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Sample records for charged polytropic compact

  1. Cracking of general relativistic anisotropic polytropes

    NASA Astrophysics Data System (ADS)

    Herrera, L.; Fuenmayor, E.; León, P.

    2016-01-01

    We discuss the effect that small fluctuations of the local anisotropy of pressure and of the energy density may have on the occurrence of cracking in spherical compact objects, satisfying a polytropic equation of state. Two different kinds of polytropes are considered. For both, it is shown that departures from equilibrium may lead to the appearance of cracking, for a wide range of values of the parameters defining the polytrope. Prospective applications of the obtained results to some astrophysical scenarios are pointed out.

  2. Spherical polytropic balls cannot mimic black holes

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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 the 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 as black holes, and detection of a shadow image cannot be direct evidence of black hole existence. This paper examines whether or not such compact objects can exist under some suitable conditions. We investigate thoroughly the static spherical polytropic ball of perfect fluid with single polytrope index, and then investigate a representative example of a piecewise polytropic ball. Our result is that the spherical polytropic ball which we have investigated cannot possess UCOP, if the speed of sound at the center is subluminal (slower than light). This means that, if the polytrope treated in this paper is a good model of stellar matter in compact objects, the detection of a shadow image can be regarded as good evidence of black hole existence. As a by-product, we have found the upper bound of the mass-to-radius ratio of a polytropic ball with single index, M_{ast }/R_{ast } < 0.281, under the condition of subluminal sound speed.

  3. New results on charged compact boson stars

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Kulshreshtha, Usha; Kulshreshtha, Daya Shankar

    2016-05-01

    In this work we present some new results that we have obtained in a study of the phase diagram of charged compact boson stars in the theory involving massive complex scalar fields coupled to the U(1) gauge field and gravity in a conical potential in the presence of a cosmological constant Λ , which we treat as a free parameter taking positive and negative values and thereby allowing us to study the theory in de Sitter and anti de Sitter spaces, respectively. We obtain four bifurcation points (the possibility of more bifurcation points not being ruled out) in the de Sitter region. We present a detailed discussion of the various regions in our phase diagram with respect to four bifurcation points. Our theory is seen to have rich physics in a particular domain for positive values of Λ , which is consistent with the accelerated expansion of the Universe.

  4. Flying through polytropes

    NASA Astrophysics Data System (ADS)

    Pesnell, W. Dean

    2016-03-01

    Dropping objects into a tunnel bored through Earth has been used to visualize simple harmonic motion for many years, and even imagined for use as rapid transport systems. Unlike previous studies that assumed a constant density Earth, here we calculate the fall-through time of polytropes, models of Earth's interior where the pressure varies as a power of the density. This means the fall-through time can be calculated as the central condensation varies from one to large within the family of polytropes. Having a family of models, rather than a single model, helps to explore the properties of planets and stars. Comparing the family of phase space solutions shows that the fall-through time and velocity approach the limit of radial free-fall onto a point mass as the central condensation increases. More condensed models give higher maximum velocities but do not have the right global properties for Earth. The angular distance one can travel along the surface is calculated as a brachistochrone (path of least time) tunnel that is a function of the depth to which the tunnel is bored. We also show that completely degenerate objects, simple models of white dwarf stars supported by completely degenerate electrons, have sizes similar to Earth but their much higher masses mean a much larger gravitational strength and a shorter fall-through time. Numerical integrations of the equations describing polytropes and completely degenerate objects are used to generate the initial models. Analytic solutions and numerical integration of the equations of motion are used to calculate the fall-through time for each model, and numerical integrations with analytic approximations at the boundaries are used to calculate the brachistochrones in the polytropes. Scaling relationships are provided to help use these results in other planets and stars.

  5. A new model for charged anisotropic compact star

    NASA Astrophysics Data System (ADS)

    Maurya, S. K.; Jasim, M. K.; Gupta, Y. K.; Smitha, T. T.

    2016-05-01

    In this paper, we have obtained a new singularity free charged anisotropic fluid solution of Einstein's field equations. The physical parameters as radial pressure, tangential pressure, energy density, charge density, electric field intensity, velocity of sound and red-shift are well behaved everywhere inside the star. The obtained compact star models can represent the observational compact objects as PSR 1937{+}21 and PSR J1614-2230.

  6. Stability of polytropes

    SciTech Connect

    Froensdal, Christian

    2008-05-15

    This paper is an investigation of the stability of some ideal stars. It is intended as a study in general relativity, with emphasis on the coupling to matter, aimed at a better understanding of strong gravitational fields and 'black holes'. This contrasts with the usual attitude in astrophysics, where Einstein's equations are invoked as a refinement of classical thermodynamics and Newtonian gravity. Our work is based on action principles for systems of metric and matter fields, well-defined relativistic field models that we hope may represent plausible types of matter. The thermodynamic content must be extracted from the theory itself. When the flow of matter is irrotational, and described by a scalar density, we are led to differential equations that differ little from those of Tolman, but they admit a conserved current, and stronger boundary conditions that affect the matching of the interior solution to an external metric and imply a relation of mass and radius. We propose a complete revision of the treatment of boundary conditions. An ideal star in our terminology has spherical symmetry and an isentropic equation of state, p=a{rho}{sup {gamma}}, a and {gamma} piecewise constant. In our first work it was assumed that the density vanished beyond a finite distance from the origin and that the metric is to be matched at the boundary to an exterior Schwartzchild metric. But it is difficult to decide what the boundary conditions should be and we are consequently skeptical of the concept of a fixed boundary. We investigate the double polytrope, characterized by a polytropic index n{<=}3, in the bulk of the star and a value larger than five in an outer atmosphere that extends to infinity. It has no fixed boundary but a region of critical density where the polytropic index changes from a value that is appropriate for the bulk of the star to a value that provides a crude model for the atmosphere. The boundary conditions are now natural and unambiguous. The existence of a relation between mass and radius is confirmed, as well as an upper limit on the mass. The principal conclusion is that all the static configurations are stable. There is a solution that fits the Sun. The masses of white dwarfs respect the Chandrasekhar limit. The application to neutron stars has surprising aspects.

  7. A compact source for bunches of singly charged atomic ions

    NASA Astrophysics Data System (ADS)

    Murböck, T.; Schmidt, S.; Andelkovic, Z.; Birkl, G.; Nörtershäuser, W.; Vogel, M.

    2016-04-01

    We have built, operated, and characterized a compact ion source for low-energy bunches of singly charged atomic ions in a vacuum beam line. It is based on atomic evaporation from an electrically heated oven and ionization by electron impact from a heated filament inside a grid-based ionization volume. An adjacent electrode arrangement is used for ion extraction and focusing by applying positive high-voltage pulses to the grid. The method is particularly suited for experimental environments which require low electromagnetic noise. It has proven simple yet reliable and has been used to produce μs-bunches of up to 106 Mg+ ions at a repetition rate of 1 Hz. We present the concept, setup and characterizing measurements. The instrument has been operated in the framework of the SpecTrap experiment at the HITRAP facility at GSI/FAIR to provide Mg+ ions for sympathetic cooling of highly charged ions by laser-cooled 24Mg+.

  8. Relativistic Solution for a Class of Static Compact Charged Star in Pseudo-Spheroidal Spacetime

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Pradip Kumar; Deb, Rumi; Paul, Bikash Chandra

    2012-08-01

    Considering Vaidya-Tikekar metric, we obtain a class of solutions of the Einstein-Maxwell equations for a charged static fluid sphere. The physical 3-space (t = const.) here is described by pseudo-spheroidal geometry. The relativistic solution for the theory is used to obtain models for charged compact objects; thereafter, a qualitative analysis of the physical aspects of compact objects are studied. The dependence of some of the properties of a superdense star on the parameters of the three geometry is explored. We note that the spheroidicity parameter a plays an important role for determining the properties of a compact object. A nonlinear equation of state (EOS) is required to describe a charged compact object with pseudo-spheroidal geometry, which we have shown for known masses of compact objects. We also note that the size of a static compact charged star is more than that of a static compact star without charge.

  9. A compact source for bunches of singly charged atomic ions.

    PubMed

    Murböck, T; Schmidt, S; Andelkovic, Z; Birkl, G; Nörtershäuser, W; Vogel, M

    2016-04-01

    We have built, operated, and characterized a compact ion source for low-energy bunches of singly charged atomic ions in a vacuum beam line. It is based on atomic evaporation from an electrically heated oven and ionization by electron impact from a heated filament inside a grid-based ionization volume. An adjacent electrode arrangement is used for ion extraction and focusing by applying positive high-voltage pulses to the grid. The method is particularly suited for experimental environments which require low electromagnetic noise. It has proven simple yet reliable and has been used to produce μs-bunches of up to 10(6) Mg(+) ions at a repetition rate of 1 Hz. We present the concept, setup and characterizing measurements. The instrument has been operated in the framework of the SpecTrap experiment at the HITRAP facility at GSI/FAIR to provide Mg(+) ions for sympathetic cooling of highly charged ions by laser-cooled (24)Mg(+). PMID:27131666

  10. Polytropic black hole as a heat engine

    NASA Astrophysics Data System (ADS)

    Setare, M. R.; Adami, H.

    2015-11-01

    Recently we have found an asymptotically AdS solution for Einstein's equations, those of thermodynamics match those of a special case of polytropic gas (Setare and Adami in Phys Rev D 91:084014, 2015). Here we show that a polytropic black hole can be considered as a heat engine and then we calculate work done by this system and its efficiency.

  11. Conformally flat polytropes for anisotropic matter

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  12. Superposition of Polytropes in the Inner Heliosheath

    NASA Astrophysics Data System (ADS)

    Livadiotis, G.

    2016-03-01

    This paper presents a possible generalization of the equation of state and Bernoulli's integral when a superposition of polytropic processes applies in space and astrophysical plasmas. The theory of polytropic thermodynamic processes for a fixed polytropic index is extended for a superposition of polytropic indices. In general, the superposition may be described by any distribution of polytropic indices, but emphasis is placed on a Gaussian distribution. The polytropic density-temperature relation has been used in numerous analyses of space plasma data. This linear relation on a log-log scale is now generalized to a concave-downward parabola that is able to describe the observations better. The model of the Gaussian superposition of polytropes is successfully applied in the proton plasma of the inner heliosheath. The estimated mean polytropic index is near zero, indicating the dominance of isobaric thermodynamic processes in the sheath, similar to other previously published analyses. By computing Bernoulli's integral and applying its conservation along the equator of the inner heliosheath, the magnetic field in the inner heliosheath is estimated, B ˜ 2.29 ± 0.16 μG. The constructed normalized histogram of the values of the magnetic field is similar to that derived from a different method that uses the concept of large-scale quantization, bringing incredible insights to this novel theory.

  13. The characteristics of polytropic magnetic refrigeration cycles

    SciTech Connect

    Yan, Z.; Chen, J. , P.O. Box 8730, Beijing 100080 Department of Physics, Xiamen University, Xiamen, Fujian )

    1991-08-15

    The concepts of generalized polytropic processes and polytropic refrigeration cycles, which consist of two isothermal processes and two generalized polytropic processes of paramagnetic salt, are introduced. It is shown that such a class of general magnetic refrigeration cycles, which includes the Carnot, Stirling, and other useful magnetic refrigeration cycles, possesses the conditions of perfect regeneration and can have the same coefficient of performance as the Carnot cycle for the same temperature range. Thus, they have many applications in the research and manufacture of magnetic refrigerators.

  14. Visible transitions of highly charged tungsten ions observed with a compact electron beam ion trap

    NASA Astrophysics Data System (ADS)

    Minoshima, Maki; Sakoda, Junpei; Komatsu, Akihiro; Sakaue, Hiroyuki A.; Ding, Xiao-Bin; Kato, Daiji; Murakami, Izumi; Dong, Chen-Zhong; Koike, Fumihiro; Watanabe, Hirofumi; Nakamura, Nobuyuki

    2013-09-01

    We present visible spectra of highly charged tungsten ions observed with a compact electron beam ion trap (EBIT). Several transition lines previously observed with the Tokyo EBIT (Watanabe et al 2012 Can. J. Phys. 90 497) have been reproducibly observed. By observing the electron energy dependence in detail, the charge state of the ion responsible for those lines is identified.

  15. A Compact Wireless Charging System for Electric Vehicles

    SciTech Connect

    Ning, Puqi; Miller, John M; Onar, Omer C; White, Cliff P

    2013-01-01

    In this paper, a compact high efficiency wireless power transfer system has been designed and developed. The detailed gate drive design, cooling system design, power stage development, and system assembling are presented. The successful tests verified the feasibility of wireless power transfer system to achieve over-all 90% efficiency.

  16. Quasinormal modes of the polytropic hydrodynamic vortex

    NASA Astrophysics Data System (ADS)

    Oliveira, Leandro A.; Cardoso, Vitor; Crispino, Luís C. B.

    2015-07-01

    Analogue systems are a powerful instrument to investigate and understand in a controlled setting many general-relativistic effects. Here, we focus on superradiant-triggered instabilities and quasinormal modes. We consider a compressible hydrodynamic vortex characterized by a polytropic equation of state, the polytropic hydrodynamic vortex, a purely circulating system with an ergoregion but no event horizon. We compute the quasinormal modes of this system numerically with different methods, finding excellent agreement between them. When the fluid velocity is larger than the speed of sound, an ergoregion appears in the effective spacetime, triggering an "ergoregion instability." We study the details of the instability for the polytropic vortex, and in particular find analytic expressions for the marginally stable configuration.

  17. Magnetic flux concentrations in a polytropic atmosphere

    NASA Astrophysics Data System (ADS)

    Losada, I. R.; Brandenburg, A.; Kleeorin, N.; Rogachevskii, I.

    2014-04-01

    Context. Strongly stratified hydromagnetic turbulence has recently been identified as a candidate for explaining the spontaneous formation of magnetic flux concentrations by the negative effective magnetic pressure instability (NEMPI). Much of this work has been done for isothermal layers, in which the density scale height is constant throughout. Aims: We now want to know whether earlier conclusions regarding the size of magnetic structures and their growth rates carry over to the case of polytropic layers, in which the scale height decreases sharply as one approaches the surface. Methods: To allow for a continuous transition from isothermal to polytropic layers, we employ a generalization of the exponential function known as the q-exponential. This implies that the top of the polytropic layer shifts with changing polytropic index such that the scale height is always the same at some reference height. We used both mean-field simulations (MFS) and direct numerical simulations (DNS) of forced stratified turbulence to determine the resulting flux concentrations in polytropic layers. Cases of both horizontal and vertical applied magnetic fields were considered. Results: Magnetic structures begin to form at a depth where the magnetic field strength is a small fraction of the local equipartition field strength with respect to the turbulent kinetic energy. Unlike the isothermal case where stronger fields can give rise to magnetic flux concentrations at larger depths, in the polytropic case the growth rate of NEMPI decreases for structures deeper down. Moreover, the structures that form higher up have a smaller horizontal scale of about four times their local depth. For vertical fields, magnetic structures of super-equipartition strengths are formed, because such fields survive downward advection that causes NEMPI with horizontal magnetic fields to reach premature nonlinear saturation by what is called the "potato-sack" effect. The horizontal cross-section of such structures found in DNS is approximately circular, which is reproduced with MFS of NEMPI using a vertical magnetic field. Conclusions: Results based on isothermal models can be applied locally to polytropic layers. For vertical fields, magnetic flux concentrations of super-equipartition strengths form, which supports suggestions that sunspot formation might be a shallow phenomenon.

  18. Compact electron beam ion trap for spectroscopy of moderate charge state ions.

    PubMed

    Nakamura, Nobuyuki; Kikuchi, Hiroyuki; Sakaue, Hiroyuki A; Watanabe, Tetsuya

    2008-06-01

    A compact electron beam ion trap (EBIT) has been constructed for spectroscopic studies of moderate charge state ions. The electron beam energy range of the present EBIT is 100-1000 eV, for which it is rather difficult to operate an ordinary EBIT which used to be designed for operation with higher electron energy (~10 keV or more). To cut down the running costs, a superconducting wire with a high critical temperature is used for the central magnet so that it can be operated without liquid helium. The performance of the compact EBIT has been investigated through visible spectroscopy of highly charged krypton and iron ions. PMID:18601394

  19. 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.

  20. Non-linear effects on radiation propagation around a charged compact object

    NASA Astrophysics Data System (ADS)

    Cuzinatto, R. R.; de Melo, C. A. M.; de Vasconcelos, K. C.; Medeiros, L. G.; Pompeia, P. J.

    2015-10-01

    The propagation of non-linear electromagnetic waves is carefully analyzed on a curved spacetime created by static spherically symmetric mass and charge distribution. We compute how non-linear electrodynamics affects the geodesic deviation and the redshift of photons propagating near this massive charged object. In the first order approximation, the effects of electromagnetic self-interaction can be distinguished from the usual Reissner-Nordström terms. In the particular case of Euler-Heisenberg effective Lagrangian, we find that these self-interaction effects might be important near extremal compact charged objects.

  1. A compact, high-voltage pulsed charging system based on an air-core pulse transformer.

    PubMed

    Zhang, Tianyang; Chen, Dongqun; Liu, Jinliang; Liu, Chebo; Yin, Yi

    2015-09-01

    Charging systems of pulsed power generators on mobile platforms are expected to be compact and provide high pulsed power, high voltage output, and high repetition rate. In this paper, a high-voltage pulsed charging system with the aforementioned characteristics is introduced, which can be applied to charge a high-voltage load capacitor. The operating principle of the system and the technical details of the components in the system are described in this paper. The experimental results show that a 600 nF load capacitor can be charged to 60 kV at 10 Hz by the high-voltage pulsed charging system for a burst of 0.5 s. The weight and volume of the system are 60 kg and 600 × 500 × 380 mm(3), respectively. PMID:26429466

  2. Attenuation of DNA charge transport by compaction into a nucleosome core particle

    PubMed Central

    Bjorklund, Chad C.; Davis, William B.

    2006-01-01

    The nucleosome core particle (NCP) is the fundamental building block of chromatin which compacts ∼146 bp of DNA around a core histone protein octamer. The effects of NCP packaging on long-range DNA charge transport reactions have not been adequately assessed to date. Here we study DNA hole transport reactions in a 157 bp DNA duplex (AQ-157TG) incorporating multiple repeats of the DNA TG-motif, a strong NCP positioning sequence and a covalently attached Anthraquinone photooxidant. Following a thorough biophysical characterization of the structure of AQ-157TG NCPs by Exonuclease III and hydroxyl radical footprinting, we compared the dynamics of DNA charge transport in ultraviolet-irradiated free and NCP-incorporated AQ-157TG. Compaction into a NCP changes the charge transport dynamics in AQ-157TG drastically. Not only is the overall yield of oxidative lesions decreased in the NCPs, but the preferred sites of oxidative damage change as well. This NCP-dependent attenuation of DNA charge transport is attributed to DNA–protein interactions involving the folded histone core since removal of the histone tails did not perturb the charge transport dynamics in AQ-157TG NCPs. PMID:16595797

  3. Polytropic dark haloes of elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Saxton, Curtis J.; Ferreras, Ignacio

    2010-06-01

    The kinematics of stars and planetary nebulae in early-type galaxies provide vital clues to the enigmatic physics of their dark matter haloes. We fit published data for 14 such galaxies using a spherical, self-gravitating model with two components: (i) a Srsic stellar profile fixed according to photometric parameters, and (ii) a polytropic dark matter halo that conforms consistently to the shared gravitational potential. The polytropic equation of state can describe extended theories of dark matter involving self-interaction, non-extensive thermostatistics or boson condensation (in a classical limit). In such models, the flat-cored mass profiles widely observed in disc galaxies are due to innate dark physics, regardless of any baryonic agitation. One of the natural parameters of this scenario is the number of effective thermal degrees of freedom of dark matter (Fd) which is proportional to the dark heat capacity. By default, we assume a cosmic ratio of baryonic and dark mass. Non-Srsic kinematic ideosyncrasies and possible non-sphericity thwart fitting in some cases. In all 14 galaxies, the fit with a polytropic dark halo improves or at least gives similar fits to the velocity dispersion profile, compared to a stars-only model. The good halo fits usually prefer Fd values from six to eight. This range complements the recently inferred limit of 7 < Fd < 10, derived from constraints on galaxy cluster core radii and black hole masses. However, a degeneracy remains: radial orbital anisotropy or a depleted dark mass fraction could shift our models' preference towards lower Fd; whereas a loss of baryons would favour higher Fd.

  4. 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).

  5. 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 - γ for the self-similar index n and the polytropic index γ to a general relation n = 2(q + γ - 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 γ > 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 ≤ γ ≤ 1.50 and 0.99 ≤ n ≤ 1.0. The GP-LPH solutions with 0.94 < n < 0.99 and 1.47 < γ < 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.

  6. A variable polytrope index applied to planet and material models

    NASA Astrophysics Data System (ADS)

    Thielen, Kevin; Weppner, Stephen; Zielinski, Alexander

    2016-01-01

    We introduce a new approach to a century-old assumption which enhances not only planetary interior calculations but also high-pressure material physics. We show that the polytropic index is the derivative of the bulk modulus with respect to pressure. We then augment the traditional polytrope theory by including a variable polytrope index within the confines of the Lane-Emden differential equation. To investigate the possibilities of this method, we create a high-quality universal equation of state, transforming the traditional polytrope method to a tool with the potential for excellent predictive power. The theoretical foundation of our equation of state is the same elastic observable which we found equivalent to the polytrope index, the derivative of the bulk modulus with respect to pressure. We calculate the density-pressure of six common materials up to 1018 Pa, mass-radius relationships for the same materials, and produce plausible density-radius models for the rocky planets of our Solar system. We argue that the bulk modulus and its derivatives have been underutilized in previous planet formation methods. We constrain the material surface observables for the inner core, outer core, and mantle of planet Earth in a systematic way including pressure, bulk modulus, and the polytrope index in the analysis. We believe that this variable polytrope method has the necessary apparatus to be extended further to gas giants and stars. As supplemental material we provide computer code to calculate multi-layered planets.

  7. A variable polytrope index applied to planet and material models

    NASA Astrophysics Data System (ADS)

    Weppner, S. P.; McKelvey, J. P.; Thielen, K. D.; Zielinski, A. K.

    2015-09-01

    We introduce a new approach to a century-old assumption which enhances not only planetary interior calculations but also high-pressure material physics. We show that the polytropic index is the derivative of the bulk modulus with respect to pressure. We then augment the traditional polytrope theory by including a variable polytrope index within the confines of the Lane-Emden differential equation. To investigate the possibilities of this method, we create a high-quality universal equation of state, transforming the traditional polytrope method to a tool with the potential for excellent predictive power. The theoretical foundation of our equation of state is the same elastic observable which we found equivalent to the polytrope index, the derivative of the bulk modulus with respect to pressure. We calculate the density-pressure of six common materials up to 1018 Pa, mass-radius relationships for the same materials, and produce plausible density-radius models for the rocky planets of our Solar system. We argue that the bulk modulus and its derivatives have been underutilized in previous planet formation methods. We constrain the material surface observables for the inner core, outer core, and mantle of planet Earth in a systematic way including pressure, bulk modulus, and the polytrope index in the analysis. We believe that this variable polytrope method has the necessary apparatus to be extended further to gas giants and stars. As supplemental material we provide computer code to calculate multi-layered planets.

  8. A compact time-resolving pepperpot emittance meter for low-energy highly charged ions

    NASA Astrophysics Data System (ADS)

    Hobein, M.; Liu, Y.; Solders, A.; Suhonen, M.; Kamalou, O.; Schuch, R.

    2011-06-01

    An emittance meter for pulsed, low-energy ion beams was developed. Based on the pepperpot method, the device is compact and portable. It has been installed at the S-EBIT Laboratory at AlbaNova, Stockholm University, to measure the emittance of highly charged ions extracted from the electron beam ion trap R-EBIT and the cooling trap of the high-precision Penning trap mass spectrometer SMILETRAP II. Using a fast delay-line anode detector, the emittance and time-of-flight of the extracted ions can be measured simultaneously. In this paper, design and data processing system are described and preliminary results are presented.

  9. Rapidly rotating polytropes in general relativity

    NASA Technical Reports Server (NTRS)

    Cook, Gregory B.; Shapiro, Stuart L.; Teukolsky, Saul A.

    1994-01-01

    We construct an extensive set of equilibrium sequences of rotating polytropes in general relativity. We determine a number of important physical parameters of such stars, including maximum mass and maximum spin rate. The stability of the configurations against quasi-radial perturbations is diagnosed. Two classes of evolutionary sequences of fixed rest mass and entropy are explored: normal sequences which behave very much like Newtonian evolutionary sequences, and supramassive sequences which exist solely because of relativistic effects. Dissipation leading to loss of angular momentum causes a star to evolve in a quasi-stationary fashion along an evolutionary sequence. Supramassive sequences evolve towards eventual catastrophic collapse to a black hole. Prior to collapse, the star must spin up as it loses angular momentum, an effect which may provide an observational precursor to gravitational collapse to a black hole.

  10. Development of compact rapid charging power supply for capacitive energy storage in pulsed power drivers

    NASA Astrophysics Data System (ADS)

    Sharma, Surender Kumar; Shyam, Anurag

    2015-02-01

    High energy capacitor bank is used for primary electrical energy storage in pulsed power drivers. The capacitors used in these pulsed power drivers have low inductance, low internal resistance, and less dc life, so it has to be charged rapidly and immediately discharged into the load. A series resonant converter based 45 kV compact power supply is designed and developed for rapid charging of the capacitor bank with constant charging current up to 150 mA. It is short circuit proof, and zero current switching technique is used to commute the semiconductor switch. A high frequency resonant inverter switching at 10 kHz makes the overall size small and reduces the switching losses. The output current of the power supply is limited by constant on-time and variable frequency switching control technique. The power supply is tested by charging the 45 kV/1.67 ?F and 15 kV/356 ?F capacitor banks. It has charged the capacitor bank up to rated voltage with maximum charging current of 150 mA and the average charging rate of 3.4 kJ/s. The output current of the power supply is limited by reducing the switching frequency at 5 kHz, 3.3 kHz, and 1.7 kHz and tested with 45 kV/1.67 ?F capacitor bank. The protection circuit is included in the power supply for over current, under voltage, and over temperature. The design details and the experimental testing results of the power supply for resonant current, output current, and voltage traces of the power supply with capacitive, resistive, and short circuited load are presented and discussed.

  11. Development of compact rapid charging power supply for capacitive energy storage in pulsed power drivers.

    PubMed

    Sharma, Surender Kumar; Shyam, Anurag

    2015-02-01

    High energy capacitor bank is used for primary electrical energy storage in pulsed power drivers. The capacitors used in these pulsed power drivers have low inductance, low internal resistance, and less dc life, so it has to be charged rapidly and immediately discharged into the load. A series resonant converter based 45 kV compact power supply is designed and developed for rapid charging of the capacitor bank with constant charging current up to 150 mA. It is short circuit proof, and zero current switching technique is used to commute the semiconductor switch. A high frequency resonant inverter switching at 10 kHz makes the overall size small and reduces the switching losses. The output current of the power supply is limited by constant on-time and variable frequency switching control technique. The power supply is tested by charging the 45 kV/1.67 μF and 15 kV/356 μF capacitor banks. It has charged the capacitor bank up to rated voltage with maximum charging current of 150 mA and the average charging rate of 3.4 kJ/s. The output current of the power supply is limited by reducing the switching frequency at 5 kHz, 3.3 kHz, and 1.7 kHz and tested with 45 kV/1.67 μF capacitor bank. The protection circuit is included in the power supply for over current, under voltage, and over temperature. The design details and the experimental testing results of the power supply for resonant current, output current, and voltage traces of the power supply with capacitive, resistive, and short circuited load are presented and discussed. PMID:25725838

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

    SciTech Connect

    Madsen, Jes

    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.

  13. A new class of solutions of compact stars with charged distributions on pseudo-spheroidal spacetime

    NASA Astrophysics Data System (ADS)

    Thomas, V. O.; Pandya, D. M.

    2015-12-01

    In this paper a new class of exact solutions of Einstein's field equations for compact stars with charged distributions is obtained on the basis of pseudo-spheroidal spacetime characterized by the metric potential g_{rr}=1+K{r2/R2}/{1+r2/R2}, where K and R are geometric parameters of the spacetime. The expressions for radial pressure (pr) and electric field intensity (E) are chosen in such a way that the model falls in the category of physically acceptable one. The bounds of geometric parameter K and the physical parameters p0 and α are obtained by imposing the physical requirements and regularity conditions. The present model is in good agreement with the observational data of various compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, SMC X-4, Cen X-3 given by Gangopadhyay et al. (Mon. Not. R. Astron. Soc. 431:3216, 2013). When α = 0, the model reduces to the uncharged anisotropic distribution given by Thomas and Pandya (arXiv:1506.08698v1 [gr-qc], 2015).

  14. 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.

  15. The structure of the tidally and rotationally distorted polytropes

    NASA Astrophysics Data System (ADS)

    Singh, M.; Singh, G.

    1983-10-01

    It is noted that Chandrasekhar (1933), in his pioneer work on the tidally and rotationally distorted polytropes, assumed the ratio of the mean radii of the components to their distance apart to be so small that quantities of the sixth-order in the ratio could be neglected. On this assumption, he considered one of the configurations of the system as a mass point. The perturbation method of Chandrasekhar, however, fails near the surface of a polytrope. With this failure in mind, Naylor and Anand (1970) calculated these models using the method of Monaghan and Roxburgh (1965) at the interfacial points chosen by Monaghan and Roxburgh. The models are recalculated here for the polytropic index n = 1.5, 2.0, and 3.0 at new interfacial points to ensure more accurate results. In addition, the structure of these models is studied in more detail for different values of q.

  16. A compact Charged-Particle Spectrometer for OMEGA and the NIF

    NASA Astrophysics Data System (ADS)

    Orozco, D.; Rosenberg, M. J.; Seguin, F. H.; Gatu Johnson, M.; Sio, H.; Zylstra, A. B.; Rinderknecht, H. G.; Rojas, J. A.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.; Glebov, V. Yu,

    2015-11-01

    A very compact scattering pinhole diagnostic (SPD) has been implemented and used to measure the mean energy of charged particles produced in Inertial Confinement (ICF) experiments. This was done by measuring the spatial distribution of mono-energetic particles that passed through a small pinhole, scattered in a thin foil that was positioned about a centimeter in front of a CR-39 detector. To determine the mean energy from the spatial distribution of the scattered particles on the CR-39, an empirical relationship between the scattering angle and the incoming particle energy for a given foil was determined using simulations. Two methods for the energy determination are discussed in this presentation. The capabilities of this diagnostic are demonstrated with DD proton and D3He alpha data from the OMEGA laser. To check the fidelity of the SPD measurements, the results are contrasted to data obtained with other well-established techniques. This work was supported in part by NLUF, US DOE, and LLE.

  17. A varying polytropic gas universe and phase space analysis

    NASA Astrophysics Data System (ADS)

    Khurshudyan, M.

    2016-05-01

    In this paper, we will consider a phenomenological model of a dark fluid that is able to explain an accelerated expansion of our low redshift universe and the phase transition to this accelerated expanding universe. Recent developments in modern cosmology towards understanding of the accelerated expansion of the large scale universe involve various scenarios and approaches. Among these approaches, one of well-known and accepted practice is modeling of the content of our universe via dark fluid. There are various models of dark energy fluid actively studied in recent literature and polytropic gas is among them. In this work, we will consider a varying polytropic gas which is a phenomenological modification of polytropic gas. Our model of varying polytropic dark fluid has been constructed to analogue to a varying Chaplygin gas actively discussed in the literature. We will consider interacting models, where dark matter is a pressureless fluid, to have a comprehensive picture. Phase space analysis is an elegant mathematical tool to earn general understanding of large scale universe and easily see an existence of a solution to cosmological coincidence problem. Imposing some constraints on parameters of the models, we found late time attractors for each case analytically. Cosmological consequences for the obtained late time attractors are discussed.

  18. A compact T-shaped nanodevice for charge sensing of a tunable double quantum dot in scalable silicon technology

    NASA Astrophysics Data System (ADS)

    Tagliaferri, M. L. V.; Crippa, A.; De Michielis, M.; Mazzeo, G.; Fanciulli, M.; Prati, E.

    2016-03-01

    We report on the fabrication and the characterization of a tunable complementary-metal oxide semiconductor (CMOS) system consisting of two quantum dots and a MOS single electron transistor (MOSSET) charge sensor. By exploiting a compact T-shaped design and few gates fabricated by electron beam lithography, the MOSSET senses the charge state of either a single or double quantum dot at 4.2 K. The CMOS compatible fabrication process, the simplified control over the number of quantum dots and the scalable geometry make such architecture exploitable for large scale fabrication of multiple spin-based qubits in circuital quantum information processing.

  19. 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.

  20. Polytropic dark matter flows illuminate dark energy and accelerated expansion

    NASA Astrophysics Data System (ADS)

    Kleidis, K.; Spyrou, N. K.

    2015-04-01

    Currently, a large amount of data implies that the matter constituents of the cosmological dark sector might be collisional. An attractive feature of such a possibility is that, it can reconcile dark matter (DM) and dark energy (DE) in terms of a single component, accommodated in the context of a polytropic-DM fluid. In fact, polytropic processes in a DM fluid have been most successfully used in modeling dark galactic haloes, thus significantly improving the velocity dispersion profiles of galaxies. Motivated by such results, we explore the time evolution and the dynamical characteristics of a spatially-flat cosmological model, in which, in principle, there is no DE at all. Instead, in this model, the DM itself possesses some sort of fluidlike properties, i.e., the fundamental units of the Universe matter-energy content are the volume elements of a DM fluid, performing polytropic flows. In this case, together with all the other physical characteristics, we also take the energy of this fluid's internal motions into account as a source of the universal gravitational field. This form of energy can compensate for the extra energy, needed to compromise spatial flatness, namely, to justify that, today, the total energy density parameter is exactly unity. The polytropic cosmological model, depends on only one free parameter, the corresponding (polytropic) exponent, Γ. We find this model particularly interesting, because for Γ ≤ 0.541, without the need for either any exotic DE or the cosmological constant, the conventional pressure becomes negative enough so that the Universe accelerates its expansion at cosmological redshifts below a transition value. In fact, several physical reasons, e.g., the cosmological requirement for cold DM (CDM) and a positive velocity-of-sound square, impose further constraints on the value of Γ, which is eventually settled down to the range -0.089 < Γ ≤ 0. This cosmological model does not suffer either from the age problem or from the coincidence problem. At the same time, this model reproduces to high accuracy the distance measurements performed with the aid of the supernovae (SNe) Type Ia standard candles, and most naturally interprets, not only when, but also why the Universe transits from deceleration to acceleration, thus arising as a mighty contestant for a DE model.

  1. 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.; Thorn, A.; Zschornack, G.

    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.

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

    PubMed

    Vorobjev, G; Sokolov, A; Thorn, A; Herfurth, F; Kester, O; Quint, W; Stöhlker, Th; Zschornack, G

    2012-05-01

    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(19+) were reached after about a 3 s breeding time. The capture and breeding efficiencies up to 0.016(4)% for K(17+) have been measured. PMID:22667612

  3. 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.

  4. Polytropic index of central plasma sheet ions based on MHD Bernoulli integral

    NASA Astrophysics Data System (ADS)

    Pang, Xuexia; Cao, Jinbin; Liu, Wenlong; Ma, Yuduan; Lu, Haoyu; Yang, Junying; Li, Liuyuan; Liu, Xu; Wang, Jing; Wang, Tieyan; Yu, Jiang

    2015-06-01

    This paper uses the data of Cluster from 2001 to 2009 to study the polytropic processes of central plasma sheet (CPS) ions. We first adopt the approach of MHD Bernoulli integral (MBI) to identify homogeneous streamflow tubes (quasi-invariant MBI regions) and then calculate the polytropic index of ions for those streamflow tubes whose outward electromagnetic energy ratios δ < 0.05. The central plasma sheet is actually a complicated system, which comprises many streamflow tubes with different polytropic relations and the transition layers in between. The polytropic indexes of the CPS ions range from 0.1 to 1.8 and have a quasi-Gaussian distribution. The median polytropic index is 0.93 for AE < 200 nT and 0.91 for AE ≥ 200 nT. Thus, there is no obvious difference between the polytropic indexes of the quiet time and the substorm time CPS ions, which suggests that the thinning and thickening processes of plasma sheet during substorm times do not change obviously the polytropic relation of the CPS ions. The statistical analysis using different δ (δ < 0.05, 0.025, and 0.01) shows that the outward emission of electromagnetic energy is an effective cooling mechanism and can make the polytropic index to decrease and shift toward isobaric. It is inferred that the CPS ions as a whole much likely behave in a way between isobaric and isothermal.

  5. Optimization of a compact multicusp He{sup +} ion source for double-charge-exchanged He{sup -} beam

    SciTech Connect

    Shinto, K.; Sugawara, H.; Takenaga, M.; Takeuchi, S.; Tanaka, N.; Okamoto, A.; Kitajima, S.; Sasao, M.; Nishiura, M.; Wada, M.

    2006-03-15

    Preliminary test bench results to study the beam quality extracted from a compact multicusp He{sup +} ion source for He{sup -} beam production are reported. The bench is a part of the beam diagnostic system equipped with energy analyzers, emittance meters, focusing beam optics, an alkali-metal charge-exchange cell, a neutral particle energy analyzer, a double focusing magnetic momentum analyzer, a postaccelerator, and a drift tube. Utilizing the front end of the bench, the transverse emittance and the energy distribution function of a He{sup +} beam extracted from a multi-line-cusp magnetic-field ion source 8 cm in diameter and 9 cm in length were measured. The results indicated that improvements in both formation of the plasma meniscus and reinforcement of pumping in the extraction region are necessary to produce a higher brightness He{sup +} beam.

  6. 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.

  7. Axisymmetric Solutions of the Euler Equations for Polytropic Gases

    NASA Astrophysics Data System (ADS)

    Zhang, Tong; Zheng, Yuxi

    We construct rigorously a three-parameter family of self-similar, globally bounded, and continuous weak solutions in two space dimensions for all positive time to the Euler equations with axisymmetry for polytropic gases with a quadratic pressure-density law. We use the axisymmetry and self-similarity assumptions to reduce the equations to a system of three ordinary differential equations, from which we obtain detailed structures of solutions besides their existence. These solutions exhibit familiar structures seen in hurricanes and tornadoes. They all have finite local energy and vorticity with well-defined initial and boundary values. These solutions include the one-parameter family of explicit solutions reported in a recent article of ours.

  8. 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.

  9. Polytropic Model Fits to the Globular Cluster NGC 2419 in Modified Newtonian Dynamics

    NASA Astrophysics Data System (ADS)

    Ibata, R.; Sollima, A.; Nipoti, C.; Bellazzini, M.; Chapman, S. C.; Dalessandro, E.

    2011-12-01

    We present an analysis of the globular cluster NGC 2419, using a polytropic model in modified Newtonian dynamics (MOND) to reproduce recently published high-quality data on the structure and kinematics of the system. We show that a specific MOND polytropic model of NGC 2419 suggested by a previous study can be completely ruled out by the data. Furthermore, the highest likelihood fit polytrope in MOND is a substantially worse model (by a factor of ~5000) than a Newtonian Michie model we studied previously. We conclude that the structure and dynamics of NGC 2419 favor Newtonian dynamics and do indeed challenge the MOND theory.

  10. Some non-linear interactions in polytropic gas cosmology: phase space analysis

    NASA Astrophysics Data System (ADS)

    Khurshudyan, Martiros

    2015-11-01

    There are various cosmological models with polytropic equation of state associated to dark energy. Polytropic EoS has important applications in astrophysics, therefore a study of it on cosmological framework continues to be interesting. From the other hand, there are various forms of interactions phenomenologically involved into the darkness of the universe able to solve important cosmological problems. This is a motivation for us to perform a phase space analysis of various cosmological scenarios where non-linear interacting polytropic gas models are involved. Dark matter is taken to be a pressureless fluid.

  11. Non-polytropic effect on shock-induced phase transitions in a hard-sphere system

    NASA Astrophysics Data System (ADS)

    Zheng, Yue; Zhao, Nanrong; Ruggeri, Tommaso; Sugiyama, Masaru; Taniguchi, Shigeru

    2010-07-01

    By adopting a simplified model of a non-polytropic hard-sphere system where heat capacity depends on the temperature, we demonstrate the importance of non-polytropic effect on the shock-induced phase transitions. We show explicitly that with the increase of the shock strength the perturbed temperature (the temperature after a shock) increases and the vibrational modes are gradually excited, and as a result, shock-induced phase transitions are qualitatively and quantitatively different from the phase transitions observed in a simple polytropic model. The effect on the admissibility (stability) of a shock wave is also analyzed.

  12. A Relationship Between Skin Thermal Conductivity and Gas Polytropic Index in an Open Atmospheric Balloon.

    NASA Astrophysics Data System (ADS)

    de La Torre, A.; Alexander, P.; Cornejo, J.

    2003-02-01

    With the assumption of a polytropic evolution for the lifting gas, the response of an ascending open atmospheric balloon to a monochromatic gravity wave is specified among other parameters by the heat balance with the surrounding air. If one considers the bubble of gas inside the open balloon as a thermodynamic system in contact through the balloon skin with a uniform thermal source (isothermic atmosphere), a relationship between the skin thermal conductivity and the polytropic index for the lifting gas [hydrogen (H2) or helium (He)] may be found. The results for both gases are extended to the case of a typical tropospheric linearly decreasing temperature profile. Constant and variable balloon skin thicknesses are studied for both background temperature profiles. The polytropic index is found to be lower for the changing skin and shows a sensitive difference between the two temperature profiles. The relationship between the thermal conductivity and polytropic index becomes abrupt only when the latter approaches the isothermal or adiabatic values.

