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1

Polytropic spheres with electric charge: Compact stars, the Oppenheimer-Volkoff and Buchdahl limits, and quasiblack holes  

NASA Astrophysics Data System (ADS)

We explore a class of compact charged spheres made of a charged perfect fluid with a polytropic equation of state. The charge density is chosen to be proportional to the energy density. The study is performed by solving the Tolman-Oppenheimer-Volkoff equation, which describes the hydrostatic equilibrium. We show the dependence of the structure of the spheres for several characteristic values of the polytropic exponent and for different values of the charge densities. We also study other physical properties of the charged spheres, such as the total mass, total charge, radius and sound speed and their dependence on the polytropic exponent. We find that for the polytropic exponent ?=4/3 the Chandrasekhar mass limit coincides with the Oppenheimer-Volkoff mass limit. We test the Oppenheimer-Volkoff limit for such compact objects. We also analyze the Buchdahl limit for these charged polytropic spheres, which happens in the limit of very high polytropic exponents, i.e., for a stiff equation of state. It is found that this limit is extremal and it is a quasiblack hole.

Arbañil, José D. V.; Lemos, José P. S.; Zanchin, Vilson T.

2013-10-01

2

Gravito-electrostatic fluctuations of a polytropic charged dust cloud  

NASA Astrophysics Data System (ADS)

An analytical model to explore the weakly nonlinear gravito-electrostatic waves in a field-free polytropic dust molecular cloud on the astrophysical scales of space and time is proposed. The polytrope consists of the lighter electrons, ions and massive dust grains with full ionization. This is a nonthermalized situation due to the cold grains, and the mutually thermalized hot electrons and hot ions. A quasi-hydrostatic equilibrium in one-dimensional (1D, Cartesian) configuration is adopted with presumed global quasi-neutrality. The grain dynamics considered is such that exact gravito-electrostatic equilibrium is facilitated with their first-order perturbed self-gravitational potential. The analytical infrastructure is developed by a standard multi-scale analysis of stretched variables centered on the assumed initially ‘homogeneous’ equilibrium in accordance with the Jeans swindle. We derive a new gravito-electrostatically coupled pair of modified Korteweg–de Vries (m-KdV) equations having unique self-consistent nonlinear sources arising due to gravito-electrostatic intermixed coupling. A detailed numerical shape analysis of the fluctuations is carried out in order to see their parametric excitations as solitary spectral patterns. Interestingly, it is seen that the electrostatic fluctuations undergo bi-periodicity, while the self-gravitational counterparts retain uni-periodicity in phase space. Nontrivial aspects of the results relevant in space and astrophysical environments are summarily indicated.

Gohain, M.; Karmakar, P. K.

2014-12-01

3

Polytropic process and tropical Cyclones  

E-print Network

We show a parallelism between the expansion and compression of the atmosphere in the secondary cycle of a tropical cyclone with the fast expansion and compression of wet air in a bottle. We present a simple model in order to understand how the system (cyclone) draws energy from the air humidity. In particular we suggest that the upward (downward) expansion (compression) of the warm (cold) moist (dry) air follows a polytropic process, $PV^\\beta$= constant. We show both experimentally and analytically that $\\beta$ depends on the initial vapor pressure in the air. We propose that the adiabatic stages in the Carnot-cycle model for the tropical cyclone be replaced by two polytropic stages. These polytropic processes can explain how the wind wins energy and how the rain and the dry bands are produced inside the storm.

Romanelli, Alejandro; Rodríguez, Juan

2013-01-01

4

Stability analysis of Newtonian polytropes  

E-print Network

We analyze the stability of Newtonian polytropic static fluid spheres, described by the Lane-Emden equation. In the general case of arbitrary polytropic indices the Lane-Emden equation is a non-linear second order ordinary differential equation. By introducing a set of new variables, the Lane-Emden equation can be reduced to an autonomous system of two ordinary differential equations, which in turn may be transformed to another regular second order differential equation. We perform the study of stability by using linear stability analysis, the Jacobi stability analysis (Kosambi-Cartan-Chern theory) and the Lyapunov function method. Depending on the values of the polytropic index characterizing the fluid, these different methods yield different qualitative results on the stability of the solutions. On the other hand, these techniques offer a powerful method for constraining the physical properties of the Newtonian stars.

Boehmer, Christian G

2009-01-01

5

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

E-print Network

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

Wilt, Brian A

2007-01-01

6

The structure of tidally distorted polytropes  

NASA Astrophysics Data System (ADS)

The structural parameters of tidally distorted polytropes (Chandrasekhar, 1933) are calculated numerically, employing the method developed by Monaghan and Roxburgh (1965) for rotating polytropes. The results for index (n) values 1.5, 2.0, and 3.0 are presented in tables and compared to those for the Roche problem.

Singh, M.; Singh, G.

1984-03-01

7

Conformally flat polytropes for anisotropic matter  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

8

Compact Charge Model for Independent-Gate Asymmetric DGFET  

Microsoft Academic Search

Analytical expressions for terminal charges of an independent-gate asymmetric double gate MOSFET (DGFET) are derived. The new charge model is C? continuous, valid for all bias conditions and does not involve charge-sheet approximation. This is accomplished by developing the symmetric linearization method in the form that does not require identical boundary conditions at the two Si-SiO2 interfaces and allows for

Gajanan Dessai; Weimin Wu; Gennady Gildenblat

2010-01-01

9

New Compact CMOS Li-Ion Battery Charger Using Charge-Pump Technique for Portable Applications  

Microsoft Academic Search

This paper presents a new compact CMOS Li-Ion battery charger for portable applications that uses a charge-pump technique. The proposed charger features a small chip size and a simple circuit structure. Additionally, it provides basic functions with voltage\\/current detection, end-of-charge detection, and charging speed control. The charger operates in dual-mode and is supported in the trickle\\/large constant-current mode to constant-voltage

Yuh-Shyan Hwang; Shu-Chen Wang; Fong-Cheng Yang; Jiann-Jong Chen

2007-01-01

10

Low power, compact charge coupled device signal processing system  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

11

Magnetic flux concentrations in a polytropic atmosphere  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

12

Universal charge-radius relation for subatomic and astrophysical compact objects.  

PubMed

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 4 x 10(2) and 10(4) fm the upper bound on the net charge is given by the universal relation Z=0.71R(fm), and for larger radii (measured in femtometers or kilometers) Z=7 x 10(-5)R_(2)(fm)=7 x 10(31)R_(2)(km). For objects with nuclear density the relation corresponds to Z approximately 0.7A(1/3)( (10(8)10(12)), where A is the baryon number. For some systems this universal upper bound improves existing charge limits in the literature. PMID:18518093

Madsen, Jes

2008-04-18

13

Binary fission in damped rotating polytropes. II  

Microsoft Academic Search

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

R. A. Gingold; J. J. Monaghan

1979-01-01

14

Double-polytropic closure in the magentosheath  

NASA Technical Reports Server (NTRS)

The magnetosheath plasma is usually neither isotropic nor adiabatic. This paper contains an attempt to decribe its thermodynamic properties in terms of two polytropic laws, p(sub perpendicular)/rho B(exp gamma(sub perpendicular)-1) = C(sub perpendicular) and p(sub parallel)B(exp gamma(sub parallel)-1)/rho(exp gamma(sub parallel)) = C(sub parallel), such that for gamma(sub perpendicular) = 2, gamma(sub parallel) = 3 the usual Chew-Goldberger-Low double-adiabatic expressions are recovered and for gamma(sub perpendicular) = 1, gamma(sub parallel) = 1 double-isothermal conditions are obtained. Using data from the AMPTE/IRM spacecraft, we show that the subsolar magnetosheath plasma may be better described by the double-polytropic laws than by the mirror instability threshold, in particular in the low beta region near the magnetopause. The inferred polytropic exponents vary from event to event but are typically in the ranges of gamma(sub perpendicular) = 0.94 +/- 0.10 and gamma(sub parallel) = 1.14 +/- 0.13 for the 29 cases we have examined.

Hau, L.-N.; Phan, T.-D.; Sonnerup, B. U. O.; Paschmann, G.

1993-01-01

15

Polytropic bulk viscous cosmological model with variable G and ?  

E-print Network

We consider a Bianchi type-I Polytropic bulk viscous fluid cosmological model with variable G and {\\Lambda}. To get a deterministic model, we assume some conditions of A, B, C, and polytropic relation to find the results. physical significance of the cosmological models have also been discussed.

Rishi Kumar Tiwari; Mukesh Sharma; Sonia Sharma

2014-02-20

16

Charge based DC compact modeling of bulk FinFET transistor  

NASA Astrophysics Data System (ADS)

Multiple-gate MOSFETs became an industrial reality in the last years. Due to a pragmatic trade-off between CMOS process baselines compatibility, improved performance compared to planar bulk architecture, and cost, bulk FinFETs emerged as the technological solution to provide downscaling for the 14/22 nm technological nodes. In this work, a charge based DC compact model based on the SDDG Model is demonstrated for this new generation of FinFET transistors and describes continuously the transistor characteristics in all operating regions. Validating the model against two bulk FinFET baselines (NMOS, PMOS, various gate lengths and EOT), an excellent agreement is found for transfer and output characteristics (linear and saturation regimes), transconductance/output conductance, and gm/IDS characteristics. Temperature dependence is also taken into account and validated (T range from 25 °C up to 175 °C).

Cerdeira, A.; Garduño, I.; Tinoco, J.; Ritzenthaler, R.; Franco, J.; Togo, M.; Chiarella, T.; Claeys, C.

2013-09-01

17

Polytropic models of filamentary interstellar clouds - I. Structure and stability  

NASA Astrophysics Data System (ADS)

The properties of filamentary interstellar clouds observed at submillimetre wavelengths, especially by the Herschel Space Observatory, are analysed with polytropic models in cylindrical symmetry. The observed radial density profiles are well reproduced by negative-index cylindrical polytropes with polytropic exponent 1/3 ? ?p ? 2/3 (polytropic index -3 ? n ? -3/2), indicating either external heating or non-thermal pressure components. However, the former possibility requires unrealistically high gas temperatures at the filament's surface and is therefore very unlikely. Non-thermal support, perhaps resulting from a superposition of small-amplitude Alfvén waves (corresponding to ?p = 1/2), is a more realistic possibility, at least for the most massive filaments. If the velocity dispersion scales as the square root of the density (or column density) on the filament's axis, as suggested by observations, then polytropic models are characterized by a uniform width. The mass per unit length of pressure-bounded cylindrical polytropes depends on the conditions at the boundary and is not limited as in the isothermal case. However, polytropic filaments can remain stable to radial collapse for values of the axis-to-surface density contrast as large as the values observed only if they are supported by a non-isentropic pressure component.

Toci, Claudia; Galli, Daniele

2015-01-01

18

The structure of rotating polytropes (Second order)  

NASA Astrophysics Data System (ADS)

The structural equations for the inner and outer regions of a rotating polytrope (as used in stellar-structure models) are reformulated to include second-order terms in the perturbation parameter alpha and solved by extending the method of Monaghan and Roxburgh (1965), as used in the first order by Singh and Singh (1982). A critical configuration at which the centrifugal force balances gravity at the equator is defined, and numerical results for parameter values of interest in astrophysics are presented in tables. Comparison of the results for alpha, xi(e), and xi(p) with those of James (1964) and Singh and Singh (1982) shows that the improvement introduced by the use of the second-order method is small, and continued modeling based on the first-order values is recommended.

Singh, G. R.; Singh, M.

1984-11-01

19

Rapidly rotating polytropes in general relativity  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

20

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

21

The structure of the tidally and rotationally distorted polytropes  

NASA Astrophysics Data System (ADS)

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.

Singh, M.; Singh, G.

1983-10-01

22

Is scalar-tensor gravity consistent with polytropic stellar models?  

E-print Network

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

Kaisa Henttunen; Iiro Vilja

2014-08-26

23

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

NASA Astrophysics Data System (ADS)

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 K19+ were reached after about a 3 s breeding time. The capture and breeding efficiencies up to 0.016(4)% for K17+ have been measured.

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

2012-05-01

24

Symmetry Reduction of Lane-Emden Equation for Polytropes  

E-print Network

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

Babur M. Mirza

2008-07-03

25

Polytropic models of filamentary interstellar clouds - II. Helical magnetic fields  

NASA Astrophysics Data System (ADS)

We study the properties of magnetized cylindrical polytropes as models for interstellar filamentary clouds, extending the analysis presented in a companion paper. We formulate the general problem of magnetostatic equilibrium in the presence of a helical magnetic field, with the aim of determining the degree of support or compression resulting from the magnetization of the cloud. We derive scale-free solutions appropriate to describe the properties of the envelopes of filaments at radii larger than the flat-density region. In these solutions, the polytropic exponent determines the radial profiles of the density and the magnetic field. The latter decreases with radius less steeply than the density, and field lines are helices twisted over cylindrical surfaces. A soft equation of state supports magnetic configurations that preferentially compress and confine the filament, whereas in the isothermal limit the field provides support. For each value of the polytropic exponent, the Lorentz force is directed outwards or inwards depending on whether the pitch angle is below or above some critical value which is a function of the polytropic exponent only.

Toci, Claudia; Galli, Daniele

2015-01-01

26

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

E-print Network

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 the non-linear electrodynamics affects the geodesic deviation and the redshift of photons propagating near this massive charged object and, in the linear approximation, the effects of electromagnetic self-interaction can be disparted from the usual Reissner-Nordstr\\"om terms. In the particular case of Euler-Heisenberg effective Lagrangian, we find that these self-interaction effects might be important near charged white dwarfs.

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

2015-01-26

27

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

E-print Network

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 the non-linear electrodynamics affects the geodesic deviation and the redshift of photons propagating near this massive charged object and, in the linear approximation, the effects of electromagnetic self-interaction can be disparted from the usual Reissner-Nordstr\\"om terms. In the particular case of Euler-Heisenberg effective Lagrangian, we find that these self-interaction effects might be important near charged white dwarfs.

Cuzinatto, R R; de Vasconcelos, K C; Medeiros, L G; Pompeia, P J

2015-01-01

28

Near-polytropic stellar simulations with a radiative surface  

NASA Astrophysics Data System (ADS)

Context. Studies of solar and stellar convection often employ simple polytropic setups using the diffusion approximation instead of solving the proper radiative transfer equation. This allows one to control separately the polytropic index of the hydrostatic reference solution, the temperature contrast between top and bottom, and the Rayleigh and Péclet numbers. Aims: Here we extend such studies by including radiative transfer in the gray approximation using a Kramers-like opacity with freely adjustable coefficients. We study the properties of such models and compare them with results from the diffusion approximation. Methods: We use the Pencil code, which is a high-order finite difference code where radiation is treated using the method of long characteristics. The source function is given by the Planck function. The opacity is written as ? = ?0?aTb, where a = 1 in most cases, b is varied from -3.5 to + 5, and ?0 is varied by four orders of magnitude. We adopt a perfect monatomic gas. We consider sets of one-dimensional models and perform a comparison with the diffusion approximation in one- and two-dimensional models. Results: Except for the case where b = 5, we find one-dimensional hydrostatic equilibria with a nearly polytropic stratification and a polytropic index close to n = (3 - b)/(1 + a), covering both convectively stable (n> 3/2) and unstable (n< 3/2) cases. For b = 3 and a = -1, the value of n is undefined a priori and the actual value of n depends then on the depth of the domain. For large values of ?0, the thermal adjustment time becomes long, the Péclet and Rayleigh numbers become large, and the temperature contrast increases and is thus no longer an independent input parameter, unless the Stefan-Boltzmann constant is considered adjustable. Conclusions: Proper radiative transfer with Kramers-like opacities provides a useful tool for studying stratified layers with a radiative surface in ways that are more physical than what is possible with polytropic models using the diffusion approximation. Appendices are available in electronic form at http://www.aanda.org

Barekat, A.; Brandenburg, A.

2014-11-01

29

An ultra compact 10 GHz electron-cyclotron-resonance ion source (ECRIS) for the production of multiply charged ions  

SciTech Connect

There is a growing interest in the use of beams of multiply charged ions produced in special environments like high voltage platforms, Dynamitrons, Van-de-Graaff accelerators or on-line production systems for radioactive beam facilities. A compact 10 GHz ECR ion source (200 mm long, 170 mm diameter) has been developed and tested. The complete magnetic structure made from permanent magnet material is comprised of four ring magnets producing an asymmetric axial magnetic field with a mirror ratio of 2.5 and a 24 piece hexapole magnet with a maximum radial field of 0.94T inside the plasma chamber of 25 mm inner diameter. The coupling of the microwave to the plasma using a resonant transition line from rectangular to circular waveguide shows efficient ECR plasma heating at microwave power levels around 10 watts. Charge state distributions for various elements with intensities up to 320e{mu}A and their dependence on operation parameters will be presented as well as VUV spectra in the wavelength region down to 15 nm. {copyright} {ital 1997 American Institute of Physics.}

Schlapp, M. [Argonne National Laboratory, Physics Division, Illinois (United States); Trassl, R.; Hathiramani, P. [Institut fuer Kernphysik, Strahlenzentrum, Justus-Liebig-Universitaet Giessen (Germany); McCullough, R.W.; Greenwood, J.B. [Department of Pure and Applied Physics, The Queens University of Belfast, Belfast (United Kingdom); Salzborn, E. [Institut fuer Kernphysik, Strahlenzentrum, Justus-Liebig-Univeristaet Giessen (Germany)

1997-02-01

30

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

SciTech Connect

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

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

2012-02-15

31

Self-similar dynamics of polytropic gaseous spheres  

NASA Technical Reports Server (NTRS)

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.

Suto, Yasushi; Silk, Joseph

1988-01-01

32

1784 IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. ED-31, NO. 12, DECEMBER 1984 A Linear and Compact Charge-Coupled Charge  

E-print Network

Charge-Coupled Charge Packet Differencer/Replicator ERIC R. FOSSUM, MEMBER. IEEE, AND RICHARD CLARK BARKER, FELLOW, IEEE Abstract-A new charge-coupled circuit for creating a charge packet equal to the difference of two input charge packets is analyzed. The circuit features inherent linearity through the use

Fossum, Eric R.

33

Long-Term Variability of the Polytropic Index of Solar Wind Protons at 1 AU  

NASA Astrophysics Data System (ADS)

Spacecraft data from the OMNI database were used to calculate the value of the polytropic index of the solar wind by fitting the logarithms of proton density and temperature in selected time intervals from 1 January 1995 to 30 June 2012. Bernoulli's integral and the correlation coefficient were used to filter the results. An alternative method based on the maximization of the correlation coefficient was employed to confirm our results. The long-term behavior of the polytropic index we obtained is found to be virtually identical for both methods. We noticed a characteristic behavior of the estimated polytropic index values, particularly from 1995 to 2006, which tends to have a periodicity of about one year. The distribution of the polytropic index is best described by a ?-Gaussian distribution with mean ? 1.8 and standard deviation ? 2.4. We finally examined the possible correlation between the polytropic index values and solar activity.

Nicolaou, G.; Livadiotis, G.; Moussas, X.

2014-04-01

34

Critical rotation of general-relativistic polytropic models revisited  

NASA Astrophysics Data System (ADS)

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.

Geroyannis, V.; Karageorgopoulos, V.

2013-09-01

35

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

SciTech Connect

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.

Furman, M.A.

2007-05-29

36

Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method  

NASA Astrophysics Data System (ADS)

The objective of this study is to investigate a high performance and lower cost compact gamma camera module for a multi-head small animal SPECT system. A compact camera module was developed using a thin Lutetium Oxyorthosilicate (LSO) scintillation crystal slice coupled to a Hamamatsu H8500 position sensitive photomultiplier tube (PSPMT). A two-stage charge division readout board based on a novel sub-tractive resistive readout with a truncated center-of-gravity (TCOG) positioning method was developed for the camera. The performance of the camera was evaluated using a flood 99mTc source with a four-quadrant bar-mask phantom. The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor. The response output area (ROA) of the camera shown in the flood image was improved up to 34%, and an intrinsic spatial resolution better than 2 mm of detector was achieved. In conclusion, the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.

Dai, Qiu-Sheng; Zhao, Cui-Lan; Zhang, Hua-Lin; Qi, Yu-Jin

2010-08-01

37

A compact tetrathiafulvalene-benzothiadiazole dyad and its highly symmetrical charge-transfer salt: ordered donor ?-stacks closely bound to their acceptors.  

PubMed

A compact and planar donor-acceptor molecule 1 comprising tetrathiafulvalene (TTF) and benzothiadiazole (BTD) units has been synthesised and experimentally characterised by structural, optical, and electrochemical methods. Solution-processed and thermally evaporated thin films of 1 have also been explored as active materials in organic field-effect transistors (OFETs). For these devices, hole field-effect mobilities of ?FE = (1.3±0.5)×10(-3) and (2.7±0.4)×10(-3) ?cm(2) ?V?s(-1) were determined for the solution-processed and thermally evaporated thin films, respectively. An intense intramolecular charge-transfer (ICT) transition at around 495?nm dominates the optical absorption spectrum of the neutral dyad, which also shows a weak emission from its ICT state. The iodine-induced oxidation of 1 leads to a partially oxidised crystalline charge-transfer (CT) salt {(1)2I3}, and eventually also to a fully oxidised compound {1I3}?1/2I2. Single crystals of the former CT compound, exhibiting a highly symmetrical crystal structure, reveal a fairly good room temperature electrical conductivity of the order of 2?S?cm(-1). The one-dimensional spin system bears compactly bonded BTD acceptors (spatial localisation of the LUMO) along its ridge. PMID:24737663

Geng, Yan; Pfattner, Raphael; Campos, Antonio; Hauser, Jürg; Laukhin, Vladimir; Puigdollers, Joaquim; Veciana, Jaume; Mas-Torrent, Marta; Rovira, Concepció; Decurtins, Silvio; Liu, Shi-Xia

2014-06-01

38

On the Design of a Low Power Compact Spiking Neuron Cell Based on Charge-Coupled Synapses  

Microsoft Academic Search

A charge-coupled silicon synapse with a floating diffusion output is proposed as the basis for a new electronic, spiking neuron cell. The synapse is formed by a two-stage charge transfer device with the weight function stored in a floating gate over the first stage. The output of the synapses feeds into the multi-gate inputs of a MOSFET which themselves capacitively

Yajie Chen; Steve Hall; Liam Mcdaid; Octavian Buiu; Peter Kelly

2006-01-01

39

Compact accelerator  

DOEpatents

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).

Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Kirbie, Hugh C. (Los Alamos, NM)

2007-02-06

40

Self-similar shocks in polytropic gas flows around star-forming regions  

NASA Astrophysics Data System (ADS)

Self-similar shock solutions in spherically symmetric polytropic gas flows are constructed and analysed in contexts of protostar formation processes. Among other possible solutions, we model a similarity shock across the sonic critical curve with an inner free-fall core collapse and a simultaneous outer expansion of the extended envelope; the separation or stagnation surface between these two flow zones travels outwards in a self-similar manner at a variable speed. One readily obtains accretion shock solutions. Semicomplete self-similar solutions across the sonic critical curve either once or twice without shocks can also be constructed. Features of star formation clouds of our polytropic model include the mass density scaling in the outer flow zone ? ~ r-2/(2-?), the temperature scalings of the inner flow zone T ~ r-3(?-1)/2 and of the outer flow zone T ~ r-2(?-1)/(2-?) and the variable central mass accretion rate , where ? is the polytropic index, k is a constant, m0 is the core mass and G is the gravitational constant. Spectral line profiles characteristic of the `envelope expansion with core collapse' shock solutions are expected. Random magnetic field permeated in a partially ionized cloud can be incorporated into this theoretical polytropic model framework. We discuss briefly our results in context of the oft-observed starless B335 cloud system as an example.

Lou, Yu-Qing; Gao, Yang

2006-12-01

41

Models of universe with a polytropic equation of state: I. The early universe  

NASA Astrophysics Data System (ADS)

We construct models of universe with a generalized equation of state having a linear component and a polytropic component. Concerning the linear equation of state , we assume . This equation of state describes radiation ( or pressureless matter (. Concerning the polytropic equation of state , we remain very general allowing the polytropic constant k and the polytropic index n to have arbitrary values. In this paper, we consider positive indices n > 0 . In that case, the polytropic component dominates the linear component in the early universe where the density is high. For , n = 1 and , where g/m3 is the Planck density, we obtain a model of early universe describing the transition from the vacuum energy era to the radiation era. The universe exists at any time in the past and there is no primordial singularity. However, for t < 0 , its size is less than the Planck length m. In this model, the universe undergoes an inflationary expansion with the Planck density g/m3 (vacuum energy) that brings it from the Planck size m at t = 0 to a size m at s (corresponding to about 23.3 Planck times s). For , n = 1 and , we obtain a model of early universe with a new form of primordial singularity: The universe starts at t = 0 with an infinite density and a finite radius a = a 1 . Actually, this universe becomes physical at a time s from which the velocity of sound is less than the speed of light. When , the universe enters in the radiation era and evolves like in the standard model. We describe the transition from the vacuum energy era to the radiation era by analogy with a second-order phase transition where the Planck constant ? plays the role of finite-size effects (the standard Big Bang theory is recovered for ? = 0.

Chavanis, Pierre-Henri

2014-02-01

42

Pair production of heavy MSSM charged and neutral Higgs bosons in multi-TeV e{sup +}e{sup -} collisions at the Compact Linear Collider  

SciTech Connect

In the theoretical framework of the minimal supersymmetric extension of the standard model (MSSM), we study the pair production of heavy charged and neutral Higgs bosons in e{sup +}e{sup -} collisions with a center-of-mass energy of 3 TeV, at the Compact Linear Collider (CLIC). The high-energy beam-beam effects at the interaction point are taken into account in our simulations. With an integrated luminosity of 3000 fb{sup -1}, the hadronic cascade decays of H{sup +}H{sup -} and A{sup 0}H{sup 0} pairs can be observed over a wide range of Higgs boson masses, extending beyond 1 TeV. The Higgs mass parameter m{sub A} can be derived from a {chi}{sup 2}-analysis, and the corresponding statistical error was found to be smaller than 1%. In addition, by comparing the signal rates of different decay channels, one can determine the ratio between the vacuum expectation values tan{beta} with a good accuracy in the intermediate region, i.e. when tan{beta} lies between 6 and 11 typically.

