Charged polytropic compact stars
Subharthi Ray; Manuel Malheiro; Jose' P. S. Lemos; Vilson T Zanchin
2004-03-19
In this work, we analyze the effect of charge in compact stars considering the limit of the maximum amount of charge they can hold. We find that the global balance of the forces allows a huge charge (~ 10^{20} Coulomb) to be present in a neutron star producing a very high electric field (~ 10^{21} V/m). We have studied the particular case of a polytropic equation of state and assumed that the charge distribution is proportional to the mass density. The charged stars have large mass and radius as we should expect due to the effect of the repulsive Coulomb force with the M/R ratio increasing with charge. In the limit of the maximum charge the mass goes up to ~ 10 M_sun which is much higher than the maximum mass allowed for a neutral compact star. However, the local effect of the forces experienced by a single charged particle, makes it to discharge quickly. This creates a global force imbalance and the system collapses to a charged black hole.
Gravito-electrostatic fluctuations of a polytropic charged dust cloud
NASA Astrophysics Data System (ADS)
Gohain, M.; Karmakar, P. K.
2014-12-01
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.
Charged Polytropic Stars and a Generalization of Lane-Emden Equation
Rodrigo Picanco; Manuel Malheiro; Subharthi Ray
2004-02-12
In this paper we will discuss charged stars with polytropic equation of state, where we will try to derive an equation analogous to the Lane-Emden equation. We will assume that these stars are spherically symmetric, and the electric field have only the radial component. First we will review the field equations for such stars and then we will proceed with the analog of the Lane-Emden equation for a polytropic Newtonian fluid and their relativistic equivalent. These kind of equations are very interesting because they transform all the structure equations of the stars in a group of differential equations which are much more simple to solve than the source equations. These equations can be solved numerically for some boundary conditions and for some initial parameters. For this we will assume that the pressure caused by the electric field obeys a polytropic equation of state too.
Electrically charged compact stars and formation of charged black holes
Subharthi Ray; Aquino L. Espindola; Manuel Malheiro; Jose' P. S. Lemos; Vilson T. Zanchin
2003-08-19
We study the effect of electric charge in compact stars assuming that the charge distribution is proportional to the mass density. The pressure and the density of the matter inside the stars are large, and the gravitational field is intense. This indicates that electric charge and a strong electric field can also be present. The relativistic hydrostatic equilibrium equation, i.e., the Tolman-Oppenheimer-Volkoff equation, is modified in order to include electric charge. We perform a detailed numerical study of the effect of electric charge using a polytropic equation of state. We conclude that in order to see any appreciable effect on the phenomenology of the compact stars, the electric fields have to be huge (~ 10^{21} V/m), which implies that the total charge is Q ~ 10^{20} Coulomb. From the local effect of the forces experienced on a single charged particle, it is expected that each individual charged particle is quickly ejected from the star. This in turn produces a huge force imbalance, and the gravitational force overwhelms the repulsive Coulomb and fluid pressure forces. The star can then collapse to form a charged black hole before all the charge leaves the system.
Electrically charged compact stars
Subharthi Ray; Manuel Malheiro; Jose' P. S. Lemos; Vilson T. Zanchin
2006-04-17
We review here the classical argument used to justify the electrical neutrality of stars and show that if the pressure and density of the matter and gravitational field inside the star are large, then a charge and a strong electric field can be present. For a neutron star with high pressure (~ 10^{33} to 10^{35} dynes /cm^2) and strong gravitational field (~ 10^{14} cm/s^2), these conditions are satisfied. The hydrostatic equation which arises from general relativity, is modified considerably to meet the requirements of the inclusion of the charge. In order to see any appreciable effect on the phenomenology of the neutron stars, the charge and the electrical fields have to be huge (~ 10^{21} Volts/cm). These stars are not however stable from the viewpoint that each charged particle is unbound to the uncharged particles, and thus the system collapses one step further to a charged black hole
Marcelo Gleiser; Damian Sowinski
2013-11-13
Spatially-bound objects across diverse length and energy scales are characterized by a binding energy. We propose that their spatial structure is mathematically encoded as information in their momentum modes and described by a measure known as configurational entropy (CE). Investigating solitonic Q-balls and stars with a polytropic equation of state $P = K{\\rho}^{\\gamma}$, we show that objects with large binding energy have low CE, whereas those at the brink of instability (zero binding energy) have near maximal CE. In particular, we use the CE to find the critical charge allowing for classically stable Q-balls and the Chandrasekhar limit for white dwarfs $({\\gamma} = 4/3)$ with an accuracy of a few percent.
Spherically symmetric charged compact stars
NASA Astrophysics Data System (ADS)
Maurya, S. K.; Gupta, Y. K.; Ray, Saibal; Chowdhury, Sourav Roy
2015-08-01
In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein-Maxwell field equations we take into account the presence of ordinary baryonic matter together with the electric charge. Specific new charged stellar models are obtained where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We systematically analyze altogether the three sets of Solutions I, II, and III of the stellar models for a suitable functional relation of . However, it is observed that only the Solution I provides a physically valid and well-behaved situation, whereas the Solutions II and III are not well behaved and hence not included in the study. Thereafter it is exclusively shown that the Solution I can pass through several standard physical tests performed by us. To validate the solution set presented here a comparison has also been made with that of the compact stars, like , , , , and , and we have shown the feasibility of the models.
Charged compact objects in the linear regime
P. Mafa Takisa; S. Ray; S. D. Maharaj
2014-12-28
Astrophysical compact stars provide a natural laboratory for testing theoretical models which are otherwise difficult to prove from an experimental setup. In our present work we analyse an exact solution to the Einstein-Maxwell system for a charged anisotropic compact body in the linear regime. The charged parameter may be set to zero which gives us the case of neutral solutions. We have tuned the model parameters for the uncharged case so as to match with recent updated mass-radius estimates for five different compact objects. Then we make a systematic study of the effect of charge for the different parameter set that fits the observed stars. The effect of charge is clearly illustrated in the increase of mass. We show that the physical quantities for the objects PSR J1614-2230, PSR J1903+327, Vela X-1, SMC X-1, Cen X-3 are well behaved.
Newtonian and relativistic polytropes
Araujo, F M
2011-01-01
The equation of state inside very compact objects like neutron stars is still largely unkown. Even though a lot progress has been made in recent years to develop the so-called realistic equations of state, a lot of insight can be gained by using polytropic equations of state to integrate the stellar equations of structure. In this work we provide a brief review of the Newtonian and relativistic equations of structure and present some numerical results, which we believe that can be useful for students starting to work on this field. The internal structure of the Newtonian polytropes is obtained by the numerical integration of the Lane-Emden equation, and we used our results which can also be used to study the Chandrasekhar limit for white dwarfs. However, Newtonian physics cannot correctly describe very compact and massive objects. There is an upper mass limit for neutron stars, supported by observations, which is not predicted by the Newtonian equations. Neutron stars are best described under the framework of...
Newtonian and relativistic polytropes
F. M. Araujo; C. B. M. H. Chirenti
2011-02-11
The equation of state inside very compact objects like neutron stars is still largely unkown. Even though a lot progress has been made in recent years to develop the so-called realistic equations of state, a lot of insight can be gained by using polytropic equations of state to integrate the stellar equations of structure. In this work we provide a brief review of the Newtonian and relativistic equations of structure and present some numerical results, which we believe that can be useful for students starting to work on this field. The internal structure of the Newtonian polytropes is obtained by the numerical integration of the Lane-Emden equation, and we used our results which can also be used to study the Chandrasekhar limit for white dwarfs. However, Newtonian physics cannot correctly describe very compact and massive objects. There is an upper mass limit for neutron stars, supported by observations, which is not predicted by the Newtonian equations. Neutron stars are best described under the framework of General Relativity. The introduction of the TOV equations (as well as the relativistic Lane-Emden equations) is, therefore, necessary to correctly identify stable and non-stable models via the mass-radius relation. The analysis of the EoS also becomes relevant to discard models that allow a possible violation of causality (sound speed larger than c).
NASA Technical Reports Server (NTRS)
Barnes, A.; Boss, A. P.
1984-01-01
An extremely massive unevolved star may be idealized as an n = 3 polytropic sphere supported by radiation pressure. Such a polytrope is subject to explosive, supersonic expansion, whose later stages can be described by similarity solution of the dynamical equations. This picture is confirmed by numerical hydrodynamic simulation, which shows that an n = 3 polytrope, initially at rest near equilibrium, undergoes an explosive expansion which approaches the similarity solution at large times.
Spherical polytropic balls cannot mimic black holes
Hiromi Saida; Atsuhito Fujisawa; Chul-Moon Yoo; Yasusada Nambu
2015-03-09
The so-called black hole shadow is a dark region which is expected to appear in a fine image of optical observation of black holes. It is essentially an absorption cross section of black hole, and the boundary of shadow is determined by unstable circular orbits of photons (UCOP). If there exists a compact object possessing UCOP but no black hole horizon, it can provide us with the same shadow image with black holes, and a detection of shadow image cannot be a direct evidence of black hole existence. However, we show that a static spherical polytropic ball of perfect fluid cannot possess UCOP, if the sound speed at centre is subluminal (slower-than-light). This implies that, if the polytrope is a good model of stellar matter in compact objects, a detection of shadow image is regarded as a good evidence of black hole existence. As a by-product, we have found an upper bound of mass-to-radius radio of polytropic ball, $M/R < 0.281$, under the subluminal sound speed condition.
Polytropic process and tropical Cyclones
Romanelli, Alejandro; Rodríguez, Juan
2013-01-01
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.
Conformally flat polytropes for anisotropic matter
L. Herrera; A. Di Prisco; W. Barreto; J. Ospino
2014-11-05
We analyze in detail conformally flat spherically symmetric fluid distributions, satisfying a polytropic equation of state. Among the two possible families of relativistic polytropes, only one contains models which satisfy all the required physical conditions. The ensuing configurations are necessarily anisotropic and show interesting physical properties. Prospective applications of the presented models to the study of super-Chandrasekhar white dwarfs, are discussed.
Inversion charge linearization in MOSFET modeling and rigorous derivation of the EKV compact model
NASA Astrophysics Data System (ADS)
Sallese, Jean-Michel; Bucher, Matthias; Krummenacher, François; Fazan, Pierre
2003-04-01
In this paper, the implications of inversion charge linearization in compact MOS transistor modeling are discussed. The charge-sheet model provides the basic relation among inversion charge and applied potentials, via the implicit surface potential. A rigorous derivation of simpler relations among inversion charge and applied external potentials is provided, using the technique of inversion charge linearization versus surface potential. The new concept of the pinch-off surface potential and a new definition of the inversion charge linearization factor are introduced. In particular, we show that the EKV charge-based model can be considered as an approximation to the more general approach presented here. An improvement to the EKV charge-based model is proposed in the form of a more accurate charge-voltage relationship. This model is analyzed in detail and shows an excellent agreement with the charge sheet model. The normalization of voltages, current and charges, as motivated by the inversion charge linearization, results in a major simplification in compact modeling in static as well as non-quasi-static derivations.
A Compact Wireless Charging System for Electric Vehicles
Ning, Puqi [ORNL] [ORNL; Miller, John M [ORNL] [ORNL; Onar, Omer C [ORNL] [ORNL; White, Cliff P [ORNL] [ORNL
2013-01-01
In this paper, a compact high efficiency wireless power transfer system has been designed and developed. The detailed gate drive design, cooling system design, power stage development, and system assembling are presented. The successful tests verified the feasibility of wireless power transfer system to achieve over-all 90% efficiency.
Vibrational Stability of Differentially Rotating Polytropic Stars
NASA Astrophysics Data System (ADS)
Kumar, Sunil; Lal, A. K.; Saini, Seema
2015-03-01
A method for computing the periods of radial and non-radial modes of oscillations to determine the vibrational stability of differentially rotating polytropic gaseous spheres is presented and incorporated with averaging techniques of Kippenhahn and Thomas. The concepts of Roche-equipotential have also been used for obtaining the distorted structure of different stellar models. Numerical results based on this study are presented to explain the effect of differential rotation on the oscillations and stability of polytropic stars.
String winding modes from charge non-conservation in compact Chern-Simons theory
Leith Cooper; Ian I. Kogan; Lee Kai-Ming
1997-01-01
In this letter we show how string winding modes can be constructed using topological membranes. We use the fact that monopole-instantons in compact topologically massive gauge theory lead to charge non-conservation inside the membrane which, in turn, enables us to construct string vertex operators with different left and right momenta. The amount of charge non-conservation inside the membrane is interpreted
Charges and Fluxes in Maxwell Theory on Compact Manifolds with Boundary
Marcos Alvarez; David I. Olive
2006-01-01
We investigate the charges and fluxes that can occur in higher-order Abelian gauge theories defined on compact space-time manifolds with boundary. The boundary is necessary to supply a destination to the electric lines of force emanating from brane sources, thus allowing non-zero net electric charges, but it also introduces new types of electric and magnetic flux. The resulting structure of
Low power, compact charge coupled device signal processing system
NASA Technical Reports Server (NTRS)
Bosshart, P. W.; Buss, D. D.; Eversole, W. L.; Hewes, C. R.; Mayer, D. J.
1980-01-01
A variety of charged coupled devices (CCDs) for performing programmable correlation for preprocessing environmental sensor data preparatory to its transmission to the ground were developed. A total of two separate ICs were developed and a third was evaluated. The first IC was a CCD chirp z transform IC capable of performing a 32 point DFT at frequencies to 1 MHz. All on chip circuitry operated as designed with the exception of the limited dynamic range caused by a fixed pattern noise due to interactions between the digital and analog circuits. The second IC developed was a 64 stage CCD analog/analog correlator for performing time domain correlation. Multiplier errors were found to be less than 1 percent at designed signal levels and less than 0.3 percent at the measured smaller levels. A prototype IC for performing time domain correlation was also evaluated.
A compact, high-voltage pulsed charging system based on an air-core pulse transformer
NASA Astrophysics Data System (ADS)
Zhang, Tianyang; Chen, Dongqun; Liu, Jinliang; Liu, Chebo; Yin, Yi
2015-09-01
Charging systems of pulsed power generators on mobile platforms are expected to be compact and provide high pulsed power, high voltage output, and high repetition rate. In this paper, a high-voltage pulsed charging system with the aforementioned characteristics is introduced, which can be applied to charge a high-voltage load capacitor. The operating principle of the system and the technical details of the components in the system are described in this paper. The experimental results show that a 600 nF load capacitor can be charged to 60 kV at 10 Hz by the high-voltage pulsed charging system for a burst of 0.5 s. The weight and volume of the system are 60 kg and 600 × 500 × 380 mm3, respectively.
Quasinormal modes of the polytropic hydrodynamic vortex
NASA Astrophysics Data System (ADS)
Oliveira, Leandro A.; Cardoso, Vitor; Crispino, Luís C. B.
2015-07-01
Analogue systems are a powerful instrument to investigate and understand in a controlled setting many general-relativistic effects. Here, we focus on superradiant-triggered instabilities and quasinormal modes. We consider a compressible hydrodynamic vortex characterized by a polytropic equation of state, the polytropic hydrodynamic vortex, a purely circulating system with an ergoregion but no event horizon. We compute the quasinormal modes of this system numerically with different methods, finding excellent agreement between them. When the fluid velocity is larger than the speed of sound, an ergoregion appears in the effective spacetime, triggering an "ergoregion instability." We study the details of the instability for the polytropic vortex, and in particular find analytic expressions for the marginally stable configuration.
Thermodynamic behavior and stability of Polytropic gas
H. Moradpour; A. Abri; H. Ebadi
2015-07-10
We focus on the thermodynamic behavior of Polytropic gas as a candidate for dark energy. We use the general arguments of thermodynamics to investigate its properties and behavior. We find that a Polytropic gas may exhibit the dark energy like behavior in the large volume and low temperature limits. It also may be used to simulate a fluid with zero pressure at the small volume and high temperature limits. Briefly, our study shows that this gas may be used to describe the universe expansion history from the matter dominated era to the current accelerating era. By applying some initial condition to the system, we can establish a relation between the Polytropic gas parameters and initial conditions. Relationships with related works has also been addressed.
Thermodynamic behavior and stability of Polytropic gas
Moradpour, H; Ebadi, H
2015-01-01
We focus on the thermodynamic behavior of Polytropic gas as a candidate for dark energy. We use the general arguments of thermodynamics to investigate its properties and behavior. We find that a Polytropic gas may exhibit the dark energy like behavior in the large volume and low temperature limits. It also may be used to simulate a fluid with zero pressure at the small volume and high temperature limits. Briefly, our study shows that this gas may be used to describe the universe expansion history from the matter dominated era to the current accelerating era. By applying some initial condition to the system, we can establish a relation between the Polytropic gas parameters and initial conditions. Relationships with related works has also been addressed.
Dark energy with polytropic equation of state
Utpal Mukhopadhyay; Saibal Ray
2005-10-19
Equation of state parameter plays a significant role for guessing the real nature of dark energy. In the present paper polytropic equation of state $p=\\omega\\rho^n$ is chosen for some of the kinematical $\\Lambda$-models viz., $\\Lambda \\sim (\\dot a/a)^2$, $\\Lambda \\sim \\ddot a/a$ and $\\Lambda \\sim \\rho$. Although in dust cases ($\\omega=0$) closed form solutions show no dependency on the polytropic index $n$, but in non-dust situations some new possibilities are opened up including phantom energy with supernegative ($\\omegastate parameter.
On the solution topologies of polytropic winds
NASA Technical Reports Server (NTRS)
Bailyn, C.; Rosner, R.; Tsinganos, K.
1985-01-01
Steady polytropic wind flows are studied by examining their solution topologies. The problem of whether the degeneracy of the continuous and standing shocked solutions in the isothermal case persist in the more general case of a polytropic expanding atmosphere is addressed. The effects of departures from spherical symmetry and nonthermal momentum addition are considered within the context of the new class of magnetospheric models proposed by Low and Tsinganos (1985). The flow near the boundary of a polar coronal hole is considered for the specific case of a magnetosphere in which this boundary asymptotically approaches the equator at large heliocentric distances.
Magnetic flux concentrations in a polytropic atmosphere
NASA Astrophysics Data System (ADS)
Losada, I. R.; Brandenburg, A.; Kleeorin, N.; Rogachevskii, I.
2014-04-01
Context. Strongly stratified hydromagnetic turbulence has recently been identified as a candidate for explaining the spontaneous formation of magnetic flux concentrations by the negative effective magnetic pressure instability (NEMPI). Much of this work has been done for isothermal layers, in which the density scale height is constant throughout. Aims: We now want to know whether earlier conclusions regarding the size of magnetic structures and their growth rates carry over to the case of polytropic layers, in which the scale height decreases sharply as one approaches the surface. Methods: To allow for a continuous transition from isothermal to polytropic layers, we employ a generalization of the exponential function known as the q-exponential. This implies that the top of the polytropic layer shifts with changing polytropic index such that the scale height is always the same at some reference height. We used both mean-field simulations (MFS) and direct numerical simulations (DNS) of forced stratified turbulence to determine the resulting flux concentrations in polytropic layers. Cases of both horizontal and vertical applied magnetic fields were considered. Results: Magnetic structures begin to form at a depth where the magnetic field strength is a small fraction of the local equipartition field strength with respect to the turbulent kinetic energy. Unlike the isothermal case where stronger fields can give rise to magnetic flux concentrations at larger depths, in the polytropic case the growth rate of NEMPI decreases for structures deeper down. Moreover, the structures that form higher up have a smaller horizontal scale of about four times their local depth. For vertical fields, magnetic structures of super-equipartition strengths are formed, because such fields survive downward advection that causes NEMPI with horizontal magnetic fields to reach premature nonlinear saturation by what is called the "potato-sack" effect. The horizontal cross-section of such structures found in DNS is approximately circular, which is reproduced with MFS of NEMPI using a vertical magnetic field. Conclusions: Results based on isothermal models can be applied locally to polytropic layers. For vertical fields, magnetic flux concentrations of super-equipartition strengths form, which supports suggestions that sunspot formation might be a shallow phenomenon.
Observing forbidden radiative decay of highly charged ions in a compact Penning trap
NASA Astrophysics Data System (ADS)
Brewer, Samuel M.; Guise, Nicholas D.; Tan, Joseph N.
2012-06-01
We report observations of radiative decay from metastable states of highly charged ions captured in a newly-developed compact Penning trap. Ions of interest are created in the NIST electron beam ion trap (EBIT), extracted in an ion beamline, and captured in a compact Penning trap built in a novel unitary architecture to facilitate collection of photons emitted by stored ions. As an example, Ar^13+ ions are captured in one of the two fine structure levels forming the lowest lying states, allowing us to monitor the fluorescence (blue light) of the spin-flipping (M1) decay to the ground state. We present recent results from the newly deployed ion capture apparatus and briefly discuss previous in-EBIT experiments as well as an earlier study involving ion capture in an electrostatic Kingdon ion trap. Our results illustrate the potential of unitary Penning traps for a variety of studies,ootnotetextJ. N. Tan, et. al., ``Unitary Penning Traps,'' at this meeting (poster). including experiments to produce hydrogenlike ions for spectroscopic tests of QED.ootnotetextN.D. Guise, et. al., ``Charge Exchange and spectroscopy with isolated highly charged ions,'' at this meeting.
Sharma, Surender Kumar; Shyam, Anurag
2015-02-01
High energy capacitor bank is used for primary electrical energy storage in pulsed power drivers. The capacitors used in these pulsed power drivers have low inductance, low internal resistance, and less dc life, so it has to be charged rapidly and immediately discharged into the load. A series resonant converter based 45 kV compact power supply is designed and developed for rapid charging of the capacitor bank with constant charging current up to 150 mA. It is short circuit proof, and zero current switching technique is used to commute the semiconductor switch. A high frequency resonant inverter switching at 10 kHz makes the overall size small and reduces the switching losses. The output current of the power supply is limited by constant on-time and variable frequency switching control technique. The power supply is tested by charging the 45 kV/1.67 ?F and 15 kV/356 ?F capacitor banks. It has charged the capacitor bank up to rated voltage with maximum charging current of 150 mA and the average charging rate of 3.4 kJ/s. The output current of the power supply is limited by reducing the switching frequency at 5 kHz, 3.3 kHz, and 1.7 kHz and tested with 45 kV/1.67 ?F capacitor bank. The protection circuit is included in the power supply for over current, under voltage, and over temperature. The design details and the experimental testing results of the power supply for resonant current, output current, and voltage traces of the power supply with capacitive, resistive, and short circuited load are presented and discussed. PMID:25725838
NASA Astrophysics Data System (ADS)
Sharma, Surender Kumar; Shyam, Anurag
2015-02-01
High energy capacitor bank is used for primary electrical energy storage in pulsed power drivers. The capacitors used in these pulsed power drivers have low inductance, low internal resistance, and less dc life, so it has to be charged rapidly and immediately discharged into the load. A series resonant converter based 45 kV compact power supply is designed and developed for rapid charging of the capacitor bank with constant charging current up to 150 mA. It is short circuit proof, and zero current switching technique is used to commute the semiconductor switch. A high frequency resonant inverter switching at 10 kHz makes the overall size small and reduces the switching losses. The output current of the power supply is limited by constant on-time and variable frequency switching control technique. The power supply is tested by charging the 45 kV/1.67 ?F and 15 kV/356 ?F capacitor banks. It has charged the capacitor bank up to rated voltage with maximum charging current of 150 mA and the average charging rate of 3.4 kJ/s. The output current of the power supply is limited by reducing the switching frequency at 5 kHz, 3.3 kHz, and 1.7 kHz and tested with 45 kV/1.67 ?F capacitor bank. The protection circuit is included in the power supply for over current, under voltage, and over temperature. The design details and the experimental testing results of the power supply for resonant current, output current, and voltage traces of the power supply with capacitive, resistive, and short circuited load are presented and discussed.
Gravity modes in rapidly rotating polytropic stars
Ballot, J; Reese, D R; Rieutord, M
2009-01-01
Using the Two-dimensional Oscillation Program (TOP), we have explored the effects of rapid rotation on gravity modes in polytropic stars. Coriolis force, centrifugal distortion as well as compressible effects have been taken into account. Thanks to our complete calculation, we have first studied the validity domain of perturbative methods and started to explore properties of these modes. We focus on l=1 in this analysis.
Polytropic dark haloes of elliptical galaxies
NASA Astrophysics Data System (ADS)
Saxton, Curtis J.; Ferreras, Ignacio
2010-06-01
The kinematics of stars and planetary nebulae in early-type galaxies provide vital clues to the enigmatic physics of their dark matter haloes. We fit published data for 14 such galaxies using a spherical, self-gravitating model with two components: (i) a Sérsic stellar profile fixed according to photometric parameters, and (ii) a polytropic dark matter halo that conforms consistently to the shared gravitational potential. The polytropic equation of state can describe extended theories of dark matter involving self-interaction, non-extensive thermostatistics or boson condensation (in a classical limit). In such models, the flat-cored mass profiles widely observed in disc galaxies are due to innate dark physics, regardless of any baryonic agitation. One of the natural parameters of this scenario is the number of effective thermal degrees of freedom of dark matter (Fd) which is proportional to the dark heat capacity. By default, we assume a cosmic ratio of baryonic and dark mass. Non-Sérsic kinematic ideosyncrasies and possible non-sphericity thwart fitting in some cases. In all 14 galaxies, the fit with a polytropic dark halo improves or at least gives similar fits to the velocity dispersion profile, compared to a stars-only model. The good halo fits usually prefer Fd values from six to eight. This range complements the recently inferred limit of 7 < Fd < 10, derived from constraints on galaxy cluster core radii and black hole masses. However, a degeneracy remains: radial orbital anisotropy or a depleted dark mass fraction could shift our models' preference towards lower Fd; whereas a loss of baryons would favour higher Fd.
Warm-polytropic inflationary universe model
M. R. Setare; M. J. S. Houndjo; V. Kamali
2013-07-02
In the present paper we study warm inflationary universe models in the context of a polytropic gas. We derive the characteristics of this model in slow-roll approximation and develop our model in two cases, 1- For a constant dissipative parameter $\\Gamma$. 2- $\\Gamma$ as a function of scalar field $\\phi$. In these cases we will obtain exact solution for the scalar field and Hubble parameter. We will also obtain explicit expressions for the tensor-scalar ratio $R$, scalar spectrum index $n_s$ and its running $\\alpha_s$, in slow-roll approximation.
Charged Particle Dynamics in the Field of a Slowly Rotating Compact Star
Babur M. Mirza
2004-09-07
We study the dynamics of a charged particle in the field of a slowly rotating compact star in the gravitoelectromagnetic approximation to the geodesic equation . The star is assumed to be surrounded by an ideal, highly conducting plasma (taken as a magnetohydrodynamic fluid) with a stationary, axially symmetric electromagnetic field. The general relativistic Maxwell equations are solved to obtain the effects of the background spacetime on the electromagnetic field in the linearized Kerr spacetime. The equations of motion are then set up and solved numerically to incorporate the gravitational as well as the electromagnetic effects. The analysis shows that in the slow rotation approximation the frame dragging effects on the electromagnetic field are absent. However the particle is directly effected by the rotating gravitational source such that close to the star the gravitational and electromagnetic field produce contrary effects on the particle's trajectory.
Polytropes: Implications for Molecular Clouds and Dark Matter
Christopher F. McKee
2000-08-02
Polytropic models are reasonably successful in acounting for the observed features of molecular clouds. Multi-pressure polytropes include the various pressure components that are important in molecular clouds, whereas composite polytropes provide a representation for the core halo structure. Small, very dense (n~10^{11} cm^{-3}) molecular clouds have been proposed as models for both dark matter and for extreme scattering events. Insofar as the equation of state in these clouds can be represented by a single polytropic relation (pressure varies as a power of the density), such models conflict with observation. It is possible to contrive composite polytropes that do not conflict with observation, but whether the thermal properties of the clouds are consistent with such structure remains to be determined.
Plasser, Felix; Thomitzni, Benjamin; Bäppler, Stefanie A; Wenzel, Jan; Rehn, Dirk R; Wormit, Michael; Dreuw, Andreas
2015-08-01
We report the development of a set of excited-state analysis tools that are based on the construction of an effective exciton wavefunction and its statistical analysis in terms of spatial multipole moments. This construction does not only enable the quantification of the spatial location and compactness of the individual hole and electron densities but also correlation phenomena can be analyzed, which makes this procedure particularly useful when excitonic or charge-resonance effects are of interest. The methods are first applied to bianthryl with a focus on elucidating charge-resonance interactions. It is shown how these derive from anticorrelations between the electron and hole quasiparticles, and it is discussed how the resulting variations in state characters affect the excited-state absorption spectrum. As a second example, cytosine is chosen. It is illustrated how the various descriptors vary for valence, Rydberg, and core-excited states, and the possibility of using this information for an automatic characterization of state characters is discussed. © 2015 Wiley Periodicals, Inc. PMID:26119286
José P. S. Lemos; Francisco J. Lopes; Gonçalo Quinta; Vilson T. Zanchin
2015-01-09
One of the stiffest equations of state for matter in a compact star is constant energy density and this generates the interior Schwarzschild radius to mass relation and the Misner maximum mass for relativistic compact stars. If dark matter populates the interior of stars, and this matter is supersymmetric or of some other type, some of it possessing a tiny electric charge, there is the possibility that highly compact stars can trap a small but non-negligible electric charge. In this case the radius to mass relation for such compact stars should get modifications. We use an analytical scheme to investigate the limiting radius to mass relation and the maximum mass of relativistic stars made of an incompressible fluid with a small electric charge. The investigation is carried out by using the hydrostatic equilibrium equation, i.e., the Tolman-Oppenheimer-Volkoff (TOV) equation, together with the other equations of structure, with the further hypothesis that the charge distribution is proportional to the energy density. The approach relies on Volkoff and Misner's method to solve the TOV equation. For zero charge one gets the interior Schwarzschild limit, and supposing incompressible boson or fermion matter with constituents with masses of the order of the neutron mass one gets that the maximum mass is the Misner mass. For a small electric charge, our analytical approximating scheme valid in first order in the star's electric charge, shows that the maximum mass increases relatively to the uncharged case, whereas the minimum possible radius decreases, an expected effect since the new field is repulsive aiding the pressure to sustain the star against gravitational collapse.
A variable polytrope index applied to planet and material models
NASA Astrophysics Data System (ADS)
Weppner, S. P.; McKelvey, J. P.; Thielen, K. D.; Zielinski, A. K.
2015-09-01
We introduce a new approach to a century-old assumption which enhances not only planetary interior calculations but also high-pressure material physics. We show that the polytropic index is the derivative of the bulk modulus with respect to pressure. We then augment the traditional polytrope theory by including a variable polytrope index within the confines of the Lane-Emden differential equation. To investigate the possibilities of this method, we create a high-quality universal equation of state, transforming the traditional polytrope method to a tool with the potential for excellent predictive power. The theoretical foundation of our equation of state is the same elastic observable which we found equivalent to the polytrope index, the derivative of the bulk modulus with respect to pressure. We calculate the density-pressure of six common materials up to 1018 Pa, mass-radius relationships for the same materials, and produce plausible density-radius models for the rocky planets of our Solar system. We argue that the bulk modulus and its derivatives have been underutilized in previous planet formation methods. We constrain the material surface observables for the inner core, outer core, and mantle of planet Earth in a systematic way including pressure, bulk modulus, and the polytrope index in the analysis. We believe that this variable polytrope method has the necessary apparatus to be extended further to gas giants and stars. As supplemental material we provide computer code to calculate multi-layered planets.
Holographic polytropic $f(T)$-gravity models
Chattopadhyay, Surajit; Rani, Shamaila
2015-01-01
The present paper reports a study on the cosmological consequences arising from reconstructing $f(T)$ gravity through new holographic-polytropic dark energy. We assume two approaches, namely a particular form of Hubble parameter $H$ and a solution for $f(T)$. We obtain the deceleration parameter, effective equation of state as well as torsion equation of state parameters from total density and pressure in both cases. It is interesting to mention here that the deceleration and torsion equation of state represent transition from deceleration to acceleration phase. We study the statefinder parameters under both approaches which result that statefinder trajectories are found to attain $\\Lambda$CDM point. The comparison with observational data represents consistent results. Also, we discuss the stability of reconstructed models through squared speed of sound which represents stability in late times.
On spherically-symmetric accretion by a collisionless polytrope
B. M. Lewis
2001-04-02
An isolated, spherically-symmetric, self-gravitating, collisionless system is always a polytrope when it reaches equilibrium (Nakamura 2000). This strongly suggests as a corollary, however, that the same polytrope dominates its precursor states, since the dynamical equations for its constituents can be time-reversed. Moreover this assumption, which precludes a polytrope from ever accreting 100% of the mass from an infalling shell, as a subsequent state will eventually be a polytrope, is confirmed now by our finding that a collisionless polytrope cannot accrete 100% of an infalling shell while simultaneously guaranteeing that the entropy of the Universe as a whole increases. These strictures are only evaded by the shedding of some mass. A polytrope must lose mass to gain mass. We deduce from the time-reversible property of a collisionless polytrope that the scalar sum, P, over constituent momenta in its rest frame is an independent state variable that is conserved with respect to its surface radius through interactions between a polytrope and an infalling shell. This new constraint, together with conservation of energy, enables us (i) to show that an isolated polytrope is indeed stable against spherically-symmetric mass-loss, which is the essential content of our initial assumption; (ii) to calculate both the velocity and the fraction of infall-mass returned to infinity, provided the "accretion law" between the change in mass and surface radius is specified. Numerical results confirm a frequent empirical finding (Livio 2000) that the velocity of a mass outflow is of the same order of magnitude as the escape velocity from the system.
Compact formulae, dynamics and radiation of charged particles under synchro-curvature losses
NASA Astrophysics Data System (ADS)
Viganò, Daniele; Torres, Diego F.; Hirotani, Kouichi; Pessah, Martín E.
