universe is of comparable size, the likelihood function is very dependent upon orientation of the manifold wrt the sky. While most orientations may be strongly ruled out, it sometimes happens that for a specific orientation the predicted correlation patterns are preferred over the conventional infinite models.

  4. Constraints on Compact Hyperbolic Spaces from COBE

    E-print Network

    J. Richard Bond; Dmitry Pogosyan; Tarun Souradeep

    1997-02-25

    The (large angle) COBE DMR data can be used to probe the global topology of our universe on scales comparable to and just beyond the present ``horizon''. For compact topologies, the two main effects on the CMB are: [1] the breaking of statistical isotropy in characteristic patterns determined by the photon geodesic structure of the manifold and [2] an infrared cutoff in the power spectrum of perturbations imposed by the finite spatial extent. To make a detailed confrontation of these effects with the COBE maps requires the computation of the pixel-pixel temperature correlation function for each topology and for each orientation of it relative to the sky. We present a general technique using the method of images for doing this in compact hyperbolic (CH) topologies which does not require spatial eigenmode decomposition. We demonstrate that strong constraints on compactness follow from [2] and that these limits can be improved by exploiting the details of the geodesic structure for each individual topology ([1]), as we show for the flat 3-torus and selected CH models.

  5. Electrothermal Defect Detection in Powder Metallurgy Compacts

    NASA Astrophysics Data System (ADS)

    Benzerrouk, Souheil; Ludwig, Reinhold; Apelian, Diran

    2006-03-01

    Faced with increasing market pressures, metal part manufacturers have turned to new processes and fabrication technologies. One of these processes is powder metallurgy (P/M), which is employed for low-cost, high-volume precision part manufacturing. Despite many advantages, the P/M process has created a number of challenges, including the need for high-speed quality assessment and control, ideally for each compact. Consequently, sophisticated quality assurance is needed to rapidly detect flaws early in the manufacturing cycle and at minimal cost. In this paper we will discuss our progress made in designing and refining an active infrared (IR) detection system for P/M compacts. After discussing the theoretical background in terms of underlying equations and boundary conditions, analytical and numerical solutions are presented that are capable of predicting temperature responses for various defect sizes and orientations of a dynamic IR testing system. Preliminary measurements with controlled and industrial samples have shown that this active IR methodology can successfully be employed to test both green-state and sintered P/M compacts. The developed system can overcome many limitations observed with a standard IR testing methodology such as emissivity, background calibration, and contact resistance.

  6. Vibratory Shock Compaction of Granular Nuclear Waste

    NASA Astrophysics Data System (ADS)

    Amme, Robert C.

    2004-05-01

    Vibratory Shock Compaction (VSC) is a proven means for quickly forming strong, durable solids from a wide variety of granular materials[1]. Calcination of tank and other forms of high level radioactive wastes results in fine granular material that is quite amenable to volume reduction and stabilization. We have employed utilities coal ash as a calcine waste surrogate, blended with a quartz/feldspar-rich sand and 0-20% proportions of a borosilicate glass. The blends were compacted at room temperature and fired so that the glass melt could form an efficient binder. Included in the blend are small quantities of three RCRA metals, chromium, cadmium and lead, to permit testing for heavy metal stability. The VSC process is described and the results presented in terms of the waste form dissolution rates, compressive strengths, elastic moduli as determined from resonant frequency measurements, and heavy metal leach rates from Toxicity Characteristic Leaching Procedure measurements. Vibratory shock compaction employing glass binders appears to be a viable alternative to traditional vitrification processes for granular waste forms. [1] See http://www.resonantshockcompact.com

  7. The compactness of presupernova stellar cores

    SciTech Connect

    Sukhbold, Tuguldur; Woosley, S. E., E-mail: sukhbold@ucolick.org [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2014-03-01

    The success or failure of the neutrino-transport mechanism for producing a supernova in an evolved massive star is known to be sensitive not only to the mass of the iron core that collapses, but also to the density gradient in the silicon and oxygen shells surrounding that core. Here we study the systematics of a presupernova core's 'compactness' as a function of the mass of the star and the physics used in its calculation. Fine-meshed surveys of presupernova evolution are calculated for stars from 15 to 65 M {sub ?}. The metallicity and the efficiency of semiconvection and overshoot mixing are both varied and bare carbon-oxygen cores are explored as well as full hydrogenic stars. Two different codes, KEPLER and MESA, are used for the study. A complex interplay of carbon and oxygen burning, especially in shells, can cause rapid variations in the compactness for stars of very nearly the same mass. On larger scales, the distribution of compactness with main sequence mass is found to be robustly non-monotonic, implying islands of 'explodabilty,' particularly around 8-20 M {sub ?} and 25-30 M {sub ?}. The carbon-oxygen (CO) core mass of a presupernova star is a better, (though still ambiguous) discriminant of its core structure than the main sequence mass.

  8. Compact high-speed scanning lidar system

    NASA Astrophysics Data System (ADS)

    Dickinson, Cameron; Hussein, Marwan; Tripp, Jeff; Nimelman, Manny; Koujelev, Alexander

    2012-06-01

    The compact High Speed Scanning Lidar (HSSL) was designed to meet the requirements for a rover GN&C sensor. The eye-safe HSSL's fast scanning speed, low volume and low power, make it the ideal choice for a variety of real-time and non-real-time applications including: 3D Mapping; Vehicle guidance and Navigation; Obstacle Detection; Orbiter Rendezvous; Spacecraft Landing / Hazard Avoidance. The HSSL comprises two main hardware units: Sensor Head and Control Unit. In a rover application, the Sensor Head mounts on the top of the rover while the Control Unit can be mounted on the rover deck or within its avionics bay. An Operator Computer is used to command the lidar and immediately display the acquired scan data. The innovative lidar design concept was a result of an extensive trade study conducted during the initial phase of an exploration rover program. The lidar utilizes an innovative scanner coupled with a compact fiber laser and high-speed timing electronics. Compared to existing compact lidar systems, distinguishing features of the HSSL include its high accuracy, high resolution, high refresh rate and large field of view. Other benefits of this design include the capability to quickly configure scan settings to fit various operational modes.