Coniavitis, Elias; Ferrari, Arnaud [Uppsala University, box 535, 75121 Uppsala (Sweden)

2007-01-01

43

Determination of electron polytropic indices in the environment of Comet P/Halley  

NASA Astrophysics Data System (ADS)

We present a general experimental method to investigate the relations between the density variations and the pressure variations for one particle population of a hot collisionless plasma. A complete description is provided of the data analysis technique for an experimental case, from Giotto electron and magnetic field data measured in the environment of Comet P/Halley, used to verify the theory. The correlations between the electron characteristics, density and pressures, and the magnetic field strength are investigated. In this case, the method shows that the relation between the electron density and pressures can be satisfactorily represented by two polytropic laws. The values inferred for the polytropic indices strongly differ from those usually found in the literature but are nevertheless fully quantitatively explained from the theoretical analytical calculations.

Mazelle, C.; Belmont, G.

1993-01-01

44

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

E-print Network

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

Bini, Donato; Filippi, Simonetta; Geralico, Andrea

2014-01-01

45

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

E-print Network

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

Donato Bini; Christian Cherubini; Simonetta Filippi; Andrea Geralico

2014-08-20

46

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

SciTech Connect

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.

Lin, Min-Kai, E-mail: mklin924@cita.utoronto.ca [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

2012-07-20

47

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

48

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

SciTech Connect

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.

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

2013-03-10

49

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

E-print Network

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

Vassilis Geroyannis; Georgios Kleftogiannis

2014-06-14

50

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

E-print Network

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

D. Reese; F. Lignières; M. Rieutord

2006-05-19

51

Two separate envelope regions influence induction of brain disease by a polytropic murine retrovirus (FMCF98).  

PubMed

The major determinants involved in neurological disease induction by polytropic murine leukemia virus FMCF98 are encoded by the envelope gene. To map these determinants further, we produced four chimeras which contained neurovirulent FMCF98 envelope sequences combined with envelope sequences from the closely related nonneurovirulent polytropic virus FMCF54. Surprisingly, two chimeric viruses containing completely separate envelope regions from FMCF98 could both induce neurological disease. Clinical signs caused by both neurovirulent chimeras appeared to be indistinguishable from those caused by FMCF98, although the incubation periods were longer. One neurovirulence determinant mapped to the N-terminal portion of gp7O, which contains the VRA and VRB receptor-binding regions, while the other determinant mapped downstream of both of the variable regions. Western blot (immunoblot) analyses and immunohistochemical staining of tissue sections indicated that the variations in neurovirulence of these viruses could not be explained by differences in either the quantitative level or the location of virus expression in the brain. PMID:8676516

Hasenkrug, K J; Robertson, S J; Porti, J; McAtee, F; Nishio, J; Chesebro, B

1996-07-01

52

Charged Condensation  

E-print Network

We consider Bose-Einstein condensation of massive electrically charged scalars in a uniform background of charged fermions. We focus on the case when the scalar condensate screens the background charge, while the net charge of the system resides on its boundary surface. A distinctive signature of this substance is that the photon acquires a Lorentz-violating mass in the bulk of the condensate. Due to this mass, the transverse and longitudinal gauge modes propagate with different group velocities. We give qualitative arguments that at high enough densities and low temperatures a charged system of electrons and helium-4 nuclei, if held together by laboratory devices or by force of gravity, can form such a substance. We briefly discuss possible manifestations of the charged condensate in compact astrophysical objects.

Gregory Gabadadze; Rachel A. Rosen

2007-06-15

53

Global weak solutions to the NavierStokes equations for a 1D viscous polytropic ideal gas  

E-print Network

\\Gamma and v \\Sigma = 0 are assumed. In [8] global generalized solutions to the Cauchy problemGlobal weak solutions to the Navier­Stokes equations for a 1D viscous polytropic ideal gas Song 100080, China E­Mail: zp@math03.math.ac.cn Abstract We prove the existence of global weak solutions

54

Compact monolithic capacitive discharge unit  

DOEpatents

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.

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

2007-06-26

55

Compact Reactor  

SciTech Connect

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.

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

2007-01-30

56

Genetic basis for resistance to polytropic murine leukemia viruses in the wild mouse species Mus castaneus.  

PubMed Central

Cultured cells derived from the wild mouse species Mus castaneus were found to be uniquely resistant to exogenous infection by polytropic mink cell focus-forming (MCF) murine leukemia viruses (MuLVs). This MCF MuLV resistance is inherited as a genetically recessive trait in the progeny of F1 crosses between M. castaneus and MCF MuLV-susceptible laboratory mice. Examination of the progeny of backcrosses demonstrated that susceptibility is inherited as a single gene which maps to chromosome 1. The map location of this gene places it at or near the locus Rmc1, the gene encoding the receptor for MCF/xenotropic MuLVs, suggesting that resistance is mediated by the M. castaneus allele of this receptor. PMID:8551621

Lyu, M S; Kozak, C A

1996-01-01

57

Explosive-powder compaction system  

Microsoft Academic Search

Sandia National Laboratories has developed a pressure-control system and a test fixture to study the behavior of explosive materials during compaction. Both the pressure-control system and the test fixture are self-contained and portable. Explosive materials are compacted in a bridged header charge holder assembly by means of a test fixture and a pneumatic cylinder arrangement. Forces are measured with load

A. P. Montoya; M. L. Reichenbach

1981-01-01

58

Compact Storage  

USGS Multimedia Gallery

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

59

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

NASA Astrophysics Data System (ADS)

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.

Azizur Rahman, M.; Ansari, M.

2014-12-01

60

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

61

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

E-print Network

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

F. Lignieres; M. Rieutord; D. Reese

2006-04-13

62

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

PubMed

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

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

1992-03-01

63

Global Compact  

NSDL National Science Digital Library

The Global Compact is a joint project of the International Labor Organization (ILO), the United Nations Environmental Programme (UNEP), and the Office of the High Commissioner for Human Rights. The site outlines the nine principles drafted at the World Economic Forum on January 31, 1999 to serve as guidelines for world businesses. The principles address three basic areas of concern: human rights, labor standards, and environment. The Global Compact also provides means and methods for enacting these principles, including case studies and research from the ILO and the UNEP. The site's Country Information section is a searchable database of labor, human rights, and environmental information from Abkhyazia to Zimbabwe. The News and Reviews section contains current and archived news, as well as statements about the Global Compact from UN Secretary General Kofi Annan and Secretary General Amnesty International Pierre Sane among others. Here, users will also find an analytical overview of the research and debates over these topics.

64

NFC-Enabled Wireless Charging  

Microsoft Academic Search

This paper summarizes the results of our concept development for NFC-enabled wireless charging -- i.e., an add-on to the existing NFC operating modes that implements charging power transmission and charging power reception with associated control functionality. When compared to dedicated wireless charging solutions, integration of NFC and wireless charging into the same implementation will entail more compact and cost-efficient charging

Esko Strommer; Marko Jurvansuu; Tuomo Tuikka; Arto Ylisaukko-oja; Harri Rapakko; Jarmo Vesterinen

2012-01-01

65

Increased compactibility of acetames after roll compaction.  

PubMed

A common technique for manufacturing granules in a continuous way is the combination of roll compaction and subsequent milling. Roll compaction can considerably impact tableting performance of a material. The purpose of this study was to investigate the influence of roll compaction/dry granulation on the compaction behavior of acetames, a class of active pharmaceutical substances, which are mainly used for the treatment of central nervous diseases. Some representatives of acetames were roll compacted and then compressed into tablets. Compactibility of granules was compared with the compaction behavior of the directly compressed drug powders. In contrast to many other materials, the roll compaction step induced an increase in compactibility for all investigated acetames. Specific surface areas of the untreated and the roll compacted drugs were determined by nitrogen adsorption. The raise in compactibility observed was accompanied by an increase in specific surface area during roll compaction. PMID:20932904

Kuntz, Theresia; Schubert, Martin A; Kleinebudde, Peter

2011-01-01

66

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

SciTech Connect

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.

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

2012-12-20

67

A neutralizable epitope common to the envelope glycoproteins of ecotropic, polytropic, xenotropic, and amphotropic murine leukemia viruses.  

PubMed Central

An epitope common to all classes of murine leukemia viruses (MuLVs) was detected by reactivity of MuLVs with a rat monoclonal antibody (MAb) termed 83A25. The antibody is of the immunoglobulin G2a isotype and was derived after fusion of NS-1 myeloma cells with spleen cells from a Fischer rat immunized with a Friend polytropic MuLV. The antibody reacted with nearly all members of the ecotropic, polytropic, xenotropic, and amphotropic classes of MuLVs. Unreactive viruses were limited to the Friend ecotropic MuLV, Rauscher MuLV, and certain recombinant derivatives of Friend ecotropic MuLV. The presence of an epitope common to nearly all MuLVs facilitated a direct quantitative focal immunofluorescence assay for MuLVs, including the amphotropic MuLVs for which no direct assay has been previously available. Previously described MAbs which react with all classes of MuLVs have been limited to those which react with virion core or transmembrane proteins. In contrast, protein immunoblot and immunoprecipitation analyses established that the epitope reactive with MAb 83A25 resides in the envelope glycoproteins of the viruses. Structural comparisons of reactive and nonreactive Friend polytropic viruses localized the epitope near the carboxyl terminus of the glycoprotein. The epitope served as a target for neutralization of all classes of MuLV with MAb 83A25. The efficiency of neutralization varied with different MuLV isolates but did not correlate with MuLV interference groups. Images PMID:1700832

Evans, L H; Morrison, R P; Malik, F G; Portis, J; Britt, W J

1990-01-01

68

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

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

69

Compact magnetograph  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

70

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

NASA Astrophysics Data System (ADS)

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

Hadley, Kathryn Z.

71

Compact spaces, compact cardinals, and elementary submodels  

Microsoft Academic Search

If M is an elementary submodel and X a topological space, then XM denotes the set X?M given the topology generated by the open subsets of X which are members of M. Call a compact space squashable iff for some M, XM is compact and XM?X. The first supercompact cardinal is the least ? such that all compact X with

Kenneth Kunen

2003-01-01

72

Viral RNAs Are Unusually Compact  

PubMed Central

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

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

2014-01-01

73

Ceramic powder compaction  

SciTech Connect

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.

Glass, S.J.; Ewsuk, K.G. [Sandia National Labs., Albuquerque, NM (United States); Mahoney, F.M. [Norton Co., Worcester, MA (United States)

1995-12-31

74

Extensions of the charged Riemannian Penrose inequality  

NASA Astrophysics Data System (ADS)

In this paper we investigate the extension of the charged Riemannian Penrose inequality to the case where charges are present outside the horizon. We prove a positive result when the charge densities are compactly supported, and present a counterexample when the charges extend to infinity. We also discuss additional extensions to other matter models.

Khuri, Marcus; Weinstein, Gilbert; Yamada, Sumio

2015-02-01

75

Low Mach number two-dimensional hydrodynamic turbulence - Energy budgets and density fluctuations in a polytropic fluid  

NASA Technical Reports Server (NTRS)

Theory suggests that three distinct types of turbulence can occur in the low Mach number limit of polytropic flow: nearly incompressible flows dominated by vorticity, nearly pure acoustic turbulence dominated by compression, and flows characterized by near statistical equipartition of vorticity and compressions. Distinctions between these kinds of turbulence are investigated here by direct numerical simulation of two-dimensional compressible hydrodynamic turbulence. Dynamical scalings of density fluctuations, examination of the ratio of transverse to longitudinal velocity fluctuations, and spectral decomposition of the fluctuations are employed to distinguish the nature of these low Mach number solutions. A strong dependence on the initial data is observed, as well as a tendency for enhanced effects of compressibility at later times and at higher wave numbers, as suggested by theories of nearly incompressible flows.

Ghosh, S.; Matthaeus, W. H.

1992-01-01

76

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

SciTech Connect

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.

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

2013-02-15

77

Interacting generalized ghost polytropic gas model of dark energy with a specific Hubble parameter in LRS Bianchi type-II universe  

NASA Astrophysics Data System (ADS)

We study a spatially homogeneous and anisotropic universe where dark energy interacts with dark matter. To solve the Einstein's field equations, we consider a variation law of Hubble parameter which exhibits a transition of the universe from decelerating phase to the present accelerating phase. It is seen that the model of the universe approaches isotropy under suitable condition and the coincidence parameter is found to be an increasing function of time. We discuss the physical and geometrical properties of the universe which are found to be consistent with recent observation. Moreover, we examine a correspondence between the generalized ghost dark energy and polytropic gas model of dark energy. 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 also investigate the statefinder parameters to characterize different phases of the evolution of the universe.

Rahman, M. Azizur; Ansari, M.

2014-12-01

78

Compact Spaces, Compact Cardinals, and Elementary Submodels  

E-print Network

Compact Spaces, Compact Cardinals, and Elementary Submodels #3; Kenneth Kunen yz July 11, 2002 Abstract If M is an elementary submodel and X a topological space, then XM denotes the set X \\M given than the #12;rst 1-extendible cardinal. 1 Introduction Elementary submodels were #12;rst used in set

Kunen, Ken

79

High-frequency behavior of w-mode pulsations of compact stars  

E-print Network

We study the asymptotic behavior of the quasi-normal modes (QNMs) of w-mode pulsations of compact stars in the high-frequency regime. We observe that both the axial and polar w-mode QNMs attain similar asymptotic behaviors in spite of the fact that they are described by two totally different differential equation systems. We obtain robust asymptotic formulae relating w-mode QNMs of different polarities and different angular momenta. To explore the physical reason underlying such similarity, we first derive a high-frequency approximation for the polar w-mode oscillations to unify the descriptions for both cases. Then, we develop WKB-type analyses for them and quantitatively explain the observed asymptotic behaviors for polytropic stars and quark stars. We also point out that such asymptotic behaviors for realistic stars are strongly dependent on the equation of state near the stellar surface.

Y. J. Zhang; J. Wu; P. T. Leung

2011-01-01

80

Compaction Behavior of Isomalt after Roll Compaction  

PubMed Central

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

Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

2012-01-01

81

Compaction behavior of isomalt after roll compaction.  

PubMed

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

Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

2012-01-01

82

On the Matter Distribution of Galaxy Cluster Containing a Compact Core  

E-print Network

Increasing evidences provided primarily by the cluster lensing and numerical simulations of cluster formation indicate that galaxy clusters may contain compact cores that are substantially smaller than the cores revealed by the X-ray observations of hot intracluster gas. In this paper we present a model that describes how two distinct cores can grow simultaneously as a result of infall from the background dark matter. This model needs a pre-existing localized large fluctuation, which can be the non-Gaussian density peak of the primordial fluctuations, to seed the individual growing cluster. On the other hand, numerous recent observations also show that no strong evolution is detected for galaxy clusters within the redshift up to $z\\sim 0.8$. We therefore present a comparison of observations with the saturated cluster configuration resulting from our infall model. In the saturated state, the predicted compact core mass is about few$\\times 10^{11} M_\\odot$ and the core size about 1 kpc for a cluster mass $\\sim$ several $\\times 10^{15} M_\\odot$ within a radius of 3 Mpc. We have successfully reproduced the dark matter distribution revealed by the gravitational lensing, and the observed radial distributions of cluster galaxies, intracluster gas (i.e., the conventional $\\beta$ model) and baryon fractions in a consistent way. This model, when combined with the observed X-ray surface brightness profiles of clusters, predicts that the overall temperature of intracluster gas has a tendency of radial decline with a mean polytropic index $\\gamma\\approx1.2$. Finally, the so-called $\\beta$ discrepancy finds a natural explanation for such a polytropic gas in our model.

Tzihong Chiueh; Xiang-Ping Wu

1999-11-23

83

Neurovirulence of Polytropic Murine Retrovirus Is Influenced by Two Separate Regions on Opposite Sides of the Envelope Protein Receptor Binding Domain?  

PubMed Central

Changes in the envelope proteins of retroviruses can alter the ability of these viruses to infect the central nervous system (CNS) and induce neurological disease. In the present study, nine envelope residues were found to influence neurovirulence of the Friend murine polytropic retrovirus Fr98. When projected on a three-dimensional model, these residues were clustered in two spatially separated groups, one in variable region B of the receptor binding site and the other on the opposite side of the envelope. Further studies indicated a role for these residues in virus replication in the CNS, although the residues did not affect viral entry. PMID:18579597

Peterson, Karin E.; Pourciau, Susan; Du, Min; LaCasse, Rachel; Pathmajeyan, Melissa; Poulsen, David; Agbandje-McKenna, Mavis; Wehrly, Kathy; Chesebro, Bruce

2008-01-01

84

Compact Propositional Gödel Logics  

Microsoft Academic Search

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

Matthias Baaz; Richard Zach

1998-01-01

85

Compaction properties of isomalt  

Microsoft Academic Search

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

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

2009-01-01

86

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...

87

Radiating Charge  

NSDL National Science Digital Library

The electric field lines from a point charge evolve in time as the charge moves. Watch radiation propagate outward at the speed of light as you wiggle the charge. Stop a moving charge to see bremsstrahlung (braking) radiation. Explore the radiation patterns as the charge moves with sinusoidal, circular, or linear motion. You can move the charge any way you like, as long as you donât exceed the speed of light.

Simulations, Phet I.; Dubson, Michael; Paul, Ariel

2013-02-01

88

Laboratory compaction of cohesionless sands  

E-print Network

on the maximum dry unit weight during compaction. Three different laboratory compaction methods were used: 1) Standard Proctor', 2) Modified Proctor; and 3) Vibrating hammer. The effects of the grain size distribution, particle shape and laboratory compaction...

Delphia, John Girard

2012-06-07

89

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

E-print Network

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 $\\omega_2$ and the moment of inertia $I$, and the $I$-Love-$Q$ relations relating $I$, the quadrupole tidal deformability $\\lambda_2$, and the quadrupole moment $Q$, which have been proposed by Lau, Leung, and Lin [Astrophys. J. {\\bf 714}, 1234 (2010)] and Yagi and Yunes [Science {\\bf 341}, 365 (2013)], respectively. A relativistic universal relation between $\\omega_l$ and $\\lambda_l$ with the same angular momentum $l=2,3,\\ldots$, 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.

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

2015-01-13

90

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

NASA Astrophysics Data System (ADS)

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 ?2 and the moment of inertia I , and the I -Love-Q relations relating I , the quadrupole tidal deformability ?2, 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 ?l and ?l 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.

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

2014-12-01

91

DNA compaction by azobenzene-containing surfactant.  

PubMed

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. PMID:21929022

Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Morozova, Elena; Lysyakova, Ludmila; Kasyanenko, Nina; Santer, Svetlana

2011-08-01

92

'Stutter timing' for charge decay time measurement  

NASA Astrophysics Data System (ADS)

The paper describes the approach of 'stutter timing' that has been developed to improve the accuracy of measuring charge decay times in the presence of noise in compact and portable charge decay test instrumentation. The approach involves starting and stopping the timing clock as the noisy signal rises above and falls below the target threshold voltage level.

Chubb, John; Harbour, John; Pavey, Ian

2011-06-01

93

Computational compact torus experiment  

SciTech Connect

We describe a typical 2D magnetohydrodynamic (MHD) calculation of rundown of plasma in a coaxial, magnetized gun and injection of the plasma and reconnection of the embedded magnetic fields to form a compact toroidal plasma.

Eddleman, J.L.; McNamara, B.; Nash, J.K.; Shearer, J.W.; Turner, W.C.

1980-12-24

94

Compact conformal manifolds  

NASA Astrophysics Data System (ADS)

In this note we begin a systematic study of compact conformal manifolds of SCFTs in four dimensions (our notion of compactness is with respect to the topology induced by the Zamolodchikov metric). Supersymmetry guarantees that such manifolds are Kähler, and so the simplest possible non-trivial compact conformal manifold in this set of geometries is a complex one-dimensional projective space. We show that such a manifold is indeed realized and give a general prescription for constructing complex N-dimensional projective space conformal manifolds as certain small breaking deformations of strongly interacting SCFTs. In many cases, our prescription reduces the construction of such spaces to a study of the chiral ring. We also give an algorithm for constructing more general compact spaces of SCFTs.

Buican, Matthew; Nishinaka, Takahiro

2015-01-01

95

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)

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.

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

2001-01-01

96

DNA compaction by a dendrimer.  

PubMed

At physiological pH, a PAMAM dendrimer is positively charged and can effectively bind negatively charged DNA. Currently, there has been great interest in understanding this complexation reaction both for fundamental (as a model for complex biological reactions) as well as for practical (as a gene delivery material and probe for sensing DNA sequence) reasons. Here, we have studied the complexation between double-stranded DNA (dsDNA) and various generations of PAMAM dendrimers (G3-G5) through atomistic molecular dynamics simulations in the presence of water and ions. We report the compaction of DNA on a nanosecond time scale. This is remarkable, given the fact that such a short DNA duplex with a length close to 13 nm is otherwise thought to be a rigid rod. Using several nanoseconds long MD simulations, we have observed various binding modes of dsDNA and dendrimers for various generations of PAMAM dendrimers at varying charge ratios, and it confirms some of the binding modes proposed earlier. The binding is driven by the electrostatic interaction, and the larger the dendrimer charge, the stronger the binding affinity. As DNA wraps/binds to the dendrimer, counterions originally condensed onto DNA (Na+) and the dendrimer (Cl(-)) get released. We calculate the entropy of counterions and show that there is gain in entropy due to counterion release during the complexation. MD simulations demonstrate that, when the charge ratio is greater than 1 (as in the case of the G5 dendrimer), the optimal wrapping of DNA is observed. Calculated binding energies of the complexation follow the trend G5 > G4 > G3, in accordance with the experimental data. For a lower-generation dendrimer, such as G3, and, to some extent, for G4 also, we see considerable deformation in the dendrimer structure due to their flexible nature. We have also calculated the various helicoidal parameters of DNA to study the effect of dendrimer binding on the structure of DNA. The B form of the DNA is well preserved in the complex, as is evident from various helical parameters, justifying the use of the PAMAM dendrimer as a suitable delivery vehicle. PMID:21171620

Nandy, Bidisha; Maiti, Prabal K

2011-01-20

97

Charge inversion accompanies DNA condensation by multivalent ions  

E-print Network

LETTERS Charge inversion accompanies DNA condensation by multivalent ions K. BESTEMAN, K. VAN EIJK The condensation of stiff, highly charged DNA molecules into compact structures by condensing agents ranging from overcompensate the DNA charge when present at high concentration11 , in turn destabilizing the condensates12

Loss, Daniel

98

Compact groups of galaxies  

E-print Network

Compact groups of galaxies have posed a number of challenging questions. Intensive observational and theoretical studies are now providing answers to many of these, and at the same time, are revealing unexpected new clues about the nature and role of these systems. Most compact groups contain a high fraction of galaxies having morphological or kinematical peculiarities, nuclear radio and infrared emission, and starburst or active galactic nuclei (AGN) activity. They contain large quantities of diffuse gas and are dynamically dominated by dark matter. They most likely form as subsystems within looser associations and evolve by gravitational processes. Strong galaxy interactions result and merging is expected to lead to the ultimate demise of the group. Compact groups are surprisingly numerous, and may play a significant role in galaxy evolution.

Paul Hickson

1997-10-25

99

Take Charge!  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

100

Industrial Optimization Compact Course  

E-print Network

Industrial Optimization Compact Course and Challenge Workshop Optimization plays a crucial role in designing and conducting industrial processes. The potential gains range from saving valuable resources over makers from industry and academia to initiate new projects and to foster new structured collaborations

Kirches, Christian

101

Highly compact composite antenna  

Microsoft Academic Search

The highly compact antenna proposed in this communication consists of a judicious association of equivalent magnetic current source with equivalent electric current source. This composite antenna presents a directivity radiation pattern analogous to one of the microstrip ceramic antennas but can be used at low frequencies. The antenna measurements confirm the promising performances obtained from electromagnetic simulations.

M. Pigeon; C. Morlaas; H. Aubert; B. Souny

2009-01-01

102

Local Microcode Compaction Techniques  

Microsoft Academic Search

Microcode compaction is an essential tool for the compilation of high-level language microprograms into microinstructions with parallel microoperations. Although guaranteeing minimum execution time is an exponentially complex problem, recent research indicates that it is not difficult to obtain practical results. This paper, which assumes no prior knowledge of microprogramming on the part of the reader, surveys the approaches that have

David Landskov; Scott Davidson; Bruce Shriver; Patrick W. Mallett

1980-01-01

103

Local microcode compaction techniques  

E-print Network

Microcode compaction is an essential tool for the compilation of high-level language microprograms into microinstructions with parallel microoperations. Although guaranteeing minimum execution time is an exponentially complex problem, recent research indicates that it is not difficult to obtain practical results. This paper, which

David Landskov; Scott Davidson; Bruce Shriver; Patrick W. Mallett

1980-01-01

104

CHARGE IMBALANCE  

SciTech Connect

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.

Clarke, John

1980-09-01

105

Reservoir compaction and land subsidence  

Microsoft Academic Search

Subsurface hydrocarbon removal induces a reservoir compaction that migrates to the ground surface and causes the land to subside. While compaction depends primarily on the fluid pore pressure drawdown, the thickness and the mechanical compressibility of the depleted formation, the amount of compaction reaching the surface depends on the depth and size of the producing field and the stiffness of

Giuseppe Gambolati; Massimiliano Ferronato; Pietro Teatini

2006-01-01

106

COMPACT EXCHANGERS FOR PHASE CHANGE  

Microsoft Academic Search

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

Vishwas V. Wadekar

107

Compact dc link  

Microsoft Academic Search

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

Flairty

1991-01-01

108

Intensity limitations in compact H{sup minus} cyclotrons  

SciTech Connect

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.

Baartman, R.A.

1995-12-31

109

Charge-pump voltage converter  

DOEpatents

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.

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

2009-11-03

110

Compact multiframe blind deconvolution.  

PubMed

We describe a multiframe blind deconvolution (MFBD) algorithm that uses spectral ratios (the ratio of the Fourier spectra of two data frames) to model the inherent temporal signatures encoded by the observed images. In addition, by focusing on the separation of the object spectrum and system transfer functions only at spatial frequencies where the measured signal is above the noise level, we significantly reduce the number of unknowns to be determined. This "compact" MFBD yields high-quality restorations in a much shorter time than is achieved with MFBD algorithms that do not model the temporal signatures; it may also provide higher-fidelity solutions. PMID:21403711

Hope, Douglas A; Jefferies, Stuart M

2011-03-15

111

Compact LINAC for deuterons  

SciTech Connect

We are developing a compact deuteron-beam accelerator up to the deuteron energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IHPMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.