2015-02-01
We consider the fundamental problem of charged particles moving along and around a curved magnetic field line, revising the synchro-curvature radiation formulae introduced by Cheng & Zhang. We provide more compact expressions to evaluate the spectrum emitted by a single particle, identifying the key parameter that controls the transition between the curvature-dominated and the synchrotron-dominated regime. This parameter depends on the local radius of curvature of the magnetic field line, the gyration radius, and the pitch angle. We numerically solve the equations of motion for the emitting particle by considering self-consistently the radiative losses, and provide the radiated spectrum produced by a particle when an electric acceleration is balanced by its radiative losses, as it is assumed to happen in the outer gaps of pulsar's magnetospheres. We compute the average spectrum radiated throughout the particle trajectory finding that the slope of the spectrum before the peak depends on the location and size of the emission region. We show how this effect could then lead to a variety of synchro-curvature spectra. Our results reinforce the idea that the purely synchrotron or curvature losses are, in general, inadequate to describe the radiative reaction on the particle motion, and the spectrum of emitted photons. Finally, we discuss the applicability of these calculations to different astrophysical scenarios.
Interacting polytropic gas model of phantom dark energy in non-flat universe
K. Karami; S. Ghaffari; J. Fehri
2009-11-25
By introducing the polytropic gas model of interacting dark energy, we obtain the equation of state for the polytropic gas energy density in a non-flat universe. We show that for even polytropic index by choosing $K>Ba^{\\frac{3}{n}}$, one can obtain $\\omega^{\\rm eff}_{\\Lambda}universe dominated by phantom dark energy.
Largetime behavior of solutions to the equations of a onedimensional viscous polytropic ideal gas in
LargeÂtime behavior of solutions to the equations of a oneÂdimensional viscous polytropic ideal gas and initial boundary value problems for a oneÂ dimensional viscous polytropic ideal gas in unbounded domains to the equations of motion of a oneÂdimensional viscous polytropic ideal gas in unbounded domains. The motion
Symmetry Reduction of Lane-Emden Equation for Polytropes
Babur M. Mirza
2008-07-03
We describe an ansatz for symmetry reduction of the Lane-Emden equation for an arbitrary polytropic index n, admitting only one symmetry generator. For the reduced first order differential equation it is found that standard reduction procedure do not admit any non-trivial Lie point symmetry. However some special solutions for the differential equation are obtained.
Scalar field cosmology with polytropic and causal viscous fluids
NASA Astrophysics Data System (ADS)
Singha, Anup Kumar; Debnath, Ujjal
2008-04-01
In this paper, we have considered a model for FRW space-time in the presence of coupled scalar field ? and potential V( ?) with causal viscous fluid and polytropic fluid. We have shown that irrespective of fluid the causality theory provides late time acceleration of the universe. In all cases, the potential always decreases due to evolution of the universe.
The structure of normal shock waves in polytropic gases
Omar Badr
1984-01-01
The formation and structure of normal shock waves in compressible, polytropic gases is investigated using the continuum gas dynamical equations. A phenomenological model for temperature-dependent viscosity and thermal conductivity is preassumed. The fundamental resulting nonlinear differential equation is solved exactly, and the complete structure of the shock wave is determined. It is found that the flow quantities and characteristics depend
Warm-Polytropic Cosmology with and Without Bulk Viscosity
NASA Astrophysics Data System (ADS)
Saadat, Hassan
2014-12-01
In this paper we consider warm-polytropic cosmology including bulk viscosity and study cosmological parameters. We can obtain effect of viscosity on the important cosmological parameters such as Hubble expansion, deceleration and scale factor parameters. We compare our results with observational data and fix our solution. We find that the bulk viscosity increases both energy density and Hubble expansion parameter.
Supersymmetric formulation of polytropic gas dynamics and its invariant solutions
Grundland, A. M.; Hariton, A. J.
2011-04-15
In this paper, a supersymmetric extension of the polytropic gas dynamics equations is constructed through the use of a superspace involving two independent fermionic variables and two bosonic superfields. A superalgebra of symmetries of the proposed extended model is determined and a systematic classification of the one-dimensional subalgebras of this superalgebra is performed. Through the use of the symmetry reduction method, a number of invariant solutions of the supersymmetric polytropic gas dynamics equations are found. Several types of solutions are obtained including algebraic-type solutions and propagation waves (simple and double waves). Many of the obtained solutions involve arbitrary functions of one or two bosonic or fermionic variables. In the case where the arbitrary functions involve only the independent fermionic variables, the solutions are expressed in terms of Taylor expansions.
NASA Astrophysics Data System (ADS)
Liu, Feilong; Zhang, Jian; He, Frank; Liu, Feng; Zhang, Lining; Chan, Mansun
2009-01-01
This paper presents a charge-based compact model for predicting the current-voltage and capacitance-voltage characteristics of heavily doped long-channel cylindrical surrounding-gate (SRG) MOSFETs. Starting from Poisson's equation with fixed charge and inversion charge terms, a closed-form equation of inversion charge is obtained with the full-depletion approximation. Substituting this inversion charge expression into Pao-Sah's dual integral, a drain current expression with concise form is derived. Based on the Ward-Dutton linear-charge-partition method and the current continuity principle, all trans-capacitances are obtained analytically. The developed model is valid in all operation regions from the sub-threshold to strong inversion and from the linear to the saturation region without any smooth function. The model predictions have been extensively compared with 3D numerical simulations and a good agreement is observed in most of the operation regions with a wide range of geometrical parameters.
Is scalar-tensor gravity consistent with polytropic stellar models?
NASA Astrophysics Data System (ADS)
Henttunen, K.; Vilja, I.
2015-05-01
We study the scalar field potential V(phi) in the scalar-tensor gravity with self-consistent polytropic stellar configurations. Without choosing a particular potential, we numerically derive the potential inside various stellar objects. We restrict the potential to conform to general relativity or to f(R) gravity inside and require the solution to arrive at SdS vacuum at the surface. The studied objects are required to obtain observationally valid masses and radii corresponding to solar type stars, white dwarfs and neutron stars. We find that the resulting scalar-tensor potential V(phi) for the numerically derived polytrope that conforms to general relativity, in each object class, is highly dependent on the matter configuration as well as on the vacuum requirement at the boundary. As a result, every stellar configuration arrives at a potential V(phi) that is not consistent with the other stellar class potentials. Therefore, a general potential that conforms to all these polytropic stellar classes could not be found.
Sinuous oscillations and steady warps of polytropic disks
Balmforth, N.J.; Spiegel, E.A.
1995-05-01
In an asymptotic development of the equations governing the equilibria and linear stability of rapidly rotating polytropes we employed the slender aspect of these objects to reduce the three-dimensional partial differential equations to a somewhat simpler, ordinary integro-differential form. The earlier calculations dealt with isolated objects that were in centrifugal balance, that is the centrifugal acceleration of the configuration was balanced largely by self gravity with small contributions from the pressure gradient. Another interesting situation is that in which the polytrope rotates subject to externally imposed gravitational fields. In astrophysics, this is common in the theory of galactic dynamics because disks are unlikely to be isolated objects. The dark halos associated with disks also provide one possible explanation of the apparent warping of many galaxies. If the axis of the highly flattened disk is not aligned with that of the much less flattened halo, then the resultant torque of the halo gravity on the disk might provide a nonaxisymmetric distortion or disk warp. Motivated by these possibilities we shall here build models of polytropic disks of small but finite thickness which are subjected to prescribed, external gravitational fields. First we estimate how a symmetrical potential distorts the structure of the disk, then we examine its sinuous oscillations to confirm that they freely decay, hence suggesting that a warp must be externally forced. Finally, we consider steady warps of the disk plane when the axis of the disk does not coincide with that of the halo.
Neutron sources for BNCT using low-power research reactors or compact charged particle accelerators
NASA Astrophysics Data System (ADS)
Harker, Yale D.; Nigg, David W.; Mitchell, Hannah E.; Wheeler, Floyd J.; Jones, James L.
1997-02-01
Since 1986, the Idaho National Engineering Laboratory (INEL) has been involved in the development of epithermal neutron sources for BNCT. The INEL effort was instrumental in the implementation of an epithermal neutron beam at the Brookhaven Medical Research Reactor at Brookhaven National Laboratory. Recently, the INEL's effort has been directed toward developing advanced filter designs for use with low- power research reactors such as the 250W and 1MW class TRIGA reactors which are located at various sites and universities throughout the world. This work has focused on utilizing advanced filter materials that more effectively reduce fast neutron contamination in the epithermal neutron beam and at the same time optimize neutron economy. The INEL has also been involved in developing two concepts of producing neutron sources for BNCT using charged particle accelerators. The first concept involves the use of an electron accelerator/photoneutron source. The second concept involves the use of a charged particle beam in which the particle energy is just above the threshold energy of the reaction. This paper will review the progress made by INEL in modifying the WSU TRIGA reactor and conceptual development of an electron accelerator based photoneutron source for BNCT. The near threshold particle accelerator development will be discussed in a separate paper.
Near-polytropic stellar simulations with a radiative surface
NASA Astrophysics Data System (ADS)
Barekat, A.; Brandenburg, A.
2014-11-01
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
Caloric curves fitted by polytropic distributions in the HMF model
NASA Astrophysics Data System (ADS)
Campa, Alessandro; Chavanis, Pierre-Henri
2013-04-01
We perform direct numerical simulations of the Hamiltonian mean field (HMF) model starting from non-magnetized initial conditions with a velocity distribution that is (i) Gaussian; (ii) semi-elliptical, and (iii) waterbag. Below a critical energy E c , depending on the initial condition, this distribution is Vlasov dynamically unstable. The system undergoes a process of violent relaxation and quickly reaches a quasi-stationary state (QSS). We find that the distribution function of this QSS can be conveniently fitted by a polytrope with index (i) n = 2; (ii) n = 1; and (iii) n = 1/2. Using the values of these indices, we are able to determine the physical caloric curve T kin ( E) and explain the negative kinetic specific heat region C kin = dE/ d T kin < 0 observed in the numerical simulations. At low energies, we find that the system has a "core-halo" structure. The core corresponds to the pure polytrope discussed above but it is now surrounded by a halo of particles. In case (iii), we recover the "uniform" core-halo structure previously found by Pakter and Levin [Phys. Rev. Lett. 106, 200603 (2011)]. We also consider unsteady initial conditions with magnetization M 0 = 1 and isotropic waterbag velocity distribution and report the complex dynamics of the system creating phase space holes and dense filaments. We show that the kinetic caloric curve is approximately constant, corresponding to a polytrope with index n 0 ? 3.56 (we also mention the presence of an unexpected hump). Finally, we consider the collisional evolution of an initially Vlasov stable distribution, and show that the time-evolving distribution function f( ?,v,t) can be fitted by a sequence of polytropic distributions with a time-dependent index n( t) both in the non-magnetized and magnetized regimes. These numerical results show that polytropic distributions (also called Tsallis distributions) provide in many cases a good fit of the QSSs. They may even be the rule rather than the exception. However, in order to moderate our message, we also report a case where the Lynden-Bell theory (which assumes ergodicity or efficient mixing) provides an excellent prediction of an inhomogeneous QSS. We therefore conclude that both Lynden-Bell and Tsallis distributions may be useful to describe QSSs depending on the efficiency of mixing.
Polytropic dark matter flows illuminate dark energy and accelerated expansion
NASA Astrophysics Data System (ADS)
Kleidis, K.; Spyrou, N. K.
2015-04-01
Currently, a large amount of data implies that the matter constituents of the cosmological dark sector might be collisional. An attractive feature of such a possibility is that, it can reconcile dark matter (DM) and dark energy (DE) in terms of a single component, accommodated in the context of a polytropic-DM fluid. In fact, polytropic processes in a DM fluid have been most successfully used in modeling dark galactic haloes, thus significantly improving the velocity dispersion profiles of galaxies. Motivated by such results, we explore the time evolution and the dynamical characteristics of a spatially-flat cosmological model, in which, in principle, there is no DE at all. Instead, in this model, the DM itself possesses some sort of fluidlike properties, i.e., the fundamental units of the Universe matter-energy content are the volume elements of a DM fluid, performing polytropic flows. In this case, together with all the other physical characteristics, we also take the energy of this fluid's internal motions into account as a source of the universal gravitational field. This form of energy can compensate for the extra energy, needed to compromise spatial flatness, namely, to justify that, today, the total energy density parameter is exactly unity. The polytropic cosmological model, depends on only one free parameter, the corresponding (polytropic) exponent, ?. We find this model particularly interesting, because for ? ? 0.541, without the need for either any exotic DE or the cosmological constant, the conventional pressure becomes negative enough so that the Universe accelerates its expansion at cosmological redshifts below a transition value. In fact, several physical reasons, e.g., the cosmological requirement for cold DM (CDM) and a positive velocity-of-sound square, impose further constraints on the value of ?, which is eventually settled down to the range -0.089 < ? ? 0. This cosmological model does not suffer either from the age problem or from the coincidence problem. At the same time, this model reproduces to high accuracy the distance measurements performed with the aid of the supernovae (SNe) Type Ia standard candles, and most naturally interprets, not only when, but also why the Universe transits from deceleration to acceleration, thus arising as a mighty contestant for a DE model.
Analytical representations for simple and composite polytropes and their moments of inertia
NASA Astrophysics Data System (ADS)
Criss, Robert E.; Hofmeister, Anne M.
2015-04-01
Polytropes are widely applied in astrophysics. To facilitate their use, we derive analytical formulae for the moment of inertia as a function of polytropic index. We also provide 1- and 3-parameter equations that replicate the density variations in polytropic bodies to varying degrees of accuracy, determined by numerical calculations and analytical results for polytropic indices between 0 and 5. As an example, we construct a composite polytrope, suitable for gas giants, exoplanets, or tiny sub-solar dwarfs, wherein an inner sphere is modeled by constant density, which represents the density jump associated with production of a relatively incompressible solid, and an outer envelope is modeled as having a polytropic index near 2.5, which corresponds to a diatomic gas. Envelope sizes are constrained by the moment of inertia.
The Polytropic Equation of State of Interstellar Gas Clouds
Marco Spaans; Joseph Silk
2000-02-25
Models are presented for the polytropic equation of state of self-gravitating, quiescent interstellar gas clouds. A detailed analysis, including chemistry, thermal balance, and radiative transfer, is performed for the physical state of the gas as a function of density, metallicity, velocity field, and background radiation field. It is found that the stiffness of the equation of state strongly depends on all these physical parameters, and the adiabatic index varies between 0.2-1.4. The implications for star formation, in particular at high redshift and in starburst galaxies, and the initial stellar mass function are discussed.
Polytropic index of central plasma sheet ions based on MHD Bernoulli integral
NASA Astrophysics Data System (ADS)
Pang, Xuexia; Cao, Jinbin; Liu, Wenlong; Ma, Yuduan; Lu, Haoyu; Yang, Junying; Li, Liuyuan; Liu, Xu; Wang, Jing; Wang, Tieyan; Yu, Jiang
2015-06-01
This paper uses the data of Cluster from 2001 to 2009 to study the polytropic processes of central plasma sheet (CPS) ions. We first adopt the approach of MHD Bernoulli integral (MBI) to identify homogeneous streamflow tubes (quasi-invariant MBI regions) and then calculate the polytropic index of ions for those streamflow tubes whose outward electromagnetic energy ratios ? < 0.05. The central plasma sheet is actually a complicated system, which comprises many streamflow tubes with different polytropic relations and the transition layers in between. The polytropic indexes of the CPS ions range from 0.1 to 1.8 and have a quasi-Gaussian distribution. The median polytropic index is 0.93 for AE < 200 nT and 0.91 for AE ? 200 nT. Thus, there is no obvious difference between the polytropic indexes of the quiet time and the substorm time CPS ions, which suggests that the thinning and thickening processes of plasma sheet during substorm times do not change obviously the polytropic relation of the CPS ions. The statistical analysis using different ? (? < 0.05, 0.025, and 0.01) shows that the outward emission of electromagnetic energy is an effective cooling mechanism and can make the polytropic index to decrease and shift toward isobaric. It is inferred that the CPS ions as a whole much likely behave in a way between isobaric and isothermal.
NASA Astrophysics Data System (ADS)
Bornschein, Russell E.; Niu, Shuai; Eschweiler, Joseph; Ruotolo, Brandon T.
2015-09-01
Protocols that aim to construct complete models of multiprotein complexes based on ion mobility and mass spectrometry data are becoming an important element of integrative structural biology efforts. However, the usefulness of such data is predicated, in part, on an ability to measure individual subunits removed from the complex while maintaining a compact/folded state. Gas-phase dissociation of intact complexes using collision induced dissociation is a potentially promising pathway for acquiring such protein monomer size information, but most product ions produced are possessed of high charge states and elongated/string-like conformations that are not useful in protein complex modeling. It has previously been demonstrated that the collision induced dissociation of charge-reduced protein complexes can produce compact subunit product ions; however, their formation mechanism is not well understood. Here, we present new experimental evidence for the avidin (64 kDa) and aldolase (157 kDa) tetramers that demonstrates significant complex remodeling during the dissociation of charge-reduced assemblies. Detailed analysis and modeling indicates that highly compact intermediates are accessed during the dissociation process by both complexes. Here, we present putative pathways that describe the formation of such ions, as well as discuss the broader significance of such data for structural biology applications moving forward.
Coalescing neutron stars - gravitational waves from polytropic models.
NASA Astrophysics Data System (ADS)
Ruffert, M.; Rampp, M.; Janka, H.-T.
1997-05-01
The dynamics, time evolution of the mass distribution, and gravitational wave signature of coalescing neutron stars described by polytropes are compared with three simulations published previously: (a) "Run 2" of Zhuge et al. (1994PhRvD..50.6247Z), (b) "Model III" of Shibata et al. (1992, Prog, Theor. Phys. 88, 1079), and (c) "Model A64" of Ruffert et al. (1996A&A...311..532R). We aim at studying the differences due to the use of different numerical methods, different implementations of the gravitational wave backreaction, and different equations of state. We integrate the three-dimensional Newtonian equations of hydrodynamics by the Riemann-solver based "Piecewise Parabolic Method" on an equidistant Cartesian grid. Comparison (a) confronts the results of our grid-based PPM scheme with those from an SPH code. We find that due to the lower numerical viscosity of the PPM code, the post-merging oscillations and pulsations can be followed for a longer time and lead to larger secondary and tertiary maxima of the gravitational wave luminosity and to a stronger peak of the gravitational wave spectrum at a frequency of about f=~1.8KHz when compared to the results of Zhuge et al. (1994PhRvD..50.6247Z). In case (b) two grid based codes with the same backreaction formalism but differing hydrodynamic integrators and slightly different initial conditions are compared. Instead of rotationally deformed initial neutron stars we use spherically shaped stars. Satisfactory agreement of the amplitude of the gravitational wave luminosity is established, although due to the different initial conditions a small time delay develops in the onset of the dynamical instability setting in when the two stars come very close. In (c) we find that using a polytropic equation of state instead of the high-density equation of state of Lattimer & Swesty (1991, Nucl. Phys. A535, 331) employed by Ruffert et al. (1996A&A...311..532R) does not change the overall dynamical evolution of the merger and yields agreement of the gravitational wave signature to within 20% accuracy. Whereas the polytropic law describes the dynamical behaviour of the bulk of the matter at and above nuclear density sufficiently well, we, however, find clear differences of the structure and evolution of the outer layers of the neutron stars where the stiffness of the equation of state is largely overestimated. This has important implications for questions like mass loss and disk formation during the merging of binary neutron stars.
The thickness of the magnetosheath - Constraints on the polytropic index
NASA Astrophysics Data System (ADS)
Farris, M. H.; Petrinec, S. M.; Russell, C. T.
1991-10-01
The average positions and shapes of the bow shock and the magnetosphere were determined, using the results of a statistical analysis of 351 independent bow shock crossings and 233 independent magnetopause crossings by the ISEE-1 spacecraft in the years 1977-1980. Ellipsoidal models of the respective boundaries were obtained. The standoff distances for the bow shock and the magnetopause were found to be 13.7 +/-0.2 R(E) and 10.3 +/-0.3 R(E), respectively; with these values and the average upstream magnetosonic Mach number for this time period, the polytropic index gamma was calculated using the empirical relation of Spreiter et al. (1966).
Polytropic equilibrium and normal modes in cold atomic traps
NASA Astrophysics Data System (ADS)
Terças, H.; Mendonça, J. T.
2013-08-01
The compressibility limit of a cold gas confined in a magneto-optical trap due to multiple scattering of light is a long-standing problem. This scattering mechanism induces long-range interactions in the system, which are responsible for the occurrence of plasma-like phenomena. In the present paper, we investigate the importance of the long-range character of the mediated atom-atom interaction in the equilibrium and dynamical features of a magneto-optical trap. Making use of a hydrodynamical formulation, we derive a generalized Lane-Emden equation modeling the polytropic equilibrium of a magneto-optical trap, allowing us to describe the crossover between the two limiting cases: temperature-dominated and multiple-scattering-dominated traps. The normal collective modes of the system are also computed.
Shear instabilities in a fully compressible polytropic atmosphere
NASA Astrophysics Data System (ADS)
Witzke, V.; Silvers, L. J.; Favier, B.
2015-05-01
Shear flows have a significant impact on the dynamics in an assortment of different astrophysical objects, including accretion discs and stellar interiors. Investigating shear flow instabilities in a polytropic atmosphere provides a fundamental understanding of the motion in stellar interiors where turbulent motions, mixing processes, and magnetic field generation take place. Here, a linear stability analysis for a fully compressible fluid in a two-dimensional Cartesian geometry is carried out. Our study focuses on determining the critical Richardson number for different Mach numbers and the destabilising effects of high thermal diffusion. We find that there is a deviation in the predicted stability threshold for moderate Mach number flows, along with a significant effect on the growth rate of the linear instability for small Péclet numbers. We show that in addition to a Kelvin-Helmholtz instability, a Holmboe instability can appear, and we discuss the implication of this in stellar interiors.
Coalescing neutron stars -- gravitational waves from polytropic models
M. Ruffert; M. Rampp; H. -Th. Janka
1996-11-07
The dynamics, time evolution of the mass distribution, and gravitational wave signature of coalescing neutron stars described by polytropes are compared with three simulations published previously: (a) ``Run 2'' of Zhuge et al. (1994), (b) ``Model III'' of Shibata et al. (1992), and (c) ``Model A64'' of Ruffert et al. (1996). We aim at studying the differences due to the use of different numerical methods, different implementations of the gravitational wave backreaction, and different equations of state. Comparison (a) confronts the results of our grid-based PPM scheme with those from an SPH code. We found that due to the lower numerical viscosity of the PPM code, the post-merging oscillations and pulsations could be followed for a longer time and lead to larger secondary and tertiary maxima of the gravitational wave luminosity. In case (b) two grid based codes with the same backreaction formalism but differing hydrodynamic integrators and different numerical resolution are compared. Satisfactory agreement of the amplitude of the gravitational wave luminosity is established, although due to the different initial conditions a small time delay develops in the onset of the dynamical instability. In (c) we find that using a polytropic equation of state instead of the high-density equation of state of Lattimer & Swesty (1991) does not change the overall dynamical evolution of the merger and yields agreement of the gravitational wave signature to within 20% accuracy. However, differences of the structure and evolution of the outer layers of the neutron stars are present, which has important implications for questions like mass loss and disk formation during the merging of binary neutron stars.
NASA Astrophysics Data System (ADS)
Bendib, T.; Djeffal, F.; Arar, D.
2013-04-01
The analytical modeling of nanoscale devices is an important area of computer-aided design for fast and accurate nanoelectronic design and optimization. In the present paper, a new approach for modeling semiconductor devices, nanoscale double gate DG MOSFETs, by use of the gradual channel approximation (GC) approach and genetic algorithm optimization technique (GA) is presented. The proposed approach combines the universal optimization and fitting capability of GA and the cost-effective optimization concept of quantum correction, to achieve reliable, accurate and simple compact models for nanoelectronic circuit simulations. Our compact models give good predictions of the quantum capacitance, threshold voltage shift, quantum inversion charge density and drain current. These models have been verified with 2D self-consistent results from numerical calculations of the coupled Poisson-Schrödinger equations. The developed models can also be incorporated into nanoelectronic circuit simulators to study the nanoscale CMOS-based devices without impact on the computational time and data storage.
NASA Technical Reports Server (NTRS)
Lai, Dong; Rasio, Frederic A.; Shapiro, Stuart L.
1993-01-01
The results of Chandrasekhar (1969) are generalized to polytropes, using a formalism based on ellipsoidal energy variational principle to construct approximate stellar equilibrium solutions and study their stability. After reviewing the energy variational method and describing the approach, several equivalent stability conditions are established and secular vs. dynamical instabilities are discussed. Then, the equilibrium structure equations are derived for isolated, rotating polytropes, and axisymmetric configurations (compressible Maclaurin spheroids) are considered. Particular attention is given to triaxial configurations, either in a state of uniform rotation (generalizing the classical Jacobi ellipsoids) or with internal fluid motions of uniform vorticity (the compressible analogues of Riemann-S ellipsoids) and to the stability of these single star configurations. The compressible generalizations of the Roche and Roche-Riemann problems for a polytrope in orbit about a point-mass companion are solved, and the generalized Darwin problem for two identical polytropes in a binary is considered.
NASA Astrophysics Data System (ADS)
Farrell, Christopher Patrick
Proton-proton collisions at the Large Hadron Collider at sqrt(s) = 7 and 8 TeV are studied using the Compact Muon Solenoid (CMS) detector. The measurement and improvements to the arrival time of particles to the muon system of CMS are detailed. The timing is used to associate the particle with the correct proton-proton crossing and to classify the particle. Additionally, four analyses are presented that use timing and ionization energy loss to search for the production of long-lived charged particles predicted in many theories of new physics. The searches are sensitive to a variety of signatures, including the possibility that the particles will only be detectable during part of their passage through the CMS detector. Limits are placed on the production of long-lived gluinos, stops, staus, and multiply-charged particles. The limits are the most stringent in the world to date.
Furman, M.A.
2007-05-29
By combining the method of images with calculus of complex variables, we provide a simple expression for the electric field of a two-dimensional (2D) static elliptical charge distribution inside a perfectly conducting cylinder. The charge distribution need not be concentric with the cylinder.
NASA Astrophysics Data System (ADS)
Dai, Qiu-Sheng; Zhao, Cui-Lan; Zhang, Hua-Lin; Qi, Yu-Jin
2010-08-01
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.
The Polytropic Equation of State of Primordial Gas Clouds
Marco Spaans; Joseph Silk
2005-03-05
The polytropic equation of state (EOS) of primordial gas clouds with modest enrichment is computed, motivated by the recent observations of very Fe-deficient stars, [Fe/H]~10^{-3.5}-10^{-5}, such as HE 0107-5240 and CS 29498-043. These stars are overabundant, relative to Fe, in C and O. We assume that the observed abundances of species like C, O, Si and Fe are representative of the gas from which the currently observed metal-deficient stars formed. Under this assumption, we find that this primordial metal abundance pattern has profound consequences for the thermal balance and chemical composition of the gas, and hence for the EOS of the parental cloud. The polytopic EOS is soft for low, [O/H]10^{-2} due to the large opacity in the CO and H2O cooling lines. It is further found that a regulating role is played by the presence and temperature of the dust, even when the overall carbon abundance is only [C/H]~10^{-2}. When the dust is warmer than the gas, a region with gamma~1.2 results around a density of ~10^4 cm^{-3}. When the dust is colder than the gas, a region with gamma~0.8 is found for a density of ~10^6 cm^{-3}. Implications for the primordial initial mass function (IMF) as well as the IMF in starburst galaxies, where the metallicity is super-solar, are explored and related to processes that influence the temperature of the ambient dust.
Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Kirbie, Hugh C. (Los Alamos, NM)
2007-02-06
A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).
NASA Astrophysics Data System (ADS)
Armstrong, E.; Frenje, J.; Gatu Johnson, M.; Li, C. K.; Rinderknecht, H.; Rosenberg, M.; Seguin, F. H.; Sio, H.; Zylstra, A.; Petrasso, R. D.
2014-10-01
A compact ``Orange'' Spectrometer is being designed for measurements of alpha and proton spectra in the range of ~ 1-5 MeV, produced in low-yield 3He3He experiments at the OMEGA laser and at the National Ignition Facility (NIF). Particle ray-tracing through magnetic fields, modeled by COMSOL, were conducted with the code Python. The goal is to identify an optimal setup for a spectrometer to measure alpha particles at relatively low energies and at low yield. Ability to study the alpha particles in addition to the protons is essential for understanding the nuclear physics governing the final-state interactions between pairs of particles in the three-body final state. This work was supported in part by the U.S. DOE and NLUF.
NASA Astrophysics Data System (ADS)
Saini, Seema; Kumar, Sunil; Lal, A. K.
2015-06-01
A method is proposed to compute the eigenfrequencies of small adiabatic pseudo-radial modes of oscillations of differentially rotating and tidally distorted stellar models by taking into account the effect of mass variations on its equipotential surface inside the stars. The developed approach has been used to compute certain radial modes of oscillations of polytropic models with polytropic indices 1.5, 3.0 and 4.0. The results obtained have been compared with results obtained earlier without taking into account the mass variation. Certain conclusions based on this study have been drawn.
Goncharov, P. R.; Ozaki, T.; Sudo, S.; Tamura, N.; Veshchev, E. A.; Sergeev, V. Yu.; Krasilnikov, A. V.
2006-10-15
Experiments on suprathermal ion physics are carried out on the Large Helical Device (LHD) with a 40 channel compact neutral particle analyzer (CNPA). The analyzer is used both in passive nonperturbing chord-integral neutral particle flux measurements and for local probing with an impurity pellet. The analyzer observes trapped particles with vertical bar v{sub parallel}/v vertical bar <0.25 and the pitch angle cosine value v{sub parallel}/v changes sign along the diagnostic sight line. The measurable energy range for H{sup 0} is 1-170 keV. Radially resolved data on local H{sup 0} atomic energy spectra have been obtained on LHD by the pellet charge exchange method with CNPA, as well as chord-integral atomic energy distribution data for electron cyclotron heated, neutral beam injected, and high power ion cyclotron heated plasma. The article addresses the diagnostic technical background and the analysis scheme of measurement results taking into account the helical geometry and the species and densities of the charge exchange targets.
Mohammed Khaleduzzaman; Joseph Francis; Meryll E. Corbin; Elizabeth McIlwain; Marc Boudreaux; Min Du; Tim W. Morgan; Karin E. Peterson
2007-01-01
Viral infections of the heart are a causative factor of myocarditis as well as of sudden, unexpected deaths of children, yet the mechanisms of pathogenesis remain unclear, in part due to the relatively few animal models of virus-induced myocarditis. In the current study, we examined the ability of polytropic murine retroviruses to infect the heart and induce cardiac dysfunction. In
On the determination of electron polytrope indices within coronal mass ejections in the solar wind
Gosling, J.T. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
1999-09-01
Electron temperature and density often appear to be negatively correlated with one another as a coronal mass ejection, CME, in the solar wind passes over a spacecraft at 1 AU and beyond. It has been suggested that this negative correlation within magnetic clouds, which form a subset of all CMEs, implies that the electron polytropic index for the plasma within the clouds is significantly less than 1.0. We argue that single-point measurements of density and temperature within clouds do not speak to the issue of the coupled evolution of density and temperature that occurs as the clouds expand out into the heliosphere, and thus do not provide a measure of the polytropic index within them. Moreover, we show that observed electron temperatures within magnetic clouds and CMEs close to the Sun, at 1 AU, and at large heliocentric distances do not agree with predictions based upon electron polytropic indices significantly less than 1.0. We suggest that the negative correlation between electron temperature and density often observed within CMEs and magnetic clouds at 1 AU and beyond simply reflects the presence of structure within the CMEs and the plasma{close_quote}s tendency to achieve local pressure balance as it evolves outward from the Sun. Our results indicate that self-similar models that require the electron polytrope index to be less than 1.0 in order for a magnetic cloud to expand are physically unrealistic. {copyright} 1999 American Geophysical Union
Models of universe with a polytropic equation of state: I. The early universe
NASA Astrophysics Data System (ADS)
Chavanis, Pierre-Henri
2014-02-01
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.
Polytropic transonic galactic outflows in a dark matter halo with a central black hole
Igarashi, Asuka; Nitta, Shin-ya
2015-01-01
Polytropic transonic solutions of spherically symmetric and steady galactic winds in the gravitational potential of a dark matter halo (DMH) with a supermassive black hole (SMBH) are studied. The solutions are classified in terms of their topological features, and the gravitational potential of the SMBH adds a new branch to the transonic solutions generated by the gravity of the DMH. The topological types of the transonic solutions depend on the mass distribution, the amount of supplied energy, the polytropic index $\\gamma$, and the slope $\\alpha$ of the DMH mass distribution. When $\\alpha$ becomes larger than a critical value $\\alpha_\\mathrm{c}$, the transonic solution types change dramatically. Further, our model predicts that it is possible for a slowly accelerating outflow to exist, even in quiescent galaxies with small $\\gamma$. This slowly accelerating outflow differs from those considered in many of the previous studies focusing on supersonic outflows in active star-forming galaxies. In addition, our m...
Investigation of the quadrupole vibrations of the sun by means of multizonal polytropic models
NASA Astrophysics Data System (ADS)
Gavryuseva, E. A.; Kopysov, Y. S.
1981-06-01
One-, two-, and three-zone polytropic models are used to study the quadrupole vibrations of the sun. Conditions are found under which vibrations of gravitational type are localized in the central region of a star. It is shown that oscillations with a period of 2 h 40 min can be the fundamental tone of core vibrations and one of the higher g-modes of the sun as a whole. The mechanism for the observed reduction in solar diameter is examined.
Polytropic thin-shell collapse in non-commutative d-dimensional Reissner-Nordström geometry
NASA Astrophysics Data System (ADS)
Sharif, M.; Iftikhar, Sehrish
2015-04-01
We study thin-shell collapse in non-commutative d-dimensional Reissner-Nordström geometry with most general polytropic equation of state. We formulate equation of motion for the shell using Israel junction conditions and express it in terms of non-commutative factor through smeared Gaussian distribution. It is found that non-commutative collapsing thin-shell in the presence of extra dimensions leads to the formation of either a black hole or naked singularity.