  9. Enhancement of griseofulvin release from liquisolid compacts.

    PubMed

    Hentzschel, C M; Alnaief, M; Smirnova, I; Sakmann, A; Leopold, C S

    2012-01-01

    The potential of hydrophilic aerogel formulations and liquisolid systems to improve the release of poorly soluble drugs was investigated using griseofulvin as model drug. The in vitro release rates of this drug formulated as directly compressed tablets containing crystalline griseofulvin were compared to aerogel tablets with the drug adsorbed onto hydrophilic silica aerogel and to liquisolid compacts containing the drug dissolved or suspended in PEG 300. Furthermore, the commonly used carrier and coating materials in liquisolid systems Avicel® and Aerosil® were replaced by Neusilin®, an amorphous magnesium aluminometasilicate with an extremely high specific surface area of 339 m²/g to improve the liquisolid approach. Both the liquisolid compacts containing the drug dissolved in PEG 300 and the aerogel tablets showed a considerably faster drug release than the directly compressed tablets. With liquisolid compacts containing the drug suspended in PEG 300, the release rate increased with rising fraction of dissolved drug in the liquid portion. It could be shown that Neusilin® with its sevenfold higher liquid adsorption capacity than the commonly used Avicel® and Aerosil® allows the production of liquisolid formulations with lower tablet weights. PMID:21846502

  10. Controlling charge on levitating drops.

    PubMed

    Hilger, Ryan T; Westphall, Michael S; Smith, Lloyd M

    2007-08-01

    Levitation technologies are used in containerless processing of materials, as microscale manipulators and reactors, and in the study of single drops and particles. Presented here is a method for controlling the amount and polarity of charge on a levitating drop. The method uses single-axis acoustic levitation to trap and levitate a single, initially neutral drop with a diameter between 400 microm and 2 mm. This drop is then charged in a controllable manner using discrete packets of charge in the form of charged drops produced by a piezoelectric drop-on-demand dispenser equipped with a charging electrode. The magnitude of the charge on the dispensed drops can be adjusted by varying the voltage applied to the charging electrode. The polarity of the charge on the added drops can be changed allowing removal of charge from the trapped drop (by neutralization) and polarity reversal. The maximum amount of added charge is limited by repulsion of like charges between the drops in the trap. This charging scheme can aid in micromanipulation and the study of charged drops and particles using levitation. PMID:17580951

  11. Role of particle charge in impact ionization by charged microparticles

    Microsoft Academic Search

    M. J. Burchell; M. J. Cole; J. A. M. McDonnell

    1998-01-01

    The role of particle charge in generating ionization of projectile and target in impacts of iron microparticles on copper has been investigated at impact velocities above 1 km s?1. Charged microparticles are accelerated in an electrostatic accelerator and their surface charge subsequently reduced in flight by passage through a thin conducting film. It is found that a reduction in projectile

  12. Discrete charge dielectric model of electrostatic energy

    Microsoft Academic Search

    Tim LaFave

    2011-01-01

    Studies on nanoscale materials merit careful development of an electrostatics model concerning discrete point charges within dielectrics. The discrete charge dielectric model treats three unique interaction types derived from an external source: Coulomb repulsion among point charges, direct polarization between point charges and their associated surface charge elements, and indirect polarization between point charges and surface charge elements formed by

  13. Charge detection in semiconductor nanostructures

    E-print Network

    MacLean, Kenneth (Kenneth MacLean, III)

    2010-01-01

    In this thesis nanometer scale charge sensors are used to study charge transport in two solid state systems: Lateral GaAs quantum dots and hydrogenated amorphous silicon (a-Si:H). In both of these experiments we use ...

  14. Perturbatively charged holographic disorder

    E-print Network

    O'Keeffe, Daniel K

    2015-01-01

    Within the framework of holography applied to condensed matter physics, we study a model of perturbatively charged disorder in D=4 dimensions. Starting from initially uncharged AdS_4, a randomly fluctuating boundary chemical potential is introduced by turning on a bulk gauge field parameterized by a disorder strength and a characteristic scale k_0. Accounting for gravitational backreaction, we construct an asymptotically AdS solution perturbatively in the disorder strength. The disorder averaged geometry displays unphysical divergences in the deep interior. We explain how to remove these divergences and arrive at a well behaved solution. The disorder averaged DC conductivity is calculated and is found to contain a correction to the AdS result. The correction appears at second order in the disorder strength and scales inversely with k_0. We discuss the extension to a system with a finite initial charge density. The disorder averaged DC conductivity may be calculated by adopting a technique developed for hologr...

  15. Perturbatively charged holographic disorder

    E-print Network

    Daniel K. O'Keeffe; Amanda W. Peet

    2015-04-13

    Within the framework of holography applied to condensed matter physics, we study a model of perturbatively charged disorder in D=4 dimensions. Starting from initially uncharged AdS_4, a randomly fluctuating boundary chemical potential is introduced by turning on a bulk gauge field parameterized by a disorder strength and a characteristic scale k_0. Accounting for gravitational backreaction, we construct an asymptotically AdS solution perturbatively in the disorder strength. The disorder averaged geometry displays unphysical divergences in the deep interior. We explain how to remove these divergences and arrive at a well behaved solution. The disorder averaged DC conductivity is calculated and is found to contain a correction to the AdS result. The correction appears at second order in the disorder strength and scales inversely with k_0. We discuss the extension to a system with a finite initial charge density. The disorder averaged DC conductivity may be calculated by adopting a technique developed for holographic lattices.

  16. Dynamics of Gravitomagnetic Charge

    E-print Network

    Shen, J Q

    2003-01-01

    The physically interesting gravitational analogue of magnetic monopole in electrodynamics is considered in the present paper. The author investigates the field equation of gravitomagnetic matter, and the exact static cylindrically symmetric solution of field equation as well as the motion of gravitomagnetic charge in gravitational fields. Use is made of the mechanism of gravitational Meissner effect, a potential interpretation of anomalous, constant, acceleration acting on the Pioneer 10/11, Galileo and Ulysses spacecrafts is also suggested.