Kurennoy, S S [Los Alamos National Laboratory; O' Hara, J F [Los Alamos National Laboratory; Rybarcyk, L J [Los Alamos National Laboratory

2008-01-01

112

Design of a compact structure cancer therapy synchrotron  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

113

Compaction of Titanium Powders  

SciTech Connect

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

Gerdemann, Stephen,J; Jablonski, Paul, J

2011-05-01

114

Compaction of Titanium Powders  

NASA Astrophysics Data System (ADS)

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

Gerdemann, Stephen J.; Jablonski, Paul D.

2011-05-01

115

Compact electrostatic comb actuator  

DOEpatents

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).

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

2000-01-01

116

Charged Leptons  

E-print Network

This is the report of the Intensity Frontier Charged Lepton Working Group of the 2013 Community Summer Study "Snowmass on the Mississippi", summarizing the current status and future experimental opportunities in muon and tau lepton studies and their sensitivity to new physics. These include searches for charged lepton flavor violation, measurements of magnetic and electric dipole moments, and precision measurements of the decay spectrum and parity-violating asymmetries.

Albrecht, J; Babu, K; Bernstein, R H; Blum, T; Brown, D N; Casey, B C K; Cheng, C -h; Cirigliano, V; Cohen, A; Deshpande, A; Dukes, E C; Echenard, B; Gaponenko, A; Glenzinski, D; Gonzalez-Alonso, M; Grancagnolo, F; Grossman, Y; Harnik, R; Hitlin, D G; Kiburg, B; Knoepfe, K; Kumar, K; Lim, G; Lu, Z -T; McKeen, D; Miller, J P; Ramsey-Musolf, M; Ray, R; Roberts, B L; Rominsky, M; Semertzidis, Y; Stoeckinger, D; Talman, R; Van De Water, R; Winter, P

2013-01-01

117

Charge Challenge  

NSDL National Science Digital Library

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

2012-06-26

118

Compact, Pneumatically Actuated Filter Shuttle  

NASA Technical Reports Server (NTRS)

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.

Leighy, Bradley D.

2003-01-01

119

Charge without charge in quarks  

E-print Network

With appropriate gauge transformations, field can replace electric charge in quarks. Classical quarks, in a necessary non-gauge invariant formulation, are used for illustration, bringing to the fore the lim- itations of the usual electric charge densities for single particles in Coulomb equations. The results are encouraging; the solutions for the Coulomb potentials apply individually to each quark in a shell struc- ture. A remarkably simple relation emerges between the Coulomb and weak potentials.

Harry Schiff

2013-08-06

120

Compact vacuum insulation  

DOEpatents

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.

Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

1993-01-01

121

Compact vacuum insulation embodiments  

DOEpatents

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.

Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

1992-01-01

122

Compact vacuum insulation  

DOEpatents

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.

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

1993-01-05

123

Compact acoustic refrigerator  

SciTech Connect

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.

Bennett, G.A.

1991-12-31

124

Compact acoustic refrigerator  

DOEpatents

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.

Bennett, G.A.

1992-11-24

125

Multipurpose Compact Spectrometric Unit  

SciTech Connect

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.

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

2009-11-09

126

Charge Falling Through a Charged Ring Model  

NSDL National Science Digital Library

The Charge Falling Through a Charged Ring shows dynamics of a charged ball as it is released and falls through a ring of charge. The ball and the ring can be charged with a positive blue) or a (red) negative charge.

Krizaj, Dejan

2010-11-09

127

SOIL COMPACTION SENSING AND MANAGEMENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

As agricultural machinery has become larger and tillage practices have changed in recent decades, compaction as a result of mechanically applied forces such as traction or tillage has caused increasing concern. Amelioration of compaction generally requires some form of deep tillage, increasing costs...

128

Engineering Prototype for a Compact Medical Dielectric Wall Accelerator  

SciTech Connect

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.

Zografos, Anthony; Hening, Andy; Joshkin, Vladimir; Leung, Kevin; Pearson, Dave; Pearce-Percy, Henry; Rougieri, Mario; Parker, Yoko; Weir, John [CPAC, Livermore, CA (United States); Blackfield, Donald; Chen, Yu-Jiuan; Falabella, Steven; Guethlein, Gary; Poole, Brian [Lawrence Livermore National Laboratory, Livermore, CA (United States); Hamm, Robert W. [R and M Technical Enterprises, Pleasanton, CA (United States); Becker, Reinard [Scientific Software Service, Gelnhausen (Germany)

2011-12-13

129

Holding Charge  

NSDL National Science Digital Library

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

Muller, Eric

1995-01-01

130

A Compact Ring Design with Tunable Momentum Compaction  

SciTech Connect

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.

Sun, Y.; /SLAC; ,

2012-05-17

131

Effect of CSR shielding in the compact linear collider  

E-print Network

The Drive Beam complex of the Compact Linear Collider must use short bunches with a large charge making beam transport susceptible to unwanted effects of Coherent Synchrotron Radiation emitted in the dipole magnets. We present the effects of transporting the beam within a limited aperture which decreases the magnitude of the CSR wake. The effect, known as CSR shielding, eases the design of key components of the facility.

Esberg, J; Apsimon, R; Schulte, D

2014-01-01

132

Chandrasekhar's perturbation method-oriented theories Third-order results for uniformly and differentially rotating polytropic stars; reliability and accuracy of first- and second-order results for uniform rotation  

NASA Astrophysics Data System (ADS)

The aim of this investigation is the computation, by implementation of algorithms of a third-order perturbation theory developed in an earlier paper, of numerical results that represent quantitatively the distortion of the structure of a polytropic star, distortion owing to either uniform or differential rapid rotation. The results presented are systematically compared with those of previous investigations. Reliability and accuracy of firstand second-order results are also discussed. The FORTAN program implementing the codes of the theory is extensively described and specifically documented.

Geroyannis, V. S.; Valvi, F. N.

1985-12-01

133

Compact vacuum insulation  

DOEpatents

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.

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

1992-10-27

134

Compact vacuum insulation  

DOEpatents

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.

Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

1992-01-01

135

Compact THz imaging detector  

NASA Astrophysics Data System (ADS)

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 ?m x 300 ?m 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.

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

136

Compact Dexterous Robotic Hand  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

137

Collective Deceleration: Toward a Compact Beam Dump  

SciTech Connect

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.

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

2011-11-28

138

A compact electron spectrometer for an LWFA.  

SciTech Connect

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.

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

2007-01-01

139

Charged poles?  

NSDL National Science Digital Library

A significant portion of the recent work in the field of physics education research has been concerned with the identification of alternate conceptions (Driver and Easley, 1978) that students have about physical systems. Most of this work has been concentrated in the area of mechanics. There has been some work done in the area of electricity and magnetism but, by comparison, this area has received relatively little attention. The author reports on a study designed to determine if student difficulties in understanding the interactions of electric charges with magnetic fields might be caused, at least in part, by an alternate conception. In discussions among physics teachers one often hears several reasons proposed for these difficulties. One reason given is that magnetic force situations are three dimensional. A second one is that the right hand rule is an unusual procedure which is often misunderstood. These matters are almost certainly involved, but might there not also be some alternate conception causing students difficulty? The purpose of the study was to determine whether the students thought of magnetic poles as exerting forces directly on electric charges, in a manner similar to the behaviour of electrostatic charges.

Maloney, David

2006-05-24

140

Compact Holographic Data Storage  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

141

Compact, Reliable EEPROM Controller  

NASA Technical Reports Server (NTRS)

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.

Katz, Richard; Kleyner, Igor

2010-01-01

142

Compact dc link  

SciTech Connect

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.

Flairty, C. (General Electric Co., Malvern, PA (United States))

1991-10-01

143

New considerations for compact cyclotrons  

E-print Network

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

Marshall, Eric S. (Eric Scott)

2012-01-01

144

MESOSCALE SIMULATIONS OF POWDER COMPACTION  

SciTech Connect

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.

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

2009-12-28

145

Compact bilinear operators and commutators  

E-print Network

A notion of compactness in the bilinear setting is explored. Moreover, commutators of bilinear Calderón-Zygmund operators and multiplication by functions in a certain subspace of the space of functions of bounded mean oscillations are shown...

Bé nyi, Á rpá d; Torres, Rodolfo H.

2013-07-01

146

New results on compact structures  

NASA Astrophysics Data System (ADS)

We investigate the presence of localized solutions in models described by a single real scalar field with generalized dynamics. The study offers a method to solve very intricate nonlinear ordinary differential equations, and we illustrate the results with some examples on localized structures with compact profile, in models with polynomial and nonpolynomial interactions. We also show that the compact solutions we have found are all linearly stable.

Bazeia, D.; Losano, L.; Menezes, R.

2014-04-01

147

Compaction in Igneous Rocks (Invited)  

NASA Astrophysics Data System (ADS)

There is increasing evidence that compaction happens in a variety of igneous rocks during solidification, having been described in rocks ranging from thick basaltic flows to layered intrusions. The evidence includes 1) bent mineral grains, 2) development of foliations without a lineation consistent with pure shear, 3) reverse fractionation trends observed at the base of many layered intrusions, and 4) geochemical evidence of progressive loss of elements with increasing incompatibility as pore space is reduced by the combined effects of compaction and solidification of interstitial liquid. Modeling shows that a variety of apparently non-intuitive phenomenon besides simple loss of pore space can occur during compaction. For example, in a compacting pile that is cooling and solidifying from above, compaction becomes more effective with distance below the top owing to higher permeability away from the cooling contact and can lead to dilation of the solid matrix in the mush. This can express itself in the formation of segregation sheets in thick lava flows to possibly the formation of modal layering in thick sills and layered intrusions. Alternatively, compaction in a mush zone that has a density change in the solid assemblage, such as across an ultramafic-mafic contact, can lead to higher porosity zones within the rock with the higher density difference between solid and liquid. These also tend to be areas where platinum-group element and sulfide enrichments can also occur. The observation that compaction occurs in a wide variety of igneous rocks suggests that “cumulate” rocks are nothing more than partly crystallized basalts that have undergone extensive textural and compositional modification during compaction. This can explain why plagioclase, a mineral that otherwise has a neutral to positive buoyancy in most basaltic liquid, is actually the most commonly observed "settled" mineral in layered intrusions.

Boudreau, A. E.

2009-12-01

148

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

PubMed Central

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

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

2009-01-01

149

Compact Optoelectronic Compass  

NASA Technical Reports Server (NTRS)

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

Christian, Carl

2004-01-01

150

Charge Equilibrium  

NASA Astrophysics Data System (ADS)

The mean equililibrium charge of a penetrating ion can be estimated on the basis of Bohr's velocity criterion or Lamb's energy criterion. Qualitative and quantitative results are derived on the basis of the Thomas-Fermi model of the atom, which is discussed explicitly. This includes a brief introduction to the Thomas-Fermi-Dirac model. Special attention is paid to trial function approaches by Lenz and Jensen as well as Brandt and Kitagawa. The chapter also offers a preliminary discussion of the role of the stopping medium, gas-solid differences, and a survey of data compilations.

Sigmund, Peter

151

Charged Membranes  

NSDL National Science Digital Library

This Teaching Resource provides three animated lessons that describe the storage and utilization of energy across plasma membranes. The “Na,K ATPase” animation explains how these pumps establish the electrochemical gradient that stores energy across plasma membranes. The “ATP synthesizing complexes” animation shows how these complexes transfer energy from the inner mitochondrial membrane to adenosine triphosphate (ATP). The “action potential” lesson explains how charged membranes are used to propagate signals along the axons of neurons. These animations serve as valuable resources for any collegiate-level course that describes these important factors. Courses that might employ them include introductory biology, biochemistry, biophysics, cell biology, pharmacology, and physiology.

Jack D. Thatcher (Lewisburg; West Virginia School of Osteopathic Medicine REV)

2013-04-16

152

Get Charged!  

NSDL National Science Digital Library

Students are introduced to the idea of electrical energy. They learn about the relationships between charge, voltage, current and resistance. They discover that electrical energy is the form of energy that powers most of their household appliances and toys. In the associated activities, students learn how a circuit works and test materials to see if they conduct electricity. Building upon a general understanding of electrical energy, they design their own potato power experiment. In two literacy activities, students learn about the electrical power grid and blackouts.

Integrated Teaching And Learning Program

153

Soil Compaction College of Agricultural Sciences  

E-print Network

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

Kaye, Jason P.

154

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

NASA Astrophysics Data System (ADS)

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.

Rindler, Filip

2015-01-01

155

Non-Compact Cardiomyopathy or Ventricular Non-Compact Syndrome?  

PubMed Central

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

2014-01-01

156

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

NASA Astrophysics Data System (ADS)

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.

Rindler, Filip

2014-08-01

157

Gyromagnetic ratio of rapidly rotating compact stars in general relativity  

E-print Network

We numerically calculate equilibrium configurations of uniformly rotating and charged neutron stars, in the case of insulating material and neglecting the electromagnetic forces acting on the equilibrium of the fluid. This allows us to study the behaviour of the gyromagnetic ratio for those objects, when varying rotation rate and equation of state for the matter. Under the assumption of low charge and incompressible fluid, we find that the gyromagnetic ratio is directly proportional to the compaction parameter M/R of the star, and very little dependent on its angular velocity. Nevertheless, it seems impossible to have g=2 for these models with low charge-to-mass ratio, where matter consists of a perfect fluid and where the collapse limit is never reached.

Jerome Novak; Emmanuel Marcq

2003-06-03

158

Charged particle distributions in Jupiter's magnetosphere  

Microsoft Academic Search

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

Neil Divine; H. B. Garrett

1983-01-01

159

Advanced magnetic calculations for high magnetic field compact ion source  

NASA Astrophysics Data System (ADS)

The design of the advanced electronic cyclotronic resonance ion source (ECRIS) requires relatively high axial and radial magnetic inductions to allow the ECR frequency increase and to take advantage of the subsequent density increase (scaling laws). The last improvements of the commercial rare-earth magnet characteristics open new opportunities for ECRIS and enable the design of very high hexapolar magnetic fields for next generation compact ECRIS. Moreover, the high temperature superconducting (HTS) wires allow designing reliable and compact axial field coils (30 K cooled) at a very effective cost. It is thus very relevant to study a compact hybrid ECRIS using high remanence magnet and HTS technologies. In such a design, the volume of the plasma chamber is a free parameter that can be adjusted to the user requirement. It can be dedicated to very high ionic current production or high charge state production, pulsed, or cw operations. This paper presents the three-dimensional overall simulation of a 3 T axial magnetic field compact ECRIS with a high radial field sextupole composed with several magnet types and reaching ˜1.9 T in front of the radially magnetized magnets. This design study will lead to the building of the 28-40 GHz A-PHOENIX source at the laboratory which will deliver its first beam by the end of 2004.

Thuillier, T.; Curdy, J.-C.; Lamy, T.; Sole, P.; Sortais, P.; Vieux-Rochaz, J.-L.; Voulot, D.

2004-05-01

160

ULTRA-COMPACT ACCELERATOR TECHNOLOGIES FOR APPLICATION IN NUCLEAR TECHNIQUES  

SciTech Connect

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.

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

161

ULTRA-COMPACT ACCELERATOR TECHNOLOGIES FOR APPLICATION IN NUCLEAR TECHNIQUES  

SciTech Connect

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 approx10 MV/m gradients for 10 s of nanoseconds pulses and approx100 MV/m gradients for approx1 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 describe 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.

Sampayan, S.; Caporaso, G.; Chen, Y.-J.; Falabella, S.; Guethlein, G.; Harris, J. R.; Hawkins, S.; Holmes, C.; Nelson, S.; Paul, A. C.; Poole, B.; Sanders, D.; Sitaraman, S.; Sullivan, J.; Wang, L.; Watson, J. [Beam Research Program, Lawrence Livermore National Laboratory, P.O. Box 808, L-645 Livermore, CA 94551 (United States); Carazo, V. [MMech, State College, PA 16803 (United States); Guse, S.; Pearson, D.; Schmidt, R. [CPAC Inc., Livermore, CA 94550 (United States)

2009-12-02

162

Compact intermediates in RNA folding  

SciTech Connect

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.

Woodson, S.A. (JHU)

2011-12-14

163

Ch 16 Electric Charge &Ch 16. Electric Charge & Electric Field  

E-print Network

Ch 16 Electric Charge &Ch 16. Electric Charge & Electric Field Liu UCD Phy1B 2012 #12;I Basic ConceptsI. Basic Concepts Static electricity: charges at rest Electric charge Like charges repel Unlike charges attract Liu UCD Phy1B 2012 #12;Electric ChargeElectric Charge Electron charge: -eElectron charge

Yoo, S. J. Ben

164

Properties of dynamically compacted WIPP salt  

SciTech Connect

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.

Brodsky, N.S.; Hansen, F.D. [Sandia National Labs., Albuquerque, NM (United States); Pfeifle, T.W. [RE/SPEC, Inc., Rapid City, SD (United States)

1996-07-01

165

Thermodynamic instabilities in dense asymmetric nuclear matter and in compact stars  

NASA Astrophysics Data System (ADS)

We investigate the presence of thermodynamic instabilities in compressed asymmetric baryonic matter, reachable in high energy heavy ion collisions, and in the cold ?-stable compact stars. To this end we study the relativistic nuclear equation of state with the inclusion of ?-isobars and require the global conservation of baryon and electric charge numbers. Similarly to the low density nuclear liquid-gas phase transition, we show that a phase transition can occur in dense asymmetric nuclear matter and it is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the electric charge concentration). Such thermodynamic instabilities can imply a very different electric charge fraction Z/A in the coexisting phases during the phase transition and favoring an early formation of ?- particles with relevant phenomenological consequences in the physics of the protoneutron stars and compact stars. Finally, we discuss the possible co-existence of very compact and very massive compact stars in terms of two separate families: compact hadronic stars and very massive quark stars.

Lavagno, A.; Drago, A.; Pagliara, G.; Pigato, D.

2014-07-01

166

Mesoscale Simulations of Power Compaction  

SciTech Connect

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.

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

2009-08-06

167

Superconducting magnets for compact synchrotrons  

SciTech Connect

The design of two bending magnets for a compact synchrotron radiation source is presented which involves a multilayer coil with circular cross-section optionally surrounded by a C-shaped cold iron shielding, and a cold bore. The feasibility of winding such magnets is demonstrated by a test coil.

Krevet, B.; Dustmann, C.; Flessner, H.H.

1988-03-01

168

A compact molecular beam line  

Microsoft Academic Search

A new supersonic molecular beam line has been attached to an existing UHV apparatus. Three different nozzles mounted on a rotatable manipulator allow for independent gas feeds. In this way, dosing sequences with different reactive gases can be carried out within a few minutes. Due to the compact design of the beam line, the apparatus does not forfeit its original

F Giskes; D Glastra van Loon; P Lassing; A W Kleyn

169

MATHEMATICAE More reflections on compactness  

E-print Network

submodel topology on X M, especially in the case when XM is compact. 1. Introduction. We are interested in the extent to which the part of a topological space reflected in an elementary submodel captures the whole space. Given a topological space X, T M, an elementary submodel of some H(), we define XM to be X M

Tall, Franklin D.

170

Compact FPGA implementation of Camellia  

Microsoft Academic Search

We present the smallest FPGA implementation of Camellia for 128-bit key length to date. This architecture was designed for low area and low power applications. Through specific optimizations such as shift registers for storing and scheduling key, distributed RAM for storing data, we achieved compact implementation using only 318 slices at a throughput of 18.41 Mbps on the smallest Xilinx

Panasayya Yalla; Jens-Peter Kaps

2009-01-01

171

Generalized high order compact methods.  

SciTech Connect

The fundamental ideas of the high order compact method are combined with the generalized finite difference method. The result is a finite difference method that works on unstructured, nonuniform grids, and is more accurate than one would classically expect from the number of grid points employed.

Spotz, William F.; Kominiarczuk, Jakub (University of California at Berkeley)

2010-09-01

172

Weakly Charged Cationic Nanoparticles Induce DNA Bending and Strand Separation  

SciTech Connect

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.

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

2012-01-01

173

On Modeling Of Charged Structures Encircling Black Holes  

NASA Astrophysics Data System (ADS)

Results of our recent studies suggest a possibility of existence of halo (off-equatorial) clouds consisting of non-interacting charged test particles encircling compact objects (black holes, neutron stars) surrounded by magnetic fields. Here we upgrade the basic model of such diluted toroidal structures by adding internal properties of the matter like density and pressure, so that we have more feasible description for the real charged matter. We realize it by using the magnetohydrodynamic approach. Namely, we built a model of dielectric (zero conductivity) charged torus moving in strong gravitational and electromagnetic fields in the vicinity of black holes. This approach represents just the opposite one to that of widely used ideal magnetohydrodynamics, where the infinite conductivity is taken into account. However, the zero (or negligible) conductivity seems to be one of the assumptions for the existence of charged tori circling in strong gravitational and electromagnetic fields of compact objects.

Kovar, Jiri; Slany, P.; Stuchlik, Z.; Karas, V.; Cremaschini, C.; Miller, J.

2011-09-01

174

Compaction in the Bushveld Complex  

NASA Astrophysics Data System (ADS)

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.

Boorman, S.; Boudreau, A.

2003-12-01

175

Classification of static charged black holes in higher dimensions  

SciTech Connect

The uniqueness theorem for a static charged higher dimensional black hole containing an asymptotically flat spacelike hypersurface with compact interior and with both degenerate and nondegenerate components of event horizon is proposed. By studies of the near-horizon geometry of degenerate horizons, one was able to eliminate the previous restriction concerning the inequality fulfilled by the charges of the adequate components of the aforementioned horizons.

Rogatko, Marek [Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, pl. Marii Curie-Sklodowskiej 1 (Poland)

2006-06-15

176

A review of hydrocarbon two-phase heat transfer in compact heat exchangers and enhanced geometries  

Microsoft Academic Search

Hydrocarbons are considered as alternative fluids for refrigeration, air-conditioning and heat pump applications. Pure butane, propane or their mixtures can be adopted, but due to their flammable properties, the systems have to be designed in such a way that the refrigerant charge is minimized. Therefore, compact heat exchangers and enhanced geometries are adopted in such systems. In this paper, the

Bernard Thonon

2008-01-01

177

Tank farms compacted low-level waste  

SciTech Connect

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.

Hetzer, D.C.

1997-08-01

178

Tank farms compacted low level waste  

SciTech Connect

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.

Waters, M.S., Westinghouse Hanford

1996-07-01

179

Compact High-Order Accurate Nonlinear Schemes  

Microsoft Academic Search

We develop here compact high-order accurate nonlinear schemes for discontinuities capturing. Such schemes achieve high-order spatial accuracy by the cell-centered compact schemes. Compact adaptive interpolations of variables at cell edges are designed which automatically “jump” to local ones as discontinuities being encountered. This is the key to make the overall compact schemes capture discontinuities in a nonoscillatory manner. The analysis

Xiaogang Deng; Hiroshi Maekawa

1997-01-01

180

Limit theorems on locally compact Abelian groups  

E-print Network

Limit theorems on locally compact Abelian groups M´aty´as Barczy,1 Alexander Bendikov2 and Gyula Subject Classification: 60B10, 60B15 Key words: (Central) limit theorems on locally compact Abelian groups conditions for some limit theorems to hold on general locally compact Abelian groups. Our results complete

Barczy, Mátyás

181

On Homogeneous compact spacetimes Abdelghani Zeghib  

E-print Network

On Homogeneous compact spacetimes Abdelghani Zeghib CNRS, UMPA, ´Ecole Normale Sup´erieure de Lyon. Thus For any co-compact lattice H SL(2, R), SL(2, R/H is a homoge- nous compact spacetime. --------------------------------­ Fundamental example 2 A family of sympathetic groups: Warped Heisenberg groups: family of solvable groups

Zeghib, Abdelghani

182

Compact Metric Information Systems (Extended Abstract)  

Microsoft Academic Search

We present information systems for compact metric spaces using the notions of diameter and strong inclusion of open sets. It is shown that the category of compact metric information systems and metric approximable mappings, dual to the category of compact metric spaces and non-expansive maps, is a partially complete I-category in which canonical solution of domain equations can be found

Abbas Edalat; Michael B. Smyth

1992-01-01

183

Program Assessment:Program Assessment: Academic Learning CompactsAcademic Learning Compacts  

E-print Network

Compacts in Program Assessment 59/13/2005 Academic Learning Compacts Communication Critical Thinking 79/13/2005 Academic Learning Compacts Critical Thinking: outcome activities that require analysis Compacts Critical thinking involves: identifying problems in a situation or organization thinking about

Kaup, David J.

184

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

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2012-04-03

185

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

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2010-10-12

186

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

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2011-10-26

187

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

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2012-10-03

188

76 FR 20044 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact  

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2011-04-11

189

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

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2013-10-03

190

75 FR 17161 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact  

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2010-04-05

191

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

Federal Register 2010, 2011, 2012, 2013

...Compact Council for the National Crime Prevention and Privacy Compact...announce a meeting of the National Crime Prevention and Privacy Compact...Council) created by the National Crime Prevention and Privacy Compact...exchange of criminal history records for licensing,...

2013-04-04

192

Compact torus studies: Final report  

SciTech Connect

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.

Morse, E.C.

1987-06-01

193

Sprouts game on compact surfaces  

E-print Network

Sprouts is a two-player topological game, invented in 1967 by Michael Paterson and John Conway. The game starts with p spots drawn on a sheet of paper, and lasts at most 3p-1 moves : the player who makes the last move wins. Sprouts is a very intricate game and the best known manual analysis only achieved to find a winning strategy up to p=7 spots. Recent computer analysis reached up to p=32. The standard game is played on a plane, or equivalently on a sphere. In this article, we generalize and study the game on any compact surface. First, we describe the possible moves on a compact surface, and the way to implement them in a program. Then, with computer calculation, we observe that the winning player on orientable surfaces seems to be always the same one as on a plane, whereas there are significant differences on non-orientable surfaces.

Lemoine, Julien

2008-01-01

194

Compact lanthanum hexaboride hollow cathode.  

PubMed

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

Goebel, Dan M; Watkins, Ronald M

2010-08-01

195

Compact portable diffraction moire interferometer  

DOEpatents

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.

Deason, Vance A. (Shelley, ID); Ward, Michael B. (Idaho Falls, ID)

1989-01-01

196

Compact planar microwave blocking filters  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

197

Compact portable diffraction moire interferometer  

DOEpatents

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.