Lin, Min-Kai
2012-07-20
Numerical calculations of the linear Rossby wave instability (RWI) in global three-dimensional (3D) disks are presented. The linearized fluid equations are solved for vertically stratified, radially structured disks with either a locally isothermal or polytropic equation of state, by decomposing the vertical dependence of the perturbed hydrodynamic quantities into Hermite and Gegenbauer polynomials, respectively. It is confirmed that the RWI operates in 3D. For perturbations with vertical dependence assumed above, there is little difference in growth rates between 3D and two-dimensional (2D) calculations. Comparison between 2D and 3D solutions of this type suggests the RWI is predominantly a 2D instability and that 3D effects, such as vertical motion, can be interpreted as a perturbative consequence of the dominant 2D flow. The vertical flow around corotation, where vortex formation is expected, is examined. In locally isothermal disks, the expected vortex center remains in approximate vertical hydrostatic equilibrium. For polytropic disks, the vortex center has positive vertical velocity, whose magnitude increases with decreasing polytropic index n.
NASA Technical Reports Server (NTRS)
Totten, T. L.; Freeman, J. W.; Arya, S.
1995-01-01
Observations of solar wind proton temperatures indicate that the solar wind is heated as it moves outward toward the orbit of Earth. This heating, which may be the results of electron heat conduction and perhaps MHD waves, has proven difficult to quantify and hence is often neglected in MHD models of the solar wind. An alternate approach to finding explicit heating terms for the MHD energy equation is to use a polytropic approximation. This paper discusses the properties of the polytropic approximation and its application to the solar wind plasma. By using data from the Helios 1 spacecraft, an empirical value for the polytropic index of the free-streaming solar wind is determined. Various corrections to the data are made to account for velocity, nonuniformity in radial sampling, and stream interaction regions. The polytropic index, as derived from proton data, is found to indepedent of speed state, within statistical error, and has an average value of 1.46. If magnetic pressure is included, the polytropic index has an average value of 1.58.
NASA Technical Reports Server (NTRS)
Lerche, I.; Low, B. C.
1980-01-01
Exact analytic solutions for the static equilibrium of a gravitating plasma polytrope in the presence of magnetic fields are presented. The means of generating various equilibrium configurations to illustrate directly the complex physical relationships between pressure, magnetic fields, and gravity in self-gravitating systems is demonstrated. One of the solutions is used to model interstellar clouds suspended by magnetic fields against the galactic gravity such as may be formed by the Parker (1966) instability. It is concluded that the pinching effect of closed loops of magnetic fields in the clouds may be a dominant agent in further collapsing the clouds following their formation.
Gregory Gabadadze; Rachel A. Rosen
2007-08-24
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.
Radiative Transfer Effects on the Stability of Sound Waves in a Polytropic Atmosphere
NASA Astrophysics Data System (ADS)
MacDonald, James; Mullan, Dermott
1997-05-01
From a perturbation analysis of the boundary value problem that describes the behavior of optically thin disturbances to a polytropic atmosphere initially in hydrostatic and radiative equilibrium, we derive criteria for the overstability of acoustic modes. Our criteria are more general than those found by Spiegel, which are strictly valid only if the radiative cooling time is uniform over the atmosphere, i.e., if the polytropic index m = 6. Our criteria for overstability are valid for any value of m. Applying our results to the Sun and giant stars, we find that sound waves in the envelope of the Sun do not appear to be unstable but that instability may occur in the envelopes of red giants. We note that, if acoustic waves become overstable as a star evolves into a giant, then the acoustic power in the envelopes of cool giants will be greater than one would have expected on the basis of the predictions of Lighthill theory. We propose that chromospheric heating in nonmagnetic stars (such as old giants in globular clusters) contains a significant component that arises from acoustic overstability.
GRMHD Simulations of Binary Neutron Star Mergers with Piecewise Polytropic Equations of State
NASA Astrophysics Data System (ADS)
Giacomazzo, Bruno
2015-04-01
We present new results of fully general relativistic magnetohydrodynamic (GRMHD) simulations of binary neutron star (BNS) mergers performed with the Whisky code. Our new simulations consider both equal and unequal-mass systems and describe the NS matter via piecewise polytropic equations of state (EOSs). BNS mergers are powerful sources of gravitational waves (GWs) that can be detected by ground based detectors, such as advanced Virgo and LIGO, and they are also thought to be behind the central engine powering short gamma-ray bursts. In our simulations we therefore focus both on the GW emission and on the dynamics of matter and magnetic fields, both in the case a black hole is promptly formed and in the case of the formation of a long-lived magnetized NS. Since the EOS has an important role in both GW emission and matter dynamics, our simulations employ piecewise polytropic EOSs composed by seven pieces, four for the low-density regions (including the crust) and three for the core, in order to more accurately match physically motivated EOSs. Thermal effects are also included in order to more properly describe the post-merger dynamics.
D. Reese; F. Lignières; M. Rieutord
2006-09-26
Context: With the launch of space missions devoted to asteroseismology (like COROT), the scientific community will soon have accurate measurements of pulsation frequencies in many rapidly rotating stars. Aims: The present work focuses on the effects of rotation on pulsations of rapidly rotating stars when both the Coriolis and centrifugal accelerations require a non-perturbative treatment. Method: We develop a 2-dimensional spectral numerical approach which allows us to compute acoustic modes in centrifugally distorted polytropes including the full influence of the Coriolis force. This method is validated through comparisons with previous studies, and the results are shown to be highly accurate. Results: In the frequency range considered and with COROT's accuracy, we establish a domain of validity for perturbative methods, thus showing the need for complete calculations beyond v.sin i = 50 km/s for a R = 2.3 R_\\odot, M = 1.9 M_\\odot polytropic star. Furthermore, it is shown that the main differences between complete and perturbative calculations come essentially from the centrifugal distortion.
Reese, D; Rieutord, M
2006-01-01
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 c...
Compact monolithic capacitive discharge unit
Roesler, Alexander W. (Tijeras, NM); Vernon, George E. (Rio Rancho, NM); Hoke, Darren A. (Albuquerque, NM); De Marquis, Virginia K. (Tijeras, NM); Harris, Steven M. (Albuquerque, NM)
2007-06-26
A compact monolithic capacitive discharge unit (CDU) is disclosed in which a thyristor switch and a flyback charging circuit are both sandwiched about a ceramic energy storage capacitor. The result is a compact rugged assembly which provides a low-inductance current discharge path. The flyback charging circuit preferably includes a low-temperature co-fired ceramic transformer. The CDU can further include one or more ceramic substrates for enclosing the thyristor switch and for holding various passive components used in the flyback charging circuit. A load such as a detonator can also be attached directly to the CDU.
NASA Astrophysics Data System (ADS)
Yamamoto, Takao; Miyake, Masataka; Miura-Mattausch, Mitiko
2013-04-01
We have developed a compact model of the injection-enhanced insulated-gate bipolar transistor (IGBT) applicable for circuit optimization. The main development is modeling the hole accumulation in the floating-base region. It is demonstrated that the observed negative gate capacitance is well reproduced with the developed model.
Relativistic self-similar dynamic collapses of black holes in general polytropic spherical clouds
NASA Astrophysics Data System (ADS)
Lian, Biao; Lou, Yu-Qing
2014-02-01
We study the hydrodynamic self-similar mass collapses of general polytropic (GP) spherical clouds to central Schwarzschild black holes and void evolution with or without shocks. In order to grossly capture characteristic effects of general relativity outside yet close to the event horizon of a Schwarzschild black hole and to avoid mathematical complexity, we adopt the approximation of the Paczynski-Wiita gravity to replace the simple Newtonian gravity in our model formulation. A new dimensionless parameter s appears with the physical meaning of the square of the ratio of the sound speed to the speed of light c. Various self-similar dynamic solutions are constructed for a polytropic index ? > 4/3. Two (for small enough s < 1) or no (for large enough s < 1) expansion-wave collapse solutions with central event horizons exist when ? > 4/3, representing the collapse of static singular GP spheres towards the central singularity of space-time. Such GP spherical dynamic mass collapse is shown to be highly efficient for the rapid formation of supermassive black holes (mass range of ˜106-1010 M?) in the early Universe or even hypermassive black holes (mass range of ˜1010-1012 M?) if extremely massive mass reservoirs could be sustained for a sufficiently long time, which may evolve into hard X-ray/gamma-ray sources or quasars according to their surroundings. Self-similar dynamic solutions of a GP gas are also proposed for the stellar mass black hole formation during the violent supernova explosion of a massive progenitor star, the time-scale of which is estimated of ˜10-3 s. Rebound shocks travelling in supernovae are also discussed based on our self-similar shock expansion solutions.
Hydrodynamics of binary coalescence. 2: Polytropes with gamma = 5/3
NASA Technical Reports Server (NTRS)
Rasio, Frederic A.; Shapiro, Stuart L.
1995-01-01
We present a new numerical study of the equilibrium and stability properties of close binary systems. We use the smoothed-particle hydrodynamics (SPH) technique both to construct accurate equilibrium configurations in three dimensions and to follow their hydrodynamic evolution. We adopt a simple polytropic equation of state p = K(sub rho)(exp gamma) with gamma = 5/3 and K = constant within each star, applicable to low-mass degenerate dwarfs as well as low-mass main-sequence stars. For degenerate configurations, we set the two polytropic constants equal, K = K prime, independent of the mass ratio. For main-sequence stars, we adjust K and K prime so as to obtain a simple mass-radius relation of the form R/R prime = M/M prime, where R prime and M prime are the radius and mass of the secondary. Along a sequence of binary equilibrium configurations for two identical stars, we demonstrate the existence of both secular and dynamical instabilities, confirming directly the results of recent analytic work. We use the SPH method to calculate the nonlinear development of the dynamical instability and to determine the final fate of the system. We find that the two stars merge together into a single, rapidly rotating object in just a few orbital periods. Equilibrium sequences are also constructed for systems containing two nonidentical stars. These sequences terminate at a Roche limit, which we can determine very accurately using SPH. For two low-mass main-sequence stars with mass ratio q approximately less than 0.4 we find that the (synchronized) Roche limit configuration is secularly unstable. We discuss the implications of our results for the evolution of double white-dwarf systems and W Ursae Majoris binaries.
Harland, C J; Clark, T D; Peters, N S; Everitt, M J; Stiffell, P B
2005-12-01
Conventional electrocardiogram (ECG) systems make use of separate electrical connections to the arms and legs. These use a 'long baseline' for the voltage reference potential which in the case of precordial ECG leads is provided using a Wilson central terminal (WCT) wiring configuration. The aims of this project were (a) to construct compact, non-invasive surface ECG sensor arrays which would operate without the need for a WCT reference, (b) to obtain high quality precordial ECGs showing fine differences in ECG detail between small adjacent areas of the chest and (c) to reconstruct, from a compact array of four sensors, ECGs which closely match to the conventional 7-lead ECG system, but without the need for multiple wires and long baselines. In this paper, we describe two sensor array configurations which have been constructed using electric potential sensors (EPSs). We show high quality precordial ECGs obtained from small areas of the surface of the chest and show the different angular vectors (leads) in the frontal cardiac plane constructed using signals from the array elements. We suggest that these ECG arrays, which are simple to apply, should prove to be a valuable tool in providing useful information about the state of the heart. PMID:16311443
Compaction managed mirror bend achromat
Douglas, David (Yorktown, VA)
2005-10-18
A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.
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....
NASA Technical Reports Server (NTRS)
Sittler, E. C., Jr.; Scudder, J. D.
1979-01-01
Empirical evidence is presented that solar wind thermal electrons obey a polytrope law with polytrope index gamma = 1.175 plus or minus 0.03. The Voyager 2 and Mariner 10 data used as evidence are compared and discussed. The theoretical predictions that solar wind thermal electrons in the asymptotic solar wind should obey a polytrope law with polytrope index gamma = 1.16 plus or minus. The widespread impressions in the literature that solar wind electrons behave more like an isothermal than adiabatic gas, and the arguments that Coulomb collisions are the dominant stochastic process shaping observed electron distribution functions in the solar wind are reexamined, reviewed and evaluated. The assignment of the interplanetary potential as equal to approximately seven times the temperature of the thermal electrons is discussed.
Schmitt, Michael Houston
The ratio of positive to negative charges in the secondary cosmic muon flux is measured at the Compact Muon Solenoid experiment. Muons with momenta between 5 GeV/c and 1 TeV/c are observed in data collected at ground level or 89 m underground; and found to be a constant 1.2766 +/- 0.0032 (stat.) +/- 0.0032 (syst.) for momenta below 100 GeV/c, and rising with higher momenta. The fraction of charged pions and kaons in the secondary cosmic flux resulting in positive muon production has been estimated, with the fraction for pions = 0.553 +/- 0.005 and for kaons = 0.66 +/- 0.06, respectively. The results presented herein are in good agreement with cosmic ray shower models, consistent with previous measurements, and represent the most precise measurement to date for atmospheric muons up to 500 GeV/c. This is also the first physics measurement involving muons at the completed CMS detector.
Hydrodynamics of binary coalescence. 1: Polytropes with stiff equations of state
NASA Technical Reports Server (NTRS)
Rasio, Frederic A.; Shapiro, Stuart L.
1994-01-01
We performed a series of three-dimensional hydrodynamic calculations of binary coalescence using the smoothed particle hydrodynamics (SPH) method. The initial conditions are exact polytropic equilibrium configurations on the verge of dynamical instability. We consider synchronized equilbria only and concentrate on stiff equations of state, with adiabatic Gamma greater than 5/3. We assume that the polytropic constants (K identically equal to P/(rho(exp Gamma)) are the same for both components. These conditions apply well to models of neutron star binaries. Accordingly, we discuss our results in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO) project, and we calculate the emission of gravitational radiation in the quadruple approximation. The fully nonlinear development of the instability is followed using SPH until a new equilibrium configuration is reached by the system. We find that the properties of this final configuration depend sensitively on both the compressibility and mass ratio. An axisymmetric merged configuration is always produced when the adiabatic exponent Gamma approximately less than 2.3. As a consequence, the emission of gravitational radiation shuts off abruptly right after the onset of dynamical instability. In contrast, triaxial merged configurations are obtained when Gamma approximately greater than 2.3, and the system continues to emit gravitational waves after the final coalescence. Systems with mass ratios q not equal to 1 typically become dynamically unstable before the onset of mass transfer. Stable mass transfer from one neutron star to another in a close binary is therefore probably ruled out. For a mass ratio q approximately less than 0.5, however, dynamical mass transfer can temporarily retard the coalescence by causing a rapid reexpansion of the binary into a new, slightly eccentric but dynamically stable orbit. The maximum amplitude h(sub max) and peak luminosity L(sub max) of the gravitational waves emitted during the final coalescence are nearly independent of Gamma, but depend sensitively on the mass ratio q. The approximate scalings we find are h(sub max) varies as q(exp 2) and L(sub max) varies as q(exp 6) for q close to unity.
NASA Technical Reports Server (NTRS)
Riley, Pete; Gosling, J. T.; Pizzo, V. J.
2001-01-01
Single-point spacecraft measurements within coronal mass ejections (CMEs) often exhibit a negative correlation between electron density and temperature. At least two opposing interpretations have been suggested for this relationship. If, on one hand, these single spacecraft observations provide direct measures of the polytropic properties of the plasma, then they imply that the polytropic index for the electrons gamma(sub e) is often < 1. Moreover, since the electrons carry the bulk of the pressure (via their significantly higher temperature), this further implies that the dynamics of CME evolution are dominated by an effective polytropic index gamma(sub e)ff < 1. On the other hand, gamma < 1 implies that as the ejecta propagate away from the Sun and expand, they also heat up; a result clearly at odds with in situ observations. In contrast to these CME intervals, many studies have shown that the quiescent solar wind exhibits a positive correlation between electron density and temperature, suggesting that gamma(sub e) > 1. In this study we simulate the evolution of a variety of CME-like disturbances in the solar wind using a one-dimensional, single-fluid model, to address the interpretation of the relationship between electron density and temperature within CMEs at fixed locations in space. Although we strictly impose a polytropic relationship (with gamma = constant) throughout our simulations, we demonstrate that a variety of correlations can exist between density and temperature at fixed points. Furthermore, we demonstrate that the presence of only local uncorrelated random fluctuations in density and temperature can produce a negative correlation. Consequently, we conclude that these single-point observations of negative correlations between electron density and temperature cannot be used to infer the value of gamma(sub e). Instead, we suggest that entropy variations, together with the plasma's tendency to achieve pressure balance with its surroundings, are responsible for the observed profiles.
NASA Astrophysics Data System (ADS)
Prajapati, R. P.; Chhajlani, R. K.
2010-11-01
The effect of pressure anisotropy and flow velocity on the Kelvin-Helmholtz (KH) instability of two magnetized anisotropic pressure plasmas flowing relative to each other is investigated using generalized polytrope laws. The anisotropic pressure with the generalized polytrope laws is considered with three-dimensional perturbations in the description of plasma using relevant magnetohydrodynamic (MHD) set of equations. The magnetic field is assumed in the x-direction and parallel to the direction of the flow of plasma streams. A complete polytrope model is given for the considered system in terms of pressure components, magnetic field, and density of the fluids to discuss the condition of KH instability, stability, and overstability. The problem is solved using the normal mode analysis and the general dispersion relation is obtained by applying the appropriate boundary conditions. The case of nonvanishing wavenumber transverse to the direction of the stream is obtained, which represents the stationery configuration without excitation of KH instability. The longitudinal mode of propagation is discussed with conditions of KH instability, stability, and overstability for collisionless (anisotropic) double-adiabatic Chew-Goldberger-Low (CGL) and collisional (isotropic) MHD media, depending on various values of polytrope indices. The effects of pressure anisotropy, different flow velocities, and magnetic field are also discussed on the growth rate of KH instability. We observe that the presence of flow velocity and pressure anisotropy of the plasmas has a destabilizing influence on the growth rate of the system. The growth rate is found larger for MHD set of equations in comparison to the CGL set of equations. The presence of magnetic field has a stabilizing role on the growth rate of the considered system.
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.
NASA Astrophysics Data System (ADS)
Klapp, J.; Cervantes-Cota, J.; Chauvet, P.
1990-11-01
RESUMEN. A nivel cosmol6gico pensamos que se ha estado prodticiendo radiaci6n gravitacional en cantidades considerables dentro de las galaxias. Si los eventos prodnctores de radiaci6n gravitatoria han venido ocurriendo desde Ia epoca de Ia formaci6n de las galaxias, cuando menos, sus efectos cosmol6gicos pueden ser tomados en cuenta con simplicidad y elegancia al representar la producci6n de radiaci6n y, por consiguiente, su interacci6n con materia ordinaria fenomenol6gicamente a trave's de una ecuaci6n de estado politr6pica, como lo hemos mostrado en otros trabajos. Presentamos en este articulo resultados nunericos de este modelo. ABSTRACT A common believe in cosmology is that gravitational radiation in considerable quantities is being produced within the galaxies. Ifgravitational radiation production has been running since the galaxy formation epoch, at least, its cosmological effects can be assesed with simplicity and elegance by representing the production of radiation and, therefore, its interaction with ordinary matter phenomenologically through a polytropic equation of state as shown already elsewhere. We present in this paper the numerical results of such a model. K words: COSMOLOGY - GRAVITATION
Acoustic oscillations in rapidly rotating polytropic stars I. Effects of the centrifugal distortion
F. Lignieres; M. Rieutord; D. Reese
2006-04-13
A new non-perturbative method to compute accurate oscillation modes in rapidly rotating stars is presented. In this paper, the effect of the centrifugal force is fully taken into account while the Coriolis force is neglected. This assumption is valid when the time scale of the oscillation is much shorter than the inverse of the rotation rate and is expected to be suitable for high radial order p-modes of $\\delta$ Scuti stars. Axisymmetric p-modes have been computed in uniformly rotating polytropic models of stars. In the frequency and rotation range considered, we found that as rotation increases (i) the asymptotic structure of the non-rotating frequency spectrum is first destroyed then replaced by a new form of organization (ii) the mode amplitude tends to concentrate near the equator (iii) differences with perturbative methods become significant as soon as the rotation rate exceeds about fifteen percent of the Keplerian limit. The implications for the seismology of rapidly rotating stars are then discussed.
Acoustic oscillations in rapidly rotating polytropic stars I. Effects of the centrifugal distortion
Lignières, F; Rieutord, M
2006-01-01
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.
Cracking of compact objects with electromagnetic field
NASA Astrophysics Data System (ADS)
Azam, M.; Mardan, S. A.; Rehman, M. A.
2015-09-01
In this paper, we investigate the role of electromagnetic field on the stability regions of charged self-gravitating compact objects by using the concept of cracking. For this purpose, we have applied local density perturbation scheme to the hydrostatic equilibrium equation as well as on physical parameters involved in the model. In particular, we have examined the cracking of charged compact objects like PSR J1614-2230, PSR J1903+327, Vela X-1, SMC X-1 and Cen X-3 with different values of charge. We conclude that these objects exhibit cracking and stability regions decreases with the increase of charge.
Suyama, M.; Kawai, Y.; Kimura, S. [Hamamatsu Photonics K.K., Shizuoka (Japan)] [and others
1996-12-31
In order to be utilized in such application fields as high energy physics or medical imaging, where a huge number of photodetectors are assembled in designated small area, the world`s smallest HPD, the compact BFD, has been developed. The overall diameter and the length of the tube are 16mm and 15mm, respectively. The effective photocathode area is 8mm in diameter. At applied voltage of -8kV to the photocathode, the electron multiplication gain of a PD incorporated HPD (PD-BPD) is 1,600, and that of an APD (APD-BPD) is 65,000. In the pulse height distribution measurement, photoelectron peaks up to 6 photoelectrons are clearly distinguishable with the APD-BPD. Experiments established that there was no degradation of gain in magnetic fields up to 1.5T, an important performance characteristic of the compact BPD for application in high energy physics.
Kim, Jeong-Gyu; Kim, Woong-Tae; Seo, Young Min; Hong, Seung Soo E-mail: wkim@astro.snu.ac.kr E-mail: sshong@astro.snu.ac.kr
2012-12-20
We investigate the gravitational instability (GI) of rotating, vertically stratified, pressure-confined, polytropic gas disks using a linear stability analysis as well as analytic approximations. The disks are initially in vertical hydrostatic equilibrium and bounded by a constant external pressure. We find that the GI of a pressure-confined disk is in general a mixed mode of the conventional Jeans and distortional instabilities, and is thus an unstable version of acoustic-surface-gravity waves. The Jeans mode dominates in weakly confined disks or disks with rigid boundaries. On the other hand, when the disk has free boundaries and is strongly pressure confined, the mixed GI is dominated by the distortional mode that is surface-gravity waves driven unstable under their own gravity and thus incompressible. We demonstrate that the Jeans mode is gravity-modified acoustic waves rather than inertial waves and that inertial waves are almost unaffected by self-gravity. We derive an analytic expression for the effective sound speed c{sub eff} of acoustic-surface-gravity waves. We also find expressions for the gravity reduction factors relative to a razor-thin counterpart that are appropriate for the Jeans and distortional modes. The usual razor-thin dispersion relation, after correcting for c{sub eff} and the reduction factors, closely matches the numerical results obtained by solving a full set of linearized equations. The effective sound speed generalizes the Toomre stability parameter of the Jeans mode to allow for the mixed GI of vertically stratified, pressure-confined disks.
Furth
1980-01-01
The objective of the compact torus approach is to provide toroidal magnetic-field configurations that are based primarily on plasma currents and can be freed from closely surrounding mechanical structures. Some familiar examples are the current-carrying plasma rings of reversed-field theta pinches and relativistic-electron smoke ring experiments. The spheromak concept adds an internal toroidal magnetic field component, in order to enhance
H. P. Furth
1981-01-01
The objective of the compact torus approach is to provide toroidal magnetic-field configurations that are based primarily on plasma currents and can be freed from closely surrounding mechanical structures. Some familiar examples are the current-carrying plasma rings of reversed-field theta pinches and relativistic-electron ''smoke ring'' experiments. The spheromak concept adds an internal toroidal magnetic field component, in order to enhance
NASA Astrophysics Data System (ADS)
Totten, Tracy Lynn
Data from the Helios 1 spacecraft have been used to determine an empirical value for the polytropic index for the free-streaming solar wind. Application of this non-adiabatic polytropic index to a two-dimensional solar wind computer model to simulate the effects of thermal heat conduction has been investigated. The current project involves the insertion of this empirically-derived polytropic index into a magnetohydrodynamic model of solar wind propagation. This computer model is used to predict the time for shocks originating at the Sun to travel to Earth. This information is important for the protection of Earth-orbiting satellites. The model is a two and one-half-dimensional numerical code that solves the magnetohydrodynamic equations using the two-step Lax -Wendroff scheme. The shock jump ratios of the plasma parameters are determined using the Rankine-Hugoniot relations. In addition, the shock model requires a representative background solar wind as an initial condition. The original background solar wind is similar to the results obtained by Parker (Astrophysical Journal, 1958) and Weber and Davis (Astrophysical Journal, 1967). Changes to this initial condition are made by applying the non-adiabatic polytropic index to a three-dimensional, steady-state, magnetohydrodynamic model of the solar wind. The adjustments to the steady -state model produce a background solar wind that compares well to Helios 1 data. This new background solar wind is used as the initial condition for the 2D shock model. The shock model is also adjusted to include the effects of heat conduction. Comparison of model results with observational data indicate that these changes produce average transit times that are only 45 minutes late. Before the changes to the 2D shock model and its initial solar wind condition were made, the average prediction time was two hours late. Adjusting the shock model to include the effects of heat conduction but using the original background solar wind produces an average transit time that is less than one hour early. A few specific events are discussed in greater detail.
NASA Technical Reports Server (NTRS)
Osherovich, Vladimir A.; Fainberg, J.; Stone, R. G.; MacDowall, R. J.; Berdichevsky, D.
1997-01-01
A self similar model for the expanding flux rope is developed for a magnetohydrodynamic model of interplanetary magnetic clouds. It is suggested that the dependence of the maximum magnetic field on the distance from the sun and the polytropic index gamma has the form B = r exp (-1/gamma), and that the ratio of the electron temperature to the proton temperature increases with distance from the sun. It is deduced that ion acoustic waves should be observed in the cloud. Both predictions were confirmed by Ulysses observations of a 1993 magnetic cloud. Measurements of gamma inside the cloud demonstrate sensitivity to the internal topology of the magnetic field in the cloud.
NASA Astrophysics Data System (ADS)
Geroyannis, Vassilis S.; Karageorgopoulos, Vasileios G.
2015-08-01
We develop a “hybrid approximative scheme” in the framework of the post-Newtonian approximation for computing general-relativistic polytropic models simulating neutron stars in critical rigid rotation. We treat the differential equations governing such a model as a “complex initial value problem”, and we solve it by using the so-called “complex-plane strategy”. We incorporate into the computations the complete solution for the relativistic effects, this issue representing a significant improvement with regard to the classical post-Newtonian approximation, as verified by extended comparisons of the numerical results.
NASA Astrophysics Data System (ADS)
Tirani, M. D.; Maleki, M.; Kajani, M. T.
2014-11-01
A numerical method for solving the Lane-Emden equations of the polytropic index ? when 4.75 ? ? ? 5 is introduced. The method is based upon nonclassical Gauss-Radau collocation points and Freud type weights. Nonclassical orthogonal polynomials, nonclassical Radau points and weighted interpolation are introduced and are utilized in the interval [0,1]. A smooth, strictly monotonic transformation is used to map the infinite domain x ? [0,?) onto a half-open interval t ? [0,1). The resulting problem on the finite interval is then transcribed to a system of nonlinear algebraic equations using collocation. The method is easy to implement and yields very accurate results.
NASA Technical Reports Server (NTRS)
Title, A. M.; Gillespie, B. A.; Mosher, J. W.
1982-01-01
A compact magnetograph system based on solid Fabry-Perot interferometers as the spectral isolation elements was studied. The theory of operation of several Fabry-Perot systems, the suitability of various magnetic lines, signal levels expected for different modes of operation, and the optimal detector systems were investigated. The requirements that the lack of a polarization modulator placed upon the electronic signal chain was emphasized. The PLZT modulator was chosen as a satisfactory component with both high reliability and elatively low voltage requirements. Thermal control, line centering and velocity offset problems were solved by a Fabry-Perot configuration.
Linear stability analysis of nonaxisymmetric instabilities in self-gravitating polytropic disks
NASA Astrophysics Data System (ADS)
Hadley, Kathryn Z.
An important problem in astrophysics involves understanding the formation of planetary systems. When a star-forming cloud collapses under gravity its rotation causes it to flatten into a disk. Only a small percentage of the matter near the rotation axis falls inward to create the central object, yet our Sun contains over 99% of the matter of our Solar System. We examine how global hydrodynamic instabilities transport angular momentum through the disk causing material to accrete onto the central star. We analyze the stability of polytropic disks in the linear regime. A power law angular velocity of power q is imposed, and the equilibrium disk structure is found through solution of the time-independent hydrodynamic equations via the Hachisu self-consistent field method. The disk is perturbed, and the time-dependent linearized hydrodynamic equations are used to evolve it. If the system is unstable, the characteristic growth rate and frequency of the perturbation are calculated. We consider modes with azimuthal e im[varphi] dependence, where m is an integer and [varphi] is the azimuthal angle. We map trends across a wide parameter space by varying m , q and the ratios of the star-to-disk mass M* /Md and inner-to-outer disk radius r - /r + . We find that low m modes dominate for small r - /r + , increasing to higher r - /r + as M* /Md increases, independent of q . Three main realms of behavior are identified, for M* << Md , M* ? Md and M* >> Md , and analyzed with respect to the I, J and P mode types as discussed in the literature. Analysis shows that for M* << Md , small r - /r + disks are dominated by low m I modes, which give way to high m J modes at high r - /r + . Low m J modes dominate M* ? Md disks for small r - /r + , while higher m I modes dominate for high r - /r + . Behavior diverges with q for M* >> Md systems with high q models approximating M* ? Md characteristics, while low q models exhibit m = 2 I modes dominating where r - /r + < 0.60.
Viral RNAs Are Unusually Compact
Gopal, Ajaykumar; Egecioglu, Defne E.; Yoffe, Aron M.; Ben-Shaul, Avinoam; Rao, Ayala L. N.; Knobler, Charles M.; Gelbart, William M.
2014-01-01
A majority of viruses are composed of long single-stranded genomic RNA molecules encapsulated by protein shells with diameters of just a few tens of nanometers. We examine the extent to which these viral RNAs have evolved to be physically compact molecules to facilitate encapsulation. Measurements of equal-length viral, non-viral, coding and non-coding RNAs show viral RNAs to have among the smallest sizes in solution, i.e., the highest gel-electrophoretic mobilities and the smallest hydrodynamic radii. Using graph-theoretical analyses we demonstrate that their sizes correlate with the compactness of branching patterns in predicted secondary structure ensembles. The density of branching is determined by the number and relative positions of 3-helix junctions, and is highly sensitive to the presence of rare higher-order junctions with 4 or more helices. Compact branching arises from a preponderance of base pairing between nucleotides close to each other in the primary sequence. The density of branching represents a degree of freedom optimized by viral RNA genomes in response to the evolutionary pressure to be packaged reliably. Several families of viruses are analyzed to delineate the effects of capsid geometry, size and charge stabilization on the selective pressure for RNA compactness. Compact branching has important implications for RNA folding and viral assembly. PMID:25188030
18 CFR 420.23 - Exempt uses under the Compact.
Code of Federal Regulations, 2010 CFR
2010-04-01
...Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-WATER SUPPLY CHARGES Water Supply Policy § 420.23 Exempt uses under the Compact. (a) Section 15.1(b) of the Delaware...
NASA Technical Reports Server (NTRS)
Foster, John E. (Inventor)
2004-01-01
A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.
High-frequency behavior of w-mode pulsations of compact stars
Y. J. Zhang; J. Wu; P. T. Leung
2011-01-01
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.
On Intuitionistic Fuzzy ?-Almost Compactness and ?-Nearly Compactness
Renuka, R.; Seenivasan, V.
2015-01-01
The concept of intuitionistic fuzzy ?-almost compactness and intuitionistic fuzzy ?-nearly compactness in intuitionistic fuzzy topological spaces is introduced and studied. Besides giving characterizations of these spaces, we study some of their properties. Also, we investigate the behavior of intuitionistic fuzzy ?-compactness, intuitionistic fuzzy ?-almost compactness, and intuitionistic fuzzy ?-nearly compactness under several types of intuitionistic fuzzy continuous mappings. PMID:26236774
A compact low temperature scanning tunneling microscope
NASA Astrophysics Data System (ADS)
Gupta, Anjan Kumar; Sinha, Jaivardhan; Choudhary, Shyam Kumar; Singh, Udai Raj
2009-02-01
We describe the design and fabrication of a compact Low Temperature Scanning Tunneling Microscope (LT-STM) together with a dipper cryostat for cooling the STM down to liquid helium temperatures. The STM, based on the piezo-tube walker as coarse approach mechanism, is suspended inside a cryostat vacuum can using three soft helical springs. The can is dipped into a liquid helium storage container for cooling the STM. Its compact size makes it less susceptible to mechanical vibrations and so the STM works with atomic resolution with a simple spring suspension. We demonstrate the performance of this STM for atomic resolution imaging and tunneling spectroscopy by observing the 3 ×3 charge modulation and the energy gap in the Charge Density Wave (CDW) phase of 2H-NbSe2 at liquid helium temperatures.
C. Adam; P. Klimas; J. Sanchez-Guillen; A. Wereszczynski
2008-11-27
We investigate a version of the abelian Higgs model with a non-standard kinetic term (K field theory) in 2+1 dimensions. The existence of vortex type solutions with compact support (topological compactons) is established by a combination of analytical and numerical methods. This result demonstrates that the concept of compact solitons in K field theories can be extended to higher dimensions.