  17. CHARGE syndrome: an update

    Microsoft Academic Search

    Damien Sanlaville; Alain Verloes

    2007-01-01

    CHARGE syndrome is a rare, usually sporadic autosomal dominant disorder due in 2\\/3 of cases to mutations within the CHD7 gene. The clinical definition has evolved with time. The 3C triad (Coloboma-Choanal atresia-abnormal semicircular Canals), arhinencephaly and rhombencephalic dysfunctions are now considered the most important and constant clues to the diagnosis. We will discuss here recent aspects of the phenotypic

  18. Energetic Charged Particles Produced in the Gas Phase by Electrolysis

    NASA Astrophysics Data System (ADS)

    Oriani, R. A.; Fisher, J. C.

    2005-12-01

    CR-39 plastic detector chips suspended in the vapor over the electrolytic solution during electrolysis record the tracks of highly energetic charged particles. The probability that the track densities found in these detector chips and the generally smaller track densities found in controls belong to a common population is 3 × 10-10 by the Mann-Whitney statistical test. It is therefore concluded that a nuclear reaction that originates in the vapor phase can accompany electrolysis. Occasionally huge numbers of nuclear tracks are recorded by detector chips in the vapor over active electrolysis cells. One such experiment is analyzed in which two contiguous detector chips recorded approximately 40,000 tracks. Analysis of track orientations shows that the shower of charged particles originated in a compact source in the vapor between the chips at about 2 mm from one of the chips. A new type of nuclear reaction is indicated.

  19. The effect of TiO2 nanoflowers as a compact layer for CdS quantum-dot sensitized solar cells with improved performance.

    PubMed

    Rao, S Srinivasa; Durga, I Kanaka; Gopi, Chandu V V M; Venkata Tulasivarma, Chebrolu; Kim, Soo-Kyoung; Kim, Hee-Je

    2015-07-01

    Currently, TiO2 on a fluorine-doped tin oxide substrate is the most commonly used type of photoelectrode in high-efficiency quantum dot-sensitized solar cells (QDSSCs). The power conversion efficiency (PCE) of TiO2 photoelectrodes is limited because of higher charge recombination and lower QD loading on the TiO2 film. This article describes the effect of a TiO2 compact layer on a TiO2 film to enhance the performance of QDSSCs. TiO2 nanoparticles were coated on an FTO substrate by the doctor-blade method and then the TiO2 compact layer was successfully fabricated on the surface of the nanoparticles by a simple hydrothermal method. QDSSCs were made using these films as photoelectrodes with NiS counter electrodes. Under one sun illumination (AM 1.5 G, 100 mW cm(-2)), the QDSSCs showed PCEs of 2.19 and 2.93% for TCL1 and TCL2 based photoelectrodes, which are higher than the 1.33% value obtained with bare TiO2. The compact-layer-coated film electrodes provide a lower charge-transfer resistance and higher light harvesting. The compact layer on the TiO2 film is a more efficient photocatalyst than pure TiO2 film and physically separates the injected electrons in the TiO2 from the positively charged CdS QD/electrolyte. PMID:26102365

  20. Tools for charged Higgs bosons

    E-print Network

    Oscar Stål

    2010-12-13

    We review the status of publicly available software tools applicable to charged Higgs physics. A selection of codes are highlighted in more detail, focusing on new developments that have taken place since the previous charged Higgs workshop in 2008. We conclude that phenomenologists now have the tools ready to face the LHC data. A new webpage collecting charged Higgs resources is presented.

  1. Electrophoretically Assessing Polyelectrolyte Effective Charge

    Microsoft Academic Search

    Alexey Popov; David Hoagland

    2006-01-01

    Capillary electrophoresis revealed how polyelectrolyte effective charge density varies with backbone charge spacing and solvent dielectric constant. The study focused on ionenes, polyelectrolytes that possess regularly spaced quaternary ammonium groups in the backbone. Complete ionization of functional units and good solvency in water and mixtures of water with methanol or acetonitrile enabled measurements of ionene effective charge density as solvent

  2. Charging Users for Library Service.

    ERIC Educational Resources Information Center

    Cooper, Michael D.

    1978-01-01

    Examines the question of instituting direct charges for library service, using on-line bibliographic searching as an example, and contrasts this with the current indirect charging system where services are paid for by taxes. Information, as a merit good, should be supplied with or without direct charges, depending upon user status. (CWM)

  3. Structure and expression of a novel compact myelin protein – Small VCP-interacting protein (SVIP)

    SciTech Connect

    Wu, Jiawen [Department of Neurology, Vanderbilt University School of Medicine (United States)] [Department of Neurology, Vanderbilt University School of Medicine (United States); Peng, Dungeng [Department of Biochemistry, Vanderbilt University School of Medicine (United States)] [Department of Biochemistry, Vanderbilt University School of Medicine (United States); Voehler, Markus [Center for Structural Biology, Vanderbilt University (United States)] [Center for Structural Biology, Vanderbilt University (United States); Sanders, Charles R. [Department of Biochemistry, Vanderbilt University School of Medicine (United States) [Department of Biochemistry, Vanderbilt University School of Medicine (United States); Center for Structural Biology, Vanderbilt University (United States); Li, Jun, E-mail: jun.li.2@vanderbilt.edu [Department of Neurology, Vanderbilt University School of Medicine (United States) [Department of Neurology, Vanderbilt University School of Medicine (United States); Tennessee Valley Healthcare System (TVHS) – Nashville VA (United States)

    2013-10-11

    Highlights: •SVIP (small p97/VCP-interacting protein) co-localizes with myelin basic protein (MBP) in compact myelin. •We determined that SVIP is an intrinsically disordered protein (IDP). •The helical content of SVIP increases dramatically during its interaction with negatively charged lipid membrane. •This study provides structural insight into interactions between SVIP and myelin membranes. -- Abstract: SVIP (small p97/VCP-interacting protein) was initially identified as one of many cofactors regulating the valosin containing protein (VCP), an AAA+ ATPase involved in endoplasmic-reticulum-associated protein degradation (ERAD). Our previous study showed that SVIP is expressed exclusively in the nervous system. In the present study, SVIP and VCP were seen to be co-localized in neuronal cell bodies. Interestingly, we also observed that SVIP co-localizes with myelin basic protein (MBP) in compact myelin, where VCP was absent. Furthermore, using nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopic measurements, we determined that SVIP is an intrinsically disordered protein (IDP). However, upon binding to the surface of membranes containing a net negative charge, the helical content of SVIP increases dramatically. These findings provide structural insight into interactions between SVIP and myelin membranes.