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

1988-05-23

198

Compact magnetic energy storage module  

DOEpatents

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.

Prueitt, Melvin L. (Los Alamos, NM)

1994-01-01

199

Compact magnetic energy storage module  

DOEpatents

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.

Prueitt, M.L.

1994-12-20

200

Thixoforming of Stellite Powder Compacts  

NASA Astrophysics Data System (ADS)

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.

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

2007-04-01

201

Prediction of reservoir compaction and surface subsidence  

SciTech Connect

A new loading-rate-dependent compaction model for unconsolidated clastic reservoirs is presented that considerably improves the accuracy of predicting reservoir rock compaction and surface subsidence resulting from pressure depletion in oil and gas fields. The model has been developed on the basis of extensive laboratory studies and can be derived from a theory relating compaction to time-dependent intergranular friction. The procedure for calculating reservoir compaction from laboratory measurements with the new model is outlined. Both field and laboratory compaction behaviors appear to be described by one single normalized, nonlinear compaction curve. With the new model, the large discrepancies usually observed between predictions based on linear compaction models and actual (nonlinear) field behavior can be explained.

De Waal, J.A.; Smits, R.M.M.

1988-06-01

202

Gravitational collapse of charged scalar fields  

E-print Network

In order to study the gravitational collapse of charged matter we analyze the simple model of an self-gravitating massless scalar field coupled to the electromagnetic field in spherical symmetry. The evolution equations for the Maxwell-Klein-Gordon sector are derived in the 3+1 formalism, and coupled to gravity by means of the stress-energy tensor of these fields. To solve consistently the full system we employ a generalized Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation of General Relativity that is adapted to spherical symmetry. We consider two sets of initial data that represent a time symmetric spherical thick shell of charged scalar field, and differ by the fact that one set has zero global electrical charge while the other has non-zero global charge. For compact enough initial shells we find that the configuration doesn't disperse and approaches a final state corresponding to a sub-extremal Reissner-N\\"ordstrom black hole with $|Q|charge of the scalar field $q$ we find that the final black hole tends to become more and more neutral. Our results support the cosmic censorship conjecture for the case of charged matter.

Jose M. Torres; Miguel Alcubierre

2014-07-29

203

Compact Video Microscope Imaging System Implemented in Colloid Studies  

NASA Technical Reports Server (NTRS)

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.

McDowell, Mark

2002-01-01

204

A compact LED-based module for DNA capillary electrophoresis  

NASA Astrophysics Data System (ADS)

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

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

2008-11-01

205

Intense Pulsed Neutron Emission from a Compact Pyroelectric Driven Accelerator  

SciTech Connect

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.

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

2008-10-08

206

Charge and Carry  

NSDL National Science Digital Library

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

2012-06-26

207

Compaction of Space Mission Wastes  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

208

Compact pulse forming line using barium titanate ceramic material  

NASA Astrophysics Data System (ADS)

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 ? 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.

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

2011-11-01

209

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

E-print Network

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 behaviour. 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 (EMRIs) as well as astrophysical plasmas relevant e.g. in the formation of accretion discs and polar jets of compact objects.

Yves Brihaye; Valeria Diemer; Betti Hartmann

2014-03-27

210

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

NASA Astrophysics Data System (ADS)

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.

Brihaye, Yves; Diemer, Valeria; Hartmann, Betti

2014-04-01

211

Compact inline optical electron polarimeter.  

PubMed

A compact optical electron polarimeter using a helium target is described. It offers a maximum fluorescence detection efficiency of ~20 Hz/nA, which is an order of magnitude higher than that of earlier designs. With an argon target, this device is expected to have a polarimetric figure-of-merit of 270 Hz/nA. By relying on a magnetic field to guide a longitudinally spin-polarized electron beam, the present instrument employs fewer electrodes. It also uses a commercially available integrated photon counting module. These features allow it to occupy a smaller volume and make it easier to operate. PMID:23742538

Pirbhai, M; Ryan, D M; Richards, G; Gay, T J

2013-05-01

212

A compact fiber optic accelerator  

NASA Astrophysics Data System (ADS)

A compact fiber optic Michelson interferometer based accelerometer is proposed and demonstrated. In this sensing system, two optical fibers have been used as the differential sensing element. By way of demodulating the different optical phase, we can obtain the acceleration which proportional to the initial force applied on the central position of the two fibers. A simple model has been built to calculate the sensitivity and resonant frequency. The experimental results show that such an accelerometer has a sensitivity of 0.42rad/g at the resonant frequency 600Hz.

Peng, Feng; Li, Xingliang; Wu, Bing; Yuan, Yonggui; Yang, Jun; Yuan, Libo

2011-05-01

213

Shock compaction of molybdenum powder  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

214

Two Piece Compaction Die Design  

SciTech Connect

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.

Coffey, Ethan N [ORNL

2010-03-01

215

Compact Radiometers Expand Climate Knowledge  

NASA Technical Reports Server (NTRS)

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.

2010-01-01

216

Abstract--A novel, accurate, compact, and power efficient Lith-ium-Ion (Li-Ion) battery charger designed to yield maximum  

E-print Network

1 Abstract-- A novel, accurate, compact, and power efficient Lith- ium-Ion (Li-Ion) battery charger battery, linear charger, switching charger. I. INTRODUCTION ITHIUM-ION (Li-Ion) batteries are widely used of Li-Ion batteries to over-charged voltages im- poses stringent charge requirements on the design

Rincon-Mora, Gabriel A.

217

Cold compaction of water ice  

USGS Publications Warehouse

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.

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

2005-01-01

218

Compacted carbon for electrochemical cells  

DOEpatents

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.

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

1997-01-01

219

Incompletely compacted equilibrated ordinary chondrites  

SciTech Connect

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.

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

2010-01-22

220

Compacted carbon for electrochemical cells  

DOEpatents

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.

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

1997-10-14

221

Compact Microscope Imaging System Developed  

NASA Technical Reports Server (NTRS)

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.

McDowell, Mark

2001-01-01

222

Prediction of reservoir compaction and surface subsidence  

Microsoft Academic Search

A new loading-rate-dependent compaction model for unconsolidated clastic reservoirs is presented that considerably improves the accuracy of predicting reservoir rock compaction and surface subsidence resulting from pressure depletion in oil and gas fields. The model has been developed on the basis of extensive laboratory studies and can be derived from a theory relating compaction to time-dependent intergranular friction. The procedure

J. A. De Waal; R. M. M. Smits

1988-01-01

223

Compact approach to fusion power reactors  

SciTech Connect

The potential of the Reversed-Field Pinch (RFP) for development into an efficient, compact, copper-coil fusion reactor has been quantified by comprehensive parametric tradeoff studies. These compact systems promise to be competitive in size, power density, and cost to alternative energy sources. Conceptual engineering designs that largely substantiate these promising results have since been completed. This 1000-MWe(net) design is described along with a detailed rationale and physics/technology assessment for the compact approach to fusion.

Hagenson, R.L.; Krakowski, R.A.; Bathke, C.G.; Miller, R.L.

1984-01-01

224

Method for preparing porous metal hydride compacts  

DOEpatents

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.

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

1980-01-21

225

Anisotropic charged stellar models in Generalized Tolman IV spacetime  

NASA Astrophysics Data System (ADS)

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.

Murad, Mohammad Hassan; Fatema, Saba

2015-01-01

226

Compact Solid State Cooling Systems: Compact MEMS Electrocaloric Module  

SciTech Connect

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.

None

2010-10-01

227

Compaction of asphalt pavement. Final report  

SciTech Connect

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.

Hughes, C.S.

1989-10-01

228

Sandstone compaction: Basis for porosity predictive capabilities  

SciTech Connect

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.

Houseknecht, D.W.; Dincau, A.R.; Freeman, C.W. (Univ. of Missouri, Columbia (United States))

1991-03-01

229

Charge regulation circuit  

DOEpatents

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

Ball, Don G. (Livermore, CA)

1992-01-01

230

Finding an Unknown Charge  

NSDL National Science Digital Library

Four charges are shown (one is unknown) given in 10-10C that form what is known as a quadrupole. You can measure the potential at any point by dragging the test charge around. Distance is measured in m.

Christian, Wolfgang; Belloni, Mario

2007-01-26

231

Compact Microwave Fourier Spectrum Analyzer  

NASA Technical Reports Server (NTRS)

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.

Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

2009-01-01

232

Uncertainty Principles for Compact Groups  

E-print Network

We establish an operator-theoretic uncertainty principle over arbitrary compact groups, generalizing several previous results. As a consequence, we show that if f is in L^2(G), then the product of the measures of the supports of f and its Fourier transform ^f is at least 1; here, the dual measure is given by the sum, over all irreducible representations V, of d_V rank(^f(V)). For finite groups, our principle implies the following: if P and R are projection operators on the group algebra C[G] such that P commutes with projection onto each group element, and R commutes with left multiplication, then the squared operator norm of PR is at most rank(P)rank(R)/|G|.

Gorjan Alagic; Alexander Russell

2008-08-29

233

Compact laser Doppler choroidal flowmeter  

NASA Astrophysics Data System (ADS)

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.

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

1999-10-01

234

Compact Quantum Cascade Laser Transmitter  

SciTech Connect

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

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

2009-04-01

235

THE MOST DISTANT COMPACT GROUPS  

SciTech Connect

We present photometric and spectroscopic observations of the members of three previously cataloged compact group (CG) candidates at redshifts z > 0.3. These confirm spectroscopic redshifts compatible with being gravitationally bound structures at redshifts 0.3112, 0.3848, and 0.3643, respectively, and then they are the most distant CGs known with spectroscopic confirmation for all their members. The morphological and spectroscopic properties of all their galaxies indicate early types dominated by an old population of stars, with little star formation or nuclear activity. Most of the physical properties derived for the three groups are quite similar to the average properties of CGs at lower redshifts. In particular, from the velocities and positions of the respective members of each CG, we estimate short dynamic times. These leave open the questions of identifying the mechanism for forming CGs continuously and the nature of the final stages of these structures.

Gutierrez, C. M., E-mail: cgc@iac.es [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)] [Departamento de Astrofisica, Universidad de la Laguna, E-38200 Tenerife (Spain)

2011-08-10

236

Ductile compaction in volcanic conduits  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

237

Physics of Compact Advanced Stellarators  

SciTech Connect

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.

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

238

London's congestion charge  

Microsoft Academic Search

On 17 February 2003, one of the world's largest and most ambitious plans to tackle urban congestion began, with the introduction of a congestion charge for central London. It is hoped that this £5 daily charge for many vehicles entering the Inner Ring Road charging zone will significantly reduce the level of congestion faced by those travelling into and out

L. Blow; A. Leicester; Z. Oldfield

2003-01-01

239

More about Charging Things  

NSDL National Science Digital Library

In the first chapter, you charged things up with excess electrons and saw what could happen as a result. Now we're going to get an idea of how to measure how much charge something has, figure out whether an object is positively or negatively charged, and make up a new concept called the electric field.

Robertson, William C.

2005-01-01

240

Subsurface charge accumulation imaging  

E-print Network

1 Subsurface charge accumulation imaging of a quantum Hall liquid S.H. Tessmer*, P.I. Glicofridis scanning-probe technique-- `subsurface charge accumulation' imaging-- that permits very high resolution-scale electronic structures that exist in the quantum Hall regime. The subsurface charge accumulation (SCA) probe

Tessmer, Stuart

241

Dimensional regularization of a compact dimension  

NASA Astrophysics Data System (ADS)

An extension of dimensional regularization to the case of compact dimensions is presented. The procedure preserves the Kaluza-Klein tower structure, but has a regulator specific to the compact dimension. Possible 5- and 4-dimensional divergent as well as manifest finite contributions of (one-loop) Feynman graphs can easily be identified in this scheme.

Groot Nibbelink, Stefan

2001-12-01

242

Reservoir compaction loads on casings and liners  

Microsoft Academic Search

Pressure drawdown due to production from a reservoir causes compaction of the reservoir formation which induces axial and radial loads on the wellbore. Reservoir compaction loads increase during the production life of a well, and are greater for deviated wells. Presented here are casing and liner loads at initial and final pressure drawdowns for a particular reservoir and at well

G. R. Wooley; W. Prachner

1984-01-01

243

Reservoir Compaction Loads on Casings and Liners  

Microsoft Academic Search

Pressure drawdown resulting from production causes compaction of the reservoir formation, which induces axial and radial loads on the wellbore. Reservoir compaction loads increase during the production life of a well and are greater for deviated wells. Presented here are casing and liner loads at initial and final reservoir pressures for well deviation angles of 0 to 45° (0 to

Gary Wooley; W. Prachner

1988-01-01

244

On Compact Routing for the Internet  

Microsoft Academic Search

The Internet's routing system is facing stresses due to its poor fundamental scaling properties. Compact routing is a research field that studies fundamental limits of routing scalability and designs algorithms that try to meet these limits. In particular, compact routing research shows that shortest-path routing, forming a core of traditional routing algorithms, cannot guarantee routing table (RT) sizes that on

Dmitri V. Krioukov; Kimberly C. Claffy; Kevin R. Fall; Arthur Brady

2007-01-01

245

Compacted Soil Liner Interface Strength Importance  

E-print Network

Case Study Compacted Soil Liner Interface Strength Importance Timothy D. Stark, F.ASCE1 ; Hangseok interface is not the geomembrane (GM)/compacted low-permeability soil liner (LPSL) but a soil­soil interface placing the cover soil from bottom to top. DOI: 10.1061/(ASCE)GT.1943-5606 .0000556. © 2012 American

246

Compact reactor\\/ORC power source  

Microsoft Academic Search

A compact power source that combines an organic Rankine Cycle (ORC) electric generator with a nuclear reactor heat source is being designed and fabricated. Incorporating existing ORC technology with proven reactor technology, the compact reactor\\/ORC power source offers high reliability while minimizing the need for component development. Thermal power at 125 kWt is removed from the coated particle fueled, graphite

K. L. Meier; W. L. Kirchner; G. J. Willcutt

1986-01-01

247

Compact modeling of Double-Gate MOSFETs  

E-print Network

model. Compact model for quantum mechanical effect is alsoquantum mechanical effect can be implemented as an effective change of the gate work function in the compact modelquantum mechanical effect for the sake of simplicity. In this chapter, we present an analytical model

Lu, Huaxin

2006-01-01

248

Hydraulic conductivity tests on compacted clay  

Microsoft Academic Search

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

Stephen S. Boynton; David E. Daniel

1985-01-01

249

Weighted Compact Scheme for Shock Capturing  

Microsoft Academic Search

In this paper a new class of finite difference schemes - the Weighted Compact Schemes are proposed. According to the idea of the WENO schemes, the Weighted Compact Scheme is constructed by a combination of the approximations of derivatives on candidate stencils with properly assigned weights so that the non-oscillatory property is achieve when discontinuities appear. The primitive function reconstruction

Li Jiang; Hua Shan; Chaoqun Liu

2001-01-01

250

Homogeneous test specimens from gyratory compaction  

Microsoft Academic Search

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

P. M. Muraya

2007-01-01

251

On the twin paradox in a universe with a compact dimension  

E-print Network

We consider the twin paradox of special relativity in a universe with a compact spatial dimension. Such topology allows two twin observers to remain inertial yet meet periodically. The paradox is resolved by considering the relationship of each twin to a preferred inertial reference frame which exists in such a universe because global Lorentz invariance is broken. The twins can perform "global" experiments to determine their velocities with respect to the preferred reference frame (by sending light signals around the cylinder, for instance). Here we discuss the possibility of doing so with local experiments. Since one spatial dimension is compact, the electrostatic field of a point charge deviates from $1/r^2$. We show that although the functional form of the force law is the same for all inertial observers, as required by local Lorentz invariance, the deviation from 1/r2 is observer-dependent. In particular, the preferred observer measures the largest field strength for fixed distance from the charge.

Dhruv Bansal; John Laing; Aravindhan Sriharan

2005-03-16

252

Compact dispersion relation for parametric instabilities of electromagnetic waves in dusty plasmas  

SciTech Connect

A compact dispersion relation for parametric instabilities of an electromagnetic pump wave is derived, taking into account the dust-particle dynamics and the {ital dust}-{ital grain} {ital charge} {ital fluctuations} caused by wave motions in unmagnetized dusty plasmas. Specific results for quasistationary modulational and filamentation instabilities are presented. It is found that thresholds of these instabilities are reduced in the presence of quasistationary plasma slow response involving charged dust grains. The present investigation should be useful in understanding the nonlinear propagation of intense electromagnetic waves through dusty space and laboratory plasmas. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Ma, J.X. [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230027 (China)] [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230027 (China); Shukla, P.K. [Institut for Theoretical Physics IV, Department of Physics and Astronomy, Ruhr-University Bochum, D-44780 Bochum (Germany)] [Institut for Theoretical Physics IV, Department of Physics and Astronomy, Ruhr-University Bochum, D-44780 Bochum (Germany)

1995-05-01

253

Compact dispersion relation for parametric instabilities of electromagnetic waves in dusty plasmas  

NASA Astrophysics Data System (ADS)

A compact dispersion relation for parametric instabilities of an electromagnetic pump wave is derived, taking into account the dust-particle dynamics and the dust-grain charge fluctuations caused by wave motions in unmagnetized dusty plasmas. Specific results for quasistationary modulational and filamentation instabilities are presented. It is found that thresholds of these instabilities are reduced in the presence of quasistationary plasma slow response involving charged dust grains. The present investigation should be useful in understanding the nonlinear propagation of intense electromagnetic waves through dusty space and laboratory plasmas.

Ma, J. X.; Shukla, P. K.

1995-05-01

254

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

SciTech Connect

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.

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

255

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

Microsoft Academic Search

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

Min Chen; Gabriel A. Rincon-Mora

2006-01-01

256

X-rays emission from a compact diode energized by capacitor discharge  

NASA Astrophysics Data System (ADS)

X-ray emission from a compact diode consisting of a sharp edged cathode and flat anode of copper and lead, energized by simple capacitor discharge is reported. With a sewing machine needle cathode, and lead target, the generation efficiency upto 0.4% is obtained. The efficiency is expected to enhance further with the increase in discharge energy, charging voltage and reducing the parasitic inductance.

Zakaullah, M.; Ahmed, S.; Hussain, S.; Afzal, M.; Waheed, A.

2005-01-01

257

The RADAN series of compact pulsed power Generators and their applications  

Microsoft Academic Search

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

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

2004-01-01

258

QPL 2005 Preliminary Version Dagger compact closed categories and  

E-print Network

QPL 2005 Preliminary Version Dagger compact closed categories __________________________________________________________________________ Abstract Dagger compact closed categories were recently introduced by Abramsky and Co- ecke, under the name "strongly compact closed categories", as an axiomatic fram* *e- work for quantum mechanics. We

Selinger, Peter

259

QPL 2005 Preliminary Version Dagger compact closed categories and  

E-print Network

QPL 2005 Preliminary Version Dagger compact closed categories and completely positive maps, Nova Scotia, Canada Abstract Dagger compact closed categories were recently introduced by Abramsky and Co- ecke, under the name "strongly compact closed categories", as an axiomatic frame- work

Selinger, Peter

260

MFPS XV Preliminary Version On the compact-regular coreflection  

E-print Network

MFPS XV Preliminary Version On the compact-regular coreflection of a stably compact locale Mart'in H"otzel Escard as the patch frame. We show that the patch construction * *ex- hibits the category of compact regular locales

Escardó, Martín

261

A compaction front in North Sea chalk  

NASA Astrophysics Data System (ADS)

North Sea chalk from 18 wells shows a pronounced porosity drop, from ˜20% to less than 10% over a compaction front of less than 300 m. The position of the compaction front is independent of stratigraphic position, temperature, and actual depth, but closely tied to an effective stress (load stress minus fluid pressure) of ˜17 MPa. These observations require a strongly nonlinear rheology with a marked increase in compaction rate at a specific effective stress. Grain-scale observations demonstrate that the compaction front coincides with marked grain coarsening and recrystallization of fossils and fossil fragments. We propose that this nonlinear rheology is caused by stress-driven failure of the larger pores and the associated generation of reactive surface area by subcritical crack propagation away from these pores. Before the onset of this instability, compaction by pressure solution is slowed down by the inhibitory effect of organic compounds associated with the fossils. Although the compaction mechanism is mainly by pressure solution, the rheological response to burial may still be dominantly plastic and controlled by the (fracturing controlled) rate of exposure of reactive surface area. The nonlinear compaction of chalk has significant implications for the evolution of petroleum systems in the central North Sea, both with respect to sea-floor subsidence above hydrocarbon-producing chalk reservoirs and for the formation of low-porosity pressure seals within the chalk.

Japsen, P.; Dysthe, D. K.; Hartz, E. H.; Stipp, S. L. S.; Yarushina, V. M.; Jamtveit, B.

2011-11-01

262

A compaction front in North Sea chalk  

NASA Astrophysics Data System (ADS)

North Sea chalk from 18 wells shows a pronounced porosity drop, from ˜20% to less than 10% over a compaction front of less than 300 m. The position of the compaction frontis independent of stratigraphic position, temperature, and actual depth, but closely tied to an effective stress of ˜17 MPa. These observations require a strongly nonlinear rheology with a marked increase in compaction rate at a specific effective stress. Grain-scale observations demonstrate that the compaction front coincides with marked grain coarsening and recrystallization of fossils and fossil fragments. We propose that this nonlinear rheology is caused by stress-driven failure of the larger pores and the associated generation of reactive surface area by subcritical crack propagation away from these pores. Before the onset of this instability, compaction by pressure solution is slowed down by the inhibitory effect of organic compounds associated with the fossils. Although the compaction mechanism is mainly by pressure solution, the rheological response to burial may still be dominantly plastic and controlled by the (fracturing controlled) rate of exposure of reactive surface area. The nonlinear compaction of chalk has significant implications for the evolution of petroleum systems in the central North Sea, both with respect to sea-floor subsidence above hydrocarbon-producing chalk reservoirs and for the formation of low-porosity pressure seals within the chalk.

Japsen, P.; Dysthe, D. K.; Hartz, E. H.; Jamtveit, B.

2012-04-01

263

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

264

Spectral responses in granular compaction  

NASA Astrophysics Data System (ADS)

I study the compaction of a granular pack under periodic tapping. The magnitude of acceleration ? at each tap is modulated with frequency ? and amplitude ??: ?(t) = ?DC + ??(?t), where t is time measured by the number of taps. From the temporal modulation ?v in packing volume v, frequency- locked to the modulated tapping input, we can define the real and imaginary volume susceptibilities ?v' = (?v/??) ? and ?v'' = (?v/??) ?; here ? is the phase lag between ?(t) and v(t). As a function of ?DC, ?v', ?v'' are peaked at low ?DC, a behavior reminiscent of the temperature-dependent susceptibilities in dielectric and spin glasses. For the packing of small particles (d = 0.5 mm) in ambient pressure, ?v' exhibits memory and rejuvenation effects under ?DC cycling, similar to that seen in the magnetic susceptibility of spin glasses when subjected to thermal cycling [1]. However this memory effect is suppressed for the packing of larger particles and in vacuum. The measurement of volume susceptibilities shows promise as a new way to study the packing of granular materials, and as an avenue to explore analogies between jammed grains and molecular and spin glasses. [3pt] [1] K. Jonason et al., Phys. Rev. Lett. 81, 3243 (1998).

Zou, Ling-Nan

2009-03-01

265

Application of a compact microwave ion source to radiocarbon analysis  

SciTech Connect

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.

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

1999-04-26

266

Compaction of North-sea chalk  

NASA Astrophysics Data System (ADS)

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)

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

2014-05-01

267

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

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

268

Relativistic solutions of anisotropic compact objects  

NASA Astrophysics Data System (ADS)

We present a class of new relativistic solutions with anisotropic fluid for compact stars in hydrostatic equilibrium. The interior space-time geometry considered here for compact objects are described by parameters namely, ?, k, A, R and n. The values of the geometrical parameters are determined here for obtaining a class of physically viable stellar models. The energy-density, radial pressure and tangential pressure are finite and positive inside the anisotropic stars. Considering some stars of known mass we present stellar models which describe compact astrophysical objects with nuclear density.

Paul, Bikash Chandra; Deb, Rumi

2014-12-01

269

Relativistic Hadrons in Cosmic Compact Objects  

NASA Astrophysics Data System (ADS)

The articles in this book deal with energetic hadron processes near astrophysical compact objects, including compact binary systems and active galactic nuclei. A variety of observational results suggest that relativistic hadrons can be produced in the vicinity of these objects. Among the topics treated in detail are the question whether a large fraction of the energy produced by active galactic nuclei is channeled into a population of relativistic protons and the problem of the origin of very high and ultra-high energy gamma rays from galactic compact sources.

Zdziarski, Andrzej A.; Sikora, Marek

270

Compacting a Kentucky coal for quality logs  

SciTech Connect

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.

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

1999-07-01

271

Shaped charge perforating device  

SciTech Connect

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

Ayers, D.B.

1986-04-22

272

Noncontact charge measurement  

NASA Technical Reports Server (NTRS)

A method for noncontact charge measurements is presented, which uses a system based on the reciprocal motion principle of a grounded conductor near a point charge. The system exhibits extremely good linearity with respect to the input electric field and has a resolution of greater than 10 V/m. The high sensitivity of the apparatus makes the system feasible for use at a safe distance in various applications for monitoring static charge.

Lin, Kuan-Chan; Wang, Taylor G.

1992-01-01

273

Photoionization of Multiply Charged Ions at the Advanced Light Source  

SciTech Connect

Photoionization of multiply charged ions is studied using the merged-beams technique at the Advanced Light Source. An ion beam is created using a compact 10-GHz all-permanent-magnet ECR ion source and is accelerated with a small accelerator. The ion beam is merged with a photon beam from an undulator to allow interaction over an extended path. Absolute photoionization cross sections have been measured for a variety of ions along both isoelectronic and isonuclear sequences.

Schlachter, A.S.; Kilcoyne, A.L.D. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720 (United States); Aguilar, A.; Gharaibeh, M.F.; Emmons, E.D.; Scully, S.W.J.; Phaneuf, R.A. [Department of Physics, MS 220, University of Nevada, Reno NV 89557 (United States); Mueller, A.; Schippers, S. [Institut fuer Atom- und Molekuelphysik, Justus-Liebig-Universitaet, 35392 Giessen (Germany); Alvarez, I.; Cisneros, C.; Hinojosa, G. [Universidad Nacional Autonoma de Mexico, Cuernavaca (Mexico); McLaughlin, B.M. [Queen's University Belfast, BT71NN (United Kingdom)

2005-03-15

274

Charging of interplanetary grains  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

275

Gravitational waves from merging compact binaries  

E-print Network

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

Hughes, Scott A.