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...
Technology Transfer Automated Retrieval System (TEKTRAN)
During temporary droughts that often limit agricultural production, soil compaction can hinder plant roots from reaching depths of soil where moisture is available. Many fields exhibit various degrees of soil compaction, resulting from variable soil types and past tillage and traffic practices. Va...
Thermodynamics of magnetized binary compact objects
Uryu, Koji [Department of Physics, University of the Ryukyus, Senbaru, Nishihara, Okinawa 903-0213 (Japan); Gourgoulhon, Eric [Laboratoire Univers et Theories, UMR 8102 du CNRS, Observatoire de Paris, Universite Paris Diderot, F-92190 Meudon (France); Markakis, Charalampos [Department of Physics, University of Wisconsin-Milwaukee, Post Office Box 413, Milwaukee, Wisconsin 53201 (United States)
2010-11-15
Binary systems of compact objects with electromagnetic field are modeled by helically symmetric Einstein-Maxwell spacetimes with charged and magnetized perfect fluids. Previously derived thermodynamic laws for helically symmetric perfect-fluid spacetimes are extended to include the electromagnetic fields, and electric currents and charges; the first law is written as a relation between the change in the asymptotic Noether charge {delta}Q and the changes in the area and electric charge of black holes, and in the vorticity, baryon rest mass, entropy, charge and magnetic flux of the magnetized fluid. Using the conservation laws of the circulation of magnetized flow found by Bekenstein and Oron for the ideal magnetohydrodynamic fluid, and also for the flow with zero conducting current, we show that, for nearby equilibria that conserve the quantities mentioned above, the relation {delta}Q=0 is satisfied. We also discuss a formulation for computing numerical solutions of magnetized binary compact objects in equilibrium with emphasis on a first integral of the ideal magnetohydrodynamic-Euler equation.
Stabilization of compactible waste
Franz, E.M.; Heiser, J.H. III; Colombo, P.
1990-09-01
This report summarizes the results of series of experiments performed to determine the feasibility of stabilizing compacted or compactible waste with polymers. The need for this work arose from problems encountered at disposal sites attributed to the instability of this waste in disposal. These studies are part of an experimental program conducted at Brookhaven National Laboratory (BNL) investigating methods for the improved solidification/stabilization of DOE low-level wastes. The approach taken in this study was to perform a series of survey type experiments using various polymerization systems to find the most economical and practical method for further in-depth studies. Compactible dry bulk waste was stabilized with two different monomer systems: styrene-trimethylolpropane trimethacrylate (TMPTMA) and polyester-styrene, in laboratory-scale experiments. Stabilization was accomplished by wetting or soaking compactible waste (before or after compaction) with monomers, which were subsequently polymerized. Three stabilization methods are described. One involves the in-situ treatment of compacted waste with monomers in which a vacuum technique is used to introduce the binder into the waste. The second method involves the alternate placement and compaction of waste and binder into a disposal container. In the third method, the waste is treated before compaction by wetting the waste with the binder using a spraying technique. A series of samples stabilized at various binder-to-waste ratios were evaluated through water immersion and compression testing. Full-scale studies were conducted by stabilizing two 55-gallon drums of real compacted waste. The results of this preliminary study indicate that the integrity of compacted waste forms can be readily improved to ensure their long-term durability in disposal environments. 9 refs., 10 figs., 2 tabs.
DNA compaction by azobenzene-containing surfactant
Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Santer, Svetlana
2011-08-15
We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.
Multipolar universal relations between f -mode frequency and tidal deformability of compact stars
NASA Astrophysics Data System (ADS)
Chan, T. K.; Sham, Y.-H.; Leung, P. T.; Lin, L.-M.
2014-12-01
Though individual stellar parameters of compact stars usually demonstrate obvious dependence on the equation of state (EOS), EOS-insensitive universal formulas relating these parameters remarkably exist. In the present paper, we explore the interrelationship between two such formulas, namely the f -I relation connecting the f -mode quadrupole oscillation frequency ?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.
NASA Technical Reports Server (NTRS)
Hirschberg, J. G.
1979-01-01
Proposed monitor that detects back-reflected infrared radiation makes in situ turbidity measurements of lakes, streams, and other bodies of water. Monitor is compact, works well in daylight as at night, and is easily operated in rough seas.
Griffiths, Stewart
2003-09-30
The present invention provides compact geometries for the layout of microchannel columns through the use of turns and straight channel segments. These compact geometries permit the use of long separation or reaction columns on a small microchannel substrate or, equivalently, permit columns of a fixed length to occupy a smaller substrate area. The new geometries are based in part on mathematical analyses that provide the minimum turn radius for which column performance in not degraded. In particular, we find that straight channel segments of sufficient length reduce the required minimum turn radius, enabling compact channel layout when turns and straight segments are combined. The compact geometries are obtained by using turns and straight segments in overlapped or nested arrangements to form pleated or coiled columns.
Computational compact torus experiment
Eddleman, J.L.; McNamara, B.; Nash, J.K.; Shearer, J.W.; Turner, W.C.
1980-12-24
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.
Semi Compactness in Multiset Topology
J. Mahanta; D. Das
2014-11-21
In this paper, we introduce and study the concepts of semi open SOM) and semi closed (SCM) M-sets in multiset topological spaces.With this generalization of the notions of open and closed sets in M-topology, we generalize the concept of compactness in M-topology as semi compactness. Further semi compactness is generalized as semi whole compactness, semi partial whole compactness and semi full compactness. Some characterizations of these compact spaces are studied in the setting of multiset theory. In each step, several remarks with proper justifications are provided taking the well existing theories of general topology as the base of our study.
DNA compaction by a dendrimer.
Nandy, Bidisha; Maiti, Prabal K
2011-01-20
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
Physically detached 'compact groups'
NASA Technical Reports Server (NTRS)
Hernquist, Lars; Katz, Neal; Weinberg, David H.
1995-01-01
A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.
Zehfus, M H; Rose, G D
1986-09-23
An explicit measure of geometric compactness called the coefficient of compactness is introduced. This single value figure of merit identifies those continuous segments of the polypeptide chain having the smallest solvent-accessible surface area for their volume. These segments are the most compact units of the protein, and the larger ones correspond to conventional protein domains. To demonstrate the plausibility of this approach as a method of identifying protein domains, the measure is applied to lysozyme and ribonuclease to discover their constituent compact units. These units are then compared with domains, subdomains, and modules found by other methods. To show the sensitivity of the method, the measure is used to successfully differentiate between native and deliberately misfolded proteins [Novotný, J., Bruccoleri, R., & Karplus, M. (1984) J. Mol. Biol. 177, 787-818]. Methods that utilize only backbone atoms to define domains cannot distinguish between authentic and misfolded molecules because their backbone conformations are virtually superimposable. Compact units identified by this method exhibit a hierarchic organization. Such an organization suggests possible folding pathways that can be tested experimentally. PMID:3778881
S. Reucroft
2015-05-01
We investigate the hypothesis that the core of a galaxy has a positive electrical charge with an equal and opposite negative charge distributed over the galactic periphery. We present a determination of the amount of charge needed to explain the apparent anomalous rotation behaviour.
NASA Technical Reports Server (NTRS)
Gosling, J. T.; Riley, P.; Skoug, R. M.
2001-01-01
We strongly disagree with the essence of the Osherovich (hereafter Osherovich) comment on one of our papers. The following paragraphs provide the basis of our disagreement and elaborate on why we believe that none of the concluding statements in his Comment are true. Our most important point is that one can apply the model developed by Osherovich and colleagues to real data obtained at a single point in space to determine the polytropic index within magnetic clouds if and only if the highly idealized assumptions of that model conform to physical reality. There is good reason to believe that those assumptions do not provide an accurate physical description of real magnetic clouds in the spherically expanding solar wind.
Tolos, Laura
2015-01-01
We investigate compact objects formed by dark matter admixed with ordinary matter made of neutron star matter and white dwarf material. We consider non-self annihilating dark matter with an equation-of-state given by an interacting Fermi gas. We find new stable solutions, dark compact planets, with Earth-like masses and radii from few Km to few hundred Km for weakly interacting dark matter. For the strongly interacting dark matter case, we obtain dark compact planets with Jupiter-like masses and radii of few hundred Km. These objects could be formed primordially and accrete white dwarf material subsequently. They could be detected by observing exoplanets with unusually small radii. Moreover, we find that the recently observed 2 ${\\rm M}_{\\odot}$ pulsars set limits on the amount of dark matter inside neutron stars which is, at most, $10^{-6}{\\rm M}_\\odot$.
Laura Tolos; Juergen Schaffner-Bielich
2015-07-29
We investigate compact objects formed by dark matter admixed with ordinary matter made of neutron star matter and white dwarf material. We consider non-self annihilating dark matter with an equation-of-state given by an interacting Fermi gas. We find new stable solutions, dark compact planets, with Earth-like masses and radii from few Km to few hundred Km for weakly interacting dark matter. For the strongly interacting dark matter case, we obtain dark compact planets with Jupiter-like masses and radii of few hundred Km. These objects could be formed primordially and accrete white dwarf material subsequently. They could be detected by observing exoplanets with unusually small radii. Moreover, we find that the recently observed 2 ${\\rm M}_{\\odot}$ pulsars set limits on the amount of dark matter inside neutron stars which is, at most, $10^{-6}{\\rm M}_\\odot$.
Comprehensive Compaction Monitoring System
of New Asphalt Pavement Do Road-User Charges Make Sense for Texas? More States Are Exploring Alternatives of New Asphalt Pavement 12 Do Road-User Charges Make Sense for Texas? More States Are Exploring of pavement materials in real time. #12;TEXAS TRANSPORTATION RESEARCHER 3 by Dennis Christiansen Agency
Compacting XML Data: Zhang, Dyreson, Dang Compacting XML Data
Dyreson, Curtis
Compacting XML Data: Zhang, Dyreson, Dang Compacting XML Data Shuohao Zhang, Curtis Dyreson and Zhe XML Data: Zhang, Dyreson, Dang Book Data Doubleday The Da Vinci Code: Zhang, Dyreson, Dang Same Data, Different Structure Doubleday The Da
Fracture of explosively compacted aluminum particles in a cylinder
NASA Astrophysics Data System (ADS)
Frost, David; Loiseau, Jason; Goroshin, Sam; Zhang, Fan; Milne, Alec; Longbottom, Aaron
2015-06-01
The explosive compaction, fracture and dispersal of aluminum particles contained within a cylinder have been investigated experimentally and computationally. The aluminum particles were weakly confined in a cardboard tube and surrounded a central cylindrical burster charge. The compaction and fracture of the particles are visualized with flash radiography and the subsequent fragment dispersal with high-speed photography. The aluminum fragments produced are much larger than the original aluminum particles and similar in shape to those generated from the explosive fracture of a solid aluminum cylinder, suggesting that the shock transmitted into the aluminum compacts the powder to near solid density. The casing of the burster explosive (plastic-, copper-, and un-cased charges were used) had little influence on the fragment size. The effect of an air gap between the burster and the aluminum particles was also investigated. The particle motion inferred from the radiographs is compared with the predictions of a multimaterial hydrocode.
NASA Astrophysics Data System (ADS)
Pérez Martínez, Aurora; González Felipe, Ricardo; Manreza Paret, Daryel
2015-01-01
The magnetized color flavor locked matter phase can be more stable than the unpaired phase, thus becoming the ground state inside neutron stars. In the presence of a strong magnetic field, there exist an anisotropy in the pressures. We estimate the mass-radius relation of magnetized compact stars taking into account the parallel and perpendicular (to the magnetic field) pressure components.
Limestone compaction: an enigma
Shinn, Eugene A.; Halley, Robert B.; Hudson, J. Harold; Lidz, Barbara H.
1977-01-01
Compression of an undisturbed carbonate sediment core under a pressure of 556 kg/cm2 produced a “rock” with sedimentary structures similar to typical ancient fine-grained limestones. Surprisingly, shells, foraminifera, and other fossils were not noticeably crushed, which indicates that absence of crushed fossils in ancient limestones can no longer be considered evidence that limestones do not compact.
Industrial Optimization Compact Course
Kirches, Christian
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
Takao Suyama
2005-03-08
We discuss condensations of closed string tachyons localized in compact spaces. Time evolution of an on-shell condensation is naturally related to the worldsheet RG flow. Some explicit tachyonic compactifications of Type II string theory is considered, and some of them are shown to decay into supersymmetric theories known as the little string theories.
Soil Compaction Investigation.
ERIC Educational Resources Information Center
Turski, Mark P.
1988-01-01
Describes a lab investigation designed to introduce students to soil compaction and help them to learn to design and adapt procedures that scientists use when they plan and conduct controlled investigations. Provided are objectives, a list of materials, procedures, and a sample student handout. (CW)
Compact ultradense matter impactors.
Rafelski, Johann; Labun, Lance; Birrell, Jeremiah
2013-03-15
We study interactions of meteorlike compact ultradense objects (CUDO), having nuclear or greater density, with Earth and other rocky bodies in the Solar System as a possible source of information about novel forms of matter. We study the energy loss in CUDO puncture of the body and discuss differences between regular matter and CUDO impacts. PMID:25166521
NASA Technical Reports Server (NTRS)
Starck, Thomas F.; Brennan, Andrew D.
1990-01-01
Compact resistance-welding pinch gun lets one operator do jobs formerly needing two workers. Light in weight and produces repeatable, high-quality weld joints. Welding-electrode head rotates for easy positioning. Lever at top of handle activates spring to pinch electrodes together at preset welding force. Button at bottom of handle activates welding current. Cables supply electrical power.
Compact, Integrated Photoelectron Linacs
NASA Astrophysics Data System (ADS)
Yu, David
2000-12-01
The innovative compact high energy iniector which has been developed by DULY Research Inc., will have wide scientific industrial and medical applications. The new photoelectron injector integrates the photocathode directly into a multicell linear accelerator with no drift space between the injector and the linac. By focusing the beam with solenoid or permanent magnets, and producing high current with low emittance, extremely high brightness is achieved. In addition to providing a small footprint and improved beam quality in an integrated structure, the compact system considerably simplifies external subsystems required to operate the photoelectron linac, including rf power transport, beam focusing, vacuum and cooling. The photoelectron linac employs an innovative Plane-Wave-Transformer (PWT) design, which provides strong cell-to-cell coupling, relaxes manufacturing tolerance and facilitates the attachment of external ports to the compact structure with minimal field interference. DULY Research Inc. under the support of the DOE Small Business Innovation Research (SBIR) program, has developed, constructed and installed a 20-MeV, S-band compact electron source at UCLA. DULY Research is also presently engaged in the development of an X-band photoelectron linear accelerator in another SBIR project. The higher frequency structure when completed will be approximately three times smaller, and capable of a beam brightness ten times higher than the S-band structure.
Conserved charges in the principal chiral model on a supergroup
NASA Astrophysics Data System (ADS)
Miller, Barry H.
2006-08-01
The classical principal chiral model in 1+1 dimensions with target space a compact Lie supergroup is investigated. It is shown how to construct a local conserved charge given an invariant tensor of the Lie superalgebra. We calculate the super-Poisson brackets of these currents and argue that they are finitely generated. We show how to derive an infinite number of local charges in involution. We demonstrate that these charges Poisson commute with the non-local charges of the model.
Progress in Compact Toroid Experiments
Dolan, Thomas James
2002-09-01
The term "compact toroids" as used here means spherical tokamaks, spheromaks, and field reversed configurations, but not reversed field pinches. There are about 17 compact toroid experiments under construction or operating, with approximate parameters listed in Table 1.
Electrical resistivity of compacted clays
Abu-Hassanein, Z.S. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering] [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering; Benson, C.H.; Blotz, L.R. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Civil and Environmental Engineering] [Univ. of Wisconsin, Madison, WI (United States). Dept. of Civil and Environmental Engineering
1996-05-01
Relationships between electrical resistivity, compaction conditions, hydraulic conductivity, and index properties are reported for ten soils that have been used for constructing compacted soil liners having low field-scale hydraulic conductivity (<1 {times} 10{sup {minus}9} m/s). The electrical resistivity of compacted clay is sensitive to compaction conditions, with lower electrical resistivity obtained for compaction at higher water content or greater compactive effort. A unique relationship exists between electrical resistivity and initial (as-compacted) saturation for each clay that is independent of compactive effort. A unique relationship between hydraulic conductivity and electrical resistivity exists for some, but not all soils. Electrical resistivity is also correlated with index properties. Soils with higher liquid limit or plasticity index, a greater percentage of fines or clay, or a smaller coarse fraction have lower electrical resistivity.
NASA Technical Reports Server (NTRS)
Minow, Joseph I.
2014-01-01
(1) High energy (>100keV) electrons penetrate spacecraft walls and accumulate in dielectrics or isolated conductors; (2) Threat environment is energetic electrons with sufficient flux to charge circuit boards, cable insulation, and ungrounded metal faster than charge can dissipate; (3) Accumulating charge density generates electric fields in excess of material breakdown strenght resulting in electrostatic discharge; and (4) System impact is material damage, discharge currents inside of spacecraft Faraday cage on or near critical circuitry, and RF noise.
Comparative study of asphalt concrete laboratory compaction methods to simulate field compaction
Ziauddin A Khan; Hamad I Al-Abdul Wahab; Ibrahim Asi; Rezqallah Ramadhan
1998-01-01
The main objective of this study was to compare different laboratory compaction methods to field compaction and to select the laboratory method that was similar or close in compaction to that of the field. The candidate compaction methods were: (a) Marshall Automatic Impact Compaction; (b) Marshall Manual Impact Compaction; (c) California Kneading Compaction; (d) Gyratory Shear Compaction (angle of gyration
Compact Coadjoint Orbits John Rawnsley
Rawnsley, John
Compact Coadjoint Orbits John Rawnsley Mathematics Institute University of Warwick Coventry CV4 7AL This note is a response to the question of "Which connected Lie groups have compact coadjoint orbits?" which answer is that they are the coadjoint orbits of a compact Lie group. But that is not completely true
NASA Astrophysics Data System (ADS)
Placidi, M.; Jung, J.-Y.; Ratti, A.; Sun, C.
2014-12-01
This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.
NASA Technical Reports Server (NTRS)
Morgan, Gene E.; Thomas, Clark S.
1991-01-01
Spot welder designed for bonding insulated metal strips together. Compact, measuring only about 33.5 cm in its largest linear dimension. Pinch welder clamps electrodes on weldments with strong, repeatable force. Compressed air supplied through fitting on one handle. Small switch on same handle starts welding process when operator presses it with trigger. Provides higher, more repeatable clamping force than manually driven gun and thus produces weld joints of higher quality. Light in weight and therefore positioned precisely by operator.
Physics of Compact Stellarators
NASA Astrophysics Data System (ADS)
Hirshman, S.
1998-11-01
Recent progress in the design and theoretical understanding of compact stellarators will be described. Interest in compact stellarators, for which the mean aspect ratio A < 4, is driven both by the desire to find attractive fusion reactors at an economical size and to merge the favorable features of tokamaks (good confinement, high beta) and stellarators (low recirculating power), thus achieving a hybrid device with finite bootstrap current, external kink stability (at moderate beta) in the absence of a conducting wall, and immunity to disruptions. The large transport ripple-driven losses of conventional stellarators are overcome in two basically different ways. Quasi-axisymmetric stellarators (QAS) achieve tokamak-like neoclassical transport levels by tailoring the magnetic field spectrum to be approximately axisymmetric in Boozer coordinates. These devices have bootstrap current profiles and magnitudes comparable to that in a tokamak. Unlike a tokamak, a QAS can have rotational transform profiles, modified by external coils, which have positive edge shear and hence good kink and neoclassical-tearing stability (island suppression). In contrast, quasi-omnigenous stellarators (QOS) rely on the confinement of J*-contours to achieve low transport levels. QOS can have transform profiles, and hence stability properties, similar to QAS, but with smaller values of self-consistent bootstrap currents. Powerful physics and coil optimization codes are being developed to design experiments to test these two compact stellarator approaches: a PoP-sized QAS to be built at PPPL and a concept-exploration experiment based on a QOS.
NSDL National Science Digital Library
Founded in 1985 by the presidents of Brown, Georgetown and Stanford universities, the Campus Compact organization was designed to combat the popular image of college students as being wholly self-absorbed and uninterested in the broad range of social concerns outside the walls of their respective colleges and universities. Today, the organization remains committed to helping a wide variety of institutions create supportive academic environments for community service and to forming partnerships with a host of institutions, including those in the worlds of business and social-service providers. As might be expected, there is a wide range of free publications available on the site, including materials on starting campus-community partnerships, information on relevant legislation and policy, and materials on incorporating service-learning projects into the college-level curriculum. Of course, visitors will want to take a look at the current edition (and the archived issues) of their two fine in-house publications, the Campus Compact Reader (which highlights the best writing on civic education and service-learning from around the US), and the Compact Current, which is the organization's quarterly newsletter for organizations and institutions involved in public and community service.
Compaction localization and fluid flow
NASA Astrophysics Data System (ADS)
Holcomb, D. J.; Olsson, W. A.
2003-06-01
When subjected to nonhydrostatic, compressive stresses, some porous sandstones exhibit nonuniform compaction. The compaction occurs as a localization process, analogous to shear localization, but results in a thickening, tabular zone of compaction as opposed to culminating in a shear fracture. We report the results of several triaxial compression experiments done at a confining pressure of 45 MPa on Castlegate sandstone, measuring simultaneously, stress, strain, acoustic emission locations, and permeability. A major result is that compaction localization produces up to a 2 order-of-magnitude decrease in permeability. Correlation of local strain measurements and acoustic emission locations made on the same specimen show that the compaction process proceeds as a propagating front approximately 20 mm thick. A model of the compaction process was developed that incorporates the moving boundary between compacted, low-permeability regions and uncompacted, higher-permeability regions, and compaction-induced fluid injection at the boundaries. Because of the inhomogeneous nature of compaction produced by compaction localization, and its temporal evolution, a number of phenomena related to fluid flow are predicted by the model: locally increased pore pressures and spatial changes in the effective permeability. Experimental results are reported that show the evolution of effective permeability to be linear with respect to the distance the compaction fronts propagated as predicted by the model. Implications of the results for future experimentation and for reservoirs are briefly discussed; in particular, the interaction between compaction-induced fluid pressure and compaction localization should lead to a phenomenon analogous to dilatancy hardening, impeding the propagation of compaction bands.
Design of a compact structure cancer therapy synchrotron
NASA Astrophysics Data System (ADS)
Yang, J. C.; Shi, J.; Chai, W. P.; Xia, J. W.; Yuan, Y. J.; Li, Y.
2014-08-01
HIMM, a new compact accelerator facility dedicated to carbon cancer therapy, has been designed and is presently under construction. The synchrotron has a compact structure that exhibits a circumference of only 56.2 m. The charge exchange injection (CEI) method is adopted for synchrotron injection with a carbon-ion energy of 7 MeV/u. The third-order resonance and RF-Knock Out scheme are adopted in this machine. The general design of the machine and injection/extraction simulation results is discussed in this paper.
Equilibria of EV Charging Benny Lutati1
Yeoh, William
of grid-integrated vehicles, which can also discharge energy back to the grid, is a natural application model of the problem of charging and discharging electrical vehicles. Interaction among agents takes-response process. A compact representation of FCGs and a distributed algorithm that enables efficient best
Development of a repetitive compact torus injector
NASA Astrophysics Data System (ADS)
Onchi, Takumi; McColl, David; Dreval, Mykola; Rohollahi, Akbar; Xiao, Chijin; Hirose, Akira; Zushi, Hideki
2013-10-01
A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. This work has been sponsored by the CRC and NSERC, Canada.
J. Albrecht; M. Artuso; K. Babu; R. H. Bernstein; T. Blum; D. N. Brown; B. C. K. Casey; C. -h. Cheng; V. Cirigliano; A. Cohen; A. Deshpande; E. C. Dukes; B. Echenard; A. Gaponenko; D. Glenzinski; M. Gonzalez-Alonso; F. Grancagnolo; Y. Grossman; R. C. Group; R. Harnik; D. G. Hitlin; B. Kiburg; K. Knoepfe; K. Kumar; G. Lim; Z. -T. Lu; D. McKeen; J. P. Miller; M. Ramsey-Musolf; R. Ray; B. L. Roberts; M. Rominsky; Y. Semertzidis; D. Stoeckinger; R. Talman; R. Van De Water; P. Winter
2013-11-24
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.
Kim D Blake; Chitra Prasad
2006-01-01
CHARGE syndrome was initially defined as a non-random association of anomalies (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, Ear anomalies\\/deafness). In 1998, an expert group defined the major (the classical 4C's: Choanal atresia, Coloboma, Characteristic ears and Cranial nerve anomalies) and minor criteria of CHARGE syndrome. Individuals with all four major characteristics or three major and
NASA Astrophysics Data System (ADS)
LoSecco, John
2015-08-01
Some evidence for sterile neutrinos has been found in short baseline observations where the measured neutrino flux did not agree with expectations. Systematic uncertainties from the expected values have limited the sensitivity of this approach. Observation at multiple distances can remove the normalization uncertainty by isolating the distance dependence. This does not work for high-? m2 sterile neutrinos since they are fully mixed at most observation distances and only shift the normalization of the flux. A compact intense source of neutrinos based on a subcritical fission reactor would permit observation of oscillations on submeter distance scales and clearly distinguish between a systematic normalization and the L /E dependence expected from oscillations.
Kurennoy, S S; O' Hara, J F; Rybarcyk, L J
2008-01-01
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.
NASA Technical Reports Server (NTRS)
Foster, John E.
2004-01-01
A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.
Debades Bandyopadhyay
2005-12-28
We discuss $\\beta$-equilibrated and charge neutral matter involving hyperons and $\\bar K$ condensates within relativistic models. It is observed that populations of baryons are strongly affected by the presence of antikaon condensates. Also, the equation of state including $\\bar K$ condensates becomes softer resulting in a smaller maximum mass neutron star.
Compaction of Titanium Powders
Stephen J. Gerdemann; Paul D. Jablonski
2010-11-01
Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 ?m, <75 ?m, and < 45 ?m; two different sizes of a hydride-dehydride [HDH] <75 ?m and < 45 ?m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.
Compaction of Titanium Powders
NASA Astrophysics Data System (ADS)
Gerdemann, Stephen J.; Jablonski, Paul D.
2011-05-01
Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 ?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.
Compact electrostatic comb actuator
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
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).
Charge without charge in quarks
Harry Schiff
2013-08-06
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.
Engineering Prototype for a Compact Medical Dielectric Wall Accelerator
Zografos, Anthony; Hening, Andy; Joshkin, Vladimir; Leung, Kevin; Pearson, Dave; Pearce-Percy, Henry; Rougieri, Mario; Parker, Yoko; Weir, John; Blackfield, Donald; Chen, Yu-Jiuan; Falabella, Steven; Guethlein, Gary; Poole, Brian; Hamm, Robert W.; Becker, Reinard
2011-12-13
A compact accelerator system architecture based on the dielectric wall accelerator (DWA) for medical proton beam therapy has been developed by the Compact Particle Acceleration Corporation (CPAC). The major subsystems are a Radio Frequency Quadrupole (RFQ) injector linac, a pulsed kicker to select the desired proton bunches, and a DWA linear accelerator incorporating a high gradient insulator (HGI) with stacked Blumleins to produce the required acceleration energy. The Blumleins are switched with solid state laser-driven optical switches integrated into the Blumlein assemblies. Other subsystems include a high power pulsed laser, fiber optic distribution system, electrical charging system, and beam diagnostics. An engineering prototype has been constructed and characterized, and these results will be used within the next three years to develop an extremely compact 150 MeV system capable of modulating energy, beam current, and spot size on a shot-to-shot basis. This paper presents the details the engineering prototype, experimental results, and commercialization plans.
Atacama compact array antennas
NASA Astrophysics Data System (ADS)
Saito, M.; Inatani, J.; Nakanishi, K.; Saito, H.; Iguchi, S.
2012-09-01
The ACA (Atacama Compact Array) system is an important element of ALMA and consists of four ACA 12-m antennas and twelve ACA 7-m antennas. The ACA system aims to acquire the total power data with four 12-m antennas and the short baseline interferometer data with 7-m antennas. The ACA system also increases reliability of the interferometer maps of astronomical sources larger than the field view of the 12-m antenna. The science performance of these antennas has been extensively verified at OSF (operation support facility) at an elevation of 2900 m in Atacama desert in northern Chile since 2007. The pointing performance has been verified with a dedicated optical pointing telescope, the servo performance is tested with angle encoders, and the surface accuracy has been measured with a radio holography method. Both ACA 12-m antennas and 7-m antennas have been successfully demonstrated to meet the very stringent ALMA specifications.
Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)
1993-01-01
An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.
Benson, D.K.; Potter, T.F.
1993-01-05
An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.
Compact vacuum insulation embodiments
Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)
1992-01-01
An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.
Multipurpose Compact Spectrometric Unit
Bocarov, Viktor; Cermak, Pavel; Mamedov, Fadahat; Stekl, Ivan
2009-11-09
A new standalone compact spectrometer was developed. The device consists of analog (peamplifier, amplifier) and digital parts. The digital part is based on the 160 MIPS Digital Signal Processor. It contains 20 Msps Flash-ADC, 1 MB RAM for spectra storage, 128 KB Flash/ROM for firmware storage, Real Time Clock and several voltage regulators providing the power for user peripherals (e.g. amplifier, temperature sensors, etc.). Spectrometer is connected with a notebook via high-speed USB 2.0 bus. The spectrometer is multipurpose device, which is planned to be used for measurements of Rn activities, energy of detected particles by CdTe pixel detector or for coincidence measurements.
Bennett, Gloria A. (Los Alamos, NM)
1992-01-01
A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.
NASA Technical Reports Server (NTRS)
Wiker, G. A.; Mann, W. A. (inventors)
1979-01-01
A relatively simple, compact artificial hand, is described which includes hooks pivotally mounted on first frame to move together and apart. The first frame is rotatably mounted on a second frame to enable "turning at the wrist" movement without limitation. The second frame is pivotally mounted on a third frame to permit 'flexing at the wrist' movement. A hook-driving motor is fixed to the second frame but has a shaft that drives a speed reducer on the first frame which, in turn, drives the hooks. A second motor mounted on the second frame, turns a gear on the first frame to rotate the first frame and the hooks thereon. A third motor mounted on the third frame, turns a gear on a second frame to pivot it.
Bennett, G.A.
1992-11-24
A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.
Endogenous phosphorylation of basic protein in myelin of varying degrees of compaction
Schulz, P.; Moscarello, M.A. (Hospital for Sick Children, Toronto, Ontario (Canada)); Cruz, T.F. (Univ. of Coimbra (Portugal))
1988-10-04
Fractions containing myelin of varying degrees of compaction were prepared from human white matter. Protein kinase activity in these fractions was measured by using both endogenous and exogenous myelin basic protein (MBP) as substrates. In both cases, less compact myelin fractions possessed higher levels of protein kinase activity than the compact myelin fraction. In addition, the specific activity of phosphorylated basic protein was greater in the loosely compacted fractions than in compact multilamellar myelin. When basic protein in compact myelin or the myelin fractions was phosphorylated by the endogenous kinase, approximately 70% of the ({sup 32}P)phosphate was incorporated at a single site, identified as Ser-102. The remaining 30% was found in three other minor sites. Electron microscopy of less compact myelin showed it was composed of fewer lamellae which correlated with a relative decrease in the proportion of cationic charge isomers (microheteromers) when MBP was subjected to gel electrophoresis at alkaline pH. The shift in charge microheterogeneity of basic protein to the less cationic isomers in the less compact myelin fractions correlated with an increase in protein kinase activity and a greater specific activity of phosphorylated basic protein.
The Finslerian compact star model
Farook Rahaman; Nupur Paul; S. S. De; Saibal Ray; Md. Abdul Kayum Jafry
2015-06-02
We construct a toy model for compact stars based on the Finslerian structure of spacetime. By assuming a particular mass function, we find an exact solution of the Finsler-Einstein field equations with an anisotropic matter distribution. The solutions are revealed to be physically interesting and pertinent for the explanation of compact stars.
75 FR 17161 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact
Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-05
...the Compact Council for the National Crime Prevention and Privacy Compact AGENCY...to announce a meeting of the National Crime Prevention and Privacy Compact Council (Council) created by the National Crime Prevention and Privacy Compact Act...
Compaction of DNA with Lipid Modified Silica Nanoparticles
NASA Astrophysics Data System (ADS)
Savarala, Sushma; Wunder, Stephanie L.; Ilies, Marc
2012-02-01
There is an increasing interest in modified inorganic nanoparticles, polymers or hybrid polymer-inorganic nanoparticles for use in DNA transfection, rather than viral vectors or liposomes. Adsorption of the DNA to the nanoparticles prevents enzymatic degradation of the DNA, although the reason for this protection is not completely understood. In order to compact the negatively charged DNA, a positively charged surface is required, and for transfection applications, the nanosystems must remain stable in suspension. It is also useful to minimize the amount of cytotoxic cationic lipid needed for DNA compaction in delivery applications. Here we investigate the colloidal stability of supported lipid bilayers (SLBs) composed of mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC, 14:0 PC) and 1,2-dimyristoyl-3-trimethylammonium-propane (DMTAP, 14:0 TAP), and their ability to compact plasmid DNA. Ionic strengths and DMPC/DMTAP ratios that resulted in SLB formation, no excess small unilamellar vesicles (SUVs) in the suspensions, and colloidal stability, were determined. DNA/SLB/lipid ratios that resulted in compaction were then investigated.
Compact Linear Collider drive beam phase stabilization simulations
NASA Astrophysics Data System (ADS)
Gerbershagen, A.; Schulte, D.; Burrows, P. N.