  13. Ellipsoidal figures of equilibrium - Compressible models. [for self-gravitating Newtonian fluids in rotating polytropes

    NASA Technical Reports Server (NTRS)

    Lai, Dong; Rasio, Frederic A.; Shapiro, Stuart L.

    1993-01-01

    The results of Chandrasekhar (1969) are generalized to polytropes, using a formalism based on ellipsoidal energy variational principle to construct approximate stellar equilibrium solutions and study their stability. After reviewing the energy variational method and describing the approach, several equivalent stability conditions are established and secular vs. dynamical instabilities are discussed. Then, the equilibrium structure equations are derived for isolated, rotating polytropes, and axisymmetric configurations (compressible Maclaurin spheroids) are considered. Particular attention is given to triaxial configurations, either in a state of uniform rotation (generalizing the classical Jacobi ellipsoids) or with internal fluid motions of uniform vorticity (the compressible analogues of Riemann-S ellipsoids) and to the stability of these single star configurations. The compressible generalizations of the Roche and Roche-Riemann problems for a polytrope in orbit about a point-mass companion are solved, and the generalized Darwin problem for two identical polytropes in a binary is considered.

  14. 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.

  15. General polytropic magnetohydrodynamic cylinder under self-gravity

    NASA Astrophysics Data System (ADS)

    Lou, Yu-Qing; Xing, Heng-Rui

    2016-02-01

    Based on general polytropic (GP) magnetohydrodynamics (MHD), we offer a self-similar dynamic formalism for a magnetized, infinitely long, axially uniform cylinder of axisymmetry under self-gravity with radial and axial flows and with helical magnetic field. We identify two major classes of solution domains and obtain a few valuable MHD integrals in general. We focus on one class that has the freedom of prescribing a GP dynamic equation of state including the isothermal limit and derive analytic asymptotic solutions for illustration. In particular, we re-visit the isothermal MHD problem of Tilley & Pudritz (TP) and find that TP's main conclusion regarding the MHD solution behaviour for a strong ring magnetic field of constant toroidal flux-to-mass ratio Γϕ to be incorrect. As this is important for conceptual scenarios, MHD cylinder models, testing numerical codes and potential observational diagnostics of magnetized filaments in various astrophysical contexts, we show comprehensive theoretical analysis and reasons as well as extensive numerical results to clarify pertinent points in this Letter. In short, for any given Γϕ value be it small or large, the asymptotic radial scaling of the reduced mass density α(x) at sufficiently large x should always be ˜x-4 instead of ˜x-2 contrary to the major claim of TP.

  16. Polytropic scaling of a flow Z-pinch

    NASA Astrophysics Data System (ADS)

    Hughes, M. C.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Claveau, E. L.; Doty, S. A.; Forbes, E. G.; Kim, B.; Ross, M. P.; Weed, J. R.

    2015-11-01

    The ZaP Flow Z-Pinch project investigates the use of velocity shear to mitigate MHD instabilities. The ZaP-HD experiment produces 50 cm long pinches of varying radii. The power to the experiment is split between the plasma formation and acceleration process and the pinch assembly and compression process. Once the pinch is formed, low magnetic fluctuations indicate a quiescent, long-lived pinch. The split power supply allows more control of the pinch current than previous machine iterations, with a designed range from 50 to 150 kA. Radial force balance leads to the Bennett relation which indicates that as the pinch compresses due to increasing currents, the plasma pressure and/or linear density must change. Through ion spectroscopy and digital holographic interferometry coupled with magnetic measurements of the pinch current, the components of the Bennett relation can be fully measured. A scaling relation is then assumed to follow a polytrope as the pinch pressure, initially approximately 250 kPa, increases from an initially formed state to much higher values, approaching 100 MPa. A preliminary analysis of pinch scaling is shown corroborating with other diagnostics on the machine along with extrapolations to required currents for an HEDLP machine. This work is supported by grants from the U.S. Department of Energy and the U.S. National Nuclear Security Administration.

  17. General polytropic dynamic cylinder under self-gravity

    NASA Astrophysics Data System (ADS)

    Lou, Yu-Qing

    2015-12-01

    We explore self-similar hydrodynamics of general polytropic (GP) and isothermal cylinders of infinite length with axial uniformity and axisymmetry under self-gravity. Specific entropy conservation along streamlines serves as the dynamic equation of state. Together with possible axial flows, we construct classes of analytic and semi-analytic non-linear dynamic solutions for either cylindrical expansion or contraction radially by solving cylindrical Lane-Emden equations. By extensive numerical explorations and fitting trials in reference to asymptotes derived for large index n, we infer several convenient empirical formulae for characteristic solution properties of cylindrical Lane-Emden equations in terms of n values. A new type of asymptotic solutions for small x is also derived in the Appendix. These analyses offer hints for self-similar dynamic evolution of molecular filaments for forming protostars, brown dwarfs and gaseous planets and of large-scale gaseous arms or starburst rings in (barred) spiral galaxies for forming young massive stars. Such dynamic solutions are necessary starting background for further three-dimensional (in)stability analysis of various modes. They may be used to initialize numerical simulations and serve as important benchmarks for testing numerical codes. Such GP formalism can be further generalized to include magnetic field for a GP magnetohydrodynamic analysis.

  18. Ion Mobility-Mass Spectrometry Reveals Highly-Compact Intermediates in the Collision Induced Dissociation of Charge-Reduced Protein Complexes

    NASA Astrophysics Data System (ADS)

    Bornschein, Russell E.; Niu, Shuai; Eschweiler, Joseph; Ruotolo, Brandon T.

    2016-01-01

    Protocols that aim to construct complete models of multiprotein complexes based on ion mobility and mass spectrometry data are becoming an important element of integrative structural biology efforts. However, the usefulness of such data is predicated, in part, on an ability to measure individual subunits removed from the complex while maintaining a compact/folded state. Gas-phase dissociation of intact complexes using collision induced dissociation is a potentially promising pathway for acquiring such protein monomer size information, but most product ions produced are possessed of high charge states and elongated/string-like conformations that are not useful in protein complex modeling. It has previously been demonstrated that the collision induced dissociation of charge-reduced protein complexes can produce compact subunit product ions; however, their formation mechanism is not well understood. Here, we present new experimental evidence for the avidin (64 kDa) and aldolase (157 kDa) tetramers that demonstrates significant complex remodeling during the dissociation of charge-reduced assemblies. Detailed analysis and modeling indicates that highly compact intermediates are accessed during the dissociation process by both complexes. Here, we present putative pathways that describe the formation of such ions, as well as discuss the broader significance of such data for structural biology applications moving forward.

  19. Ion Mobility-Mass Spectrometry Reveals Highly-Compact Intermediates in the Collision Induced Dissociation of Charge-Reduced Protein Complexes.

    PubMed

    Bornschein, Russell E; Niu, Shuai; Eschweiler, Joseph; Ruotolo, Brandon T

    2016-01-01

    Protocols that aim to construct complete models of multiprotein complexes based on ion mobility and mass spectrometry data are becoming an important element of integrative structural biology efforts. However, the usefulness of such data is predicated, in part, on an ability to measure individual subunits removed from the complex while maintaining a compact/folded state. Gas-phase dissociation of intact complexes using collision induced dissociation is a potentially promising pathway for acquiring such protein monomer size information, but most product ions produced are possessed of high charge states and elongated/string-like conformations that are not useful in protein complex modeling. It has previously been demonstrated that the collision induced dissociation of charge-reduced protein complexes can produce compact subunit product ions; however, their formation mechanism is not well understood. Here, we present new experimental evidence for the avidin (64 kDa) and aldolase (157 kDa) tetramers that demonstrates significant complex remodeling during the dissociation of charge-reduced assemblies. Detailed analysis and modeling indicates that highly compact intermediates are accessed during the dissociation process by both complexes. Here, we present putative pathways that describe the formation of such ions, as well as discuss the broader significance of such data for structural biology applications moving forward. PMID:26323618

  20. 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.

  1. 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.

  2. General Polytropic Self-gravitating Cylinder Free-fall and Accreting Mass String with a Chain of Collapsed Objects

    NASA Astrophysics Data System (ADS)

    Lou, Yu-Qing; Hu, Xuyao

    2016-03-01

    We present a theoretical model framework for general polytropic (GP) hydrodynamic cylinder under self-gravity of infinite length with axial uniformity and axisymmetry. For self-similar dynamic solutions, we derive valuable integrals, analytic asymptotic solutions, sonic critical curves, shock conditions, and global numerical solutions with or without expansion shocks. Among others, we investigate various dynamic solutions featured with central free-fall asymptotic behaviours, corresponding to a collapsed mass string with a sustained dynamic accretion from a surrounding mass reservoir. Depending on the allowed ranges of a scaling index a < -1, such cylindrical dynamic mass accretion rate could be steady, increasing with time and decreasing with time. Physically, such a collapsed mass string or filament would break up into a sequence of sub-clumps and segments as induced by gravitational Jeans instabilities. Depending on the scales involved, such sub-clumps would evolve into collapsed objects or gravitationally bound systems. In diverse astrophysical and cosmological contexts, such a scenario can be adapted on various temporal, spatial and mass scales to form a chain of collapsed clumps and/or compact objects. Examples include the formation of chains of protostars, brown dwarfs and gaseous planets along molecular filaments; the formation of luminous massive stars along magnetized spiral arms and circumnuclear starburst rings in barred spiral galaxies; the formation of chains of compact stellar objects such as white dwarfs, neutron stars, and black holes along a highly condensed mass string. On cosmological scales, one can perceive the formation of chains of galaxies, chains of galaxy clusters or even chains of supermassive and hypermassive black holes in the Universe including the early Universe.

  3. General polytropic self-gravitating cylinder free-fall and accreting mass string with a chain of collapsed objects

    NASA Astrophysics Data System (ADS)

    Lou, Yu-Qing; Hu, Xu-Yao

    2016-06-01

    We present a theoretical model framework for general polytropic (GP) hydrodynamic cylinder under self-gravity of infinite length with axial uniformity and axisymmetry. For self-similar dynamic solutions, we derive valuable integrals, analytic asymptotic solutions, sonic critical curves, shock conditions, and global numerical solutions with or without expansion shocks. Among others, we investigate various dynamic solutions featured with central free-fall asymptotic behaviours, corresponding to a collapsed mass string with a sustained dynamic accretion from a surrounding mass reservoir. Depending on the allowed ranges of a scaling index a < -1, such cylindrical dynamic mass accretion rate could be steady, increasing with time and decreasing with time. Physically, such a collapsed mass string or filament would break up into a sequence of sub-clumps and segments as induced by gravitational Jeans instabilities. Depending on the scales involved, such sub-clumps would evolve into collapsed objects or gravitationally bound systems. In diverse astrophysical and cosmological contexts, such a scenario can be adapted on various temporal, spatial and mass scales to form a chain of collapsed clumps and/or compact objects. Examples include the formation of chains of proto-stars, brown dwarfs and gaseous planets along molecular filaments; the formation of luminous massive stars along magnetized spiral arms and circum-nuclear starburst rings in barred spiral galaxies; the formation of chains of compact stellar objects such as white dwarfs, neutron stars, and black holes along a highly condensed mass string. On cosmological scales, one can perceive the formation of chains of galaxies, chains of galaxy clusters or even chains of supermassive and hypermassive black holes in the Universe including the early Universe. All these chains referred to above include possible binaries.

  4. A compact electron beam ion source with integrated Wien filter providing mass and charge state separated beams of highly charged ions.

    PubMed

    Schmidt, M; Peng, H; Zschornack, G; Sykora, S

    2009-06-01

    A Wien filter was designed for and tested with a room temperature electron beam ion source (EBIS). Xenon charge state spectra up to the charge state Xe46+ were resolved as well as the isotopes of krypton using apertures of different sizes. The complete setup consisting of an EBIS and a Wien filter has a length of less than 1 m substituting a complete classical beamline setup. The Wien filter is equipped with removable permanent magnets. Hence total beam current measurements are possible via simple removal of the permanent magnets. In dependence on the needs of resolution a weak (0.2 T) or a strong (0.5 T) magnets setup can be used. In this paper the principle of operation and the design of the Wien filter meeting the requirements of an EBIS are briefly discussed. The first ion beam extraction and separation experiments with a Dresden EBIS are presented. PMID:19566197

  5. Compact accelerator

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    2007-02-06

    A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

  6. Ultrahigh charging of dust grains by the beam-plasma method for creating a compact neutron source

    NASA Astrophysics Data System (ADS)

    Akishev, Yu. S.; Karal'nik, V. B.; Petryakov, A. V.; Starostin, A. N.; Trushkin, N. I.; Filippov, A. V.

    2016-01-01

    Generation of high-voltage high-current electron beams in a low-pressure ( P = 0.1-1 Torr) gas discharge is studied experimentally as a function of the discharge voltage and the sort and pressure of the plasma-forming gas. The density of the plasma formed by a high-current electron beam is measured. Experiments on ultrahigh charging of targets exposed to a pulsed electron beam with an energy of up to 25 keV, an electron current density of higher than 1 A/cm2, a pulse duration of up to 1 μs, and a repetition rate of up to 1 kHz are described. A numerical model of ultrahigh charging of dust grains exposed to a high-energy electron beam is developed. The formation of high-energy positive ions in the field of negatively charged plane and spherical targets is calculated. The calculations performed for a pulse-periodic mode demonstrate the possibility of achieving neutron yields of higher than 106 s-1 cm-2 in the case of a plane target and about 109 s-1 in the case of 103 spherical targets, each with a radius of 250 μm.

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

    SciTech Connect

    Bini, D.; Cherubini, C.; Filippi, S.; Geralico, A.

    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.

  8. ROSSBY WAVE INSTABILITY IN LOCALLY ISOTHERMAL AND POLYTROPIC DISKS: THREE-DIMENSIONAL LINEAR CALCULATIONS

    SciTech Connect

    Lin, Min-Kai

    2012-07-20

    Numerical calculations of the linear Rossby wave instability (RWI) in global three-dimensional (3D) disks are presented. The linearized fluid equations are solved for vertically stratified, radially structured disks with either a locally isothermal or polytropic equation of state, by decomposing the vertical dependence of the perturbed hydrodynamic quantities into Hermite and Gegenbauer polynomials, respectively. It is confirmed that the RWI operates in 3D. For perturbations with vertical dependence assumed above, there is little difference in growth rates between 3D and two-dimensional (2D) calculations. Comparison between 2D and 3D solutions of this type suggests the RWI is predominantly a 2D instability and that 3D effects, such as vertical motion, can be interpreted as a perturbative consequence of the dominant 2D flow. The vertical flow around corotation, where vortex formation is expected, is examined. In locally isothermal disks, the expected vortex center remains in approximate vertical hydrostatic equilibrium. For polytropic disks, the vortex center has positive vertical velocity, whose magnitude increases with decreasing polytropic index n.

  9. 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.

  10. Viscous Accretion of a Polytropic Self-gravitating Disk in the Presence of Wind

    NASA Astrophysics Data System (ADS)

    Abbassi, Shahram; Nourbakhsh, Erfan; Shadmehri, Mohsen

    2013-03-01

    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 α and innovative β 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 β-disk, which indicates that in such disks gravitational instabilities can occur at various distances from the central accretor. So, the β-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 α-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 γ. It also may globally decrease if one prescribes a β-model for the viscosity. Moreover, in both viscosity models, the surface density and mass accretion rate diminish as the wind gets stronger or γ increases.

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

    SciTech Connect

    Abbassi, Shahram; Nourbakhsh, Erfan; Shadmehri, Mohsen E-mail: e.nourbakhsh@mail.sbu.ac.ir

    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.

  12. Gene transfer to human cells using retrovirus vectors produced by a new polytropic packaging cell line.

    PubMed Central

    Loiler, S A; DiFronzo, N L; Holland, C A

    1997-01-01

    We report here the construction of a new packaging cell line, called MPAC, that packages defective retroviral vectors in viral particles with envelope proteins derived from a Moloney mink cell focus-inducing (MCF) polytropic virus. We characterized the tropism of MPAC-packaged retroviral vectors and show that some human cell lines can be infected with these vectors while others cannot. In addition, we show that some human cells fully support MCF virus replication while others either partially or fully restrict MCF virus replication. PMID:9151879

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

    SciTech Connect

    Kuhn, S.; Kamran, M.; Jelic, N.; Kos, L.; Tskhakaya, D. jr; Tskhakaya, D. D. sr

    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.

  14. Analytic solutions for single and multiple cylinders of gravitating polytropes in magnetostatic equilibrium

    NASA Technical Reports Server (NTRS)

    Lerche, I.; Low, B. C.

    1980-01-01

    Exact analytic solutions for the static equilibrium of a gravitating plasma polytrope in the presence of magnetic fields are presented. The means of generating various equilibrium configurations to illustrate directly the complex physical relationships between pressure, magnetic fields, and gravity in self-gravitating systems is demonstrated. One of the solutions is used to model interstellar clouds suspended by magnetic fields against the galactic gravity such as may be formed by the Parker (1966) instability. It is concluded that the pinching effect of closed loops of magnetic fields in the clouds may be a dominant agent in further collapsing the clouds following their formation.

  15. Surface curvature singularities of polytropic spheres in Palatini f (R ,T ) gravity

    NASA Astrophysics Data System (ADS)

    Barrientos O., José; Rubilar, Guillermo F.

    2016-01-01

    We consider Palatini f (R ,T ) gravity models, similar to those introduced by Harko et al. (2012), where the gravitational Lagrangian is given by an arbitrary function of the curvature scalar R and of the trace of the energy-momentum tensor T . Interior spherical static solutions are studied considering the model of matter given by a perfect fluid configuration and a polytropic equation of state. We analyze the curvature singularities found previously for Palatini f (R ) gravity and discuss the possibility to remove them in some particular f (R ,T ) models. We show that it is possible to construct a restricted family of models for which these singularities are not present.

  16. 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.

  17. Innate immunity in the pathogenesis of polytropic retrovirus infection in the central nervous system

    PubMed Central

    Du, Min

    2016-01-01

    Neuroinflammation, including astrogliosis, microgliosis, and the production of proinflammatory cytokines and chemokines is a common response in the central nervous system (CNS) to virus infection, including retrovirus infection. However, the contribution of this innate immune response in disease pathogenesis remains unresolved. Analysis of the neuroinflammatory response to polytropic retrovirus infection in the mouse has provided insight into the potential contribution of the innate immune response to retrovirus-induced neurologic disease. In this model, retroviral pathogenesis correlates with the induction of neuroinflammatory responses including the activation of astrocytes and microglia, as well as the production of proinflammatory cytokines and chemokines. Studies of the neuroviru-lent determinants of the polytropic envelope protein as well as studies with knockout mice suggest that retroviral pathogenesis in the brain is multifaceted and that cytokine and chemokine production may be only one mechanism of disease pathogenesis. Analysis of the activation of the innate immune response to retrovirus infection in the CNS indicates that toll-like receptor 7 (TLR7) is a contributing factor to retrovirus-induced neuroinflammation, but that other factors can compensate for the lack of TLR7 in inducing both neuroinflammation and neurologic disease. PMID:18818884

  18. Compact baby Skyrmions

    SciTech Connect

    Adam, C.; Klimas, P.; Sanchez-Guillen, J.; Wereszczynski, A.

    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. 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.; Soni, G. D.

    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.

  20. Non-polytropic model with galactic winds for clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Fusco-Femiano, R.

    1994-12-01

    The intracluster gas of clusters of galaxies shows a metal enrichment with nearly solar abundances of metals. Two possible mechanisms are indicated for the injection of material by member galaxies: ram pressure stripping and protogalactic winds. In this article it is proposed a new static model that with respect to the non-polytropic model formulated by Cavaliere & Fusco-Femiano (1981), utilized to jointly fit all the available X-ray and optical imaging and spectroscopic data of the Coma cluster, includes also the contribution of supernovae-driven protogalactic winds to the heating and mass of the intracluster medium. The use of this model for the analysis of spatially resolved X-ray spectra should allow to discriminate between the wind and ram-pressure stripping scenario, regarding the injected energy and the metal enrichment of the intracluster gas.

  1. A further study on Palatini f(Script R)-theories for polytropic stars

    NASA Astrophysics Data System (ADS)

    Mana, Annalisa; Fatibene, Lorenzo; Ferraris, Marco

    2015-10-01

    After briefly reviewing the results about polytropic stars in Palatini f(Script R)-theories, we first show how these results rely on the assumption of a regular function f(Script R). In particular, singular models allow to extend the parameter interval in which no singularity is formed. Furthermore, we show how the conformal metric can be matched smoothly in the cases where the original metric generates a singularity. In fact, the singularity comes from a singular conformal factor which is continuous though not differentiable at the stellar surface. This suggests that the correct metric to be considered as physical is the conformal metric.This is relevant because, even when matching the original metric is possible, the use of the conformal metric generates different stellar models.

  2. The density structure and star formation rate of non-isothermal polytropic turbulence

    NASA Astrophysics Data System (ADS)

    Federrath, Christoph; Banerjee, Supratik

    2015-04-01

    The interstellar medium of galaxies is governed by supersonic turbulence, which likely controls the star formation rate (SFR) and the initial mass function (IMF). Interstellar turbulence is non-universal, with a wide range of Mach numbers, magnetic fields strengths and driving mechanisms. Although some of these parameters were explored, most previous works assumed that the gas is isothermal. However, we know that cold molecular clouds form out of the warm atomic medium, with the gas passing through chemical and thermodynamic phases that are not isothermal. Here we determine the role of temperature variations by modelling non-isothermal turbulence with a polytropic equation of state (EOS), where pressure and temperature are functions of gas density, P˜ ρ ^Γ, T ˜ ρΓ - 1. We use grid resolutions of 20483 cells and compare polytropic exponents Γ = 0.7 (soft EOS), Γ = 1 (isothermal EOS) and Γ = 5/3 (stiff EOS). We find a complex network of non-isothermal filaments with more small-scale fragmentation occurring for Γ < 1, while Γ > 1 smoothes out density contrasts. The density probability distribution function (PDF) is significantly affected by temperature variations, with a power-law tail developing at low densities for Γ > 1. In contrast, the PDF becomes closer to a lognormal distribution for Γ ≲ 1. We derive and test a new density variance-Mach number relation that takes Γ into account. This new relation is relevant for theoretical models of the SFR and IMF, because it determines the dense gas mass fraction of a cloud, from which stars form. We derive the SFR as a function of Γ and find that it decreases by a factor of ˜5 from Γ = 0.7 to 5/3.

  3. Relativistic self-similar dynamic collapses of black holes in general polytropic spherical clouds

    NASA Astrophysics Data System (ADS)

    Lian, Biao; Lou, Yu-Qing

    2014-02-01

    We study the hydrodynamic self-similar mass collapses of general polytropic (GP) spherical clouds to central Schwarzschild black holes and void evolution with or without shocks. In order to grossly capture characteristic effects of general relativity outside yet close to the event horizon of a Schwarzschild black hole and to avoid mathematical complexity, we adopt the approximation of the Paczynski-Wiita gravity to replace the simple Newtonian gravity in our model formulation. A new dimensionless parameter s appears with the physical meaning of the square of the ratio of the sound speed to the speed of light c. Various self-similar dynamic solutions are constructed for a polytropic index γ > 4/3. Two (for small enough s < 1) or no (for large enough s < 1) expansion-wave collapse solutions with central event horizons exist when γ > 4/3, representing the collapse of static singular GP spheres towards the central singularity of space-time. Such GP spherical dynamic mass collapse is shown to be highly efficient for the rapid formation of supermassive black holes (mass range of ˜106-1010 M⊙) in the early Universe or even hypermassive black holes (mass range of ˜1010-1012 M⊙) if extremely massive mass reservoirs could be sustained for a sufficiently long time, which may evolve into hard X-ray/gamma-ray sources or quasars according to their surroundings. Self-similar dynamic solutions of a GP gas are also proposed for the stellar mass black hole formation during the violent supernova explosion of a massive progenitor star, the time-scale of which is estimated of ˜10-3 s. Rebound shocks travelling in supernovae are also discussed based on our self-similar shock expansion solutions.

  4. Initial data for high-compactness black hole-neutron star binaries

    NASA Astrophysics Data System (ADS)

    Henriksson, Katherine; Foucart, François; Kidder, Lawrence E.; Teukolsky, Saul A.

    2016-05-01

    For highly compact neutron stars, constructing numerical initial data for black hole-neutron star binary evolutions is very difficult. We describe improvements to an earlier method that enable it to handle these more challenging cases. These improvements were found by invoking a general relaxation principle that may be helpful in improving robustness in other initial data solvers. We examine the case of a 6:1 mass ratio system in inspiral close to merger, where the star is governed by a polytropic {{Γ }}=2, an SLy, or an LS220 equation of state (EOS). In particular, we are able to obtain a solution with a realistic LS220 EOS for a star with compactness 0.26 and mass 1.98 M ⊙, which is representative of the highest reliably determined neutron star masses. For the SLy EOS, we can obtain solutions with a comparable compactness of 0.25, while for a family of polytropic equations of state, we obtain solutions with compactness up to 0.21, the largest compactness that is stable in this family. These compactness values are significantly higher than any previously published results.

  5. 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.

  6. Interacting Holographic Polytropic gas model of dark energy with hybrid expansion law in Bianchi type- VI 0 space-time

    NASA Astrophysics Data System (ADS)

    Azizur Rahman, M.; Ansari, M.

    2014-12-01

    In this paper, we have investigated a spatially homogeneous and anisotropic universe where dark energy interacts with dark matter. To obtain the exact solutions of Einstein's field equations, we consider a hybrid expansion law (HEL) which exhibits a transition of the universe from decelerating phase to the present accelerating phase. We observe that the model of the universe approaches isotropy under suitable condition and the coincidence parameter is found to be an increasing function of time. The physical and geometrical properties of the universe have been discussed which are found to be consistent with recent observations. Moreover, a correspondence between the holographic dark energy and polytropic gas model of dark energy is established. This correspondence allows us to reconstruct the potential and the dynamics for the scalar field of the polytropic gas which describes the accelerated expansion of the universe. We have also studied the statefinder parameters to characterize different phases of the evolution of the universe.

  7. Investigation of the Polytropic Relationship Between Density and Temperature Within Interplanetary Coronal Mass Ejections Using Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Riley, Pete; Gosling, J. T.; Pizzo, V. J.

    2001-01-01

    Single-point spacecraft measurements within coronal mass ejections (CMEs) often exhibit a negative correlation between electron density and temperature. At least two opposing interpretations have been suggested for this relationship. If, on one hand, these single spacecraft observations provide direct measures of the polytropic properties of the plasma, then they imply that the polytropic index for the electrons gamma(sub e) is often < 1. Moreover, since the electrons carry the bulk of the pressure (via their significantly higher temperature), this further implies that the dynamics of CME evolution are dominated by an effective polytropic index gamma(sub e)ff < 1. On the other hand, gamma < 1 implies that as the ejecta propagate away from the Sun and expand, they also heat up; a result clearly at odds with in situ observations. In contrast to these CME intervals, many studies have shown that the quiescent solar wind exhibits a positive correlation between electron density and temperature, suggesting that gamma(sub e) > 1. In this study we simulate the evolution of a variety of CME-like disturbances in the solar wind using a one-dimensional, single-fluid model, to address the interpretation of the relationship between electron density and temperature within CMEs at fixed locations in space. Although we strictly impose a polytropic relationship (with gamma = constant) throughout our simulations, we demonstrate that a variety of correlations can exist between density and temperature at fixed points. Furthermore, we demonstrate that the presence of only local uncorrelated random fluctuations in density and temperature can produce a negative correlation. Consequently, we conclude that these single-point observations of negative correlations between electron density and temperature cannot be used to infer the value of gamma(sub e). Instead, we suggest that entropy variations, together with the plasma's tendency to achieve pressure balance with its surroundings, are responsible for the observed profiles.

  8. Compact Reactor

    SciTech Connect

    Williams, Pharis E.

    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.

  9. Numerical Results for a Polytropic Cosmology Interpreted as a Dust Universe Producing Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Klapp, J.; Cervantes-Cota, J.; Chauvet, P.

    1990-11-01

    RESUMEN. A nivel cosmol6gico pensamos que se ha estado prodticiendo radiaci6n gravitacional en cantidades considerables dentro de las galaxias. Si los eventos prodnctores de radiaci6n gravitatoria han venido ocurriendo desde Ia epoca de Ia formaci6n de las galaxias, cuando menos, sus efectos cosmol6gicos pueden ser tomados en cuenta con simplicidad y elegancia al representar la producci6n de radiaci6n y, por consiguiente, su interacci6n con materia ordinaria fenomenol6gicamente a trave's de una ecuaci6n de estado politr6pica, como lo hemos mostrado en otros trabajos. Presentamos en este articulo resultados nunericos de este modelo. ABSTRACT A common believe in cosmology is that gravitational radiation in considerable quantities is being produced within the galaxies. Ifgravitational radiation production has been running since the galaxy formation epoch, at least, its cosmological effects can be assesed with simplicity and elegance by representing the production of radiation and, therefore, its interaction with ordinary matter phenomenologically through a polytropic equation of state as shown already elsewhere. We present in this paper the numerical results of such a model. K words: COSMOLOGY - GRAVITATION

  10. Receptor choice determinants in the envelope glycoproteins of amphotropic, xenotropic, and polytropic murine leukemia viruses.

    PubMed

    Battini, J L; Heard, J M; Danos, O

    1992-03-01

    The envelope glycoproteins (SU) of mammalian type C retroviruses possess an amino-terminal domain of about 200 residues, which is involved in binding a cell surface receptor. In this domain, highly conserved amino acid sequences are interrupted by two segments of variable length and sequence, VRA and VRB. We have studied the role of these variable regions in receptor recognition and binding by constructing chimeric molecules in which portions of the amino-terminal domains from amphotropic (4070A), xenotropic (NZB), and polytropic (MCF 247) murine leukemia virus SU proteins were permuted. These chimeras, which exchanged either one or two variable regions, were expressed at the surface of replication-defective viral particles by a pseudotyping assay. Wild-type or recombinant env genes were transfected into a cell line producing Moloney murine leukemia virus particles devoid of envelope glycoproteins in which a retrovirus vector genome carrying an Escherichia coli lacZ gene was packaged. The host range and sensitivity to interference of pseudotyped virions were assayed, and we observed which permutations resulted in receptor switch or loss of function. Our results indicate that the determinants of receptor choice are found within the just 120 amino acids of SU proteins. Downstream sequences contribute to the stabilization of the receptor-specific structure. PMID:1310758

  11. Rational design of hierarchical ZnO superstructures for efficient charge transfer: mechanistic and photovoltaic studies of hollow, mesoporous, cage-like nanostructures with compacted 1D building blocks.

    PubMed

    Chetia, Tridip Ranjan; Ansari, Mohammad Shaad; Qureshi, Mohammad

    2016-02-21

    Mesoporous and hollow zinc oxide (ZnO) hierarchical superstructures assembled with compact 1D building blocks that provide an efficient and faster transport pathway for photo-generated charge carriers have been synthesized using a biomass derived polysaccharide "alginic acid". To understand the interactions between the organic bio-template and inorganic growth units of ZnO in aqueous medium, the effects of additives such as the alginate ion (ALGI) and ammonium hydroxide (NH4OH), along with the controlled reaction conditions, are investigated using Field Emission Scanning Electron Microscopy (FESEM) and powder X-ray diffraction. Dynamic and steady-state photoluminescence measurements are carried out to understand the charge transfer processes in the compact 1D superstructures. Experimental analyses reveal that the alginate ions, under hydrothermal reaction conditions, act as a structure directing agent and assemble 1D ZnO nanorods (NRs) hierarchically while NH4OH assists the formation of ZnO growth units. A plausible mechanism for ZnO cage formation is proposed based on the experimental observations. Morphology dependent photovoltaic properties of ZnO heterostructures, i.e., for ZnO cages, ZnO NRs and ZnO PNPs, have been studied along with electrochemical impedance spectroscopy (EIS). Enhancement of ∼60% and ∼35% in power conversion efficiency (PCE) is observed in ZnO cage based devices as compared to ZnO NR- and ZnO PNP-based devices, respectively. PMID:26818181

  12. VIBRATION COMPACTION

    DOEpatents

    Hauth, J.J.

    1962-07-01

    A method of compacting a powder in a metal container is described including the steps of vibrating the container at above and below the resonant frequency and also sweeping the frequency of vibration across the resonant frequency several times thereby following the change in resonant frequency caused by compaction of the powder. (AEC)

  13. Compact monolithic capacitive discharge unit

    SciTech Connect

    Roesler, Alexander W.; Vernon, George E.; Hoke, Darren A.; De Marquis, Virginia K.; Harris, Steven M.

    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.

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

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae; Seo, Young Min; Hong, Seung Soo E-mail: wkim@astro.snu.ac.kr E-mail: sshong@astro.snu.ac.kr

    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.

  15. Cloning and characterization of a cell surface receptor for xenotropic and polytropic murine leukemia viruses.

    PubMed

    Tailor, C S; Nouri, A; Lee, C G; Kozak, C; Kabat, D

    1999-02-01

    Xenotropic and polytropic murine leukemia viruses (X-MLVs and P-MLVs) cross-interfere to various extents in non-mouse species and in wild Asian mice, suggesting that they might use a common receptor for infection. Consistent with this hypothesis, the susceptibility of some wild mice to X-MLVs has been mapped to the P-MLV receptor locus at the distal end of mouse chromosome 1. In this study, we report the isolation and characterization of a cDNA for the human X-MLV cell surface receptor (X-receptor) by using a human T lymphocyte cDNA library in a retroviral vector. The predicted X-receptor contains 696 amino acids with multiple hydrophobic potential membrane-spanning sequences and with weak homologies to the yeast proteins SYG1, of unknown function, and PHO81, which has been implicated in a system that regulates transport of inorganic phosphate. Expression of the X-receptor in Chinese hamster ovary cells, which are substantially resistant to P-MLVs and to X-MLVs, made them susceptible to both of these virus groups. The mouse homologue of the X-receptor was mapped by hybridization to the distal end of chromosome 1 at the same position as the P-MLV receptor gene Rmc1. These results strongly support the hypothesis that a common gene encodes the receptors for X-MLVs and P-MLVs, with the human X-receptor preferentially mediating X-MLV infections and the homologous protein of inbred mice mediating only P-MLV infections. We propose that X-MLVs and P-MLVs comprise a single family of retroviruses that have coevolved in response to diversification in X-receptor genes of the host. PMID:9927670

  16. Compact Storage

    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....

  17. Critical rotation of general-relativistic polytropic models simulating neutron stars: A post-Newtonian hybrid approximative scheme

    NASA Astrophysics Data System (ADS)

    Geroyannis, Vassilis S.; Karageorgopoulos, Vasileios G.

    2015-08-01

    We develop a “hybrid approximative scheme” in the framework of the post-Newtonian approximation for computing general-relativistic polytropic models simulating neutron stars in critical rigid rotation. We treat the differential equations governing such a model as a “complex initial value problem”, and we solve it by using the so-called “complex-plane strategy”. We incorporate into the computations the complete solution for the relativistic effects, this issue representing a significant improvement with regard to the classical post-Newtonian approximation, as verified by extended comparisons of the numerical results.

  18. Self-similar evolution of interplanetary magnetic clouds and Ulysses measurements of the polytropic index inside the cloud

    NASA Technical Reports Server (NTRS)

    Osherovich, Vladimir A.; Fainberg, J.; Stone, R. G.; MacDowall, R. J.; Berdichevsky, D.

    1997-01-01

    A self similar model for the expanding flux rope is developed for a magnetohydrodynamic model of interplanetary magnetic clouds. It is suggested that the dependence of the maximum magnetic field on the distance from the sun and the polytropic index gamma has the form B = r exp (-1/gamma), and that the ratio of the electron temperature to the proton temperature increases with distance from the sun. It is deduced that ion acoustic waves should be observed in the cloud. Both predictions were confirmed by Ulysses observations of a 1993 magnetic cloud. Measurements of gamma inside the cloud demonstrate sensitivity to the internal topology of the magnetic field in the cloud.

  19. Compaction managed mirror bend achromat

    DOEpatents

    Douglas, David

    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.

  20. Polymorphisms of the cell surface receptor control mouse susceptibilities to xenotropic and polytropic leukemia viruses.

    PubMed

    Marin, M; Tailor, C S; Nouri, A; Kozak, S L; Kabat, D

    1999-11-01

    The differential susceptibilities of mouse strains to xenotropic and polytropic murine leukemia viruses (X-MLVs and P-MLVs, respectively) are poorly understood but may involve multiple mechanisms. Recent evidence has demonstrated that these viruses use a common cell surface receptor (the X-receptor) for infection of human cells. We describe the properties of X-receptor cDNAs with distinct sequences cloned from five laboratory and wild strains of mice and from hamsters and minks. Expression of these cDNAs in resistant cells conferred susceptibilities to the same viruses that naturally infect the animals from which the cDNAs were derived. Thus, a laboratory mouse (NIH Swiss) X-receptor conferred susceptibility to P-MLVs but not to X-MLVs, whereas those from humans, minks, and several wild mice (Mus dunni, SC-1 cells, and Mus spretus) mediated infections by both X-MLVs and P-MLVs. In contrast, X-receptors from the resistant mouse strain Mus castaneus and from hamsters were inactive as viral receptors. These results suggest that X-receptor polymorphisms are a primary cause of resistances of mice to members of the X-MLV/P-MLV family of retroviruses and are responsible for the xenotropism of X-MLVs in laboratory mice. By site-directed mutagenesis, we substituted sequences between the X-receptors of M. dunni and NIH Swiss mice. The NIH Swiss protein contains two key differences (K500E in presumptive extracellular loop 3 [ECL 3] and a T582 deletion in ECL 4) that are both required to block X-MLV infections. Accordingly, a single inverse mutation in the NIH Swiss protein conferred X-MLV susceptibility. Furthermore, expression of an X-MLV envelope glycoprotein in Chinese hamster ovary cells interfered efficiently with X-MLV and P-MLV infections mediated by X-receptors that contained K500 and/or T582 but had no effect on P-MLV infections mediated by X-receptors that lacked these amino acids. In contrast, moderate expression of a P-MLV (MCF247) envelope glycoprotein did not cause substantial interference, suggesting that X-MLV and P-MLV glycoproteins interfere nonreciprocally with X-receptor-mediated infections. We conclude that P-MLVs have become adapted to utilize X-receptors that lack K500 and T582. A penalty for this adaptation is a reduced ability to interfere with superinfection. Because failure of interference is a hallmark of several exceptionally pathogenic retroviruses, we propose that it contributes to P-MLV-induced diseases. PMID:10516044

  1. Interacting Holographic Dark Energy, Future Singularity and Polytropic Gas Model of Dark Energy in Closed FRW Universe

    NASA Astrophysics Data System (ADS)

    Sarkar, Sanjay

    2016-01-01

    The present work deals with the accretion of two interacting fluids: dark matter and a hypothetical fluid as the holographic dark energy components onto wormhole in a non-flat FRW universe. First of all, following Cruz et al. (Phys. Lett. B 669, 271 2008), we obtained an exact solution of the Einstein's field equations. Solution describes effectively the actual acceleration and indicates a big rip type future singularity of the universe. After that we have studied the evolution of the mass of wormhole embedded in this FRW universe in order to reproduce a stable universe protected against future-time singularity. We found that the accretion of these dark components leads to a gradual increase of wormhole mass. It is also observed that contrary to the case as shown by Cruz et al. (Phys. Lett. B 669, 271 2008), the big rip singularity of the universe with a divergent Hubble parameter of this dark energy model may be avoided by a big trip. We have established a correspondence between the holographic dark energy with the polytropic gas dark energy model and obtained the potential as well as dynamics of the scalar field which describes the polytropic cosmology.

  2. Baryon currents in QCD with compact dimensions

    SciTech Connect

    Lucini, B.; Patella, A.; Pica, C.

    2007-06-15

    On a compact space with nontrivial cycles, for sufficiently small values of the radii of the compact dimensions, SU(N) gauge theories coupled with fermions in the fundamental representation spontaneously break charge conjugation, time reversal, and parity. We show at one loop in perturbation theory that a physical signature for this phenomenon is a nonzero baryonic current wrapping around the compact directions. The persistence of this current beyond the perturbative regime is checked by lattice simulations.

  3. Cracking of compact objects with electromagnetic field

    NASA Astrophysics Data System (ADS)

    Azam, M.; Mardan, S. A.; Rehman, M. A.

    2015-09-01

    In this paper, we investigate the role of electromagnetic field on the stability regions of charged self-gravitating compact objects by using the concept of cracking. For this purpose, we have applied local density perturbation scheme to the hydrostatic equilibrium equation as well as on physical parameters involved in the model. In particular, we have examined the cracking of charged compact objects like PSR J1614-2230, PSR J1903+327, Vela X-1, SMC X-1 and Cen X-3 with different values of charge. We conclude that these objects exhibit cracking and stability regions decreases with the increase of charge.

  4. 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.

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

    SciTech Connect

    Kong, Dali; Zhang, Keke; Schubert, Gerald; Anderson, John E-mail: K.Zhang@exeter.ac.uk

    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.

  6. 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.

  7. Dark soliton solution of the three-dimensional Gross-Pitaevskii equation with an isotropic harmonic potential and nonlinearity in polytropic approximation

    NASA Astrophysics Data System (ADS)

    Fan, Xinwei; Zhou, Yu; Li, Yalun; Wang, Ying; Zhou, Shuyu

    2016-02-01

    We study the three-dimensional Fermi gas in an isotropic harmonic trap during the Bardeen- Cooper-Schrieffer superfluid to Bose-Einstein condensate (BCS-BEC) crossover, which is modeled by using the generalized Gross-Pitaevskii equation (GGPE) in the polytropic approximation. We analytically solved the 3D GGPE with a coupled modulus-phase transformation without introducing any additional integrability constraint, reaching the dark soliton-like solution. We find that the dark soliton identified undergoes an oscillation with a constant period over the whole BCS-BEC crossover region, although the amplitude of the dark soliton varies with polytropic index, demonstrating the peculiar nonlinear properties for the system modeled by using the 3D GGPE.