  4. Submerged AUV Charging Station

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Chao, Yi; Curtin, Thomas

    2014-01-01

    Autonomous Underwater Vehicles (AUVs) are becoming increasingly important for military surveillance and mine detection. Most AUVs are battery powered and have limited lifetimes of a few days to a few weeks. This greatly limits the distance that AUVs can travel underwater. Using a series of submerged AUV charging stations, AUVs could travel a limited distance to the next charging station, recharge its batteries, and continue to the next charging station, thus traveling great distances in a relatively short time, similar to the Old West “Pony Express.” One solution is to use temperature differences at various depths in the ocean to produce electricity, which is then stored in a submerged battery. It is preferred to have the upper buoy submerged a reasonable distance below the surface, so as not to be seen from above and not to be inadvertently destroyed by storms or ocean going vessels. In a previous invention, a phase change material (PCM) is melted (expanded) at warm temperatures, for example, 15 °C, and frozen (contracted) at cooler temperatures, for example, 8 °C. Tubes containing the PCM, which could be paraffin such as pentadecane, would be inserted into a container filled with hydraulic oil. When the PCM is melted (expanded), it pushes the oil out into a container that is pressurized to about 3,000 psi (approx equals 20.7 MPa). When a valve is opened, the high-pressure oil passes through a hydraulic motor, which turns a generator and charges a battery. The low-pressure oil is finally reabsorbed into the PCM canister when the PCM tubes are frozen (contracted). Some of the electricity produced could be used to control an external bladder or a motor to the tether line, such that depth cycling is continued for a very long period of time. Alternatively, after the electricity is generated by the hydraulic motor, the exiting low-pressure oil from the hydraulic motor could be vented directly to an external bladder on the AUV, such that filling of the bladder causes the AUV to rise, and emptying of the bladder allows the AUV to descend. This type of direct buoyancy control is much more energy efficient than using electrical pumps in that the inefficiencies of converting thermal energy to electrical energy to mechanical energy is avoided. AUV charging stations have been developed that use electricity produced by waves on floating buoys and that use electricity from solar photovoltaics on floating buoys. This is the first device that has absolutely no floating or visible parts, and is thus impervious to storms, inadvertent ocean vessel collisions, or enemy sabotage.

  5. Compact Quantum Dots for Single-molecule Imaging

    PubMed Central

    Smith, Andrew M.; Nie, Shuming

    2012-01-01

    Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study. Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7. Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm). PMID:23093375

  6. Compact Q=2 Abelian Higgs model in the London limit: Vortex-monopole chains and the photon propagator

    SciTech Connect

    Chernodub, M.N. [ITEP, Bolshaya Cheremushkinskaja 25, Moscow, 117218 (Russian Federation); Feldmann, R.; Schiller, A. [Institut fuer Theoretische Physik and NTZ, Universitaet Leipzig, D-04109 Leipzig (Germany); Ilgenfritz, E.-M. [Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany)

    2005-04-01

    The confining and topological properties of the compact Abelian Higgs model with doubly-charged Higgs field in three space-time dimensions are studied. We consider the London limit of the model. We show that the monopoles are forming chainlike structures (kept together by Abrikosov-Nielsen-Olesen vortices), the presence of which is essential for getting simultaneously permanent confinement of singly-charged particles and breaking of the string spanned between doubly-charged particles. In the confinement phase, the chains are forming percolating clusters, while in the deconfinement (Higgs) phase, the chains are of finite size. The described picture is in close analogy with the synthesis of the Abelian monopole and the center vortex pictures in confining non-Abelian gauge models. The screening properties of the vacuum are studied by means of the photon propagator in the Landau gauge.

  7. Development of a compact tomography camera system using a multianode photomultiplier tube for compact torus experiments.

    PubMed

    Tomuro, H; Asai, T; Iguchi, K; Takahashi, Ts; Hirano, Y

    2010-10-01

    A compact tomography camera system consisting of a photomultiplier tube, a multislit optical system, and a band-pass interference filter has been developed. The viewing area and spatial resolution can be configured by the arrangement of the slit system. The camera system has been specially designed for self-organized compact torus experiments having strong magnetohydrodynamics events with a submicrosecond time-scale. The developed system has been tested on a field-reversed configuration formed by the field-reversed theta-pinch. Performance evaluation of the system has been performed by comparison to the former optical system. PMID:21034053

  8. Fractional charges and Misner-Wheeler charge without charge effect in metamaterials

    E-print Network

    Igor I. Smolyaninov

    2014-12-08

    Optical space in metamaterials may be engineered to emulate four dimensional Kaluza-Klein theory. Nonlinear optics of such metamaterials mimics interaction of quantized electric charges. An electromagnetic wormhole is designed, which connects two points of such an optical space and changes its effective topology. Electromagnetic field configurations which exhibit fractional charges appear as a result of such topology change. Moreover, such effects as Misner-Wheeler charge without charge may be replicated.

  9. Collisional charging of interstellar grains

    SciTech Connect

    Draine, B.T.; Sutin, B.

    1987-09-01

    Collisional charging of small interstellar particles is reexamined, including effects due to electrostatic polarization of grains by the electric fields of approaching charged particles. The interaction potentials and resulting energy-dependent collisional cross sections are discussed and used to obtain the collisional charging rate for grains of specified charges in a thermal plasma. The probability distribution of the grain charges is obtained, and the application of the results to the interstellar medium is illustrated by considering the power-law grain size distribution of Mathis, Rumpl, and Nordsieck (1977). It is found that dust grains with such a size distribution can contribute appreciably to the recombination of metal ions in dark clouds.