2015-04-01
The drive beam phase stability is one of the critical feasibility issues of the Compact Linear Collider (CLIC) project. This paper presents a step-by-step analysis of the error propagation through the CLIC drive beam complex using realistic rf potential and beam loading amplitude functions for the drive and main beam accelerating structures. The impact of planned stabilization systems for drive beam bunch charge and longitudinal phase is simulated and the optimal specifications for such systems are calculated and discussed.
Fractional statistics in three dimensions: Compact Maxwell-Higgs system
Fort, H.; Gambini, R. [Instituto de Fisica, Facultad de Ciencias, Tristan Narvaja 1674, 11200 Montevideo (Uruguay)] [Instituto de Fisica, Facultad de Ciencias, Tristan Narvaja 1674, 11200 Montevideo (Uruguay)
1996-07-01
We show that a (3+1)-dimensional system composed of an open magnetic vortex and an electrical point charge exhibits the phenomenon of Fermi-Bose transmutation. In order to provide the physical realization of this system we focus on the lattice compact scalar electrodynamics SQED{sub {ital c}} whose topological excitations are open Nielsen-Olesen strings with magnetic monopoles attached at their ends. {copyright} {ital 1996 The American Physical Society.}
NSDL National Science Digital Library
Eric Muller
1995-01-01
In this trick, learners discover how to stick a straw to the palm of their hand, window door, or anywhere using static electricity. This activity introduces learners to negative and positive charges and shows how opposites attract. Note: this trick works best in low humidity (dry air).
A Compact Ring Design with Tunable Momentum Compaction
Sun, Y.; /SLAC; ,
2012-05-17
A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.
FIRST COUNTABLE, COUNTABLY COMPACT, NONCOMPACT PETER NYIKOS
Nyikos, Peter J.
subset has compact clo- sure, and strongly -bounded if every -compact subset has compact closure. Also, this doesn't work with "locally countable" in place of "first countable," as shown by an example of mine
7 CFR 51.582 - Fairly compact.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 2010-01-01 2010-01-01 false Fairly compact. 51.582 Section 51.582 Agriculture ...Standards for Celery Definitions § 51.582 Fairly compact. Fairly compact means that the branches on the stalk are...
A compact electron spectrometer for an LWFA.
Lumpkin, A.; Crowell, R.; Li, Y.; Nemeth, K.
2007-01-01
The use of a laser wakefield accelerator (LWFA) beam as a driver for a compact free-electron laser (FEL) has been proposed recently. A project is underway at Argonne National Laboratory (ANL) to operate an LWFA in the bubble regime and to use the quasi-monoenergetic electron beam as a driver for a 3-m-long undulator for generation of sub-ps UV radiation. The Terawatt Ultrafast High Field Facility (TUHFF) in the Chemistry Division provides the 20-TW peak power laser. A compact electron spectrometer whose initial fields of 0.45 T provide energy coverage of 30-200 MeV has been selected to characterize the electron beams. The system is based on the Ecole Polytechnique design used for their LWFA and incorporates the 5-cm-long permanent magnet dipole, the LANEX scintillator screen located at the dispersive plane, a Roper Scientific 16-bit MCP-intensified CCD camera, and a Bergoz ICT for complementary charge measurements. Test results on the magnets, the 16-bit camera, and the ICT will be described, and initial electron beam data will be presented as available. Other challenges will also be addressed.
Benson, D.K.; Potter, T.F.
1992-10-27
Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.
Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)
1992-01-01
Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases therebetween are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and variious laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels.
Compact Dexterous Robotic Hand
NASA Technical Reports Server (NTRS)
Lovchik, Christopher Scott (Inventor); Diftler, Myron A. (Inventor)
2001-01-01
A compact robotic hand includes a palm housing, a wrist section, and a forearm section. The palm housing supports a plurality of fingers and one or more movable palm members that cooperate with the fingers to grasp and/or release an object. Each flexible finger comprises a plurality of hingedly connected segments, including a proximal segment pivotally connected to the palm housing. The proximal finger segment includes at least one groove defining first and second cam surfaces for engagement with a cable. A plurality of lead screw assemblies each carried by the palm housing are supplied with power from a flexible shaft rotated by an actuator and output linear motion to a cable move a finger. The cable is secured within a respective groove and enables each finger to move between an opened and closed position. A decoupling assembly pivotally connected to a proximal finger segment enables a cable connected thereto to control movement of an intermediate and distal finger segment independent of movement of the proximal finger segment. The dexterous robotic hand closely resembles the function of a human hand yet is light weight and capable of grasping both heavy and light objects with a high degree of precision.
Leung, Ka-Ngo; Lou, Tak Pui
2005-03-22
A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.
Compact fission counter for DANCE
Wu, C Y; Chyzh, A; Kwan, E; Henderson, R; Gostic, J; Carter, D; Bredeweg, T; Couture, A; Jandel, M; Ullmann, J
2010-11-06
The Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 BF{sub 2} crystals with equal solid-angle coverage. DANCE is a 4{pi} {gamma}-ray calorimeter and designed to study the neutron-capture reactions on small quantities of radioactive and rare stable nuclei. These reactions are important for the radiochemistry applications and modeling the element production in stars. The recognition of capture event is made by the summed {gamma}-ray energy which is equivalent of the reaction Q-value and unique for a given capture reaction. For a selective group of actinides, where the neutron-induced fission reaction competes favorably with the neutron capture reaction, additional signature is needed to distinguish between fission and capture {gamma} rays for the DANCE measurement. This can be accomplished by introducing a detector system to tag fission fragments and thus establish a unique signature for the fission event. Once this system is implemented, one has the opportunity to study not only the capture but also fission reactions. A parallel-plate avalanche counter (PPAC) has many advantages for the detection of heavy charged particles such as fission fragments. These include fast timing, resistance to radiation damage, and tolerance of high counting rate. A PPAC also can be tuned to be insensitive to {alpha} particles, which is important for experiments with {alpha}-emitting actinides. Therefore, a PPAC is an ideal detector for experiments requiring a fast and clean trigger for fission. A PPAC with an ingenious design was fabricated in 2006 by integrating amplifiers into the target assembly. However, this counter was proved to be unsuitable for this application because of issues related to the stability of amplifiers and the ability to separate fission fragments from {alpha}'s. Therefore, a new design is needed. A LLNL proposal to develop a new PPAC for DANCE was funded by NA22 in FY09. The design goal is to minimize the mass for the proposed counter and still be able to maintain a stable operation under extreme radioactivity and the ability to separate fission fragments from {alpha}'s. In the following sections, the description is given for the design and performance of this new compact PPAC, for studying the neutron-induced reactions on actinides using DANCE at LANL.
CHARGING AND COAGULATION OF DUST IN PROTOPLANETARY PLASMA ENVIRONMENTS
Matthews, L. S.; Land, V.; Hyde, T. W., E-mail: lorin_matthews@baylor.edu [Center for Astrophysics, Space Physics, and Engineering Research, Baylor University, Waco, TX 76798-7316 (United States)
2012-01-01
Combining a particle-particle, particle-cluster, and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in plasma environments relevant for protoplanetary disks have been investigated, including the effect of electron depletion in high dust density environments. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, and that cluster-cluster aggregation is significantly more effective than particle-cluster aggregation. Comparisons of the grain structure show that with increasing aggregate charge the compactness factor, {phi}{sub {sigma}}, decreases and has a narrower distribution, indicating a fluffier structure. Neutral aggregates are more compact, with larger {phi}{sub {sigma}}, and exhibit a larger variation in fluffiness. Overall, increased aggregate charge leads to larger, fluffier, and more massive aggregates.
Net charge fluctuations and local charge compensation
Fu Jinghua
2006-12-15
We propose net charge fluctuation as a measure of local charge correlation length. It is demonstrated that, in terms of a schematic multiperipheral model, net charge fluctuation satisfies the same Quigg-Thomas relation as satisfied by charge transfer fluctuation. Net charge fluctuations measured in finite rapidity windows depend on both the local charge correlation length and the size of the observation window. When the observation window is larger than the local charge correlation length, the net charge fluctuation only depends on the local charge correlation length, while forward-backward charge fluctuations always have strong dependence on the observation window size. Net charge fluctuations and forward-backward charge fluctuations measured in the present heavy ion experiments show characteristic features similar to those from multiperipheral models. But the data cannot all be understood within this simple model.
New considerations for compact cyclotrons
Marshall, Eric S. (Eric Scott)
2012-01-01
A compact cyclotron built with superconducting magnets could be a transformative solution to many scientific problems facing the defense, medical, and energy industries today. This thesis discusses three potential applications ...
Compact, Reliable EEPROM Controller
NASA Technical Reports Server (NTRS)
Katz, Richard; Kleyner, Igor
2010-01-01
A compact, reliable controller for an electrically erasable, programmable read-only memory (EEPROM) has been developed specifically for a space-flight application. The design may be adaptable to other applications in which there are requirements for reliability in general and, in particular, for prevention of inadvertent writing of data in EEPROM cells. Inadvertent writes pose risks of loss of reliability in the original space-flight application and could pose such risks in other applications. Prior EEPROM controllers are large and complex and do not provide all reasonable protections (in many cases, few or no protections) against inadvertent writes. In contrast, the present controller provides several layers of protection against inadvertent writes. The controller also incorporates a write-time monitor, enabling determination of trends in the performance of an EEPROM through all phases of testing. The controller has been designed as an integral subsystem of a system that includes not only the controller and the controlled EEPROM aboard a spacecraft but also computers in a ground control station, relatively simple onboard support circuitry, and an onboard communication subsystem that utilizes the MIL-STD-1553B protocol. (MIL-STD-1553B is a military standard that encompasses a method of communication and electrical-interface requirements for digital electronic subsystems connected to a data bus. MIL-STD- 1553B is commonly used in defense and space applications.) The intent was to both maximize reliability while minimizing the size and complexity of onboard circuitry. In operation, control of the EEPROM is effected via the ground computers, the MIL-STD-1553B communication subsystem, and the onboard support circuitry, all of which, in combination, provide the multiple layers of protection against inadvertent writes. There is no controller software, unlike in many prior EEPROM controllers; software can be a major contributor to unreliability, particularly in fault situations such as the loss of power or brownouts. Protection is also provided by a powermonitoring circuit.
NSDL National Science Digital Library
Integrated Teaching and Learning Program,
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.
NSDL National Science Digital Library
Jack D. Thatcher (Lewisburg; West Virginia School of Osteopathic Medicine REV)
2013-04-16
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.
G IDEALS OF COMPACT SETS SLAWOMIR SOLECKI
Solecki, Slawomir
G IDEALS OF COMPACT SETS SLAWOMIR SOLECKI Abstract. We investigate the structure of G ideals of compact sets. We define a class of G ideals of compact sets that, on the one hand, avoids certain phenomena present among general G ideals of compact sets and, on the other hand, includes all naturally
The interstate river compact: Incentives for noncompliance
Lynne Lewis Bennett; Charles W. Howe
1998-01-01
Twenty-one western United States rivers are governed by interstate compacts. This paper examines the issue of compliance with interstate river compacts in the western United States and some of the factors influencing compact compliance. Theoretical arguments and empirical evidence presented in this paper suggest that upper basin states governed by interstate compacts with percentage delivery rules are more likely to
Compact Optoelectronic Compass
NASA Technical Reports Server (NTRS)
Christian, Carl
2004-01-01
A compact optoelectronic sensor unit measures the apparent motion of the Sun across the sky. The data acquired by this chip are processed in an external processor to estimate the relative orientation of the axis of rotation of the Earth. Hence, the combination of this chip and the external processor finds the direction of true North relative to the chip: in other words, the combination acts as a solar compass. If the compass is further combined with a clock, then the combination can be used to establish a threeaxis inertial coordinate system. If, in addition, an auxiliary sensor measures the local vertical direction, then the resulting system can determine the geographic position. This chip and the software used in the processor are based mostly on the same design and operation as those of the unit described in Micro Sun Sensor for Spacecraft (NPO-30867) elsewhere in this issue of NASA Tech Briefs. Like the unit described in that article, this unit includes a small multiple-pinhole camera comprising a micromachined mask containing a rectangular array of microscopic pinholes mounted a short distance in front of an image detector of the active-pixel sensor (APS) type (see figure). Further as in the other unit, the digitized output of the APS in this chip is processed to compute the centroids of the pinhole Sun images on the APS. Then the direction to the Sun, relative to the compass chip, is computed from the positions of the centroids (just like a sundial). In the operation of this chip, one is interested not only in the instantaneous direction to the Sun but also in the apparent path traced out by the direction to the Sun as a result of rotation of the Earth during an observation interval (during which the Sun sensor must remain stationary with respect to the Earth). The apparent path of the Sun across the sky is projected on a sphere. The axis of rotation of the Earth lies at the center of the projected circle on the sphere surface. Hence, true North (not magnetic North), relative to the chip, can be estimated from paths of the Sun images across the APS. In a test, this solar compass has been found to yield a coarse estimate of the North (within tens of degrees) in an observation time of about ten minutes. As expected, the accuracy was found to increase with observation time: after a few hours, the estimated direction of the rotation axis becomes accurate to within a small fraction of a degree.
Non-Compact Cardiomyopathy or Ventricular Non-Compact Syndrome?
2014-01-01
Ventricular myocardial non-compaction has been recognized and defined as a genetic cardiomyopathy by American Heart Association since 2006. The argument on the nomenclature and pathogenesis of this kind of ventricular myocardial non-compaction characterized by regional ventricular wall thickening and deep trabecular recesses often complicated with chronic heart failure, arrhythmia and thromboembolism and usually overlap the genetics and phenotypes of other kind of genetic or mixed cardiomyopathy still exist. The proper classification and correct nomenclature of the non-compact ventricles will contribute to the precisely and completely understanding of etiology and its related patho-physiological mechanism for a better risk stratification and more personalized therapy of the disease individually. All of the genetic heterogeneity and phenotypical overlap and the variety in histopathological, electromechanical and clinical presentation indicates that some of the cardiomyopathies might just be the different consequence of myocardial development variations related to gene mutation and phenotype of one or group genes induced by the interacted and disturbed process of gene modulation at different links of gene function expression and some other etiologies. This review aims to establish a new concept of "ventricular non-compaction syndrome" based on the demonstration of the current findings of etiology, epidemiology, histopathology and echocardiography related to the disorder of ventricular myocardial compaction and myocardial electromechanical function development. PMID:25580189
NASA Astrophysics Data System (ADS)
Rindler, Filip
2015-01-01
This work introduces microlocal compactness forms (MCFs) as a new tool to study oscillations and concentrations in L p -bounded sequences of functions. Decisively, MCFs retain information about the location, value distribution, and direction of oscillations and concentrations, thus extending at the same time the theories of (generalized) Young measures and H-measures. In L p -spaces oscillations and concentrations precisely discriminate between weak and strong compactness, and thus MCFs allow one to quantify the difference in compactness. The definition of MCFs involves a Fourier variable, whereby differential constraints on the functions in the sequence can also be investigated easily—a distinct advantage over Young measure theory. Furthermore, pointwise restrictions are reflected in the MCF as well, paving the way for applications to Tartar's framework of compensated compactness; consequently, we establish a new weak-to-strong compactness theorem in a "geometric" way. After developing several aspects of the abstract theory, we consider three applications; for lamination microstructures, the hierarchy of oscillations is reflected in the MCF. The directional information retained in an MCF is harnessed in the relaxation theory for anisotropic integral functionals. Finally, we indicate how the theory pertains to the study of propagation of singularities in certain systems of PDEs. The proofs combine measure theory, Young measures, and harmonic analysis.
Compact boson stars in K field theories
NASA Astrophysics Data System (ADS)
Adam, C.; Grandi, N.; Klimas, P.; Sánchez-Guillén, J.; Wereszczy?ski, A.
2010-11-01
We study a scalar field theory with a non-standard kinetic term minimally coupled to gravity. We establish the existence of compact boson stars, that is, static solutions with compact support of the full system with self-gravitation taken into account. Concretely, there exist two types of solutions, namely compact balls on the one hand, and compact shells on the other hand. The compact balls have a naked singularity at the center. The inner boundary of the compact shells is singular, as well, but it is, at the same time, a Killing horizon. These singular, compact shells therefore resemble black holes.
NASA Technical Reports Server (NTRS)
Thompson, Karl E.; Rust, David M.; Chen, Hua
1995-01-01
A new type of image detector has been designed to analyze the polarization of light simultaneously at all picture elements (pixels) in a scene. The Integrated Dual Imaging Detector (IDID) consists of a polarizing beamsplitter bonded to a custom-designed charge-coupled device with signal-analysis circuitry, all integrated on a silicon chip. The IDID should simplify the design and operation of imaging polarimeters and spectroscopic imagers used, for example, in atmospheric and solar research. Other applications include environmental monitoring and robot vision. Innovations in the IDID include two interleaved 512 x 1024 pixel imaging arrays (one for each polarization plane), large dynamic range (well depth of 10(exp 6) electrons per pixel), simultaneous readout and display of both images at 10(exp 6) pixels per second, and on-chip analog signal processing to produce polarization maps in real time. When used with a lithium niobate Fabry-Perot etalon or other color filter that can encode spectral information as polarization, the IDID can reveal tiny differences between simultaneous images at two wavelengths.
NHS charges. Light on the charge brigade.
Eversley, J; Webster, C
1997-07-17
Patients charges form a very small part of NHS income. Governments have often used charges to emphasise their commitment to austerity. Knowledge of the effect of charges on public health, equity and eliminating waste is limited. Both Conservative and Labour health ministers have made attempts to abolish charges. PMID:10169049
Charged particle distributions in Jupiter's magnetosphere
Neil Divine; H. B. Garrett
1983-01-01
In situ data from the Pioneer and Voyager spacecraft, supplemented by earth-based observations and theoretical considerations, are used as the basis for the present quantitative, compact model of the 1 eV-several MeV charged particle distribution in the Jovian magnetosphere. The thermal plasma parameters of convection speed, number density, and characteristic energy, are specified as functions of position for electrons and
Modelling of compaction in planetesimals
NASA Astrophysics Data System (ADS)
Neumann, Wladimir; Breuer, Doris; Spohn, Tilman
2014-07-01
Aims: Compaction of initially porous material prior to melting is an important process that has influenced the interior structure and the thermal evolution of planetesimals in their early history. On the one hand, compaction decreases the porosity resulting in a reduction of the radius and on the other hand, the loss of porosity results in an increase of the thermal conductivity of the material and thus in a more efficient cooling. Porosity loss by hot pressing is the most efficient process of compaction in planetesimals and can be described by creep flow, which depends on temperature and stress. Hot pressing has been repeatedly modelled using a simplified approach, for which the porosity is gradually reduced in some fixed temperature interval between ?650 K and 700 K. This approach neglects the dependence of compaction on stress and other factors such as matrix grain size and creep activation energy. In the present study, we compare this parametrised method with a self-consistent calculation of porosity loss via a creep related approach. Methods: We use our thermal evolution model from previous studies to model compaction of an initially porous body and consider four basic packings of spherical dust grains (simple cubic, orthorhombic, rhombohedral, and body-centred cubic). Depending on the grain packing, we calculate the effective stress and the associated porosity change via the thermally activated creep flow. For comparison, compaction is also modelled by simply reducing the initial porosity linearly to zero between 650 K and 700 K. As we are interested in thermal metamorphism and not melting, we only consider bodies that experience a maximum temperature below the solidus temperature of the metal phase. Results: For the creep related approach, the temperature interval in which compaction takes place depends strongly on the size of the planetesimal and is not fixed as assumed in the parametrised approach. Depending on the radius, the initial grain size, the activation energy, and the initial porosity and specific packing of the dust grains, the temperature interval lies within 500-1000 K. This finding implies that the parametrised approach strongly overestimates compaction and underestimates the maximum temperature. For the cases considered, the post-compaction porous layer retained at the surface is a factor of 1.5 to 4 thicker for the creep related approach. The difference in the temperature evolution between the two approaches increases with decreasing radius and the maximum temperature can deviate by over 30% for small bodies. Appendix is available in electronic form at http://www.aanda.org
Chakraborty, Semanti; Chakraborty, Jayanta
2012-12-01
We present here a case of 17-year-old boy from Kolkata presenting with obesity, bilateral gynecomastia, mental retardation, and hypogonadotrophic hypogonadism. The patient weighed 70 kg and was of 153 cm height. Facial asymmetry (unilateral facial palsy), gynecomastia, decreased pubic and axillary hair, small penis, decreased right testicular volume, non-palpable left testis, and right-sided congenital inguinal hernia was present. The patient also had disc coloboma, convergent squint, microcornea, microphthalmia, pseudohypertelorism, low set ears, short neck, and choanalatresia. He had h/o VSD repaired with patch. Laboratory examination revealed haemoglobin 9.9 mg/dl, urea 24 mg/dl, creatinine 0.68 mg/dl. IGF1 77.80 ng/ml (decreased for age), GH <0.05 ng/ml, testosterone 0.25 ng/ml, FSH-0.95 ?IU/ml, LH 0.60 ?IU/ml. ACTH, 8:00 A.M cortisol, FT3, FT4, TSH, estradiol, DHEA-S, lipid profile, and LFT was within normal limits. Prolactin was elevated at 38.50 ng/ml. The patient's karyotype was 46XY. Echocardiography revealed ventricularseptal defect closed with patch, grade 1 aortic regurgitation, and ejection fraction 67%. Ultrasound testis showed small right testis within scrotal sac and undescended left testis within left inguinal canal. CT scan paranasal sinuses revealed choanalatresia and deviation of nasal septum to the right. Sonomammography revealed bilateral proliferation of fibroglandular elements predominantly in subareoalar region of breasts. MRI of brain and pituitary region revealed markedly atrophic pituitary gland parenchyma with preserved infundibulum and hypothalamus and widened suprasellar cistern. The CHARGE association is an increasingly recognized non-random pattern of congenital anomalies comprising of coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or deafness.[1] These anomalies have a higher probability of occurring together. In this report, we have described a boy with CHARGE association. PMID:23565479
ULTRA-COMPACT ACCELERATOR TECHNOLOGIES FOR APPLICATION IN NUCLEAR TECHNIQUES
Sampayan, S; Caporaso, G; Chen, Y; Carazo, V; Falabella, S; Guethlein, G; Guse, S; Harris, J R; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Paul, A C; Pearson, D; Poole, B; Schmidt, R; Sanders, D; Selenes, K; Sitaraman, S; Sullivan, J; Wang, L; Watson, J
2009-06-11
We report on compact accelerator technology development for potential use as a pulsed neutron source quantitative post verifier. The technology is derived from our on-going compact accelerator technology development program for radiography under the US Department of Energy and for a clinic sized compact proton therapy systems under an industry sponsored Cooperative Research and Development Agreement. The accelerator technique relies on the synchronous discharge of a prompt pulse generating stacked transmission line structure with the beam transit. The goal of this technology is to achieve {approx}10 MV/m gradients for 10s of nanoseconds pulses and to {approx}100 MV/m gradients for {approx}1 ns systems. As a post verifier for supplementing existing x-ray equipment, this system can remain in a charged, stand-by state with little or no energy consumption. We detail the progress of our overall component development effort with the multilayer dielectric wall insulators (i.e., the accelerator wall), compact power supply technology, kHz repetition-rate surface flashover ion sources, and the prompt pulse generation system consisting of wide-bandgap switches and high performance dielectric materials.
ULTRA-COMPACT ACCELERATOR TECHNOLOGIES FOR APPLICATION IN NUCLEAR TECHNIQUES
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.; Carazo, V.; Guse, S.; Pearson, D.; Schmidt, R.
2009-12-02
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.
Weakly Charged Cationic Nanoparticles Induce DNA Bending and Strand Separation
Railsback, Justin [North Carolina State University; Singh, Abhishek [North Carolina State University; Pearce, Ryan [North Carolina State University; McKnight, Timothy E [ORNL; Collazo, Ramon [North Carolina State University; Sitar, Zlatko [ORNL; Yingling, Yaroslava [North Carolina State University; Melechko, Anatoli Vasilievich [ORNL
2012-01-01
The understanding of interactions between double stranded (ds) DNA and charged nanoparticles will have a broad bearing on many important applications from drug delivery [ 1 4 ] to DNAtemplated metallization. [ 5 , 6 ] Cationic nanoparticles (NPs) can bind to DNA, a negatively charged molecule, through a combination of electrostatic attraction, groove binding, and intercalation. Such binding events induce changes in the conformation of a DNA strand. In nature, DNA wraps around a cylindrical protein assembly (diameter and height of 6 nm) [ 7 ] with an 220 positive charge, [ 8 ] creating the complex known as chromatin. Wrapping and bending of DNA has also been achieved in the laboratory through the binding of highly charged species such as molecular assemblies, [ 9 , 10 ] cationic dendrimers, [ 11 , 12 ] and nanoparticles. [ 13 15 ] The charge of a nanoparticle plays a crucial role in its ability to induce DNA structural changes. If a nanoparticle has a highly positive surface charge density, the DNA is likely to wrap and bend upon binding to the nanoparticle [ 13 ] (as in the case of chromatin). On the other hand, if a nanoparticle is weakly charged it will not induce dsDNA compaction. [ 9 , 10 , 15 ] Consequently, there is a transition zone from extended to compact DNA conformations which depends on the chemical nature of the nanoparticle and occurs for polycations with charges between 5 and 10. [ 9 ] While the interactions between highly charged NPs and DNA have been extensively studied, the processes that occur within the transition zone are less explored.
Compact orthogonal NMR field sensor
Gerald, II, Rex E. (Brookfield, IL); Rathke, Jerome W. (Homer Glen, IL)
2009-02-03
A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.
Mysore, Omar
In this paper, we present the first validation of the virtual source (VS) charge-based compact model for standard cell libraries and large-scale digital circuits. With only a modest number of physically meaningful parameters, ...
Compact intermediates in RNA folding
Woodson, S.A. (JHU)
2011-12-14
Large noncoding RNAs fold into their biologically functional structures via compact yet disordered intermediates, which couple the stable secondary structure of the RNA with the emerging tertiary fold. The specificity of the collapse transition, which coincides with the assembly of helical domains, depends on RNA sequence and counterions. It determines the specificity of the folding pathways and the magnitude of the free energy barriers to the ensuing search for the native conformation. By coupling helix assembly with nascent tertiary interactions, compact folding intermediates in RNA also play a crucial role in ligand binding and RNA-protein recognition.
Compact accelerator for medical therapy
Caporaso, George J.; Chen, Yu-Jiuan; Hawkins, Steven A.; Sampayan, Stephen E.; Paul, Arthur C.
2010-05-04
A compact accelerator system having an integrated particle generator-linear accelerator with a compact, small-scale construction capable of producing an energetic (.about.70-250 MeV) proton beam or other nuclei and transporting the beam direction to a medical therapy patient without the need for bending magnets or other hardware often required for remote beam transport. The integrated particle generator-accelerator is actuable as a unitary body on a support structure to enable scanning of a particle beam by direction actuation of the particle generator-accelerator.
Thermodynamic instabilities in dense asymmetric nuclear matter and in compact stars
NASA Astrophysics Data System (ADS)
Lavagno, A.; Drago, A.; Pagliara, G.; Pigato, D.
2014-07-01
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.
A Compact Pulsed Power Generator for Capillary Pinch Experiments
NASA Astrophysics Data System (ADS)
Shukla, R.; Pulsed Power Group
2006-01-01
A compact pulsed power system is designed for conducting capillary pinch experiments for production of coherent electromagnetic radiations. The reported Pulsed power system is made very compact as well as portable by using solid dielectric pulse forming line. The system consists of a tesla transformer, which is of helical secondary and cylindrical-sheet single-turn primary. Tesla charges a pulse forming line made of cascade of 50 ohm transition lines, which are of high wattage as well as high voltage ratings under pulsed operation. The net impedance of this cable cascade is such that it is matched for a designed load, which is designed to operate at 250kV for 100ns pulse duration.
Properties of dynamically compacted WIPP salt
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
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.
Compact CFB: The next generation CFB boiler
Utt, J.
1996-12-31
The next generation of compact circulating fluidized bed (CFB) boilers is described in outline form. The following topics are discussed: compact CFB = pyroflow + compact separator; compact CFB; compact separator is a breakthrough design; advantages of CFB; new design with substantial development history; KUHMO: successful demo unit; KUHMO: good performance over load range with low emissions; KOKKOLA: first commercial unit and emissions; KOKKOLA: first commercial unit and emissions; compact CFB installations; next generation CFB boiler; grid nozzle upgrades; cast segmented vortex finders; vortex finder installation; ceramic anchors; pre-cast vertical bullnose; refractory upgrades; and wet gunning.
Detonation performance of high-dense BTF charges
NASA Astrophysics Data System (ADS)
Dolgoborodov, Alexander; Brazhnikov, Michael; Makhov, Michael; Gubin, Sergey; Maklasova, Irina
2013-06-01
New experimental data on detonation wave parameters and explosive performance for benzotrifuroxan (BTF) are presented. Optical pyrometry was applied in order to measure the temperature and pressure of BTF detonation products. Chapman-Jouguet pressure and temperature were obtained as following: 33.8 GPa and 3990 K; 34.5 GPa and 4170 K (initial charge densities 1.82 and 1.84 g/cc respectively), the polytropic exponent was estimated as 2.8. The heat of explosion and acceleration ability were measured also. The results of calorimetric measurements performed in bomb calorimeter indicate that BTF slightly surpasses HMX in the heat of explosion. However BTF is inferior to HMX in the acceleration ability, measured by the method of copper casing expansion. It is also considered the hypothesis of formation of nanocarbon particles in detonation products directly behind the detonation front and influence of this processes on the temperature-time history in detonation products. The results of calculations with in view of formation of liquid nanocarbon in products of a detonation also are presented.
Compact color schlieren optical system
NASA Technical Reports Server (NTRS)
Buchele, Donald R.; Griffin, Devon W.
1993-01-01
A compact optical system for use with rainbow schlieren deflectometry is described. Both halves of the optical system consist of well-corrected telescopes whose refractive elements are all from manufacturer's stock catalogs, with the reflective primary being a spherical surface. As a result, the system is relatively easy to construct and meets the requirement of long focal length for quantitative rainbow schlieren measurements.
The Compact Project: Final Report.
ERIC Educational Resources Information Center
National Alliance of Business, Inc., Washington, DC.
The National Alliance of Business (NAB) surveyed the 12 sites that participated in the Compact Project to develop and implement programs of business-education collaboration. NAB studied start-up activities, key players, conditions for collaboration, accomplishments, challenges, and future plans. Program outcomes indicated that building successful…
Laser driven compact ion accelerator
Tajima, Toshiki
2005-03-15
A laser driven compact ion source including a light source that produces an energy pulse, a light source guide that guides the energy pulse to a target and produces an ion beam. The ion beam is transported to a desired destination.
Mesoscale Simulations of Power Compaction
Lomov, I; Fujino, D; Antoun, T; Liu, B
2009-08-06
Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.
Conformational properties of compact polymers
NASA Astrophysics Data System (ADS)
Bohn, Manfred; Heermann, Dieter W.
2009-05-01
Monte Carlo simulations of coarse-grained polymers provide a useful tool to deepen the understanding of conformational and statistical properties of polymers both in physical as well as in biological systems. In this study we sample compact conformations on a cubic L ×L×L lattice with different occupancy fractions by modifying a recently proposed algorithm. The system sizes studied extend up to N =256 000 monomers, going well beyond the limits of older publications on compact polymers. We analyze several conformational properties of these polymers, including segment correlations and screening of excluded volume. Most importantly we propose a scaling law for the end-to-end distance distribution and analyze the moments of this distribution. It shows universality with respect to different occupancy fractions, i.e., system densities. We further analyze the distance distribution between intrachain segments, which turns out to be of great importance for biological experiments. We apply these new findings to the problem of chromatin folding inside interphase nuclei and show that—although chromatin is in a compacted state—the classical theory of compact polymers does not explain recent experimental results.
Compact Circuit Preprocesses Accelerometer Output
NASA Technical Reports Server (NTRS)
Bozeman, Richard J., Jr.
1993-01-01
Compact electronic circuit transfers dc power to, and preprocesses ac output of, accelerometer and associated preamplifier. Incorporated into accelerometer case during initial fabrication or retrofit onto commercial accelerometer. Made of commercial integrated circuits and other conventional components; made smaller by use of micrologic and surface-mount technology.
COMPACT LIE GROUPS NICHOLAS ROUSE
May, J. Peter
COMPACT LIE GROUPS NICHOLAS ROUSE Abstract. The first half of the paper presents the basic definitions and results necessary for investigating Lie groups. The primary examples come from the matrix, and Submersions 3 3. Lie Groups 5 4. Group Representations 8 5. Haar Measure and Applications 9 6. The Peter
Typedirected List Compaction Nobuaki Yoshida
Â nipulation in time and space. In this paper, we present one such method, typeÂdirected list compaction preliminary experiment shows approximately 5Â13% improvement in execution time by our method even, they enable flexible and highÂlevel manipulation of recursively defined data structures. However
Higgsless superconductivity from topological defects in compact BF terms
NASA Astrophysics Data System (ADS)
Diamantini, M. Cristina; Trugenberger, Carlo A.
2015-02-01
We present a new Higgsless model of superconductivity, inspired from anyon superconductivity but P- and T-invariant and generalisable to any dimension. While the original anyon superconductivity mechanism was based on incompressible quantum Hall fluids as average field states, our mechanism involves topological insulators as average field states. In D space dimensions it involves a (D - 1)-form fictitious pseudovector gauge field which originates from the condensation of topological defects in compact low-energy effective BF theories. In the average field approximation, the corresponding uniform emergent charge creates a gap for the (D - 2)-dimensional branes via the Magnus force, the dual of the Lorentz force. One particular combination of intrinsic and emergent charge fluctuations that leaves the total charge distribution invariant constitutes an isolated gapless mode leading to superfluidity. The remaining massive modes organise themselves into a D-dimensional charged, massive vector. There is no massive Higgs scalar as there is no local order parameter. When electromagnetism is switched on, the photon acquires mass by the topological BF mechanism. Although the charge of the gapless mode (2) and the topological order (4) are the same as those of the standard Higgs model, the two models of superconductivity are clearly different since the origins of the gap, reflected in the high-energy sectors are totally different. In 2D this type of superconductivity is explicitly realised as global superconductivity in Josephson junction arrays. In 3D this model predicts a possible phase transition from topological insulators to Higgsless superconductors.