  8. Near- and Far-field Response to Compact Acoustic Sources in Stratified Convection Zones

    NASA Astrophysics Data System (ADS)

    Cally, Paul S.

    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.

  9. A Three-dimensional Non-spherical Calculation Of The Rotationally Distorted Shape And Internal Structure Of A Model Of Jupiter With A Polytropic Index Of Unity

    NASA Astrophysics Data System (ADS)

    Zhang, Keke; Kong, D.; Schubert, G.; Anderson, J.

    2012-10-01

    An accurate calculation of the rotationally distorted shape and internal structure of Jupiter is required to understand the high-precision gravitational field that will be measured by the Juno spacecraft now on its way to Jupiter. We present a three-dimensional non-spherical numerical calculation of the shape and internal structure of a model of Jupiter 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 (1933) that is valid only for a slowly rotating gaseous planet, we apply it to a model of Jupiter whose rapid rotation causes a significant departure from spherical geometry. The two-dimensional distribution of the density and the pressure within Jupiter is then determined via a hybrid inverse approach by matching the a priori unknown coefficient in the equation of state to the observed shape of Jupiter. After obtaining the two-dimensional distribution of Jupiter's density, we then compute the zonal gravity coefficients and the total mass from the non-spherical Jupiter model that takes full account of rotation-induced shape changes. Our non-spherical model with a polytrope of unit index is able to produce the known mass and zonal gravitational coefficients of Jupiter. Chandrasekhar, S. 1933, The equilibrium of distorted polytropes, MNRAS 93, 390

  10. Compact Visible And Infrared Spectrometer

    NASA Technical Reports Server (NTRS)

    Torr, Marsha R.

    1992-01-01

    New compact spectrometers operate over broad wavelength ranges with moderate spectral resolution. Prototype measures spectral intensity simultaneously at all wavelengths from 3,700 to 11,700 Angstrom, with resolution of 12 Angstrom. Spectrum imaged onto strips on photocathode, then coupled via fiber-optic taper onto charge-coupled-device imager. Suitable for observation of weak phenomena as nocturnal airglow, and for observation of bright auroras and dayglow.

  11. Ceramic powder compaction

    SciTech Connect

    Glass, S.J.; Ewsuk, K.G.; Mahoney, F.M.

    1995-12-31

    With the objective of developing a predictive model for ceramic powder compaction we have investigated methods for characterizing density gradients in ceramic powder compacts, reviewed and compared existing compaction models, conducted compaction experiments on a spray dried alumina powder, and conducted mechanical tests and compaction experiments on model granular materials. Die filling and particle packing, and the behavior of individual granules play an important role in determining compaction behavior and should be incorporated into realistic compaction models. These results support the use of discrete element modeling techniques and statistical mechanics principals to develop a comprehensive model for compaction, something that should be achievable with computers with parallel processing capabilities.

  12. Accretion onto a charged higher-dimensional black hole

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Iftikhar, Sehrish

    2016-03-01

    This paper deals with the steady-state polytropic fluid accretion onto a higher-dimensional Reissner-Nordström black hole. We formulate the generalized mass flux conservation equation, energy flux conservation and relativistic Bernoulli equation to discuss the accretion process. The critical accretion is investigated by finding the critical radius, the critical sound velocity, and the critical flow velocity. We also explore gas compression and temperature profiles to analyze the asymptotic behavior. It is found that the results for the Schwarzschild black hole are recovered when q=0 in four dimensions. We conclude that the accretion process in higher dimensions becomes slower in the presence of charge.

  13. Viral RNAs Are Unusually Compact

    PubMed Central

    Gopal, Ajaykumar; Egecioglu, Defne E.; Yoffe, Aron M.; Ben-Shaul, Avinoam; Rao, Ayala L. N.; Knobler, Charles M.; Gelbart, William M.

    2014-01-01

    A majority of viruses are composed of long single-stranded genomic RNA molecules encapsulated by protein shells with diameters of just a few tens of nanometers. We examine the extent to which these viral RNAs have evolved to be physically compact molecules to facilitate encapsulation. Measurements of equal-length viral, non-viral, coding and non-coding RNAs show viral RNAs to have among the smallest sizes in solution, i.e., the highest gel-electrophoretic mobilities and the smallest hydrodynamic radii. Using graph-theoretical analyses we demonstrate that their sizes correlate with the compactness of branching patterns in predicted secondary structure ensembles. The density of branching is determined by the number and relative positions of 3-helix junctions, and is highly sensitive to the presence of rare higher-order junctions with 4 or more helices. Compact branching arises from a preponderance of base pairing between nucleotides close to each other in the primary sequence. The density of branching represents a degree of freedom optimized by viral RNA genomes in response to the evolutionary pressure to be packaged reliably. Several families of viruses are analyzed to delineate the effects of capsid geometry, size and charge stabilization on the selective pressure for RNA compactness. Compact branching has important implications for RNA folding and viral assembly. PMID:25188030

  14. Nonaxisymmetric Dynamic Instabilities of Rotating Polytropes. II. Torques, Bars, and Mode Saturation with Applications to Protostars and Fizzlers

    NASA Astrophysics Data System (ADS)

    Imamura, James N.; Durisen, Richard H.; Pickett, Brian K.

    2000-01-01

    Dynamic nonaxisymmetric instabilities in rapidly rotating stars and protostars have a range of potential applications in astrophysics, including implications for binary formation during protostellar cloud collapse and for the possibility of aborted collapse to neutron star densities at late stages of stellar evolution (``fizzlers''). We have recently presented detailed linear analyses for polytropes of the most dynamically unstable global modes, the barlike modes. These produce bar distortions in the regions near the rotation axis but have trailing spiral arms toward the equator. In this paper, we use our linear eigenfunctions to predict the early nonlinear behavior of the dynamic instability and compare these ``quasi-linear'' predictions with several fully nonlinear hydrodynamics simulations. The comparisons demonstrate that the nonlinear saturation of the barlike instability is due to the self-interaction gravitational torques between the growing central bar and the spiral arms, where angular momentum is transferred outward from bar to arms. We also find a previously unsuspected resonance condition that accurately predicts the mass of the bar regions in our own simulations and in those published by other researchers. The quasi-linear theory makes other accurate predictions about consequences of instability, including properties of possible end-state bars and increases in central density, which can be large under some conditions. We discuss in some detail the application of our results to binary formation during protostellar collapse and to the formation of massive rotating black holes.

  15. Michel accretion of a polytropic fluid with adiabatic index \\gamma \\gt 5/3: global flows versus homoclinic orbits

    NASA Astrophysics Data System (ADS)

    Chaverra, Eliana; Mach, Patryk; Sarbach, Olivier

    2016-05-01

    We analyze the properties of a polytropic fluid that is radially accreted into a Schwarzschild black hole. The case where the adiabatic index γ lies in the range of 1\\lt γ ≤slant 5/3 has been treated in previous work. In this article, we analyze the complementary range of 5/3\\lt γ ≤slant 2. To this purpose, the problem is cast into an appropriate Hamiltonian dynamical system, whose phase flow is analyzed. While, for 1\\lt γ ≤slant 5/3, the solutions are always characterized by the presence of a unique critical saddle point, we show that, when 5/3\\lt γ ≤slant 2, an additional critical point might appear, which is a center point. For the parametrization used in this paper, we prove that, whenever this additional critical point appears, there is a homoclinic orbit. Solutions corresponding to homoclinic orbits differ from standard transonic solutions with vanishing asymptotic velocities in two aspects: they are local (i.e., they cannot be continued to arbitrarily large radii); the dependence of the density or the value of the velocity on the radius is not monotonic.

  16. 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.

  17. 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

  18. Mechanics of tissue compaction.

    PubMed

    Turlier, Hervé; Maître, Jean-Léon

    2015-12-01

    During embryonic development, tissues deform by a succession and combination of morphogenetic processes. Tissue compaction is the morphogenetic process by which a tissue adopts a tighter structure. Recent studies characterized the respective roles of cells' adhesive and contractile properties in tissue compaction. In this review, we formalize the mechanical and molecular principles of tissue compaction and we analyze through the prism of this framework several morphogenetic events: the compaction of the early mouse embryo, the formation of the fly retina, the segmentation of somites and the separation of germ layers during gastrulation. PMID:26256955

  19. A nonclassical Radau collocation method for solving the Lane-Emden equations of the polytropic index 4.75 ≤ α < 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 α when 4.75 ≤ α ≤ 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.

  20. Reply to "Comment on the Paper ''On the Determination of Electron Polytrope Indices Within Coronal Mass Ejections in the Solar Wind'"'. Appendix 5

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.; Riley, P.; Skoug, R. M.

    2001-01-01

    We strongly disagree with the essence of the Osherovich (hereafter Osherovich) comment on one of our papers. The following paragraphs provide the basis of our disagreement and elaborate on why we believe that none of the concluding statements in his Comment are true. Our most important point is that one can apply the model developed by Osherovich and colleagues to real data obtained at a single point in space to determine the polytropic index within magnetic clouds if and only if the highly idealized assumptions of that model conform to physical reality. There is good reason to believe that those assumptions do not provide an accurate physical description of real magnetic clouds in the spherically expanding solar wind.

  1. SOIL COMPACTION MANAGEMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During temporary droughts that often limit agricultural production, soil compaction can hinder plant roots from reaching depths of soil where moisture is available. Many fields exhibit various degrees of soil compaction, resulting from variable soil types and past tillage and traffic practices. Va...

  2. 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...

  3. Multipolar universal relations between f -mode frequency and tidal deformability of compact stars

    NASA Astrophysics Data System (ADS)

    Chan, T. K.; Sham, Y.-H.; Leung, P. T.; Lin, L.-M.

    2014-12-01

    Though individual stellar parameters of compact stars usually demonstrate obvious dependence on the equation of state (EOS), EOS-insensitive universal formulas relating these parameters remarkably exist. In the present paper, we explore the interrelationship between two such formulas, namely the f -I relation connecting the f -mode quadrupole oscillation frequency ω2 and the moment of inertia I , and the I -Love-Q relations relating I , the quadrupole tidal deformability λ2, and the quadrupole moment Q , which have been proposed by Lau, Leung, and Lin [Astrophys. J. 714, 1234 (2010)] and Yagi and Yunes [Science 341, 365 (2013)], respectively. A relativistic universal relation between ωl and λl with the same angular momentum l =2 ,3 ,… , the so-called "diagonal f -Love relation" that holds for realistic compact stars and stiff polytropic stars, is unveiled here. An in-depth investigation in the Newtonian limit is further carried out to pinpoint its underlying physical mechanism and hence leads to a unified f -I -Love relation. We reach the conclusion that these EOS-insensitive formulas stem from a common physical origin—compact stars can be considered as quasiincompressible when they react to slow time variations introduced by f -mode oscillations, tidal forces and rotations.

  4. Dynamical compactness and sensitivity

    NASA Astrophysics Data System (ADS)

    Huang, Wen; Khilko, Danylo; Kolyada, Sergiĭ; Zhang, Guohua

    2016-05-01

    To link the Auslander point dynamics property with topological transitivity, in this paper we introduce dynamically compact systems as a new concept of a chaotic dynamical system (X , T) given by a compact metric space X and a continuous surjective self-map T : X → X. Observe that each weakly mixing system is transitive compact, and we show that any transitive compact M-system is weakly mixing. Then we discuss the relationships between it and other several stronger forms of sensitivity. We prove that any transitive compact system is Li-Yorke sensitive and furthermore multi-sensitive if it is not proximal, and that any multi-sensitive system has positive topological sequence entropy. Moreover, we show that multi-sensitivity is equivalent to both thick sensitivity and thickly syndetic sensitivity for M-systems. We also give a quantitative analysis for multi-sensitivity of a dynamical system.

  5. Compaction properties of isomalt.

    PubMed

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

    2009-08-01

    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 of agglomerated isomalt with a different ratio between 6-O-alpha-d-glucopyranosyl-d-sorbitol (GPS) and 1-O-alpha-d-glucopyranosyl-d-mannitol dihydrate (GPM). Powder flow properties, specific surface area and densities of the different types were investigated. Compactibility was investigated by compression of the tablets on a compaction simulator, simulating the compression on high-speed tabletting machines. Lubricant sensitivity was measured by compressing unlubricated tablets and tablets lubricated with 1% magnesium stearate on an instrumented hydraulic press. Sieved isomalt had excellent flow properties but the compactibility was found to be poor whereas the lubricant sensitivity was high. Milling resulted in both a strong increase in compactibility as an effect of the higher surface area for bonding and a decrease in lubricant sensitivity as an effect of the higher surface area to be coated with magnesium stearate. However, the flow properties of milled isomalt were too bad for use as filler-binder in direct compaction. Just as could be expected, agglomeration of milled isomalt by fluid bed agglomeration improved flowability. The good compaction properties and the low lubricant sensitivity were maintained. This effect is caused by an early fragmentation of the agglomerated material during the compaction process, producing clean, lubricant-free particles and a high surface for bonding. The different GPS/GPM ratios of the agglomerated isomalt types studied had no significant effect on the compaction properties. PMID:19327398

  6. 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.

  7. Compaction of poultry litter.

    PubMed

    Bernhart, M; Fasina, O O; Fulton, J; Wood, C W

    2010-01-01

    Poultry litter, a combination of accumulated chicken manure, feathers and bedding materials, is a potential feedstock for bioenergy and other value-added applications. The use of this waste product has been historically limited to within few miles of the place of generation because of its inherent low density. Compaction is one possible way to enhance the storage and transportation of the litter. This study therefore investigates the effect of moisture content (19.8-70.7%, d.b.) and pressure (0.8-8.4 MPa) on the compaction characteristics of poultry litter. Results obtained showed that the initial density of densified poultry litter, energy required for compaction and the strength of the densified material after 2 months of storage were significantly (P<0.05) affected by moisture content and pressure applied during compaction. The density of the compacted material was only affected by pressure applied during compaction after 2 months of storage. The specific energy required to produce the densified material varied from 0.25 to 2.00 kJ/kg and was significantly less than the energy required to produce pellets from biological materials. The results obtained from the study can be used for the economical design of on-farm compaction equipment for poultry litter. PMID:19733062

  8. Compact microchannel system

    DOEpatents

    Griffiths, Stewart

    2003-09-30

    The present invention provides compact geometries for the layout of microchannel columns through the use of turns and straight channel segments. These compact geometries permit the use of long separation or reaction columns on a small microchannel substrate or, equivalently, permit columns of a fixed length to occupy a smaller substrate area. The new geometries are based in part on mathematical analyses that provide the minimum turn radius for which column performance in not degraded. In particular, we find that straight channel segments of sufficient length reduce the required minimum turn radius, enabling compact channel layout when turns and straight segments are combined. The compact geometries are obtained by using turns and straight segments in overlapped or nested arrangements to form pleated or coiled columns.

  9. Compact turbidity meter

    NASA Technical Reports Server (NTRS)

    Hirschberg, J. G.

    1979-01-01

    Proposed monitor that detects back-reflected infrared radiation makes in situ turbidity measurements of lakes, streams, and other bodies of water. Monitor is compact, works well in daylight as at night, and is easily operated in rough seas.

  10. DNA compaction by azobenzene-containing surfactant

    SciTech Connect

    Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Santer, Svetlana

    2011-08-15

    We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

  11. Compact intracloud discharges

    NASA Astrophysics Data System (ADS)

    Smith, David Adam

    In November of 1993, mysterious signals recorded by a satellite-borne broadband VHF radio science experiment called Blackbeard led to a completely unexpected discovery. Prior to launch of the ALEXIS satellite, it was thought that its secondary payload, Blackbeard, would most often detect the radio emissions from lightning when its receiver was not overwhelmed by noise from narrowband communication carriers. Instead, the vast majority of events that triggered the instrument were isolated pairs of pulses that were one hundred times more energetic than normal thunderstorm electrical emissions. The events, which came to be known as TIPPs (for transionospheric pulse pairs), presented a true mystery to the geophysics community. At the time, it was not even known whether the events had natural or anthropogenic origins. After two and one half years of research into the unique signals, two ground-based receiver arrays in New Mexico first began to detect and record thunderstorm radio emissions that were consistent with the Blackbeard observations. On two occasions, the ground-based systems and Blackbeard even recorded emissions that were produced by the same exact events. From the ground-based observations, it has been determined that TIPP events are produced by brief, singular, isolated, intracloud electrical discharges that occur in intense regions of thunderstorms. These discharges have been dubbed CIDs, an acronym for compact intracloud discharges. During the summer of 1996, ground- based receiver arrays were used to record the electric field change signals and broadband HF emissions from hundreds of CIDs. Event timing that was accurate to within a few microseconds made possible the determination of source locations using methods of differential time of arrival. Ionospheric reflections of signals were recorded in addition to groundwave/line-of-sight signals and were used to determine accurate altitudes for the discharges. Twenty-four CIDs were recorded from three thunderstorms in the southwestern United States (US). The events occurred at altitudes between 8 and 11 km above mean sea level (MSL). Radar reflectivity data from two of the storms showed that CIDs occurred in close spatial proximity to thunderstorm cores with peak radar reflectivities of 47 to 58 dBZ. Over one hundred CIDs were also recorded from tropical cyclone Fausto off the coast of Mexico. These events occurred at altitudes between 15 and 17 km MSL. CIDs are singular discharges that usually occur in temporal isolation from other thunderstorm radio emissions on time scales of at least a few milliseconds. Calculations show that the discharges are vertically oriented and 300 to 1000 m in spatial extent. They produce average currents of several tens to a couple hundred kA for time periods of approximately 15 μs. Based on the results of a charge distribution model, the events occur in thunderstorm regions with charge densities on the order of several tens of nC/m3 and peak electric fields that are greater than 1 × 106 V/m. Both of these values are an order of magnitude greater than values previously measured or inferred from in situ thunderstorm measurements. The unique radio emissions from CIDs, in combination with their unprecedented physical characteristics, clearly distinguish the events from other types of previously observed thunderstorm electrical processes.

  12. Hypergroups of compact type

    NASA Astrophysics Data System (ADS)

    Filbir, Frank; Lasser, Rupert; Szwarc, Ryszard

    2005-06-01

    We consider commutative hypergroups with translation operators which are compact on L2 resp. L1. It will be shown that such hypergroups are necessarily discrete and that in the case of compact translations on L1 the support of the Plancherel measure coincides with the set of all characters and the hypergroup must be symmetric. Furthermore we will show that a certain type of Reiter's condition is fulfilled.

  13. 18 CFR 420.23 - Exempt uses under the Compact.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 2 2011-04-01 2011-04-01 false Exempt uses under the Compact. 420.23 Section 420.23 Conservation of 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)...

  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. Grain charging in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Ilgner, M.

    2012-02-01

    Context. Recent work identified a growth barrier for dust coagulation that originates in the electric repulsion between colliding particles. Depending on its charge state, dust material may have the potential to control key processes towards planet formation such as magnetohydrodynamic (MHD) turbulence and grain growth, which are coupled in a two-way process. Aims: We quantify the grain charging at different stages of disc evolution and differentiate between two very extreme cases: compact spherical grains and aggregates with fractal dimension Df = 2. Methods: Applying a simple chemical network that accounts for collisional charging of grains, we provide a semi-analytical solution. This allowed us to calculate the equilibrium population of grain charges and the ionisation fraction efficiently. The grain charging was evaluated for different dynamical environments ranging from static to non-stationary disc configurations. Results: The results show that the adsorption/desorption of neutral gas-phase heavy metals, such as magnesium, effects the charging state of grains. The greater the difference between the thermal velocities of the metal and the dominant molecular ion, the greater the change in the mean grain charge. Agglomerates have more negative excess charge on average than compact spherical particles of the same mass. The rise in the mean grain charge is proportional to N1/6 in the ion-dust limit. We find that grain charging in a non-stationary disc environment is expected to lead to similar results. Conclusions: The results indicate that the dust growth and settling in regions where the dust growth is limited by the so-called "electro-static barrier" do not prevent the dust material from remaining the dominant charge carrier.

  16. Limestone compaction: an enigma

    USGS Publications Warehouse

    Shinn, Eugene A.; Halley, Robert B.; Hudson, J. Harold; Lidz, Barbara H.

    1977-01-01

    Compression of an undisturbed carbonate sediment core under a pressure of 556 kg/cm2 produced a “rock” with sedimentary structures similar to typical ancient fine-grained limestones. Surprisingly, shells, foraminifera, and other fossils were not noticeably crushed, which indicates that absence of crushed fossils in ancient limestones can no longer be considered evidence that limestones do not compact.

  17. Soil Compaction Investigation.

    ERIC Educational Resources Information Center

    Turski, Mark P.

    1988-01-01

    Describes a lab investigation designed to introduce students to soil compaction and help them to learn to design and adapt procedures that scientists use when they plan and conduct controlled investigations. Provided are objectives, a list of materials, procedures, and a sample student handout. (CW)

  18. Compact optical transconductance varistor

    SciTech Connect

    Sampayan, Stephen

    2015-09-22

    A compact radiation-modulated transconductance varistor device having both a radiation source and a photoconductive wide bandgap semiconductor material (PWBSM) integrally formed on a substrate so that a single interface is formed between the radiation source and PWBSM for transmitting PWBSM activation radiation directly from the radiation source to the PWBSM.

  19. 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…

  20. The Boston Compact.

    ERIC Educational Resources Information Center

    Schwartz, Robert; Hargroves, Jeannette

    1987-01-01

    Discusses the Boston Compact, a 1982 agreement between Boston's business, governmental, and educational leaders to establish a system of priority hiring for high school graduates in return for the school system's assurance that it would improve education. Describes background and implementation since 1982, focusing on how well these goals have

  1. The Boston Compact.

    ERIC Educational Resources Information Center

    Caradonio, James; Spring, William

    1983-01-01

    The Boston Compact is a written agreement between the school system and the business community under which businesses agree to hire high school graduates in permanent jobs, provided that the schools prepare students through a program of career education, job readiness, and employability skills. (SK)

  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. Super-Compact Laser

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Microcosm, Inc. produced the portable Farfield-2 laser for field applications that require high power pulsed illumination. The compact design was conceived through research at Goddard Space Flight Center on laser instruments for space missions to carry out geoscience studies of Earth. An exclusive license to the key NASA patent for the compact laser design was assigned to Microcosm. The FarField-2 is ideal for field applications, has low power consumption, does not need water cooling or gas supplies, and produces nearly ideal beam quality. The properties of the laser also make it effective over long distances, which is one reason why NASA developed the technology for laser altimeters that can be toted aboard spacecraft. Applications for the FarField-2 include medicine, biology, and materials science and processing, as well as diamond marking, semiconductor line-cutting, chromosome surgery, and fluorescence microscopy.

  4. 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.

  5. 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.

  6. Compact Pinch Welder

    NASA Technical Reports Server (NTRS)

    Morgan, Gene E.; Thomas, Clark S.

    1991-01-01

    Spot welder designed for bonding insulated metal strips together. Compact, measuring only about 33.5 cm in its largest linear dimension. Pinch welder clamps electrodes on weldments with strong, repeatable force. Compressed air supplied through fitting on one handle. Small switch on same handle starts welding process when operator presses it with trigger. Provides higher, more repeatable clamping force than manually driven gun and thus produces weld joints of higher quality. Light in weight and therefore positioned precisely by operator.

  7. Compact power reactor

    DOEpatents

    Wetch, Joseph R.; Dieckamp, Herman M.; Wilson, Lewis A.

    1978-01-01

    There is disclosed a small compact nuclear reactor operating in the epithermal neutron energy range for supplying power at remote locations, as for a satellite. The core contains fuel moderator elements of Zr hydride with 7 w/o of 93% enriched uranium alloy. The core has a radial beryllium reflector and is cooled by liquid metal coolant such as NaK. The reactor is controlled and shut down by moving portions of the reflector.

  8. Compact infrared detector

    NASA Technical Reports Server (NTRS)

    Gupta, A.; Hong, S.; Moacanin, J.

    1981-01-01

    Broadband IR detector integrated into compact package for pollution monitoring and weather prediction is small, highly responsive, and immune to high noise. Sensing material is transparent sheet metalized with reflecting coating and overcoated with black material on same side. Pulse produced by chopping of infrared source beam creates transient "thermal lens" that temporarily defocuses laser beam probe. Detector monitoring beam measures defocusing which parallels infrared intensity.

  9. Fracture of explosively compacted aluminum particles in a cylinder

    NASA Astrophysics Data System (ADS)

    Frost, David; Loiseau, Jason; Goroshin, Sam; Zhang, Fan; Milne, Alec; Longbottom, Aaron

    2015-06-01

    The explosive compaction, fracture and dispersal of aluminum particles contained within a cylinder have been investigated experimentally and computationally. The aluminum particles were weakly confined in a cardboard tube and surrounded a central cylindrical burster charge. The compaction and fracture of the particles are visualized with flash radiography and the subsequent fragment dispersal with high-speed photography. The aluminum fragments produced are much larger than the original aluminum particles and similar in shape to those generated from the explosive fracture of a solid aluminum cylinder, suggesting that the shock transmitted into the aluminum compacts the powder to near solid density. The casing of the burster explosive (plastic-, copper-, and un-cased charges were used) had little influence on the fragment size. The effect of an air gap between the burster and the aluminum particles was also investigated. The particle motion inferred from the radiographs is compared with the predictions of a multimaterial hydrocode.

  10. 18 CFR 420.23 - Exempt uses under the Compact.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Exempt uses under the Compact. 420.23 Section 420.23 Conservation of Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-WATER SUPPLY CHARGES Water Supply Policy § 420.23 Exempt uses under...

  11. Physics of Compact Stellarators

    NASA Astrophysics Data System (ADS)

    Hirshman, S.

    1998-11-01

    Recent progress in the design and theoretical understanding of compact stellarators will be described. Interest in compact stellarators, for which the mean aspect ratio A < 4, is driven both by the desire to find attractive fusion reactors at an economical size and to merge the favorable features of tokamaks (good confinement, high beta) and stellarators (low recirculating power), thus achieving a hybrid device with finite bootstrap current, external kink stability (at moderate beta) in the absence of a conducting wall, and immunity to disruptions. The large transport ripple-driven losses of conventional stellarators are overcome in two basically different ways. Quasi-axisymmetric stellarators (QAS) achieve tokamak-like neoclassical transport levels by tailoring the magnetic field spectrum to be approximately axisymmetric in Boozer coordinates. These devices have bootstrap current profiles and magnitudes comparable to that in a tokamak. Unlike a tokamak, a QAS can have rotational transform profiles, modified by external coils, which have positive edge shear and hence good kink and neoclassical-tearing stability (island suppression). In contrast, quasi-omnigenous stellarators (QOS) rely on the confinement of J*-contours to achieve low transport levels. QOS can have transform profiles, and hence stability properties, similar to QAS, but with smaller values of self-consistent bootstrap currents. Powerful physics and coil optimization codes are being developed to design experiments to test these two compact stellarator approaches: a PoP-sized QAS to be built at PPPL and a concept-exploration experiment based on a QOS.

  12. CHARGE BOTTLE FOR A MASS SEPARATOR

    DOEpatents

    Davidson, P.H.

    1959-07-01

    Improved mass separator charge bottles are described for containing a dense charge of a chemical compound of copper, nickel, lead or other useful substance which is to be vaporized, and to the method of utilizing such improvcd charge bottles so that the chemical compound is vaporized from the under surface of the charge and thus permits the non-volatile portion thereof to fall to the bottom of the charge bottle where it does not form an obstacle to further evaporation. The charge bottle comprises a vertically disposed cylindrical portion, an inner re-entrant cylindrical portion extending axially and downwardly into the same from the upper end thereof, and evaporative source material in the form of a chemical compound compacted within the upper annular pontion of the charge bottle formed by the re-entrant cylindrical portion, whereby vapor from the chemical compound will pass outwardly from the charge bottle through an apertured closure.

  13. CHARGE IMBALANCE

    SciTech Connect

    Clarke, John

    1980-09-01

    The purpose of this article is to review the theory of charge imbalance, and to discuss its relevance to a number of experimental situations. We introduce the concepts of quasiparticle charge and charge imbalance, and discuss the generation and detection of charge imbalance by tunneling. We describe the relaxation of the injected charge imbalance by inelastic scattering processes, and show how the Boltzmann equation can be solved to obtain the steady state quasiparticle distribution and the charge relaxation rate. Details are given of experiments to measure charge imbalance and the charge relaxation rate when inelastic scattering is the predominant relaxation mechanism. Experiments on and theories of other charge relaxation mechanisms are discussed, namely relaxation via elastic scattering in the presence of energy gap anisotropy, or in the presence of a pair breaking mechanism such as magnetic impurities or an applied supercurrent or magnetic field. We describe three other situations in which charge imbalance occurs, namely the resistance of the NS interface, phase slip centers, and the flow of a supercurrent in the presence of a temperature gradient.

  14. Charge exchange and spectroscopy with isolated highly-charged ions

    NASA Astrophysics Data System (ADS)

    Guise, Nicholas D.; Brewer, Samuel M.; Tan, Joseph N.

    2012-06-01

    Compact ion traps can be useful in facilitating the study and manipulation of highly charged ions isolated in a controlled environment. Various ions of interest, including bare nuclei, are produced in the NIST electron beam ion trap (EBIT), extracted through a beamline that selects a single charge/mass species, then captured in a compact permanent magnet Penning trapootnotetextJ.N. Tan, S.M. Brewer, and N.D. Guise, at this meeting (poster). or RF trap. The isolated ions are detected optically or by ejection to a fast time-of-flight microchannel plate detector. In this room-temperature apparatus, demonstrated ion storage lifetimes exceed one second for species including Ne^10+ and Ar^13+, sufficiently long to measure certain metastable lifetimes via fluorescence detection,ootnotetextS.M. Brewer, N.D. Guise, and J.N. Tan, at this meeting. and to observe charge-exchange processes between trapped ions and residual background gas. A beam of Rydberg rubidium atoms, under development, may enable production of hydrogenlike ions in circular Rydberg states, via charge exchange with trapped bare nuclei; such one-electron ions are attractive for tests of theory and fundamental metrology.ootnotetextU.D. Jentschura, et al., Phys. Rev. Lett. 100, 160404 (2008). Other applications include spectroscopic studies of trapped highly charged ions relevant to atomic physics, astrophysics, and plasmas.

  15. 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.

  16. Intensity limitations in compact H{sup minus} cyclotrons

    SciTech Connect

    Baartman, R.A.

    1995-12-31

    At TRIUMF, we have demonstrated 2.5 mA in a compact H{sup -} cyclotron. It is worthwhile to explore possibility of going to even higher intensity. In small cyclotrons, vertical focusing vanishes at the center. The space charge tune shift further reduces vertical focusing, thus determining an upper limit on instantaneous current. Limit on average current is of course also dependent upon phase acceptance, but this can be made quite large in an H{sup -} cyclotron. Longitudinal space charge on the first turn can reduce the phase acceptance as well. For finite ion source brightness, another limit comes from bunching efficiency in presence of space charge forces. We present methods of calculating and optimizing these limits. In particular, we show that it is possible to achieve 10mA in a 50 MeV compact H{sup -} cyclotron.

  17. 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.

  18. Photometry of compact galaxies.

    NASA Technical Reports Server (NTRS)

    Shen, B. S. P.; Usher, P. D.; Barrett, J. W.

    1972-01-01

    Photometric histories of the N galaxies 3C 390.3 and PKS 0521-36. Four other compact galaxies, Markarian 9, I Zw 92, 2 Zw 136, and III Zw 77 showed no evidence of variability. The photometric histories were obtained from an exhaustive study of those plates of the Harvard collection taken with large aperture cameras. The images of all galaxies reported were indistinguishable from stars due to the camera f-ratios and low surface brightness of the outlying nebulosities of the galaxies. Standard techniques for the study of variable stars are therefore applicable.

  19. Compact gate valve

    DOEpatents

    Bobo, Gerald E.

    1977-01-01

    This invention relates to a double-disc gate valve which is compact, comparatively simple to construct, and capable of maintaining high closing pressures on the valve discs with low frictional forces. The valve casing includes axially aligned ports. Mounted in the casing is a sealed chamber which is pivotable transversely of the axis of the ports. The chamber contains the levers for moving the valve discs axially, and an actuator for the levers. When an external drive means pivots the chamber to a position where the discs are between the ports and axially aligned therewith, the actuator for the levers is energized to move the discs into sealing engagement with the ports.

  20. Forming Compact Massive Galaxies

    NASA Astrophysics Data System (ADS)

    van Dokkum, Pieter G.; Nelson, Erica June; Franx, Marijn; Oesch, Pascal; Momcheva, Ivelina; Brammer, Gabriel; Förster Schreiber, Natascha M.; Skelton, Rosalind E.; Whitaker, Katherine E.; van der Wel, Arjen; Bezanson, Rachel; Fumagalli, Mattia; Illingworth, Garth D.; Kriek, Mariska; Leja, Joel; Wuyts, Stijn

    2015-11-01

    In this paper we study a key phase in the formation of massive galaxies: the transition of star-forming galaxies into massive (Mstars ˜ 1011M⊙), compact (re ˜ 1 kpc) quiescent galaxies, which takes place from z ˜ 3 to z ˜ 1.5. We use HST grism redshifts and extensive photometry in all five 3D-HST/CANDELS fields, more than doubling the area used previously for such studies, and combine these data with Keck MOSFIRE and NIRSPEC spectroscopy. We first confirm that a population of massive, compact, star-forming galaxies exists at z ≳ 2, using K-band spectroscopy of 25 of these objects at 2.0 < z < 2.5. They have a median [N ii]/Hα ratio of 0.6, are highly obscured with SFR(tot)/SFR(Hα) ˜10, and have a large range of observed line widths. We infer from the kinematics and spatial distribution of Hα that the galaxies have rotating disks of ionized gas that are a factor of ˜2 more extended than the stellar distribution. By combining measurements of individual galaxies, we find that the kinematics are consistent with a nearly Keplerian fall-off from Vrot ˜ 500 km s-1 at 1 kpc to Vrot ˜ 250 km s-1 at 7 kpc, and that the total mass out to this radius is dominated by the dense stellar component. Next, we study the size and mass evolution of the progenitors of compact massive galaxies. Even though individual galaxies may have had complex histories with periods of compaction and mergers, we show that the population of progenitors likely followed a simple inside-out growth track in the size-mass plane of {{Δ }}{log}{r}{{e}}˜ 0.3{{Δ }}{log}{M}{{stars}}. This mode of growth gradually increases the stellar mass within a fixed physical radius, and galaxies quench when they reach a stellar density or velocity dispersion threshold. As shown in other studies, the mode of growth changes after quenching, as dry mergers take the galaxies on a relatively steep track in the size-mass plane.

  1. Compact electrostatic comb actuator

    DOEpatents

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  2. Compact Infrasonic Windscreen

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Shams, Qamar A.; Sealey, Bradley S.; Comeaux, Toby

    2005-01-01

    A compact windscreen has been conceived for a microphone of a type used outdoors to detect atmospheric infrasound from a variety of natural and manmade sources. Wind at the microphone site contaminates received infrasonic signals (defined here as sounds having frequencies <20 Hz), because a microphone cannot distinguish between infrasonic pressures (which propagate at the speed of sound) and convective pressure fluctuations generated by wind turbulence. Hence, success in measurement of outdoor infrasound depends on effective screening of the microphone from the wind. The present compact windscreen is based on a principle: that infrasound at sufficiently large wavelength can penetrate any barrier of practical thickness. Thus, a windscreen having solid, non-porous walls can block convected pressure fluctuations from the wind while transmitting infrasonic acoustic waves. The transmission coefficient depends strongly upon the ratio between the acoustic impedance of the windscreen and that of air. Several materials have been found to have impedance ratios that render them suitable for use in constructing walls that have practical thicknesses and are capable of high transmission of infrasound. These materials (with their impedance ratios in parentheses) are polyurethane foam (222), space shuttle tile material (332), balsa (323), cedar (3,151), and pine (4,713).

  3. Charging machine

    DOEpatents

    Medlin, John B.

    1976-05-25

    A charging machine for loading fuel slugs into the process tubes of a nuclear reactor includes a tubular housing connected to the process tube, a charging trough connected to the other end of the tubular housing, a device for loading the charging trough with a group of fuel slugs, means for equalizing the coolant pressure in the charging trough with the pressure in the process tubes, means for pushing the group of fuel slugs into the process tube and a latch and a seal engaging the last object in the group of fuel slugs to prevent the fuel slugs from being ejected from the process tube when the pusher is removed and to prevent pressure liquid from entering the charging machine.

  4. CONSIDERATION UNDER THE SURVEY ON ATTITUDES AMONG USERS TOWARD RECYCLING IN USED COMPACT APPLIANCES

    NASA Astrophysics Data System (ADS)

    Wada, Nariaki; Nakano, Kazuko

    In this paper, we consider establishment of recycling system under the result of questionary investigation about 10 items of used compact appliances. On gender basis, they have different comprehension about compact appliances recycling system, but make out the importance of it. By age bracket, young people have positive attitudes toward recycling, and great difference of burden charges for compact appliances disposal was seen; they are 1,522 yen in old generations, 1,531 yen in middle age generations, and 560 yen in young generations. This indicates that the recovery in their own backyard with the respect of age compositions at the area is needed for establishment of compact appliances recycling system.

  5. Wild mouse variants of envelope genes of xenotropic/polytropic mouse gammaretroviruses and their XPR1 receptors elucidate receptor determinants of virus entry.

    PubMed

    Yan, Yuhe; Knoper, Ryan C; Kozak, Christine A

    2007-10-01

    Mouse xenotropic and polytropic leukemia viruses (XMVs and PMVs) are closely related gammaretroviruses that use the XPR1 receptor for entry. To identify amino acid residues in XPR1 important for virus entry, we tested mouse cells derived from evolutionarily divergent species for susceptibility to prototypical PMVs, XMVs, and the wild mouse isolate CasE#1. CasE#1 has a variant XMV/PMV host range, and sequence analysis of the CasE#1 env gene identifies segments related to PMVs and XMVs. Cells from the Asian mouse species Mus pahari show a unique pattern of susceptibility to these three viruses; these cells are susceptible to XMVs and CasE#1 but are resistant to PMVs, whereas NIH 3T3 cells show the reciprocal pattern, susceptibility to only PMVs. The M. pahari XPR1 gene differs from that of NIH 3T3 in the two extracellular loops (ECLs) previously shown to mediate virus entry (M. Marin, C. S. Tailor, A. Nouri, S. L. Kozak, and D. Kabat, J. Virol. 73:9362-9368, 1999, and N. S. Van Hoeven and A. D. Miller, Retrovirology 2:76, 2005). Using transfected hamster cells expressing chimeric and mutated XPR1s, we demonstrated that the susceptibility differences between NIH 3T3 and M. pahari cells are receptor mediated, that PMV entry requires residues in ECL3, that the CasE#1 entry determinant is in ECL4, and that determinants for XMV entry are in both ECL3 and ECL4. Additional substitutions in ECL3 and ECL4 modulate virus susceptibility and suggest that ECL3 and ECL4 may contribute to the formation of a single virus receptor site. The position of M. pahari at the base of the Mus phylogenetic tree indicates that XPR1-mediated susceptibility to XMVs is the ancestral type in this genus and that the phenotypic variants of mouse XPR1 likely arose in conjunction with exposure to gammaretrovirus infections and coevolutionary adaptations in the viral envelope. PMID:17634227

  6. METHOD OF FORMING ELONGATED COMPACTS

    DOEpatents

    Larson, H.F.

    1959-05-01

    A powder compacting procedure and apparatus which produces elongated compacts of Be is described. The powdered metal is placed in a thin metal tube which is chemically compatible to lubricant, powder, atmosphere, and die material and will undergo a high degree of plastic deformation and have intermediate hardness. The tube is capped and placed in the die, and punches are applied to the ends. During the compacting stroke the powder seizes the tube and a thickening and shortening of the tube occurs. The tube is easily removed from the die, split, and peeled from the compact. (T.R.H.)

  7. Compact, Pneumatically Actuated Filter Shuttle

    NASA Technical Reports Server (NTRS)

    Leighy, Bradley D.

    2003-01-01

    A compact, pneumatically actuated filter shuttle has been invented to enable alternating imaging of a wind-tunnel model in two different spectral bands characteristic of the pressure and temperature responses of a pressure and temperature-sensitive paint. This filter shuttle could also be used in other settings in which there are requirements for alternating imaging in two spectral bands. Pneumatic actuation was chosen because of a need to exert control remotely (that is, from outside the wind tunnel) and because the power leads that would be needed for electrical actuation would pose an unacceptable hazard in the wind tunnel. The entire shuttle mechanism and its housing can be built relatively inexpensively [<$500 (prices as of year 2000)] from off-the-shelf parts. The shuttle mechanism (see Figure 1) is contained in a housing that has dimensions of 4 by 6 by 2 in. (about 10 by 15 by 5 cm). Two 2-in. (=5-cm)-diameter standard scientific-grade band-pass filters are mounted on sliding panels in a dual-track frame. The mechanism is positioned and oriented so the panels slide sideways with respect to the optical axis of a charge-coupled-device camera used for viewing the wind-tunnel model. The mechanism includes a pneumatic actuator connected to a linkage. The linkage converts the actuator stroke to a scissor-like motion that places one filter in front of the camera and the other filter out of the way. Optoelectronic sensors detect tabs on the sliding panels for verification of the proper positioning of the filters.

  8. Conformal invariance and string theory in compact space: Bosons

    NASA Astrophysics Data System (ADS)

    Jain, Sanjay; Shankar, R.; Wadia, Spenta R.

    1985-11-01

    The area law of the Nambu-Goto string is generalized to include a solid-angle-type term, which is purely topological in nature. Such a term exists and is unique provided the manifold M in which the string lives satisfies certain topological conditions. This generalization may be useful to maintain conformal invariance in case M is compact. Using methods of Polyakov and Friedan we identify the conformal anomaly coefficient with the central charge of the Virasoro algebra of this string theory. As an illustration we choose M to be a compact Lie group and compute the anomaly coefficient following the work of Knizhnik and Zamolodchikov.