276

Steady state compact toroidal plasma production  

DOEpatents

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.

Turner, William C. (Livermore, CA)

1986-01-01

277

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...

278

Pharmaceutical tablet compaction : product and process design  

E-print Network

This thesis explores how tablet performance is affected by microstructure, and how microstructure can be controlled by selection of excipients and compaction parameters. A systematic strategy for formulation and process ...

Pore, Mridula

2009-01-01

279

Compact antenna has symmetrical radiation pattern  

NASA Technical Reports Server (NTRS)

Compact quadrifilar-helix antenna has exceptionally uniform and axially symmetric radiation pattern. It resists shock and vibration and gives excellent radiation characteristics which make it potentially useful for mobile citizenband radios and other terrestrial communications sytems.

Kuhlman, E. A.; Mckee, E. D.

1979-01-01

280

Cosmic Ray Compaction of Porous Interstellar Ices  

NASA Astrophysics Data System (ADS)

We studied the compaction of microporous vapor-deposited ice films under irradiation with different ions in the 80-400 keV energy range. We found that porosity decreases exponentially with irradiation fluence, with a mean compaction area per ion that scales linearly with the stopping power of the projectile S above a threshold St=4 eV Å-1. The experiments roughly follow a universal dependence of ion-induced compaction with restricted dose (eV molecule-1). This behavior can be used to extrapolate our results to conditions of the interstellar medium. Relating our results to ionization rates of interstellar H2, we estimate that porous ice mantles on grains in dense molecular clouds are compacted by cosmic rays in ~10-50 million years.

Raut, U.; Famá, M.; Loeffler, M. J.; Baragiola, R. A.

2008-11-01

281

Reservoir compaction loads on casings and liners  

SciTech Connect

Pressure drawdown resulting from production causes compaction of the reservoir formation, which induces axial and radial loads on the wellbore. Reservoir compaction loads increase during the production life of a well and are greater for deviated wells. Presented here are casing and liner loads at initial and final reservoir pressures for well deviation angles of 0 to 45/sup 0/ (0 to 0.79 rad).

Wooley, G.R.; Prachner, W.

1988-02-01

282

Novel compact circularly polarized square microstrip antenna  

Microsoft Academic Search

A novel compact circular-polarization (CP) operation of the square microstrip antenna with four slits and a pair of truncated corners is proposed and investigated. Experimental results show that the proposed compact CP design can have an antenna-size reduction of about 36% as compared to the conventional corner-truncated square microstrip antenna at a given operating frequency. Also, the required size of

Wen-Shyang Chen; Chun-Kun Wu; Kin-Lu Wong

2001-01-01

283

Compact reflective imaging spectrometer utilizing immersed gratings  

DOEpatents

A compact imaging spectrometer comprising an entrance slit for directing light, a first mirror that receives said light and reflects said light, an immersive diffraction grating that diffracts said light, a second mirror that focuses said light, and a detector array that receives said focused light. The compact imaging spectrometer can be utilized for remote sensing imaging spectrometers where size and weight are of primary importance.

Chrisp, Michael P. (Danville, CA)

2006-05-09

284

Dynamic compaction of tungsten carbide powder.  

SciTech Connect

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.

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

2005-04-01

285

Rain Drop Charge Sensor  

NASA Astrophysics Data System (ADS)

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.

S, Sreekanth T.

286

Phase transformations in shock compacted magnetic materials  

NASA Astrophysics Data System (ADS)

Shock compaction experiments were performed on soft magnetic phases Fe 4N and Fe16N2, and hard magnetic phases Nd 2Fe14B and Sm2Fe17N3 in order to determine their thermo-mechanical stability during shock loading and explore the possibility of fabricating a textured nanocomposite magnet. Gas gun experiments performed on powders pressed in a three capsule fixture showed phase transformations occurring in Fe4N, Fe16N 2, and Nd2Fe14B, while Sm2Fe17 N3 was observed to be relatively stable. Shock compaction of FCC Fe4N resulted in a partial transformation to HCP Fe3N, consistent with previous reports of the transition occurring at a static pressure of ~3 GPa. Shock compaction of Fe16N 2 produced decomposition products ?-Fe, Fe4N, and FeN due to a combination of thermal effects associated with dynamic void collapse and plastic deformation. Decomposition of Nd-Fe-B, producing ?-Fe and amorphous Nd-Fe-B, was observed in several shock consolidated samples and is attributed to deformation associated with shock compaction, similar to decomposition reported in ball milled Nd-Fe-B. No decomposition was observed in shock compacted samples of Sm-Fe-N, which is consistent with literature reports showing decomposition occurring only in samples compacted at a pressure above ~15 GPa. Nd-Fe-B and Sm-Fe-N were shown to accommodate deformation primarily by grain size reduction, especially in large grained materials. Hard/Soft composite magnetic materials were formed by mixing single crystal particles of Nd-Fe-B with iron nanoparticles, and the alignment-by-magnetic-field technique was able to introduce significant texture into green compacts of this mixture. While problems with decomposition of the Nd2Fe14B phase prevented fabricating bulk magnets from the aligned green compacts, retention of the nanoscale morphology of the ?-Fe particles and the high alignment of the green compacts shows promise for future development of textured nanocomposite magnets through shock compaction.

Wehrenberg, Christopher

287

Charging Black Saturn?  

E-print Network

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

Brenda Chng; Robert Mann; Eugen Radu; Cristian Stelea

2008-08-31

288

Compaction Monitoring in the Ekofisk Area Chalk Fields  

Microsoft Academic Search

In late Nov. 1984, the subsidence phenomenon was recognized in the Ekofisk field. To determine the magnitude and areal extent of the formation compaction, a program for measuring compaction with electric logging tools was initiated. Initial time-lapse surveys performed with cased-hole neutron tools indicated that reservoir compaction was occurring, but the accuracy of the determination of compaction rate was low.

M. L. Menghini

1989-01-01

289

Monitoring Compaction and Compressibility Changes in Offshore Chalk Reservoirs  

Microsoft Academic Search

Some of the North Sea's largest and most important oil fields are in chalk reservoirs. In these fields, it is important to measure reservoir compaction and compressibility because compaction can result in platform subsidence. Also, compaction drive is a main drive mechanism in these fields, so an accurate reserves estimate cannot be made without first measuring compressibility. Estimating compaction and

G. A. Dean; R. Hardy; P. Eltvik

1994-01-01

290

Soil Quality Information Sheet Rangeland Soil Quality--Compaction  

E-print Network

Soil Quality Information Sheet Rangeland Soil Quality--Compaction USDA, Natural Resources Conservation Service May 2001 Rangeland Sheet 4 What is compaction? Soil compaction occurs when moist or wet soil aggregates are pressed together and the pore space between them is reduced. Compaction changes

291

MFPS 17 Preliminary Version Stably Compact Spaces and Closed Relations  

E-print Network

MFPS 17 Preliminary Version Stably Compact Spaces and Closed Relations Achim Jung School Abstract Stably compact spaces are a natural generalization of compact Hausdor#11; spaces in the T 0. In this paper we let the morphisms between stably compact spaces be certain \\closed relations" and study

Jung, Achim

292

MFPS XV Preliminary Version On the compact-regular coreflection  

E-print Network

MFPS XV Preliminary Version On the compact-regular coreflection of a stably compact locale Mart frame. We show that the patch construction ex- hibits the category of compact regular locales and continuous maps as a coreflective subcategory of the category of stably compact locales and perfect maps

Escardó, Martín

293

Spacecraft surface charging handbook  

NASA Astrophysics Data System (ADS)

Spacecraft surface charging is the buildup of net electric charge - and therefore electrostatic potential - on the external surfaces of a spacecraft due to incident particles with energies in the kilo-electron volt to tens of kilo-electron volts range. Geosynchronous and low-altitude, polar-orbiting spacecraft encounter charging environments. Surface charging causes problems for operational spacecraft. A primary effect is the occurrence of electronic switching anomalies which can be triggered by differential charging related discharges. The discharge induced transients can cause system failures and potentially, material damage. A more common anomaly is a phantom command, requiring intervention from the ground, and possibly resulting in loss of data and/or expendables, thus shortening the operational lifetime of the spacecraft. The work of the early 1980's provided designers with tools to reduce the number and severity of anomalies. Over the past 10 years, concern has arisen regarding charging on low-altitude, polar orbiting spacecraft due to auroral precipitation. Additionally, with the miniaturization of components, modern spacecraft are more vulnerable to EMI. This handbook was developed to address some of these concerns. The scientific issues of concern in spacecraft surface charging are reviewed, the components of a spacecraft surface charging control plan are described, and the techniques used to avoid spacecraft surface charging problems are summarized. Examples are provided of (1) calculational techniques to evaluate the expected effects of a spacecraft design, and (2) experimental techniques to test immunity to spacecraft surface charging effects. Information on the environments found in the geosynchronous and auroral region and the surface material properties that can affect surfaces are also given.

Davis, V. A.; Gordon, L. W.

1992-11-01

294

Microchannel heat exchangers for charge minimization in air-cooled ammonia condensers and chillers  

Microsoft Academic Search

This paper presents experimental results from a prototype ammonia chiller with an air-cooled condenser and a plate evaporator. The main objectives were charge reduction and compactness of the system. The charge is reduced to 20g\\/kW (2.5oz\\/Ton). This is lower than any currently available air-cooled ammonia chiller on the market. The major contribution comes from use of microchannel aluminum tubes. Two

Pega Hrnjak; Andy D. Litch

2008-01-01

295

Weighted Compact and Non compact Scheme for Shock Tube and Shock Entropy Interaction  

Microsoft Academic Search

[Abstract] In this paper, we introduce a new type of high order shock capturing schemes – uniform weighted compact and non-compact scheme (UWCNC) or simply XJL scheme developed by Xie, Jiang and Liu. This new scheme is based on the feature of discrete data sets instead of the physics. The fundamental task of CFD is to provide an accurate approximation

Peng Xie; Chaoqun Liu

296

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

SciTech Connect

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.

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

297

Relativistically spinning charged sphere  

SciTech Connect

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.

Lynden-Bell, D. [Institute of Astronomy, The Observatories, Madingley Road, Cambridge, CB3 0HA (United Kingdom) and Clare College, Cambridge (United Kingdom)

2004-11-15

298

Shear-enhanced compaction in viscoplastic rocks  

NASA Astrophysics Data System (ADS)

The phenomenon of mutual influence of compaction and shear deformation was repeatedly reported in the literature over the past years. Dilatancy and shear-enhanced compaction of porous rocks were experimentally observed during both rate-independent and rate-dependent inelastic deformation. Plastic pore collapse was preceding the onset of dilatancy and shear-enhanced compaction. Effective bulk viscosity is commonly used to describe compaction driven fluid flow in porous rocks. Experimental data suggest that bulk viscosity of a fluid saturated rock might be a function of both the effective pressure and the shear stress. Dilatancy and shear-enhanced compaction can alter the transport properties of rocks through their influence on permeability and compaction length scale. Recent investigations show that shear stresses in deep mantle rocks can be responsible for spontaneous development of localized melt-rich bands and segregation of small amounts of melt from the solid rock matrix through shear channeling instability. Usually it is assumed that effective viscosity is a function of porosity only. Thus coupling between compaction and shear deformation is ignored. Spherical model which considers a hollow sphere subjected to homogeneous tractions on the outer boundary as a representative elementary volume succeeded in predicting the volumetric compaction behavior of porous rocks and metals to a hydrostatic pressure in a wide range of porosities. Following the success of this simple model we propose a cylindrical model of void compaction and decompaction due to the non-hydrostatic load. The infinite viscoplastic layer with a cylindrical hole is considered as a representative volume element. The remote boundary of the volume is subjected to a homogeneous non-hydrostatic load such that plane strain conditions are fulfilled through the volume. At some critical values of remote stresses plastic zone develops around the hole. The dependence of the effective bulk viscosity on the properties of individual components as well as on the stress state is examined. We show that bulk viscosity is a function of porosity, effective pressure and shear stress. Decreasing porosity tends to increase bulk viscosity whereas increasing shear stress and increasing effective pressure reduce it.

Yarushina, V. M.; Podladchikov, Y. Y.

2012-04-01

299

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

PubMed Central

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

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

2014-01-01

300

Strategy Guideline: Compact Air Distribution Systems  

SciTech Connect

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.

Burdick, A.

2013-06-01

301

Counterintuitive compaction behavior of clopidogrel bisulfate polymorphs.  

PubMed

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

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

2012-07-01

302

Charged anisotropic matter with linear or nonlinear equation of state  

SciTech Connect

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.

Varela, Victor; Rahaman, Farook; Ray, Saibal; Chakraborty, Koushik; Kalam, Mehedi [Institute of Mathematics, Kings College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Department of Mathematics, Jadavpur University, Kolkata 700 032, West Bengal (India); Department of Physics, Government College of Engineering and Ceramic Technology, Kolkata 700 010, West Bengal (India); Department of Physics, Government Training College, Hooghly 712103 (India)

2010-08-15

303

Charged anisotropic matter with linear or nonlinear equation of state  

E-print Network

Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplification 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 non-linear 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 ($10^{19}\\,C$) and maximum electric field intensities are very large ($10^{23}-10^{24}\\,statvolt/cm$) 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.

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

2010-09-04

304

Modulation of folding energy landscape by charge-charge interactions: Linking experiments with computational modeling.  

PubMed

The kinetics of folding-unfolding of a structurally diverse set of four proteins optimized for thermodynamic stability by rational redesign of surface charge-charge interactions is characterized experimentally. The folding rates are faster for designed variants compared with their wild-type proteins, whereas the unfolding rates are largely unaffected. A simple structure-based computational model, which incorporates the Debye-Hückel formalism for the electrostatics, was used and found to qualitatively recapitulate the experimental results. Analysis of the energy landscapes of the designed versus wild-type proteins indicates the differences in refolding rates may be correlated with the degree of frustration of their respective energy landscapes. Our simulations indicate that naturally occurring wild-type proteins have frustrated folding landscapes due to the surface electrostatics. Optimization of the surface electrostatics seems to remove some of that frustration, leading to enhanced formation of native-like contacts in the transition-state ensembles (TSE) and providing a less frustrated energy landscape between the unfolded and TS ensembles. Macroscopically, this results in faster folding rates. Furthermore, analyses of pairwise distances and radii of gyration suggest that the less frustrated energy landscapes for optimized variants are a result of more compact unfolded and TS ensembles. These findings from our modeling demonstrates that this simple model may be used to: (i) gain a detailed understanding of charge-charge interactions and their effects on modulating the energy landscape of protein folding and (ii) qualitatively predict the kinetic behavior of protein surface electrostatic interactions. PMID:25564663

Tzul, Franco O; Schweiker, Katrina L; Makhatadze, George I

2015-01-20

305

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

PubMed

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

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

2015-01-28

306

Photon: history, mass, charge  

E-print Network

The talk consists of three parts. ``History'' briefly describes the emergence and evolution of the concept of photon during the first two decades of the 20th century. ``Mass'' gives a short review of the literature on the upper limit of the photon's mass. ``Charge'' is a critical discussion of the existing interpretation of searches for photon charge. Schemes, in which all photons are charged, are grossly inconsistent. A model with three kinds of photons (positive, negative and neutral) seems at first sight to be more consistent, but turns out to have its own serious problems.

L. B. Okun

2006-02-03

307

taking charge : optimizing urban charging infrastructure for shared electric vehicles  

E-print Network

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

Subramani, Praveen

2012-01-01

308

The birthplace of compact groups of galaxies  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

309

Cylindrically symmetric models of anisotropic compact stars  

NASA Astrophysics Data System (ADS)

In this paper we have discussed the possibility of forming anisotropic compact stars from cosmological constant as one of the competent candidates of dark energy with cylindrical symmetry. For this purpose, we have applied the analytical solution of Krori and Barua metric to a particular cylindrically symmetric spacetime. The unknown constants in Krori and Barua metric have been determined by using masses and radii of class of compact stars like 4 U1820-30, Her X-1, SAX J 1808-3658. The properties of these stars have been analyzed in detail. In this setting the cosmological constant has been taken as a variable which depends on the radial coordinates. We have checked all the regularity conditions, stability and surface redshift of the compact stars 4 U1820-30, Her X-1, SAX J 1808-3658.

Abbas, G.; Nazeer, Sumara; Meraj, M. A.

2014-12-01

310

Compact ultrafast microchannel plate photomultiplier tube  

NASA Astrophysics Data System (ADS)

A new microchannel plate photomultiplier (MCP PMT) has been developed and applied to the time-correlated photon counting technique. The ultrafast MCP PMT with 6 micrometers capillaries, which is the previous type of MCP PMT, was modified. We introduce the new compact and ultrafast MCP PMT and the high-speed electronics designed to be coupled with the MCP PMT. The newly developed compact ultrafast MCP PMT has achieved a time response of 25 psec of transit time spread and is compact in size. In addition, the high-speed amplifier and electronics module (amplifier and constant fraction discriminator) have been developed to deal with the pulses for the MCP PMT. The performance of these devices and their application are presented in this paper.

Kume, Hidehiro; Taguchi, Takeshi; Nakatsugawa, K.; Ozawa, K.; Suzuki, Seiji; Samuel, Reji G.; Nishimura, Yukio; Yamazaki, I.

1992-04-01

311

Detecting compact binary coalescences with seedless clustering  

NASA Astrophysics Data System (ADS)

Compact binary coalescences are a promising source of gravitational waves for second-generation interferometric gravitational-wave detectors. Although matched filtering is the optimal search method for well-modeled systems, alternative detection strategies can be used to guard against theoretical errors (e.g., involving new physics and/or assumptions about spin or eccentricity) while providing a measure of redundancy. In a previous paper, we showed how "seedless clustering" can be used to detect long-lived gravitational-wave transients in both targeted and all-sky searches. In this paper, we apply seedless clustering to the problem of low-mass (Mtotal?10M?) compact binary coalescences for both spinning and eccentric systems. We show that seedless clustering provides a robust and computationally efficient method for detecting low-mass compact binaries.

Coughlin, M.; Thrane, E.; Christensen, N.

2014-10-01

312

Detecting compact binary coalescences with seedless clustering  

E-print Network

Compact binary coalescences are a promising source of gravitational waves for second-generation interferometric gravitational-wave detectors. Although matched filtering is the optimal search method for well-modeled systems, alternative detection strategies can be used to guard against theoretical errors (e.g., involving new physics and/or assumptions about spin/eccentricity) while providing a measure of redundancy. In previous work, we showed how "seedless clustering" can be used to detect long-lived gravitational-wave transients in both targeted and all-sky searches. In this paper, we apply seedless clustering to the problem of low-mass ($M_\\text{total}\\leq10M_\\odot$) compact binary coalescences for both spinning and eccentric systems. We show that seedless clustering provides a robust and computationally efficient method for detecting low-mass compact binaries.

Michael Coughlin; Eric Thrane; Nelson Christensen

2014-08-05

313

Settlement of footing on compacted ash bed  

SciTech Connect

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.

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

2007-11-15

314

Charged Schrodinger black holes  

E-print Network

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

Adams, Allan

315

Gauge Charges from Supergravity  

E-print Network

Some recent results in the study of four dimensional supergravity flux compactifications are reviewed, discussing in particular the role of torsion on the compactification manifold in generating gauge charges for the effective four dimensional theories.

L. Andrianopoli

2005-11-04

316

Charge disproportionation, everywhere!  

Microsoft Academic Search

Charge disproportionation (CD) recently observed in many organic conductors is reviewed. CD is closely related to the charge ordering (CO) but is observed even when no long range CO is established. In a theta -phase BEDT-TTF salt, (BEDT-TTF){2}RbZn(SCN){4}, an extremely slow dynamics of CD has been observed above T_MI. A similar phenomenon is also observed in the Cs-analog, (BEDT-TTF){2}CsZn(SCN){4}. However,

T. Takahashi; K. Hiraki; S. Moroto; N. Tajima; Y. Takano; Y. Kubo; H. Satsukawa; R. Chiba; H. M. Yamamoto; R. Kato; T. Naito

2005-01-01

317

Particle-Charge Spectrometer  

NASA Technical Reports Server (NTRS)

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.

Fuerstenau, Stephen; Wilson, Gregory R.

2008-01-01

318

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

NASA Astrophysics Data System (ADS)

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

Ková?, Ji?í; Slaný, Petr; Stuchlík, Zden?k; Karas, Vladimír; Cremaschini, Claudio; Miller, John C.

2011-10-01

319

Quantizations of compact Lie group actions  

NASA Astrophysics Data System (ADS)

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

Huru, Hilja L.; Lychagin, Valentin V.

2014-06-01

320

Remote vacuum compaction of compressible hazardous waste  

DOEpatents

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.

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

1998-10-06

321

Stuck-at-fault test set compaction  

E-print Network

STUCK-AT-FAULT TEST SET COMPACTION A Sclil&ll I I&)nots I llcsls b)& JASON IVIICHAEL VANEICKELL Submitted to the Office of Honors Pro& rams X Academic Scholarships 1 eras AX&VI Unrvcrsity in p&irtial full'illment ot'the requirements of thc... UNIVERSITY UNDERGRADUATE, RESEARCH I&ELLOWS April 2()04 4'iaJori Colltptltel' Lll&'Ilic&:I ing STUCK-AT-FAULT TEST SET COMPACTION A Senior Honors Thesis by JASON MICHALL VANFICKELL Submitted to the Ot'ttce of'Honors Programs & Academic Sclu...

Vanfickell, Jason Michael

2013-02-22

322

Compact Focal Plane Assembly for Planetary Science  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

323

Perforating gun charge carrier improvements  

SciTech Connect

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

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

1986-07-08

324

Correlation between the charge of proteins in solution and in the gas phase investigated by protein charge ladders, capillary electrophoresis, and electrospray ionization mass spectrometry  

SciTech Connect

Charge ladders of bovine carbonic anhydrase II, hen egg-white lysozyme, and bovine pancreatic trypsin inhibitor, prepared by partial acetylation of primary amino groups on the surface of the protein, have been analyzed by capillary electrophoresis (CE) and on-line electrospray ionization mass spectrometry (ESIMS) using solution conditions that maintain the native structure of the protein. CE was used to separate the proteins that constitute the charge ladder into individual rungs-protein derivatives that have the same number of acetylated amino groups and approximately the same net charge in solution. ESI was used to produce ions i the gas phase of the proteins that constitute each rung of the charge ladder; the mass spectra of these ions were obtained and analyzed. The distributions in charge states observed in the gas phase for the groups of proteins comprising each rung of the charge ladders were narrow, consistent with the retention of a compact structure of the proteins in the gas phase, and substantially independent of the number of acetylated amino groups. The ions observed in the gas phase had surface charge densities in a relatively narrow range of {approximately}0.9--1.5 units of charge per 10{sup 3}{angstrom}{sup 2} of surface area (as estimated from crystallographic structures). These results demonstrate that the distribution of charge states for proteins produced in the gas phase by ESI do not necessarily reflect the net charge of the protein in solution or the number of amino groups on the protein.

Carbeck, J.D.; Gao, J.; Smith, R.D.; Whitesides, G.M. [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology] [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology; Severs, J.C.; Wu, Q. [Pacific Northwest National Lab., Richland, WA (United States). Environmental Molecular Science Lab.] [Pacific Northwest National Lab., Richland, WA (United States). Environmental Molecular Science Lab.

1998-12-17

325

A Novel Spacecraft Charge Monitor for LEO  

NASA Technical Reports Server (NTRS)

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.

Goembel, Luke

2004-01-01

326

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

SciTech Connect

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.

Sun, Yipeng; /SLAC

2012-05-11

327

Status of the North Carolina/Southeast Compact low-level radioactive waste disposal project  

SciTech Connect

The Southeast Compact is a sited region for low-level radioactive waste because of the current facility at Barnwell, South Carolina. North Carolina has been designated as the next host state for the compact, and the North Carolina Low-Level Radioactive Waste Management Authority is the agency charged with developing the new facility. Chem-Nuclear Systems, Inc., has been selected by the Authority as its primary site development and operations contractor. This paper will describe the progress currently being made toward the successful opening of the facility in January 1996. The areas to be addressed include site characterization, performance assessment, facility design, public outreach, litigation, finances, and the continued operation of the Barnwell facility.

Walker, C.K. [North Carolina Low-Level Radioactive Waste Management Authority, NC (United States)

1993-03-01

328

Micro-mechanical modelling of powder compaction  

NASA Astrophysics Data System (ADS)

This paper compares critically a trio of models of the compaction of granular materials in processes of industrial interest. The simplest model assumes an isotropic material with a spheroidal yield surface in principal stress space. The shape of this yield surface is constant but the size is a simple function of the volume strain. The other two models attempt to capture the anisotropic nature of compaction by assuming initially spherical granules that are deformable. One anisotropic model (kinematic) assumes an affine deformation of the centres of the spheres and gives relatively poor quantitative predictions. The other anisotropic model (static) assumes a simple approximation for the values of the contact forces and can be made to give adequate simulations of the compaction of at least some granular materials. Comparison with previously published experimental results shows that at least for some powders the history of anisotropic compaction is carried, not in the overall deformation, but in the maximum force seen by the contacts. Another important new result is that for the case of proportional loading the results of the isotropic model and the static model are in close, but not perfect agreement.

Henderson, R. J.; Chandler, H. W.; Akisanya, A. R.; Chandler, C. M.; Nixon, S. A.

2001-04-01

329

Workability in forging of powder metallurgy compacts  

Microsoft Academic Search

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

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

1995-01-01

330

Compact, Lightweight Servo-Controllable Brakes  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

331

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...