Compaction in the Bushveld Complex
NASA Astrophysics Data System (ADS)
Boorman, S.; Boudreau, A.
2003-12-01
Compaction in the mush zone of a crystallizing chamber is a model for fractionation, whereby evolved interstitial liquid expelled from the compacting crystal pile is returned to the magma chamber. If compaction was important during crystallization of the Lower and Critical Zones of the Bushveld Complex, certain textural features are expected; and, these features should correlate to position in the section, as well as to the number of mineral phases present. We report on a spectrum of textural data for 30 samples form the Lower and Critical Zones of the Bushveld Complex. Crystal Size Distributions (CSDs) are a semi-log plot of population density against crystal size, and provide information about magmatic processes such as crystal accumulation, removal and aging. Changes to the magmatic system are reflected in the shape of the CSD plot. CSDs of Bushveld rocks show a log-linear trend overturned at smaller grain sizes, a result consistent with both crystal aging, wherein larger grains grow at the expense of small ones in the crystallizing pile, and melt migration, where nucleation is suppressed by the loss of late melt fractions. CSD slope and intercept data vary with stratigraphy. Slopes in the Critical Zone are steeper, indicating less recrystallization and less of a compaction effect. In contrast, slopes in the Lower Zone are shallower, a result consistent with slower cooling and a greater compaction/recrystallization effect. Likewise, lower CSD intercepts are associated with the shallower slopes of the lower zone and vice versa. The extent of foliation is measured as alignment factor (AF), determined by orientation statistics of the major axes of the grains of interest. AF decreases with stratigraphic height and foliation is best developed in the nearly monomineralic harzburgite of the Lower Zone (AF avg=64). At the Lower Zone-Critical Zone transition, plagioclase content increases, decreasing bulk density and thus, the systems ability to accommodate compaction (Upper Critical Zone AF avg=57). There is a positive correlation between the quality of the foliation and mineral aspect ratio, suggesting that recrystallization (crystal aging) demonstrated by CSD plots occurred in a regime of uniaxial stress, wherein selective grain resorption of unfavorably oriented grains and uneven crystal growth results in grains with high aspect ratios. Spatial distribution pattern (SDP) analysis is used to determine the framework structure of spheres in 3-D. Results of R-value analysis (based on nearest neighbor statistics, (Jerram et al., 1996)) are plotted against porosity to compare Bushveld data against fields for touching and non-touching framework structures, and clustered v. ordered crystal distributions. As the Bushveld minerals are not spheres, the applicability of the field boundaries is questionable. Bushveld data form a trend that is coincident with the trend defined either by variable extents of size sorting or by the deformational compaction of spheres. A correlation on a plot of R-value versus aspect ratio clarifies that trend observed on the spatial distribution plot is due to deformational compaction. Phosphorous is a proxy for trapped liquid fraction because it is incompatible in all major phases: it indicates the extent to which late melt has been expelled. Depletion of P in the Lower Zone, where mineral alignment is highest and compaction most efficient, agrees with the hypothesis that compaction was important in redistributing trace elements. Residual porosity calculations based on Y show porosity of 5% in the Lower Zone and 20% in the Upper Critical Zone. R-values plotted against the residual porosity produce a positive trend, relating decreased porosity to grain distribution. Jerram et al., 1996 Contrib. Min. Pet. 125, 60-74.
The Design of a Compact Rfq Neutron Generator
NASA Astrophysics Data System (ADS)
Hamm, R. W.; Becker, R.
2014-02-01
The output and target lifetime of a conventional electrostatic neutron generator are limited by the voltage stand-off capability and the acceleration of molecular species from the ion source. As an alternative, we suggest that the deuterium beam achievable from a compact high intensity ECR source can be injected directly into a compact RFQ to produce a more efficient compact neutron production system. Only the d+ ions are accelerated by the RFQ, which can also produce much higher output energies than electrostatic systems, resulting in a higher neutron output with a longer target lifetime. The direct injection of the beam makes the system more compact than the multielement, electrostatic systems typically used for extraction of the beam and subsequent transport and matching into the RFQ. We have designed and optimized a combined extraction/matching system for a compact high current deuterium ECR ion source injected into a high frequency RFQ structure, allowing a beam of about 12 mA of d+ ions to be injected at a modest ion source voltage of 25 kV. The end wall of the RFQ resonator serves as the ground electrode for the ion source, resembling DPI (direct plasma injection). For this design, we used the features of the code IGUN to take into account the electrostatic field between the ion source and the RFQ end wall, the stray magnetic field of the ECR source, the defocusing space charge of the low energy deuteron beam, and the rf focusing in the fringe field between the RFQ vanes and the RFQ flange.
A tandem-based compact dual-energy gamma generator
Persaud, A.; Kwan, J. W.; Leitner, M.; Leung, K.-N.; Ludewigt, B.; Tanaka, N.; Waldron, W.; Wilde, S. [E. O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Antolak, A. J.; Morse, D. H.; Raber, T. [Sandia National Laboratories, Livermore, California 94550 (United States)
2010-02-15
A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.
Tank farms compacted low level waste
Waters, M.S., Westinghouse Hanford
1996-07-01
This report describes the process of Low Level Waste (LLW) volume reduction by compaction. Also included is the data used for characterization of LLW destined for compaction. Scaling factors (ratios) are formed based on data contained in this report.
Combined Velocity/Charge-To-Mass-Ratio Analyzer
NASA Technical Reports Server (NTRS)
Chutjian, Ara; Orient, Otto J.; Bernius, Mark T.; Hodges, R. Richard
1992-01-01
Instrument analyzes ions according to velocity and ratio of mass to electric charge. State-of-the-art combination of two instruments: time-of-flight analyzer and electrostatic analyzer functioning as mass spectrometer. Features include compactness, light weight, and low power. Terrestrial versions useful in chemical analysis, chromatography, and analysis of plasmas.
Designing of electrode for high energy charged particle acceleration
Basanta Kumar Das; A. Shyam
2010-01-01
Vacuum insulation plays an important role in charged particle acceleration. We are making one compact size neutron generator in our lab. For this purpose the deuterium ions are formed in a penning ion source and extracted along the axis of the electrode arrangement. For neutron generation from D-T reaction, the deuterium ions are to be accelerated up to ~ 100KeV
Invariant distributions on compact homogeneous spaces
Gorbatsevich, V V [Moscow State Aviation Technological University, Moscow (Russian Federation)
2013-12-31
In this paper, we study distributions on compact homogeneous spaces, including invariant distributions and also distributions admitting a sub-Riemannian structure. We first consider distributions of dimension 1 and 2 on compact homogeneous spaces. After this, we study the cases of compact homogeneous spaces of dimension 2, 3, and 4 in detail. Invariant distributions on simply connected compact homogeneous spaces are also treated. Bibliography: 18 titles.
Code of Federal Regulations, 2010 CFR
2010-01-01
...Agriculture 2 2010-01-01 2010-01-01 false Compact. 51.572 Section 51.572 Agriculture Regulations...States Standards for Celery Definitions § 51.572 Compact. Compact means that the branches on the stalk are fairly...
28 CFR 2.107 - Interstate Compact.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 2010-07-01 false Interstate Compact. 2.107 Section 2.107 Judicial...and Parolees § 2.107 Interstate Compact. (a) Pursuant to D.C. Code...CSOSA), or his designee, shall be the Compact Administrator with regard to the...
Technology of compact fusion-reactor concepts
Krakowski, R.A.; Glancy, J.E.; Dabiri, A.E.
1982-01-01
An identification of future engineering needs of compact, high-power-density approaches to fusion power is presented. After describing a rationale for the compact approach and a number of compact fusion reactors, key technology needs are assessed relative to the similar needs of the conventional tokamak in order to emphasize differences in required technology with respect to the well-documented mainline approaches.
COMPACT WELL-BOUNDED OPERATORS CHENG QINGPING
Doust, Ian
COMPACT WELL-BOUNDED OPERATORS CHENG QINGPING School of Mathematical and Physical Sciences, Murdoch. Every compact well-bounded operator has a representation as a lin- ear combination of disjoint that the converse of this result holds, thus characterizing compact well-bounded operators. We also apply
Use of a BCD for compaction control
Li, Yanfeng
2005-11-01
.1 Soil Compaction............................................................................................1 1.2 Current Soil Compaction Control Apparatus................................................2 1.3 Current Status of Soil Compaction Control..........................................................................................9 2.1 Density or Modulus? .....................................................................................9 2.2 Introduction to Soil Modulus ......................................................................12 2.3 Soil Modulus Measurement...
Approximation by polynomials on quaternionic compact sets
NASA Astrophysics Data System (ADS)
Gal, S. G.; Sabadini, I.
2015-09-01
In this paper we obtain several extensions to the quaternionic setting of some results concerning the approximation by polynomials of functions continuous on a compact set and holomorphic in its interior. The results include approximation on compact starlike sets and compact axially symmetric sets. The cases of some concrete particular sets are described in details, including quantitative estimates too.
Electron Strippers for Compact Neutron Generators
NASA Astrophysics Data System (ADS)
Terai, K.; Tanaka, N.; Kisaki, M.; Tsugawa, K.; Okamoto, A.; Kitajima, S.; Sasao, M.; Takeno, T.; Antolak, A. J.; Leung, K. N.; Wada, M.
2011-09-01
The next generation of compact tandem-type DD or DT neutron generators requires a robust electron stripper with high charge exchange efficiency. In this study, stripping foils of various types were tested, and the H- to H+ conversion efficiency, endurance to the heat load, and durability were investigated in terms of suitability in the tandem-type neutron generator. In the experiments, a H- beam was accelerated to about 180 keV, passes through a stripping foil, and produces a mixed beam of H-, H0, and H+. These ions were separated by an electric field, and detected by a movable Faraday cup to determine the conversion efficiency. The experimental results using thin foils of diamond-like carbon, gold, and carbon nano-tubes revealed issues on the robustness. As a new concept, a H- beam was injected onto a metal surface with an oblique angle, and reflected H+ ions are detected. It was found that the conversion efficiency, H+ fraction in the reflected particles, depends on the surface condition, with the maximum value of about 90%.
Electron Strippers for Compact Neutron Generators
Terai, K.; Tanaka, N.; Kisaki, M.; Tsugawa, K.; Okamoto, A.; Kitajima, S.; Sasao, M.; Takeno, T.; Antolak, A. J.; Leung, K. N.; Wada, M.
2011-09-26
The next generation of compact tandem-type DD or DT neutron generators requires a robust electron stripper with high charge exchange efficiency. In this study, stripping foils of various types were tested, and the H{sup -} to H{sup +} conversion efficiency, endurance to the heat load, and durability were investigated in terms of suitability in the tandem-type neutron generator. In the experiments, a H{sup -} beam was accelerated to about 180 keV, passes through a stripping foil, and produces a mixed beam of H{sup -}, H{sup 0}, and H{sup +}. These ions were separated by an electric field, and detected by a movable Faraday cup to determine the conversion efficiency. The experimental results using thin foils of diamond-like carbon, gold, and carbon nano-tubes revealed issues on the robustness. As a new concept, a H{sup -} beam was injected onto a metal surface with an oblique angle, and reflected H{sup +} ions are detected. It was found that the conversion efficiency, H{sup +} fraction in the reflected particles, depends on the surface condition, with the maximum value of about 90%.
Analysis of compact and sealed RPCs feasibility
NASA Astrophysics Data System (ADS)
Morales, M.; Rodríguez-Sánchez, J. L.; Garzón, J. A.
2013-03-01
In this article, the feasibility of developing compact and portable float glass sealed Resistive Plate Chambers, sRPCs, is analyzed. For this purpose, several small (80 cm2) sealed chambers have been constructed using inexpensive materials like windows float glass, copper tape and nylon fishing line. For the sake of simplicity, during this first development stage, only R134a has been used as ionizing gas. In order to distinguish gas leakage from internal gas degradation, a couple of sRPCs were tested inside a box with flowing gas: one with R134a and another with N2. Prompt charge, signal rising slope and operational current were used to assess chambers performance degradation during a two-week period. Regarding these variables, small leakages were spotted as the main reason for the performance degradation observed after about one week of steady operation at the sRPC working in N2 environment. The sRPC working in an R134a environment did not show any significative degradation during the whole test. A discussion on merits and limitations of the proposed design is provided.
Gravitational collapse of charged scalar fields
NASA Astrophysics Data System (ADS)
Torres, Jose M.; Alcubierre, Miguel
2014-09-01
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|
Gravitational collapse of charged scalar fields
Jose M. Torres; Miguel Alcubierre
2014-07-29
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|
Anisotropic charged analogue of Heintzmann's solution
NASA Astrophysics Data System (ADS)
Pradhan, N.; Pant, Neeraj
2015-03-01
We present an anisotropic charged analogue of Heintzmann's (Z. Phys. 228:489, 1969) solution of the general relativistic field equations in curvature coordinates by using simple form of electric intensity E and pressure anisotropy factor ? that involve charge parameter K and anisotropy parameter ? respectively. Our solution is well behaved in all respects for all values of X lying in the range 0< X?1.1, ? lying in the range 0? ??6.2, K lying in the range 0< K?9.7 and Schwarzschild compactness parameter " u" lying in the range 0< u?0.391. Since our solution is well behaved for a wide ranges of the parameters, we can model many different types of ultra-cold compact stars like quark stars and neutron stars. We present some models of super dense quark star and neutron stars corresponding to X=0.1, ?=1 and K=3. By assuming surface density of quark star, ? b =4.6888×1014 g cm-3 the mass and radius are 1.271 M ?, 10.09 km respectively. For ? b =2.7×1014 g cm-3 the mass and radius of neutron star are 1.675 M ?, 13.297 km respectively. The well behaved class of relativistic stellar models obtained in this work might have astrophysical significance in the study of more realistic internal structure of compact stars.
The Atacama Compact Array (ACA)
NASA Astrophysics Data System (ADS)
Iguchi, Satoru; Morita, Koh-Ichiro; Sugimoto, Masahiro; Vila Vilaró, Baltasar; Saito, Masao; Hasegawa, Tetsuo; Kawabe, Ryohei; Tatematsu, Ken'ichi; Seiichi, Seiichi; Kiuchi, Hitoshi; Okumura, Sachiko K.; Kosugi, George; Inatani, Junji; Takakuwa, Shigehisa; Iono, Daisuke; Kamazaki, Takeshi; Ogasawara, Ryusuke; Ishiguro, Masato
2009-02-01
For realizing high fidelity of imaging with mosaicing observations, the Atacama Large Millimeter/submillimeter Array (ALMA) consists of a homogeneous array of 12 m antennas (12 m Array) and the Atacama Compact Array (ACA) in order to cover all spatial frequency Fourier components of the brightness distribution of observed sources. The array is located at an altitude site of about 5000m with an operating wavelength range of 0.3 to 3mm. ACA is an array composed of four 12 m dishes [TP (Total Power) Array] and twelve 7 m dishes (7 m Array). The 7 m Array has a very compact configuration to take short-baseline data corresponding to the low spatial frequency Fourier components. The 7 m Array has two configurations extended over 30--50m to avoid shadowing at low elevation. The scientific importances and operation concepts of ACA, and the system design of ACA and its performance are presented in this paper.
Compact torus studies: Final report
Morse, E.C.
1987-06-01
The compact torus (CT) device has been proposed for use in some applications which are of interest in Laboratory programs in the areas of pulsed power and inertial confinement fusion. These applications involve compression and acceleration of CT plasmas. The RACE (Ring Accelerator Experiment) experimental program at Livermore has been initiated to study these applications. The work reported here involves studies of plasma physics and other aspects of these compact torus applications. The studies conducted identify specific problem areas associated with the CT device and examine these areas in some detail. This report contains studies of three particular problem areas of the CT applications. These three areas are: the general nonlinear properties of the CT as a magnetohydrodynamic (MHD) equilibrium, particle simulation of the compression of the CT, with a focus on the non-MHD effects, and nonlinear RF interaction problems in the CT.
Recent Results in Charged-Composite Particle Scattering
Alt, E O
1997-01-01
A brief overview is given of some recent advances in charged-composite particle scattering. On the theoretical side, I address the three-charged particle wave function asymptotics, the nonperturbative investigation of the long-range behaviour of the optical potential, and the question of the compactness of the kernels of the momentum space integral equations for three charged particles. Among the more practical developments, I report on results of numerical calculations of so-called "triangle" amplitudes, a new, simple and very efficient higher-energy approximation for the latter, and a breakthrough in the quantitative treatment of Coulomb effects in proton-deuteron elastic scattering with realistic nuclear potentials.
Recent Results in Charged-Composite Particle Scattering
Erwin O. Alt
1997-10-20
A brief overview is given of some recent advances in charged-composite particle scattering. On the theoretical side, I address the three-charged particle wave function asymptotics, the nonperturbative investigation of the long-range behaviour of the optical potential, and the question of the compactness of the kernels of the momentum space integral equations for three charged particles. Among the more practical developments, I report on results of numerical calculations of so-called "triangle" amplitudes, a new, simple and very efficient higher-energy approximation for the latter, and a breakthrough in the quantitative treatment of Coulomb effects in proton-deuteron elastic scattering with realistic nuclear potentials.
Charge-coupled computing for focal plane image preprocessing
NASA Astrophysics Data System (ADS)
Fossum, Eric R.
1987-09-01
A new class of CCDs, charge-coupled-computing devices, are described which perform arithmetic functions such as addition, subtraction, and magnitude comparison in the charge domain. These compact circuits are insensitive to rail voltages. A prototype charge-coupled computer has been fabricated by combining these devices in conjunction with input, output, and analog memory circuits. The possibility of forming a large array of computers on a single chip for spatially parallel image preprocessing (with application to real-time mobile robot vision systems) is discussed.
Compact portable diffraction moire interferometer
Deason, Vance A. (Shelley, ID); Ward, Michael B. (Idaho Falls, ID)
1989-01-01
A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.
Compact portable diffraction moire interferometer
Deason, V.A.; Ward, M.B.
1988-05-23
A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.
Compact Color Schlieren Optical System
NASA Technical Reports Server (NTRS)
Buchele, Donald R.; Griffin, Devon W.
1996-01-01
Compact, rugged optical system developed for use in rainbow schlieren deflectometry. Features unobscured telescope with focal-length/aperture-width ratio of 30. Made of carefully selected but relatively inexpensive parts. All of lenses stock items. By-product of design is optical system with loose tolerances on interlens spacing. One of resulting advantages, insensitivity to errors in fabrication of optomechanical mounts. Another advantage is ability to compensate for some of unit-to-unit variations inherent in stock lenses.
CIT (Compact Ignition Tokamak) fueling
Houlberg, W.A.
1988-01-01
A series of viewgraphs present issues related to the conceptual design of the Compact Ignition Tokamak. The presentation includes discussions of fueling issues, pellet injector technology, pellet ablation and penetration, particle confinement, and fueling scenarios. The author concludes that existing technology should be used for the basic injector while several options for enhanced velocity injectors are under development; adequate models exist for pellet ablation; and improvements in confinement models can come from the TFTR and JET programs. (DWL)
Compact Infrared Continuous Zoom Telescope
NASA Astrophysics Data System (ADS)
Roberts, M.; Campbell, D. R. J.
1983-06-01
In the field of infrared optics (8-12 microns) there is an increasing requirement for continuous zoom telescopes operating with scanner systems. To date, zoom telescopes have for some applications been precluded due to excessive length. An exercise was undertaken to explore the possibility of length reduction. The study resulted in the design of a compact, high performance IR zoom telescope. This design and its development will be described including achromatisation, athermalisation and tolerancing aspects.
Compact magnetic energy storage module
Prueitt, Melvin L. (Los Alamos, NM)
1994-01-01
A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module.
Compact magnetic energy storage module
Prueitt, M.L.
1994-12-20
A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.
Compact planar microwave blocking filters
NASA Technical Reports Server (NTRS)
U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor)
2012-01-01
A compact planar microwave blocking filter includes a dielectric substrate and a plurality of filter unit elements disposed on the substrate. The filter unit elements are interconnected in a symmetrical series cascade with filter unit elements being organized in the series based on physical size. In the filter, a first filter unit element of the plurality of filter unit elements includes a low impedance open-ended line configured to reduce the shunt capacitance of the filter.
Compaction Waves in Granular HMX
E. Kober; R. Menikoff
1999-01-01
Piston driven compaction waves in granular HMX are simulated with a two-dimensional continuum mechanics code in which individual grains are resolved. The constitutive properties of the grains are modeled with a hydrostatic pressure and a simple elastic-plastic model for the shear stress. Parameters are chosen to correspond to inert HMX. For a tightly packed random grain distribution (with initial porosity of 19%) we varied the piston velocity to obtain weak partly compacted waves and stronger fully compacted waves. The average stress and wave speed are compatible with the porous Hugoniot locus for uni- axial strain. However, the heterogeneities give rise to stress concentrations, which lead to localized plastic flow. For weak waves, plastic deformation is the dominant dissipative mechanism and leads to dispersed waves that spread out in time. In addition to dispersion, the granular heterogeneities give rise to subgrain spatial variation in the thermodynamic variables. The peaks in the temperature fluctuations, known as hot spots, are in the range such that they are the critical factor for initiation sensitivity.
Compact Stellarator Path to DEMO
NASA Astrophysics Data System (ADS)
Lyon, J. F.
2007-11-01
Issues for a DEMO reactor are sustaining an ignited/high-Q plasma in steady state, avoiding disruptions and large variations in power flux to the wall, adequate confinement of thermal plasma and alpha-particles, control of a burning plasma, particle and power handling, etc. Compact stellarators have key advantages -- steady-state high-plasma-density operation without external current drive or disruptions, stability without a close conducting wall or active feedback systems, and low recirculating power -- in addition to moderate plasma aspect ratio, good confinement, and high-beta potential. The ARIES-CS study established that compact stellarators can be competitive with tokamaks as reactors. Many of the issues for a compact stellarator DEMO can be answered using results from large tokamaks, ITER D-T experiments and fusion materials, technology and component development programs, in addition to stellarators in operation, under construction or in development. However, a large next-generation stellarator will be needed to address some physics issues: size scaling and confinement at higher parameters, burning plasma issues, and operation with a strongly radiative divertor. Technology issues include simpler coils, structure, and divertor fabrication, and better cost information.
Federal Register 2010, 2011, 2012, 2013, 2014
2012-04-17
...the Compact Council for the National Crime Prevention and Privacy Compact; Correction...the date and location of the National Crime Prevention and Privacy Compact Council (Council) created by the National Crime Prevention and Privacy Compact Act...
Compact Video Microscope Imaging System Implemented in Colloid Studies
NASA Technical Reports Server (NTRS)
McDowell, Mark
2002-01-01
Long description Photographs showing fiber-optic light source, microscope and charge-coupled discharge (CCD) camera head connected to camera body, CCD camera body feeding data to image acquisition board in PC, and Cartesian robot controlled via PC board. The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. CMIS can be used in situ with a minimum amount of user intervention. This system can scan, find areas of interest in, focus on, and acquire images automatically. Many multiple-cell experiments require microscopy for in situ observations; this is feasible only with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control. The software also has a user-friendly interface, which can be used independently of the hardware for further post-experiment analysis. CMIS has been successfully developed in the SML Laboratory at the NASA Glenn Research Center and adapted for use for colloid studies and is available for telescience experiments. The main innovations this year are an improved interface, optimized algorithms, and the ability to control conventional full-sized microscopes in addition to compact microscopes. The CMIS software-hardware interface is being integrated into our SML Analysis package, which will be a robust general-purpose image-processing package that can handle over 100 space and industrial applications.
A compact LED-based module for DNA capillary electrophoresis
NASA Astrophysics Data System (ADS)
Hurth, C.; Lenigk, R.; Zenhausern, F.
2008-11-01
A setup consisting of a bifurcated optical fiber made from high-transmission fused-silica cores with relatively high numerical apertures (NA=0.22), high-power cyan light-emitting diodes (LEDs) and Peltier cooling elements controlled by a proportional-integrative-derivative (PID) module is introduced to replace bulky, power- consuming lasers conventionally used in laser induced fluorescence (LIF) microchip capillary electrophoresis (?CE). The output fiber beam size, divergence, power distribution and power stability over time are documented. A modified epifluorescence microscope arrangement is used in conjunction with a compact fixed spectrometer aligned with a cooled charge-coupled device (CCD) camera for added sensitivity. Fluorescent dyes such as fluorescein, 6-carboxyfluorescein (6-FAM) and rhodamine B can be detected in cyclic olefin copolymer (COC) and glass microchannels at submicromolar levels. A single-stranded DNA oligonucleotide (10-mer) labeled with 6-FAM is also detected with reasonable signal-to-noise ratio when electrophoretically migrated at 100 V/cm. The compact LED excitation system presented herein will allow using capillary electrophoresis for DNA detection in compact mobile devices.
Modelling IHE Main Charge Initiation Trains based on HMX and TATB based Booster Charges
NASA Astrophysics Data System (ADS)
Drake, Rodney; Maisey, Matthew
2015-06-01
There is always a requirement to reduce the size of initiation trains. However, as the size is reduced the performance characteristics may be compromised. To enable compact and robust initiation trains to be designed requires a detailed science-based understanding of the processes (for example, growth to detonation) which determine the performance characteristics. A numerical modelling study has been performed to understand the designs of initiation trains comprising flyer plate detonator, booster charge and an IHE main charge. The effect of the flyer plate diameter on the distance required to establish uniformly diverging detonation waves in HMX and TATB based booster charges has been studied. Numerical simulations have also examined the effect of the relative sizes of the booster and IHE main charge on the distance required for a stable detonation front to be established in the main charge for both HMX and TATB based booster charges. The implications of the numerical simulations are discussed in terms of the design of initiation trains for IHE main charge systems.
Intense Pulsed Neutron Emission from a Compact Pyroelectric Driven Accelerator
Tang, V; Meyer, G; Falabella, S; Guethlein, G; Sampayan, S; Kerr, P; Rusnak, B; Morse, J
2008-10-08
Intense pulsed D-D neutron emission with rates >10{sup 10} n/s during the pulse, pulse widths of {approx}100's ns, and neutron yields >10 k per pulse are demonstrated in a compact pyroelectric accelerator. The accelerator consists of a small pyroelectric LiTaO{sub 3} crystal which provides the accelerating voltage and an independent compact spark plasma ion source. The crystal voltage versus temperature is characterized and compare well with theory. Results show neutron output per pulse that scales with voltage as V{approx}1.7. These neutron yields match a simple model of the system at low voltages but are lower than predicted at higher voltages due to charge losses not accounted for in the model. Interpretation of the data against modeling provides understanding of the accelerator and in general pyroelectric LiTaO{sub 3} crystals operated as charge limited negative high voltage targets. The findings overall serve as the proof-of-principle and basis for pyroelectric neutron generators that can be pulsed, giving peak neutron rates orders of magnitude greater than previous work, and notably increase the potential applications of pyroelectric based neutron generators.
Compact pulse forming line using barium titanate ceramic material
NASA Astrophysics Data System (ADS)
Kumar Sharma, Surender; Deb, P.; Shukla, R.; Prabaharan, T.; Shyam, A.
2011-11-01
Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO3) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? 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.
Compact pulse forming line using barium titanate ceramic material.
Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A
2011-11-01
Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. PMID:22129008
Charge-Coupled Computing For Focal Plane Image Preprocessing
NASA Astrophysics Data System (ADS)
Fossum, Eric R.
1988-01-01
A new class of charge-coupled devices called charge-coupled-computing devices is described. These analog circuits perform arithmetic functions such as addition, subtraction, and magnitude comparison in the charge domain. The circuits are compact and are designed to be insensitive to rail voltages, simplifying their utilization. These devices, in conjunction with input, output, and analog memory circuits, can be combined to form a simple but general-purpose and fully programmable charge-coupled computer. A prototype charge-coupled computer has been fabricated and tested. Prospects for forming a large array of computers (e.g., 1000 to 10,000) on a single chip for spatially parallel image preprocessing are discussed. Such image plane preprocessing of data would find use in real-time mobile robot vision systems, in which low power, lightweight computing is critical for economical viability.
Compaction of Space Mission Wastes
NASA Technical Reports Server (NTRS)
Fisher, John; Pisharody, Suresh; Wignarajah, K.
2004-01-01
The current solid waste management system employed on the International Space Station (ISS) consists of compaction, storage, and disposal. Wastes such plastic food packaging and trash are compacted manually and wrapped in duct tape footballs by the astronauts. Much of the waste is simply loaded either into the empty Russian Progress vehicle for destruction on reentry or into Shuttle for return to Earth. This manual method is wasteful of crew time and does not transition well to far term missions. Different wastes onboard spacecraft vary considerably in their characteristics and in the appropriate method of management. In advanced life support systems for far term missions, recovery of resources such as water from the wastes becomes important. However waste such as plastic food packaging, which constitutes a large fraction of solid waste (roughly 21% on ISS, more on long duration missions), contains minimal recoverable resource. The appropriate management of plastic waste is waste stabilization and volume minimization rather than resource recovery. This paper describes work that has begun at Ames Research Center on development of a heat melt compactor that can be used on near term and future missions, that can minimize crew interaction, and that can handle wastes with a significant plastic composition. The heat melt compactor takes advantage of the low melting point of plastics to compact plastic materials using a combination of heat and pressure. The US Navy has demonstrated successful development of a similar unit for shipboard application. Ames is building upon the basic approach demonstrated by the Navy to develop an advanced heat melt type compactor for space mission type wastes.
Permeability of compacting porous lavas
NASA Astrophysics Data System (ADS)
Ashwell, P. A.; Kendrick, J. E.; Lavallée, Y.; Kennedy, B. M.; Hess, K.-U.; Aulock, F. W.; Wadsworth, F. B.; Vasseur, J.; Dingwell, D. B.
2015-03-01
The highly transient nature of outgassing commonly observed at volcanoes is in part controlled by the permeability of lava domes and shallow conduits. Lava domes generally consist of a porous outer carapace surrounding a denser lava core with internal shear zones of variable porosity. Here we examine densification using uniaxial compression experiments on variably crystalline and porous rhyolitic dome lavas from the Taupo Volcanic Zone. Experiments were conducted at 900°C and an applied stress of 3 MPa to 60% strain, while monitoring acoustic emissions to track cracking. The evolution of the porous network was assessed via X-ray computed tomography, He-pycnometry, and relative gas permeability. High starting connected porosities led to low apparent viscosities and high strain rates, initially accompanied by abundant acoustic emissions. As compaction ensued, the lavas evolved; apparent viscosity increased and strain rate decreased due to strain hardening of the suspensions. Permeability fluctuations resulted from the interplay between viscous flow and brittle failure. Where phenocrysts were abundant, cracks had limited spatial extent, and pore closure decreased axial and radial permeability proportionally, maintaining the initial anisotropy. In crystal-poor lavas, axial cracks had a more profound effect, and permeability anisotropy switched to favor axial flow. Irrespective of porosity, both crystalline samples compacted to a threshold minimum porosity of 17-19%, whereas the crystal-poor sample did not achieve its compaction limit. This indicates that unconfined loading of porous dome lavas does not necessarily form an impermeable plug and may be hindered, in part by the presence of crystals.
Gravitational Waves from Compact Objects
NASA Astrophysics Data System (ADS)
Owen, Benjamin James
This thesis addresses problems in the generation and detection of gravitational waves from two types of sources: inspiraling compact binaries and rapidly rotating young neutron stars. Chapters 2 and 3 estimate the computational costs of a basic matched filtering strategy to search for inspiraling compact binaries. Chapter 2 (written in 1995) sets up the machinery for calculating costs and makes a rough estimate based on the waveforms and noise spectra available at the time. It also systematizes previously published methods of choosing the filters. Chapter 3 (written with B. S. Sathyaprakash in 1998) fine-tunes the machinery and updates the estimates of Chapter 2 using more current waveforms and noise spectra. Chapter 4 (written with Hideyuki Tagoshi and Akira Ohashi) concerns the post-Newtonian generation of gravitational waveforms from inspiraling compact binaries whose component objects spin about their own axes. It lays out a method of calculating post-Newtonian spin effects and calculates the lowest-order such effect not previously known (the second-post-Newtonian spin-orbit contribution to the waveforms in the absence of precession). Chapters 5 and 6 concern the Chandrasekhar-Friedman-Schutz (CFS) gravitational radiation instability as it applies to the r-modes of rapidly rotating young neutron stars. Chapter 5 (written with Lee Lindblom and Sharon M. Morsink) computes the viscous damping and gravitational radiation timescales of the r-modes and shows that viscosity does not suppress the CFS instability in hot young neutron stars. Chapter 6 (written with Lee Lindblom, Curt Cutler, Bernard F. Schutz, Alberto Vecchio, and Nils Andersson) computes approximate gravitational waveforms from young neutron stars spinning down due to the r-mode instability and estimates that these gravitational waves can be detected by the 'enhanced' LIGO interferometers if a suitable data analysis strategy is developed.
NASA Astrophysics Data System (ADS)
Fajt, L.; Kouba, P.; Mamedov, F.; Smolek, K.; Štekl, I.; Fojtík, P.; Hýža, M.; HÅ¯lka, J.; Jílek, K.; Sto?ek, P.; Veselý, J.; Busto, J.
2015-08-01
Suppression of radon background is one of main tasks in ultra-low background experiments. The most promising technique for suppression of radon is its adsorption on charcoal. Within the frame of the NEMO-3 experiment, radon trapping facility (RTF) was installed in Modane underground laboratory in 2004. Based on long-term experience with this facility a new compact transportable anti-radon facility was constructed in cooperation among IEAP CTU, SÚRO and ATEKO company. The device provides 20m3/h of purified air (air radon activity at the output ˜10mBq/m3). The basic features and preliminary results of anti-radon device testing are presented.