  9. Design of a compact structure cancer therapy synchrotron

    NASA Astrophysics Data System (ADS)

    Yang, J. C.; Shi, J.; Chai, W. P.; Xia, J. W.; Yuan, Y. J.; Li, Y.

    2014-08-01

    HIMM, a new compact accelerator facility dedicated to carbon cancer therapy, has been designed and is presently under construction. The synchrotron has a compact structure that exhibits a circumference of only 56.2 m. The charge exchange injection (CEI) method is adopted for synchrotron injection with a carbon-ion energy of 7 MeV/u. The third-order resonance and RF-Knock Out scheme are adopted in this machine. The general design of the machine and injection/extraction simulation results is discussed in this paper.

  10. Charge-pump voltage converter

    DOEpatents

    Brainard, John P.; Christenson, Todd R.

    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. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A.

    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.

  12. Compact artificial hand

    NASA Technical Reports Server (NTRS)

    Wiker, G. A.; Mann, W. A. (Inventor)

    1979-01-01

    A relatively simple, compact artificial hand, is described which includes hooks pivotally mounted on first frame to move together and apart. The first frame is rotatably mounted on a second frame to enable "turning at the wrist" movement without limitation. The second frame is pivotally mounted on a third frame to permit 'flexing at the wrist' movement. A hook-driving motor is fixed to the second frame but has a shaft that drives a speed reducer on the first frame which, in turn, drives the hooks. A second motor mounted on the second frame, turns a gear on the first frame to rotate the first frame and the hooks thereon. A third motor mounted on the third frame, turns a gear on a second frame to pivot it.

  13. Compact ultraviolet laser

    NASA Astrophysics Data System (ADS)

    Baird, Brian Walter

    1997-09-01

    This dissertation presents theoretical analysis and experimental investigation of a compact ultraviolet laser, comprising an unstable resonator semiconductor (URSL) laser-pumped potassium titanyl phosphate (KTP) periodically segmented waveguide (PSW) laser. A comprehensive survey of existing short wavelength visible and near ultraviolet laser technologies suitable for the development of compact ultraviolet lasers is presented. This survey establishes the suitability of a diode-pumped KTP PSW laser as an attractive approach for developing a compact ultraviolet laser. Requirements for an efficient diode-pumped KTP PSW laser are given, leading to the selection of a frequency-stabilized URSL and hydrothermal KTP PSWs as the component technologies to be developed and integrated. Since the design requirements for the URSL and KTP PSW are critically dependent on a thorough understanding of the spatial mode properties of KTP PSWs, analyses and modeling of the spatial mode properties of these devices is presented using effective index method (EIM) and beam propagation method (BPM) models. In addition, a new expression for the normalized conversion efficiency is presented which explicitly incorporates the dependence of this important parameter on the lateral variation of the refractive index and d coefficient. To assess the theoretical performance of an URSL-pumped KTP PSW, the BPM model was extended to incorporate second harmonic generation. This represents an important contribution to the development of numerical methods for modeling nonlinear waveguides, in general, and provides important information on the cooperative effects of diffraction and spatial mode beating on the SHG output from KTP PSWs. Extensive optical characterization of NUV SHG in hydrothermal KTP PSWs using an argon-ion laser-pumped Ti:Sapphire laser as the infrared laser pump source is presented. Spectral characterization, spatial mode characterization, and the temperature dependence of the QPM wavelength are presented. This work includes results for the highest cw output powers reported for NUV SHG output from a laser-pumped KTP PSW. In an important step towards demonstration of an URSL- pumped KTP PSW laser, fabrication methods and test results ate reported for half-symmetric, low magnification SQW AlGaAs URSLs emitting at 770 nm and designed for use as diode pump sources for hydrothermal KTP PSWs. These devices utilize a 200 /mu m × 500 /mu m active region profile and were focused-ion- beam micromachined to achieve a total resonator magnification of 2.9. The first demonstration of high brightness, single-longitudinal mode operation from a core grating URSL is reported. This dissertation concludes with results for the first demonstration of an URSL-pumped KTP waveguide laser. This compact ultraviolet laser represents a pioneering effort to take advantage of the high cw output powers available from high brightness URSLs to increase the SH output powers obtainable from diode-pumped nonlinear waveguide lasers and to extend the useful spectral range from these sources into the near ultraviolet.

  14. 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.

  15. Compact acoustic refrigerator

    DOEpatents

    Bennett, G.A.

    1992-11-24

    A compact acoustic refrigeration system 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. 18 figs.

  16. Atacama compact array antennas

    NASA Astrophysics Data System (ADS)

    Saito, M.; Inatani, J.; Nakanishi, K.; Saito, H.; Iguchi, S.

    2012-09-01

    The ACA (Atacama Compact Array) system is an important element of ALMA and consists of four ACA 12-m antennas and twelve ACA 7-m antennas. The ACA system aims to acquire the total power data with four 12-m antennas and the short baseline interferometer data with 7-m antennas. The ACA system also increases reliability of the interferometer maps of astronomical sources larger than the field view of the 12-m antenna. The science performance of these antennas has been extensively verified at OSF (operation support facility) at an elevation of 2900 m in Atacama desert in northern Chile since 2007. The pointing performance has been verified with a dedicated optical pointing telescope, the servo performance is tested with angle encoders, and the surface accuracy has been measured with a radio holography method. Both ACA 12-m antennas and 7-m antennas have been successfully demonstrated to meet the very stringent ALMA specifications.

  17. Multipurpose Compact Spectrometric Unit

    SciTech Connect

    Bocarov, Viktor; Cermak, Pavel; Mamedov, Fadahat; Stekl, Ivan

    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.

  18. 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.

  19. Compact vacuum insulation embodiments

    DOEpatents

    Benson, David K.; Potter, Thomas F.

    1992-01-01

    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.

  20. 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.

  1. Compact vacuum insulation

    DOEpatents

    Benson, David K.; Potter, Thomas F.

    1993-01-01

    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.

  2. 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.

  3. The Finslerian compact star model

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Paul, Nupur; De, S. S.; Ray, Saibal; Jafry, Md. Abdul Kayum

    2015-11-01

    We construct a toy model for compact stars based on the Finslerian structure of spacetime. By assuming a particular mass function, we find an exact solution of the Finsler-Einstein field equations with an anisotropic matter distribution. The solutions are revealed to be physically interesting and pertinent for the explanation of compact stars.

  4. Relativistic Charged Star Solutions in Higher Dimensions

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, P. K.; Deb, R.; Paul, B. C.

    2014-05-01

    We present a class of relativistic solutions of the Einstein-Maxwell equations for a spherically symmetric charged static fluid sphere in higher dimensions. The interior space at t= constant considered here possess ( D-1) dimensional spheroidal geometry described by a higher dimensional Vaidya-Tikekar metric. A class of new static solutions of coupled Einstein-Maxwell equations is obtained in a D-dimensional space-time by prescribing the geometry of a ( D-1) dimensional hyper spheroid in hydrostatic equilibrium. The solutions of the Einstein-Maxwell field equations are employed to obtain relativistic models for charged compact stars with a suitable law for variation of electric field in terms of the charged fluid content in the interior of the sphere. The central density is found to depend on the space-time dimensions and a physically realistic model is permitted for ( D≥4). The validity of both Strong Energy Condition (SEC), Weak Energy Condition (WEC) are studied for a given configuration and compactness of compact objects. We found new class of solutions with interesting stellar models where it permits a star with a core having different property than the rest which however disappears in higher dimensions. The effect of dimensions on the Electric charge of the compact object is studied. We note that the upper limit of the electric field is determined by the space-time dimensions which are determined.

  5. A Compact Ring Design with Tunable Momentum Compaction

    SciTech Connect

    Sun, Y.; ,

    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.

  6. Engineering Prototype for a Compact Medical Dielectric Wall Accelerator

    NASA Astrophysics Data System (ADS)

    Zografos, Anthony; Hening, Andy; Joshkin, Vladimir; Leung, Kevin; Pearson, Dave; Pearce-Percy, Henry; Rougieri, Mario; Parker, Yoko; Weir, John; Blackfield, Donald; Chen, Yu-Jiuan; Falabella, Steven; Guethlein, Gary; Poole, Brian; Hamm, Robert W.; Becker, Reinard

    2011-12-01

    A compact accelerator system architecture based on the dielectric wall accelerator (DWA) for medical proton beam therapy has been developed by the Compact Particle Acceleration Corporation (CPAC). The major subsystems are a Radio Frequency Quadrupole (RFQ) injector linac, a pulsed kicker to select the desired proton bunches, and a DWA linear accelerator incorporating a high gradient insulator (HGI) with stacked Blumleins to produce the required acceleration energy. The Blumleins are switched with solid state laser-driven optical switches integrated into the Blumlein assemblies. Other subsystems include a high power pulsed laser, fiber optic distribution system, electrical charging system, and beam diagnostics. An engineering prototype has been constructed and characterized, and these results will be used within the next three years to develop an extremely compact 150 MeV system capable of modulating energy, beam current, and spot size on a shot-to-shot basis. This paper presents the details the engineering prototype, experimental results, and commercialization plans.

  7. Engineering Prototype for a Compact Medical Dielectric Wall Accelerator

    SciTech Connect

    Zografos, Anthony; Hening, Andy; Joshkin, Vladimir; Leung, Kevin; Pearson, Dave; Pearce-Percy, Henry; Rougieri, Mario; Parker, Yoko; Weir, John; Blackfield, Donald; Chen, Yu-Jiuan; Falabella, Steven; Guethlein, Gary; Poole, Brian; Hamm, Robert W.; Becker, Reinard

    2011-12-13

    A compact accelerator system architecture based on the dielectric wall accelerator (DWA) for medical proton beam therapy has been developed by the Compact Particle Acceleration Corporation (CPAC). The major subsystems are a Radio Frequency Quadrupole (RFQ) injector linac, a pulsed kicker to select the desired proton bunches, and a DWA linear accelerator incorporating a high gradient insulator (HGI) with stacked Blumleins to produce the required acceleration energy. The Blumleins are switched with solid state laser-driven optical switches integrated into the Blumlein assemblies. Other subsystems include a high power pulsed laser, fiber optic distribution system, electrical charging system, and beam diagnostics. An engineering prototype has been constructed and characterized, and these results will be used within the next three years to develop an extremely compact 150 MeV system capable of modulating energy, beam current, and spot size on a shot-to-shot basis. This paper presents the details the engineering prototype, experimental results, and commercialization plans.

  8. Gravitational waves from rotating neutron stars and compact binary systems

    NASA Astrophysics Data System (ADS)

    Wade, Leslie E., IV

    It is widely anticipated that the first direct detections of gravitational waves will be made by advanced gravitational-wave detectors, such as the two Laser Interferometer Gravitational-wave Observatories (LIGO) and the Virgo interferometer. In preparation for the advanced detector era, I have worked on both detection and post-detection efforts involving two gravitational wave sources: isolated rotating neutron stars (NSs) and compact binary coalescences (CBCs). My dissertation includes three main research projects: 1) a population synthesis study assessing the detectability of isolated NSs, 2) a CBC search for intermediate-mass black-hole binaries (IMBHBs), and 3) new methods for directly measuring the neutron-star (NS) equation of state (EOS). Direct detections of gravitational waves will enrich our current astrophysical knowledge. One such contribution will be through population synthesis of isolated NSs. My collaborators and I show that advanced gravitational-wave detectors can be used to constrain the properties of the Galactic NS population. Gravitational wave detections can also shine light on a currently mysterious astrophysical object: intermediate mass black holes. In developing the IMBHB search, we performed a mock data challenge where signals with total masses up to a few hundred solar masses were injected into recolored data from LIGO's sixth science run. Since this is the first time a matched filter search has been developed to search for IMBHBs, I discuss what was learned during the mock data challenge and how we plan to improve the search going forward. The final aspect of my dissertation focuses on important post-detection science. I present results for a new method of directly measuring the NS EOS. This is done by estimating the parameters of a 4-piece polytropic EOS model that matches theoretical EOS candidates to a few percent. We show that advanced detectors will be capable of measuring the NS radius to within a kilometer for stars with canonical masses. However, this can only be accomplished with binary NS waveform models that are accurate to the rich EOS physics that happens near merger. We show that the waveforms typically used to model binary NS systems result in unavoidable systematic error that can significantly bias the estimation of the NS EOS.

  9. A compact acoustic recorder

    NASA Astrophysics Data System (ADS)

    Stein, Ronald

    1989-09-01

    The design and operation of a portable compact acoustic recorder is discussed. Designed to be used in arctic conditions for applications that require portable equipment, the device is configured to fit into a lightweight briefcase. It will operate for eight hours at -40 F with heat provided by a hot water bottle. It has proven to be an effective scientific tool in the measurement of underwater acoustic signals in arctic experiments. It has also been used successfully in warmer climates, e.g., in recording acoustic signals from small boats with no ac power. The acoustic recorder's cost is moderate since it is based on a Sony Walkman Professional (WM-D6C) tape recorder playback unit. A speaker and battery assembly and a hydrophone interface electronic assembly complete the system electronics. The interface assembly supplies a number of functions, including a calibration tone generator, an audio amplifier, and a hydrophone interface. Calibrated acoustic recordings can be made by comparing the calibration tone amplitude with the acoustic signal amplitude. The distortion of the recording is minimized by using a high quality, consumer tape recorder.

  10. Compact THz imaging detector

    NASA Astrophysics Data System (ADS)

    Newman, J. Daniel; Lee, Paul P. K.; Sacco, Andrew P.; Chamberlain, Thomas B.; Willems, Dave A.; Fiete, Robert D.; Bocko, Mark V.; Ignotovic, Zeljko; Pipher, Judith L.; McMurtry, Craig W.; Zhang, Xi-Cheng; Rhodes, David B.; Ninkov, Zoran

    2013-05-01

    We describe preliminary design, modeling and test results for the development of a monolithic, high pixel density, THz band focal plane array (FPA) fabricated in a commercial CMOS process. Each pixel unit cell contains multiple individual THz band antennae that are coupled to independent amplifiers. The amplified signals are summed either coherently or incoherently to improve detection (SNR). The sensor is designed to operate at room temperature using passive or active illumination. In addition to the THz detector, a secondary array of Visible or SWIR context imaging pixels are interposed in the same area matrix. Multiple VIS/SWIR context pixels can be fabricated within the THz pixel unit cell. This provides simultaneous, registered context imagery and "Pan sharpening" MTF enhancement for the THz image. The compact THz imaging system maximizes the utility of a ~ 300 μm x 300 μm pixel area associated with the optical resolution spot size for a THz imaging system operating at a nominal ~ 1.0 THz spectral frequency. RF modeling is used to parameterize the antenna array design for optimal response at the THz frequencies of interest. The quarter-wave strip balanced bow-tie antennae are optimized based on the semiconductor fabrication technology thin-film characteristics and the CMOS detector input impedance. RF SPICE models enhanced for THz frequencies are used to evaluate the predicted CMOS detector performance and optimal unit cell design architecture. The models are validated through testing of existing CMOS ROICs with calibrated THz sources.

  11. 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.

  12. Compact vacuum insulation

    DOEpatents

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

    1992-10-27

    Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.

  13. Compact vacuum insulation

    DOEpatents

    Benson, David K.; Potter, Thomas F.

    1992-01-01

    Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases therebetween are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and variious laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels.

  14. Compact Dexterous Robotic Hand

    NASA Technical Reports Server (NTRS)

    Lovchik, Christopher Scott (Inventor); Diftler, Myron A. (Inventor)

    2001-01-01

    A compact robotic hand includes a palm housing, a wrist section, and a forearm section. The palm housing supports a plurality of fingers and one or more movable palm members that cooperate with the fingers to grasp and/or release an object. Each flexible finger comprises a plurality of hingedly connected segments, including a proximal segment pivotally connected to the palm housing. The proximal finger segment includes at least one groove defining first and second cam surfaces for engagement with a cable. A plurality of lead screw assemblies each carried by the palm housing are supplied with power from a flexible shaft rotated by an actuator and output linear motion to a cable move a finger. The cable is secured within a respective groove and enables each finger to move between an opened and closed position. A decoupling assembly pivotally connected to a proximal finger segment enables a cable connected thereto to control movement of an intermediate and distal finger segment independent of movement of the proximal finger segment. The dexterous robotic hand closely resembles the function of a human hand yet is light weight and capable of grasping both heavy and light objects with a high degree of precision.

  15. Solar charging

    SciTech Connect

    Heckeroth, S.; McLees, C.

    1996-11-01

    Concern about the depletion of non-renewable energy resources and the life threatening pollution and climatic changes caused by their use has led to a renewed interest in passive solar design. However, transportation consumes four times the energy used in housing and causes about 10 times the air pollution because of its total reliance on petroleum. This paper will suggest direct solar charging opportunities that can be integrated into the built environment. Major advances in electric vehicle (EV) and photovoltaic (PV) technologies will soon make solar charging a viable option for transportation. More efficient motors, high-power controllers, quick chargers and new developments in battery technology will soon make electric vehicles have performance comparable to gas vehicles. The rise in efficiency, the decreasing cost and the integration of photovoltaic panels as roofing will make workplace and home solar charging an economic alternative to the gas pump.

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

    SciTech Connect

    Fort, H.; Gambini, R.

    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.}

  17. Simulation of roller compaction using a laboratory scale compaction simulator.

    PubMed

    Zinchuk, Andrey V; Mullarney, Matthew P; Hancock, Bruno C

    2004-01-28

    A method for simulation of the roller compaction process using a laboratory scale compaction simulator was developed. The simulation was evaluated using microcrystalline cellulose as model material and ribbon solid fraction and tensile strength as key ribbon properties. When compacted to the same solid fractions, real and simulated ribbons exhibited similar compression behavior and equivalent mechanical properties (tensile strengths). Thus, simulated and real ribbons are expected to result in equivalent granulations. Although the simulation cannot account for some roller compaction aspects (non-homogeneous ribbon density and material bypass) it enables prediction of the effects that critical parameters such as roll speed, pressure and radius have on the properties of ribbons using a fraction of material required by conventional roller compaction equipment. Furthermore, constant ribbon solid fraction and/or tensile strength may be utilized as scale up and transfer factors for the roller compaction process. The improved material efficiency and product transfer methods could enable formulation of tablet dosage forms earlier in drug product development. PMID:14706252

  18. Compact stars and the symmetry energy

    NASA Astrophysics Data System (ADS)

    Providência, Constana; Cavagnoli, Rafael; Menezes, Debora P.; Panda, Prafulla K.; Rabhi, Aziz

    2013-02-01

    The effect of the symmetry energy on some properties of compact stars which contain strange degrees of freedom is discussed. Both the onset of hyperons or kaon condensation will be considered. The hyperon-meson couplings are chosen according to experimental values of the hyperon nuclear matter potentials and possible uncertainties are considered. It is shown that a softer symmetry energy affects the onset of strangeness, namely neutral (negatively charged) strange particles set on at larger (smaller) densities, and gives rise to a smaller strangeness fraction as a function of density. A softer symmetry energy will possibily give rise to maximum mass configurations with larger masses. Hyperon-meson couplings have a strong effect on the mass of the star. It is shown that, for stars with masses above 1 Msolar, the radius of the star varies linearly with the symmetry energy slope L.

  19. Collective Deceleration: Toward a Compact Beam Dump

    SciTech Connect

    Wu, H.-C.; Tajima, T.; Habs, D.; Chao, A.W.; 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.

  20. Compact Grism Spectrometer

    NASA Astrophysics Data System (ADS)

    Teare, S. W.

    2003-05-01

    Many observatories and instrument builders are retrofitting visible and near-infrared spectrometers into their existing imaging cameras. Camera designs that reimage the focal plane and have the optical filters located in a pseudo collimated beam are ideal candidates for the addition of a spectrometer. One device commonly used as the dispersing element for such spectrometers is a grism. The traditional grism is constructed from a prism that has had a diffraction grating applied on one surface. The objective of such a design is to use the prism wedge angle to select the desired "in-line" or "zero-deviation" wavelength that passes through on axis. The grating on the surface of the prism provides much of the dispersion for the spectrometer. A grism can also be used in a "constant-dispersion" design which provides an almost linear spatial scale across the spectrum. In this paper we provide an overview of the development of a grism spectrometer for use in a near infrared camera and demonstrate that a compact grism spectrometer can be developed on a very modest budget that can be afforded at almost any facility. The grism design was prototyped using visible light and then a final device was constructed which provides partial coverage in the near infrared I, J, H and K astronomical bands using the appropriate band pass filter for order sorting. The near infrared grism presented here provides a spectral resolution of about 650 and velocity resolution of about 450 km/s. The design of this grism relied on a computer code called Xspect, developed by the author, to determine the various critical parameters of the grism. This work was supported by a small equipment grant from NASA and administered by the AAS.

  1. Compact, Reliable EEPROM Controller

    NASA Technical Reports Server (NTRS)

    Katz, Richard; Kleyner, Igor

    2010-01-01

    A compact, reliable controller for an electrically erasable, programmable read-only memory (EEPROM) has been developed specifically for a space-flight application. The design may be adaptable to other applications in which there are requirements for reliability in general and, in particular, for prevention of inadvertent writing of data in EEPROM cells. Inadvertent writes pose risks of loss of reliability in the original space-flight application and could pose such risks in other applications. Prior EEPROM controllers are large and complex and do not provide all reasonable protections (in many cases, few or no protections) against inadvertent writes. In contrast, the present controller provides several layers of protection against inadvertent writes. The controller also incorporates a write-time monitor, enabling determination of trends in the performance of an EEPROM through all phases of testing. The controller has been designed as an integral subsystem of a system that includes not only the controller and the controlled EEPROM aboard a spacecraft but also computers in a ground control station, relatively simple onboard support circuitry, and an onboard communication subsystem that utilizes the MIL-STD-1553B protocol. (MIL-STD-1553B is a military standard that encompasses a method of communication and electrical-interface requirements for digital electronic subsystems connected to a data bus. MIL-STD- 1553B is commonly used in defense and space applications.) The intent was to both maximize reliability while minimizing the size and complexity of onboard circuitry. In operation, control of the EEPROM is effected via the ground computers, the MIL-STD-1553B communication subsystem, and the onboard support circuitry, all of which, in combination, provide the multiple layers of protection against inadvertent writes. There is no controller software, unlike in many prior EEPROM controllers; software can be a major contributor to unreliability, particularly in fault situations such as the loss of power or brownouts. Protection is also provided by a powermonitoring circuit.

  2. Compact dc link

    SciTech Connect

    Flairty, C. )

    1991-10-01

    The EPRI Compact Substation Project (a HVDC Converter Station) was developed, designed, and constructed per EPRI Agreement RP213. In December 1983, the converter station operated at its rating (100 MW power transmission and 300 kV dc bias plus 100 kV operating voltage). From January to May 1984, the converter station operated at various power transmission levels. Operation was intermittent due to a randomly occurring voltage breakdown. The voltage breakdown was isolated to the steel tanks containing the thyristor valves in an SF{sub 6} environment. The type of insulators stressed within the valve tanks were: (1) the epoxy cone shape insulators providing an interface to the bus entering the valve tank; (2) epoxy fiberglass hydraulic columns for the flow of the R113 refrigerant to and from the thyristor valves; and (3) the epoxy fiberglass support columns supporting the thyristor valves from the floor of the valve tank. The cause of the randomly occurring breakdown was investigated and determined to be the epoxy fiberglass support columns. The random dielectric breakdowns were due to excessive voltage gradients existing at the epoxy fiberglass support columns. This probably was caused by the misplacement of an internal insert within the column with respect to an external shield on the column. The cost and time to retrofit the support columns outweighed the benefits expected from resuming the project. Consequently, work was terminated and the equipment disassembled. Examination of the epoxy fiberglass support columns revealed several arcing tracks along the inside surface confirming the earlier hypothesis. 53 figs., 32 tabs.

  3. Compact Holographic Data Storage

    NASA Astrophysics Data System (ADS)

    Chao, T. H.; Reyes, G. F.; Zhou, H.

    2001-01-01

    NASA's future missions would require massive high-speed onboard data storage capability to Space Science missions. For Space Science, such as the Europa Lander mission, the onboard data storage requirements would be focused on maximizing the spacecraft's ability to survive fault conditions (i.e., no loss in stored science data when spacecraft enters the 'safe mode') and autonomously recover from them during NASA's long-life and deep space missions. This would require the development of non-volatile memory. In order to survive in the stringent environment during space exploration missions, onboard memory requirements would also include: (1) survive a high radiation environment (1 Mrad), (2) operate effectively and efficiently for a very long time (10 years), and (3) sustain at least a billion write cycles. Therefore, memory technologies requirements of NASA's Earth Science and Space Science missions are large capacity, non-volatility, high-transfer rate, high radiation resistance, high storage density, and high power efficiency. JPL, under current sponsorship from NASA Space Science and Earth Science Programs, is developing a high-density, nonvolatile and rad-hard Compact Holographic Data Storage (CHDS) system to enable large-capacity, high-speed, low power consumption, and read/write of data in a space environment. The entire read/write operation will be controlled with electrooptic mechanism without any moving parts. This CHDS will consist of laser diodes, photorefractive crystal, spatial light modulator, photodetector array, and I/O electronic interface. In operation, pages of information would be recorded and retrieved with random access and high-speed. The nonvolatile, rad-hard characteristics of the holographic memory will provide a revolutionary memory technology meeting the high radiation challenge facing the Europa Lander mission. Additional information is contained in the original extended abstract.

  4. 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.

  5. A compact electron spectrometer for an LWFA.

    SciTech Connect

    Lumpkin, A.; Crowell, R.; Li, Y.; Nemeth, K.

    2007-01-01

    The use of a laser wakefield accelerator (LWFA) beam as a driver for a compact free-electron laser (FEL) has been proposed recently. A project is underway at Argonne National Laboratory (ANL) to operate an LWFA in the bubble regime and to use the quasi-monoenergetic electron beam as a driver for a 3-m-long undulator for generation of sub-ps UV radiation. The Terawatt Ultrafast High Field Facility (TUHFF) in the Chemistry Division provides the 20-TW peak power laser. A compact electron spectrometer whose initial fields of 0.45 T provide energy coverage of 30-200 MeV has been selected to characterize the electron beams. The system is based on the Ecole Polytechnique design used for their LWFA and incorporates the 5-cm-long permanent magnet dipole, the LANEX scintillator screen located at the dispersive plane, a Roper Scientific 16-bit MCP-intensified CCD camera, and a Bergoz ICT for complementary charge measurements. Test results on the magnets, the 16-bit camera, and the ICT will be described, and initial electron beam data will be presented as available. Other challenges will also be addressed.

  6. What Is Business's Social Compact?

    ERIC Educational Resources Information Center

    Avishai, Bernard

    1994-01-01

    Under the "new" social compact, businesses must focus on continuous learning and thus have both an obligation to support teaching and an opportunity to profit from it. Learning organizations must also be teaching organizations. (SK)

  7. Mesoscale Simulations of Powder Compaction

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya.; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-01

    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.

  8. A Compact Beam Measurement Setup

    NASA Astrophysics Data System (ADS)

    Graf, Urs U.

    2016-03-01

    We present the design of a compact measurement device to determine the position of a beam in a radio optical setup. The unit is used to align the Terahertz optics of the GREAT instrument on the airborne astronomical observatory SOFIA.

  9. An isolated compact galaxy triplet

    NASA Astrophysics Data System (ADS)

    Feng, Shuai; Shao, Zheng-Yi; Shen, Shi-Yin; Argudo-Fernández, Maria; Wu, Hong; Lam, Man-I.; Yang, Ming; Yuan, Fang-Ting

    2016-05-01

    We report the discovery of an isolated compact galaxy triplet SDSS J084843.45+164417.3, which is first detected by the LAMOST spectral survey and then confirmed by a spectroscopic observation of the BFOSC mounted on the 2.16 meter telescope located at Xinglong Station, which is administered by National Astronomical Observatories, Chinese Academy of Sciences. It is found that this triplet is an isolated and extremely compact system, which has an aligned configuration and very small radial velocity dispersion. The member galaxies have similar colors and show marginal star formation activities. These results support the opinion that the compact triplets are well-evolved systems rather than hierarchically forming structures. This serendipitous discovery reveals the limitations of fiber spectral redshift surveys in studying such a compact system, and demonstrates the necessity of additional observations to complete the current redshift sample.

  10. A compact rotary vane attenuator

    NASA Technical Reports Server (NTRS)

    Nixon, D. L.; Otosh, T. Y.; Stelzried, C. T.

    1969-01-01

    Rotary vane attenuator, when used as a front end attenuator, introduces an insertion loss that is proportional to the angle of rotation. New technique allows the construction of a shortened compact unit suitable for most installations.

  11. Compact Ho:YLF Laser

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1988-01-01

    Longitudinal pumping by laser diodes increases efficiency. Improved holmium:yttrium lithium fluoride laser radiates as much as 56 mW of power at wavelength of 2.1 micrometer. New Ho:YLF laser more compact and efficient than older, more powerful devices of this type. Compact, efficient Ho:YLF laser based on recent successes in use of diode lasers to pump other types of solid-state lasers.

  12. A Compact Polarization Imager

    NASA Technical Reports Server (NTRS)

    Thompson, Karl E.; Rust, David M.; Chen, Hua

    1995-01-01

    A new type of image detector has been designed to analyze the polarization of light simultaneously at all picture elements (pixels) in a scene. The Integrated Dual Imaging Detector (IDID) consists of a polarizing beamsplitter bonded to a custom-designed charge-coupled device with signal-analysis circuitry, all integrated on a silicon chip. The IDID should simplify the design and operation of imaging polarimeters and spectroscopic imagers used, for example, in atmospheric and solar research. Other applications include environmental monitoring and robot vision. Innovations in the IDID include two interleaved 512 x 1024 pixel imaging arrays (one for each polarization plane), large dynamic range (well depth of 10(exp 6) electrons per pixel), simultaneous readout and display of both images at 10(exp 6) pixels per second, and on-chip analog signal processing to produce polarization maps in real time. When used with a lithium niobate Fabry-Perot etalon or other color filter that can encode spectral information as polarization, the IDID can reveal tiny differences between simultaneous images at two wavelengths.

  13. Non-Compact Cardiomyopathy or Ventricular Non-Compact Syndrome?

    PubMed Central

    2014-01-01

    Ventricular myocardial non-compaction has been recognized and defined as a genetic cardiomyopathy by American Heart Association since 2006. The argument on the nomenclature and pathogenesis of this kind of ventricular myocardial non-compaction characterized by regional ventricular wall thickening and deep trabecular recesses often complicated with chronic heart failure, arrhythmia and thromboembolism and usually overlap the genetics and phenotypes of other kind of genetic or mixed cardiomyopathy still exist. The proper classification and correct nomenclature of the non-compact ventricles will contribute to the precisely and completely understanding of etiology and its related patho-physiological mechanism for a better risk stratification and more personalized therapy of the disease individually. All of the genetic heterogeneity and phenotypical overlap and the variety in histopathological, electromechanical and clinical presentation indicates that some of the cardiomyopathies might just be the different consequence of myocardial development variations related to gene mutation and phenotype of one or group genes induced by the interacted and disturbed process of gene modulation at different links of gene function expression and some other etiologies. This review aims to establish a new concept of "ventricular non-compaction syndrome" based on the demonstration of the current findings of etiology, epidemiology, histopathology and echocardiography related to the disorder of ventricular myocardial compaction and myocardial electromechanical function development. PMID:25580189

  14. Directional Oscillations, Concentrations, and Compensated Compactness via Microlocal Compactness Forms

    NASA Astrophysics Data System (ADS)

    Rindler, Filip

    2015-01-01

    This work introduces microlocal compactness forms (MCFs) as a new tool to study oscillations and concentrations in L p -bounded sequences of functions. Decisively, MCFs retain information about the location, value distribution, and direction of oscillations and concentrations, thus extending at the same time the theories of (generalized) Young measures and H-measures. In L p -spaces oscillations and concentrations precisely discriminate between weak and strong compactness, and thus MCFs allow one to quantify the difference in compactness. The definition of MCFs involves a Fourier variable, whereby differential constraints on the functions in the sequence can also be investigated easily—a distinct advantage over Young measure theory. Furthermore, pointwise restrictions are reflected in the MCF as well, paving the way for applications to Tartar's framework of compensated compactness; consequently, we establish a new weak-to-strong compactness theorem in a "geometric" way. After developing several aspects of the abstract theory, we consider three applications; for lamination microstructures, the hierarchy of oscillations is reflected in the MCF. The directional information retained in an MCF is harnessed in the relaxation theory for anisotropic integral functionals. Finally, we indicate how the theory pertains to the study of propagation of singularities in certain systems of PDEs. The proofs combine measure theory, Young measures, and harmonic analysis.

  15. Natural examples of Valdivia compact spaces

    NASA Astrophysics Data System (ADS)

    Kalenda, Ondrej F. K.

    2008-04-01

    We collect examples of Valdivia compact spaces, their continuous images and associated classes of Banach spaces which appear naturally in various branches of mathematics. We focus on topological constructions generating Valdivia compact spaces, linearly ordered compact spaces, compact groups, L1 spaces, Banach lattices and noncommutative L1 spaces.

  16. Modelling of compaction in planetesimals

    NASA Astrophysics Data System (ADS)

    Neumann, Wladimir; Breuer, Doris; Spohn, Tilman

    2014-07-01

    Aims: Compaction of initially porous material prior to melting is an important process that has influenced the interior structure and the thermal evolution of planetesimals in their early history. On the one hand, compaction decreases the porosity resulting in a reduction of the radius and on the other hand, the loss of porosity results in an increase of the thermal conductivity of the material and thus in a more efficient cooling. Porosity loss by hot pressing is the most efficient process of compaction in planetesimals and can be described by creep flow, which depends on temperature and stress. Hot pressing has been repeatedly modelled using a simplified approach, for which the porosity is gradually reduced in some fixed temperature interval between ≈650 K and 700 K. This approach neglects the dependence of compaction on stress and other factors such as matrix grain size and creep activation energy. In the present study, we compare this parametrised method with a self-consistent calculation of porosity loss via a creep related approach. Methods: We use our thermal evolution model from previous studies to model compaction of an initially porous body and consider four basic packings of spherical dust grains (simple cubic, orthorhombic, rhombohedral, and body-centred cubic). Depending on the grain packing, we calculate the effective stress and the associated porosity change via the thermally activated creep flow. For comparison, compaction is also modelled by simply reducing the initial porosity linearly to zero between 650 K and 700 K. As we are interested in thermal metamorphism and not melting, we only consider bodies that experience a maximum temperature below the solidus temperature of the metal phase. Results: For the creep related approach, the temperature interval in which compaction takes place depends strongly on the size of the planetesimal and is not fixed as assumed in the parametrised approach. Depending on the radius, the initial grain size, the activation energy, and the initial porosity and specific packing of the dust grains, the temperature interval lies within 500-1000 K. This finding implies that the parametrised approach strongly overestimates compaction and underestimates the maximum temperature. For the cases considered, the post-compaction porous layer retained at the surface is a factor of 1.5 to 4 thicker for the creep related approach. The difference in the temperature evolution between the two approaches increases with decreasing radius and the maximum temperature can deviate by over 30% for small bodies. Appendix is available in electronic form at http://www.aanda.org

  17. Blue ellipticals in compact groups

    NASA Technical Reports Server (NTRS)

    Zepf, Stephen E.; Whitmore, Bradley C.

    1990-01-01

    By studying galaxies in compact groups, the authors examine the hypothesis that mergers of spiral galaxies make elliptical galaxies. The authors combine dynamical models of the merger-rich compact group environment with stellar evolution models and predict that roughly 15 percent of compact group ellipticals should be 0.15 mag bluer in B - R color than normal ellipticals. The published colors of these galaxies suggest the existence of this predicted blue population, but a normal distribution with large random errors can not be ruled out based on these data alone. However, the authors have new ultraviolet blue visual data which confirm the blue color of the two ellipticals with blue B - R colors for which they have their own colors. This confirmation of a population of blue ellipticals indicates that interactions are occurring in compact groups, but a blue color in one index alone does not require that these ellipticals are recent products of the merger of two spirals. The authors demonstrate how optical spectroscopy in the blue may distinguish between a true spiral + spiral merger and the swallowing of a gas-rich system by an already formed elliptical. The authors also show that the sum of the luminosity of the galaxies in each group is consistent with the hypothesis that the final stage in the evolution of compact group is an elliptical galaxy.

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

    SciTech Connect

    Hladík, Jan; Stuchlík, Zdeněk E-mail: zdenek.stuchlik@fpf.slu.cz

    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.

  19. Compact orthogonal NMR field sensor

    DOEpatents

    Gerald, II, Rex E.; Rathke, Jerome W.

    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.

  20. Compaction Stress in Fine Powders

    SciTech Connect

    Hurd, A.J.; Kenkre, V.M.; Pease, E.A.; Scott, J.E.

    1999-04-01

    A vexing feature in granular materials compaction is density extrema interior to a compacted shape. Such inhomogeneities can lead to weaknesses and loss of dimensional control in ceramic parts, unpredictable dissolution of pharmaceuticals, and undesirable stress concentration in load-bearing soil. As an example, the centerline density in a cylindrical compact often does not decrease monotonically from the pressure source but exhibits local maxima and minima. Two lines of thought in the literature predict, respectively, diffusive and wavelike propagation of stress. Here, a general memory function approach has been formulated that unifies these previous treatments as special cases; by analyzing a convenient intermediate case, the telegrapher's equation, one sees that local density maxima arise via semidiffusive stress waves reflecting from the die walls and adding constructively at the centerline.

  1. Detonation performance of high-dense BTF charges

    NASA Astrophysics Data System (ADS)

    Dolgoborodov, Alexander; Brazhnikov, Michael; Makhov, Michael; Gubin, Sergey; Maklasova, Irina

    2013-06-01

    New experimental data on detonation wave parameters and explosive performance for benzotrifuroxan (BTF) are presented. Optical pyrometry was applied in order to measure the temperature and pressure of BTF detonation products. Chapman-Jouguet pressure and temperature were obtained as following: 33.8 GPa and 3990 K; 34.5 GPa and 4170 K (initial charge densities 1.82 and 1.84 g/cc respectively), the polytropic exponent was estimated as 2.8. The heat of explosion and acceleration ability were measured also. The results of calorimetric measurements performed in bomb calorimeter indicate that BTF slightly surpasses HMX in the heat of explosion. However BTF is inferior to HMX in the acceleration ability, measured by the method of copper casing expansion. It is also considered the hypothesis of formation of nanocarbon particles in detonation products directly behind the detonation front and influence of this processes on the temperature-time history in detonation products. The results of calculations with in view of formation of liquid nanocarbon in products of a detonation also are presented.

  2. Compact accelerator for medical therapy

    DOEpatents

    Caporaso, George J.; Chen, Yu-Jiuan; Hawkins, Steven A.; Sampayan, Stephen E.; Paul, Arthur C.

    2010-05-04

    A compact accelerator system having an integrated particle generator-linear accelerator with a compact, small-scale construction capable of producing an energetic (.about.70-250 MeV) proton beam or other nuclei and transporting the beam direction to a medical therapy patient without the need for bending magnets or other hardware often required for remote beam transport. The integrated particle generator-accelerator is actuable as a unitary body on a support structure to enable scanning of a particle beam by direction actuation of the particle generator-accelerator.

  3. VARIABLE MOMENTUM COMPACTION LATTICE STUDIES.

    SciTech Connect

    KRAMER,S.; MURPHY,J.B.

    1999-03-29

    The VUV storage ring at the National Synchrotron Light Source was used to study the impact of changes in the momentum compaction factors over a large range from positive to negative values. Changes in bunch length and synchrotron tune were measured versus current and RF parameters for these different lattices. By controlling both the first and second-order momentum compaction factors, a lattice was developed in which a pair of alpha buckets was created within the energy aperture of the vacuum chamber and beam was stored simultaneously in both buckets.

  4. Modeling of compact loop antennas

    NASA Astrophysics Data System (ADS)

    Baity, F. W.

    1987-09-01

    A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively tuned resonant double loop (RDL) antennas, the model treats sub-tuned RDL antennas. Calculations using the model have been compared with measurements on full-scale mock-ups of RDL antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and the Compact Ignition Tokamak (CIT).

  5. Compact intermediates in RNA folding

    SciTech Connect

    Woodson, S.A.

    2011-12-14

    Large noncoding RNAs fold into their biologically functional structures via compact yet disordered intermediates, which couple the stable secondary structure of the RNA with the emerging tertiary fold. The specificity of the collapse transition, which coincides with the assembly of helical domains, depends on RNA sequence and counterions. It determines the specificity of the folding pathways and the magnitude of the free energy barriers to the ensuing search for the native conformation. By coupling helix assembly with nascent tertiary interactions, compact folding intermediates in RNA also play a crucial role in ligand binding and RNA-protein recognition.

  6. 75 FR 62568 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-12

    ... of the Council should notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr. Gary S..., FBI Compact Officer, Compact Council Office, Module D3, 1000 Custer Hollow Road, Clarksburg,...

  7. 76 FR 66326 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-26

    ... address this session of the Council should notify the Federal Bureau Of Investigation (FBI) Compact..., FBI Compact Officer, Compact Council Office, Module D3, 1000 Custer Hollow Road, Clarksburg,...