332

FAULT PREDICTIVE CONTROL OF COMPACT DISK PLAYERS  

E-print Network

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

Wickerhauser, M. Victor

333

Compact HVDC converter station design considerations  

Microsoft Academic Search

In this paper, the possible means to reduce HVDC converter station land area requirements are shown. The split-up of real estate between the different kinds of equipment in present-day terminals is analysed. From this, a priority list for suitable action to be taken is deducted. Three concepts of converter valves suitable for compact converter stations are briefly discussed. By example

P. Lips

1976-01-01

334

Persistence, Offline Algorithms, and Space Compaction  

E-print Network

Persistence, Offline Algorithms, and Space Compaction David Eppstein Department of Information [2, 6, 22], and was formalized and classified by Driscoll et al. [8]. In partial persistence, old. In confluent per- sistence, introduced by Driscoll, Sleator, and Tarjan [9], updates combine versions

Eppstein, David

335

7, 1158711619, 2007 A compact and stable  

E-print Network

(IPCC, 2007) and currently 20% of the enhanced greenhouse effect is due to methane (IPCC, 2007 a Creative Commons License. Atmospheric Chemistry and Physics Discussions A compact and stable eddy Discussion EGU 1 Introduction Methane is considered to be the third most important greenhouse gas globally

Boyer, Edmond

336

Near-field compact dielectric optics  

NASA Astrophysics Data System (ADS)

Aplanatic optics crafted from transparent dielectrics can approach the etendue limit for radiative transfer in pragmatic near-field systems. Illustrations are presented for the more demanding realm of high numerical aperture (NA) at the source and/or target. These light couplers can alleviate difficulties in aligning system components, and can achieve the fundamental compactness limit for optical devices that satisfy Fermat's principle.

Feuermann, Daniel; Gordon, Jeffrey M.; Ng, Tuck Wah

2006-08-01

337

Technology Projection Using Simple Compact Models  

Microsoft Academic Search

We review recent efforts to capture the device nonidealities for circuit-level technology projection for Si CMOS. We also give some examples of simple compact model development for assessing the circuit-level performance of exploratory devices such as III-V FET, carbon nanotube transistor, and nanoelectromechanical (NEM) transistors and relays.

H.-S. P. Wong; Lan Wei; S. Oh; A. Lin; Jie Deng; Soogine Chong; K. Akarvardar

2009-01-01

338

Simplicial volume of non-compact manifolds  

E-print Network

Simplicial volume of non-compact manifolds Clara L¨oh April 2008 Abstract. Degree theorems are statements bounding the mapping degree in terms of the volumes of the domain and target manifolds. A possible strategy to ob- tain such degree theorems is to compare the Riemannian volume with a suitable topological

Löh, Clara

339

Compact and localized distributed data structures  

Microsoft Academic Search

This survey concerns the role of data structures for compactly storing and representing various types of in- formation in a localized and distributed fashion. Traditional approaches to data representation are based on global data structures, which require access to the entire structure even if the sought information involves only a small and local set of entities. In contrast, localized data

Cyril Gavoille; David Peleg

2003-01-01

340

Compact attic mounted solar heating pack assembly  

Microsoft Academic Search

A compact attic solar heating pack assembly for mounting within a building attic having south and north facing roof sections overlying a horizontal building attic floor forming the ceiling and defining an enclosed attic space above the occupied room space below the ceiling is described. The pack assembly comprises: a closed sheet metal plenum, means for fixedly mounting the plenum

1988-01-01

341

Simulation of compact heat exchanger performance  

Microsoft Academic Search

Purpose – The purpose of this paper is to present some methods to analyse and determine the performance of compact heat exchangers; show the applicability of various computational approaches and their limitations, provide examples to demonstrate the methods, and present results to highlight the opportunities and limitations of the considered methods. Design\\/methodology\\/approach – Engineering methods based on thermal balances and

Bengt Sunden

2010-01-01

342

Compact muffler apparatus and associated methods  

Microsoft Academic Search

This patent describes a compact muffler for attenuating gas turbine engine noise, comprising: (a) a housing having a rectangular cross-section which circumscribes an axis; (b) an exhaust duct having a rectangular cross-section and extending coaxially through the interior of the housing, the exhaust duct having four side walls, first and second ones of the side walls each having a perforated

D. F. Ross; C. A. Lyon

1987-01-01

343

The Compressor: Concurrent, Incremental, and Parallel Compaction  

E-print Network

Descriptors D.3.4 [Programming Lan- guages]: Processors--Memory management (garbage collection) General Terms Languages, Performance, Algorithms. Keywords Runtime systems, Memory management, Compaction, Garbage, modern servers are required to operate contin- uously and remain highly responsive to extremely frequent

Petrank, Erez

344

A Global Compact to End Poverty  

E-print Network

A Global Compact to End Poverty Jeffrey Sachs on stabilisation, transition and weapons of mass progress. We can realistically envision a world without extreme poverty by the year 2025 because. Sachs, The End of Poverty, 2005. WORLD ECONOMICS · Vol. 6 · No. 4 · October­December 2005 11 Jeffrey D

345

Compaction effects of radiation on Zerodur  

NASA Astrophysics Data System (ADS)

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.

Davis, Mark J.; Fainberg, Jakob

2003-12-01

346

Compact E-Cash Jan Camenisch1  

E-print Network

Compact E-Cash Jan Camenisch1 , Susan Hohenberger2, , and Anna Lysyanskaya3, 1 IBM Research, Zurich schemes are secure in the random oracle model. 1 Introduction Electronic cash was invented by Chaum [22 though the same party (a bank B) is responsible for giving out electronic coins, and for later accepting

Lysyanskaya, Anna

347

HARMONIC TWOSPHERES IN COMPACT SYMMETRIC SPACES, REVISITED  

E-print Network

HARMONIC TWO­SPHERES IN COMPACT SYMMETRIC SPACES, REVISITED F. E. Burstall and M. A. Guest Introduction The purpose of this article is to give a new description of harmonic maps from the two­sphere S 2 of such harmonic maps occur when G=K = S n or CP n . In 1967, E. Calabi gave a construction of all harmonic maps

Bath, University of

348

Compact range for variable-zone measurements  

DOEpatents

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.

Burnside, Walter D. (Columbus, OH); Rudduck, Roger C. (Columbus, OH); Yu, Jiunn S. (Albuquerque, NM)

1988-01-01

349

Compact range for variable-zone measurements  

DOEpatents

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.

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

1987-02-27

350

Compact ranges in antenna and RCS measurements  

Microsoft Academic Search

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

B. Audone

1989-01-01

351

Global Compact for Higher Education Institutions  

E-print Network

, the oldest French-language university in North America, is an institution of international repute and high Compact and Communicating on Progress. In the area of sustainable development, Université Laval, technologies, and practices. Université Laval strives to be a leader in sustainable development. Like other

352

Analysis of Technology for Compact Coherent Lidar  

NASA Technical Reports Server (NTRS)

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

Amzajerdian, Farzin

1997-01-01

353

Potential scattering on conformally compact manifolds  

E-print Network

We prove that the scattering matrix of $\\Delta_g+V$, $g$ conformally compact, $V\\in \\mc^\\infty$, at a fixed energy $\\xi$, $\\xi$ in a suitable subset of $\\mc$, determines the Taylor series of the potential at the boundary.

Marazzi, Leonardo

2008-01-01

354

High Accuracy Compact Schemes and Gibbs' Phenomenon  

Microsoft Academic Search

Compact difference schemes have been investigated for their ability to capture discontinuities. A new proposed scheme (Sengupta, Ganerwal and De (2003). J. Comp. Phys. 192(2), 677.) is compared with another from the literature Zhong (1998). J. Comp. Phys. 144, 622 that was developed for hypersonic transitional flows for their property related to spectral resolution and numerical stability. Solution of the

Tapan K. Sengupta; G. Ganerwal; Anurag Dipankar

2004-01-01

355

Compact advection schemes on unstructured grids  

Microsoft Academic Search

The status of compact cell vertex advection schemes for scalar conservation laws, discretized on unstructured grids composed of triangles of tetrahedra is described. The concepts of fluctuation splitting schemes in one, two, and three dimensions are discussed. Attention is given to a careful definition of upwind concepts in three dimensions and to design criteria to be satisfied by the advection

H. Deconinck; Robert Struijs; G. Bourgois; Philip L. Roe

1993-01-01

356

Folded stubs for compact suspended stripline circuits  

Microsoft Academic Search

Coupled line sections using both sides of a suspended stripline substrate can be regarded as stubs folded closely parallel to the stripline, giving a number of advantages such as compact setup, a simple, one-channel stripline mount, no waveguide modes, and additional degrees of freedom for circuit design. It is shown that, by an appropriate design, open and short-circuited series and

Wolfgang Menzel; F. Hogelsack

1993-01-01

357

Compact flash X-ray units  

Microsoft Academic Search

Flash X-ray units are used to diagnose pulsed power driven experiments on the Pegasus machine at Los Alamos. Several unique designs of Marx powered flash X-ray units have been developed to meet the requirements of the Pegasus experiments. All of these units are compact, battery powered, fiber optically controlled, and EMP shielded. Some of these units are operated with a

D. Platts; M. P. Hockaday; D. Beck; W. Coulter; R. C. Smith

1995-01-01

358

Why Python? 1) readable, compact, simple syntax  

E-print Network

Starting with Python #12;Why Python? 1) readable, compact, simple syntax 2) documented 3) memory of programming effective scripting language 10/19/2010 2 #12;Running simple Scripts >python your_file.py >ls() Python course #12;Basic Datatypes 510/19/2010 Type Example Convert boolean True integer 100000000000019

Spang, Rainer

359

Compact continuum brain model for human electroencephalogram  

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

360

Compactly encoding unstructured inputs with differential compression  

Microsoft Academic Search

The subject of this article is differential compression, the algorithmic task of finding common strings between versions of data and using them to encode one version compactly by describing it as a set of changes from its companion. A main goal of this work is to present new differencing algorithms that (i) operate at a fine granularity (the atomic unit

Miklos Ajtai; Randal C. Burns; Ronald Fagin; Darrell D. E. Long; Larry J. Stockmeyer

2002-01-01

361

Compact Fusion Advanced Rankine (CFARII) power cycle  

Microsoft Academic Search

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

Logan

1991-01-01

362

Compact Ultradense Objects in the Solar System  

E-print Network

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

J. Rafelski; Ch. Dietl; L. Labun

2013-03-19

363

Investigation of HMA compactability using GPR technique  

NASA Astrophysics Data System (ADS)

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."

Plati, Christina; Georgiou, Panos; Loizos, Andreas

2014-05-01

364

Taming Highly Charged Radioisotopes  

NASA Astrophysics Data System (ADS)

The precise and accurate mass of short-lived radioisotopes is a very important parameter in physics. Contribution to the improvement of nuclear models, metrological standard fixing and tests of the unitarity of the Caibbibo-Kobayashi-Maskawa (CKM) matrix are a few examples where the mass value plays a major role. TRIUMF's ion trap for atomic and nuclear physics (TITAN) is a unique facility of three online ion traps that enables the mass measurement of short-lived isotopes with high precision (˜10-8). At present TITAN's electron beam ion trap (EBIT) increases the charge state to increase the precision, but there is no facility to significantly reduce the energy spread introduced by the charge breeding process. The precision of the measured mass of radioisotopes is linearly dependent on the charge state while the energy spread of the charged radioisotopes affects the precision adversely. To boost the precision level of mass measurement at TITAN without loosing too many ions, a cooler Penning trap (CPET) is being developed. CPET is designed to use either positively (proton) or negatively (electron) charged particles to reduce the energy spread via sympathetic cooling. Off-line setup of CPET is complete. Details of the working principles and updates are presented

Chowdhury, Usman; Eberhardt, Benjamin; Jang, Fuluni; Schultz, Brad; Simon, Vanessa; Delheij, Paul; Dilling, Jens; Gwinner, Gerald

2012-10-01

365

Binary fission in damped rotating polytropes  

Microsoft Academic Search

A study is conducted of the instabilities in self-gravitating gases. The study makes use of a numerical method reported by Gingold and Monaghan (1977). The principal features of this method are that the fluid is replaced by a set of fluid elements or particles. The density and other physical fields are obtained by a statistical smoothing procedure. The equations of

R. A. Gingold; J. J. Monaghan

1978-01-01

366

New Frontiers in Spacecraft Charging  

Microsoft Academic Search

Spacecraft charging, as a field, is continually being recharged by new developments in understanding, new materials and technologies, and new approaches to both new and old problems. I will discuss some of the new frontiers in understanding spacecraft charging in this paper, as well as referencing relevant papers from the 11th Spacecraft Charging Technology Conference. Spacecraft charging is highly material-property

Dale C. Ferguson

2012-01-01

367

Fast particles in a steady-state compact FNS and compact ST reactor  

NASA Astrophysics Data System (ADS)

This paper presents results of studies of fast particles (ions and alpha particles) in a steady-state compact fusion neutron source (CFNS) and a compact spherical tokamak (ST) reactor with Monte-Carlo and Fokker–Planck codes. Full-orbit simulations of fast particle physics indicate that a compact high field ST can be optimized for energy production by a reduction of the necessary (for the alpha containment) plasma current compared with predictions made using simple analytic expressions, or using guiding centre approximation in a numerical code. Alpha particle losses may result in significant heating and erosion of the first wall, so such losses for an ST pilot plant have been calculated and total and peak wall loads dependence on the plasma current has been studied. The problem of dilution has been investigated and results for compact and big size devices are compared.

Gryaznevich, M. P.; Nicolai, A.; Buxton, P.

2014-10-01

368

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

E-print Network

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

Schneider, Toby Edwin

369

Charge gradient microscopy.  

PubMed

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

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

2014-05-01

370

Uniform Weighted Compact and Non-Compact Scheme for Shock Entropy Interaction  

Microsoft Academic Search

A new type of high order shock capturing schemes - uniform weighted compact and non-compact scheme (UWCNC) is developed in\\u000a this work. This new scheme is based on the feature of discrete data set. The data are first normalized and then measured by\\u000a so called “smoothness”. The strategy of this new scheme is to achieve spectral-like resolution and high order

Peng Xie; Chaoqun Liu

371

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

NASA Astrophysics Data System (ADS)

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.

Abdullah, M. H.; Rusop, M.

2013-11-01

372

Mathematical relation predicts achievable densities of compacted particles  

NASA Technical Reports Server (NTRS)

Series of mathematical relationships predicts compact densities of spherical shapes in a cylinder as a function of particle dimension, and compact density of angular shapes as a function of particle shape and absolute size.

Ayer, J. E.; Soppet, F. E.

1967-01-01

373

COMPACT SPACES, ELEMENTARY SUBMODELS, AND THE COUNTABLE CHAIN CONDITION  

E-print Network

COMPACT SPACES, ELEMENTARY SUBMODELS, AND THE COUNTABLE CHAIN Abstract. Given a space in an elementary submodel M of H(`), defi* *ne XM to be X \\ M spaces are determined by their compact reflections in* * elementary submodels is investigated. A minor

Larson, Paul B.

374

Charged conformal Killing spinors  

NASA Astrophysics Data System (ADS)

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

Lischewski, Andree

2015-01-01

375

Charge and Carry  

NSDL National Science Digital Library

This site contains an activity on electrostatics. A styrofoam plate is rubbed with wool to give it a large electric charge that can be transferred to an aluminum pie pan. This electrophorus, or change carrier produces a spark that can be felt, seen, and heard. Materials needed, assembly, and an explanation of results are also provided. Also featured are directions to store up an even larger charge in a device called a Leyden jar, made from a plastic film can. This activity is part of Exploratorium's Science Snacks series.

2006-07-21

376

Compact narrow-band THz radiation source based on photocathode rf gun  

NASA Astrophysics Data System (ADS)

Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. We present a scheme of compact THz radiation source based on the photocathode rf gun. On the basis of our analytic result, the subpicosecond electron bunch with high charge (800 pC) can be generated directly in the photocathode rf gun. According to the analytical and simulated results, a narrow emission spectrum peaked at 0.24 THz with 2 megawatt (MW) peak power is expected to gain in the proposed scheme (the length of the facility is about 1.2 m).

Li, Wei-Wei; He, Zhi-Gang; Jia, Qi-Ka

2014-04-01

377

Diffuse-charge dynamics in electrochemical systems  

NASA Astrophysics Data System (ADS)

The response of a model microelectrochemical system to a time-dependent applied voltage is analyzed. The article begins with a fresh historical review including electrochemistry, colloidal science, and microfluidics. The model problem consists of a symmetric binary electrolyte between parallel-plate blocking electrodes, which suddenly apply a voltage. Compact Stern layers on the electrodes are also taken into account. The Nernst-Planck-Poisson equations are first linearized and solved by Laplace transforms for small voltages, and numerical solutions are obtained for large voltages. The “weakly nonlinear” limit of thin double layers is then analyzed by matched asymptotic expansions in the small parameter ?=?D/L , where ?D is the screening length and L the electrode separation. At leading order, the system initially behaves like an RC circuit with a response time of ?DL/D (not ?D2/D ), where D is the ionic diffusivity, but nonlinearity violates this common picture and introduces multiple time scales. The charging process slows down, and neutral-salt adsorption by the diffuse part of the double layer couples to bulk diffusion at the time scale, L2/D . In the “strongly nonlinear” regime (controlled by a dimensionless parameter resembling the Dukhin number), this effect produces bulk concentration gradients, and, at very large voltages, transient space charge. The article concludes with an overview of more general situations involving surface conduction, multicomponent electrolytes, and Faradaic processes.

Bazant, Martin Z.; Thornton, Katsuyo; Ajdari, Armand

2004-08-01

378

Agronomic consequences of tractor wheel compaction on a clay soil  

Microsoft Academic Search

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

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

2005-01-01

379

Effect of die wall lubrication on warm compaction powder metallurgy  

Microsoft Academic Search

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

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

2002-01-01

380

Investigations on Forced Convection in Compact Passages with Surface Irregularities  

Microsoft Academic Search

Two-dimensional, fully developed, convective heat transfer in compact passages is investigated numerically, incorporating the effects of the surface irregularities, to analyze the influence of these irregularities on fluid flow and heat transfer. This analysis helps to bring out the differences in the performance evaluation if regular cross-sections are assumed in analyzing compact and mini channels. Forced convection in compact passages

Binoy Baby; Choondal B. Sobhan

2012-01-01

381

QPL 2005 Preliminary Version Dagger compact closed categories and  

E-print Network

QPL 2005 Preliminary Version Dagger compact closed categories and completely positive maps, Ontario, Canada Abstract Dagger compact closed categories were recently introduced by Abramsky and Co- ecke, under the name "strongly compact closed categories", as an axiomatic frame- work for quantum

Selinger, Peter

382

QPL 2005 Preliminary Version Dagger compact closed categories and  

E-print Network

QPL 2005 Preliminary Version Dagger compact closed categories and completely positive maps, Nova Scotia, Canada Abstract Dagger compact closed categories were recently introduced by Abramsky and Co­ ecke, under the name ``strongly compact closed categories'', as an axiomatic frame­ work

Selinger, Peter

383

High Availability Commodity Computing A CompactPCISystem Evaluation  

E-print Network

High Availability Commodity Computing ­ A CompactPCI­System Evaluation GË?unter Graf, Markus@in.tum.de Abstract This paper examines cost effective high availability sys­ tems based on standardized Compact which tend to be over­ optimistic. Keywords: Availability Modeling, Fault Tolerance, Petri Nets, Compact

Stamatakis, Alexandros

384

Test Vector Decomposition Based Static Compaction Algorithms for Combinational Circuits  

E-print Network

Test Vector Decomposition Based Static Compaction Algorithms for Combinational Circuits Aiman H. El test during test application. Therefore, practical techniques, such as test compression and compaction requirements for the tester. In this paper, a new approach to static compaction for combinational circuits

El-Maleh, Aiman H.

385

Compact E-Cash and Simulatable VRFs Mira Belenkiy1  

E-print Network

Compact E-Cash and Simulatable VRFs Revisited Mira Belenkiy1 , Melissa Chase2 , Markulf Kohlweiss3 (Eurocrypt 2008) to two related cryptographic problems: compact e-cash (Eurocrypt 2005) and simulatable verifiable random functions (CRYPTO 2007). We present the first efficient compact e-cash scheme that does

Lysyanskaya, Anna

386

Generalized Bohr compactication and model-theoretic connected components  

E-print Network

Generalized Bohr compactication and model-theoretic connected components Krzysztof Krupi: [externally] denable Bohr compactication, model-theoretic connected components, denable strong amenability 1-called generalized Bohr compactication from [11]. As mentioned in the abstract, our model-theoretic set-up subsumes

Krupiñski, Krzysztof

387

Approximating Radon measures on first--countable compact spaces  

E-print Network

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

Plebanek, Grzegorz

388

Build a Charge Detector  

NSDL National Science Digital Library

In this hands-on activity, students explore the electrical force that takes place between two objects. Each student builds an electroscope and uses the device to draw conclusions about objects' charge intensity. Students also determine what factors influence electric force.

Integrated Teaching And Learning Program

389

A compact, versatile low-energy electron beam ion source  

SciTech Connect

A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies.

Zschornack, G., E-mail: g.zschornack@hzdr.de [Department of Physics, Dresden University of Technology, 01062 Dresden, Germany and Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, 01328 Dresden (Germany); König, J.; Schmidt, M.; Thorn, A. [DREEBIT GmbH, 01109 Dresden (Germany)] [DREEBIT GmbH, 01109 Dresden (Germany)

2014-02-15

390

Operating single quantum emitters with a compact Stirling cryocooler.  

PubMed

The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g((2))(0) < 0.04 from this Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g((2))(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources. PMID:25638078

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

2015-01-01

391

A compact PE memory for vision chips  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

392

Spinning compact binary dynamics and chameleon orbits  

E-print Network

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

László Árpád Gergely; Zoltán Keresztes

2014-11-14

393

A compact neutron-gamma spectrometer  

NASA Astrophysics Data System (ADS)

A compact neutron/gamma detector has been developed using a liquid scintillator cell coupled to a Flat Panel PMT; performances have been compared with a second cell coupled to a traditional linearly-focused 12 dynodes PMT. Energy resolution and pulse shape discrimination (PSD) measured by using a fast digitizer are very similar for the two detectors with the time resolution of the Flat Panel PMT slightly worse. The new detector results to be weakly affected by the influence of a moderate magnetic field while the traditional PMT exhibits strong pulse reduction. The compact size and the low power consumption obtained by using the Flat Panel PMT are very useful in portable neutron/gamma spectrometers.

Cester, D.; Nebbia, G.; Stevanato, L.; Pino, F.; Sajo-Bohus, L.; Viesti, G.

2013-08-01

394

Acoustic Scattering from Compact Bubble Clouds.  

NASA Astrophysics Data System (ADS)

In this study, a simple model describing the low -frequency scattering properties of high void fraction bubble clouds in both the free field and near the ocean surface is developed. This model, which is based on an effective medium approximation and acoustically compact scatters, successfully predicts the results of the bubble cloud scattering experiment carried out at Lake Seneca in New York state for frequencies consistent with the model assumptions (Roy et al., 1992). The introduction of the surface is facilitated by the method of images and is subject to the same constraint of low-acoustic frequency imposed by the compact scatterer assumption. This model is not intended to serve as an exact replicate of oceanic bubble cloud scattering. The model herein was kept simple by design, for only then can the complex physical behavior be expressed in a simple analytical form. Simple, analytic theories facilitate the exploration of parameter space, and more importantly serve to illuminate the underlying physics.

Schindall, Jeffrey Alan

395

RNA isolation and fractionation with compaction agents  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

396

Compact stars with color superconducting quark matter  

E-print Network

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

Mark Alford; Sanjay Reddy

2002-11-14

397

Metagratings for Diffraction Based, Compact, Holographic Imaging  

NASA Astrophysics Data System (ADS)

Recent developments in semiconductor technology brought to life a new generation of highly-compact visible-frequency cameras. Unfortunately, straight forward extension of this progress to low-frequency domains (such as mid-IR imaging) is impossible since the pixel size at these frequencies is limited by free-space diffraction limit. Here we present an approach to realize highly-compact imaging systems at lower frequencies. Our approach takes advantage of high refractive index of materials commonly utilized in semiconductor detectors of mid-IR radiation, accompanied by metagratings, structures with engineered diffraction properties, to achieve a 10-fold reduction in the pixel size. In contrast to conventional refraction-based imaging, the approach essentially produces a digital hologram -- a 2D projection of the 3D optical field, enabling a post-imaging ``refocusing'' of the picture. The perspectives of numerical recovery of the optical field and the stability of such recovery are discussed.

Inampudi, Sandeep; Podolskiy, Viktor A.

2013-03-01

398

DYNAMICS AND FUNCTION OF COMPACT NUCLEOSOME ARRAYS  

PubMed Central

The packaging of eukaryotic DNA into chromatin sterically occludes polymerases, recombinases and repair enzymes. How chromatin structure changes to allow their actions is unknown. We constructed defined fluorescently labeled trinucleosome arrays, allowing analysis of chromatin conformational dynamics via fluorescence resonance energy transfer (FRET). The arrays undergo reversible Mg2+-dependent folding like that of longer arrays studied previously. We define two intermediate conformational states in the reversible folding of the nucleosome arrays, and characterize the microscopic rate constants. Nucleosome arrays are highly dynamic even when compact, undergoing conformational fluctuations on seconds to microseconds timescales. Compact states of the arrays allow binding to DNA within the central nucleosome via site exposure. Protein binding can also drive decompaction of the arrays. Thus, our results reveal multiple modes by which spontaneous chromatin fiber dynamics allows for the invasion and action of DNA processing protein complexes. PMID:19701201

Poirier, Michael G.; Oh, Eugene; Tims, Hannah S.; Widom, Jonathan

2009-01-01

399

A compact high field magnetic force microscope.  

PubMed

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

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

2014-12-01

400

Spinning compact binary dynamics and chameleon orbits  

NASA Astrophysics Data System (ADS)

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.

Gergely, László Árpád; Keresztes, Zoltán

2015-01-01

401

Midwest reclamation methods combat soil compaction  

SciTech Connect

Soil compaction can be the root of reclamation evils, but various studies are working on solutions to solve the problem. A bucket-wheel excavator conveyor-spreader system, ripping, and other reclamation methods demonstrated during the 7th Midwest Reclamation Tour show promise in reclaiming land to farm and forest use. Held last September and sponsored by Southern Illinois University and the University of Kentucky, the tour surveyed mined lands in southern Illinois and western Kentucky. The tour demonstrated that soil compaction can be reduced with a conveyor-spreader system, subsoiling, soil reconstruction, and by using end-dumps and rippers. Row crop yields were substantially improved on plots where these methods were used. Reforestation methods, however, have shown less success and do not compare with the case or effectiveness of planting trees on ungraded spoil banks as was done before current reclamation laws were established.

Erhart, P.P.

1984-04-01

402

A compact high voltage pulse generator  

SciTech Connect

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

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

1994-07-01

403

Compact 2-D graphical representation of DNA  

NASA Astrophysics Data System (ADS)

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 ?-globin and gorilla ?-globin.