Shock compaction of molybdenum powder
NASA Technical Reports Server (NTRS)
Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.
1983-01-01
Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.
Two Piece Compaction Die Design
Coffey, Ethan N [ORNL
2010-03-01
Compaction dies used to create europium oxide and tantalum control plates were modeled using ANSYS 11.0. Two-piece designs were considered in order to make the dies easier to assemble than the five-piece dies that were previously used. The two areas of concern were the stresses at the interior corner of the die cavity and the distortion of the cavity wall due to the interference fit between the two pieces and the pressure exerted on the die during the compaction process. A successful die design would have stresses less than the yield stress of the material and a maximum wall distortion on the order of 0.0001 in. Design factors that were investigated include the inner corner radius, the value of the interference fit, the compaction force, the size of the cavity, and the outer radius and geometry of the outer ring. The results show that for the europium oxide die, a 0.01 in. diameter wire can be used to create the cavity, leading to a 0.0055 in. radius corner, if the radial interference fit is 0.003 in. For the tantalum die, the same wire can be used with a radial interference fit of 0.001 in. Also, for the europium oxide die with a 0.003 in. interference fit, it is possible to use a wire with a diameter of 0.006 in. for the wire burning process. Adding a 10% safety factor to the compaction force tends to lead to conservative estimates of the stresses but not for the wall distortion. However, when the 10% safety factor is removed, the wall distortion is not affected enough to discard the design. Finally, regarding the europium oxide die, when the cavity walls are increased by 0.002 in. per side or the outer ring is made to the same geometry as the tantalum die, all the stresses and wall distortions are within the desired range. Thus, the recommendation is to use a 0.006 in. diameter wire and a 0.003 in. interference fit for the europium oxide die and a 0.01 in. diameter wire and a 0.001 in. interference fit for the tantalum die. The dies can also be made to have the same outer geometry if desired.
Compact bilinear operators and commutators
Bé nyi, Á rpá d; Torres, Rodolfo H.
2013-07-01
. TORRES (Communicated by Michael T. Lacey) Abstract. A notion of compactness in the bilinear setting is explored. More- over, commutators of bilinear Caldero´n-Zygmund operators and multiplication by functions in a certain subspace of the space... 129.237.46.100. License or copyright restrictions may apply to redistribution; see http://www.ams.org/journal-terms-of-use 3610 A´RPA´D BE´NYI AND RODOLFO H. TORRES Ty = T (·, y) : X ? Z are required to be linear for all (fixed) x ? X, y ? Y . The two...
Compact plasmonic variable optical attenuator.
Leosson, Kristjan; Rosenzveig, Tiberiu; Hermannsson, Petur G; Boltasseva, Alexandra
2008-09-29
We demonstrate plasmonic nanowire-based thermo-optic variable optical attenuators operating in the 1525-1625 nm wavelength range. The devices have a footprint as low as 1 mm, extinction ratio exceeding 40 dB, driving voltage below 3 V, and full modulation bandwidth of 1 kHz. The polarization dependent loss is shown to be critically dependent on the nanowire geometry but devices with polarization-dependent loss as low as +/-2.5 dB PDL over most of the attenuation range have been fabricated. We propose an even more compact device design to reduce insertion loss to approximately 1 dB. PMID:18825193
Brittle and compaction creep in porous sandstone
NASA Astrophysics Data System (ADS)
Heap, Michael; Brantut, Nicolas; Baud, Patrick; Meredith, Philip
2015-04-01
Strain localisation in the Earth's crust occurs at all scales, from the fracture of grains at the microscale to crustal-scale faulting. Over the last fifty years, laboratory rock deformation studies have exposed the variety of deformation mechanisms and failure modes of rock. Broadly speaking, rock failure can be described as either dilatant (brittle) or compactive. While dilatant failure in porous sandstones is manifest as shear fracturing, their failure in the compactant regime can be characterised by either distributed cataclastic flow or the formation of localised compaction bands. To better understand the time-dependency of strain localisation (shear fracturing and compaction band growth), we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (porosity = 24%) under a constant stress (creep) in the dilatant and compactive regimes, with particular focus on time-dependent compaction band formation in the compactive regime. Our experiments show that inelastic strain accumulates at a constant stress in the brittle and compactive regimes leading to the development of shear fractures and compaction bands, respectively. While creep in the dilatant regime is characterised by an increase in porosity and, ultimately, an acceleration in axial strain to shear failure (as observed in previous studies), compaction creep is characterised by a reduction in porosity and a gradual deceleration in axial strain. The overall deceleration in axial strain, AE activity, and porosity change during creep compaction is punctuated by excursions interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence background creep strain rate, is decreased, although the inelastic strain required for a compaction band remains constant over strain rates spanning several orders of magnitude. We find that, despite the large differences in strain rate and growth rate (from both creep and constant strain rate experiments), the characteristics (geometry, thickness) of a compaction band remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactive regimes, suggest that, as for dilatant creep, compactant creep is driven by subcritical stress corrosion cracking. We highlight the attendant implications for time-dependent porosity loss, subsidence, and permeability reduction in sandstone reservoirs.
Detecting Charged Particles Using Charge Injection Devices
K. A. Fletcher; B. Apker; S. Hammond; J. Punaro; G. Surman; F. J. Marshall; J. Laine
2004-01-01
CID cameras, used for x-ray imaging on the University of Rochester's OMEGA laser system, can also be used to detect charged particles, such as those emitted in fusion reactions. The charged-particle sensitivity of CID cameras is being measured using both radioactive alpha sources and fusion reactions generated by the SUNY Geneseo 2 MV Van de Graaff accelerator. To determine the
Improving outpatient charge capture.
Gautschi, Daniel; Sanderson, Brian
2014-10-01
Hospitals can identify opportunities to enhance revenue collection by closely analyzing outpatient charge-capture data. A hospital can bolster its charge-capture analysis by performing a charge-capture process walk-through and scrutinizing subsystem links, third-party payer contracts, and electronic health record structures. The hospital then can integrate charge-integrity functions into clinical departments as needed by developing charge-reconciliation tools and reports and monitoring their utilization, and incorporating charge-reconciliation responsibilities into clinical department managers' job descriptions and goals. PMID:25647902
Magnetoelectric charge trap memory.
Bauer, Uwe; Przybylski, Marek; Kirschner, Jürgen; Beach, Geoffrey S D
2012-03-14
It is demonstrated that a charge-trapping layer placed in proximity to a ferromagnetic metal enables efficient electrical and optical control of the metal's magnetic properties. Retention of charge trapped inside the charge-trapping layer provides nonvolatility to the magnetoelectric effect and enhances its efficiency by an order of magnitude. As such, an engineered charge-trapping layer can be used to realize the magnetoelectric equivalent to today's pervasive charge trap flash memory technology. Moreover, by supplying trapped charges optically instead of electrically, a focused laser beam can be used to imprint the magnetic state into a continuous metal film. PMID:22300444
High flux compact neutron generators
Reijonen, J.; Lou, T.-P.; Tolmachoff, B.; Leung, K.-N.; Verbeke, J.; Vujic, J.
2001-06-15
Compact high flux neutron generators are developed at the Lawrence Berkeley National Laboratory. The neutron production is based on D-D or D-T reaction. The deuterium or tritium ions are produced from plasma using either a 2 MHz or 13.56 MHz radio frequency (RF) discharge. RF-discharge yields high fraction of atomic species in the beam which enables higher neutron output. In the first tube design, the ion beam is formed using a multiple hole accelerator column. The beam is accelerated to energy of 80 keV by means of a three-electrode extraction system. The ion beam then impinges on a titanium target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated. The MCNP computation code has predicted a neutron flux of {approximately}10{sup 11} n/s for the D-D reaction at beam intensity of 1.5 A at 150 kV. The neutron flux measurements of this tube design will be presented. Recently new compact high flux tubes are being developed which can be used for various applications. These tubes also utilize RF-discharge for plasma generation. The design of these tubes and the first measurements will be discussed in this presentation.
NASA Astrophysics Data System (ADS)
Sešek, Aleksander; Å vigelj, Andrej; Trontelj, Janez
2015-03-01
The objective of this paper is the development of a compact low cost imaging THz system, usable for observation of the objects near to the system and also for stand-off detection. The performance of the system remains at the high standard of more expensive and bulkiest system on the market. It is easy to operate as it is not dependent on any fine mechanical adjustments. As it is compact and it consumes low power, also a portable system was developed for stand-off detection of concealed objects under textile or inside packages. These requirements rule out all optical systems like Time Domain Spectroscopy systems which need fine optical component positioning and requires a large amount of time to perform a scan and the image capture pixel-by-pixel. They are also almost not suitable for stand-off detection due to low output power. In the paper the antenna - bolometer sensor microstructure is presented and the THz system described. Analysis and design guidelines for the bolometer itself are discussed. The measurement results for both near and stand-off THz imaging are also presented.
Compact submanifolds supporting singular interactions
Kaynak, Burak Tevfik, E-mail: burak.kaynak@boun.edu.tr; Teoman Turgut, O., E-mail: turgutte@boun.edu.tr
2013-12-15
A quantum particle moving under the influence of singular interactions on embedded surfaces furnish an interesting example from the spectral point of view. In these problems, the possible occurrence of a bound-state is perhaps the most important aspect. Such systems can be introduced as quadratic forms and generically they do not require renormalization. Yet an alternative path through the resolvent is also beneficial to study various properties. In the present work, we address these issues for compact surfaces embedded in a class of ambient manifolds. We discover that there is an exact bound state solution written in terms of the heat kernel of the ambient manifold for a range of coupling strengths. Moreover, we develop techniques to estimate bounds on the ground state energy when several surfaces, each of which admits a bound state solution, coexist. -- Highlights: •Schrödinger operator with singular interactions supported on compact submanifolds. •Exact bound-state solution in terms of the heat kernel of the ambient manifold. •Generalization of the variational approach to a collection of submanifolds. •Existence of a lower bound for a unique ground state energy.
Compacted carbon for electrochemical cells
Greinke, Ronald Alfred (Medina, OH); Lewis, Irwin Charles (Strongsville, OH)
1997-01-01
This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (i) an x-ray density of at least 2.00 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 47%; and (b) graphite having the following properties: (i) an x-ray density of at least 2.20 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counterelectrode.
Compacted carbon for electrochemical cells
Greinke, R.A.; Lewis, I.C.
1997-10-14
This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (1) an x-ray density of at least 2.00 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 47%; and (b) graphite having the following properties: (1) an x-ray density of at least 2.20 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counter electrode. 10 figs.
Hydrostatic compaction of Microtherm HT.
Broome, Scott Thomas; Bauer, Stephen J.
2010-09-01
Two samples of jacketed Microtherm{reg_sign}HT were hydrostatically pressurized to maximum pressures of 29,000 psi to evaluate both pressure-volume response and change in bulk modulus as a function of density. During testing, each of the two samples exhibited large irreversible compactive volumetric strains with only small increases in pressure; however at volumetric strains of approximately 50%, the Microtherm{reg_sign}HT stiffened noticeably at ever increasing rates. At the maximum pressure of 29,000 psi, the volumetric strains for both samples were approximately 70%. Bulk modulus, as determined from hydrostatic unload/reload loops, increased by more than two-orders of magnitude (from about 4500 psi to over 500,000 psi) from an initial material density of {approx}0.3 g/cc to a final density of {approx}1.1 g/cc. An empirical fit to the density vs. bulk modulus data is K = 492769{rho}{sup 4.6548}, where K is the bulk modulus in psi, and {rho} is the material density in g/cm{sup 3}. The porosity decreased from 88% to {approx}20% indicating that much higher pressures would be required to compact the material fully.
Durham, W.B.; McKinnon, W.B.; Stern, L.A.
2005-01-01
Hydrostatic compaction of granulated water ice was measured in laboratory experiments at temperatures 77 K to 120 K. We performed step-wise hydrostatic pressurization tests on 5 samples to maximum pressures P of 150 MPa, using relatively tight (0.18-0.25 mm) and broad (0.25-2.0 mm) starting grain-size distributions. Compaction change of volume is highly nonlinear in P, typical for brittle, granular materials. No time-dependent creep occurred on the lab time scale. Significant residual porosity (???0.10) remains even at highest P. Examination by scanning electron microscopy (SEM) reveals a random configuration of fractures and broad distribution of grain sizes, again consistent with brittle behavior. Residual porosity appears as smaller, well-supported micropores between ice fragments. Over the interior pressures found in smaller midsize icy satellites and Kuiper Belt objects (KBOs), substantial porosity can be sustained over solar system history in the absence of significant heating and resultant sintering. Copyright 2005 by the American Geophysical Union.
Compact Microscope Imaging System Developed
NASA Technical Reports Server (NTRS)
McDowell, Mark
2001-01-01
The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. The CMIS can be used in situ with a minimum amount of user intervention. This system, which was developed at the NASA Glenn Research Center, can scan, find areas of interest, focus, and acquire images automatically. Large numbers of multiple cell experiments require microscopy for in situ observations; this is only feasible with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control capabilities. The software also has a user-friendly interface that can be used independently of the hardware for post-experiment analysis. CMIS has potential commercial uses in the automated online inspection of precision parts, medical imaging, security industry (examination of currency in automated teller machines and fingerprint identification in secure entry locks), environmental industry (automated examination of soil/water samples), biomedical field (automated blood/cell analysis), and microscopy community. CMIS will improve research in several ways: It will expand the capabilities of MSD experiments utilizing microscope technology. It may be used in lunar and Martian experiments (Rover Robot). Because of its reduced size, it will enable experiments that were not feasible previously. It may be incorporated into existing shuttle orbiter and space station experiments, including glove-box-sized experiments as well as ground-based experiments.
Combined method of compaction of collapsible soils
Bagdasarov, Yu.A.
1994-07-01
The writer proposes a combined method of compaction of collapsible soils. He presents results of investigations carried out to study compacted zones of pads punched (tamped-out) by rammers 10 and 20 tons in mass, as well as a comparative analysis of the pads over against compacted zones obtained by means of plane rammers. The analysis results are illustrated by the {open_quotes}arch effect{close_quotes} on the stress conditions of the soaked soil mass.
Method for preparing porous metal hydride compacts
Ron, M.; Gruen, D.M.; Mendelsohn, M.H.; Sheft, I.
1980-01-21
A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.
Non-compact WZW conformal field theories
Krzysztof Gawedzki
1991-01-01
Non-compact WZW sigma models are considered, especially the ones with symmetric space H(sup C)\\/H as the target, for H in a compact Lie group. The author offers examples of non-rational conformal field theories. The author notes their relation to the compact WZW models, but stresses their distinctive features such as the continuous spectrum of conformal weights, diverging partition functions, and
Method for preparing porous metal hydride compacts
Ron, Moshe (Haifa, IL); Gruen, Dieter M. (Downers Grove, IL); Mendelsohn, Marshall H. (Woodridge, IL); Sheft, Irving (Oak Park, IL)
1981-01-01
A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.
Compaction of asphalt pavement. Final report
Hughes, C.S.
1989-10-01
This synthesis will be of interest to construction and materials engineers, paving contractors, equipment manufacturers, and others who are involved in assessing the performance of asphalt pavements. Information is presented on various issues related to compaction of asphalt pavements. Compaction is one of the most important factors affecting the performance of asphalt pavements. The report of the Transportation Research Board describes the theory, methods, equipment, and specifications related to the compaction of asphalt pavements. A brief history of, the importance of, and factors affecting compaction are also discussed. Construction influences, density measurements, and trends are also considered.
Compact Solid State Cooling Systems: Compact MEMS Electrocaloric Module
2010-10-01
BEETIT Project: UCLA is developing a novel solid-state cooling technology to translate a recent scientific discovery of the so-called giant electrocaloric effect into commercially viable compact cooling systems. Traditional air conditioners use noisy, vapor compression systems that include a polluting liquid refrigerant to circulate within the air conditioner, absorb heat, and pump the heat out into the environment. Electrocaloric materials achieve the same result by heating up when placed within an electric field and cooling down when removed—effectively pumping heat out from a cooler to warmer environment. This electrocaloric-based solid state cooling system is quiet and does not use liquid refrigerants. The innovation includes developing nano-structured materials and reliable interfaces for heat exchange. With these innovations and advances in micro/nano-scale manufacturing technologies pioneered by semiconductor companies, UCLA is aiming to extend the performance/reliability of the cooling module.
Ball, Don G. (Livermore, CA)
1992-01-01
A charge regulation circuit provides regulation of an unregulated voltage supply in the range of 0.01%. The charge regulation circuit is utilized in a preferred embodiment in providing regulated voltage for controlling the operation of a laser.
Explosive compaction of spent shale - void-volume generation for retort development
Young, C.; Trent, B.C.; Harak, A.E.; Bartke, T.C.
1984-08-01
The explosive compaction of spent shale provides a potential means by which the void volume in previously burned in situ retorts can be recovered and transferred to adjacent newly created retort modules. The technical and economic feasibility of an oil shale processing operation based on the compaction of spent shale will depend directly on the explosive energies required to compact the spent shale, fragment and introduce a uniformly distributed void volume into the fresh shale and the coupling characteristics between these two processes if carried out simultaneously. Static and dynamic laboratory experiments on spent shale compaction have been combined with one- and two-dimensional finite-difference calculations to evaluate the coupling between the compaction and fragmentation processes and the effects of retort geometry and shothole charge timing. The numerical analyses show that the additional explosive energy required to effect a desired degree of spent shale compaction is less than that required for the fragmentation of shale when blasted into a mined out void volume and that the processes of compaction and fragmentation can be coupled such that the overall explosive requirements are not excessively large. The development of a 9.8 m by 9.8 m square (in cross-section) retort in direct juxtaposition to a burned retort (of 108 ml/kg or 26 gpt oil shale and with 22% initial fracture void volume) required explosive energies of 12.91 Joules per gm of fresh shale processed (approximately 6.9 lbs of explosive per ton). These explosive energies would be acceptable to a commercial operation and field tests are now required to further evaluate the spent shale compaction concept. 15 refs., 19 figs., 1 tab.
Optimization of coal blends for coke making by the stamp-charging process
Kuyumcu, H.Z. [Saarberg-Interplan GmbH, Saarbruecken (Germany)
1994-12-31
Stamp charging means coke production in horizontal chamber ovens, where the coal blend is previously compacted to a so-called coal cake with slightly smaller dimensions than those of the oven and charged to the oven from the battery ram side through the oven door. Due to the high density of the coal charge achieved by stamp charging, this technology allows a high flexibility in the range of charge materials. Stamp-charging technology allows the use of high-volatile, low-caking, and inexpensive charge materials to produce blast furnace coke with good mechanical properties at reasonable prices. Based on the factors of raw materials and technologies, this paper illustrates strategies to optimize blends for coke-making by the stamp-charging process.
2006-06-12
Using fewnomial theory we show that for a given number of charges there ... of µ positive charges with the values ?1,...,?µ, and ? negative charges with the ...... (ii) The absolute value of all ratios ck(¯x)/cl(¯x) in the unique linear dependence.
Spacecraft Charging Technology, 1980
NASA Technical Reports Server (NTRS)
1981-01-01
The third Spacecraft Charging Technology Conference proceedings contain 66 papers on the geosynchronous plasma environment, spacecraft modeling, charged particle environment interactions with spacecraft, spacecraft materials characterization, and satellite design and testing. The proceedings is a compilation of the state of the art of spacecraft charging and environmental interaction phenomena.
NSDL National Science Digital Library
William C. Robertson, Ph.D.
2005-01-01
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.
Jeanjean, Louis
Degenerate Parabolic Pbs + FV Approximation Towards time compactness Functional Analysis Methods L1 Franche-Comté Besançon, France FVCA 6 Prague, Czech Republic, June 2011 #12;Degenerate Parabolic Pbs + FV Direct Estimation of L1 Time Translates 5 Compactness by monotonicity #12;Degenerate Parabolic Pbs + FV
78 FR 61384 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact
Federal Register 2010, 2011, 2012, 2013, 2014
2013-10-03
...notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr. Gary S. Barron...may be addressed to Mr. Gary S. Barron, FBI Compact Officer, Module D3, 1000 Custer...September 25, 2013. Gary S. Barron, FBI Compact Officer, Criminal Justice...
77 FR 20051 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact
Federal Register 2010, 2011, 2012, 2013, 2014
2012-04-03
...notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr. Gary S. Barron...may be addressed to Mr. Gary S. Barron, FBI Compact Officer, Module D3, 1000 Custer...Dated: March 27, 2012. Gary S. Barron, FBI Compact Officer, Criminal Justice...
75 FR 62568 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact
Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-12
...the Council should notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr. Gary S. Barron at (304) 625-2803...CONTACT: Inquiries may be addressed to Mr. Gary S. Barron, FBI Compact Officer, Compact Council Office, Module D3, 1000...
78 FR 20355 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact
Federal Register 2010, 2011, 2012, 2013, 2014
2013-04-04
...notify the Federal Bureau of Investigation (FBI) Compact Officer, Mr. Gary S. Barron...may be addressed to Mr. Gary S. Barron, FBI Compact Officer, Module D3, 1000 Custer...Dated: March 26, 2013. Gary S. Barron, FBI Compact Officer, Criminal Justice...
76 FR 66326 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact
Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-26
...the Council should notify the Federal Bureau Of Investigation (FBI) Compact Officer, Mr. Gary S. Barron at (304) 625-2803...CONTACT: Inquiries may be addressed to Mr. Gary S. Barron, FBI Compact Officer, Compact Council Office, Module D3, 1000...
Post-compaction heat-treatment response of dynamically-compacted Inconel 718 powder
M. A. Morris; E. Sauvain; D. G. Morris
1987-01-01
Dynamically-compacted Inconel 718 powder has been heat treated in order to examine the evolution of microstructural recovery and hardness, recrystallization and grain coarsening, and interparticle-adhesion and fracture response. Following dynamic compaction the compacted powders are imperfectly bonded and the material is fairly brittle; the shock wave has caused significant hardening; local microstructures and properties are variable from particle surface to
Pasta structures in compact stars
Toshiki Maruyama; Toshitaka Tatsumi; Tomoki Endo; Satoshi Chiba
2006-05-31
We review our recent works about ``pasta'' structures following the first-order phase transition in dense matter, which correspond to the structured mixed phases with geometrical symmetries. Three kinds of phase transitions at different density ranges are examined as the stages of pasta structures: liquid-gas phase transition at subnuclear density, kaon condensation and hadron-quark phase transition at high density. Charge density as well as particle density is non-uniform there. A consistent treatment of the Coulomb potential and the particle densities is presented and a peculiar role of the Coulomb potential is elucidated: the physical picture of the Maxwell construction will be effectively recovered. It largely influences the density regime of pasta structures by the charge screening effect.
Development of Cs 2Te photocathode rf gun system for compact THz SASE-FEL
NASA Astrophysics Data System (ADS)
Kuroda, R.; Ogawa, H.; Sei, N.; Toyokawa, H.; Yagi-Watanabe, K.; Yasumoto, M.; Koike, M.; Yamada, K.; Yanagida, T.; Nakajyo, T.; Sakai, F.
2008-08-01
A compact terahertz (THz) SASE-FEL source has been developed with a compact S-band electron linac at AIST. The S-band linac has been improved using a Cs 2Te photocathode rf gun with a compact load-lock system. The 40 MeV electron beam which has a bunch charge of more than 2 nC/bunch was stably generated using our system with the Cs 2Te photocathode, and the quantum efficiency (QE) typically achieved was about 0.3%. The surface observation of the Cs 2Te photocathode to obtain the surface micrographs and QE mapping images was successfully performed with a photoelectron emission microscopy (PEEM).
Experimental studies of compact toroids
Not Available
1991-01-01
The Berkeley Compact Toroid Experiment (BCTX) device is a plasma device with a Marshall-gun generated, low aspect ratio toroidal plasma. The device is capable of producing spheromak-type discharges and may, with some modification, produce low-aspect ratio tokamak configurations. A unique aspect of this experimenal devie is its large lower hybrid (LH) heating system, which consists of two 450MHz klystron tubes generating 20 megawatts each into a brambilla-type launching structure. Successful operation with one klystron at virtually full power (18 MW) has been accomplished with 110 {mu}s pulse length. A second klystron is currently installed in its socket and magnet but has not been added to the RF drive system. This report describes current activities and accomplishments and describes the anticipated results of next year's activity.
Compact Microwave Fourier Spectrum Analyzer
NASA Technical Reports Server (NTRS)
Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry
2009-01-01
A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.
Compact Sources of Ultrashort Pulses
NASA Astrophysics Data System (ADS)
Duling, Irl N., III
2006-11-01
List of contributors; Acronyms and abbreviations; Preface; 1. Short pulse generation H. A. Haus; 2. Passive modelocking in solid state lasers Thomas Brabec, Stephen M. J. Kelly and Ferenc Krausz; 3. Compact modelocked solid state lasers pumped by laser diodes John R. M. Barr; 4. Modelocking of all-fiber lasers Irl N. Duling, III and Michael L. Dennis; 5. Nonlinear polarization evolution in passively modelocked fiber lasers Martin E. Fermann; 6. Ultrafast vertical cavity semiconductor lasers Wenbin Jiang and John Bowers; 7. High power ultrafast semiconductor for injection diode lasers Peter J. Delfyett; 8. The hybrid soliton pulse source Paul A. Morton; 9. Monolithic colliding pulse modelocked diode lasers Ming C. Wu and Young-Kai Chen; Index.
A Compact Wakefield Measurement Facility
NASA Astrophysics Data System (ADS)
Power, J. G.; Gai, W.
2015-10-01
The conceptual design of a compact, photoinjector-based, facility for high precision measurements of wakefields is presented. This work is motivated by the need for a thorough understanding of beam induced wakefield effects for any future linear collider. We propose to use a high brightness photoinjector to generate (approximately) a 2 nC, 2 mm-mrad drive beam at 20 MeV to excite wakefields and a second photoinjector to generate a 5 MeV, variably delayed, trailing witness beam to probe both the longitudinal and transverse wakefields in the structure under test. Initial estimates show that we can detect a minimum measurable dipole transverse wake function of 0.1 V/pC/m/mm and a minimum measurable monopole longitudinal wake function of 2.5 V/pC/m. Simulations results for the high brightness photoinjector, calculations of the facility's wakefield measurement resolution, and the facility layout are presented.
Anisotropic models for compact stars
NASA Astrophysics Data System (ADS)
Maurya, S. K.; Gupta, Y. K.; Ray, Saibal; Dayanandan, Baiju
2015-05-01
In the present paper we obtain an anisotropic analog of the Durgapal and Fuloria (Gen Relativ Gravit 17:671, 1985) perfect fluid solution. The methodology consists of contraction of the anisotropic factor with the help of both metric potentials and . Here we consider the same as Durgapal and Fuloria (Gen Relativ Gravit 17:671, 1985) did, whereas is as given by Lake (Phys Rev D 67:104015, 2003). The field equations are solved by the change of dependent variable method. The solutions set mathematically thus obtained are compared with the physical properties of some of the compact stars, strange star as well as white dwarf. It is observed that all the expected physical features are available related to the stellar fluid distribution, which clearly indicates the validity of the model.
Compact torus experiments and theory
Armstrong, W.T.; Barnes, D.C.; Bartsch, R.R.
1980-01-01
Two types of compact toroids have been studied: spheromaks and field-reversed configurations (FRC). Spheromaks, which contain both toroidal and poloidal fields, have been formed with a magnetized coaxial injector and trapped in both prolate and oblate flux conservers. As expected from theory, the prolate configuration always tilts, but the oblate configuration can be made stable even in the presence of a guide field. Observations include 150..mu..s lifetimes,
THE MOST DISTANT COMPACT GROUPS
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
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.
General Relativity&Compact Stars
Glendenning, Norman K.
2005-08-16
Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.
Ductile compaction in volcanic conduits
NASA Astrophysics Data System (ADS)
Wadsworth, Fabian; Vasseur, Jeremie; Lavallée, Yan; Scheu, Bettina; Dingwell, Donald
2014-05-01
Silicic magmas typically outgas through connected pore and crack networks with a high gas permeability without the need for decoupled movement of pores in the melt. It is the efficiency with which this process can occur which governs the pressure in the pore network. However, such a connected coupled network is generally mechanically unstable and will relax until volume equilibrium when the pores become smaller and isolated. Consequently, gas permeability can be reduced during densification. Cycles of outgassing events recorded in gas monitoring data show that permeable flow of volatiles is often transient, which is interpreted to reflect magma densification and the closing of pore-networks. Understanding the timescale over which this densification process occurs is critical to refining conduit models that seek to predict the pressure evolution in a pore-network leading to eruptions. We conduct uniaxial compaction experiments to parameterize non-linear creep and relaxation processes that occur in magmas with total pore fractions 0.2-0.85. We analyze our results by applying both viscous sintering and viscoelastic deformation theory to test the applicability of currently accepted models to flow dynamics in the uppermost conduit involving highly porous magmas. We show that purely ductile compaction can occur rapidly and that pore networks can close over timescales analogous to the inter-eruptive periods observed during classic cyclic eruptions such as those at Soufriere Hills volcano, Montserrat, in 1997. At upper-conduit axial stresses (0.1-5 MPa) and magmatic temperatures (830-900 oC), we show that magmas can evolve to porosities analogous to dome lavas erupted at the same volcano. Such dramatic densification events over relatively short timescales and in the absence of brittle deformation show that permeable flow will be inhibited at upper conduit levels. We therefore propose that outgassing is a key feature at many silicic volcanoes and should be incorporated into conduit flow models.
Physics of Compact Advanced Stellarators
M.C. Zarnstorff; L.A. Berry; A. Brooks; E. Fredrickson; G.-Y. Fu; S. Hirshman; S. Hudson; L.-P. Ku; E. Lazarus; D. Mikkelsen; D. Monticello; G.H. Neilson; N. Pomphrey; A. Reiman; D. Spong; D. Strickler; A. Boozer; W.A. Cooper; R. Goldston; R. Hatcher; M. Isaev; C. Kessel; J. Lewandowski; J. Lyon; P. Merkel; H. Mynick; B.E. Nelson; C. Nuehrenberg; M. Redi; W. Reiersen; P. Rutherford; R. Sanchez; J. Schmidt; R.B. White
2001-08-14
Compact optimized stellarators offer novel solutions for confining high-beta plasmas and developing magnetic confinement fusion. The 3-D plasma shape can be designed to enhance the MHD stability without feedback or nearby conducting structures and provide drift-orbit confinement similar to tokamaks. These configurations offer the possibility of combining the steady-state low-recirculating power, external control, and disruption resilience of previous stellarators with the low-aspect ratio, high beta-limit, and good confinement of advanced tokamaks. Quasi-axisymmetric equilibria have been developed for the proposed National Compact Stellarator Experiment (NCSX) with average aspect ratio 4-4.4 and average elongation of approximately 1.8. Even with bootstrap-current consistent profiles, they are passively stable to the ballooning, kink, vertical, Mercier, and neoclassical-tearing modes for beta > 4%, without the need for external feedback or conducting walls. The bootstrap current generates only 1/4 of the magnetic rotational transform at beta = 4% (the rest is from the coils), thus the equilibrium is much less nonlinear and is more controllable than similar advanced tokamaks. The enhanced stability is a result of ''reversed'' global shear, the spatial distribution of local shear, and the large fraction of externally generated transform. Transport simulations show adequate fast-ion confinement and thermal neoclassical transport similar to equivalent tokamaks. Modular coils have been designed which reproduce the physics properties, provide good flux surfaces, and allow flexible variation of the plasma shape to control the predicted MHD stability and transport properties.
Cooling of Color Superconducting Compact Stars
David Blaschke
2006-03-26
We review the status of research on the cooling of compact stars, with emphasis on the influence of color superconducting quark matter phases. Although a consistent microscopic approach is not yet available, severe constraints on the phase structure of matter at high densities come from recent mass and cooling observations of compact stars.
The Compressor: Concurrent, Incremental, and Parallel Compaction
Petrank, Erez
The Compressor: Concurrent, Incremental, and Parallel Compaction Haim Kermany Erez Petrank Dept non-intrusive compactor is still missing. In this paper we present the Compressor, a novel compaction, thereby allowing acceptable runs on large heaps. Furthermore, the Compressor is the first compactor
Construction of compactly supported biorthogonal wavelets: I
Shen, Zuowei
Construction of compactly supported biorthogonal wavelets: I Sherman D. Riemenschneider Zuowei Shen://approx.math.ualberta.ca/~sherm http://www.math.nus.sg/~matzuows Abstract: This paper presents a construction of compactly supported dual functions of a given box spline in L2(IRs). In particular, a concrete method for the construction
Physics of compact ignition tokamak designs
Singer, C.E.; Ku, L.P.; Bateman, G.; Seidl, F.; Sugihara, M.
1986-03-01
Models for predicting plasma performance in compact ignition experiments are constructed on the basis of theoretical and empirical constraints and data from tokamak experiments. Emphasis is placed on finding transport and confinement models which reproduce results of both ohmically and auxiliary heated tokamak data. Illustrations of the application of the models to compact ignition designs are given.
An Obstruction to Quantizing Compact Symplectic Manifolds
Mark J. Gotay; Janusz Grabowski; Hendrik B. Grundling
1999-10-21
We prove that there are no nontrivial finite-dimensional Lie representations of certain Poisson algebras of polynomials on a compact symplectic manifold. This result is used to establish the existence of a universal obstruction to quantizing a compact symplectic manifold, regardless of the dimensionality of the representation.
PICOBIT: A Compact Scheme System for Microcontrollers
Tobin-Hochstadt, Sam
, small microcontroller based embedded systems have traditionally been implemented using low- levelPICOBIT: A Compact Scheme System for Microcontrollers Vincent St-Amour and Marc Feeley Universit for memory constrained embedded systems. To achieve a compact system we have tackled the space issue in three
Exploration of Compact Stellarators as Power Plants
California at San Diego, University of
Exploration of Compact Stellarators as Power Plants: Initial Results from ARIES-CS Study Farrokh, see: http://aries.ucsd.edu/ #12;Exploration and Optimization of Compact Stellarators as Power Plants in the context of power plant studies, e.g., particle loss Divertor (location, particle and energy distribution
Compact Process Development at Babcock & Wilcox
Eric Shaber; Jeffrey Phillips
2012-03-01
Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of compaction trials have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel at packing fractions exceeding 46% by volume. Results from these trials are included. The scale-up effort is nearing completion with the process installed and operable using nuclear fuel materials. Final process testing is in progress to certify the process for manufacture of qualification test fuel compacts in 2012.