  8. Preparation of ultra-thin and high-quality WO3 compact layers and comparision of WO3 and TiO2 compact layer thickness in planar perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jincheng; Shi, Chengwu; Chen, Junjun; Wang, Yanqing; Li, Mingqian

    2016-06-01

    In this paper, the ultra-thin and high-quality WO3 compact layers were successfully prepared by spin-coating-pyrolysis method using the tungsten isopropoxide solution in isopropanol. The influence of WO3 and TiO2 compact layer thickness on the photovoltaic performance of planar perovskite solar cells was systematically compared, and the interface charge transfer and recombination in planar perovskite solar cells with TiO2 compact layer was analyzed by electrochemical impedance spectroscopy. The results revealed that the optimum thickness of WO3 and TiO2 compact layer was 15 nm and 60 nm. The planar perovskite solar cell with 15 nm WO3 compact layer gave a 9.69% average and 10.14% maximum photoelectric conversion efficiency, whereas the planar perovskite solar cell with 60 nm TiO2 compact layer achieved a 11.79% average and 12.64% maximum photoelectric conversion efficiency.

  9. ULTRA-COMPACT ACCELERATOR TECHNOLOGIES FOR APPLICATION IN NUCLEAR TECHNIQUES

    SciTech Connect

    Sampayan, S; Caporaso, G; Chen, Y; Carazo, V; Falabella, S; Guethlein, G; Guse, S; Harris, J R; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Paul, A C; Pearson, D; Poole, B; Schmidt, R; Sanders, D; Selenes, K; Sitaraman, S; Sullivan, J; Wang, L; Watson, J

    2009-06-11

    We report on compact accelerator technology development for potential use as a pulsed neutron source quantitative post verifier. The technology is derived from our on-going compact accelerator technology development program for radiography under the US Department of Energy and for a clinic sized compact proton therapy systems under an industry sponsored Cooperative Research and Development Agreement. The accelerator technique relies on the synchronous discharge of a prompt pulse generating stacked transmission line structure with the beam transit. The goal of this technology is to achieve {approx}10 MV/m gradients for 10s of nanoseconds pulses and to {approx}100 MV/m gradients for {approx}1 ns systems. As a post verifier for supplementing existing x-ray equipment, this system can remain in a charged, stand-by state with little or no energy consumption. We detail the progress of our overall component development effort with the multilayer dielectric wall insulators (i.e., the accelerator wall), compact power supply technology, kHz repetition-rate surface flashover ion sources, and the prompt pulse generation system consisting of wide-bandgap switches and high performance dielectric materials.

  10. 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.

  11. Upwind Compact Finite Difference Schemes

    NASA Astrophysics Data System (ADS)

    Christie, I.

    1985-07-01

    It was shown by Ciment, Leventhal, and Weinberg ( J. Comput. Phys.28 (1978), 135) that the standard compact finite difference scheme may break down in convection dominated problems. An upwinding of the method, which maintains the fourth order accuracy, is suggested and favorable numerical results are found for a number of test problems.

  12. Mesoscale simulations of powder compaction

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Antoun, Tarabay; Liu, Benjamin

    2009-06-01

    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 experimental match 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 evidence of hard-to-explain reshock states above the single-shock Hugoniot line, which have also been observed in the experiments. We found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations, since 2D results tend to underpredict stress levels for high-porosity powders regardless of material properties. We developed a process to extract macroscale information for the simulation which can be directly used in calibration of continuum model for heterogeneous media.

  13. Laser driven compact ion accelerator

    DOEpatents

    Tajima, Toshiki

    2005-03-15

    A laser driven compact ion source including a light source that produces an energy pulse, a light source guide that guides the energy pulse to a target and produces an ion beam. The ion beam is transported to a desired destination.

  14. 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…

  15. Properties of dynamically compacted WIPP salt

    SciTech Connect

    Brodsky, N.S.; Hansen, F.D.; Pfeifle, T.W.

    1996-07-01

    Dynamic compaction of mine-run salt is being investigated for the Waste Isolation Pilot Plant (WIPP), where compacted salt is being considered for repository sealing applications. One large-scale and two intermediate-scale dynamic compaction demonstrations were conducted. Initial fractional densities of the compacted salt range form 0.85 to 0.90, and permeabilities vary. Dynamically-compacted specimens were further consolidated in the laboratory by application of hydrostatic pressure. Permeability as a function of density was determined, and consolidation microprocesses were studied. Experimental results, in conjunction with modeling results, indicate that the compacted salt will function as a viable seal material.

  16. Compaction in the Bushveld Complex

    NASA Astrophysics Data System (ADS)

    Boorman, S.; Boudreau, A.

    2003-12-01

    Compaction in the mush zone of a crystallizing chamber is a model for fractionation, whereby evolved interstitial liquid expelled from the compacting crystal pile is returned to the magma chamber. If compaction was important during crystallization of the Lower and Critical Zones of the Bushveld Complex, certain textural features are expected; and, these features should correlate to position in the section, as well as to the number of mineral phases present. We report on a spectrum of textural data for 30 samples form the Lower and Critical Zones of the Bushveld Complex. Crystal Size Distributions (CSDs) are a semi-log plot of population density against crystal size, and provide information about magmatic processes such as crystal accumulation, removal and aging. Changes to the magmatic system are reflected in the shape of the CSD plot. CSDs of Bushveld rocks show a log-linear trend overturned at smaller grain sizes, a result consistent with both crystal aging, wherein larger grains grow at the expense of small ones in the crystallizing pile, and melt migration, where nucleation is suppressed by the loss of late melt fractions. CSD slope and intercept data vary with stratigraphy. Slopes in the Critical Zone are steeper, indicating less recrystallization and less of a compaction effect. In contrast, slopes in the Lower Zone are shallower, a result consistent with slower cooling and a greater compaction/recrystallization effect. Likewise, lower CSD intercepts are associated with the shallower slopes of the lower zone and vice versa. The extent of foliation is measured as alignment factor (AF), determined by orientation statistics of the major axes of the grains of interest. AF decreases with stratigraphic height and foliation is best developed in the nearly monomineralic harzburgite of the Lower Zone (AF avg=64). At the Lower Zone-Critical Zone transition, plagioclase content increases, decreasing bulk density and thus, the systems ability to accommodate compaction (Upper Critical Zone AF avg=57). There is a positive correlation between the quality of the foliation and mineral aspect ratio, suggesting that recrystallization (crystal aging) demonstrated by CSD plots occurred in a regime of uniaxial stress, wherein selective grain resorption of unfavorably oriented grains and uneven crystal growth results in grains with high aspect ratios. Spatial distribution pattern (SDP) analysis is used to determine the framework structure of spheres in 3-D. Results of R-value analysis (based on nearest neighbor statistics, (Jerram et al., 1996)) are plotted against porosity to compare Bushveld data against fields for touching and non-touching framework structures, and clustered v. ordered crystal distributions. As the Bushveld minerals are not spheres, the applicability of the field boundaries is questionable. Bushveld data form a trend that is coincident with the trend defined either by variable extents of size sorting or by the deformational compaction of spheres. A correlation on a plot of R-value versus aspect ratio clarifies that trend observed on the spatial distribution plot is due to deformational compaction. Phosphorous is a proxy for trapped liquid fraction because it is incompatible in all major phases: it indicates the extent to which late melt has been expelled. Depletion of P in the Lower Zone, where mineral alignment is highest and compaction most efficient, agrees with the hypothesis that compaction was important in redistributing trace elements. Residual porosity calculations based on Y show porosity of 5% in the Lower Zone and 20% in the Upper Critical Zone. R-values plotted against the residual porosity produce a positive trend, relating decreased porosity to grain distribution. Jerram et al., 1996 Contrib. Min. Pet. 125, 60-74.

  17. 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.

  18. Scaling Theory for Percolative Charge Transport in Disordered Molecular Semiconductors

    NASA Astrophysics Data System (ADS)

    Cottaar, J.; Koster, L. J. A.; Coehoorn, R.; Bobbert, P. A.

    2011-09-01

    We present a scaling theory for charge transport in disordered molecular semiconductors that extends percolation theory by including bonds with conductances close to the percolating one in the random-resistor network representing charge hopping. A general and compact expression is given for the charge mobility for Miller-Abrahams and Marcus hopping on different lattices with Gaussian energy disorder, with parameters determined from numerically exact results. The charge-concentration dependence is universal. The model-specific temperature dependence can be used to distinguish between the hopping models.

  19. Tank farms compacted low level waste

    SciTech Connect

    Waters, M.S., Westinghouse Hanford

    1996-07-01

    This report describes the process of Low Level Waste (LLW) volume reduction by compaction. Also included is the data used for characterization of LLW destined for compaction. Scaling factors (ratios) are formed based on data contained in this report.

  20. Invariant distributions on compact homogeneous spaces

    SciTech Connect

    Gorbatsevich, V V

    2013-12-31

    In this paper, we study distributions on compact homogeneous spaces, including invariant distributions and also distributions admitting a sub-Riemannian structure. We first consider distributions of dimension 1 and 2 on compact homogeneous spaces. After this, we study the cases of compact homogeneous spaces of dimension 2, 3, and 4 in detail. Invariant distributions on simply connected compact homogeneous spaces are also treated. Bibliography: 18 titles.

  1. On phenomenology of compact intracloud lightning discharges

    NASA Astrophysics Data System (ADS)

    Nag, Amitabh; Rakov, Vladimir A.; Tsalikis, Dimitris; Cramer, John A.

    2010-07-01

    We examined wideband electric fields, electric and magnetic field derivatives, and narrowband VHF (36 MHz) radiation bursts produced by 157 compact intracloud discharges (CIDs). These poorly understood lightning events appear to be the strongest natural producers of HF-VHF radiation. All the events transported negative charge upward (or lowered positive charge), 150 were located by the U.S. National Lightning Detection Network (NLDN), and 149 of them were correctly identified as cloud discharges. NLDN-reported distances from the measurement station were 5-132 km. Three types of wideband electric field waveforms were observed. About 73% of CIDs occurred in isolation; 24% occurred prior to, during, or following cloud-to-ground or "normal" cloud lightning; and 4% occurred in pairs, separated by less than 200 ms ("multiple" CIDs). For a subset of 48 CIDs, the geometric mean of radiation source height was estimated to be 16 km. It appears that some CIDs actually occurred above cloud tops in clear air or in convective surges (plumes) overshooting the tropopause and penetrating deep into the stratosphere. For the same 48 CIDs, the geometric mean electric field peak normalized to 100 km (inclined distance) was as high as 20 V/m, and for 22 events within 10-30 km (horizontal distance), it was 15 V/m, both of which are higher than that for first strokes in negative cloud-to-ground lightning. The geometric means of total electric field pulse duration, width of initial half cycle, and ratio of initial peak to opposite polarity overshoot were 23 μs, 5.6 μs, and 5.7, respectively.

  2. Compact torus studies: Final report

    SciTech Connect

    Morse, E.C.

    1987-06-01

    The compact torus (CT) device has been proposed for use in some applications which are of interest in Laboratory programs in the areas of pulsed power and inertial confinement fusion. These applications involve compression and acceleration of CT plasmas. The RACE (Ring Accelerator Experiment) experimental program at Livermore has been initiated to study these applications. The work reported here involves studies of plasma physics and other aspects of these compact torus applications. The studies conducted identify specific problem areas associated with the CT device and examine these areas in some detail. This report contains studies of three particular problem areas of the CT applications. These three areas are: the general nonlinear properties of the CT as a magnetohydrodynamic (MHD) equilibrium, particle simulation of the compression of the CT, with a focus on the non-MHD effects, and nonlinear RF interaction problems in the CT.

  3. 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

  4. Rapid compaction during RNA folding

    NASA Astrophysics Data System (ADS)

    Russell, Rick; Millett, Ian S.; Tate, Mark W.; Kwok, Lisa W.; Nakatani, Bradley; Gruner, Sol M.; Mochrie, Simon G. J.; Pande, Vijay; Doniach, Sebastian; Herschlag, Daniel; Pollack, Lois

    2002-04-01

    We have used small angle x-ray scattering and computer simulations with a coarse-grained model to provide a time-resolved picture of the global folding process of the Tetrahymena group I RNA over a time window of more than five orders of magnitude. A substantial phase of compaction is observed on the low millisecond timescale, and the overall compaction and global shape changes are largely complete within one second, earlier than any known tertiary contacts are formed. This finding indicates that the RNA forms a nonspecifically collapsed intermediate and then searches for its tertiary contacts within a highly restricted subset of conformational space. The collapsed intermediate early in folding of this RNA is grossly akin to molten globule intermediates in protein folding.

  5. The Design of a Compact Rfq Neutron Generator

    NASA Astrophysics Data System (ADS)

    Hamm, R. W.; Becker, R.

    2014-02-01

    The output and target lifetime of a conventional electrostatic neutron generator are limited by the voltage stand-off capability and the acceleration of molecular species from the ion source. As an alternative, we suggest that the deuterium beam achievable from a compact high intensity ECR source can be injected directly into a compact RFQ to produce a more efficient compact neutron production system. Only the d+ ions are accelerated by the RFQ, which can also produce much higher output energies than electrostatic systems, resulting in a higher neutron output with a longer target lifetime. The direct injection of the beam makes the system more compact than the multielement, electrostatic systems typically used for extraction of the beam and subsequent transport and matching into the RFQ. We have designed and optimized a combined extraction/matching system for a compact high current deuterium ECR ion source injected into a high frequency RFQ structure, allowing a beam of about 12 mA of d+ ions to be injected at a modest ion source voltage of 25 kV. The end wall of the RFQ resonator serves as the ground electrode for the ion source, resembling DPI (direct plasma injection). For this design, we used the features of the code IGUN to take into account the electrostatic field between the ion source and the RFQ end wall, the stray magnetic field of the ECR source, the defocusing space charge of the low energy deuteron beam, and the rf focusing in the fringe field between the RFQ vanes and the RFQ flange.

  6. 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.

  7. Compact magnetic energy storage module

    DOEpatents

    Prueitt, Melvin L.

    1994-01-01

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

  8. Compact portable diffraction moire interferometer

    DOEpatents

    Deason, V.A.; Ward, M.B.

    1988-05-23

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

  9. Compact portable diffraction moire interferometer

    DOEpatents

    Deason, Vance A.; Ward, Michael B.

    1989-01-01

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

  10. 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.

  11. Nuclear Physics for Compact Stars

    SciTech Connect

    Baldo, M.

    2009-05-04

    A brief overview is given of the different lines of research developed under the INFN project 'Compact Stellar Objects and Dense Hadronic Matter' (acronym CT51). The emphasis of the project is on the structure of Neutron Stars (NS) and related objects. Starting from crust, the different Nuclear Physics problems are described which are encountered going inside a NS down to its inner core. The theoretical challenges and the observational inputs are discussed in some detail.

  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. CIT (Compact Ignition Tokamak) fueling

    SciTech Connect

    Houlberg, W.A.

    1988-01-01

    A series of viewgraphs present issues related to the conceptual design of the Compact Ignition Tokamak. The presentation includes discussions of fueling issues, pellet injector technology, pellet ablation and penetration, particle confinement, and fueling scenarios. The author concludes that existing technology should be used for the basic injector while several options for enhanced velocity injectors are under development; adequate models exist for pellet ablation; and improvements in confinement models can come from the TFTR and JET programs. (DWL)

  14. Compact planar microwave blocking filters

    NASA Technical Reports Server (NTRS)

    U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor)

    2012-01-01

    A compact planar microwave blocking filter includes a dielectric substrate and a plurality of filter unit elements disposed on the substrate. The filter unit elements are interconnected in a symmetrical series cascade with filter unit elements being organized in the series based on physical size. In the filter, a first filter unit element of the plurality of filter unit elements includes a low impedance open-ended line configured to reduce the shunt capacitance of the filter.

  15. Compact optical microfiber phase modulator.

    PubMed

    Zhang, Xueliang; Belal, M; Chen, G Y; Song, Zhangqi; Brambilla, G; Newson, T P

    2012-02-01

    A compact optical microfiber phase modulator with MHz bandwidth is presented. A micrometer-diameter microfiber is wound on a millimeter-diameter piezoelectric ceramic rod with two electrodes. When a voltage is applied to the piezoelectric ceramic, the rod is strained, leading to a phase change along the microfiber; because of the small size, the optical microfiber phase modulator can have as high as a few MHz bandwidth response. PMID:22297339

  16. 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.

  17. 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.

  18. Thixoforming of Stellite Powder Compacts

    SciTech Connect

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

    2007-04-07

    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 deg. C-1350 deg. 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. Compact noninvasive electron bunch-length monitor

    NASA Astrophysics Data System (ADS)

    Roberts, B.; Mammei, R. R.; Poelker, M.; McCarter, J. L.

    2012-12-01

    A compact rf cavity was constructed that simultaneously resonates at many harmonic modes when excited by a repetitive bunched electron beam passing through its bore. The excitation of these modes provides a Fourier description of the temporal characteristics of the bunch train. The cavity was used to noninvasively characterize electron bunches produced from thin and thick GaAs photocathodes inside a DC high voltage photogun illuminated with 37 ps (full width half maximum, FWHM) laser pulses at repetition rates near 1500 MHz, at average beam current from 5 to 500μA, and at beam energy from 75 to 195 keV. The cavity bunch-length monitor could detect electron bunches as short as 57 ps (FWHM) when connected directly to a sampling oscilloscope, and could clearly distinguish bunches with varying degrees of space-charge induced growth and with different tail signatures. Efforts are under way to detect shorter bunches by designing cavities with increased bandwidth. This demonstration lends credibility to the idea that these cavities could also be used for other applications, including bunching and shaping, when driven with external rf.

  20. Electron Strippers for Compact Neutron Generators

    NASA Astrophysics Data System (ADS)

    Terai, K.; Tanaka, N.; Kisaki, M.; Tsugawa, K.; Okamoto, A.; Kitajima, S.; Sasao, M.; Takeno, T.; Antolak, A. J.; Leung, K. N.; Wada, M.

    2011-09-01

    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- to H+ 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- beam was accelerated to about 180 keV, passes through a stripping foil, and produces a mixed beam of H-, H0, and H+. 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- beam was injected onto a metal surface with an oblique angle, and reflected H+ ions are detected. It was found that the conversion efficiency, H+ fraction in the reflected particles, depends on the surface condition, with the maximum value of about 90%.

  1. Collective deceleration: Toward a compact beam dump

    NASA Astrophysics Data System (ADS)

    Wu, H.-C.; Tajima, T.; Habs, D.; Chao, A. W.; Meyer-Ter-Vehn, J.

    2010-10-01

    With the increasing development of laser electron accelerators, electron energies beyond a GeV have been reached and higher values are expected in the near future. A conventional beam dump based on ionization or radiation loss mechanisms is cumbersome and costly, not to mention the radiological hazards. We revisit the stopping power theory of high-energy charged particles in matter and discuss the associated problem of beam dumping from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than that described by the Bethe-Bloch formulas and associated with multiple electromagnetic cascades in solids. At the same time, the tenuous density of the gas makes the radioactivation negligible. Such a compact beam dump without radioactivation works well for short and dense bunches, as they are typically generated from a laser wakefield accelerator. In addition, the nonuniform transverse wakefield can induce microbunching of the electron bunch by betatron oscillation. The microstructure could serve as a prebunched source for coherent radiation or feeding a free electron laser.

  2. Electron Strippers for Compact Neutron Generators

    SciTech Connect

    Terai, K.; Tanaka, N.; Kisaki, M.; Tsugawa, K.; Okamoto, A.; Kitajima, S.; Sasao, M.; Takeno, T.; Antolak, A. J.; Leung, K. N.; Wada, M.

    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%.

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

    SciTech Connect

    Railsback, Justin; Singh, Abhishek; Pearce, Ryan; McKnight, Timothy E; Collazo, Ramon; Sitar, Zlatko; Yingling, Yaroslava; Melechko, Anatoli Vasilievich

    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.

  4. On Intuitionistic Fuzzy β-Almost Compactness and β-Nearly Compactness

    PubMed Central

    Renuka, R.; Seenivasan, V.

    2015-01-01

    The concept of intuitionistic fuzzy β-almost compactness and intuitionistic fuzzy β-nearly compactness in intuitionistic fuzzy topological spaces is introduced and studied. Besides giving characterizations of these spaces, we study some of their properties. Also, we investigate the behavior of intuitionistic fuzzy β-compactness, intuitionistic fuzzy β-almost compactness, and intuitionistic fuzzy β-nearly compactness under several types of intuitionistic fuzzy continuous mappings. PMID:26236774

  5. Simple, compact, high-repetition rate XeCl laser

    NASA Astrophysics Data System (ADS)

    Armandillo, E.; Grasso, G.; Salvetti, G.; Penco, E.

    1985-05-01

    Operation of a compact corona-preionized XeCl excimer laser, simple in construction and utilizing all commercial components, is reported. The laser comprises a stainless-steel-tube vacuum/pressure vessel with a total gas volume of about 4.5 l, an excitation circuit of the capacitor charge transfer type, and two water-cooled copper pipe heat exchangers. An average output power in excess of 1 W was obtained at pulse repetition frequencies (PRF) of up to 750 Hz. A maximum efficiency of 0.15 percent is reported for PRF of 400 at a charging voltage of 25 kV. Finally, considerably longer gas lifetime is noted when helium was used as a buffer gas, as compared with that of neon, yielding a 10-percent reduction in power after more than 1 million firings.

  6. Metastability of hadronic compact stars

    SciTech Connect

    Bombaci, Ignazio; Panda, Prafulla K.; Providencia, Constanca; Vidana, Isaac

    2008-04-15

    Pure hadronic compact stars, above a threshold value of their gravitational mass (central pressure), are metastable to the conversion to quark stars (hybrid or strange stars). In this paper, we present a systematic study of the metastability of pure hadronic compact stars using different relativistic models for the equation of state. In particular, we compare results for the quark-meson coupling model with those for the Glendenning-Moszkowski parametrization of the nonlinear Walecka model. For the quark-meson coupling model, we find large values (M{sub cr}=1.6-1.9M{sub {center_dot}}) for the critical mass of the hadronic star sequence and we find that the formation of a quark star is only possible with a soft quark matter equation of state. For the Glendenning-Moszkowski parametrization of the nonlinear Walecka model, we explore the effect of different hyperon couplings on the critical mass and on the stellar conversion energy. We find that increasing the value of the hyperon coupling constants shifts the bulk transition point for quark deconfinement to higher densities, increases the stellar metastability threshold mass and the value of the critical mass, and thus makes the formation of quark stars less likely. For the largest values of the hyperon couplings we find a critical mass which may be as high as 1.9-2.1M{sub {center_dot}}. These stellar configurations, which contain a large central hyperon fraction (f{sub Y,cr}{approx}30%), would be able to describe highly massive compact stars, such as the one associated with the millisecond pulsar PSR B1516+02B with a mass M=1.94{sub -0.19}{sup +0.17}M{sub {center_dot}}.

  7. 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.

  8. 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.

  9. 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.

  10. Compact integrated optical sensor system.

    PubMed

    Wiki, M; Gao, H; Juvet, M; Kunz, R E

    2001-01-01

    A compact integrated optical sensor system for a large variety of different (bio-) chemical applications using replicated sensor chips is described. Features of the refractometric system to be emphasized for practical applications include a high-resolution window that can be positioned within a wide measuring range, an in situ chip testing and characterization procedure, and on-chip referencing. As an application example, experimental results on refractometric measurements as well as on the suppression of non-specific binding are given. PMID:11261851

  11. 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.

  12. Shock compaction of molybdenum powder

    NASA Technical Reports Server (NTRS)

    Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.

    1983-01-01

    Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.

  13. 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. PMID:26056519

  14. Two Piece Compaction Die Design

    SciTech Connect

    Coffey, Ethan N

    2010-03-01

    Compaction dies used to create europium oxide and tantalum control plates were modeled using ANSYS 11.0. Two-piece designs were considered in order to make the dies easier to assemble than the five-piece dies that were previously used. The two areas of concern were the stresses at the interior corner of the die cavity and the distortion of the cavity wall due to the interference fit between the two pieces and the pressure exerted on the die during the compaction process. A successful die design would have stresses less than the yield stress of the material and a maximum wall distortion on the order of 0.0001 in. Design factors that were investigated include the inner corner radius, the value of the interference fit, the compaction force, the size of the cavity, and the outer radius and geometry of the outer ring. The results show that for the europium oxide die, a 0.01 in. diameter wire can be used to create the cavity, leading to a 0.0055 in. radius corner, if the radial interference fit is 0.003 in. For the tantalum die, the same wire can be used with a radial interference fit of 0.001 in. Also, for the europium oxide die with a 0.003 in. interference fit, it is possible to use a wire with a diameter of 0.006 in. for the wire burning process. Adding a 10% safety factor to the compaction force tends to lead to conservative estimates of the stresses but not for the wall distortion. However, when the 10% safety factor is removed, the wall distortion is not affected enough to discard the design. Finally, regarding the europium oxide die, when the cavity walls are increased by 0.002 in. per side or the outer ring is made to the same geometry as the tantalum die, all the stresses and wall distortions are within the desired range. Thus, the recommendation is to use a 0.006 in. diameter wire and a 0.003 in. interference fit for the europium oxide die and a 0.01 in. diameter wire and a 0.001 in. interference fit for the tantalum die. The dies can also be made to have the same outer geometry if desired.

  15. 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 (μCE). 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.

  16. Compact Video Microscope Imaging System Implemented in Colloid Studies

    NASA Technical Reports Server (NTRS)

    McDowell, Mark

    2002-01-01

    Long description Photographs showing fiber-optic light source, microscope and charge-coupled discharge (CCD) camera head connected to camera body, CCD camera body feeding data to image acquisition board in PC, and Cartesian robot controlled via PC board. The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. CMIS can be used in situ with a minimum amount of user intervention. This system can scan, find areas of interest in, focus on, and acquire images automatically. Many multiple-cell experiments require microscopy for in situ observations; this is feasible only with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control. The software also has a user-friendly interface, which can be used independently of the hardware for further post-experiment analysis. CMIS has been successfully developed in the SML Laboratory at the NASA Glenn Research Center and adapted for use for colloid studies and is available for telescience experiments. The main innovations this year are an improved interface, optimized algorithms, and the ability to control conventional full-sized microscopes in addition to compact microscopes. The CMIS software-hardware interface is being integrated into our SML Analysis package, which will be a robust general-purpose image-processing package that can handle over 100 space and industrial applications.

  17. Compact electron beam ion sources/traps: review and prospects.

    PubMed

    Zschornack, G; Kreller, M; Ovsyannikov, V P; Grossman, F; Kentsch, U; Schmidt, M; Ullmann, F; Heller, R

    2008-02-01

    The Dresden electron beam ion trap (EBIT)/electron beam ion source (EBIS) family are very compact and economically working table-top ion sources. We report on the development of three generations of such ion sources, the so-called Dresden EBIT, Dresden EBIS, and Dresden EBIS-A, respectively. The ion sources are classified by different currents of extractable ions at different charge states and by the x-ray spectra emitted by the ions inside the electron beam. We present examples of x-ray measurements and measured ion currents extracted from the ion sources at certain individual operating conditions. Ion charge states of up to Xe(48+) but also bare nuclei of lighter elements up to nickel have been extracted. The application potential of the ion sources is demonstrated via proof-of-concept applications employing an EBIT in a focused ion beam (FIB) column or using an EBIT for the production of nanostructures by single ion hits. Additionally we give first information about the next generation of the Dresden EBIS series. The so-called Dresden EBIS-SC is a compact and cryogen-free superconducting high-B-field EBIS for high-current operation. PMID:18315151

  18. Intense Pulsed Neutron Emission from a Compact Pyroelectric Driven Accelerator

    SciTech Connect

    Tang, V; Meyer, G; Falabella, S; Guethlein, G; Sampayan, S; Kerr, P; Rusnak, B; Morse, J

    2008-10-08

    Intense pulsed D-D neutron emission with rates >10{sup 10} n/s during the pulse, pulse widths of {approx}100's ns, and neutron yields >10 k per pulse are demonstrated in a compact pyroelectric accelerator. The accelerator consists of a small pyroelectric LiTaO{sub 3} crystal which provides the accelerating voltage and an independent compact spark plasma ion source. The crystal voltage versus temperature is characterized and compare well with theory. Results show neutron output per pulse that scales with voltage as V{approx}1.7. These neutron yields match a simple model of the system at low voltages but are lower than predicted at higher voltages due to charge losses not accounted for in the model. Interpretation of the data against modeling provides understanding of the accelerator and in general pyroelectric LiTaO{sub 3} crystals operated as charge limited negative high voltage targets. The findings overall serve as the proof-of-principle and basis for pyroelectric neutron generators that can be pulsed, giving peak neutron rates orders of magnitude greater than previous work, and notably increase the potential applications of pyroelectric based neutron generators.

  19. The Planck Compact Source Catalogues

    NASA Astrophysics Data System (ADS)

    Lopez-Caniego, Marcos

    2015-12-01

    The Second Planck Catalogue of Compact Sources is a catalogue of sources observed over the entire sky at nine different frequencies between 30 and 857 GHz. It consists of Galactic and extragalactic objects detected in the Planck single-frequency full mission total intensity maps. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two sub·catalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The PCCS2 covers most of the sky and can be used to produce subsamples at higher reliabilities than the target 80% integral reliability of the catalogue. The PCCS2E contains sources located in certain regions where the complex background makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels.

  20. 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.

  1. Compacted carbon for electrochemical cells

    DOEpatents

    Greinke, R.A.; Lewis, I.C.

    1997-10-14

    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: (1) an x-ray density of at least 2.00 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 47%; and (b) graphite having the following properties: (1) an x-ray density of at least 2.20 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) 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 counter electrode. 10 figs.

  2. Compacted carbon for electrochemical cells

    DOEpatents

    Greinke, Ronald Alfred; Lewis, Irwin Charles

    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.

  3. Cold compaction of water ice

    USGS Publications Warehouse

    Durham, W.B.; McKinnon, W.B.; Stern, L.A.

    2005-01-01

    Hydrostatic compaction of granulated water ice was measured in laboratory experiments at temperatures 77 K to 120 K. We performed step-wise hydrostatic pressurization tests on 5 samples to maximum pressures P of 150 MPa, using relatively tight (0.18-0.25 mm) and broad (0.25-2.0 mm) starting grain-size distributions. Compaction change of volume is highly nonlinear in P, typical for brittle, granular materials. No time-dependent creep occurred on the lab time scale. Significant residual porosity (???0.10) remains even at highest P. Examination by scanning electron microscopy (SEM) reveals a random configuration of fractures and broad distribution of grain sizes, again consistent with brittle behavior. Residual porosity appears as smaller, well-supported micropores between ice fragments. Over the interior pressures found in smaller midsize icy satellites and Kuiper Belt objects (KBOs), substantial porosity can be sustained over solar system history in the absence of significant heating and resultant sintering. Copyright 2005 by the American Geophysical Union.

  4. 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.

  5. Structural properties of compact groups

    NASA Technical Reports Server (NTRS)

    De Carvalho, R. R.; Ribeiro, A. L. B.; Zepf, Stephen E.

    1994-01-01

    We report the results of a systematic study of galaxies in the regions of Hickson compact groups. Our sample is composed of the 22 Hickson groups which are located in the southern hemisphere and have cz less than 9000 km/s. Making use of digitized images of IIIa-J plates that cover an area of 0.5 x 0.5 deg around each group, we were able to detect and classify images down to a magnitude limit of 19.5 in the B band. This limit is typically three magnitudes fainter than previous studies. Most groups show a statistically significant excess of fainter galaxies compared to the background. These fainter galaxies typically have a somewhat more extended spatial distribution than the brighter galaxies originally classified by Hickson. Our data suggest that Hickson groups have a wide range in density and radius, ranging from very compact structures with overdensities of the order of 10(exp 2) and crossing times of roughly 0.01 H(sub 0 sup -1), to much more diffuse structures, similar to loose groups, with overdensities of about 3 and crossing times of roughly 0.5 H(sub 0 sup -1).

  6. Incompletely compacted equilibrated ordinary chondrites

    SciTech Connect

    Sasso, M.R.; Macke, R.J.; Boesenberg, J.S.; Britt, D.T.; Rovers, M.L.; Ebel, D.S.; Friedrich, J.M.

    2010-01-22

    We document the size distributions and locations of voids present within five highly porous equilibrated ordinary chondrites using high-resolution synchrotron X-ray microtomography ({mu}CT) and helium pycnometry. We found total porosities ranging from {approx}10 to 20% within these chondrites, and with {mu}CT we show that up to 64% of the void space is located within intergranular voids within the rock. Given the low (S1-S2) shock stages of the samples and the large voids between mineral grains, we conclude that these samples experienced unusually low amounts of compaction and shock loading throughout their entire post accretionary history. With Fe metal and FeS metal abundances and grain size distributions, we show that these chondrites formed naturally with greater than average porosities prior to parent body metamorphism. These materials were not 'fluffed' on their parent body by impact-related regolith gardening or events caused by seismic vibrations. Samples of all three chemical types of ordinary chondrites (LL, L, H) are represented in this study and we conclude that incomplete compaction is common within the asteroid belt.

  7. 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.

  8. Bootstrap current in compact stellarators*

    NASA Astrophysics Data System (ADS)

    Moroz, P. E.; Hirshman, S. P.; Spong, D. A.; Hughes, M.; Monticello, D. A.

    1998-11-01

    Bootstrap current characteristics are investigated for a few novel type compact stellarator configurations with plasma current, including QAS (quasi-axially symmetric), QOS (quasi-omnigenous) and ELARS (extremely low aspect ratio) stellarators. Calculations have been carried out via the modified version of VMEC with an additional module for computing 3D bootstrap current in the collisionless regime (BOOTSJ code). Special attention is given to underlying physics associated with resonance smoothing, to computational characteristics, implementation, and optimization within the VMEC code, as well as to the results produced for various compact stellarators. The results presented correspond to the first iteration in the bootstrap current calculation for an initially given plasma current, and also to the self-consistent calculation of the 3D MHD equilibria in which the bootstrap current provides the only source of the plasma current. Benchmarking of BOOTSJ with the NIFS-BS code (which include finite collisionality effects) will be discussed. A strong dependence of the bootstrap current on configuration characteristics is found, ranging from values almost equal to that in an equivalent tokamak in QAS to over an order of magnitude lower in QOS. *Supported by U.S. Department of Energy

  9. Compact submanifolds supporting singular interactions

    SciTech Connect

    Kaynak, Burak Tevfik Teoman Turgut, O.

    2013-12-15

    A quantum particle moving under the influence of singular interactions on embedded surfaces furnish an interesting example from the spectral point of view. In these problems, the possible occurrence of a bound-state is perhaps the most important aspect. Such systems can be introduced as quadratic forms and generically they do not require renormalization. Yet an alternative path through the resolvent is also beneficial to study various properties. In the present work, we address these issues for compact surfaces embedded in a class of ambient manifolds. We discover that there is an exact bound state solution written in terms of the heat kernel of the ambient manifold for a range of coupling strengths. Moreover, we develop techniques to estimate bounds on the ground state energy when several surfaces, each of which admits a bound state solution, coexist. -- Highlights: •Schrödinger operator with singular interactions supported on compact submanifolds. •Exact bound-state solution in terms of the heat kernel of the ambient manifold. •Generalization of the variational approach to a collection of submanifolds. •Existence of a lower bound for a unique ground state energy.

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

    SciTech Connect

    Suzuki, Hiroyuki Y.

    2008-02-15

    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. Compact pulse forming line using barium titanate ceramic material

    NASA Astrophysics Data System (ADS)

    Kumar Sharma, Surender; Deb, P.; Shukla, R.; Prabaharan, T.; Shyam, A.

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO3) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 Ω load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber.

  13. Compact pulse forming line using barium titanate ceramic material.

    PubMed

    Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. PMID:22129008

  14. Compact Solid State Cooling Systems: Compact MEMS Electrocaloric Module

    SciTech Connect

    2010-10-01

    BEETIT Project: UCLA is developing a novel solid-state cooling technology to translate a recent scientific discovery of the so-called giant electrocaloric effect into commercially viable compact cooling systems. Traditional air conditioners use noisy, vapor compression systems that include a polluting liquid refrigerant to circulate within the air conditioner, absorb heat, and pump the heat out into the environment. Electrocaloric materials achieve the same result by heating up when placed within an electric field and cooling down when removed—effectively pumping heat out from a cooler to warmer environment. This electrocaloric-based solid state cooling system is quiet and does not use liquid refrigerants. The innovation includes developing nano-structured materials and reliable interfaces for heat exchange. With these innovations and advances in micro/nano-scale manufacturing technologies pioneered by semiconductor companies, UCLA is aiming to extend the performance/reliability of the cooling module.

  15. Combined method of compaction of collapsible soils

    SciTech Connect

    Bagdasarov, Yu.A.

    1994-07-01

    The writer proposes a combined method of compaction of collapsible soils. He presents results of investigations carried out to study compacted zones of pads punched (tamped-out) by rammers 10 and 20 tons in mass, as well as a comparative analysis of the pads over against compacted zones obtained by means of plane rammers. The analysis results are illustrated by the {open_quotes}arch effect{close_quotes} on the stress conditions of the soaked soil mass.

  16. 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.

  17. Method for preparing porous metal hydride compacts

    DOEpatents

    Ron, Moshe; Gruen, Dieter M.; Mendelsohn, Marshall H.; Sheft, Irving

    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.

  18. The influence of varying precompaction and main compaction profile parameters on the mechanical strength of compacts.

    PubMed

    Ruegger, C E; Celik, M

    2000-01-01

    The purpose of this work was to investigate how altering the method of force application could be beneficial to tablet production in order to increase tablet strength and eliminate or minimize the incidence of capping and lamination. An integrated compaction research system (i.e., compaction simulator) was used throughout this study. Compaction profiles containing a single compaction event and a double (pre- and main) compaction event were created. The ratio and magnitude of the pre- and main compaction pressures were varied and the time interval between the pre- and main compaction events was altered to determine the effects on the crushing strengths and capping tendency of the final compacts. In all cases, for a given pressure, the double compaction event produced stronger tablets than the single compaction event. When the ratio and magnitude of the pre- and main compaction pressures were varied, the results differed depending on the material undergoing compaction. Dicalcium phosphate/microcrystalline cellulose and pregelatinized starch tablets had no significant difference in crushing strength values regardless of whether the precompaction pressure was less than or greater than the main compaction pressure. However, both direct compression (DC) acetaminophen and DC ibuprofen were found to have increased crushing strengths and decreased capping/lamination when the precompaction pressure was less than the main compaction pressure. When the time interval between the pre- and main compaction events was varied from 30 to 500 msec, no significant difference in the crushing strength or capping/lamination tendency was observed. It was concluded that the effect of altering the ratio and magnitude of the pre- and main compaction pressures varied from one material to another, suggesting that the profiles should be tailored individually for the specific material undergoing compaction. PMID:11109249

  19. Chromosome Compaction by Active Loop Extrusion.

    PubMed

    Goloborodko, Anton; Marko, John F; Mirny, Leonid A

    2016-05-24

    During cell division, chromosomes are compacted in length by more than a 100-fold. A wide range of experiments demonstrated that in their compacted state, mammalian chromosomes form arrays of closely stacked consecutive ∼100 kb loops. The mechanism underlying the active process of chromosome compaction into a stack of loops is unknown. Here we test the hypothesis that chromosomes are compacted by enzymatic machines that actively extrude chromatin loops. When such loop-extruding factors (LEF) bind to chromosomes, they progressively bridge sites that are further away along the chromosome, thus extruding a loop. We demonstrate that collective action of LEFs leads to formation of a dynamic array of consecutive loops. Simulations and an analytically solved model identify two distinct steady states: a sparse state, where loops are highly dynamic but provide little compaction; and a dense state, where there are more stable loops and dramatic chromosome compaction. We find that human chromosomes operate at the border of the dense steady state. Our analysis also shows how the macroscopic characteristics of the loop array are determined by the microscopic properties of LEFs and their abundance. When the number of LEFs are used that match experimentally based estimates, the model can quantitatively reproduce the average loop length, the degree of compaction, and the general loop-array morphology of compact human chromosomes. Our study demonstrates that efficient chromosome compaction can be achieved solely by an active loop-extrusion process. PMID:27224481

  20. Compaction of asphalt pavement. Final report

    SciTech Connect

    Hughes, C.S.

    1989-10-01

    This synthesis will be of interest to construction and materials engineers, paving contractors, equipment manufacturers, and others who are involved in assessing the performance of asphalt pavements. Information is presented on various issues related to compaction of asphalt pavements. Compaction is one of the most important factors affecting the performance of asphalt pavements. The report of the Transportation Research Board describes the theory, methods, equipment, and specifications related to the compaction of asphalt pavements. A brief history of, the importance of, and factors affecting compaction are also discussed. Construction influences, density measurements, and trends are also considered.

  1. Gravitational waves from compact objects

    NASA Astrophysics Data System (ADS)

    de Freitas Pacheco, José Antonio

    2010-11-01

    Large ground-based laser beam interferometers are presently in operation both in the USA (LIGO) and in Europe (VIRGO) and potential sources that might be detected by these instruments are revisited. The present generation of detectors does not have a sensitivity high enough to probe a significant volume of the universe and, consequently, predicted event rates are very low. The planned advanced generation of interferometers will probably be able to detect, for the first time, a gravitational signal. Advanced LIGO and EGO instruments are expected to detect few (some): binary coalescences consisting of either two neutron stars, two black holes or a neutron star and a black hole. In space, the sensitivity of the planned LISA spacecraft constellation will allow the detection of the gravitational signals, even within a “pessimistic" range of possible signals, produced during the capture of compact objects by supermassive black holes, at a rate of a few tens per year.

  2. Compact Microwave Fourier Spectrum Analyzer

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

    2009-01-01

    A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

  3. Scalar curvature and projective compactness

    NASA Astrophysics Data System (ADS)

    ?ap, Andreas; Gover, A. Rod

    2015-12-01

    Consider a manifold with boundary, and such that the interior is equipped with a pseudo-Riemannian metric. We prove that, under mild asymptotic non-vanishing conditions on the scalar curvature, if the Levi-Civita connection of the interior does not extend to the boundary (because for example the interior is complete) whereas its projective structure does, then the metric is projectively compact of order 2; this order is a measure of volume growth towards infinity. This implies a host of results including that the metric satisfies asymptotic Einstein conditions, and induces a canonical conformal structure on the boundary. Underpinning this work is a new interpretation of scalar curvature in terms of projective geometry. This enables us to show that if the projective structure of a metric extends to the boundary then its scalar curvature also naturally and smoothly extends.