  10. Chemically induced compaction bands in geomaterials

    NASA Astrophysics Data System (ADS)

    Stefanou, Ioannis; Sulem, Jean

    2013-04-01

    Compaction bands play an important role in oil production and may provide useful information on various geological processes. Various mechanisms can be involved at different scales: the micro scale (e.g. the grain scale), the meso scale (e.g. the Representative Element Volume) and the macro scale (e.g. the structure). Moreover, hydro-chemo-mechanical couplings might play an important role in triggering instabilities in the form of compaction bands. Compaction bands can be seen as an instability of the underneath mathematical problem leading to localization of deformation [1,2,3]. Here we explore the conditions of compaction banding in quartz-based geomaterials by considering the effect of chemical dissolution and precipitation [4,5]. In due course of the loading process grain crushing affects the residual strength, the porosity and the permeability of the material. Moreover, at the micro-level, grain crushing results in an increase of the grain specific surface, which accelerates the dissolution [6]. Consequently, the silica is removed more rapidly from the grain skeleton and the overall mechanical properties are degraded due to chemical factors. The proposed model accounts for these phenomena. In particular, the diffusion of the diluted in the water silica is considered through the mass balance equation of the porous medium. The reduction of the mechanical strength of the material is described through a macroscopic failure criterion with chemical softening. The grain size reduction is related to the total energy input [7]. A grain size and porosity dependent permeability law is adopted. These degradation mechanisms are coupled with the dissolution/precipitation reaction kinetics. The obtained hydro-chemo-mechanical model is used to investigate the conditions, the material parameters and the chemical factors inducing compaction bands formation. References [1] J.W. Rudnicki, and J.R. Rice. "Conditions for the Localization of Deformation in Pressure-sensitive Dilatant Materials." Journal of the Mechanics and Physics of Solids 23.6 (1975): 371-394. [2] I. Vardoulakis and J. Sulem: Bifurcation analysis in geomechanics. Blackie. 1995. [3] J.W. Rudnicki, "Conditions for Compaction and Shear Bands in a Transversely Isotropic Material." International Journal of Solids and Structures 39.13-14 (2002): 3741-3756. [4] L.-B. Hu and T. Hueckel. "Coupled Chemo-mechanics of Intergranular Contact: Toward a Three-scale Model." Computers and Geotechnics 34.4 (2007): 306-327. [5] R. Nova, R. Castellanza, and C. Tamagnini. "A Constitutive Model for Bonded Geomaterials Subject to Mechanical And/or Chemical Degradation." International Journal for Numerical and Analytical Methods in Geomechanics 27.9 (2003): 705-732. [6] J.D. Rimstidt and H.L. Barnes. "The Kinetics of Silica-water Reactions." Geochimica et Cosmochimica Acta 44.11 (1980): 1683-1699. [7] P.V. Lade, J.A. Yamamuro and P.A. Bopp "Significance of Particle Crushing in Granular Materials." Journal of Geotechnical Engineering, 122.4 (1996): 309-316.

  11. CYANATE ION IN COMPACT AMORPHOUS WATER ICE

    SciTech Connect

    Mate, Belen; Herrero, Victor J.; Rodriguez-Lazcano, Yamilet; Moreno, Miguel A.; Escribano, Rafael [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, E-28006 Madrid (Spain); Fernandez-Torre, Delia [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28050 Madrid (Spain); Gomez, Pedro C. [Departamento de Quimica Fisica I, Universidad Complutense, Unidad Asociada UCM-CSIC, E-28040 Madrid (Spain)

    2012-11-10

    The 4.62 {mu}m infrared (2164.5 cm{sup -1}) absorption band, observed in ice mantels toward many young stellar objects, has been mostly attributed to the {nu}{sub 3} (CN stretch) band of OCN{sup -} ions. We present in this work a spectroscopic study of OCN{sup -} ions embedded in compact amorphous ice in a range of concentrations and temperatures relevant to astronomical observations together with quantum mechanical calculations of the {nu}{sub 3} band of OCN{sup -} in various H{sub 2}O environments. The ice samples containing the ions are prepared through hyperquenching of liquid droplets of K{sup +}OCN{sup -} solutions on a substrate at 14 K. The {nu}{sub 3} OCN{sup -} band appears as a broad feature peaking at 4.64 {mu}m with a secondary maximum at 4.54 {mu}m and is much weaker than the corresponding peak in the liquid solution or in the solid salt. A similar weakening is observed for other OCN{sup -} absorption peaks at 7.66 {mu}m (2{nu}{sub 2}) and 8.20 {mu}m ({nu}{sub 1}). The theoretical calculations for the {nu}{sub 3} vibration lead to a range of frequencies spanning the experimentally observed width. This frequency spread could help explain the pronounced drop in the band intensity in the ice. The OCN{sup -} {nu}{sub 3} band in the present compact ices is also broader and much weaker than that reported in the literature for OCN{sup -} ions obtained by variously processing porous ice samples containing suitable neutral precursors. The results of this study indicate that the astronomical detection of OCN{sup -} in ice mantels could be significantly impaired if the ion is embedded in a compact water network.

  12. Acceleration of compact toruses and fusion applications

    SciTech Connect

    Hartman, C.W.; Eddleman, J.L.; Hammer, J.H.; Logan, B.G.; McLean, H.S.; Molvik, A.W.

    1990-10-11

    The Compact Torus (Spheromak-type) is a near ideal plasma confinement configuration for acceleration. The fields are mostly generated by internal plasma currents, plasma confinement is toroidal, and the compact torus exhibits resiliency and stability in virtue of the ``rugged`` helicity invariant. Based on these considerations we are developing a coaxial rail-gun type Compact Torus Accelerator (CTA). In the CTA, the CT ring is formed between coaxial electrodes using a magnetized Marshall gun, it is quasistatically ``precompressed`` in a conical electrode section for inductive energy storage, it is accelerated in a straight-coaxial electrode section as in a conventional rail-gun, and it is focused to small size and high energy and power density in a final ``focus`` cone section. The dynamics of slow precompression and acceleration have been demonstrated experimentally in the RACE device with results in good agreement with 2-D MHD code calculations. CT plasma rings with 100 {micro}gms mass have been accelerated to 40 Kj kinetic energy at 20% efficiency with final velocity = 1 X 10{sup 8} cm/s (= 5 KeV/H{sup +}). Preliminary focus tests exhibi dynamics of radius compression, deceleration, and bouncing. Compression ratios of 2-3 have been achieved. A scaled-up 10-100 MJ CTA is predicted to achieve a focus radius of several cm to deliver = 30 MJ ring kinetic energy in 5-10 nsec. This is sufficient energy, power, and power density to enable the CTA to act as a high efficiency, low cost ICF driver. Alternatively, the focused CT can form the basis for an magnetically insulated, inertial confinement fusion (MICF) system. Preliminary calculations of these fusion systems will be discussed.