Randi?, Milan; Vra?ko, Marjan; Zupan, Jure; Novi?, Marjana

2003-05-01

404

A physically compact quad ridge horn design  

Microsoft Academic Search

The electrical and mechanical constraints placed on the element design for a very small dual linear polarized broadband phased array has resulted in the development of a physically compact quad-ridge horn antenna. Using its lowest operating frequency, this antenna has an aperture size of1\\/4lambda times 1\\/4lambdaand an axial length of1\\/3lambda. These dimensions represent a reduction in size of approximately 50%

S. Soroka

1986-01-01

405

Compact Quiescent Galaxies at Intermediate Redshifts  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

406

Light, Compact Pumper for Harbor Fires  

NASA Technical Reports Server (NTRS)

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

Burns, R. A.

1983-01-01

407

HVDC link to test compact terminals  

Microsoft Academic Search

A 100-MW dc link to demonstrate compact HVDC application for urban areas is being installed at Consolidated Edison's Astoria station. The purpose of the project is to accelerate development of compressed-gas technology for dc substations; to research, design, and produce equipment that will demonstrate the practicality of full-scale systems; and to provide a prototype test facility to obtain performance, reliability,

F. E. Fischer; A. Glassanos; N. G. Hingorani

1977-01-01

408

A More Compact Representation of XTR Cryptosystem  

Microsoft Academic Search

XTR is one of the most efficient public-key cryptosystems that allow us to compress the communication bandwidth of their ciphertext. The compact representation can be achieved by deploying a subgroup Fq2 of extension field Fq6, so that the compression ratio of XTR cryptosystem is 1\\/3. On the other hand, Dijk et al. proposed an efficient public-key cryptosystem using a torus

Masaaki Shirase; Dong-Guk Han; Yasushi Hibino; Howon Kim; Tsuyoshi Takagi

2008-01-01

409

Compaction effects of radiation on Zerodur  

Microsoft Academic Search

All materials undergo some degree of compaction or expansion 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

Mark J. Davis; Jakob Fainberg

2003-01-01

410

Ultra Compact Three-phase PWM Rectifier  

Microsoft Academic Search

An increasing number of telecom, data server and aircraft power supply applications require high power, highly efficient, compact, sinusoidal input current rectifiers. The design and experimental performance of an 8.5 kW\\/liter (139 W\\/in3), 3-phase PWM rectifier with a power output of 10 kW is presented. The high power density is achieved by increasing the switching frequency up to 400 kHz,

P. Karutz; S. D. Round; M. L. Heldwein; J. W. Kolar

2007-01-01

411

Compact stars in Kaluza -Klein World  

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

412

Compact pulsed laser having improved heat conductance  

NASA Technical Reports Server (NTRS)

A highly efficient, compact pulsed laser having high energy to weight and volume ratios is provided. The laser utilizes a cavity reflector that operates as a heat sink and is essentially characterized by having a high heat conductivity, by being a good electrical insulator and by being substantially immune to the deleterious effects of ultra-violet radiation. Manual portability is accomplished by eliminating entirely any need for a conventional circulating fluid cooling system.

Yang, L. C. (inventor)

1977-01-01

413

Compact optical microfluidic uric acid analysis system  

Microsoft Academic Search

We designed, fabricated and tested a novel compact fluorescence analysis system for quantification of uric acid (UA) in clinical samples at the point-of-care. To perform an analysis, diluted saliva, urine or blood samples are simply placed in a disposable thin-film sample holder using a dropper. A new enzyme immobilization technique was developed to retain within the sample holder two enzymes

Chia-Pin Chang; David J. Nagel; Manuel T. Velasquez; Mona E. Zaghloul

2011-01-01

414

On Compact Storage Models for Gazetteers  

Microsoft Academic Search

This paper describes compact storage models for gazetteers using state-of-the-art finite-state technology. In particular,\\u000a we compare the standard method based on numbered indexing automata associated with an auxiliary storage device, against a\\u000a pure finite-state representation, the latter being superior in terms of space and time complexity, when applied to real-world\\u000a test data. Further, we pinpoint some pros and cons for

Jakub Piskorski

2005-01-01

415

Compact, Automated, Frequency-Agile Microspectrofluorimeter  

NASA Technical Reports Server (NTRS)

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

Fernandez, Salvador M.; Guignon, Ernest F.

1995-01-01

416

Compact phase space, cosmological constant, discrete time  

E-print Network

We study the quantization of geometry in the presence of a cosmological constant, using a discretiza- tion with constant-curvature simplices. Phase space turns out to be compact and the Hilbert space finite dimensional for each link. Not only the intrinsic, but also the extrinsic geometry turns out to be discrete, pointing to discreetness of time, in addition to space. We work in 2+1 dimensions, but these results may be relevant also for the physical 3+1 case.

Rovelli, Carlo

2015-01-01

417

VLBI Observations of Five Compact Radio Sources  

E-print Network

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

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

2000-09-26

418

Compact hydrogen\\/helium isotope mass spectrometer  

Microsoft Academic Search

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

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

1996-01-01

419

ROSAT: X ray survey of compact groups  

NASA Technical Reports Server (NTRS)

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

Vangorkom, Jacqueline

1993-01-01

420

INVERSE SCATTERING ON CONFORMALLY COMPACT MANIFOLDS  

E-print Network

Abstract. We study inverse scattering for ?g + V on (X, g) a conformally compact manifold with metric g, with variable sectional curvature ?? 2 (y) at the boundary and V ? C ? (X) not vanishing at the boundary. We prove that the scattering matrix at a fixed energies (?1, ?2) in a suitable subset of C, determines ?, and the Taylor series of both the potential and the metric at the boundary. 1.

Leonardo Marazzi

421

Compacting music signatures for efficient music retrieval  

Microsoft Academic Search

Music information retrieval is becoming very important with the ever-increasing growth of music content in digital li- braries, peer-to-peer systems and the internet. While it is easy to quantize music into a discrete string representa- tion, retrieval by content requires (approximate) sub-string matching, which is hard. In this paper, we present a novel system, called MUSIG, that uses compact MUsic

Bin Cui; H. V. Jagadish; Beng Chin Ooi; Kian-lee Tan

2008-01-01

422

Ising Analogue to Compact-Star Matter  

SciTech Connect

By constructing an Ising analogue of compact-star matter at subsaturation density we explored the effect of Coulomb frustration on the nuclear liquid-gas phase transition. Our conclusion is twofold. First, the range of temperatures where inhomogeneous phases form expands with increasing Coulomb-field strength. Second, within the approximation of uniform electron distribution, the limiting point upon which the phase-coexistence region ends does not exhibit any critical behavior. Possible astrophysics consequences and thermodynamical connections are discussed.

Napolitani, P. [GANIL (DSM-CEA/IN2P3-CNRS), Boulevard H. Becquerel, F-14076 Caen cedex (France) and LPC - IN2P3-CNRS/Ensicaen et Universite, F-14076 Caen cedex (France); Chomaz, Ph.; Hasnaoui, K. H. O. [GANIL (DSM-CEA/IN2P3-CNRS), Boulevard H. Becquerel, F-14076 Caen cedex (France); Gulminelli, F. [LPC - IN2P3-CNRS/Ensicaen et Universite, F-14076 Caen cedex (France)

2007-03-30

423

Ising analogue to compact-star matter  

E-print Network

By constructing an Ising analogue of compact-star matter at sub-saturation density we explored the effect of Coulomb frustration on the nuclear liquid-gas phase transition. Our conclusions is twofold. First, the range of temperatures where inhomogeneous phases form expands with increasing Coulomb-field strength. Second, within the approximation of uniform electron distribution, the limiting point upon which the phase-coexistence region ends does not exhibit any critical behaviour. Possible astrophysics consequences and thermodynamical connections are discussed.

Napolitani, P; Gulminelli, F; Hasnaoui, K H O; Chomaz, Ph.

2006-01-01

424

Ising analogue to compact-star matter  

E-print Network

By constructing an Ising analogue of compact-star matter at sub-saturation density we explored the effect of Coulomb frustration on the nuclear liquid-gas phase transition. Our conclusions is twofold. First, the range of temperatures where inhomogeneous phases form expands with increasing Coulomb-field strength. Second, within the approximation of uniform electron distribution, the limiting point upon which the phase-coexistence region ends does not exhibit any critical behaviour. Possible astrophysics consequences and thermodynamical connections are discussed.

P. Napolitani; Ph. Chomaz; F. Gulminelli; K. H. O. Hasnaoui

2006-09-22

425

Ising analogue to compact-star matter.  

PubMed

By constructing an Ising analogue of compact-star matter at subsaturation density we explored the effect of Coulomb frustration on the nuclear liquid-gas phase transition. Our conclusion is twofold. First, the range of temperatures where inhomogeneous phases form expands with increasing Coulomb-field strength. Second, within the approximation of uniform electron distribution, the limiting point upon which the phase-coexistence region ends does not exhibit any critical behavior. Possible astrophysics consequences and thermodynamical connections are discussed. PMID:17501178

Napolitani, P; Chomaz, Ph; Gulminelli, F; Hasnaoui, K H O

2007-03-30

426

Disappearance of the negative charge in giant DNA with a folding transition.  

PubMed Central

In the present study we measure the electrophoretic mobility of giant T4 DNA (166 kbp) by electrophoretic light scattering for the elongated and folded compact states at different spermidine (trivalent cation) concentrations in 50 mM sodium maleate buffer (pH 6.0). It is found that the electrophoretic mobility of elongated DNA in the absence of the multivalent cation is seven times greater than that of fully folded compact DNA, where, with the increase of the concentration of spermidine, an abrupt transition is generated after a gradual decrease of the mobility. An analysis of the electrophoretic mobility suggests that the folded compact DNA chains almost completely lose their negative charges, by taking into account the difference of friction mechanism between an elongated and folded compact state. From the single chain observation by use of fluorescence microscopy, it is found that a phase-segregated structure is generated at intermediate concentrations of spermidine. The gradual decrease of the electrophoretic mobility in the transition region is, thus, attributed to the formation of the segregated state, exhibiting partial electroneutralization in the folded part. Disappearance of the negative charges in the completely folded compact DNAs is discussed in relation to the mechanism of transition, in terms of a first-order phase transition. PMID:11371456

Yamasaki, Y; Teramoto, Y; Yoshikawa, K

2001-01-01

427

A compact light concentrator by the use of plasmonic faced folded nano-rods.  

PubMed

We propose a compact nano-metallic structure for enhancing and concentrating far-field transmission: a faced folded nano-rod (FFR) unit, composed of two folded metallic nano-rods placed facing each other in an aperture. By analyzing local charge, field, and current distributions in the FFR unit using three-dimensional finite difference time domain (FDTD) calculation results, we show that although charge and field configurations become somewhat different depending on the polarization states of the illumination, similar current flows are formed in the FFR unit, which entail similar far-field radiation patterns regardless of the polarization states, making the FFR unit a quasi-polarization-insensitive field concentrator. We demonstrate this functionality of the FFR unit experimentally using the holographic microscopy which provides us a three-dimensional map of the complex wavefronts of optical fields emanating from the FFR unit. PMID:21997085

Chung, Taerin; Lim, Yongjun; Lee, Il-Min; Lee, Seoung-Yeol; Choi, Jinyoung; Roh, Sookyoung; Kim, Kyoung-Youm; Lee, Byoungho

2011-10-10

428

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

SciTech Connect

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

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

2014-04-15

429

Compact x-ray source and panel  

DOEpatents

A compact, self-contained x-ray source, and a compact x-ray source panel having a plurality of such x-ray sources arranged in a preferably broad-area pixelized array. Each x-ray source includes an electron source for producing an electron beam, an x-ray conversion target, and a multilayer insulator separating the electron source and the x-ray conversion target from each other. The multi-layer insulator preferably has a cylindrical configuration with a plurality of alternating insulator and conductor layers surrounding an acceleration channel leading from the electron source to the x-ray conversion target. A power source is connected to each x-ray source of the array to produce an accelerating gradient between the electron source and x-ray conversion target in any one or more of the x-ray sources independent of other x-ray sources in the array, so as to accelerate an electron beam towards the x-ray conversion target. The multilayer insulator enables relatively short separation distances between the electron source and the x-ray conversion target so that a thin panel is possible for compactness. This is due to the ability of the plurality of alternating insulator and conductor layers of the multilayer insulators to resist surface flashover when sufficiently high acceleration energies necessary for x-ray generation are supplied by the power source to the x-ray sources.

Sampayon, Stephen E. (Manteca, CA)

2008-02-12

430

Compact high-speed scanning lidar system  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

431

The Evolution of Compact Binary Star Systems  

E-print Network

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

Konstantin Postnov; Lev Yungelson

2014-03-21

432

The Compactness of Presupernova Stellar Cores  

NASA Astrophysics Data System (ADS)

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

Sukhbold, Tuguldur; Woosley, S. E.

2014-03-01

433

Compact dynamical model of brain activity.  

PubMed

A compact physiologically based mean-field formulation of brain dynamics is proposed to model observed brain activity and electroencephalographic (EEG) signals. In contrast to existing formulations, which are more detailed and complicated, our model is described by a single second-order delay differential equation that encapsulates salient aspects of the physiology. The model captures essential features of activity mediated by fast corticocortical connections and delayed feedbacks via extracortical pathways and external stimuli. In the linear regime, these features can be simply expressed by three coefficients derived from the properties of these physiological pathways and explicit nonlinear approximations are also derived. This compact model successfully reproduces the main features of experimental EEG's and the predictions of previous models, including resonance peaks in EEG spectra and nonlinear dynamics. As an illustration, key features of the dynamics of epileptic seizures are shown to be reproduced by the model. Due to its compact form, the model will facilitate insight into nonlinear brain dynamics via standard nonlinear techniques and will guide analysis and investigation of more complex models. It is thus a useful tool for analyzing complex brain activity, especially when it exhibits low-dimensional dynamics. PMID:17500726

Kim, J W; Robinson, P A

2007-03-01

434

Compact dynamical model of brain activity  

NASA Astrophysics Data System (ADS)

A compact physiologically based mean-field formulation of brain dynamics is proposed to model observed brain activity and electroencephalographic (EEG) signals. In contrast to existing formulations, which are more detailed and complicated, our model is described by a single second-order delay differential equation that encapsulates salient aspects of the physiology. The model captures essential features of activity mediated by fast corticocortical connections and delayed feedbacks via extracortical pathways and external stimuli. In the linear regime, these features can be simply expressed by three coefficients derived from the properties of these physiological pathways and explicit nonlinear approximations are also derived. This compact model successfully reproduces the main features of experimental EEG’s and the predictions of previous models, including resonance peaks in EEG spectra and nonlinear dynamics. As an illustration, key features of the dynamics of epileptic seizures are shown to be reproduced by the model. Due to its compact form, the model will facilitate insight into nonlinear brain dynamics via standard nonlinear techniques and will guide analysis and investigation of more complex models. It is thus a useful tool for analyzing complex brain activity, especially when it exhibits low-dimensional dynamics.

Kim, J. W.; Robinson, P. A.

2007-03-01

435

Gated charged-particle trap  

DOEpatents

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

Benner, W. Henry (Danville, CA)

1999-01-01

436

23. 175 TON CAPACITY CHARGING LADLE ON THE CHARGING AISLE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. 175 TON CAPACITY CHARGING LADLE ON THE CHARGING AISLE OF THE BOP SHOP LOOKING SOUTH. HISTORIAN FOR SCALE. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

437

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

SciTech Connect

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

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

2007-07-01

438

Compaction of DNA in an anionic micelle environment followed by assembly into phosphatidylcholine liposomes.  

PubMed

A difficult problem concerning the interaction of DNA with amphiphiles of opposite charge above their critical micelle concentration is the propensity for aggregation of the condensed DNA complexes. In this study, this problem was addressed by attenuating amphiphile charge density within a cholate micelle environment. The amphiphile consisted of a cationic peptide, acetyl-CWKKKPKK-amide, conjugated to dilaurylphos-phatidylethanolamine. In the presence of cholate, multiple equivalents of cationic charge were required to bring about the completion of DNA condensation. At the end point of condensation, stable, soluble DNA-micelle complexes were formed, which by dynamic light scattering exhibited apparent hydro-dynamic diameters between 30 and 60 nm. Aggregation, as measured by static light scattering at 90 degrees and by turbidity, was not observed until further additions of peptide-lipid conjugate were made beyond the end point of DNA condensation. Liposome complexes containing the non-aggregated, compacted DNA were formed by adding dioleoylphosphatidylcholine followed by removing the cholate by dialysis. The resulting complexes were distributed within a narrow density range, the DNA was quantitatively assembled into the liposomes, and liposomes without DNA were not detected. Small particles were formed with a mean hydrodynamic diameter of 77 nm. The liposomal DNA showed complete retention of its supercoiled form and no detectable sensitivity to DNase (25 U/10 microg DNA, 1.5 h, 37 degrees C). The use of an anionic, dialyzable amphiphile to attenuate charge inter-actions between DNA and cationic amphiphiles is a useful technology for the quantitative assembly of compacted DNA into conventional liposomes, with complete protection against nuclease activity. PMID:10908363

Murphy, E A; Waring, A J; Haynes, S M; Longmuir, K J

2000-08-01

439

Compaction of DNA in an anionic micelle environment followed by assembly into phosphatidylcholine liposomes  

PubMed Central

A difficult problem concerning the interaction of DNA with amphiphiles of opposite charge above their critical micelle concentration is the propensity for aggregation of the condensed DNA complexes. In this study, this problem was addressed by attenuating amphiphile charge density within a cholate micelle environment. The amphiphile consisted of a cationic peptide, acetyl-CWKKKPKK-amide, conjugated to dilaurylphosphatidylethanolamine. In the presence of cholate, multiple equivalents of cationic charge were required to bring about the completion of DNA condensation. At the end point of condensation, stable, soluble DNA–micelle complexes were formed, which by dynamic light scattering exhibited apparent hydrodynamic diameters between 30 and 60 nm. Aggregation, as measured by static light scattering at 90° and by turbidity, was not observed until further additions of peptide–lipid conjugate were made beyond the end point of DNA condensation. Liposome complexes containing the non-aggregated, compacted DNA were formed by adding dioleoylphosphatidylcholine followed by removing the cholate by dialysis. The resulting complexes were distributed within a narrow density range, the DNA was quantitatively assembled into the liposomes, and liposomes without DNA were not detected. Small particles were formed with a mean hydrodynamic diameter of 77 nm. The liposomal DNA showed complete retention of its supercoiled form and no detectable sensitivity to DNase (25 U/10 µg DNA, 1.5 h, 37°C). The use of an anionic, dialyzable amphiphile to attenuate charge interactions between DNA and cationic amphiphiles is a useful technology for the quantitative assembly of compacted DNA into conventional liposomes, with complete protection against nuclease activity. PMID:10908363

Murphy, Eric A.; Waring, Alan J.; Haynes, Sherry M.; Longmuir, Kenneth J.

2000-01-01

440

Transverse-structure electrostatic charged particle beam lens  

DOEpatents

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

Moran, M.J.

1998-10-13

441

An electron-beam charge neutralization system for ion implanters  

NASA Astrophysics Data System (ADS)

A new wafer-charge neutralization system which employs a curved solenoid magnetic guiding field and a large-area LaB 6 cathode is described. This system generates a directed beam of low-energy electrons with total current of about 100 mA. The majority of the electrons that impinge on the wafer surface have energies less than 10 eV. This neutralization system is simple and compact, and could be easily incorporated into the existing high-current ion implanters.

Leung, K. N.; Gordon, K. C.; Kunkel, W. B.; McKenna, C. M.; Walther, S. R.; Williams, M. D.

1991-04-01

442

Transverse-structure electrostatic charged particle beam lens  

DOEpatents

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

Moran, Michael J. (Pleasanton, CA)

1998-01-01

443

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

PubMed

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

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

2014-12-18

444

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

NASA Astrophysics Data System (ADS)

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

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

445

Gauss' Law - Point Charge  

NSDL National Science Digital Library

This EJS (Easy Java Simulation) based simulation allows the user to investigate the effects of changing the radius of a Gaussian surface and of changing the charge of a point charge on the flux and electric field along the Gaussian surface. Users may run the simulations by downloading the jar file. A lesson plan and a student study guide are available at the mirror web site. This resource is part of Project ITOP (Improving the Teaching of Physics), a graduate program offered at University of Massachusetts-Boston. The archived computer models are hosted and maintained as part of the BU Physics Simulation collection. The materials in this collection were created with Easy Java Simulations (EJS), a modeling tool that allows users to easily generate modify and share computer models and simulations.

Sweeney, Renee

2011-01-27

446

Approach to casing design for service in compacting reservoirs  

SciTech Connect

Depletion of unconsolidated sand reservoirs can cause compaction of the reservoir sand. This strain transfers load to the casing, and this can kink and crush the casing, preventing workovers and requiring redrilling wells. Early redrilling can have significant negative impact on project earning power, so it is necessary to design casing to withstand compaction loading. This paper explains Shell Oil`s new compaction design philosophy for casing to be run in some highly compactive Gulf of Mexico reservoirs. The paper explains the technical tools used to quantify compaction loading; the relative importance of different casing damage mechanisms; and Shell`s approach to designing casing to mitigate the influence of compaction. Shell`s approach to compaction emphasizes minimizing column buckling under axial compaction loads and collapse under transverse compaction loads. The approach to buckling is based on a model that quantifies the ability to work through buckled casing. The approach to collapse is based on a model linking depletion to the load transferred between the sand, cement, and casing. The compaction solution is specialized to Gulf of Mexico sand and reservoir characteristics. Casing design is only one aspect of the multidisciplinary solution to the compaction problem. Compaction-tolerant sand control must be included in the completion design, and advanced core testing must be used to link the casing design to the stress-strain behavior of unconsolidated sands. Where historical damage exists, downhole casing logging has been used to guide and validate the solution. These other facets of compaction technology go beyond the scope of this paper but have been addressed by Shell Oil`s integrated approach to the compaction problem.

Cernocky, E.P.; Scholibo, F.C.

1995-12-31

447

Battery charge condition monitoring  

Microsoft Academic Search

Basic techniques are presented for determining the charge condition of electric-vehicle propulsion batteries of both the lead--acid and nickel--cadmium types. The techniques presented include those employing measurement of battery parameters, such as electrolyte properties, voltage, and internal resistance, and those utilizing coulometric measurements. An application example employing the coulometric approach is described to demonstrate the usefulness of an accurate battery

Christianson

1974-01-01

448

Wind Power Charged Aerosol Generator  

SciTech Connect

This describes experimental results on a Charged Aerosol Wind/Electric Power Generator, using Induction Electric Charging with a water jet issuing under water pressure from a small diameter (25-100 ..mu..m) orifice.

Marks, A.M.

1980-07-01

449

An Ultra-Compact Marx-Type High-Voltage Generator  

SciTech Connect

This paper discusses the design of an ultra-compact, Marx-type, high-voltage generator. This system incorporates high-performance components that are closely coupled and integrated into an extremely compact assembly. Low profile, custom ceramic capacitors with coplanar extended electrodes provide primary energy storage. Low-inductance, spark-gap switches incorporate miniature gas cavities imbedded within the central region of the annular shaped capacitors, with very thin dielectric sections separating the energy storage capacitors. Carefully shaped electrodes and insulator surfaces are used throughout to minimize field enhancements, reduce fields at triple-point regions, and enable operation at stress levels closer to the intrinsic breakdown limits of the dielectric materials. Specially shaped resistors and inductors are used for charging and isolation during operation. Forward-coupling ceramic capacitors are connected across successive switch-capacitor-switch stages to assist in switching. Pressurized SF, gas is used for electrical insulation in the spark-gap switches and throughout the unit. The pressure housing is constructed entirely of dielectric materials, with segments that interlock with the low-profile switch bodies to provide an integrated support structure for all of the components. This ultra-compact Marx generator employs a modular design that can be sized as needed for a particular application. Units have been assembled with 4, 10, and 30 stages and operated at levels up to 100 kV per stage.

Goerz, D; Ferriera, T; Nelson, D; Speer, R; Wilson, M

2001-06-15

450

Physical Factors Affecting Plasmid DNA Compaction in Stearylamine-Containing Nanoemulsions Intended for Gene Delivery  

PubMed Central

Cationic lipids have been used in the development of non-viral gene delivery systems as lipoplexes. Stearylamine, a cationic lipid that presents a primary amine group when in solution, is able to compact genetic material by electrostatic interactions. In dispersed systems such as nanoemulsions this lipid anchors on the oil/water interface confering a positive charge to them. The aim of this work was to evaluate factors that influence DNA compaction in cationic nanoemulsions containing stearylamine. The influence of the stearylamine incorporation phase (water or oil), time of complexation, and different incubation temperatures were studied. The complexation rate was assessed by electrophoresis migration on agarose gel 0.7%, and nanoemulsion and lipoplex characterization was done by Dynamic Light Scattering (DLS). The results demonstrate that the best DNA compaction process occurs after 120 min of complexation, at low temperature (4 ± 1 °C), and after incorporation of the cationic lipid into the aqueous phase. Although the zeta potential of lipoplexes was lower than the results found for basic nanoemulsions, the granulometry did not change. Moreover, it was demonstrated that lipoplexes are suitable vehicles for gene delivery. PMID:24281666

Silva, André Leandro; Júnior, Francisco Alexandrino; Verissimo, Lourena Mafra; Agnez-Lima, Lucymara Fassarella; Egito, Lucila Carmem Monte; de Oliveira, Anselmo Gomes; do Egito, Eryvaldo Socrates Tabosa

2012-01-01

451

Submerged AUV Charging Station  

NASA Technical Reports Server (NTRS)

Autonomous Underwater Vehicles (AUVs) are becoming increasingly important for military surveillance and mine detection. Most AUVs are battery powered and have limited lifetimes of a few days to a few weeks. This greatly limits the distance that AUVs can travel underwater. Using a series of submerged AUV charging stations, AUVs could travel a limited distance to the next charging station, recharge its batteries, and continue to the next charging station, thus traveling great distances in a relatively short time, similar to the Old West “Pony Express.” One solution is to use temperature differences at various depths in the ocean to produce electricity, which is then stored in a submerged battery. It is preferred to have the upper buoy submerged a reasonable distance below the surface, so as not to be seen from above and not to be inadvertently destroyed by storms or ocean going vessels. In a previous invention, a phase change material (PCM) is melted (expanded) at warm temperatures, for example, 15 °C, and frozen (contracted) at cooler temperatures, for example, 8 °C. Tubes containing the PCM, which could be paraffin such as pentadecane, would be inserted into a container filled with hydraulic oil. When the PCM is melted (expanded), it pushes the oil out into a container that is pressurized to about 3,000 psi (approx equals 20.7 MPa). When a valve is opened, the high-pressure oil passes through a hydraulic motor, which turns a generator and charges a battery. The low-pressure oil is finally reabsorbed into the PCM canister when the PCM tubes are frozen (contracted). Some of the electricity produced could be used to control an external bladder or a motor to the tether line, such that depth cycling is continued for a very long period of time. Alternatively, after the electricity is generated by the hydraulic motor, the exiting low-pressure oil from the hydraulic motor could be vented directly to an external bladder on the AUV, such that filling of the bladder causes the AUV to rise, and emptying of the bladder allows the AUV to descend. This type of direct buoyancy control is much more energy efficient than using electrical pumps in that the inefficiencies of converting thermal energy to electrical energy to mechanical energy is avoided. AUV charging stations have been developed that use electricity produced by waves on floating buoys and that use electricity from solar photovoltaics on floating buoys. This is the first device that has absolutely no floating or visible parts, and is thus impervious to storms, inadvertent ocean vessel collisions, or enemy sabotage.