  4. Anisotropic models for compact stars

    NASA Astrophysics Data System (ADS)

    Maurya, S. K.; Gupta, Y. K.; Ray, Saibal; Dayanandan, Baiju

    2015-05-01

    In the present paper we obtain an anisotropic analog of the Durgapal and Fuloria (Gen Relativ Gravit 17:671, 1985) perfect fluid solution. The methodology consists of contraction of the anisotropic factor with the help of both metric potentials and . Here we consider the same as Durgapal and Fuloria (Gen Relativ Gravit 17:671, 1985) did, whereas is as given by Lake (Phys Rev D 67:104015, 2003). The field equations are solved by the change of dependent variable method. The solutions set mathematically thus obtained are compared with the physical properties of some of the compact stars, strange star as well as white dwarf. It is observed that all the expected physical features are available related to the stellar fluid distribution, which clearly indicates the validity of the model.

  5. Compact anti-radon facility

    NASA Astrophysics Data System (ADS)

    Fajt, L.; Kouba, P.; Mamedov, F.; Smolek, K.; Štekl, I.; Fojtík, P.; Hýža, M.; Hůlka, J.; Jílek, K.; Stoček, P.; Veselý, J.; Busto, J.

    2015-08-01

    Suppression of radon background is one of main tasks in ultra-low background experiments. The most promising technique for suppression of radon is its adsorption on charcoal. Within the frame of the NEMO-3 experiment, radon trapping facility (RTF) was installed in Modane underground laboratory in 2004. Based on long-term experience with this facility a new compact transportable anti-radon facility was constructed in cooperation among IEAP CTU, SÚRO and ATEKO company. The device provides 20m3/h of purified air (air radon activity at the output ˜10mBq/m3). The basic features and preliminary results of anti-radon device testing are presented.

  6. Compact laser Doppler choroidal flowmeter

    NASA Astrophysics Data System (ADS)

    Geiser, Martial H.; Diermann, Ulrich; Riva, Charles E.

    1999-10-01

    A compact instrument is described that allows the measurement of the laser Doppler flow parameters, i.e., the velocity, the volume, and flow of blood in the foveal region of the human choroidal vascular system. This new device uses the optical principle of confocality for the delivery of the laser light to the site of measurement and heterodyne detection of the Doppler frequency shifted scattered light. Power of the incident light (785 nm) at the cornea is 90 (mu) W. Measurements were obtained in both eyes of a group of 21 normal volunteers without pupil dilatation. We determined the intrasubject reproducibility and the minimum statistically significant detectable changes in the flow parameters for a group of 21 eyes (one in each subject). Linear correlations were also established between the flow parameters in the right and left eyes.

  7. Magnetohydrodynamics stability of compact stellarators

    NASA Astrophysics Data System (ADS)

    Fu, G. Y.; Ku, L. P.; Cooper, W. A.; Hirshman, S. H.; Monticello, D. A.; Redi, M. H.; Reiman, A.; Sanchez, R.; Spong, D. A.

    2000-05-01

    Recent stability results of external kink modes and vertical modes in compact stellarators are presented. The vertical mode is found to be stabilized by externally generated poloidal flux. A simple stability criterion is derived in the limit of large aspect ratio and constant current density. For a wall at infinite distance from the plasma, the amount of external flux needed for stabilization is given by Fi=(κ2-κ)/(κ2+1), where κ is the axisymmetric elongation and Fi is the fraction of the external rotational transform. A systematic parameter study shows that the external kink mode in a quasiaxisymmetric stellarator (QAS) can be stabilized at high beta (˜5%) without a conducting wall by magnetic shear via three-dimensional (3D) shaping. It is found that external kinks are driven by both parallel current and pressure gradient. The pressure contributes significantly to the overall drive through the curvature term and the Pfirsch-Schluter current.

  8. 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.

  9. 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.

  10. Ductile compaction in volcanic conduits

    NASA Astrophysics Data System (ADS)

    Wadsworth, Fabian; Vasseur, Jeremie; Lavalle, Yan; Scheu, Bettina; Dingwell, Donald

    2014-05-01

    Silicic magmas typically outgas through connected pore and crack networks with a high gas permeability without the need for decoupled movement of pores in the melt. It is the efficiency with which this process can occur which governs the pressure in the pore network. However, such a connected coupled network is generally mechanically unstable and will relax until volume equilibrium when the pores become smaller and isolated. Consequently, gas permeability can be reduced during densification. Cycles of outgassing events recorded in gas monitoring data show that permeable flow of volatiles is often transient, which is interpreted to reflect magma densification and the closing of pore-networks. Understanding the timescale over which this densification process occurs is critical to refining conduit models that seek to predict the pressure evolution in a pore-network leading to eruptions. We conduct uniaxial compaction experiments to parameterize non-linear creep and relaxation processes that occur in magmas with total pore fractions 0.2-0.85. We analyze our results by applying both viscous sintering and viscoelastic deformation theory to test the applicability of currently accepted models to flow dynamics in the uppermost conduit involving highly porous magmas. We show that purely ductile compaction can occur rapidly and that pore networks can close over timescales analogous to the inter-eruptive periods observed during classic cyclic eruptions such as those at Soufriere Hills volcano, Montserrat, in 1997. At upper-conduit axial stresses (0.1-5 MPa) and magmatic temperatures (830-900 oC), we show that magmas can evolve to porosities analogous to dome lavas erupted at the same volcano. Such dramatic densification events over relatively short timescales and in the absence of brittle deformation show that permeable flow will be inhibited at upper conduit levels. We therefore propose that outgassing is a key feature at many silicic volcanoes and should be incorporated into conduit flow models.

  11. Sandstone compaction: Basis for porosity predictive capabilities

    SciTech Connect

    Houseknecht, D.W.; Dincau, A.R.; Freeman, C.W. )

    1991-03-01

    Prediction of sandstone porosity must be based on understanding physical and chemical processes that are genetically linked to geologic history. Petrographic studies of sandstones of diverse geologic history indicate that reduction of intergranular volume (IGV) by compaction is the primary control of porosity in most cases. Moreover, these studies demonstrate that compaction can commonly be related to geologic history. Maximum depth of burial exerts a primary control on compaction in nondeformed and mildly deformed basins. For example, Miocene sandstones of Louisiana and Tertiary and Cretaceous sandstones of the Green River basin display progressive compaction to the depth limit of conventional core control. Compaction has reduced average IGV to less than 20% at 7.5 km (25,000 ft) depth in Miocene sandstones of Louisiana and to less than 10% at 5.3 km (17,500 ft) depth in Cretaceous sandstones in the Green River basin. Differences in absolute values of IGV in these basins reflect other geologic variables that have influenced compaction, including thermal maturity and age. In both basins, a progressive gradation from predominantly mechanical compaction-shallow to predominantly chemical compaction-deep is observed. Previous work in older basins indicates that chemical compaction remains an important agent of porosity modification in sandstones that undergo additional physical, chemical, and thermal stress. Compaction progressively reduces the intergranular volume of sandstones, thereby directly controlling intergranular porosity and influencing chemical diagenesis by modifying plumbing systems. Thus quantification of compaction in sandstones of diverse geologic history is fundamental to the development of porosity predictive capabilities.

  12. Charged Q-balls and boson stars and dynamics of charged test particles

    NASA Astrophysics Data System (ADS)

    Brihaye, Yves; Diemer, Valeria; Hartmann, Betti

    2014-04-01

    We construct electrically charged Q-balls and boson stars in a model with a scalar self-interaction potential resulting from gauge mediated supersymmetry breaking. We discuss the properties of these solutions in detail and emphasize the differences to the uncharged case. We observe that Q-balls can only be constructed up to a maximal value of the charge of the scalar field, while for boson stars the interplay between the attractive gravitational force and the repulsive electromagnetic force determines their behavior. We find that the vacuum is stable with respect to pair production in the presence of our charged boson stars. We also study the motion of charged, massive test particles in the space-time of boson stars. We find that in contrast to charged black holes the motion of charged test particles in charged boson star space-times is planar, but that the presence of the scalar field plays a crucial role for the qualitative features of the trajectories. Applications of this test particle motion can be made in the study of extreme-mass ratio inspirals as well as astrophysical plasmas relevant e.g. in the formation of accretion discs and polar jets of compact objects.

  13. 77 FR 20051 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-03

    ... notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr. Gary S. Barron at (304) 625-2803... CONTACT: Inquiries may be addressed to Mr. Gary S. Barron, FBI Compact Officer, Module D3, 1000 Custer...: March 27, 2012. Gary S. Barron, FBI Compact Officer, Criminal Justice Information Services...

  14. Compaction within the South Belridge diatomite

    SciTech Connect

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

    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).

  15. 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.

  16. Physics of compact ignition tokamak designs

    SciTech Connect

    Singer, C.E.; Ku, L.P.; Bateman, G.; Seidl, F.; Sugihara, M.

    1986-03-01

    Models for predicting plasma performance in compact ignition experiments are constructed on the basis of theoretical and empirical constraints and data from tokamak experiments. Emphasis is placed on finding transport and confinement models which reproduce results of both ohmically and auxiliary heated tokamak data. Illustrations of the application of the models to compact ignition designs are given.

  17. Lithographic Replication Of Compact Disk Structures

    NASA Astrophysics Data System (ADS)

    Revay, Robert E.; Briaud, Philippe

    1989-07-01

    Conventional UV photolithography has been applied to the replication of glass compact disk structures for low cost fabrication of grooved glass substrates and ruggedized CD-ROM and CD-AUDIO disks. Unconventional pattern generation and replication strategies have been employed to produce high quality compact disk structures in soda-lime glass substrates.

  18. The Compact Route from Boston to London.

    ERIC Educational Resources Information Center

    Wright, Brian

    1988-01-01

    The author describes the development and implementation of a business/secondary school compact in East London, based on the original Boston Compact. This cooperative relationship helps disadvantaged students attain employability skills and work experience, while employers gain a trained labor force for their entry-level jobs. (CH)

  19. Shock compaction of molybdenum nitride powder

    NASA Astrophysics Data System (ADS)

    Roberson, S.; Davis, R. F.; Joshi, V. S.; Fienello, D.

    1998-07-01

    Molybdenum nitride has a potential application in multi layer capacitors. Since this material is not readily available in bulk form, molybdenum nitride powder, consisting of a mixture of the nitrides Mo2N and MoN has been compacted to 12 mm circular, 1-2 mm thick discs utilizing shock-compression technique. Powders were packed to 55-67 percent of the crystal density and shock compacted using a plate impact shock recovery system at 1.35 to 1.81 km/s impact velocity. The recovered compacts were characterized by scanning electron microscope, x-ray diffraction and cyclic voltammetry to evaluate its electrochemical stability in sulphuric acid. This paper presents the optimization technique used for compaction and the characteristics of the recovered compacts.

  20. 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.

  1. MHD Stability in Compact Stellarators

    NASA Astrophysics Data System (ADS)

    Fu, Guoyong

    1999-11-01

    A key issue for current carrying compact stellarators(S.P. Hirshman et al., "Physics of compact stellarators", Phys. Plasmas 6, 1858 (1999).) is the stability of ideal MHD modes. We present recent stability results of external kink modes, ballooning mode, and vertical modes in Quasi-axisymmetric Stellarators (QAS)( A. Reiman et al, "Physics issue in the design of a high beta Quasi-Axisymmetric Stellarator" the 17th IAEA Fusion Energy conference, (Yokohama, Japan, October 1998), Paper ICP/06.) as well as Quasi-Omnigeneous Stellarators (QOS)^2. The 3D stability code Terpsichore(W. A. Cooper et al., Phys. Plasmas 3, 275 (1996)) is used in this study. The vertical stability in a current carrying stellarator is studied for the first time. The vertical mode is found to be stabilized by externally generated poloidal flux(G.Y. Fu et al., "Stability of vertical mode in a current carrying stellarator"., to be submitted). Physically, this is because the external poloidal flux enhances the field line bending energy relative to the current drive term in the MHD energy principle, δ W. A simple stability criteria is derived in the limit of large aspect ratio and constant current density. For wall at infinite distance from the plasma, the amount of external flux needed for stabilization is given by f=(κ^2-κ)/(κ^2+1) where κ is the axisymmetric elongation and f is the fraction of the external rotational transform at the plasma edge. A systematic parameter study shows that the external kink in QAS can be stabilized at high beta ( ~ 5%) without a conducting wall by combination of edge magnetic shear and 3D shaping(G. Y. Fu et al., "MHD stability calculations of high-beta Quasi-Axisymmetric Stellarators", the 17th IAEA Fusion Energy conference, (Yokohama, Japan, October 1998), paper THP1/07.). The optimal shaping is obtained by using an optimizer with kink stability included in its objective function. The physics mechanism for the kink modes is studied by examining relative contributions of individual terms in δ W. It is found the external kinks are mainly driven by the parallel current. The pressure contributes significantly to the overall drive through the curvature term and the Pfirsch-Schluter current. These results demonstrate potential of QAS and QOS for disruption-free operations at high-beta without a close-fitting conducting wall and feedback stabilization.

  2. Compact dynamic microfluidic iris array

    NASA Astrophysics Data System (ADS)

    Kimmle, Christina; Doering, Christoph; Steuer, Anna; Fouckhardt, Henning

    2011-09-01

    A dynamic microfluidic iris is realized. Light attenuation is achieved by absorption of an opaque liquid (e.g. black ink). The adjustment of the iris diameter is achieved by fluid displacement via a transparent elastomer (silicone) half-sphere. This silicone calotte is hydraulically pressed against a polymethylmethacrylate (PMMA) substrate as the bottom window, such that the opaque liquid is squeezed away, this way opening the iris. With this approach a dynamic range of more than 60 dB can be achieved with response times in the ms to s regime. The design allows the realization of a single iris as well as an iris array. So far the master for the molded silicone structure was fabricated by precision mechanics. The aperture diameter was changed continuously from 0 to 8 mm for a single iris and 0 to 4 mm in case of a 3 x 3 iris array. Moreover, an iris array was combined with a PMMA lens array into a compact module, the distance of both arrays equaling the focal length of the lenses. This way e.g. spatial frequency filter arrays can be realized. The possibility to extend the iris array concept to an array with many elements is demonstrated. Such arrays could be applied e.g. in light-field cameras.

  3. Compact optical RF spectrum analyzer

    NASA Astrophysics Data System (ADS)

    Lee, John N.; Verber, Carl M.

    1991-06-01

    An improved compact optical and rugged laser-driven RF spectrum analyzer being made up of slab-like waveguide means is discussed. The waveguide means has at one end enhanced surface diffraction grating means for intercepting and selectively diffracting a laser source beam so that the diffracted laser beam is deflected, expanded and focussed to converge toward the other end and in relation to both a surface acoustic wave (SAW) and detector array means. The waveguide means includes novel combined signal detection and arcuate-shaped transducer (CSD/AT) means between its ends for forming and directing the SAW in response to a detected RF (microwave) signal to be analyzed such that the SAW optically intercepts, interacts and further diffracts in Bragg-Cell-like fashion that converging beam so as to deflect same relative to detector array means at the other end of the waveguide means. The detector array means normally analyzes a series of differently deflected beams so as to provide frequency distribution and intensity of one or more detected signals.

  4. The National Compact Stellarator Experiment

    NASA Astrophysics Data System (ADS)

    Neilson, G. H.; Goldston, R. J.; Monticello, D. A.; Reiersen, W. T.; Reiman, A. H.; Zarnstorff, M. C.; Hirshman, S. P.; Lyon, J. F.

    1998-11-01

    The NCSX will be a new experimental facility to test promising compact stellarator plasma configurations which use both coil and bootstrap currents to generate the rotational transform. The goals are to demonstrate disruption-free operation at high β and study β limits, stability, transport, plasma control, and power and particle handling. The NCSX will be constructed by modifying the PBX-M facility, re-using its existing tokamak magnet set, vacuum vessel, neutral beams, diagnostics, and ancillary systems. New coils will be installed inside the vacuum vessel to provide 3D stellarator shaping fields and control the rotational transform profile. The initial design uses a quasi-axisymmetric stellarator plasma configuration optimized for low transport and for stability at high β. Initial machine parameters are B_0=1 T, R≈1.5 m, a≈0.4 m, P_NB=6 MW and t_pulse=0.3 s. Upgrade possibilities are to add 6 MW of ICRF heating power, increase t_pulse to 3 s, increase B0 to 2 T, and reconfigure the coils to test different plasma configurations. First plasma is planned for 2002.

  5. Compact coherent optical correlator system

    NASA Astrophysics Data System (ADS)

    Upatnieks, Juris; Abshier, James O.

    1988-05-01

    A real-time coherent optical correlator was designed, fabricated and tested. The correlator features 30 separate filters, low-light level real-time operation, and a compact design. The correlator is packaged in a cylinder 15 cm in diameter by 30 cm long, excluding imaging lens. Each of the two laser diode coherent light sources is imaged to 15 locations with holographic optical elements (HOEs). The HOEs perform a number of functions usually requiring several optical components. The HOEs correct the aspect ratio of the laser diode beams, perform the functions of collimating and Fourier transform lenses, multiplex the light beam to form multiple Fourier transforms, and correct a variety of system aberrations. Low-light operation is achieved with a microchannel image intensifier in front of a liquid crystal light modulator. This arrangement allows the correlator to operate over a wide range of light levels, from full sunlight to dusk. The image intensifier, however, reduces system resolution and response time. A computer controlled filter maker system was designed to automate filter recording. The computer, a small PC-type, controls the position of the recording plate, the reference beam angle, dwell and exposure times, and checks light source and shutter operation.

  6. Dynamic compaction of granular materials

    PubMed Central

    Favrie, N.; Gavrilyuk, S.

    2013-01-01

    An Eulerian hyperbolic multiphase flow model for dynamic and irreversible compaction of granular materials is constructed. The reversible model is first constructed on the basis of the classical Hertz theory. The irreversible model is then derived in accordance with the following two basic principles. First, the entropy inequality is satisfied by the model. Second, the corresponding ‘intergranular stress’ coming from elastic energy owing to contact between grains decreases in time (the granular media behave as Maxwell-type materials). The irreversible model admits an equilibrium state corresponding to von Mises-type yield limit. The yield limit depends on the volume fraction of the solid. The sound velocity at the yield surface is smaller than that in the reversible model. The last one is smaller than the sound velocity in the irreversible model. Such an embedded model structure assures a thermodynamically correct formulation of the model of granular materials. The model is validated on quasi-static experiments on loading–unloading cycles. The experimentally observed hysteresis phenomena were numerically confirmed with a good accuracy by the proposed model. PMID:24353466

  7. 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

  8. 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

  9. Compact, harmonic multiplying gyrotron amplifiers

    SciTech Connect

    Guo, H.Z.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Tate, J.; Chen, S.H.

    1995-12-31

    A compact, harmonic multiplying gyrotron traveling wave amplifier is being developed. The device is a three-stage tube with the output section running as a fourth harmonic gyro-TWT, the input section running as a fundamental gyro-TWT, and the middle operating at the second harmonic of the cyclotron frequency. Radiation is suppressed by servers between the sections. The operating beam of the tube is produced by a magnetron injection gun (MIG). A TE{sub 0n} mode selective interaction circuit consisting of mode converters and a filter waveguide is employed for both input and output sections to solve the mode competition problem, which is pervasive in gyro-TWT operation. The input section has an input coupler designed as a TE{sub 0n} mode launcher. It excites a signal at the fundamental cyclotron frequency (17.5 GHz), which is amplified in the first TWT interaction region. So far the device is similar to a two-stage harmonic gyro-TWT. The distinction is that in the three-stage device the second section will be optimized not for output power but for fourth harmonic bunching of the beam. A gyroklystron amplifier has also been designed. The configuration is similar to the gyro-TWT but with the traveling wave interaction structures replaced by mode selective special complex cavities. Cold test results of the wideband input coupler and the TE{sub 0n} mode selective interaction circuit have been obtained.

  10. Field performance of compacted clay liners

    SciTech Connect

    Benson, C.H.; Daniel, D.E.; Boutwell, G.P.

    1999-05-01

    A database consisting of 85 full-scale compacted clay liners was assembled to evaluate field hydraulic conductivity K{sub F}. Large-scale field hydraulic conductivity tests were conducted on each liner. All of the clay liners were intended to achieve K{sub F} {le} 1 {times} 10{sup {minus}7} cm/s, but only 74% succeeded in meeting this objective. The important factors affecting K{sub F} are the soil wetness relative to the line of optimums and the number of lifts or the thickness of the liner. Poor correlation exists between K{sub F} and hydraulic conductivities measured in the laboratory (K{sub L}) on field-compacted samples (especially for liners with K{sub F} > 10{sup {minus}7} cm/s compacted at lower water contents relative to the line of optimums), percent compaction, and index properties representative of composition (e.g., Atterberg limits and particle size fractions). The findings indicate that (1) compacted clay liners having K{sub F} {le} 10{sup {minus}7} cm/s can be constructed with a broad variety of clayey soils; (2) the primary emphasis should be ensuring compaction is primarily wet of the line of optimums; (3) less emphasis should be placed on other traditional measures such as percent compaction, K{sub L}, and index properties; and (4) liners that are thicker or have a greater number of lifts tend to have lower K{sub F}.

  11. 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.

  12. Charge exchange system

    DOEpatents

    Anderson, Oscar A.

    1978-01-01

    An improved charge exchange system for substantially reducing pumping requirements of excess gas in a controlled thermonuclear reactor high energy neutral beam injector. The charge exchange system utilizes a jet-type blanket which acts simultaneously as the charge exchange medium and as a shield for reflecting excess gas.

  13. Spacecraft Charging Technology, 1980

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The third Spacecraft Charging Technology Conference proceedings contain 66 papers on the geosynchronous plasma environment, spacecraft modeling, charged particle environment interactions with spacecraft, spacecraft materials characterization, and satellite design and testing. The proceedings is a compilation of the state of the art of spacecraft charging and environmental interaction phenomena.

  14. 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

  15. 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)

  16. Low-Temperature TiOx Compact Layer for Planar Heterojunction Perovskite Solar Cells.

    PubMed

    Liu, Zonghao; Chen, Qi; Hong, Ziruo; Zhou, Huanping; Xu, Xiaobao; De Marco, Nicholas; Sun, Pengyu; Zhao, Zhixin; Cheng, Yi-Bing; Yang, Yang

    2016-05-01

    Here, we demonstrate an effective low-temperature approach to fabricate a uniform and pinhole-free compact TiO2 layer for enhancing photovoltaic performance of perovskite solar cells. TiCl4 was used to modify TiO2 for efficient charge generation and significantly reduced recombination loss. We found that a TiO2 layer with an appropriate TiCl4 treatment possesses a smooth surface with full coverage of the conductive electrode. Further studies on charge carrier dynamics confirmed that the TiCl4 treatment improves the contact of the TiO2/perovskite interface, facilitating charge extraction and suppressing charge recombination. On the basis of the treatment, we improved the open circuit voltage from 1.01 V of the reference cell to 1.08 V, and achieved a power conversion efficiency of 16.4%. PMID:27058279

  17. 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.

  18. Compacting Plastic-Bonded Explosive Molding Powders to Dense Solids

    SciTech Connect

    B. Olinger

    2005-04-15

    Dense solid high explosives are made by compacting plastic-bonded explosive molding powders with high pressures and temperatures for extended periods of time. The density is influenced by manufacturing processes of the powders, compaction temperature, the magnitude of compaction pressure, pressure duration, and number of repeated applications of pressure. The internal density variation of compacted explosives depends on method of compaction and the material being compacted.

  19. 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.

  20. Compact vs. Exponential-Size LP Relaxations

    SciTech Connect

    Carr, R.D.; Lancia, G.

    2000-09-01

    In this paper we introduce by means of examples a new technique for formulating compact (i.e. polynomial-size) LP relaxations in place of exponential-size models requiring separation algorithms. In the same vein as a celebrated theorem by Groetschel, Lovasz and Schrijver, we state the equivalence of compact separation and compact optimization. Among the examples used to illustrate our technique, we introduce a new formulation for the Traveling Salesman Problem, whose relaxation we show equivalent to the subtour elimination relaxation.

  1. Strategy Guideline. Compact Air Distribution Systems

    SciTech Connect

    Burdick, Arlan

    2013-06-01

    This guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.

  2. 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.

  3. Optimization of Compact Microwave Ion Source for Generation of High Current and Low Energy Ion Beam

    SciTech Connect

    Taguchi, Shuhei; Gotoh, Yasuhito; Tsuji, Hiroshi; Sakai, Shigeki; Ishikawa, Junzo

    2011-01-07

    The purpose of the present study is to obtain a 0.5 keV Ar{sup +} beam with a current of hundreds {mu}A for space charge neutralization experiment. 0.5 keV Ar{sup +} beam with a current of 127 {mu}A was obtained by optimization of compact microwave ion source, and the divergence of the generated ion beam due to its space charge was investigated. As a result, the ratio of transported ion current for 700 mm within the diameter of 160 mm to the generated ion current was 0.41.

  4. Fractal Model of a Compact Intracloud Discharge. I. Features of the Structure and Evolution

    NASA Astrophysics Data System (ADS)

    Iudin, D. I.; Davydenko, S. S.

    2015-12-01

    We propose a new model of a compact intracloud discharge considered as the result of interaction between two (or more) bipolar streamer structures formed in a strong large-scale electric field of a thundercloud. The model assumes two stages of the compact discharge development. At the preliminary stage, two or more bipolar streamer structures appear successively in the thundercloud in the region of a strong electric field (at the boundaries between the regions of the main positive and the main negative electric charges or between the main positive charge region and the top negative screening layer). The time of development of such structures is determined by the characteristics of the conducting channels that form them and can reach tens of milliseconds. Spatiotemporal synchronization of the bipolar streamer structures is provided by the altitude modulation of the electric field, which, in particular, can originate from a large-scale turbulence of the cloud medium or the stream instability. It is shown that a single bipolar streamer structure accumulates significant electric charges of different signs at its ends as it develops. The start of the main stage of a compact intracloud discharge corresponds to the occurrence of the conducting channel (breakdown of the gap) between the mature streamer structures. The electric charge accumulated at the adjacent ends of the structures at this stage is neutralized over a time much shorter than the duration of the preliminary stage. The parameters of the current pulse are in good agreement with the estimates of the current of a compact intracloud discharge which were obtained in the transmission-line approximation.

  5. Application of compact electron cyclotron resonance ion source

    SciTech Connect

    Muramatsu, M.; Kitagawa, A.; Iwata, Y.; Ogawa, H.; Hojo, S.; Kubo, T.; Kato, Y.; Biri, S.; Fekete, E.; Yoshida, Y.; Drentje, A. G.

    2008-02-15

    The compact electron cyclotron resonance (ECR) ion source with a permanent magnet configuration (Kei2 source) has been developed at National Institute of Radiological Sciences for a new carbon therapy facility. The Kei2 source was designed for production of C{sup 4+} ions; its performance such as beam intensity and stability has already reached the medical requirements. Therefore, the prototype development of the source for medical use is essentially finished. Recently, we have started a few studies on other applications of the source. One is the production of fullerenes in the ECR plasma and modified fullerenes with various atoms for new materials. A second application is the production of multiply charged ions (not only carbon) for ion implantation. In this paper, some basic experiments for these applications are reported.

  6. Compact laser radar and three-dimensional camera.

    PubMed

    Medina, Antonio; Gayá, Francisco; del Pozo, Francisco

    2006-04-01

    A novel three-dimensional (3D) camera is capable of providing high-precision 3D images in real time. The camera uses a diode laser to illuminate the scene, a shuttered solid-state charge-coupled device (CCD) sensor, and a simple phase detection technique based on the sensor shutter. The amplitude of the reflected signal carries the luminance information, while the phase of the signal carries range information. The system output is coded as a video signal. This camera offers significant advantages over existing technology. The precision in range is dependent only on phase shift and laser power and theoretically is far superior to existing time-of-flight laser radar systems. Other advantages are reduced size and simplicity and compact and inexpensive construction. We built a prototype that produced high-resolution images in range the (z) and x-y. PMID:16604759

  7. 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.

    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.

  8. Our compact with tomorrow's doctors.

    PubMed

    Cohen, Jordan J

    2002-06-01

    In recent years, the image of medicine as a caring profession has been badly tarnished by a rash of critical reports in the media. In the face of this negative publicity, do young people still want to be doctors? The author reviews conventional reasons given for the declining applicant pool (e.g., issues of declining income, loss of autonomy, etc.) and posits that an additional reason may be perceptions that doctors no longer command respect and that they are being oppressed by, rather than being guardians of, the health care system. Such views challenge academic medicine to broadcast to the world a realistic picture of the fabulous opportunities and gratifications that lie ahead for the next generation of physicians. However, academic medicine must also address some current realities within medical education, such as the admission process (where at present there is a tendency to overemphasize indices of academic achievement and underemphasize the personal characteristics sought in applicants) and the acculturation process in medical school (which can often dehumanize students and convert idealistic ones into cynics). The author acknowledges that these are tough challenges. He suggests as a first step that leaders of academic medicine prepare and disseminate an explicit statement of their commitments, a kind of compact between teachers and learners of medicine. He outlines these commitments, and states his hope that by fulfilling them, the academic medicine community can make clear that medicine-which at its core is still about the doctor-patient relationship-is a true calling, not just beleaguered occupation. PMID:12063190

  9. Collisional Charging in Ice

    NASA Astrophysics Data System (ADS)

    Wettlaufer, John S.; Dash, J. Gregory; Mason, Brian L.

    2000-03-01

    We discuss a theory of the microscopic process of collisional charging of ice that describes the systematic dependence of charge and mass transfer on growth rate, temperature and impact energy. The theory involves mechanisms which become successively involved and interdependent in the collision process. Predicted trends and values of charge and mass transfer agree with measurements: during collisions at temperatures down to -20 degrees Celcius or lower the particle growing more rapidly charges positively, and the magnitude of charge transfer increases with growth rate.

  10. Compact pulsed electron beam system for microwave generation

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.; Deb, P.; Shukla, R.; Banerjee, P.; Prabaharan, T.; Adhikary, B.; Verma, R.; Sharma, A.; Shyam, A.

    2012-11-01

    A compact 180 kV electron beam system is designed for high power microwave generation. The electron beam system is consists of a secondary energy storage device, which can deliver energy to the load at faster rate than usual primary energy storage system such as tesla transformers or marx generator. The short duration, high voltage pulse with fast rise time and good flattop is applied to vacuum diode for high power microwave generation. The compact electron beam system is made up of single turn primary tesla transformer which charges a helical pulse forming line and transfers its energy to vacuum diode through a high voltage pressurized spark gap switch. We have used helical pulse forming line which has higher inductance as compared to coaxial pulse forming line, which in turns increases, the pulse width and reduce the length of the pulse forming line. Water dielectric medium is used because of its high dielectric constant, high dielectric strength and efficient energy storage capability. The time dependent breakdown property and high relative permittivity of water makes it an ideal choice for this system. The high voltage flat-top pulse of 90 kV, 260 ns is measured across the matched load. In this article we have reported the design details, simulation and initial experimental results of 180 kV pulsed electron beam system for high power microwave generation.

  11. Proppant charge and method

    SciTech Connect

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

    1986-01-14

    This patent describes a pre-cured proppant charge for propping a fracture in a subterranean well, the charge being pre-cured prior to injection into the subterranean well. The pre-cured proppant charge consists of resin coated sand particles most of which are composed of a single substrate particle with a thermoset resite coating. The resite coating placed on such sand particles of a proppant charge, produces a charge wherein at least one of: (a) the Conductivity Ratio throughout a given closure stress range is greater than the charge of the uncoated sand particles having substantially the same particle size distribution; or (b) the Permeability Ratio throughout the stress range of 2,000-10,000 p.s.i. is at least about 30% that of a sintered bauxite charge of substantially the same particle size, the resin for the coating being at least one of: (1) a resole; or (2) a novolac.

  12. A compact bipolar pulse-forming network-Marx generator based on pulse transformers

    NASA Astrophysics Data System (ADS)

    Zhang, Huibo; Yang, Jianhua; Lin, Jiajin; Yang, Xiao

    2013-11-01

    A compact bipolar pulse-forming network (PFN)-Marx generator based on pulse transformers is presented in this paper. The high-voltage generator consisted of two sets of pulse transformers, 6 stages of PFNs with ceramic capacitors, a switch unit, and a matched load. The design is characterized by the bipolar pulse charging scheme and the compact structure of the PFN-Marx. The scheme of bipolar charging by pulse transformers increased the withstand voltage of the ceramic capacitors in the PFNs and decreased the number of the gas gap switches. The compact structure of the PFN-Marx was aimed at reducing the parasitic inductance in the generator. When the charging voltage on the PFNs was 35 kV, the matched resistive load of 48 Ω could deliver a high-voltage pulse with an amplitude of 100 kV. The full width at half maximum of the load pulse was 173 ns, and its rise time was less than 15 ns.

  13. A compact bipolar pulse-forming network-Marx generator based on pulse transformers.

    PubMed

    Zhang, Huibo; Yang, Jianhua; Lin, Jiajin; Yang, Xiao

    2013-11-01

    A compact bipolar pulse-forming network (PFN)-Marx generator based on pulse transformers is presented in this paper. The high-voltage generator consisted of two sets of pulse transformers, 6 stages of PFNs with ceramic capacitors, a switch unit, and a matched load. The design is characterized by the bipolar pulse charging scheme and the compact structure of the PFN-Marx. The scheme of bipolar charging by pulse transformers increased the withstand voltage of the ceramic capacitors in the PFNs and decreased the number of the gas gap switches. The compact structure of the PFN-Marx was aimed at reducing the parasitic inductance in the generator. When the charging voltage on the PFNs was 35 kV, the matched resistive load of 48 ? could deliver a high-voltage pulse with an amplitude of 100 kV. The full width at half maximum of the load pulse was 173 ns, and its rise time was less than 15 ns. PMID:24289423

  14. ACTIVELY CONTROLLED AFTERBURNER FOR COMPACT WASTE INCINERATION

    EPA Science Inventory

    In a continuing research program directed at developing technology for compact shipboard incinerators, active control of fluid dynamics has been used to enhance mixing in incinerator afterburner (AB) experiments and increase the DRE for a waste surrogate. Experiments were conduc...

  15. Deep Compaction Control of Sandy Soils

    NASA Astrophysics Data System (ADS)

    Bałachowski, Lech; Kurek, Norbert

    2015-02-01

    Vibroflotation, vibratory compaction, micro-blasting or heavy tamping are typical improvement methods for the cohesionless deposits of high thickness. The complex mechanism of deep soil compaction is related to void ratio decrease with grain rearrangements, lateral stress increase, prestressing effect of certain number of load cycles, water pressure dissipation, aging and other effects. Calibration chamber based interpretation of CPTU/DMT can be used to take into account vertical and horizontal stress and void ratio effects. Some examples of interpretation of soundings in pre-treated and compacted sands are given. Some acceptance criteria for compaction control are discussed. The improvement factors are analysed including the normalised approach based on the soil behaviour type index.

  16. Steady state compact toroidal plasma production

    DOEpatents

    Turner, William C.

    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.

  17. Compact ignition tokamak size/cost study

    SciTech Connect

    Flanagan, C.A.; Hamilton, W.R.

    1985-01-01

    This report is comprised of viewgraphs. The objective of the talk is to examine the sensitivity of a compact ignition tokamak device with respect to device size (major radius) assuming siting at PPPL. (WRF)

  18. Diagnostics for the National Compact Stellarator Experiment

    SciTech Connect

    B.C. Stratton; D. Johnson; R. Feder; E. Fredrickson; H. Neilson; H. Takahashi; M. Zarnstorf; M. Cole; P. Goranson; E. Lazarus; B. Nelson

    2003-09-16

    The status of planning of the National Compact Stellarator Experiment (NCSX) diagnostics is presented, with the emphasis on resolution of diagnostics access issues and on diagnostics required for the early phases of operation.

  19. Compaction of DNA using C12EO4 cooperated with Fe(3.).

    PubMed

    Wang, Ling; Xu, Lu; Li, Guihua; Feng, Lei; Dong, Shuli; Hao, Jingcheng

    2016-08-01

    Nonionic surfactant, tetraethylene glycol monododecyl ether (C12EO4), cannot compact DNA because of its low efficiency in neutralizing the negative charges of the phosphate groups of DNA. It is also well-known that nonionic surfactants as a decompaction agent can help DNA be released from cationic surfactant aggregates. Herein, with the "bridge" Fe(3+) of C12EO4, we found that C12EO4 can efficiently compact DNA molecules into globular states with a narrow size distribution, indicating that the cooperative Fe(3+) can transform C12EO4 molecules from decompaction agents to compaction ones. The mechanism of the interaction of DNA and C12EO4 by "bridge" Fe(3+) is that the Fe(3+)-C12EO4 complexes act as multivalent ions by cooperative and hydrophobic interaction. The improved colloidal-stability and endosome escape effect induced by C12EO4 would provide the potential applications of nonionic surfactant in the physiological characteristics of DNA complexes. Cell viability assay demonstrates that Fe(3+)-C12EO4 complexes possess low cytotoxicity, ensuring good biocompatibility. Another advantage of this system is that the DNA complexes can be de-compacted by glutathione in cell without any other agents. This suggests the metal ion-nonionic surfactant complexes as compaction agent can act as the potential delivery tool of DNA in future nonviral gene delivery systems. PMID:27110911

  20. Design and Build a Compact Raman Sensor for Identification of Chemical Composition

    NASA Technical Reports Server (NTRS)

    Garcia, Christopher S.; Abedin, M. Nurul; Ismail, Syed; Sharma, Shiv K.; Misra, Anupam K.; Sandford, Stephen P.; Elsayed-Ali, Hani

    2008-01-01

    A compact remote Raman sensor system was developed at NASA Langley Research Center. This sensor is an improvement over the previously reported system, which consisted of a 532 nm pulsed laser, a 4-inch telescope, a spectrograph, and an intensified charge-coupled devices (CCD) camera. One of the attractive features of the previous system was its portability, thereby making it suitable for applications such as planetary surface explorations, homeland security and defense applications where a compact portable instrument is important. The new system was made more compact by replacing bulky components with smaller and lighter components. The new compact system uses a smaller spectrograph measuring 9 x 4 x 4 in. and a smaller intensified CCD camera measuring 5 in. long and 2 in. in diameter. The previous system was used to obtain the Raman spectra of several materials that are important to defense and security applications. Furthermore, the new compact Raman sensor system is used to obtain the Raman spectra of a diverse set of materials to demonstrate the sensor system's potential use in the identification of unknown materials.

  1. Rotating compact star with superconducting quark matter

    SciTech Connect

    Panda, P.K.; Nataraj, H.S.

    2006-02-15

    A compact star with a superconducting quark core, a hadron crust, and a mixed phase between the two is considered. The quark-meson coupling model for hadron matter and the color-flavor-locked quark model for quark matter is used to construct the equation of state for the compact star. The effect of pairing of quarks in the color-flavor-locked phase and the mixed phase on the mass, radius, and period of the rotating star is studied.

  2. 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.

  3. 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.

  4. 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.

  5. Dynamic compaction of tungsten carbide powder.

    SciTech Connect

    Gluth, Jeffrey Weston; Hall, Clint Allen; Vogler, Tracy John; Grady, Dennis Edward

    2005-04-01

    The shock compaction behavior of a tungsten carbide powder was investigated using a new experimental design for gas-gun experiments. This design allows the Hugoniot properties to be measured with reasonably good accuracy despite the inherent difficulties involved with distended powders. The experiments also provide the first reshock state for the compacted powder. Experiments were conducted at impact velocities of 245, 500, and 711 m/s. A steady shock wave was observed for some of the sample thicknesses, but the remainder were attenuated due to release from the back of the impactor or the edge of the sample. The shock velocity for the powder was found to be quite low, and the propagating shock waves were seen to be very dispersive. The Hugoniot density for the 711 m/s experiment was close to ambient crystal density for tungsten carbide, indicating nearly complete compaction. When compared with quasi-static compaction results for the same material, the dynamic compaction data is seen to be significantly stiffer for the regime over which they overlap. Based on these initial results, recommendations are made for improving the experimental technique and for future work to improve our understanding of powder compaction.

  6. Charged anisotropic Buchdahl solution as an embedding class I spacetime

    NASA Astrophysics Data System (ADS)

    Singh, Ksh. Newton; Pant, Neeraj; Pradhan, N.

    2016-05-01

    We present a new solution of embedding class I describing the interior of a spherically symmetric charged anisotropic stellar configuration. The exact analytic solution has been explored by considering Buchdahl type metric potential g_{rr}. Using this analytic solution, we have discussed various physical aspects of a compact star. The solution is free from central singularities. The solution also satisfies WEC, SEC, NEC and DEC. The compactness parameter 2M/rb as obtained from the solution satisfies the Buchdahl-Andreasson condition. Finally we have compared the calculated masses and radii of well-known compact star candidates like RX J1856.5-3754, XTE J1739-285, PSR B0943+10 and SAX J1808.4-3658 with their observational values.