  13. A novel compact real time radiation detector.

    PubMed

    Li, Shiping; Xu, Xiufeng; Cao, Hongrui; Tang, Shibiao; Ding, Baogang; Yin, Zejie

    2012-08-01

    A novel compact real time radiation detector with cost-effective, ultralow power and high sensitivity based on Geiger counter is presented. The power consumption of this detector which employs CMOS electro circuit and ultralow-power microcontroller is down to only 12.8 mW. It can identify the presences of 0.22 ?Ci (60)Co at a distance of 1.29 m. Furthermore, the detector supports both USB bus and serial interface. It can be used for personal radiation monitoring and also fits the distributed sensor network for radiation detection. PMID:22738843

  14. Compact gas insulated transformer. Fifteenth quarterly report

    SciTech Connect

    Not Available

    1984-01-01

    The overall objective of this program is to develop new technologies for application in a radically new power transformer design. The specific objective lies in designing a transformer which is more efficient, more compact, lower in weight and audible sound, nonflammable, which does not rely upon mineral oil insulation, and which is compatible with the gas-insulated electrical system of the future. This program has as its goal the development of design and manufacturing technology. Design prototypes in the 50 MVA-345 kV range will be tested. In addition to the development of technologies, the program provides for economic, environmental, and systems application assessments of the emergent technologies.

  15. Compact fluorescent lamp applications in luxury hotels

    SciTech Connect

    Gilleskie, R.J.

    1996-01-01

    Over the past several years, consumers, lighting designers, and energy conservationists have paid increasing attention to the special characteristics of compact fluorescent lamps (CFLs). CFLs can typically be used to replace incandescent lamps of three to four times their own wattage, and their color rendering indices (CRIs)-80 to 85-make them virtually indistinguishable from incandescents. The typical 10,0000-hour life of a CFL often makes savings in labor its most desirable feature when compared to a shorter-lived incandescent lamp.

  16. Casimir energy of smooth compact surfaces

    NASA Astrophysics Data System (ADS)

    Straley, Joseph P.; Kolomeisky, Eugene B.

    2014-07-01

    We discuss the formalism of Balian and Duplantier [Balian and Duplantier, Ann. Phys. (NY) 104, 300 (1977), 10.1016/0003-4916(77)90334-7; Balian and Duplantier, Ann. Phys. (NY) 112, 165 (1978), 10.1016/0003-4916(78)90083-0] for the calculation of the Casimir energy for an arbitrary smooth compact surface and use it to give some examples: a finite cylinder with hemispherical caps, a torus, an ellipsoid of revolution, a cube with rounded corners and edges, and a drum made of disks and part of a torus. We propose a model function that approximately captures the shape dependence of the Casimir energy.

  17. Compact memory module for high performance applications

    NASA Astrophysics Data System (ADS)

    Chitty, R.; Capots, L.; Kaschmitter, J.; Tuckerman, D.

    This paper describes a compact large-capacity memory module for high-reliability applications, based on VHSIC hybrid wafer scale integration (HWSI) techology. The HWSI approach features silicon substrates with face-up die attachment and laser-patterned thin-film interconnections between the die and the substrate; this technique offers many advantages over traditional hybrids, such as high-power capability, high-density interconnections, and improved reliability. A specific application of the 64 Megabit SRAM module in a solid state recorder is discussed to illustrate the performance advantage over conventional single-chip and the multichip package technologies.

  18. Raytheon's next generation compact inline cryocooler architecture

    NASA Astrophysics Data System (ADS)

    Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

    2014-01-01

    Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (?25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.

  19. Gamma rays from compact binary system

    E-print Network

    Josep M. Paredes

    2008-10-24

    Some of the very high energy (VHE) gamma-ray sources detected with the modern generation of Cherenkov telescopes have been identified with previously known X-ray binary systems. These detections demonstrate the richness of non-thermal phenomena in compact galactic objects containing relativistic outflows or winds produced near black holes and neutron stars. Recently, the well-known microquasar Cygnus X-3 seems to be associated with a gamma-ray source detected with AGILE. Here I summarise the main observational results on gamma-ray emission from X-ray binaries, as well as some of the proposed scenarios to explain the production of VHE gamma-rays.

  20. An exceptionally bright, compact starburst nucleus

    NASA Technical Reports Server (NTRS)

    Margon, Bruce; Anderson, Scott F.; Mateo, Mario; Fich, Michel; Massey, Philip

    1988-01-01

    Observations are reported of a remarkably bright (V about 13) starburst nucleus, 0833 + 652, which has been detected at radio, infrared, optical, ultraviolet, and X-ray wavelengths. Despite an observed flux at each of these wavelengths which is comparable to that of NGC 7714, often considered the 'prototypical' example of the starburst phenomenon, 0833 + 652 appears to be a previously uncataloged object. Its ease of detectability throughout the electromagnetic spectrum should make it useful for a variety of problems in the study of compact emission-line galaxies.

  1. Panel sees limited interest in compact nukes

    SciTech Connect

    Not Available

    1983-11-01

    Participants in the Joint Power Generation conference thought compact (200- to 300-MW) nuclear reactors would be useful to developing countries, but only the Canadians showed interest in becoming suppliers. Others said they would simply downsize existing designs. A 300-MW mini-Candu that can be built in 48 months will use proven components and have the same price tag as a full-sized unit. A market may develop in the future in the US and other industrialized countries for low-temperature heat sources. Another 5 to 10 developing countries would likely join the 7 now using nuclear power. (DCK)

  2. Compact microlenslet-array-based magnifier.

    PubMed

    Shaoulov, Vesselin; Martins, Ricardo; Rolland, Jannick P

    2004-04-01

    An ultracompact optical imaging system allowing various magnifications or demagnifications and based on microlenslet arrays is presented for the first time to our knowledge. This research generalizes recent findings regarding microlenslet-array-based 1:1 relay systems [Appl. Opt. 42, 6838 (2003)]. Through optical ray tracing, the feasibility of magnifying gray-scale images through a stack of two dissimilar microlenslet arrays is demonstrated for the first time to our knowledge. Results presented specifically demonstrate that a compact imaging system operating at a magnification of 2 is feasible with an overall length of approximately 9 mm. Optical aberrations of the most basic configuration are evaluated, and optimization is discussed. PMID:15072366

  3. Blue compact dwarfs - Extreme dwarf irregular galaxies

    NASA Technical Reports Server (NTRS)

    Thuan, Trinh X.