Jones, Jack A.; Chao, Yi; Curtin, Thomas

2014-01-01

452

PhyzGuide: Electrostatic Charge  

NSDL National Science Digital Library

This article contains some of the history of how electromagnetic theory was developed, along with some very general principles of what we know about static charges. This includes a brief description of types of charges and their properties, what classifies as a conductor or insulator, and how charge is measured.

Baird, Dean

2006-11-18

453

PhyzGuide: Electrostatic Charge  

NSDL National Science Digital Library

From Dean Baird's Book of Phyz, learn the "shocking truths and current models" of electrostatic charge and force, including Ben Franklin's Findings and what we currently know about charge in this two-page PDF document. Helpful illustrations assist learners in better understanding electrostatic charge.

Baird, Dean

2008-05-16

454

The nature of electronic charge  

E-print Network

Advances in gauge theories and unified theories have not thrown light on the meaning of electron. The problem of the origin of electronic charge is made precise, new insights gained from Weyl space are summarized, and the origin of charge in terms of fractional spin is suggested. New perspective on the abelian Chern-Simons theory is presented to explain charge.

S C Tiwari

2006-07-14

455

Perveance and ion bunch structure from a ``compact, high-pressure'' laser ion source  

NASA Astrophysics Data System (ADS)

The Dublin City University (DCU) laser ion source (LIS) is a "compact high-pressure" laser ion source utilizing a table top Q-switched laser. The DCU-LIS combines high laser fluence (F >4 kJ cm-2), high laser intensity (I >1011 W cm-2) with a short field free region (L =48 mm) and high source potential (Vext>40 kV) in order to offset recombination losses within the plasma and maximize the proportion of highly charged ions which are extracted from the plasma plume. Such a configuration also provides high peak currents (Ip>3 mA), high current densities (J >5 mA cm-2), and high charge states (Cu6+) in the extracted ion-bunch train. However, to obtain and utilize these parameter values in a high pressure LIS requires characterization and control of a number of processes related to ion dynamics and space charge effects on the extracted ions at the plasma plume-anode-extraction gap interface. Relevant issues include electric field distortion, Debye shielding, beam divergence, overfocusing, and perveance (P) in addition to current density profiles for the extracted ion beam. In this paper we focus on these issues and their impact on charge particle extraction and acceleration with a view to elucidating the parameter regimes within which the DCU-LIS performance envelope is optimal.

Yeates, P.; Costello, J. T.; Kennedy, E. T.

2010-12-01

456

Charged rotating Kaluza-Klein black holes in dilaton gravity  

SciTech Connect

We obtain a class of slowly rotating charged Kaluza-Klein black hole solutions of the five-dimensional Einstein-Maxwell-dilaton theory with arbitrary dilaton coupling constant. At infinity, the spacetime is effectively four dimensional. In the absence of the squashing function, our solution reduces to the five-dimensional asymptotically flat slowly rotating charged dilaton black hole solution with two equal angular momenta. We calculate the mass, the angular momentum, and the gyromagnetic ratio of these rotating Kaluza-Klein dilaton black holes. It is shown that the dilaton field and the nontrivial asymptotic structure of the solutions modify the gyromagnetic ratio of the black holes. We also find that the gyromagnetic ratio crucially depends on the dilaton coupling constant, {alpha}, and decreases with increasing {alpha} for any size of the compact extra dimension.

Allahverdizadeh, Masoud [Institut fuer Physik, Universitaet Oldenburg, D-26111 Oldenburg (Germany); Matsuno, Ken [Department of Mathematics and Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Sheykhi, Ahmad [Department of Physics, Shahid Bahonar University, Kerman 76175 (Iran, Islamic Republic of)

2010-02-15

457

Development of a compact tomography camera system using a multianode photomultiplier tube for compact torus experiments  

SciTech Connect

A compact tomography camera system consisting of a photomultiplier tube, a multislit optical system, and a band-pass interference filter has been developed. The viewing area and spatial resolution can be configured by the arrangement of the slit system. The camera system has been specially designed for self-organized compact torus experiments having strong magnetohydrodynamics events with a submicrosecond time-scale. The developed system has been tested on a field-reversed configuration formed by the field-reversed theta-pinch. Performance evaluation of the system has been performed by comparison to the former optical system.

Tomuro, H.; Asai, T.; Iguchi, K.; Takahashi, Ts.; Hirano, Y. [Department of Physics, College of Science and Technology, Nihon University, Tokyo 101-8308 (Japan)

2010-10-15

458

A Compact Liquid Xenon Compton Telescope with High Energy Resolution and Time-of-Flight  

NASA Astrophysics Data System (ADS)

Two recent developments have led us to propose a new type of Compton telescope in compact geometry with time-of-flight, for gamma-ray astronomy in the energy regime of 0.2 - 10 MeV. First, the technology of vacuum ultraviolet photosensors for efficient and fast readout of liquid xenon (LXe) scintillation light has improved dramatically over the last few years, and new developments are underway. A LXe Advanced Compton Telescope would consist of two detector arrays of LXe time projection chambers in compact geometry, with time-of-flight (ToF) between detector modules at a resolution of order 100 ps. Second, the previously achieved moderate energy resolution in LXe, a significant draw-back for gamma-ray line spectroscopy, has been found to be largely due to a strong anti-correlation of ionization and scintillation in LXe. Efficient measurement of both charge and light enables us to improve energy resolution greatly. A factor of three improvement over a previous prototype, LXeGRIT, has already been achieved, and the measured underlying physics indicate the possibility of achievng energy resolution below 1% FWHM at 1 MeV. We are vigorously working on improving light and charge readout to realize this potential in a practical detector. We report on the status and prospects of our current research and development program. This work is supported by NASA grant NNG05WC24G.

Oberlack, Uwe; Gomez, R.; Olsen, C.; Shagin, P.; Aprile, E.; Giboni, K.; Plante, G.; Santorelli, R.

2006-09-01

459

Structure and expression of a novel compact myelin protein – Small VCP-interacting protein (SVIP)  

SciTech Connect

Highlights: •SVIP (small p97/VCP-interacting protein) co-localizes with myelin basic protein (MBP) in compact myelin. •We determined that SVIP is an intrinsically disordered protein (IDP). •The helical content of SVIP increases dramatically during its interaction with negatively charged lipid membrane. •This study provides structural insight into interactions between SVIP and myelin membranes. -- Abstract: SVIP (small p97/VCP-interacting protein) was initially identified as one of many cofactors regulating the valosin containing protein (VCP), an AAA+ ATPase involved in endoplasmic-reticulum-associated protein degradation (ERAD). Our previous study showed that SVIP is expressed exclusively in the nervous system. In the present study, SVIP and VCP were seen to be co-localized in neuronal cell bodies. Interestingly, we also observed that SVIP co-localizes with myelin basic protein (MBP) in compact myelin, where VCP was absent. Furthermore, using nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopic measurements, we determined that SVIP is an intrinsically disordered protein (IDP). However, upon binding to the surface of membranes containing a net negative charge, the helical content of SVIP increases dramatically. These findings provide structural insight into interactions between SVIP and myelin membranes.

Wu, Jiawen [Department of Neurology, Vanderbilt University School of Medicine (United States)] [Department of Neurology, Vanderbilt University School of Medicine (United States); Peng, Dungeng [Department of Biochemistry, Vanderbilt University School of Medicine (United States)] [Department of Biochemistry, Vanderbilt University School of Medicine (United States); Voehler, Markus [Center for Structural Biology, Vanderbilt University (United States)] [Center for Structural Biology, Vanderbilt University (United States); Sanders, Charles R. [Department of Biochemistry, Vanderbilt University School of Medicine (United States) [Department of Biochemistry, Vanderbilt University School of Medicine (United States); Center for Structural Biology, Vanderbilt University (United States); Li, Jun, E-mail: jun.li.2@vanderbilt.edu [Department of Neurology, Vanderbilt University School of Medicine (United States) [Department of Neurology, Vanderbilt University School of Medicine (United States); Tennessee Valley Healthcare System (TVHS) – Nashville VA (United States)

2013-10-11

460

Geoengineering with Charged Droplets  

NASA Astrophysics Data System (ADS)

Water molecules in a droplet are held together by intermolecular forces generated by hydrogen bonding which has a bonding energy of only about 0.2 eV. One can create a more rugged droplet by using an ion as a condensation nucleus. In that case, water molecules are held together by the interaction between the ion and the dipole moments of the water molecules surrounding the ion, in addition to any hydrogen bonding. In this research, properties of such charged droplets were investigated using first principle quantum mechanical calculations. A molecule which exhibits positive electron affinity is a good candidate to serve as the ionic condensation nucleus, because addition of an electron to such a molecule creates an energetically more stable state than the neutral molecule. A good example is the oxygen molecule (O2) where energy of O2 negative (O2-) ion is lower than that of the neutral O2 by about 0.5 eV. Examples of other molecules which have positive electron affinity include ozone (O3), nitrogen dioxide (NO2) and sulfur oxides (SOx, x=1-3). Atomic models used in the calculations consisted of a negative ion of one of the molecules mentioned above surrounded by water molecules. Calculations were performed using the DFT method with B3LYP hybrid functional and Pople type basis sets with polarization and diffuse functions. Energy of interaction between O2- ion and the water molecule was found to be ~0.7 eV. This energy is an order of magnitude greater than the thermal energy of even the highest temperatures encountered in the atmosphere. Once created, charged rugged droplets can survive in hot and dry climates where they can be utilized to create humidity and precipitation. The ion which serves as the nucleus of the droplet can attract not only water molecules but also other dipolar gases in the atmosphere. Such dipolar gases include industrial pollutants, for example nitrogen dioxide (NO2) or sulfur dioxide (SO2). Energy of interaction between O2- ion and pollutant molecules was calculated to be ~0.5 eV for NO2 and ~0.9 eV for SO2. These values are comparable to that of water, hence charged droplets have the potential to serve as scavengers of pollutants in the atmosphere. The charged droplet can also interact with quadrupolar gases depending on the charge distribution of the gas. A quadrupole of interest is carbon dioxide (CO2) where oxygens are slightly negative and carbon is slightly positive in a neutral molecule. When CO2 is in the vicinity of a negative ion, the carbon atom gets attracted to the ion, whereas oxygens are repelled from it. This interaction distorts the linear geometry of CO2, turning it into a small dipole. Energy of interaction between O2- ion and CO2 was calculated to be ~0.3 eV which is smaller than those of the above mentioned dipoles, but still significantly greater than the typical thermal energy at 25 C (~0.03 eV). One can expect the diffusion of atmospheric CO2 into the droplets to be enhanced due to the charge. Hence such droplets can help capture the CO2 in the atmosphere and sequester it simply as rain. Charged droplets can be created using electrical,optical, thermal or other means. A method which utilizes solar energy will be described in the presentation.

Gokturk, H.

2011-12-01

461

Compact quantum dots for single-molecule imaging.  

PubMed

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology (1-4). To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study. Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation (5). Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large (4,6,7). Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past (8,9). The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm). PMID:23093375

Smith, Andrew M; Nie, Shuming

2012-01-01

462

CYANATE ION IN COMPACT AMORPHOUS WATER ICE  

SciTech Connect

The 4.62 {mu}m infrared (2164.5 cm{sup -1}) absorption band, observed in ice mantels toward many young stellar objects, has been mostly attributed to the {nu}{sub 3} (CN stretch) band of OCN{sup -} ions. We present in this work a spectroscopic study of OCN{sup -} ions embedded in compact amorphous ice in a range of concentrations and temperatures relevant to astronomical observations together with quantum mechanical calculations of the {nu}{sub 3} band of OCN{sup -} in various H{sub 2}O environments. The ice samples containing the ions are prepared through hyperquenching of liquid droplets of K{sup +}OCN{sup -} solutions on a substrate at 14 K. The {nu}{sub 3} OCN{sup -} band appears as a broad feature peaking at 4.64 {mu}m with a secondary maximum at 4.54 {mu}m and is much weaker than the corresponding peak in the liquid solution or in the solid salt. A similar weakening is observed for other OCN{sup -} absorption peaks at 7.66 {mu}m (2{nu}{sub 2}) and 8.20 {mu}m ({nu}{sub 1}). The theoretical calculations for the {nu}{sub 3} vibration lead to a range of frequencies spanning the experimentally observed width. This frequency spread could help explain the pronounced drop in the band intensity in the ice. The OCN{sup -} {nu}{sub 3} band in the present compact ices is also broader and much weaker than that reported in the literature for OCN{sup -} ions obtained by variously processing porous ice samples containing suitable neutral precursors. The results of this study indicate that the astronomical detection of OCN{sup -} in ice mantels could be significantly impaired if the ion is embedded in a compact water network.

Mate, Belen; Herrero, Victor J.; Rodriguez-Lazcano, Yamilet; Moreno, Miguel A.; Escribano, Rafael [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, E-28006 Madrid (Spain); Fernandez-Torre, Delia [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28050 Madrid (Spain); Gomez, Pedro C. [Departamento de Quimica Fisica I, Universidad Complutense, Unidad Asociada UCM-CSIC, E-28040 Madrid (Spain)

2012-11-10

463

Raytheon's next generation compact inline cryocooler architecture  

NASA Astrophysics Data System (ADS)

Infrared sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection has become application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive infrared (IR) sensors, the Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage and 2-stage cold-head architectures with an inventive set of warm-end mechanisms into a single mechanical module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (<20% improvement) and exported vibration performance (<=25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.

Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

2013-09-01

464

Compact proton spectrometers for measurements of shock  

SciTech Connect

The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign (NIC) diagnostic. The WRF measures the spectrum of protons from D-{sup 3}He reactions in tuning-campaign implosions containing D and {sup 3}He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total {rho}R through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

Mackinnon, A; Zylstra, A; Frenje, J A; Seguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M G; Casey, D T; Sinenian, N; Manuel, M; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G; Dewald, E; Doeppner, T; Edwards, M J; Glenzer, S H; Hicks, D; Landen, O L; London, R; Meezan, N B

2012-05-02

465

Overview of the Compact Ignition tokamak  

SciTech Connect

The Compact Ignition Tokamak (CIT) mission is to achieve ignition and provide the capability to experimentally study burning plasma behavior. A national team has developed a baseline concept including definition of the necessary research and development. The baseline concept satisfies the physics performance objectives established for the project and complies with defined design specifications. To ensure that the mission is achieved, the design requires large magnetic fields on axis (10 T) and use of large plasma currents (10 MA). The design is capable of accommodating significant auxiliary heating to enter the ignited regime. The CIT is designed to operate in plasma parameter regimes that a are directly relevant to future fusion power reactors.

Flanagan, C. A. [Westinghouse Electric Company, Cranberry Township, PA; Peng, Yueng Kay Martin [ORNL

1986-01-01

466

Eccentric Motion of Spinning Compact Binaries  

E-print Network

The equations of motion for spinning compact binaries on eccentric orbits are treated perturbatively in powers of a fractional mass-difference ordering parameter. The solution is valid through first order in the mass-difference parameter. A canonical point transformation removes the leading order terms of the spin-orbit Hamiltonian which induce a wiggling precession of the orbital angular momentum around the conserved total angular momentum, a precession which disappears in the case of equal masses or one single spin. Action-angle variables are applied which make a canonical perturbation theory easily treatable.

Manuel Tessmer; Gerhard Schäfer

2014-06-02

467

Controlled microbubble generation on a compact disk  

NASA Astrophysics Data System (ADS)

We develop a rotationally actuated fluidic device for controlled generation of microbubbles in a lab-on-a-compact-disk based environment. Use of such a strategy essentially implicates that one may employ simplistic, versatile, flexible, and economized microfabrication as well as fluidic actuation techniques, instead of more complex traditional methodologies, for microbubble generation and control. We further demonstrate that the spatio-temporal frequencies and size distributions of the generated bubbles may be judiciously controlled by simply tailoring the rotational speeds, corresponding to given channel dimensions and fluid-substrate combinations.

Chakraborty, Debapriya; Chakraborty, Suman

2010-12-01

468

Gamma rays from compact binary system  

E-print Network

Some of the very high energy (VHE) gamma-ray sources detected with the modern generation of Cherenkov telescopes have been identified with previously known X-ray binary systems. These detections demonstrate the richness of non-thermal phenomena in compact galactic objects containing relativistic outflows or winds produced near black holes and neutron stars. Recently, the well-known microquasar Cygnus X-3 seems to be associated with a gamma-ray source detected with AGILE. Here I summarise the main observational results on gamma-ray emission from X-ray binaries, as well as some of the proposed scenarios to explain the production of VHE gamma-rays.

Josep M. Paredes

2008-10-24

469

Found: High Surface Brightness Compact Galaxies  

E-print Network

We are using the 2dF spectrograph to make a survey of all objects (`stars' and `galaxies') in a 12 sq.deg region towards the Fornax cluster. We have discovered a population of compact emission-line galaxies unresolved on photographic sky survey plates and therefore missing in most galaxy surveys based on such material. These galaxies are as luminous as normal field galaxies. Using H-alpha to estimate star formation they contribute at least an additional 5 per cent to the local star formation rate.

M. J. Drinkwater; S. Phillipps; J. B. Jones; M. D. Gregg; Q. A. Parker; R. M. Smith; J. I. Davies; E. M. Sadler

1998-10-20

470

Raytheon's next generation compact inline cryocooler architecture  

SciTech Connect

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (?25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.

Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T. [Raytheon Space and Airborne Systems, 2000 E. El Segundo Blvd., El Segundo, CA 90245 (United States)

2014-01-29

471

Casimir Forces between Arbitrary Compact Objects  

SciTech Connect

We develop an exact method for computing the Casimir energy between arbitrary compact objects, either dielectrics or perfect conductors. The energy is obtained as an interaction between multipoles, generated by quantum current fluctuations. The objects' shape and composition enter only through their scattering matrices. The result is exact when all multipoles are included, and converges rapidly. A low frequency expansion yields the energy as a series in the ratio of the objects' size to their separation. As an example, we obtain this series for two dielectric spheres and the full interaction at all separations for perfectly conducting spheres.

Emig, T. [Laboratoire de Physique Theorique et Modeles Statistiques, CNRS UMR 8626, Universite Paris-Sud, 91405 Orsay (France); Graham, N. [Department of Physics, Middlebury College, Middlebury, Vermont 05753 (United States); Center for Theoretical Physics, Laboratory for Nuclear Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Jaffe, R. L. [Center for Theoretical Physics, Laboratory for Nuclear Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Kardar, M. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2007-10-26

472

Dynamic Hysteresis in Compacted Magnetic Nanoparticles  

NASA Astrophysics Data System (ADS)

The frequency and temperature dependent magnetic response of a bulk soft magnetic nanocomposite made by compacting Fe10Co 90 nanoparticles was measured and modeled. Electron microscopy and x-ray diffraction were used to characterize the size, composition, and structure of the nanoparticles and nanocomposite. Polyol synthesis was used to produce 200 nm particles with average grain size 20 nm and large superparamagnetic fraction. The nanoparticles were consolidated to 90% theoretical density by plasma pressure compaction. The compacted nanoparticles retained the 20 nm average grain size and large superparamagnetic fraction. The nanocomposite resistivity was more than three times that of the bulk alloy. Vibrating sample and SQUID-MPMS magnetometers were used for low frequency magnetic measurements of the nanoparticles and nanocomposite. Compaction reduced the coercivity from 175 Oe to 8 Oe and the effective anisotropy from 124 x 10 3 ergs/cc to 7.9 x 103 ergs/cc. These reductions were caused by increased exchange coupling between surface nanograins, consistent with predictions from the Random Anisotropy model. Varying degrees of exchange coupling existed within the nanocomposite, contributing to a distribution of energy barriers. A permeameter was used for frequency dependent magnetic measurements on a toroid cut from the nanocomposite. Complex permeability, coercivity, and power loss were extracted from dynamic minor hysteresis loops measured over a range of temperatures (77 K - 873 K) and frequencies (0.1 kHz - 100 kHz). The real and imaginary parts of the complex permeability spectrum showed asymmetries consistent with a distribution of energy barriers and high damping. When the complex permeability, power loss, and coercivity were scaled relative to the peak frequency of the imaginary permeability, all fell on universal curves. Various microscopic and macroscopic models for the complex permeability were investigated. The complex permeability was successfully fit by modifying the Cole-Davidson model with a scaling factor that extended the model to higher damping. The additional damping was consistent with the damping from eddy current modeling, showing that the nanocomposite's complex permeability could be explained by combining microscopic effects (the distribution of energy barriers represented by the Cole-Davidson model) with macroscopic effects (damping due to eddy currents).

Chowdary, Krishna M.

473

Compact Plasma Accelerator for Micropropulsion Applications  

NASA Technical Reports Server (NTRS)

There is a need for a low power, light-weight (compact), high specific impulse electric propulsion device to satisfy mission requirements for microsatellite (1 to 20 kg) class missions. Satisfying these requirements entails addressing the general problem of generating a sufficiently dense plasma within a relatively small volume and then accelerating it. In the work presented here, the feasibility of utilizing a magnetic cusp to generate a dense plasma over small length scales of order 1 mm is investigated. This approach could potentially mitigate scaling issues associated with conventional ion thruster plasma containment schemes. Plume and discharge characteristics were documented using a Faraday probe and a retarding potential analyzer.

Foster, John E.

2001-01-01

474

Raytheon's next generation compact inline cryocooler architecture  

NASA Astrophysics Data System (ADS)

Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (?25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing techniques and hardware can be utilized to null all motion along the common axis. Low vibration translates to better sensor performance resulting in simpler, more direct mechanical mounting configurations, eliminating the need for convoluted, expensive, massive, long lead damping hardware.

Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

2014-01-01

475

Compact Imaging Spectrometer Utilizing Immersed Gratings  

DOEpatents

A compact imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The imaging spectrometer comprises an entrance slit for transmitting light, a system for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the system for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the system for receiving the light and the system for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light through an optical element to the detector array.

Chrisp, Michael P. (Danville, CA); Lerner, Scott A. (Corvallis, OR); Kuzmenko, Paul J. (Livermore, CA); Bennett, Charles L. (Livermore, CA)

2006-03-21

476

Fractional charges and Misner-Wheeler charge without charge effect in metamaterials  

E-print Network

Optical space in metamaterials may be engineered to emulate four dimensional Kaluza-Klein theory. Nonlinear optics of such metamaterials mimics interaction of quantized electric charges. An electromagnetic wormhole is designed, which connects two points of such an optical space and changes its effective topology. Electromagnetic field configurations which exhibit fractional charges appear as a result of such topology change. Moreover, such effects as Misner-Wheeler charge without charge may be replicated.

Igor I. Smolyaninov

2014-12-08

477

Sewerage service charges  

E-print Network

that such terms as " sewer rental" and "sewer tax? have been widely used to designate a charge for sewerage service. The use of such terms has resulted in much confusion and misunderstanding. The average person thinks of the term "rental" as a payment by him... for the privilege of oc? cupying or using the property which belongs to someone else. He cannot see why he should pay a rental for the use of the sewerage system which is owned by the city and paid for from tax money# The word "tax" conveys to the average...

Wright, Samuel Robert

1946-01-01

478

A study of compaction bands originating from cracks, notches, and compacted defects  

E-print Network

spontaneously in high porosity rock under certain compressive stress conditions. Recent experiments show, occurring in initially high porosity rocks subjected to high mean and low differential compressive stress that compaction bands may nucleate at the edges of notches, holes and cracks subjected to compressive stress. We

Einat, Aharonov

479

Relating Follicly-Challenged Compact Stars to Bald Black Holes  

E-print Network

Compact stars satisfy certain no-hair relations through which their multipole moments are given by their mass, spin and quadrupole moment. These relations are approximately independent of their equation of state, relating pressure to density. Such relations are similar to the black hole no-hair theorems, but these possess event horizons inside which information that led to their formation can hide. Compact stars do not possess horizons, so whether their no-hair relations are related to the black hole ones is unclear. We here show numerically that the compact star no-hair relations approach the black hole ones as the compactness approaches that of a black hole. We moreover show that compact stars become progressively oblate in this limit, even if prolate at low compactness due to strong anisotropies.

Yagi, Kent

2015-01-01

480

Chromatin Compaction Protects Genomic DNA from Radiation Damage  

PubMed Central

Genomic DNA is organized three-dimensionally in the nucleus, and is thought to form compact chromatin domains. Although chromatin compaction is known to be essential for mitosis, whether it confers other advantages, particularly in interphase cells, remains unknown. Here, we report that chromatin compaction protects genomic DNA from radiation damage. Using a newly developed solid-phase system, we found that the frequency of double-strand breaks (DSBs) in compact chromatin after ionizing irradiation was 5–50-fold lower than in decondensed chromatin. Since radical scavengers inhibited DSB induction in decondensed chromatin, condensed chromatin had a lower level of reactive radical generation after ionizing irradiation. We also found that chromatin compaction protects DNA from attack by chemical agents. Our findings suggest that genomic DNA compaction plays an important role in maintaining genomic integrity. PMID:24130727

Takata, Hideaki; Hanafusa, Tomo; Mori, Toshiaki; Shimura, Mari; Iida, Yutaka; Ishikawa, Kenichi; Yoshikawa, Kenichi; Yoshikawa, Yuko; Maeshima, Kazuhiro

2013-01-01