  7. Charge-ordering transitions without charge differentiation

    NASA Astrophysics Data System (ADS)

    Quan, Yundi; Pardo, Victor; Pickett, Warren

    2013-03-01

    The distorted perovskite nickelate system RNiO3 (R=rare earth except La) undergoes a metal-insulator transition (MIT) at a temperature that varies smoothly with the R ionic radius. This MIT is accompanied by structural transition which leads to two inequivalent Ni sites in the cell, and has been explained by charge ordering (CO): charge is transferred between the Ni1 and Ni2 sites in a long-range ordered fashion. Experimental data on core binding energies, ionic radii, and Mossbauer shifts are interpreted in terms of Ni cation charges of 3 +/- δ with, for example, δ ~ 0.3 for YNiO3. Making use of first principles DFT results and a new approach not invoking integration of the charge density, we find[2] that the Ni 3 d occupation is identical (to high accuracy) for the two Ni sites. We also present results for other compounds (La2VCuO6, YNiO3, CaFeO3, AgNiO2, V4O7), all of which have distinct ``charge states'' that have identical 3 d occupation. This quantitative procedure will be discussed and some implications will be outlined. DOE Grant No. DE-FG02-04ER46111 and Ramon y Cajal Program

  8. Charge Islands Through Tunneling

    NASA Technical Reports Server (NTRS)

    Robinson, Daryl C.

    2002-01-01

    It has been recently reported that the electrical charge in a semiconductive carbon nanotube is not evenly distributed, but rather it is divided into charge "islands." This paper links the aforementioned phenomenon to tunneling and provides further insight into the higher rate of tunneling processes, which makes tunneling devices attractive. This paper also provides a basis for calculating the charge profile over the length of the tube so that nanoscale devices' conductive properties may be fully exploited.

  9. Heat pump charge optimizer

    SciTech Connect

    Drucker, A. S.

    1985-10-15

    The optimum charge in the heating and cooling modes is achieved in a reversible heat pump system by providing a receiver in the indoor section which is sized to store an amount of refrigerant equal to the difference in the optimum charge in each mode. The amount of refrigerant in the receiver is varied in response to the ambient temperature whereby the refrigerant charge is optimized over a range of temperatures.

  10. Solution phase space and conserved charges: A general formulation for charges associated with exact symmetries

    NASA Astrophysics Data System (ADS)

    Hajian, K.; Sheikh-Jabbari, M. M.

    2016-02-01

    We provide a general formulation for calculating conserved charges for solutions to generally covariant gravitational theories with possibly other internal gauge symmetries, in any dimensions and with generic asymptotic behaviors. These solutions are generically specified by a number of exact (continuous, global) symmetries and some parameters. We define "parametric variations" as field perturbations generated by variations of the solution parameters. Employing the covariant phase space method, we establish that the set of these solutions (up to pure gauge transformations) form a phase space, the solution phase space, and that the tangent space of this phase space includes the parametric variations. We then compute conserved charge variations associated with the exact symmetries of the family of solutions, caused by parametric variations. Integrating the charge variations over a path in the solution phase space, we define the conserved charges. In particular, we revisit "black hole entropy as a conserved charge" and the derivation of the first law of black hole thermodynamics. We show that the solution phase space setting enables us to define black hole entropy by an integration over any compact, codminesion-2, smooth spacelike surface encircling the hole, as well as to a natural generalization of Wald and Iyer-Wald analysis to cases involving gauge fields.

  11. Roller compaction of moist pharmaceutical powders.

    PubMed

    Wu, C-Y; Hung, W-L; Miguélez-Morán, A M; Gururajan, B; Seville, J P K

    2010-05-31

    The compression behaviour of powders during roller compaction is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size, shape, moisture content). The moisture content affects the powder properties, such as the flowability and cohesion, but it is not clear how the moisture content will influence the powder compression behaviour during roller compaction. In this study, the effect of moisture contents on roller compaction behaviour of microcrystalline cellulose (MCC, Avicel PH102) was investigated experimentally. MCC samples of different moisture contents were prepared by mixing as-received MCC powder with different amount of water that was sprayed onto the powder bed being agitated in a rotary mixer. The flowability of these samples were evaluated in terms of the poured angle of repose and flow functions. The moist powders were then compacted using the instrumented roller compactor developed at the University of Birmingham. The flow and compression behaviour during roller compaction and the properties of produced ribbons were examined. It has been found that, as the moisture content increases, the flowability of moist MCC powders decreases and the powder becomes more cohesive. As a consequence of non-uniform flow of powder into the compaction zone induced by the friction between powder and side cheek plates, all produced ribbons have a higher density in the middle and lower densities at the edges. For the ribbons made of powders with high moisture contents, different hydration states across the ribbon width were also identified from SEM images. Moreover, it was interesting to find that these ribbons were split into two halves. This is attributed to the reduction in the mechanical strength of moist powder compacts with high moisture contents produced at high compression pressures. PMID:20176096

  12. 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.

  13. Relativistic structure, stability, and gravitational collapse of charged neutron stars

    SciTech Connect

    Ghezzi, Cristian R.

    2005-11-15

    Charged stars have the potential of becoming charged black holes or even naked singularities. We present a set of numerical solutions of the Tolman-Oppenheimer-Volkov equations that represents spherical charged compact stars in hydrostatic equilibrium. The stellar models obtained are evolved forward in time integrating the Einstein-Maxwell field equations. We assume an equation of state of a neutron gas at zero temperature. The charge distribution is taken as being proportional to the rest mass density distribution. The set of solutions present an unstable branch, even with charge-to-mass ratios arbitrarily close to the extremum case. We perform a direct check of the stability of the solutions under strong perturbations and for different values of the charge-to-mass ratio. The stars that are in the stable branch oscillate and do not collapse, while models in the unstable branch collapse directly to form black holes. Stars with a charge greater than or equal to the extreme value explode. When a charged star is suddenly discharged, it does not necessarily collapse to form a black hole. A nonlinear effect that gives rise to the formation of a shell of matter (in supermassive stars), is negligible in the present simulations. The results are in agreement with the third law of black hole thermodynamics and with the cosmic censorship conjecture.

  14. Development of a Compact Plasma Trap for Experimental Beam Physics

    NASA Astrophysics Data System (ADS)

    Takai, Ryota; Enokizono, Hayato; Ito, Kiyokazu; Mizuno, Yasuhiko; Okabe, Kota; Okamoto, Hiromi

    2006-06-01

    A tabletop experimental system has been developed for the study of various collective effects in space-charge-dominated beams. It is based on the recently proposed idea that the dynamic motion of a one-component plasma in a trap can be made physically equivalent to that of a charged-particle beam propagating through a linear transport channel. In this paper, we report on the details of the system and on results of test experiments with a compact Paul trap that is divided into several independent sections. The trap design is carried out in consideration of practical constraints. A Maxwell equation solver is used to calculate the properties of the plasma confinement potential. Experimental observations are compared with numerical data obtained by a tracking simulation code that enables us to approximately predict the three-dimensional trajectories of particles in the system. Low-density N2+ plasmas are employed to examine the basic performance of the multi-section trap. The initial temperature, density and lifetime of a confined plasma are estimated from experiments and simulations.

  15. 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. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. 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 μH, 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

  17. 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 μH, 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.

  18. 77 FR 60475 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-03

    ... address this session of the Council should notify the Federal Bureau Of Investigation (FBI) Compact..., FBI Compact Officer, Module D3, 1000 Custer Hollow Road, Clarksburg, West Virginia 26306, telephone (304) 625-2803, facsimile (304) 625-2868. Dated: September 19, 2012. Gary S. Barron, FBI...

  19. 78 FR 20355 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-04

    ... this session of the Council should notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr... (502) 581-1234. FOR FURTHER INFORMATION CONTACT: Inquiries may be addressed to Mr. Gary S. Barron, FBI...-2803, facsimile (304) 625-2868. Dated: March 26, 2013. Gary S. Barron, FBI Compact Officer,...

  20. 78 FR 61384 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-03

    ... Council should notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr. Gary S. Barron at... (813) 289- 8200. FOR FURTHER INFORMATION CONTACT: Inquiries may be addressed to Mr. Gary S. Barron, FBI...-2803, facsimile (304) 625-2868. Dated: September 25, 2013. Gary S. Barron, FBI Compact...

  1. COMPACT PROTON INJECTOR AND FIRST ACCELERATOR SYSTEM TEST FOR COMPACT PROTON DIELECTRIC WALL CANCER THERAPY ACCELERATOR

    SciTech Connect

    Chen, Y; Guethlein, G; Caporaso, G; Sampayan, S; Blackfield, D; Cook, E; Falabella, S; Harris, J; Hawkins, S; Nelson, S; Poole, B; Richardson, R; Watson, J; Weir, J; Pearson, D

    2009-04-23

    A compact proton accelerator for cancer treatment is being developed by using the high-gradient dielectric insulator wall (DWA) technology [1-4]. We are testing all the essential DWA components, including a compact proton source, on the First Article System Test (FAST). The configuration and progress on the injector and FAST will be presented.

  2. Diagnostics of soil compaction in steppe zone

    NASA Astrophysics Data System (ADS)

    Sorokin, Alexey; Kust, German

    2014-05-01

    Land degradation and desertification are among the major challenges in steppe zone, and leads the risks of food security in affected areas. Soil compaction is one of the basic reasons of degradation of arable land. The processes of soil compaction have different genesis. Knowledge of soil compaction mechanisms and their early diagnostics permit to accurately forecast velocity and degree of degradation processes as well as to undertake effective preventive measures and land reclamation activities. Manifestations of soil compaction and degradation of soil structure due to vertic, alkaline and and mechanical (agro-) compaction, as well as caused by combination of these processes in irrigated and rainfed conditions were studied in four model plots in Krasnodar and Saratov regions of Russia. Typic chernozems, solonetz and kashtanozem solonetz, south chernozem and dark-kashtanozem soils were under investigation. Morphological (mesomorphological, micromorphological and microtomographic) features, as well as number of physical (particle size analyses, water-peptizable clays content (WPC), swelling and shrinking, bulk density and moisture), chemical (humus, pH, CAC, EC), and mineralogical (clay fraction) properties were investigated. Method for grouping soil compaction types by morphological features was proposed. It was shown that: - overcompacted chernozems with vertic features has porosity close to natural chernozems (about 40%), but they had the least pore diameter (7-12 micron) among studied soils. Solonetzic soils had the least amount of "pore-opening" (9%). - irrigation did not lead to the degradation of soil structure on micro-level. - "mechanically" (agro-) compacted soils retained an intra-aggregate porosity. - studied soils are characterized by medium and heavy particle size content (silt [<0.1mm] of 30-60%). Subsoil horizons of chernozems with vertic and alkaline features were the heaviest by particle size content. - the share of WPC to clay ratio was 40% in average, this ratio in vertic and alkaline soils was up to more than 70%. - overcompacted chernozems with vertic features has the swelling degree of 17-25%, all studied soils have the maximum value of swelling degree in subsoil compacted horizon. - humus content varied from 2 to 4%, pH - from 6.9 to 8.2. Studied soils were saturated with basics, Ca of 30 mg*eq/100g and more, Na was more relevant to compacted solonetz and solonetz-like soils (up to 4.3 mg*eq/100g)

  3. Modeling of planetesimal compaction by hot pressing

    NASA Astrophysics Data System (ADS)

    Neumann, W.; Breuer, D.; Spohn, T.

    2014-07-01

    Compaction of initially porous material prior to melting is an important process that has influenced the interior structure and the thermal evolution of planetesimals in their early history. On one hand, compaction decreases the porosity resulting in a reduction of the radius. On the other hand, the loss of porosity results in an increase of the thermal conductivity of the material and, thus, in a more efficient cooling. Porosity loss by hot pressing is the most efficient process of compaction in planetesimals and can be described by creep flow, which depends on temperature and stress. Hot pressing has been repeatedly modeled using a simplified approach, for which the porosity is gradually reduced in some fixed temperature interval between ~650 K and 700 K [see e.g. 1--3]. This approach neglects the dependence of compaction on stress. In the present study [see 4], we compare this ''parametrized'' method with a self-consistent calculation of porosity loss via a ''creep-related'' approach. We use our thermal evolution model from previous studies [5] to model compaction of an initially porous ordinary chondritic body and consider four basic packings of spherical dust grains (simple cubic, orthorhombic, rhombohedral, and body-centered cubic). Depending on the grain packing, we calculate the effective stress and the associated porosity change via the thermally activated creep flow. For comparison, compaction is also modeled by simply reducing the initial porosity linearly to zero between 650 and 700 K. Since we are interested in thermal metamorphism and not melting, we only consider bodies that experience a maximum temperature below the solidus temperature of the metal phase. For the creep related approach, the temperature interval in which compaction takes place depends strongly on the size of the planetesimal and is not fixed as assumed in the parametrized approach. Depending on the radius, the initial grain size, the activation energy, the initial porosity, and the specific packing of the dust grains, the temperature interval lies within 600--1200 K. This finding implies that the parametrized approach strongly overestimates compaction and underestimates the maximal temperature. For the cases considered, the post-compaction porous layer retained at the surface, is a factor of 2.5 to 4.5 thicker for the creep-related approach. The difference in the temperature evolution between the two approaches increases with decreasing radius, and the maximal temperature can deviate by about 40 % for small bodies.

  4. Mixing and compaction temperatures for Superpave mixes

    NASA Astrophysics Data System (ADS)

    Yildirim, Yetkin

    According to Superpave mixture design, gyratory specimens are mixed and compacted at equiviscous binder temperatures corresponding to viscosities of 0.17 and 0.28 Pa.s. respectively. These were the values previously used in the Marshal mix design method to determine optimal mixing and compaction temperatures. In order to estimate the appropriate mixing and compaction temperatures for Superpave mixture design, a temperature-viscosity relationship for the binder needs to be developed (ASTM D 2493, Calculation of Mixing and Compaction Temperatures). The current approach is simple and provides reasonable temperatures for unmodified binders. However, some modified binders have exhibited unreasonably high temperatures for mixing and compaction using this technique. These high temperatures can result in construction problems, damage of asphalt, and production of fumes. Heating asphalt binder to very high temperatures during construction oxidizes the binder and separates the polymer from asphalt binder. It is known that polymer modified asphalt binders have many benefits to the roads, such as; increasing rutting resistance, enhancing low temperature cracking resistance, improving traction, better adhesion and cohesion, elevating tensile strength which are directly related to the service life of the pavement. Therefore, oxidation and separation of the polymer from the asphalt binder results in reduction of the service life. ASTM D 2493 was established for unmodified asphalt binders which are Newtonian fluids at high temperatures. For these materials, viscosity does not depend on shear rate. However, most of the modified asphalt binders exhibit a phenomenon known as pseudoplasticity, where viscosity does depend on shear rate. Thus, at the high shear rates occurring during mixing and compaction, it is not necessary to go to very high temperatures. This research was undertaken to determine the shear rate during compaction such that the effect of this parameter could be included during viscosity measurements. The use of practical shear rates results in reasonable mixing and compaction temperatures for hot mix asphalt design and construction with modified asphalt binders. It was found that application of the shear rate concept, rather than the traditional approach used for unmodified binders, can reduce the mixing and compaction temperatures from between roughly 10 and 30C, depending on the type and the amount of modifier.

  5. Strategy Guideline: Compact Air Distribution Systems

    SciTech Connect

    Burdick, A.

    2013-06-01

    This Strategy Guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward the exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.

  6. 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

  7. Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

    SciTech Connect

    Nihei, K.T.; Nakagawa, S.; Reverdy, F.; Meyer, L.R.; Duranti, L.; Ball, G.

    2010-12-15

    Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.

  8. Space charge stopband correction

    SciTech Connect

    Huang, Xiaobiao; 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. NASA charging analyzer program

    NASA Technical Reports Server (NTRS)

    Cassidy, J. J., III; Harvey, J. M.; Katz, I.; Mandell, M. J.

    1980-01-01

    Computer program predicts electrostatic charging of three dimensional, conducting object partially or completely covered with dielectric films. Program is useful in describing spacecraft charging and material accumulation in plasma environment of magnetosphere. Numerous graphic outputs are implemented. Language is FORTRAN V, for batch execution on 1100-series computer.

  10. Charged particle radiography

    NASA Astrophysics Data System (ADS)

    Morris, C. L.; King, N. S. P.; Kwiatkowski, K.; Mariam, F. G.; Merrill, F. E.; Saunders, A.

    2013-04-01

    New applications of charged particle radiography have been developed over the past two decades that extend the range of radiographic techniques providing high-speed sequences of radiographs of thicker objects with higher effective dose than can be obtained with conventional radiographic techniques. In this paper, we review the motivation and the development of flash radiography and in particular, charged particle radiography.

  11. Charged particle radiography.

    PubMed

    Morris, C L; King, N S P; Kwiatkowski, K; Mariam, F G; Merrill, F E; Saunders, A

    2013-04-01

    New applications of charged particle radiography have been developed over the past two decades that extend the range of radiographic techniques providing high-speed sequences of radiographs of thicker objects with higher effective dose than can be obtained with conventional radiographic techniques. In this paper, we review the motivation and the development of flash radiography and in particular, charged particle radiography. PMID:23481477

  12. Rain Drop Charge Sensor

    NASA Astrophysics Data System (ADS)

    S, Sreekanth T.

    begin{center} Large Large Rain Drop Charge Sensor Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , S. Murali Das (2) *Atmospheric Sciences Division, Centre for Earth Science Studies, Thiruvananthapuram 695011 (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) Kavyam, Manacaud, Thiruvananthapuram 695009 begin{center} ABSTRACT To study the inter-relations with precipitation electricity and precipitation microphysical parameters a rain drop charge sensor was designed and developed at CESS Electronics & Instrumentation Laboratory. Simultaneous measurement of electric charge and fall speed of rain drops could be done using this charge sensor. A cylindrical metal tube (sensor tube) of 30 cm length is placed inside another thick metal cover opened at top and bottom for electromagnetic shielding. Mouth of the sensor tube is exposed and bottom part is covered with metal net in the shielding cover. The instrument is designed in such a way that rain drops can pass only through unhindered inside the sensor tube. When electrically charged rain drops pass through the sensor tube, it is charged to the same magnitude of drop charge but with opposite polarity. The sensor tube is electrically connected the inverted input of a current to voltage converter operational amplifier using op-amp AD549. Since the sensor is electrically connected to the virtual ground of the op-amp, the charge flows to the ground and the generated current is converted to amplified voltage. This output voltage is recorded using a high frequency (1kHz) voltage recorder. From the recorded pulse, charge magnitude, polarity and fall speed of rain drop are calculated. From the fall speed drop diameter also can be calculated. The prototype is now under test running at CESS campus. As the magnitude of charge in rain drops is an indication of accumulated charge in clouds in lightning, this instrument has potential application in the field of risk and disaster management. By knowing the charge magnitude of initial drops from a precipitation event, gross cloud charge can be estimated and necessary precautions can be taken during convective cloud events. Being a site of high lightning incidence in tropics, Kerala state is affected in India and calls for much attention in lightning hazards mitigation. Installing this charge sensor and atmospheric electric field mill, an attempt to a better warning system can be attempted.

  13. Charged topological entanglement entropy

    NASA Astrophysics Data System (ADS)

    Matsuura, Shunji; Wen, Xueda; Hung, Ling-Yan; Ryu, Shinsei

    2016-05-01

    A charged entanglement entropy is a new measure which probes quantum entanglement between different charge sectors. We study symmetry-protected topological (SPT) phases in (2+1)-dimensional space-time by using this charged entanglement entropy. SPT phases are short-range entangled states without topological order and hence cannot be detected by the topological entanglement entropy. We demonstrate that the universal part of the charged entanglement entropy is nonzero for nontrivial SPT phases and therefore it is a useful measure to detect short-range entangled topological phases. We also discuss that the classification of SPT phases based on the charged topological entanglement entropy is related to that of the braiding statistics of quasiparticles.

  14. Spacecraft Charging and Mitigation

    NASA Astrophysics Data System (ADS)

    Denig, William; Cooke, David; Ferguson, Dale

    2010-10-01

    Satellites and spacecraft materials can become charged to tens or even thousands of volts when ions in the space environment collide with spacecraft. This can sometimes cause electrical discharge of differentially or internally charged spacecraft materials, which can adversely affect satellite operations. Additionally, high-energy ions can penetrate spacecraft materials and deposit their energy within sensitive electronics, causing component damage or failure. To consider various approaches for spacecraft charge mitigation, 150 technologists from around the world representing government, academia, and industry met at the 11th Spacecraft Charging Technology Conference (SCTC) in Albuquerque, N. M., on 20-24 September 2010. The conference was held against the backdrop of the apparent charging event of the Galaxy 15 satellite, which some speculate triggered this geosynchronous communications satellite to cease operations, thereby adversely affecting related satellite-reliant communities (see J. Allen, Space Weather, 8, S06008, doi:10.1029/2010SW000588, 2010)

  15. The birthplace of compact groups of galaxies

    NASA Technical Reports Server (NTRS)

    Ramella, Massimo; Diaferio, Antonaldo; Geller, Margaret J.; Huchra, John P.

    1994-01-01

    We use complete redshift surveys to study the redshift neighborhoods of 38 Hickson compact groups (HCGs). Twenty-nine of these HCGs (76%) are embedded in rich looser systems which we call HCG associations. Analysis of the redshift neighborhood of HCGs outside the CfA survey suggests that most HCGs are embedded in more extended physical systems. Rich loose groups extracted from the CfA survey (Ramella et al. (1994)) have physical properties similar to those of the HCG associations. These rich loose groups often contain compact configurations. N-body experiments (Diaferio (1994)) suggest that compact configurations analogous to HCGs form continually during the collapse of rich loose groups. These observational and numerical results suggest that rich loose groups are the birthplace of HCGs.

  16. Compaction dynamics of wet granular packings

    NASA Astrophysics Data System (ADS)

    Vandewalle, Nicolas; Ludewig, Francois; Fiscina, Jorge E.; Lumay, Geoffroy

    2013-03-01

    The extremely slow compaction dynamics of wet granular assemblies has been studied experimentally. The cohesion, due to capillary bridges between neighboring grains, has been tuned using different liquids having specific surface tension values. The characteristic relaxation time for compaction τ grows strongly with cohesion. A kinetic model, based on a free volume kinetic equations and the presence of a capillary energy barrier (due to liquid bridges), is able to reproduce quantitatively the experimental curves. This model allows one to describe the cohesion in wet granular packing. The influence of relative humidity (RH) on the extremely slow compaction dynamics of a granular assembly has also been investigated in the range 20 % - 80 % . Triboelectric and capillary condensation effects have been introduced in the kinetic model. Results confirm the existence of an optimal condition at RH ~ 45 % for minimizing cohesive interactions between glass beads.

  17. Settlement of footing on compacted ash bed

    SciTech Connect

    Ramasamy, G.; Pusadkar, S.S.

    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.

  18. Compaction and Sintering of Mo Powders

    SciTech Connect

    Nunn, Stephen D; Kiggans, Jim; Bryan, Chris

    2013-01-01

    To support the development of Mo-99 production by NorthStar Medical Technologies, LLC, Mo metal powders were evaluated for compaction and sintering characteristics as they relate to Mo-100 accelerator target disk fabrication. Powders having a natural isotope distribution and enriched Mo-100 powder were examined. Various powder characteristics are shown to have an effect on both the compaction and sintering behavior. Natural Mo powders could be cold pressed directly to >90% density. All of the powders, including the Mo-100 samples, could be sintered after cold pressing to >90% density. As an example, a compacted Mo-100 disk reached 89.7% density (9.52 g/cm3) after sintering at 1000 C for 1 hr. in flowing Ar/4%H2. Higher sintering temperatures were required for other powder samples. The relationships between processing conditions and the resulting densities of consolidated Mo disks will be presented.

  19. 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.

  20. Evolution Of Compact Radio-Loud AGNs

    NASA Astrophysics Data System (ADS)

    Kunert-Bajraszewska, M.; Marecki, A.; Thomasson, P.

    2007-05-01

    We present multifrequency radio observations of compact (<20 kpc) radio galaxies and quasars. Based on the FIRST survey we have constructed a flux density limited, new sample of Compact Steep Spectrum (CSS) radio sources and surveyed them with VLA, MERLIN and VLBA. According to the theory of the CSS sources' evolution they are precursors of larger/older radio-loud AGNs. However, our observations revealed a small number of strong candidates for compact faders, which support an alternative idea that some of the small-scale radio sources are short-lived phenomena due to a lack of stable fuelling from the black hole, and never grow up to become large-scale radio objects. Re-ignition of the activity in such objects is not ruled out.

  1. GRAVITATIONALLY FOCUSED DARK MATTER AROUND COMPACT STARS

    SciTech Connect

    Bromley, Benjamin C.

    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.

  2. Explaining compact groups as change alignments

    NASA Technical Reports Server (NTRS)

    Mamon, Gary A.

    1990-01-01

    The physical nature of the apparently densest groups of galaxies, known as compact groups is a topic of some recent controversy, despite the detailed observations of a well-defined catalog of 100 isolated compact groups compiled by Hickson (1982). Whereas many authors have espoused the view that compact groups are bound systems, typically as dense as they appear in projection on the sky (e.g., Williams & Rood 1987; Sulentic 1987; Hickson & Rood 1988), others see them as the result of chance configurations within larger systems, either in 1D (chance alignments: Mamon 1986; Walke & Mamon 1989), or in 3D (transient cores: Rose 1979). As outlined in the companion review to this contribution (Mamon, in these proceedings), the implication of Hickson's compact groups (HCGs) being dense bound systems is that they would then constitute the densest isolated systems of galaxies in the Universe and the privileged site for galaxy interactions. In a previous paper (Mamon 1986), the author reviewed the arguments given for the different theories of compact groups. Since then, a dozen papers have been published on the subject, including a thorough and perceptive review by White (1990), thus more than doubling the amount written on the subject. Here, the author first enumerates the arguments that he brought up in 1986 substantiating the chance alignment hypothesis, then he reviews the current status of the numerous recent arguments arguing against chance alignments and/or for the bound dense group hypothesis (both for the majority of HCGs but not all of them), and finally he reconsiders each one of these anti-chance alignment arguments and shows that, rather than being discredited, the chance alignment hypothesis remains a fully consistent explanation for the nature of compact groups.

  3. DNA Compaction Induced by a Cationic Polymer or Surfactant Impact Gene Expression and DNA Degradation

    PubMed Central

    Ainalem, Marie-Louise; Bartles, Andrew; Muck, Joscha; Dias, Rita S.; Carnerup, Anna M.; Zink, Daniele; Nylander, Tommy

    2014-01-01

    There is an increasing interest in achieving gene regulation in biotechnological and biomedical applications by using synthetic DNA-binding agents. Most studies have so far focused on synthetic sequence-specific DNA-binding agents. Such approaches are relatively complicated and cost intensive and their level of sophistication is not always required, in particular for biotechnological application. Our study is inspired by in vivo data that suggest that DNA compaction might contribute to gene regulation. This study exploits the potential of using synthetic DNA compacting agents that are not sequence-specific to achieve gene regulation for in vitro systems. The semi-synthetic in vitro system we use include common cationic DNA-compacting agents, poly(amido amine) (PAMAM) dendrimers and the surfactant hexadecyltrimethylammonium bromide (CTAB), which we apply to linearized plasmid DNA encoding for the luciferase reporter gene. We show that complexing the DNA with either of the cationic agents leads to gene expression inhibition in a manner that depends on the extent of compaction. This is demonstrated by using a coupled in vitro transcription-translation system. We show that compaction can also protect DNA against degradation in a dose-dependent manner. Furthermore, our study shows that these effects are reversible and DNA can be released from the complexes. Release of DNA leads to restoration of gene expression and makes the DNA susceptible to degradation by Dnase. A highly charged polyelectrolyte, heparin, is needed to release DNA from dendrimers, while DNA complexed with CTAB dissociates with the non-ionic surfactant C12E5. Our results demonstrate the relation between DNA compaction by non-specific DNA-binding agents and gene expression and gene regulation can be achieved in vitro systems in a reliable dose-dependent and reversible manner. PMID:24671109

  4. Multifunctional compact zwitterionic ligands for preparing robust biocompatible semiconductor quantum dots and gold nanoparticles.

    PubMed

    Susumu, Kimihiro; Oh, Eunkeu; Delehanty, James B; Blanco-Canosa, Juan B; Johnson, Brandy J; Jain, Vaibhav; Hervey, William Judson; Algar, W Russ; Boeneman, Kelly; Dawson, Philip E; Medintz, Igor L

    2011-06-22

    We describe the synthesis of a series of four different ligands which are used to prepare hydrophilic, biocompatible luminescent quantum dots (QDs) and gold nanoparticles (AuNPs). Overall, the ligands are designed to be compact while still imparting a zwitterionic character to the NPs. Ligands are synthesized appended to a bidentate dihydrolipoic acid- (DHLA) anchor group, allowing for high-affinity NP attachment, and simultaneously incorporate tertiary amines along with carboxyl and/or hydroxyl groups. These are placed in close proximity within the ligand structure and their capacity for joint ionization imparts the requisite zwitterionic nature to the nanocrystal. QDs functionalized with the four different compact ligands were subjected to extensive physical characterization including surface charge, wettability, hydrodynamic size, and tolerance to a wide pH range or high salt concentration over time. The utility of the compact ligand coated QDs was further examined by testing of direct conjugation to polyhistidine-appended protein and peptides, aqueous covalent-coupling chemistry, and the ability to engage in Förster resonance energy transfer (FRET). Conjugating cell penetrating peptides to the compact ligand coated QD series facilitated their rapid and efficient cellular uptake, while subsequent cytotoxicity tests showed no apparent decreases in cell viability. In vivo biocompatibility was also demonstrated by microinjecting the compact ligand coated QDs into cells and monitoring their stability over time. Inherent benefits of the ligand design could be extended beyond QDs as AuNPs functionalized with the same compact ligand series showed similar colloidal properties. The strong potential of these ligands to expand NP capabilities in many biological applications is highlighted. PMID:21612225

  5. 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.

  6. Compact zoom lens for stereoscopic television

    NASA Astrophysics Data System (ADS)

    Scheiwiller, Peter M.; Murphy, Sean; Dumbreck, Andrew A.

    1991-08-01

    This paper describes the on-going development of a compact zoom lens specifically for stereoscopic television in nuclear environments. Custom-designed optics in radiation-tolerant glass provide a focal length of 12.5 mm to 36 mm with a package length of less than 110 mm. A novel method of encoding the position of the lens elements allows for very compact motorization, and a precision mechanism designed to overcome backlash ensures the stability of picture matching. The position of the lens elements is controlled by a 16-bit microcontroller, and the control strategy allows focus and convergence to be maintained to a high degree of accuracy during zooming.

  7. Compaction by impact of unconsolidated lunar fines

    NASA Technical Reports Server (NTRS)

    Ahrens, T. J.

    1975-01-01

    An investigation was conducted concerning the macroscopic irreversible partial compaction of terrestrial or lunar fines. A sample material (70051), assumed to be typical of the fines in the unconsolidated material of the lunar regolith, was used in the experiments. Tests were also carried out with powdered Vacaville basalt. Release adiabate and Hugoniot measurements were conducted. It was found that the dynamic stresses required for irreversible compaction of lunar fines on the moon are significantly lower than the values inferred from the shock recovery experiments conducted by Christie et al. (1973).

  8. Remote vacuum compaction of compressible hazardous waste

    DOEpatents

    Coyne, M.J.; Fiscus, G.M.; Sammel, A.G.

    1998-10-06

    A system is described for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut. 8 figs.

  9. 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.

  10. Compact spectrometer based on concave grating

    NASA Astrophysics Data System (ADS)

    Zheng, Feng; Liu, Liying; Zhang, Guoyu; Huan, Kewei; Li, Ye; Shi, Xiaoguang

    2015-11-01

    In this paper, the compact spectrometer has been designed and implemented with concave grating. By using the holographic corrected concave grating, the compact spectrometer without movable parts, with a fixed grating and an array detector, could obtain a relative high spectral resolution in a wide spectral range. Then, the spectral resolution has been estimated by the slit function. The spectral resolution (ΔFWHM) is smaller than 5nm from 300nm to 1100nm. It is very suitable for photometry, colorimetry, and radiometry.

  11. Compact, Robust Chips Integrate Optical Functions

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Located in Bozeman, Montana, AdvR Inc. has been an active partner in NASA's Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs. Langley Research Center engineers partnered with AdvR through the SBIR program to develop new, compact, lightweight electro-optic components for remote sensing systems. While the primary customer for this technology will be NASA, AdvR foresees additional uses for its NASA-derived circuit chip in the fields of academic and industrial research anywhere that compact, low-cost, stabilized single-frequency lasers are needed.

  12. Nondestructive evaluation of compacted clayey soils

    NASA Astrophysics Data System (ADS)

    Inci, Gokhan

    Compacted clayey soils are analyzed using nondestructive testing methods. Ultrasonic testing and image analysis are used as nondestructive testing techniques. Tests were conducted on three clayey soils with low to high plasticities. The soils are compacted and then allowed to dry or subjected to wetting and drying cycles subsequent to compaction. Ultrasonic tests are performed to determine small strain elastic properties of soils during drying. Image analysis techniques are used to determine large strains and cracking behavior of soils during wetting and drying cycles. Finally, numerical methods are used to simulate large and small strain soil behavior. Ultrasonic testing can be used effectively to determine compaction characteristics of soils. Through transmission can be applicable in the laboratory or on recovered field samples while surface transmission can be used in the field. Variation of P-wave velocity is similar to variation of dry density for the test soils. Increasing compactive effort cause increases in measured wave velocity. Variations of elastic parameters during drying are investigated. More variation was observed for soils compacted with low compaction effort and high water contents. Five elastic parameters of cross-anisotropy are calculated from wave velocity measurements on cubical samples with oblique cuts. Constrained, Young's, and shear moduli increase, while Poisson's ratios decrease during drying. Starting with isotropy assumption, empirical formulas are used to calculate the shear moduli and results are compared with experimental shear modulus values obtained using the theory of elasticity. A new formulation is developed to compute shear modulus variation with saturation. Behavior of compacted clayey soils during wetting and drying was also investigated. High plasticity-fine grained soils tend to shrink and crack more during drying. Cracks of these soils tend to heal and close during wetting cycles. Cracking and healing are less for medium and low plasticity soils. Cracking is observed at relatively low suction levels for all soil types. Cracking is quantified using image analysis techniques. Finite element models are successfully used to make predictions on small strainwave propagation and fracture potential of soils. Transducer size has significant effect on surface arrangement arrival times and water content profile has significant effect on fracture potential.

  13. Theta constants, moduli, and compact riemann surfaces.

    PubMed

    Farkas, H M

    1969-02-01

    One of the classical tools for the study of moduli of compact Riemann surfaces is the Riemann theta function. Preliminary results were announced earlier(1) which established relations between two kinds of theta constants on a compact Riemann surface of genus 2. In this note we generalize the results there obtained. The main theorem is as follows:A sufficient condition for [Formula: see text] to be independent of [Formula: see text] is that [Formula: see text] for the 2(g-2)(2(g-1) - 1) characteristics [Formula: see text] where [Formula: see text] ranges over all odd g - 1 characteristics. PMID:16578693

  14. 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.

  15. Construction of weighted upwind compact scheme

    NASA Astrophysics Data System (ADS)

    Wang, Zhengjie

    Enormous endeavor has been devoted in spatial high order high resolution schemes in more than twenty five years previously, like total variation diminishing (TVD), essentially non-oscillatory scheme, weighted essentially non-oscillatory scheme for finite difference, and Discontinuous Galerkin methods for finite element and the finite volume. In this dissertation, a high order finite difference Weighted Upwind Compact Scheme has been constructed by dissipation and dispersion analysis. Secondly, a new method to construct global weights has been tested. Thirdly, a methodology to compromise dissipation and dispersion in constructing Weighted Upwind Compact Scheme has been derived. Finally, several numerical test cases have been shown.

  16. Remote vacuum compaction of compressible hazardous waste

    DOEpatents

    Coyne, Martin J.; Fiscus, Gregory M.; Sammel, Alfred G.

    1998-01-01

    A system for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut.

  17. 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).

  18. Relativistically spinning charged sphere

    SciTech Connect

    Lynden-Bell, D.

    2004-11-15

    When the equatorial spin velocity v of a charged conducting sphere approaches c, the Lorentz force causes a remarkable rearrangement of the total charge q. Charge of that sign is confined to a narrow equatorial belt at latitudes b{<=}{radical}(3)(1-v{sup 2}/c{sup 2}){sup 1/2} while charge of the opposite sign occupies most of the sphere's surface. The change in field structure is shown to be a growing contribution of the 'magic' electromagnetic field of the charged Kerr-Newman black hole with Newton's G set to zero. The total charge within the narrow equatorial belt grows as (1-v{sup 2}/c{sup 2}){sup -(1/4)} and tends to infinity as v approaches c. The electromagnetic field, Poynting vector, field angular momentum, and field energy are calculated for these configurations. Gyromagnetic ratio, g factor, and electromagnetic mass are illustrated in terms of a 19th century electron model. Classical models with no spin had the small classical electron radius e{sup 2}/mc{sup 2}{approx} a hundredth of the Compton wavelength, but models with spin take that larger size but are so relativistically concentrated to the equator that most of their mass is electromagnetic. The method of images at inverse points of the sphere is shown to extend to charges at points with imaginary coordinates.

  19. 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.

  20. Mitotic chromosome compaction via active loop extrusion

    NASA Astrophysics Data System (ADS)

    Goloborodko, Anton; Imakaev, Maxim; Marko, John; Mirny, Leonid; MIT-Northwestern Team

    During cell division, two copies of each chromosome are segregated from each other and compacted more than hundred-fold into the canonical X-shaped structures. According to earlier microscopic observations and the recent Hi-C study, chromosomes are compacted into arrays of consecutive loops of ~100 kilobases. Mechanisms that lead to formation of such loop arrays are largely unknown. Here we propose that, during cell division, chromosomes can be compacted by enzymes that extrude loops on chromatin fibers. First, we use computer simulations and analytical modeling to show that a system of loop-extruding enzymes on a chromatin fiber self-organizes into an array of consecutive dynamic loops. Second, we model the process of loop extrusion in 3D and show that, coupled with the topo II strand-passing activity, it leads to robust compaction and segregation of sister chromatids. This mechanism of chromosomal condensation and segregation does not require additional proteins or specific DNA markup and is robust against variations in the number and properties of such loop extruding enzymes. Work at NU was supported by the NSF through Grants DMR-1206868 and MCB-1022117, and by the NIH through Grants GM105847 and CA193419. Work at MIT was supported by the NIH through Grants GM114190 R01HG003143.

  1. Compact Hydraulic Excavator and Support Unit

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1985-01-01

    Continuous-coal-mining machine maneuverable. Hydraulic coal excavator combined with chock, or roof-support structure, in self-contained unit that moves itself forward as it removes coal from seam. Unlike previous such units, new machine compact enough to be easily maneuverable; even makes small-radius right-angle turns.

  2. 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.).

  3. COMPACT COILED DENUDER FOR ATMOSPHERIC SAMPLING

    EPA Science Inventory

    A compact coiled denuder has been designed and its performance evaluated both theoretically and experimentally. he design is based on special features of laminar flow in a curved tube, which significantly enhance the mass transfer Sherwood number governing gas collection at the w...

  4. Compaction effects of radiation on Zerodur

    NASA Astrophysics Data System (ADS)

    Davis, Mark J.; Fainberg, Jakob

    2003-12-01

    All materials undergo some degree of compaction when exposed to radiation. Multi-component materials are more susceptible to this effect than single-component materials (e.g., fused silica). Nonetheless, the much lower expansion characteristics of multi-component materials--such as the ultra-low expansion glass-ceramic Zerodur-- preserves the attractiveness of such materials for applications that require superior dimensional stability. In this study, we present a reanalysis of experimental data describing the compaction effects of primarily electron radiation on Zerodur. These data include high-dose, high dose-rate bulk density measurements as well as lower-dose, interferometrically-measured surface figure changes. We show that previous attempts to deduce linear compaction from figure changes are in error and in fact have precluded earlier attempts to predict radiation effects for an arbitrary optical geometry. By interpreting surface figure measurements in light of a more relevant physical model--a simplified bimetal equation--we are able for the first time to accurately predict expected deformation as a function of prescribed dose for both laboratory and space-based experiments. Moreover, we show that a real discrepancy exists between compaction estimates from bulk density experiments and those from surface figure measurements.

  5. Soil compaction across the old rotation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluating soil compaction levels across the Old Rotation, the world’s oldest continuous cotton (Gossypium hirsutum L.) experiment, has not been conducted since the experiment transitioned to conservation tillage and high residue cover crops with and without irrigation. Our objective was to charact...

  6. Holographic Compact Disk Read-Only Memories

    NASA Technical Reports Server (NTRS)

    Liu, Tsuen-Hsi

    1996-01-01

    Compact disk read-only memories (CD-ROMs) of proposed type store digital data in volume holograms instead of in surface differentially reflective elements. Holographic CD-ROM consist largely of parts similar to those used in conventional CD-ROMs. However, achieves 10 or more times data-storage capacity and throughput by use of wavelength-multiplexing/volume-hologram scheme.

  7. Pathway to a compact SASE FEL device

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  8. 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.

  9. 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.

  10. 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.

  11. 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)

  12. Compact CCD Guider Camera for Magellan

    NASA Astrophysics Data System (ADS)

    Burley, G.; Thompson, I.; Hull, C.

    The Magellan guider camera uses a low-noise frame transfer CCD with a digital signal processor based controller. The electronics feature a compact, simple design, optimized for fast settling times and rapid readout rate. The camera operates (nominally) at -20 ºC with thermoelectric cooling. Multiple operating modes are supported, with software selectable binning, exposure times, and subrastering

  13. 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

  14. Compact continuum brain model for human electroencephalogram

    NASA Astrophysics Data System (ADS)

    Kim, J. W.; Shin, H.-B.; Robinson, P. A.