    1987-01-01

    Observational data on the most extreme members of the irregular dwarf (dI) galaxy class, the blue compact dwarfs (BCDs), are characterized, reviewing the results of recent investigations. The properties of the young stellar population, the ionized gas, the older star population, and the gas and dust of BCDs are contrasted with those of other dIs; BCD morphology is illustrated with sample images; and the value of BCDs (as nearby 'young' chemically unevolved galaxies) for studies of galaxy formation, galactic evolution, and starburst triggering mechanisms is indicated.

  4. Compact proton spectrometers for measurements of shock

    SciTech Connect

    Mackinnon, A; Zylstra, A; Frenje, J A; Seguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M G; Casey, D T; Sinenian, N; Manuel, M; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G; Dewald, E; Doeppner, T; Edwards, M J; Glenzer, S H; Hicks, D; Landen, O L; London, R; Meezan, N B

    2012-05-02

    The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign (NIC) diagnostic. The WRF measures the spectrum of protons from D-{sup 3}He reactions in tuning-campaign implosions containing D and {sup 3}He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total {rho}R through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

  5. Raytheon's next generation compact inline cryocooler architecture

    SciTech Connect

    Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T. [Raytheon Space and Airborne Systems, 2000 E. El Segundo Blvd., El Segundo, CA 90245 (United States)

    2014-01-29

    Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (?25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.

  6. Phase conversion dissipation in multicomponent compact stars

    NASA Astrophysics Data System (ADS)

    Alford, Mark G.; Han, Sophia; Schwenzer, Kai

    2015-05-01

    We propose a mechanism for the damping of density oscillations in multicomponent compact stars. The mechanism is the periodic conversion between different phases, i.e., the movement of the interface between them, induced by pressure oscillations in the star. The damping grows nonlinearly with the amplitude of the oscillation. We study in detail the case of r-modes in a hybrid star with a sharp interface, and we find that this mechanism is powerful enough to saturate the r-mode at very low saturation amplitude, of order 10-10, and is therefore likely to be the dominant r-mode saturation mechanism in hybrid stars with a sharp interface.

  7. A compact simulator for CNI RF environments

    NASA Astrophysics Data System (ADS)

    Blount, Richard; Dankberg, Mark; Nolan, Peter; Thornton, Richard

    The authors describe the architecture, waveform simulation capabilities, and applications of an RF environment simulator capable of simulating up to 1000 simultaneous communication signals operating at frequencies from low HF to microwave. The simulator uses a modulator architecture and an innovative programmable emitter module to simulate a broad range of waveforms, signal structures, and platform dynamics effects in a compact physical size. The purpose of the simulator is to provide a test environment that adequately stresses the increasingly complex electronic warfare and communications, navigation, and identification (CNI) systems found on modern military platforms.

  8. A compact, robust and versatile moiré interferometer

    NASA Astrophysics Data System (ADS)

    Mollenhauer, D. H.; Ifju, P. G.; Han, B.

    A moiré interferometer was designed and constructed based on a general system design using a reflective crossed-line diffraction grating to produce the four beams of light necessary for moiré interferometry. The design concept, basic design and tuning procedures are discussed. The important features of the interferometer, i.e. compactness, versatility, polarization insensitivity, relaxed collimation requirements, low laser power and remote optics, are addressed. Several such interferometers have been constructed and successfully applied to engineering problems. These include examining the displacement fields surrounding drilled and preformed holes in composite laminates loaded in tension, and the evaluation of nonhomogeneous behavior in textile composites.

  9. Plasma immersion ion charge state and mass spectrometer

    SciTech Connect

    Ryabchikov, Alexander I.; Ryabchikov, Igor A.; Stepanov, Igor B.; Sinebryukhov, Andrei A. [Nuclear Physics Institute, 2a Lenin Avenue, Tomsk 634050 (Russian Federation)

    2006-03-15

    This work is devoted to the development and investigation of a new spectrometer for the measurement of ion charge state and mass composition of a plasma based on the combination of two methods--plasma immersion ion acceleration and time-of-flight ion separation. Ion acceleration in the spectrometer is carried out in the short-pulse mode by applying a negative bias potential to the plasma-immersed drift tube. The measurement of the ion current at the end of the tube using time-of-flight ion separation must be done after the bias potential pulse termination. The investigations of the ion charge state were carried out using a dc vacuum-arc Ti metal plasma. It is experimentally shown that the application of a negative bias potential with a pulse amplitude of more than 1.5 kV and duration in the range from 50 to 1000 ns allows measuring the spectra with good charge state and mass resolution for various plasma concentrations and drift tube lengths from 0.5 to 0.9 m. The spectrometer is noted for the design simplicity and compactness. It can be used for ion charge state and mass composition investigation in the wide range of concentration of most Periodic Table metal element plasmas.

  10. Properties of Electrostatic Charge: Interactive Lecture Demonstration

    NSDL National Science Digital Library

    Marsha Hobbs

    This activity is an interactive lecture demonstration format which can be used to teach the first lesson of electrostatics. Students will investigate conservation of charge, charge by contact, polarization of charge and charge by induction.

  11. 24 CFR 2700.210 - Finance charges.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 2012-04-01 false Finance charges. 2700.210 Section 2700.210...PROGRAM Emergency Assistance § 2700.210 Finance charges. The maximum permissible finance charge, exclusive of fees and charges as...

  12. 24 CFR 2700.210 - Finance charges.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 2014-04-01 false Finance charges. 2700.210 Section 2700.210...PROGRAM Emergency Assistance § 2700.210 Finance charges. The maximum permissible finance charge, exclusive of fees and charges as...