    2007-12-01

    A low-dimensional, compact brain model has recently been developed based on physiologically based mean-field continuum formulation of electric activity of the brain. The essential feature of the new compact model is a second order time-delayed differential equation that has physiologically plausible terms, such as rapid corticocortical feedback and delayed feedback via extracortical pathways. Due to its compact form, the model facilitates insight into complex brain dynamics via standard linear and nonlinear techniques. The model successfully reproduces many features of previous models and experiments. For example, experimentally observed typical rhythms of electroencephalogram (EEG) signals are reproduced in a physiologically plausible parameter region. In the nonlinear regime, onsets of seizures, which often develop into limit cycles, are illustrated by modulating model parameters. It is also shown that a hysteresis can occur when the system has multiple attractors. As a further illustration of this approach, power spectra of the model are fitted to those of sleep EEGs of two subjects (one with apnea, the other with narcolepsy). The model parameters obtained from the fittings show good matches with previous literature. Our results suggest that the compact model can provide a theoretical basis for analyzing complex EEG signals.

  15. 28 CFR 2.107 - Interstate Compact.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Interstate Compact. 2.107 Section 2.107 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT OF PRISONERS, YOUTH OFFENDERS, AND JUVENILE DELINQUENTS District of Columbia Code: Prisoners and Parolees §...

  16. Compact Electric- And Magnetic-Field Sensor

    NASA Technical Reports Server (NTRS)

    Winterhalter, Daniel; Smith, Edward

    1994-01-01

    Compact sensor measures both electric and magnetic fields. Includes both short electric-field dipole and search-coil magnetometer. Three mounted orthogonally providing triaxial measurements of electromagnetic field at frequencies ranging from near 0 to about 10 kHz.

  17. Vacuum magnetic field structure of compact torii

    SciTech Connect

    Sobehart, J.R. Buenos Aires, Argentina )

    1990-01-01

    A new class of axisymmetric vacuum field solutions of the Grad--Shafranov equation, which is suitable for describing the field external to a compact torus equilibrium, is presented. In particular, solutions that match straight field lines at infinity are studied.

  18. Magnetic diagnostic responses for compact stellarators

    SciTech Connect

    Steven P. Hirshman; Edward A. Lazarus; James D. Hanson; Stephen F. Knowlton; Lang L. Lao,

    2004-02-01

    The formulation of magnetic diagnostic response functions for a 3-dimensional stellarator plasma is described. Reciprocity relations are used to compute unique response functions for each type of magnetic diagnostic. Green's function response tables (databases) are generated from which both external and internal plasma current contributions to diagnostic signals can be rapidly computed. Applications to compact stellarators are described.

  19. Compact Disc Cataloging Product User Survey.

    ERIC Educational Resources Information Center

    Whitehair, David E.

    In late 1988, a compact disc cataloging product was introduced to the library market. In order to learn more about the needs of current users, a survey was developed to include questions concerning software features and operations, software enhancements, bibliographic and authority subsets, and hardware issues. This study was conducted among all…

  20. Compact imaging spectrometer utilizing immersed gratings

    DOEpatents

    Lerner, Scott A.

    2005-12-20

    A compact imaging spectrometer comprising an entrance slit for directing light, lens means for receiving the light, refracting the light, and focusing the light; an immersed diffraction grating that receives the light from the lens means and defracts the light, the immersed diffraction grating directing the detracted light back to the lens means; and a detector that receives the light from the lens means.

  1. Compact Translating-Head Magnetic Memories

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.

    1992-01-01

    Stationary magnetic media stores information at densities up to 6.5 Gb/cm(Sup 2). High-density memory devices combine features of advanced rotating-disk magnetic recording and playback systems with compact two-axis high-acceleration linear actuators. New devices weigh less, occupy less space, and consume less power than disk and tape recorders.

  2. 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.

  3. Realisation of a compact methane optical clock

    SciTech Connect

    Gubin, M A; Kireev, A N; Konyashchenko, A V; Kryukov, P G; Tausenev, A V; Tyurikov, D A; Shelkovnikov, A S

    2008-07-31

    A compact optical clock based on a double-mode He-Ne/CH{sub 4} optical frequency standard and a femtosecond Er{sup 3+} fibre laser is realised and its stability against a commercial hydrogen frequency standard is measured. (letters)

  4. The Boston Compact: A Teaching Case.

    ERIC Educational Resources Information Center

    Farrar, Eleanor

    The Boston Compact, signed in September 1982, is a formal agreement between the Boston School Department and members of the business community to collaborate in making new educational and employment opportunities available to the city's high school students. Co-signers agreed to the following: (1) assist in developing private sector initiatives in…

  5. Compact MIMO Antenna for LTE Handsets

    NASA Astrophysics Data System (ADS)

    Wong, H. S.; Kibria, S.; Mansor, M. F. B.; Islam, M. T.

    2015-11-01

    This paper presents a compact MIMO antenna for LTE 700, LTE 2300 and LTE 2500 applications. The antenna is configured by two symmetrical quarter wavelength meandered lines on the front side and a slotted ground plane at the back side. An decoupling patch is used to achieve good isolation between two symmetrical quarter wavelength meandered lines.

  6. Compact range for variable-zone measurements

    DOEpatents

    Burnside, W.D.; Rudduck, R.C.; Yu, J.S.

    1987-02-27

    A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector. 2 figs.

  7. Compact range for variable-zone measurements

    DOEpatents

    Burnside, Walter D.; Rudduck, Roger C.; Yu, Jiunn S.

    1988-01-01

    A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector.

  8. 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

  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. Benchmark Airport Charges

    NASA Technical Reports Server (NTRS)

    de Wit, A.; Cohn, N.

    1999-01-01

    The Netherlands Directorate General of Civil Aviation (DGCA) commissioned Hague Consulting Group (HCG) to complete a benchmark study of airport charges at twenty eight airports in Europe and around the world, based on 1996 charges. This study followed previous DGCA research on the topic but included more airports in much more detail. The main purpose of this new benchmark study was to provide insight into the levels and types of airport charges worldwide and into recent changes in airport charge policy and structure. This paper describes the 1996 analysis. It is intended that this work be repeated every year in order to follow developing trends and provide the most up-to-date information possible.

  11. 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.

  12. Charged lepton flavour violation

    NASA Astrophysics Data System (ADS)

    Hirsch, M.

    2011-08-01

    The observation of neutrino oscillations has demonstrated that individual lepton numbers are not conserved. However, lepton flavour violation has so far not been seen in processes involving charged leptons, despite many models beyond the standard model predicting sizeable rates for decays such as ??e+?. In this talk charged lepton flavour oscillations is briefly summarized from a theoretical point of view: (i) It is stressed that observing charged lepton flavour oscillations in different final states is important to distinguish between different models; (ii) SUSYSupersymmetric lepton flavour violation in seesaw models is briefly outlined; (iii) the impact of non-abelian symmetries for predictions of charged lepton flavour oscillations is discussed and, finally (iv) the status of the exotic decay ??e+ Majoron is summarized.

  13. FABRICATION OF URANIUM OXYCARBIDE KERNELS AND COMPACTS FOR HTR FUEL

    SciTech Connect

    Dr. Jeffrey A. Phillips; Eric L. Shaber; Scott G. Nagley

    2012-10-01

    As part of the program to demonstrate tristructural isotropic (TRISO)-coated fuel for the Next Generation Nuclear Plant (NGNP), Advanced Gas Reactor (AGR) fuel is being irradiation tested in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). This testing has led to improved kernel fabrication techniques, the formation of TRISO fuel particles, and upgrades to the overcoating, compaction, and heat treatment processes. Combined, these improvements provide a fuel manufacturing process that meets the stringent requirements associated with testing in the AGR experimentation program. Researchers at Idaho National Laboratory (INL) are working in conjunction with a team from Babcock and Wilcox (B&W) and Oak Ridge National Laboratory (ORNL) to (a) improve the quality of uranium oxycarbide (UCO) fuel kernels, (b) deposit TRISO layers to produce a fuel that meets or exceeds the standard developed by German researches in the 1980s, and (c) develop a process to overcoat TRISO particles with the same matrix material, but applies it with water using equipment previously and successfully employed in the pharmaceutical industry. A primary goal of this work is to simplify the process, making it more robust and repeatable while relying less on operator technique than prior overcoating efforts. A secondary goal is to improve first-pass yields to greater than 95% through the use of established technology and equipment. In the first test, called “AGR-1,” graphite compacts containing approximately 300,000 coated particles were irradiated from December 2006 to November 2009. The AGR-1 fuel was designed to closely replicate many of the properties of German TRISO-coated particles, thought to be important for good fuel performance. No release of gaseous fission product, indicative of particle coating failure, was detected in the nearly 3-year irradiation to a peak burn up of 19.6% at a time-average temperature of 1038–1121°C. Before fabricating AGR-2 fuel, each fabrication process was improved and changed. Changes to the kernel fabrication process included replacing the carbon black powder feed with a surface-modified carbon slurry and shortening the sintering schedule. AGR-2 TRISO particles were produced in a 6-inch diameter coater using a charge size about 21-times that of the 2-inch diameter coater used to coat AGR-1 particles. The compacting process was changed to increase matrix density and throughput by increasing the temperature and pressure of pressing and using a different type of press. AGR-2 fuel began irradiation in the ATR in late spring 2010.

  14. Charged anisotropic matter with linear or nonlinear equation of state

    SciTech Connect

    Varela, Victor; Rahaman, Farook; Ray, Saibal; Chakraborty, Koushik; Kalam, Mehedi

    2010-08-15

    Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplifications achieved with the introduction of electric charge were noticed as well. We deal with self-gravitating, charged, anisotropic fluids and get even more flexibility in solving the Einstein-Maxwell equations. In order to discuss analytical solutions we extend Krori and Barua's method to include pressure anisotropy and linear or nonlinear equations of state. The field equations are reduced to a system of three algebraic equations for the anisotropic pressures as well as matter and electrostatic energy densities. Attention is paid to compact sources characterized by positive matter density and positive radial pressure. Arising solutions satisfy the energy conditions of general relativity. Spheres with vanishing net charge contain fluid elements with unbounded proper charge density located at the fluid-vacuum interface. Notably the electric force acting on these fluid elements is finite, although the acting electric field is zero. Net charges can be huge (10{sup 19}C) and maximum electric field intensities are very large (10{sup 23}-10{sup 24} statvolt/cm) even in the case of zero net charge. Inward-directed fluid forces caused by pressure anisotropy may allow equilibrium configurations with larger net charges and electric field intensities than those found in studies of charged isotropic fluids. Links of these results with charged strange quark stars as well as models of dark matter including massive charged particles are highlighted. The van der Waals equation of state leading to matter densities constrained by cubic polynomial equations is briefly considered. The fundamental question of stability is left open.

  15. Left ventricular non-compaction cardiomyopathy.

    PubMed

    Towbin, Jeffrey A; Lorts, Angela; Jefferies, John Lynn

    2015-08-22

    Left ventricular non-compaction, the most recently classified form of cardiomyopathy, is characterised by abnormal trabeculations in the left ventricle, most frequently at the apex. It can be associated with left ventricular dilation or hypertrophy, systolic or diastolic dysfunction, or both, or various forms of congenital heart disease. Affected individuals are at risk of left or right ventricular failure, or both. Heart failure symptoms can be induced by exercise or be persistent at rest, but many patients are asymptomatic. Patients on chronic treatment for compensated heart failure sometimes present acutely with decompensated heart failure. Other life-threatening risks of left ventricular non-compaction are ventricular arrhythmias or complete atrioventricular block, presenting clinically as syncope, and sudden death. Genetic inheritance arises in at least 30-50% of patients, and several genes that cause left ventricular non-compaction have been identified. These genes seem generally to encode sarcomeric (contractile apparatus) or cytoskeletal proteins, although, in the case of left ventricular non-compaction with congenital heart disease, disturbance of the NOTCH signalling pathway seems part of a final common pathway for this form of the disease. Disrupted mitochondrial function and metabolic abnormalities have a causal role too. Treatments focus on improvement of cardiac efficiency and reduction of mechanical stress in patients with systolic dysfunction. Further, treatment of arrhythmia and implantation of an automatic implantable cardioverter-defibrillator for prevention of sudden death are mainstays of therapy when deemed necessary and appropriate. Patients with left ventricular non-compaction and congenital heart disease often need surgical or catheter-based interventions. Despite progress in diagnosis and treatment in the past 10 years, understanding of the disorder and outcomes need to be improved. PMID:25865865

  16. Modeling of spacecraft charging

    NASA Technical Reports Server (NTRS)

    Whipple, E. C., Jr.

    1977-01-01

    Three types of modeling of spacecraft charging are discussed: statistical models, parametric models, and physical models. Local time dependence of circuit upset for DoD and communication satellites, and electron current to a sphere with an assumed Debye potential distribution are presented. Four regions were involved in spacecraft charging: (1) undisturbed plasma, (2) plasma sheath region, (3) spacecraft surface, and (4) spacecraft equivalent circuit.

  17. 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.

  18. Proppant charge and method

    SciTech Connect

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

    1984-04-17

    A method is provided for propping a fracture in a subterranean formation which comprises injecting into a subterranean well a suspension in a carrier fluid of a pre-cured proppant charge, the pre-cured proppant charge being pre-cured prior to injection into the well, and comprising prior to injection into the well, resin coated sand particles most of which are composed of a single substrate particle with a thermoset resite coating thereon, the resite coating being one which, when it is the resin coating on sand particles of a proppant charge, produces a charge wherein at least one of: (a) the Conductivity Ratio thereof, throughout a given closure stress range, is greater than that of a charge of the uncoated sand particles having substantially the same particle size distribution; or (b) the Permeability Ratio thereof, throughout the stress range of about 2,000 to about 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 being at least one of: (1) a resole; or (2) a novolac.

  19. 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.

  20. 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.

  1. Design and testing of focusing magnets for a compact electron linac

    NASA Astrophysics Data System (ADS)

    Chen, Qushan; Qin, Bin; Liu, Kaifeng; Liu, Xu; Fu, Qiang; Tan, Ping; Hu, Tongning; Pei, Yuanji

    2015-10-01

    Solenoid field errors have great influence on electron beam qualities. In this paper, design and testing of high precision solenoids for a compact electron linac is presented. We proposed an efficient and practical method to solve the peak field of the solenoid for relativistic electron beams based on the reduced envelope equation. Beam dynamics involving space charge force were performed to predict the focusing effects. Detailed optimization methods were introduced to achieve an ultra-compact configuration as well as high accuracy, with the help of the POISSON and OPERA packages. Efforts were attempted to restrain system errors in the off-line testing, which showed the short lens and the main solenoid produced a peak field of 0.13 T and 0.21 T respectively. Data analysis involving central and off axes was carried out and demonstrated that the testing results fitted well with the design.

  2. A compact time-of-flight mass spectrometer for ion source characterization

    SciTech Connect

    Chen, L. Wan, X.; Jin, D. Z.; Tan, X. H.; Huang, Z. X.; Tan, G. B.

    2015-03-15

    A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters.

  3. Radioactive decays of highly-charged ions

    NASA Astrophysics Data System (ADS)

    Gao, B. S.; Najafi, M. A.; Atanasov, D. R.; Blaum, K.; Bosch, F.; Brandau, C.; Chen, X. C.; Dillmann, I.; Dimopoulou, Ch.; Faestermann, Th.; Geissel, H.; Gernhäuser, R.; Hillenbrand, P.-M.; Kovalenko, O.; Kozhuharov, C.; Litvinov, S. A.; Litvinov, Yu. A.; Maier, L.; Nolden, F.; Piotrowski, J.; Sanjari, M. S.; Scheidenberger, C.; Spillmann, U.; Steck, M.; Stöhlker, Th.; Trageser, Ch.; Tu, X. L.; Weick, H.; Winckler, N.; Xu, H. S.; Yamaguchi, T.; Yan, X. L.; Zhang, Y. H.; Zhou, X. H.

    2015-05-01

    Access to stored and cooled highly-charged radionuclides offers unprecedented opportunities to perform high-precision investigations of their decays. Since the few-electron ions, e.g. hydrogen- or helium-like ions, are quantum mechanical systems with clear electronic ground state configurations, the decay studies of such ions are performed under well-defined conditions and allow for addressing fundamental aspects of the decay process. Presented here is a compact review of the relevant experiments conducted at the Experimental Storage Ring ESR of GSI. A particular emphasis is given to the investigations of the two-body beta decay, namely the bound-state β-decay and its time-mirrored counterpart, orbital electron-capture.

  4. Charged particle distributions in Jupiter's magnetosphere

    NASA Technical Reports Server (NTRS)

    Divine, N.; Garrett, H. B.

    1983-01-01

    In situ data from the Pioneer and Voyager spacecraft, supplemented by earth-based observations and theoretical considerations, are used as the basis for the present quantitative, compact model of the 1 eV-several MeV charged particle distribution in the Jovian magnetosphere. The thermal plasma parameters of convection speed, number density, and characteristic energy, are specified as functions of position for electrons and for the ion species H(+), O(+), O(2+), S(+), S(2+), S(3+), and Na(+). Major features of the magnetic field, thermal plasma, and trapped particle distributions, are modeled and results for each plasma region are compared with observed spectra. Comparisons show that the model represents the data to within a factor of 2 + or - 1, except where time variations are significant. Practical applications of the model to spacecraft near Jupiter are given.

  5. Study of Underwater Shock Compaction Device for Compaction of Titanium Diboride Powder

    NASA Astrophysics Data System (ADS)

    Kennedy, G. B.; Kim, Y. K.; Hokamoto, K.; Itoh, S.

    2007-06-01

    Shock compaction for powders has been used to study bulk consolidation of powder materials. Shock compaction has the advantage of processing at low temperatures and short duration to limit effects of high temperatures for long times, such as increased grain size and high energy cost. Many methods of shock loading of powders have been employed: direct contact with explosive, explosively driven flyer plates, and flyer plates launched with light gas or propellant gun. Another method, using explosives to create a shockwave in water that is in contact with a powder container, has been used extensively at Kumamoto University. This work presents a study of the development of the underwater shockwave device and investigates the water container geometry for control of parameters for shockwave peak pressure, duration, and distribution through the powder compaction process. Results of simulations for optimization of shock compaction properties are presented along with measurements from input and propagated manganin gauge pressure measurements obtained from underwater shock compaction of titanium diboride. The hardness measurements throughout the bulk of the shock compacted titanium diboride are discussed.

  6. Study of Underwater Shock Compaction Device for Compaction of Titanium Diboride

    NASA Astrophysics Data System (ADS)

    Kennedy, G. B.; Kim, Y. K.; Hokamoto, K.; Itoh, S.

    2007-12-01

    Shock compaction for powders has been used to study bulk consolidation of powder materials. Shock compaction has the advantage of processing at low temperatures and short duration to limit effects of high temperatures for long times, such as increased grain size and high energy cost. Many methods of shock loading of powders have been employed: direct contact with explosive, explosively driven flyer plates, and flyer plates launched with light gas or propellant gun. Another method, using explosives to create a shockwave in water that is then contact with a powder container, has been used extensively at Kumamoto University. This work presents a study of the development of the underwater shockwave device and investigates the water container geometry for control of parameters for shockwave peak pressure, duration, and distribution through the powder compaction process. Results of simulations for optimization of shock compaction properties are presented along with measurements from manganin gauge pressure measurements obtained from underwater shock compaction of titanium diboride. The goal of this work is to develop a better understanding of the entire compaction process to utilize the in-situ data to modify numerical simulations to predict performance.

  7. Soil microbial activity as influenced by compaction and straw mulching

    NASA Astrophysics Data System (ADS)

    Siczek, A.; Frąc, M.

    2012-02-01

    Field study was performed on Haplic Luvisol soil to determine the effects of soil compaction and straw mulching on microbial parameters of soil under soybean. Treatments with different compaction were established on unmulched and mulched with straw soil. The effect of soil compaction and straw mulching on the total bacteria number and activities of dehydrogenases, protease, alkaline and acid phosphatases was studied. The results of study indicated the decrease of enzymes activities in strongly compacted soil and their increase in medium compacted soil as compared to no-compacted treatment. Mulch application caused stimulation of the bacteria total number and enzymatic activity in the soil under all compaction levels. Compaction and mulch effects were significant for all analyzed microbial parameters (P<0.001).

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

    SciTech Connect

    Gopinath, K.S.; Kennedy, D.C.

    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.

  9. 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

  10. Improved compaction of dried tannery wastewater sludge.

    PubMed

    Della Zassa, M; Zerlottin, M; Refosco, D; Santomaso, A C; Canu, P

    2015-12-01

    We quantitatively studied the advantages of improving the compaction of a powder waste by several techniques, including its pelletization. The goal is increasing the mass storage capacity in a given storage volume, and reducing the permeability of air and moisture, that may trigger exothermic spontaneous reactions in organic waste, particularly as powders. The study is based on dried sludges from a wastewater treatment, mainly from tanneries, but the indications are valid and useful for any waste in the form of powder, suitable to pelletization. Measurements of bulk density have been carried out at the industrial and laboratory scale, using different packing procedures, amenable to industrial processes. Waste as powder, pellets and their mixtures have been considered. The bulk density of waste as powder increases from 0.64 t/m(3) (simply poured) to 0.74 t/m(3) (tapped) and finally to 0.82 t/m(3) by a suitable, yet simple, packing procedure that we called dispersion filling, with a net gain of 28% in the compaction by simply modifying the collection procedure. Pelletization increases compaction by definition, but the packing of pellets is relatively coarse. Some increase in bulk density of pellets can be achieved by tapping; vibration and dispersion filling are not efficient with pellets. Mixtures of powder and pellets is the optimal packing policy. The best compaction result was achieved by controlled vibration of a 30/70 wt% mixture of powders and pellets, leading to a final bulk density of 1t/m(3), i.e. an improvement of compaction by more than 54% with respect to simply poured powders, but also larger than 35% compared to just pellets. That means increasing the mass storage capacity by a factor of 1.56. Interestingly, vibration can be the most or the least effective procedure to improve compaction of mixtures, depending on characteristics of vibration. The optimal packing (30/70 wt% powders/pellets) proved to effectively mitigate the onset of smouldering, leading to self-heating, according to standard tests, whereas the pure pelletization totally removes the self-heating hazard. PMID:26337963

  11. Backside Charging of Ccds

    NASA Astrophysics Data System (ADS)

    Iyer, Venkatraman

    1997-10-01

    Backside illuminated thinned CCDs have the highest response in the UV and blue spectral region. Their use in detectors is limited due to the instability of the CCD. A low temperature oxide nearly 30 A thick is grown on the acid thinned backside to tie up dangling bonds. The oxide carries fixed positive charges that attract and trap photogenerated electrons. A permanent and stable backside charging procedure is necessary to create a negative bias that will drive electrons to the frontside collection wells. We have shown chemisorption charging to be a novel method to permanently charge CCDs. The catalytic nature of certain metals are exploited to chemisorb oxygen as negative atomic species at the metal/oxide interface. Charging is shown to occur by depositing a thin film 10 A of platinum on the backside. No tunneling occurs because of the thick oxide. The Passivated Platinum Film (PPtF) which utilizes a hafnium oxide antireflection coating to passivate the platinum is an effective process, but it is sensitive to the environment and discharges quickly upon hydrogen exposure. A silver catalytic coating is shown to be far superior to other charging techniques. Silver irreversibly chemisorbs oxygen and hydrogen is not dissociatively adsorbed except at temperatures <100oK. High quantum efficiencies have been recorded for the UV-blue ranges. A slight drop is seen at cold temperatures due to interaction of water with oxygen to form hydroxyl ions. No change in QE is seen upon exposure to hydrogen or during outgassing. Silver is also one of the most transparent metals and easily deposited by evaporation. We therefore have developed a charging process which is nearly ideal for CCD imaging.

  12. A remark on the asymptotic form of BPS multi-dyon solutions and their conserved charges

    NASA Astrophysics Data System (ADS)

    Constantinidis, C. P.; Ferreira, L. A.; Luchini, G.

    2015-12-01

    We evaluate the gauge invariant, dynamically conserved charges, recently obtained from the integral form of the Yang-Mills equations, for the BPS multi-dyon solutions of a Yang-Mills-Higgs theory associated to any compact semi-simple gauge group G. Those charges are shown to correspond to the eigenvalues of the next-to-leading term of the asymptotic form of the Higgs field at spatial infinity, and so coinciding with the usual topological charges of those solutions. Such results show that many of the topological charges considered in the literature are in fact dynamical charges, which conservation follows from the global properties of classical Yang-Mills theories encoded into their integral dynamical equations. The conservation of those charges can not be obtained from the differential form of Yang-Mills equations.

  13. A Novel Spacecraft Charge Monitor for LEO

    NASA Technical Reports Server (NTRS)

    Goembel, Luke

    2004-01-01

    Five years ago we introduced a new method for measuring spacecraft chassis floating potential relative to the space plasma (absolute spacecraft potential) in low Earth orbit. The method, based on a straightforward interpretation of photoelectron spectra, shows promise for numerous applications, but has not yet been tried. In the interest of testing the method, and ultimately supplying another tool for measuring absolute spacecraft charge, we are producing a flight prototype Spacecraft Charge Monitor (SCM) with support from NASA's Small Business Innovation Research (SBIR) program. Although insight into the technique came from data collected in space over two decades ago, very little data are available. The data indicate that it may be possible to determine spacecraft floating potential to within 0.1 volt each with the SCM second under certain conditions. It is debatable that spacecraft floating potential has ever been measured with such accuracy. The compact, easily deployed SCM also offers the advantage of long-term stability in calibration. Accurate floating potential determinations from the SCM could be used to correct biases in space plasma measurements and evaluate charge mitigation and/or sensing devices. Although this paper focuses on the device's use in low Earth orbit (LEO), the device may also be able to measure spacecraft charge at higher altitudes, in the solar wind, and in orbits around other planets. The flight prototype SCM we are producing for delivery to NASA in the third quarter of 2004 will measure floating potential from 0 to -150 volts with 0.1 volt precision, weigh approximately 600-700 grams, consume approximately 2 watts, and will measure approximately 8 x 10 x 17 cm.

  14. Specific features of the charge neutralization of silicon carbide in sintering by electron beam in the forevacuum range of pressures

    NASA Astrophysics Data System (ADS)

    Klimov, A. S.; Burdovitsin, V. A.; Zenin, A. A.; Oks, E. M.; Khasanov, O. L.; Dvilis, E. S.; Khasanov, A. O.

    2015-08-01

    It is shown that a noticeable role in the electron beam charge neutralization in the course of electron-beam sintering of compacted silicon carbide samples is played, as the sample temperature increases, by the electrical conductivity of a sample being sintered, as well as by thermionic emission from its surface. Experimental results obtained for compacted silicon carbide are used to determine its energy gap width and the electron work function.

  15. Soil-water characteristic curves for compacted clays

    SciTech Connect

    Tinjum, J.M.; Benson, C.H.; Blotz, L.R.

    1997-11-01

    Soil-water characteristic curves (SWCCs) are presented for four compacted clay barrier soils that were prepared at different compaction water contents (dry, wet, and optimum water content) and compactive efforts (standard and modified Proctor). The SWCCs were measured in the laboratory using pressure plate extractors. The shape of the SWCC depends on compaction water content and compactive effort, but compaction water content is more important. Compaction at higher compaction water content or with greater compactive effort results in larger air entry. Also, clays with higher plasticity index have greater air-entry suction. Changes in the shape of the SWCC are consistent with changes in pore size that occur by varying compaction conditions and with the mineralogical composition of the soils. These changes in the SWCC also are reflected in the van Genuchten and Brooks-Corey parameters, which were obtained from least-squares fits to the SWCC data. Regression equations are presented that can be used to estimate the van Genuchten parameters {alpha} and n from compaction water content, compactive effort, and plasticity index.

  16. Charge Transfer Reactions

    NASA Astrophysics Data System (ADS)

    Dennerl, Konrad

    2010-12-01

    Charge transfer, or charge exchange, describes a process in which an ion takes one or more electrons from another atom. Investigations of this fundamental process have accompanied atomic physics from its very beginning, and have been extended to astrophysical scenarios already many decades ago. Yet one important aspect of this process, i.e. its high efficiency in generating X-rays, was only revealed in 1996, when comets were discovered as a new class of X-ray sources. This finding has opened up an entirely new field of X-ray studies, with great impact due to the richness of the underlying atomic physics, as the X-rays are not generated by hot electrons, but by ions picking up electrons from cold gas. While comets still represent the best astrophysical laboratory for investigating the physics of charge transfer, various studies have already spotted a variety of other astrophysical locations, within and beyond our solar system, where X-rays may be generated by this process. They range from planetary atmospheres, the heliosphere, the interstellar medium and stars to galaxies and clusters of galaxies, where charge transfer may even be observationally linked to dark matter. This review attempts to put the various aspects of the study of charge transfer reactions into a broader historical context, with special emphasis on X-ray astrophysics, where the discovery of cometary X-ray emission may have stimulated a novel look at our universe.

  17. 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 μm2/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 μm 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.

  18. RNA isolation and fractionation with compaction agents

    NASA Technical Reports Server (NTRS)

    Murphy, J. C.; Fox, G. E.; Willson, R. C.

    2001-01-01

    A new approach to the isolation of RNA from bacterial lysates employs selective precipitation by compaction agents, such as hexammine cobalt and spermidine. Using 3.5 mM hexammine cobalt, total RNA can be selectively precipitated from a cell lysate. At a concentration of 2 mM hexammine cobalt, rRNA can be fractionated from low molecular weight RNA. The resulting RNA mixture is readily resolved to pure 5S and mixed 16S/23S rRNA by nondenaturing anion-exchange chromatography. Using a second stage of precipitation at 8 mM hexammine cobalt, the low molecular weight RNA fraction can be isolated by precipitation. Compaction precipitation was also applied to the purification of an artificial stable RNA derived from Escherichia coli 5S rRNA and to the isolation of an Escherichia coli-expressed ribozyme. Copyright 2001 Academic Press.

  19. Spinning compact binary dynamics and chameleon orbits

    NASA Astrophysics Data System (ADS)

    Gergely, Lszl rpd; Keresztes, Zoltn

    2015-01-01

    We analyze 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.

  20. Compact fast analyzer of rotary cuvette type

    DOEpatents

    Thacker, Louis H.

    1976-01-01

    A compact fast analyzer of the rotary cuvette type is provided for simultaneously determining concentrations in a multiplicity of discrete samples using either absorbance or fluorescence measurement techniques. A rigid, generally rectangular frame defines optical passageways for the absorbance and fluorescence measurement systems. The frame also serves as a mounting structure for various optical components as well as for the cuvette rotor mount and drive system. A single light source and photodetector are used in making both absorbance and fluorescence measurements. Rotor removal and insertion are facilitated by a swing-out drive motor and rotor mount. BACKGROUND OF THE INVENTION The invention relates generally to concentration measuring instruments and more specifically to a compact fast analyzer of the rotary cuvette type which is suitable for making either absorbance or fluorescence measurements. It was made in the course of, or under, a contract with the U.S. Atomic Energy Commission.

  1. Compaction of granular material inside confined geometries

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    In both nature and the laboratory, 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.

  2. Compact stereo endoscopic camera using microprism arrays.

    PubMed

    Yang, Sung-Pyo; Kim, Jae-Jun; Jang, Kyung-Won; Song, Weon-Kook; Jeong, Ki-Hun

    2016-03-15

    This work reports a microprism array (MPA) based compact stereo endoscopic camera with a single image sensor. The MPAs were monolithically fabricated by using two-step photolithography and geometry-guided resist reflow to form an appropriate prism angle for stereo image pair formation. The fabricated MPAs were transferred onto a glass substrate with a UV curable resin replica by using polydimethylsiloxane (PDMS) replica molding and then successfully integrated in front of a single camera module. The stereo endoscopic camera with MPA splits an image into two stereo images and successfully demonstrates the binocular disparities between the stereo image pairs for objects with different distances. This stereo endoscopic camera can serve as a compact and 3D imaging platform for medical, industrial, or military uses. PMID:26977690

  3. The Atacama Compact Array: An Overview

    NASA Astrophysics Data System (ADS)

    Iguchi, S.; Wilson, T. L.

    2010-01-01

    When completed, ALMA will comprise a 12-meter diameter antennas array (12-m Array) of a minimum of fifty antennas, and the ACA (Atacama Compact Array), composed of four 12-meter diameter antennas and twelve 7-meter diameter antennas. Out of the fifty antennas of the 12-m Array, one-half are provided by the North American partners of ALMA, the other half by the European partners. The sixteen antennas that will comprise the ACA are provided by the East Asian Partners of ALMA. In the last issue of the ALMA Science Newsletter, we outlined the testing of the prototype ALMA 12-meter diameter antennas and the procurement process for these antennas. In that article, only a short account was given of the antennas for the Atacama Compact Array (ACA). In the following we give an overview of the ACA, starting with an introduction to imaging using interferometers.

  4. Compact fluorescence spectroscopic tool for cancer detection

    NASA Astrophysics Data System (ADS)

    Nadeau, Valerie; Hamdan, Khaled; Hewett, Jacqueline; Makaryceva, Juljia; Tait, Iain; Cuschieri, Alfred; Padgett, Miles J.

    2002-05-01

    We describe a compact fluorescence spectroscopic tool for in vivo point monitoring of aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence and autofluorescence, as a non-invasive method of differentiating normal and cancerous tissue. This instrument incorporates a 405nm diode laser with a shutter to prevent exposure of tissue to harmful light doses and reduce photobleaching, a bifurcated optical fibre to allow illumination of tissue and collection of fluorescence with a single fibre, a compact grating spectrometer for collection of spectra and a PC for system control. We present spectra obtained using this system both during routine gastro-intestinal (GI) endoscopy for cancer detection and during photodynamic therapy (PDT) of anal intraepithelial neoplasia (AIN) for monitoring of treatment progress. These results illustrate the potential of the system to be used for fluorescence monitoring in a variety of clinical applications.

  5. Human gait recognition based on compactness

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Jiang, Jie; Zhang, Guangjun

    2008-10-01

    Gait recognition is new biological identity technology and widely researched in recent years for its many advantages compared with other biological identity technology. In this paper, we propose a simple but effective feature-compactness for gait recognition. First an improved background subtraction algorithm is used to obtain the silhouettes. Then the compactness is extracted from the images in the gait sequence as the feature vector. In the step of classification, DTW algorithm is adopted to adjust the feature vectors before classifying and two classifiers (NN and ENN) are used as classifiers. Because of the simple features which we choose, it consumes little time for recognition and the results turn out to be encouraging.

  6. Compact ranges in antenna and RCS measurements

    NASA Astrophysics Data System (ADS)

    Audone, B.

    1989-09-01

    With the increased complexity and extended frequency range of operation model measurements and far field test ranges are no longer suitable to satisfy the demand of accurate testing. Moreover plane wave test conditions are required for Radar Cross Section (RCS) measurements which represent a key point in stealth technology. Compact ranges represent the best test facilities available presently since they allow for indoor measurements under far field conditions in real time without any calculation effort. Several types of compact ranges are described and compared discussing their relevant advantages with regard to RCS and antenna measurements. In parallel to measuring systems sophisticated computer models were developed with such a high level of accuracy that it is questionable whether experiments give better results than theory. Tests performed on simple structures show the correlation between experimental results and theoretical ones derived on the basis of GTD computer codes.

  7. 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

  8. Compact dusty clouds in a cosmic environment

    SciTech Connect

    Tsytovich, V. N.; Ivlev, A. V.; Burkert, A.; Morfill, G. E.

    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.

  9. Compact coverings for Baire locally convex spaces

    NASA Astrophysics Data System (ADS)

    Ka[Combining Cedilla]Kol, J.; Lopez Pellicer, M.

    2007-08-01

    Very recently Tkachuk has proved that for a completely regular Hausdorff space X the space Cp(X) of continuous real-valued functions on X with the pointwise topology is metrizable, complete and separable iff Cp(X) is Baire (i.e. of the second Baire category) and is covered by a family of compact sets such that K[alpha][subset of]K[beta] if [alpha][less-than-or-equals, slant][beta]. Our general result, which extends some results of De Wilde, Sunyach and Valdivia, states that a locally convex space E is separable metrizable and complete iff E is Baire and is covered by an ordered family of relatively countably compact sets. Consequently every Baire locally convex space which is quasi-Suslin is separable metrizable and complete.

  10. Compact snapshot birefringent imaging Fourier transform spectrometer

    NASA Astrophysics Data System (ADS)

    Kudenov, Michael W.; Dereniak, Eustace L.

    2010-08-01

    The design and implementation of a compact multiple-image Fourier transform spectrometer (FTS) is presented. Based on the multiple-image FTS originally developed by A. Hirai, the presented device offers significant advantages over his original implementation. Namely, its birefringent nature results in a common-path interferometer which makes the spectrometer insensitive to vibration. Furthermore, it enables the potential of making the instrument ultra-compact, thereby improving the portability of the sensor. The theory of the birefringent FTS is provided, followed by details of its specific embodiment. A laboratory proof of concept of the sensor, designed and developed at the Optical Detection Lab, is also presented. Spectral measurements of laboratory sources are provided, including measurements of light-emitting diodes and gas-discharge lamps. These spectra are verified against a calibrated Ocean Optics USB2000 spectrometer. Other data were collected outdoors, demonstrating the sensor's ability to resolve spectral signatures in standard outdoor lighting and environmental conditions.

  11. Elve doublets and compact intracloud discharges

    NASA Astrophysics Data System (ADS)

    Marshall, R. A.; Silva, C. L.; Pasko, V. P.

    2015-07-01

    We present evidence of ionospheric optical signatures of lightning, known as elves, which sometimes occur in pairs separated in time by ˜80-160 μs. We demonstrate that these "elve doublets" are the ionospheric signature of compact intracloud discharges (CIDs), which are extremely powerful, compact discharges that are thought to occur near the tops of thunderclouds. In this paper, using simple geometric calculations and full electromagnetic simulations, we show that CIDs from altitudes 14-22 km explain the time delay observed in elve doublets, consistent with typical CID altitudes. Furthermore, we show that the relative brightness of the first and second elves in the doublet is likely related to the orientation of the CID, and angles of 5°- 20° with respect to the vertical are consistent with the observed brightness ratios.

  12. Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

    NASA Astrophysics Data System (ADS)

    Guise, Nicholas D.; Brewer, Samuel M.; Tan, Joseph N.

    A newly constructed apparatus at the United States National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning trap along with a fast time-of-flight MCP detector capable of resolving the charge-state evolution of trapped ions. Holes in the two-magnet Penning trap ring electrode allow for optical and atomic beam access. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, astrophysics, and plasma diagnostics.

  13. Multifunctional graded index TiO2 compact layer for performance enhancement in dye sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Abdullah, M. H.; Rusop, M.

    2013-11-01

    A specially tailored index TiO2 compact layer (arc-TiO2) has been successfully deposited to serve as photoanode of a dye-sensitized solar cell (DSSC) by radio-frequency magnetron sputtering. The employment of the TiO2 compact layer in the DSSC was systematically investigated by means of UV-absorption spectra, incident photon to current efficiency (IPCE), open-circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS). The higher and red-shifted transmittance spectra of the ITO/arc-TiO2 electrode mimic the IPCE spectra of the DSSC, in a specific wavelength region. Furthermore, the blue-shift of the UV-absorption spectra and lower R1 value obtained from EIS measurements implied the decrease of the charge interfacial resistance, and this consequently facilitates the charge transport from the nanocrystalline-TiO2 to the ITO. The integrated effects of the arc-TiO2 compact layer originate the remarkable improvement in this type of DSSC applications. As a result, the arc-TiO2-based DSSC showed higher conversion efficiency of about 4.38%, representing almost 53% increment compared to bare ITO cell. This work also discuss the fundamental insight of the compact layer that determines the origin of such improvement in the DSSC performance.

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

    PubMed

    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. PMID:21034115

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

    SciTech Connect

    Nunomura, Shota; Kondo, Michio; Shiratani, Masaharu; Koga, Kazunori; Watanabe, Yukio

    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.

  16. A newly discovered compact planetary nebula

    NASA Astrophysics Data System (ADS)

    Cappellaro, E.; Turatto, M.; Sabbadin, F.

    1989-07-01

    An H-alpha emission object is identified in a 103a-E + RG1 objective prism plate taken with the 92/67-cm Schmidt telescope of the Astronomical Observatory of Padua at Asiago (Italy). The object turns out to be a compact planetary nebula located at alpha(1950.0) = 18 h 4.3 min and delta(1950.0) = -8 deg 56.4 arcmin (classification code: 19 + 5 deg 1).

  17. Compact Ion Source for Mass Spectrometers

    NASA Technical Reports Server (NTRS)

    Anicich, V. G.; Huntress, W. T. J.

    1982-01-01

    Cyclotron-resonance device uses miniature components and permanent magnet for small size, low weight, and low cost. Gas molecules are ionized by electrons from hot filament. Magnetic field, acting with electrostatic drift field, causes ions to move in circles with a superimposed drift perpendicular to both fields, toward the exit. Compact source can be used for studying ion-molecule reactions by ion cyclotron-resonance methods in conventional mass spectrometer with either magnetic sector or quadrupole sector.

  18. Compact stars in Kaluza -Klein World

    NASA Astrophysics Data System (ADS)

    Gábor Barnaföldi, Gergely; Lévai, Péter; Lukács, Béla

    2010-03-01

    Unification and geometrization of interactions has been extensively studied during the XX. century. In this short contribution we investigated the possible effect of an extra compactified dimension (alias hypercharge) on a flavor dependent gravitational potential, proposed by Fischbach et al.. We estimated the deviation from the 3 + 1 dimensional scheme and found that, although the deviation is moderate, for celestial compact object it may be higher by orders of magnitude than in terrestrial laboratory measurements.

  19. Compact 2-D graphical representation of DNA

    NASA Astrophysics Data System (ADS)

    Randić, Milan; Vračko, Marjan; Zupan, Jure; Novič, Marjana

    2003-05-01

    We present a novel 2-D graphical representation for DNA sequences which has an important advantage over the existing graphical representations of DNA in being very compact. It is based on: (1) use of binary labels for the four nucleic acid bases, and (2) use of the 'worm' curve as template on which binary codes are placed. The approach is illustrated on DNA sequences of the first exon of human β-globin and gorilla β-globin.

  20. Compact quiescent galaxies at intermediate redshifts {sup ,}

    SciTech Connect

    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.