  13. 24 CFR 2700.210 - Finance charges.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 2011-04-01 false Finance charges. 2700.210 Section 2700.210...PROGRAM Emergency Assistance § 2700.210 Finance charges. The maximum permissible finance charge, exclusive of fees and charges as...

  14. 24 CFR 2700.210 - Finance charges.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 2013-04-01 false Finance charges. 2700.210 Section 2700.210...PROGRAM Emergency Assistance § 2700.210 Finance charges. The maximum permissible finance charge, exclusive of fees and charges as...

  15. Kondo flow invariants, twisted K-theory and Ramond-Ramond charges

    E-print Network

    Monnier, Samuel

    2008-01-01

    We take a worldsheet point of view on the relation between Ramond-Ramond charges, invariants of boundary renormalization group flows and K-theory. In compact super Wess-Zumino-Witten models, we show how to associate invariants of the generalized Kondo renormalization group flows to a given supersymmetric boundary state. The procedure involved is reminiscent of the way one can probe the Ramond-Ramond charge carried by a D-brane in conformal field theory, and the set of these invariants is isomorphic to the twisted K-theory of the Lie group. We construct various supersymmetric boundary states, and we compute the charges of the corresponding D-branes, disproving two conjectures on this subject. We find a complete agreement between our algebraic charges and the geometry of the D-branes.

  16. Kondo flow invariants, twisted K-theory and Ramond-Ramond charges

    E-print Network

    Samuel Monnier

    2008-07-06

    We take a worldsheet point of view on the relation between Ramond-Ramond charges, invariants of boundary renormalization group flows and K-theory. In compact super Wess-Zumino-Witten models, we show how to associate invariants of the generalized Kondo renormalization group flows to a given supersymmetric boundary state. The procedure involved is reminiscent of the way one can probe the Ramond-Ramond charge carried by a D-brane in conformal field theory, and the set of these invariants is isomorphic to the twisted K-theory of the Lie group. We construct various supersymmetric boundary states, and we compute the charges of the corresponding D-branes, disproving two conjectures on this subject. We find a complete agreement between our algebraic charges and the geometry of the D-branes.

  17. Global Aspects of Charged Particle Motion in Axially Symmetric Multipole Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    2003-01-01

    The motion of a single charged particle in the space outside of a compact region of steady currents is investigated. The charged particle is assumed to produce negligible electromagnetic radiation, so that its energy is conserved. The source of the magnetic field is represented as a point multipole. After a general description, attention is focused on magnetic fields with axial symmetry. Lagrangian dynamical theory is utilized to identify constants of the motion as well as the equations of motion themselves. The qualitative method of Stonner is used to examine charged particle motion in axisymmetric multipole fields of all orders. Although the equations of motion generally have no analytical solutions and must be integrated numerically to produce a specific orbit, a topological examination of dynamics is possible, and can be used, d la Stonner, to completely describe the global aspects of the motion of a single charged particle in a space with an axisymmetric multipole magnetic field.

  18. Numerical prediction of soil compaction in geotechnical engineering

    NASA Astrophysics Data System (ADS)

    Xia, Kaiming

    2014-03-01

    Soil compaction involves a reduction in volume of the soil mass instead of settlement, which has been considered as one of the most important methods to increase geomaterials' strength in geotechnical engineering practice. This paper presents a numerical model to simulate soil compaction using the finite-element method with finite deformation. The fundamental formulations for soil compaction are introduced first. Then the model is employed to simulate the compaction process and predict spatial density, in which the soil is modeled as elastoplastic material. The Drucker-Prager/Cap model is integrated in the large-deformation finite-element code and used to model the gradual compaction process of soil. Representative simulations of practical applications in geotechnical/pavement engineering are provided to demonstrate the feasibility of predicting soil compaction density using the proposed large-deformation finite-element model.

  19. Chromatin Compaction Protects Genomic DNA from Radiation Damage

    PubMed Central

    Takata, Hideaki; Hanafusa, Tomo; Mori, Toshiaki; Shimura, Mari; Iida, Yutaka; Ishikawa, Kenichi; Yoshikawa, Kenichi; Yoshikawa, Yuko; Maeshima, Kazuhiro

    2013-01-01

    Genomic DNA is organized three-dimensionally in the nucleus, and is thought to form compact chromatin domains. Although chromatin compaction is known to be essential for mitosis, whether it confers other advantages, particularly in interphase cells, remains unknown. Here, we report that chromatin compaction protects genomic DNA from radiation damage. Using a newly developed solid-phase system, we found that the frequency of double-strand breaks (DSBs) in compact chromatin after ionizing irradiation was 5–50-fold lower than in decondensed chromatin. Since radical scavengers inhibited DSB induction in decondensed chromatin, condensed chromatin had a lower level of reactive radical generation after ionizing irradiation. We also found that chromatin compaction protects DNA from attack by chemical agents. Our findings suggest that genomic DNA compaction plays an important role in maintaining genomic integrity. PMID:24130727

  20. Compact designer TALENs for efficient genome engineering

    PubMed Central

    Beurdeley, Marine; Bietz, Fabian; Li, Jin; Thomas, Severine; Stoddard, Thomas; Juillerat, Alexandre; Zhang, Feng; Voytas, Daniel F.; Duchateau, Philippe; Silva, George H.

    2013-01-01

    Transcription activator-like effector nucleases are readily targetable ‘molecular scissors’ for genome engineering applications. These artificial nucleases offer high specificity coupled with simplicity in design that results from the ability to serially chain transcription activator-like effector repeat arrays to target individual DNA bases. However, these benefits come at the cost of an appreciably large multimeric protein complex, in which DNA cleavage is governed by the nonspecific FokI nuclease domain. Here we report a significant improvement to the standard transcription activator-like effector nuclease architecture by leveraging the partially specific I-TevI catalytic domain to create a new class of monomeric, DNA-cleaving enzymes. In vivo yeast, plant and mammalian cell assays demonstrate that the half-size, single-polypeptide compact transcription activator-like effector nucleases exhibit overall activity and specificity comparable to currently available designer nucleases. In addition, we harness the catalytic mechanism of I-TevI to generate novel compact transcription activator-like effector nuclease-based nicking enzymes that display a greater than 25-fold increase in relative targeted gene correction efficacy. PMID:23612303