Compact Between Resident Physicians and Their Teachers
Emmons, Scott
Compact Between Resident Physicians and Their Teachers January 2006 www.aamc.org/residentcompact #12;The Compact Between Resident Physicians and Their Teachers is a declaration of the fundamental, Asthma and Immunology American Academy of Dermatology American Academy of Family Physicians American
Chen, Y -; Caporaso, G J; Guethlein, G; Sampayan, S; Akana, G; Anaya, R; Blackfield, D; Cook, E; Falabella, S; Gower, E; Harris, J; Hawkins, S; Hickman, B; Holmes, C; Horner, A; Nelson, S; Paul, A; Pearson, D; Poole, B; Richardson, R; Sanders, D; Stanley, J; Sullivan, J; Wang, L; Watson, J; Weir, J
2009-06-17
Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory. The DWA accelerator uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. Its high electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The DWA concept can be applied to accelerate charge particle beams with any charge to mass ratio and energy. Based on the DWA system, a novel compact proton therapy accelerator is being developed. This proton therapy system will produce individual pulses that can be varied in intensity, energy and spot width. The system will be capable of being sited in a conventional linac vault and provide intensity modulated rotational therapy. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, SiC photoconductive switches and compact proton sources. Applications of the DWA accelerator to problems in homeland security will also be discussed.
Secondary Structures in Long Compact Polymers
Richard Oberdorf; Allison Ferguson; Jesper L. Jacobsen; Jane' Kondev
2005-08-03
Compact polymers are self-avoiding random walks which visit every site on a lattice. This polymer model is used widely for studying statistical problems inspired by protein folding. One difficulty with using compact polymers to perform numerical calculations is generating a sufficiently large number of randomly sampled configurations. We present a Monte-Carlo algorithm which uniformly samples compact polymer configurations in an efficient manner allowing investigations of chains much longer than previously studied. Chain configurations generated by the algorithm are used to compute statistics of secondary structures in compact polymers. We determine the fraction of monomers participating in secondary structures, and show that it is self averaging in the long chain limit and strictly less than one. Comparison with results for lattice models of open polymer chains shows that compact chains are significantly more likely to form secondary structure.
Compact stars made of fermionic dark matter
Narain, Gaurav [Indian Institute of Technology, Kanpur, Uttar Pradesh (India); Institut fuer Theoretische Physik, J. W. Goethe Universitaet, Max von Laue-Strasse 1, D-60438 Frankfurt (Germany); Schaffner-Bielich, Juergen [Institut fuer Theoretische Physik, J. W. Goethe Universitaet, Max von Laue-Strasse 1, D-60438 Frankfurt (Germany); Mishustin, Igor N. [Frankfurt Institute for Advanced Studies, J. W. Goethe Universitaet, Max von Laue-Strasse 1, D-60438 Frankfurt (Germany); The Kurchatov Institute, Russian Research Center, 123182 Moscow (Russian Federation)
2006-09-15
Compact stars consisting of fermions with arbitrary masses and interaction strengths are studied by solving the structure equation of general relativity, the Tolman-Oppenheimer-Volkoff equations. Scaling solutions are derived for a free and an interacting Fermi gas and tested by numerical calculations. We demonstrate that there is a unique mass-radius relation for compact stars made of free fermions which is independent of the fermion mass. For sufficiently strong interactions, the maximum stable mass of compact stars and its radius are controlled by the parameter of the interaction, both increasing linearly with the interaction strength. The mass-radius relation for compact stars made of strongly interacting fermions shows that the radius remains approximately constant for a wide range of compact star masses.
Electric Charge Electric charge is a fundamental property
Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University
Electric Charge Â· Electric charge is a fundamental property of atomic particles Â such as electrons object has equal amounts of each type of charge so no net charge Â· Object is said to be electrically charge contained in an object Â· The net charge of an isolated system remains constant #12;Law of Electric
The EBIT charge breeder at NSCL
NASA Astrophysics Data System (ADS)
Lapierre, Alain; Schwarz, Stefan; Kittimanapun, Kritsada; Bollen, Georg; Kester, Oliver
2011-10-01
The National Superconducting Cyclotron Laboratory (NSCL) is finalizing ReA to reaccelerate rare-isotope beams to energies of ~0.3-20 MeV/u. ReA consists of an electron-beam ion source / trap (EBIS/T), a mass separator, a radio-frequency quadrupole (RFQ) pre-accelerator, and a superconducting radio-frequency linear accelerator (SRF-LINAC). By increasing the charge of ions injected into the RFQ and SRF-LINAC, this charge breeder is a key component to provide a compact and cost-efficient reaccelerator. The ReA EBIT has started producing highly charged ion beams. It is equipped with an electron gun yielding a few amperes and a magnet configuration made of Helmholtz coils and a solenoid, providing a maximum magnetic field strength of 6 T. The solenoid magnet configuration will guarantee high beam acceptance. The combination of a high-current gun and strong magnetic field will allow this EBIS/T to reach high electron current densities suitable to rapidly increase the charge of short-lived isotopes within tens of milliseconds. The status of the EBIT will be presented.
A compact bipolar pulse-forming network-Marx generator based on pulse transformers.
Zhang, Huibo; Yang, Jianhua; Lin, Jiajin; Yang, Xiao
2013-11-01
A compact bipolar pulse-forming network (PFN)-Marx generator based on pulse transformers is presented in this paper. The high-voltage generator consisted of two sets of pulse transformers, 6 stages of PFNs with ceramic capacitors, a switch unit, and a matched load. The design is characterized by the bipolar pulse charging scheme and the compact structure of the PFN-Marx. The scheme of bipolar charging by pulse transformers increased the withstand voltage of the ceramic capacitors in the PFNs and decreased the number of the gas gap switches. The compact structure of the PFN-Marx was aimed at reducing the parasitic inductance in the generator. When the charging voltage on the PFNs was 35 kV, the matched resistive load of 48 ? could deliver a high-voltage pulse with an amplitude of 100 kV. The full width at half maximum of the load pulse was 173 ns, and its rise time was less than 15 ns. PMID:24289423
Relativistic structure, stability, and gravitational collapse of charged neutron stars
Ghezzi, Cristian R. [Instituto de Matematica, Estatistica e Computacao Cientifica, Universidade Estadual de Campinas, Campinas, Sao Paulo (Brazil)
2005-11-15
Charged stars have the potential of becoming charged black holes or even naked singularities. We present a set of numerical solutions of the Tolman-Oppenheimer-Volkov equations that represents spherical charged compact stars in hydrostatic equilibrium. The stellar models obtained are evolved forward in time integrating the Einstein-Maxwell field equations. We assume an equation of state of a neutron gas at zero temperature. The charge distribution is taken as being proportional to the rest mass density distribution. The set of solutions present an unstable branch, even with charge-to-mass ratios arbitrarily close to the extremum case. We perform a direct check of the stability of the solutions under strong perturbations and for different values of the charge-to-mass ratio. The stars that are in the stable branch oscillate and do not collapse, while models in the unstable branch collapse directly to form black holes. Stars with a charge greater than or equal to the extreme value explode. When a charged star is suddenly discharged, it does not necessarily collapse to form a black hole. A nonlinear effect that gives rise to the formation of a shell of matter (in supermassive stars), is negligible in the present simulations. The results are in agreement with the third law of black hole thermodynamics and with the cosmic censorship conjecture.
Electrodynamics of balanced charges
Babin, Anatoli
2009-01-01
In this work we modify the wave-corpuscle mechanics for elementary charges introduced by us recently. This modification is designed to better describe electromagnetic (EM) phenomena at atomic scales. It includes a modification of the concept of the classical EM field and a new model for the elementary charge which we call a balanced charge (b-charge). A b-charge does not interact with itself electromagnetically, and every b-charge possesses its own elementary EM field. The EM energy is naturally partitioned as the interaction energy between pairs of different b-charges. We construct EM theory of b-charges (BEM) based on a relativistic Lagrangian with the following properties: (i) b-charges interact only through their elementary EM potentials and fields; (ii) the field equations for the elementary EM fields are exactly the Maxwell equations with proper currents; (iii) a free charge moves uniformly preserving up to the Lorentz contraction its shape; (iv) the Newton equations with the Lorentz forces hold approxi...
7 CFR 621.43 - Interstate compacts and commissions.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 2010-01-01 false Interstate compacts and commissions. 621.43 Section...Coordination § 621.43 Interstate compacts and commissions. As assigned...contact for governing bodies of interstate compacts and commissions concerned with the...
NASA Astrophysics Data System (ADS)
McClarty, P. A.; O'Brien, A.; Pollmann, F.
2014-05-01
We consider a classical model of charges ±q on a pyrochlore lattice in the presence of long-range Coulomb interactions. This model first appeared in the early literature on charge order in magnetite [P. W. Anderson, Phys. Rev. 102, 1008 (1956), 10.1103/PhysRev.102.1008]. In the limit where the interactions become short ranged, the model has a ground state with an extensive entropy and dipolar charge-charge correlations. When long-range interactions are introduced, the exact degeneracy is broken. We study the thermodynamics of the model and show the presence of a correlated charge liquid within a temperature window in which the physics is well described as a liquid of screened charged defects. The structure factor in this phase, which has smeared pinch points at the reciprocal lattice points, may be used to detect charge ice experimentally. In addition, the model exhibits fractionally charged excitations ±q/2 which are shown to interact via a 1/r potential. At lower temperatures, the model exhibits a transition to a long-range ordered phase. We are able to treat the Coulombic charge ice model and the dipolar spin ice model on an equal footing by mapping both to a constrained charge model on the diamond lattice. We find that states of the two ice models are related by a staggering field which is reflected in the energetics of these two models. From this perspective, we can understand the origin of the spin ice and charge ice ground states as coming from a dipolar model on a diamond lattice. We study the properties of charge ice in an external electric field, finding that the correlated liquid is robust to the presence of a field in contrast to the case of spin ice in a magnetic field. Finally, we comment on the transport properties of Coulombic charge ice in the correlated liquid phase.
Solvation Effects on Structure and Charge Distribution in Anionic Clusters
NASA Astrophysics Data System (ADS)
Weber, J. Mathias
2015-03-01
The interaction of ions with solvent molecules modifies the properties of both solvent and solute. Solvation generally stabilizes compact charge distributions compared to more diffuse ones. In the most extreme cases, solvation will alter the very composition of the ion itself. We use infrared photodissociation spectroscopy of mass-selected ions to probe how solvation affects the structures and charge distributions of metal-CO2 cluster anions. We gratefully acknowledge the National Science Foundation for funding through Grant CHE-0845618 (for graduate student support) and for instrumentation funding through Grant PHY-1125844.
Design and Build a Compact Raman Sensor for Identification of Chemical Composition
NASA Technical Reports Server (NTRS)
Garcia, Christopher S.; Abedin, M. Nurul; Ismail, Syed; Sharma, Shiv K.; Misra, Anupam K.; Sandford, Stephen P.; Elsayed-Ali, Hani
2008-01-01
A compact remote Raman sensor system was developed at NASA Langley Research Center. This sensor is an improvement over the previously reported system, which consisted of a 532 nm pulsed laser, a 4-inch telescope, a spectrograph, and an intensified charge-coupled devices (CCD) camera. One of the attractive features of the previous system was its portability, thereby making it suitable for applications such as planetary surface explorations, homeland security and defense applications where a compact portable instrument is important. The new system was made more compact by replacing bulky components with smaller and lighter components. The new compact system uses a smaller spectrograph measuring 9 x 4 x 4 in. and a smaller intensified CCD camera measuring 5 in. long and 2 in. in diameter. The previous system was used to obtain the Raman spectra of several materials that are important to defense and security applications. Furthermore, the new compact Raman sensor system is used to obtain the Raman spectra of a diverse set of materials to demonstrate the sensor system's potential use in the identification of unknown materials.
Structure of water at charged interfaces: a molecular dynamics study.
Dewan, Shalaka; Carnevale, Vincenzo; Bankura, Arindam; Eftekhari-Bafrooei, Ali; Fiorin, Giacomo; Klein, Michael L; Borguet, Eric
2014-07-15
The properties of water molecules located close to an interface deviate significantly from those observed in the homogeneous bulk liquid. The length scale over which this structural perturbation persists (the so-called interfacial depth) is the object of extensive investigations. The situation is particularly complicated in the presence of surface charges that can induce long-range orientational ordering of water molecules, which in turn dictate diverse processes, such as mineral dissolution, heterogeneous catalysis, and membrane chemistry. To characterize the fundamental properties of interfacial water, we performed molecular dynamics (MD) simulations on alkali chloride solutions in the presence of two types of idealized charged surfaces: one with the charge density localized at discrete sites and the other with a homogeneously distributed charge density. We find that, in addition to a diffuse region where water orientation shows no layering, the interface region consists of a "compact layer" of solvent next to the surface that is not described in classical electric double layer theories. The depth of the diffuse solvent layer is sensitive to the type of charge distributions on the surface and the ionic strength. Simulations of the aqueous interface of a realistic model of negatively charged amorphous silica show that the water orientation and the distribution of ions strongly depend on the identity of the cations (Na(+) vs Cs(+)) and are not well represented by a simplistic homogeneous charge distribution model. While the compact layer shows different solvent net orientation and depth for Na(+) vs Cs(+), the depth (~1 nm) of the diffuse layer of oriented waters is independent of the identity of the cation screening the charge. The details of interfacial water orientation revealed here go beyond the traditionally used double and triple layer models and provide a microscopic picture of the aqueous/mineral interface that complements recent surface specific experimental studies. PMID:24979659
Compacting Plastic-Bonded Explosive Molding Powders to Dense Solids
B. Olinger
2005-04-15
Dense solid high explosives are made by compacting plastic-bonded explosive molding powders with high pressures and temperatures for extended periods of time. The density is influenced by manufacturing processes of the powders, compaction temperature, the magnitude of compaction pressure, pressure duration, and number of repeated applications of pressure. The internal density variation of compacted explosives depends on method of compaction and the material being compacted.
Laplace spectra on open and compact Zeeman manifolds
Zoltan I. Szabo
2006-02-21
By a recent observation, the Laplacians on the Riemannian manifolds the author used for isospectrality constructions are nothing but the Zeeman-Hamilton operators of free charged particles. These manifolds can be considered as prototypes of the so called Zeeman manifolds. This observation allows to develop a spectral theory both on open Z-manifolds and their compact submanifolds. The theory on open manifolds leads to a new nonperturbative approach to the infinities of QED. This idea exploits that the quantum Hilbert space decomposes into subspaces (Zeeman zones) which are invariant under the actions both of this Zeeman-Laplace operator and the natural complex Heisenberg group representation. Thus a well defined particle theory and zonal geometry can be developed on each zone separately. The most surprising result is that quantities divergent on the global setting are finite on the zonal setting. Even the zonal Feynman integral is well defined. The results include explicit computations of objects such as the zonal spectra, the waves defining the zonal point-spreads, the zonal Wiener-Kac resp. Dirac-Feynman flows, and the corresponding partition functions. The observation adds new view-point also to the problem of finding intertwining operators by which isospectral pairs of metrics with different local geometries on compact submanifolds can be constructed. Among the examples the author constructed the most surprising are the isospectrality families containing both homogeneous and locally inhomogeneous metrics. The observation provides even quantum physical interpretation to the isospectrality.
Compact pulsed electron beam system for microwave generation
NASA Astrophysics Data System (ADS)
Sharma, S. K.; Deb, P.; Shukla, R.; Banerjee, P.; Prabaharan, T.; Adhikary, B.; Verma, R.; Sharma, A.; Shyam, A.
2012-11-01
A compact 180 kV electron beam system is designed for high power microwave generation. The electron beam system is consists of a secondary energy storage device, which can deliver energy to the load at faster rate than usual primary energy storage system such as tesla transformers or marx generator. The short duration, high voltage pulse with fast rise time and good flattop is applied to vacuum diode for high power microwave generation. The compact electron beam system is made up of single turn primary tesla transformer which charges a helical pulse forming line and transfers its energy to vacuum diode through a high voltage pressurized spark gap switch. We have used helical pulse forming line which has higher inductance as compared to coaxial pulse forming line, which in turns increases, the pulse width and reduce the length of the pulse forming line. Water dielectric medium is used because of its high dielectric constant, high dielectric strength and efficient energy storage capability. The time dependent breakdown property and high relative permittivity of water makes it an ideal choice for this system. The high voltage flat-top pulse of 90 kV, 260 ns is measured across the matched load. In this article we have reported the design details, simulation and initial experimental results of 180 kV pulsed electron beam system for high power microwave generation.
Field performance of compacted clay liners
Benson, C.H.; Daniel, D.E.; Boutwell, G.P.
1999-05-01
A database consisting of 85 full-scale compacted clay liners was assembled to evaluate field hydraulic conductivity K{sub F}. Large-scale field hydraulic conductivity tests were conducted on each liner. All of the clay liners were intended to achieve K{sub F} {le} 1 {times} 10{sup {minus}7} cm/s, but only 74% succeeded in meeting this objective. The important factors affecting K{sub F} are the soil wetness relative to the line of optimums and the number of lifts or the thickness of the liner. Poor correlation exists between K{sub F} and hydraulic conductivities measured in the laboratory (K{sub L}) on field-compacted samples (especially for liners with K{sub F} > 10{sup {minus}7} cm/s compacted at lower water contents relative to the line of optimums), percent compaction, and index properties representative of composition (e.g., Atterberg limits and particle size fractions). The findings indicate that (1) compacted clay liners having K{sub F} {le} 10{sup {minus}7} cm/s can be constructed with a broad variety of clayey soils; (2) the primary emphasis should be ensuring compaction is primarily wet of the line of optimums; (3) less emphasis should be placed on other traditional measures such as percent compaction, K{sub L}, and index properties; and (4) liners that are thicker or have a greater number of lifts tend to have lower K{sub F}.
Foster Wheeler compact CFB boiler with INTREX
Hyppaenen, T.; Rainio, A. [Foster Wheeler Energia Oy, Karhula (Finland). Karhula R and D Center; Kauppinen, K.V.O. [Foster Wheeler Energy International, Inc., Varkaus (Finland); Stone, J.E. [Foster Wheeler Energy International, Inc., San Diego, CA (United States)
1997-12-31
Foster Wheeler has introduced a new COMPACT Circulating Fluidized Bed (CFB) boiler design based on the rectangular hot solids separator. The Compact design also enables easy implementation of new designs for INTREX fluid bed heat exchangers. These new products result in many benefits which affect the boiler economy and operation. After initial development of the Compact CFB design it has been applied in demonstration and industrial scale units. The performance of Compact CFB has been proved to be equivalent to conventional Foster Wheeler CFB has been proved to be equivalent to conventional Foster Wheeler CFB boilers with high availability. Several new Foster Wheeler Compact boilers are being built or already in operation. Operational experiences from different units will be discussed in this paper. There are currently Compact units with 100--150 MW{sub e} capacity under construction. With the scale-up experience with conventional CFB boilers and proven design approach and scale-up steps, Foster Wheeler will have the ability to provide large Compact CFB boilers up to 400--600 MW{sub e} capacity.
NASA Astrophysics Data System (ADS)
Keszthelyi, Dániel; Dysthe, Dag Kristian; Jamtveit, Bjørn
2014-05-01
The Ekofisk field is the largest petroleum field in the Norwegian North Sea territory where oil is produced from chalk formations. Early stage of oil production caused considerable changes in pore fluid pressure which led to a reservoir compaction. Pore collapse mechanism caused by the dramatic increase of effective stress, which in turn was caused by the pressure reduction by hydrocarbon depletion, was early identified as a principal reason for the reservoir compaction (Sulak et al. 1991). There have been several attempts to model this compaction. They performed with variable success on predicting the Ekofisk subsidence. However, the most of these models are based on empirical relations and do not investigate in detail the phenomena involved in the compaction. In sake of predicting the Ekofisk subsidence while using only independently measurable variables we used a chalk compaction model valid on geological time-scales (Japsen et al. 2011) assuming plastic pore-collapse mechanism at a threshold effective stress level. We identified the phenomena involved in the pore collapse. By putting them in a sequential order we created a simple statistical analytical model. We also investigated the time-dependence of the phenomena involved and by assuming that one of the phenomena is rate-limiting we could make estimations of the compaction rate at smaller length-scales. By carefully investigating the nature of pressure propagation we could upscale our model to reservoir scale. We found that the predicted compaction rates are close enough to the measured rates. We believe that we could further increase accuracy by refining our model. Sulak, R. M., Thomas, L. K., Boade R. R. (1991) 3D reservoir simulation of Ekofisk compaction drive. Journal of Petroleum Technology, 43(10):1272-1278, 1991. Japsen, P., Dysthe, D. K., Hartz, E. H., Stipp, S. L. S., Yarushina, V. M., Jamtveit. (2011) A compaction front in North Sea chalk. Journal of Geophysical Research: Solid Earth (1978-2012), 116(B11)
General Relativity and Compact Objects
Patrick Das Gupta
2015-07-30
Starting with the conceptual foundation of general relativity (GR) - equivalence principle, space-time geometry and special relativity, I train cross hairs on two characteristic predictions of GR - black holes and gravitational waves. These two consequences of GR have played a significant role in relativistic astrophysics, e.g. compact X-ray sources, quasars, blazars, coalescing binary pulsars, etc. With quantum theory wedded to GR, particle production from vacuum becomes a generic feature whenever event horizons are present. In this paper, I shall briefly discuss the fate of a `black hole atom' when Hawking radiation is taken into account. In the context of gravitational waves, I shall focus on the possible consequences of gravitational and electromagnetic radiation from highly magnetized and rapidly spinning white dwarfs. The discovery of RX J0648.0-4418 system - a WD in a binary with mass slightly over 1.2 $ M_{\\odot}$, and rotating with spin period as short as 13.2 s, provides an impetus to revisit the problem of WD spin evolution due to energy loss.
Compact stellarators with modular coils
Garabedian, P. R.
2000-01-01
Compact stellarator designs with modular coils and only two or three field periods are now available; these designs have both good stability and quasiaxial symmetry providing adequate transport for a magnetic fusion reactor. If the bootstrap current assumes theoretically predicted values a three field period configuration is optimal, but if that net current turns out to be lower, a device with two periods and just 12 modular coils might be better. There are also attractive designs with quasihelical symmetry and four or five periods whose properties depend less on the bootstrap current. Good performance requires that there be a satisfactory magnetic well in the vacuum field, which is a property lacking in a stellarator-tokamak hybrid that has been proposed for a proof of principle experiment. In this paper, we present an analysis of stability for these configurations that is based on a mountain pass theorem asserting that, if two solutions of the problem of magnetohydrodynamic equilibrium can be found, then there has to be an unstable solution. We compare results of our theory of equilibrium, stability, and transport with recently announced measurements from the large LHD experiment in Japan. PMID:10899993
General Relativity and Compact Objects
Gupta, Patrick Das
2015-01-01
Starting with the conceptual foundation of general relativity (GR) - equivalence principle, space-time geometry and special relativity, I train cross hairs on two characteristic predictions of GR - black holes and gravitational waves. These two consequences of GR have played a significant role in relativistic astrophysics, e.g. compact X-ray sources, quasars, blazars, coalescing binary pulsars, etc. With quantum theory wedded to GR, particle production from vacuum becomes a generic feature whenever event horizons are present. In this paper, I shall briefly discuss the fate of a `black hole atom' when Hawking radiation is taken into account. In the context of gravitational waves, I shall focus on the possible consequences of gravitational and electromagnetic radiation from highly magnetized and rapidly spinning white dwarfs. The discovery of RX J0648.0-4418 system - a WD in a binary with mass slightly over 1.2 $ M_{\\odot}$, and rotating with spin period as short as 13.2 s, provides an impetus to revisit the pr...
Compact drilling and sample system
NASA Technical Reports Server (NTRS)
Gillis-Smith, Greg R.; Petercsak, Doug
1998-01-01
The Compact Drilling and Sample System (CDSS) was developed to drill into terrestrial, cometary, and asteroid material in a cryogenic, vacuum environment in order to acquire subsurface samples. Although drills were used by the Apollo astronauts some 20 years ago, this drill is a fraction of the mass and power and operates completely autonomously, able to drill, acquire, transport, dock, and release sample containers in science instruments. The CDSS has incorporated into its control system the ability to gather science data about the material being drilled by measuring drilling rate per force applied and torque. This drill will be able to optimize rotation and thrust in order to achieve the highest drilling rate possible in any given sample. The drill can be commanded to drill at a specified force, so that force imparted on the rover or lander is limited. This paper will discuss the cryo dc brush motors, carbide gears, cryogenic lubrication, quick-release interchangeable sampling drill bits, percussion drilling and the control system developed to achieve autonomous, cryogenic, vacuum, lightweight drilling.
General Relativity and Compact Objects
Patrick Das Gupta
2015-09-22
Starting with the conceptual foundation of general relativity (GR) - equivalence principle, space-time geometry and special relativity, I train cross hairs on two characteristic predictions of GR - black holes and gravitational waves. These two consequences of GR have played a significant role in relativistic astrophysics, e.g. compact X-ray sources, GRBs, quasars, blazars, coalescing binary pulsars, etc. With quantum theory wedded to GR, particle production from vacuum becomes a generic feature whenever event horizons are present. In this paper, I shall briefly discuss the fate of a `black hole atom' when Hawking radiation is taken into account. In the context of gravitational waves, I shall focus on the possible consequences of gravitational and electromagnetic radiation from highly magnetized and rapidly spinning white dwarfs. The discovery of RX J0648.0-4418 system - a WD in a binary with mass slightly over 1.2 $ M_{\\odot}$, and rotating with spin period as short as 13.2 s, provides an impetus to revisit the problem of WD spin evolution due to energy loss.
Charge Islands Through Tunneling
NASA Technical Reports Server (NTRS)
Robinson, Daryl C.
2002-01-01
It has been recently reported that the electrical charge in a semiconductive carbon nanotube is not evenly distributed, but rather it is divided into charge "islands." This paper links the aforementioned phenomenon to tunneling and provides further insight into the higher rate of tunneling processes, which makes tunneling devices attractive. This paper also provides a basis for calculating the charge profile over the length of the tube so that nanoscale devices' conductive properties may be fully exploited.
Compact vs. Exponential-Size LP Relaxations
Carr, R.D.; Lancia, G.
2000-09-01
In this paper we introduce by means of examples a new technique for formulating compact (i.e. polynomial-size) LP relaxations in place of exponential-size models requiring separation algorithms. In the same vein as a celebrated theorem by Groetschel, Lovasz and Schrijver, we state the equivalence of compact separation and compact optimization. Among the examples used to illustrate our technique, we introduce a new formulation for the Traveling Salesman Problem, whose relaxation we show equivalent to the subtour elimination relaxation.
Compaction of salt by means of explosives
Giltner, S.G.; Miller, H.
1996-12-01
One of the concerns with locating radioactive waste storage sites in salt deposits is how to permanently seal the underground storage areas once they have reached their storage capacity. The compaction of salt using explosives has been identified as a potential method of producing permanent seals in both entryways and shafts to storage areas. This paper describes the test procedure and results of a preliminary investigation to determine the feasibility of utilizing explosives in the compaction of salt. Three simple tests were carried out to measure the degree to which loose salt could be compacted.
Strategy Guideline: Compact Air Distribution Systems
A. Burdick
2013-06-01
This guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.
PICOBIT: A Compact Scheme System for Microcontrollers
NASA Astrophysics Data System (ADS)
St-Amour, Vincent; Feeley, Marc
Due to their tight memory constraints, small microcontroller based embedded systems have traditionally been implemented using low-level languages. This paper shows that the Scheme programming language can also be used for such applications, with less than 7 kB of total memory. We present PICOBIT, a very compact implementation of Scheme suitable for memory constrained embedded systems. To achieve a compact system we have tackled the space issue in three ways: the design of a Scheme compiler generating compact bytecode, a small virtual machine, and an optimizing C compiler suited to the compilation of the virtual machine.
Ultra-compact (X-ray) binaries
G. Nelemans; P. G. Jonker
2006-05-30
A short review of ultra-compact binaries, focused on ultra-compact X-ray binaries, is followed by a discussion of recent results of our VLT campaign to obtain optical spectra of (candidate) ultra-compact X-ray binaries. We find evidence for carbon/oxygen as well as helium/nitrogen discs and no evidence for (traces) of hydrogen. This suggests that the donors in the observed systems are white dwarfs. However, we also find large differences between the two C/O discs of which we have good spectra, which highlights the need for a better understanding of the optical spectra.
Compaction dynamics in ductile granular media
Lina Uri; Dag Kristian Dysthe; Jens Feder
2005-10-19
Ductile compaction is common in many natural systems, but the temporal evolution of such systems is rarely studied. We observe surprising oscillations in the weight measured at the bottom of a self-compacting ensemble of ductile grains. The oscillations develop during the first ten hours of the experiment, and usually persist through the length of an experiment (one week). The weight oscillations are connected to the grain--wall contacts, and are directly correlated with the observed strain evolution and the dynamics of grain--wall contacts during the compaction. Here, we present the experimental results and characteristic time constants of the system, and discuss possible reasons for the measured weight oscillations.
Charging of interplanetary grains
NASA Technical Reports Server (NTRS)
Baragiola, R. A.; Johnson, R. E.; Newcomb, John L.
1995-01-01
The objective of this program is to quantify, by laboratory experiments, the charging of ices and other insulators subject to irradiation with electrons, ions and ultraviolet photons and to model special conditions based on the data. The system and conditions to be studied are those relevant for charging of dust in magnetospheric plasmas. The measurements are supplemented by computer simulations of charging or grains under a variety of conditions. Our work for this period involved experiments on water ice, improved models of charging of ice grains for Saturn's E-ring, and the construction of apparatus for electron impact studies and measurements of electron energy distributions.
Results of Compact Stellarator engineering trade studies
Bromberg, Leslie
A number of technical requirements and performance criteria can drive stellarator costs, e.g., tight tolerances, accurate coil positioning, low aspect ratio (compactness), choice of assembly strategy, metrology, and ...
Steady state compact toroidal plasma production
Turner, William C. (Livermore, CA)
1986-01-01
Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.
Gravitational waves from merging compact binaries
Hughes, Scott A.
Largely motivated by the development of highly sensitive gravitational-wave detectors, our understanding of merging compact binaries and the gravitational waves they generate has improved dramatically in recent years. ...
Deep Compaction Control of Sandy Soils
NASA Astrophysics Data System (ADS)
Ba?achowski, Lech; Kurek, Norbert
2015-02-01
Vibroflotation, vibratory compaction, micro-blasting or heavy tamping are typical improvement methods for the cohesionless deposits of high thickness. The complex mechanism of deep soil compaction is related to void ratio decrease with grain rearrangements, lateral stress increase, prestressing effect of certain number of load cycles, water pressure dissipation, aging and other effects. Calibration chamber based interpretation of CPTU/DMT can be used to take into account vertical and horizontal stress and void ratio effects. Some examples of interpretation of soundings in pre-treated and compacted sands are given. Some acceptance criteria for compaction control are discussed. The improvement factors are analysed including the normalised approach based on the soil behaviour type index.
ACTIVELY CONTROLLED AFTERBURNER FOR COMPACT WASTE INCINERATION
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...
28 CFR 2.107 - Interstate Compact.
Code of Federal Regulations, 2014 CFR
2014-07-01
...Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT...with regard to the following individuals on parole supervision pursuant to the Interstate Parole and Probation Compact authorized by...
28 CFR 2.107 - Interstate Compact.
Code of Federal Regulations, 2013 CFR
2013-07-01
...Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT...with regard to the following individuals on parole supervision pursuant to the Interstate Parole and Probation Compact authorized by...
28 CFR 2.107 - Interstate Compact.
Code of Federal Regulations, 2012 CFR
2012-07-01
...Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT...with regard to the following individuals on parole supervision pursuant to the Interstate Parole and Probation Compact authorized by...
28 CFR 2.107 - Interstate Compact.
Code of Federal Regulations, 2011 CFR
2011-07-01
...Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT...with regard to the following individuals on parole supervision pursuant to the Interstate Parole and Probation Compact authorized by...
Pharmaceutical tablet compaction : product and process design
Pore, Mridula
2009-01-01
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 ...
Diagnostics for the National Compact Stellarator Experiment
B.C. Stratton; D. Johnson; R. Feder; E. Fredrickson; H. Neilson; H. Takahashi; M. Zarnstorf; M. Cole; P. Goranson; E. Lazarus; B. Nelson
2003-09-16
The status of planning of the National Compact Stellarator Experiment (NCSX) diagnostics is presented, with the emphasis on resolution of diagnostics access issues and on diagnostics required for the early phases of operation.
Compaction Dynamics Of Metallic Nano-Foams
Abraham, Farid F
2012-01-01
We investigate, by molecular dynamics simulation, the generic features associated with the dynamic compaction of metallic nano-foams at very high strain rates. A universal feature of the dynamic compaction process is revealed as composed of two distinct regions: a growing crushed region and a leading fluid precursor. The crushed region has a density lower than the solid material and gradually grows thicker in time by "snowplowing." The trapped fluid precursor is created by ablation and/or melting of the foam filaments and the subsequent confinement of the hot atoms in a region comparable to the filament length of the foam. Quantitative characterization of nano-foam compaction dynamics is presented and the compacted form equation-of-state is discussed. We argue that high-energy foam crushing is not a shock phenomenon even though both share the snowplow feature.
Our compact with tomorrow's doctors.
Cohen, Jordan J
2002-06-01
In recent years, the image of medicine as a caring profession has been badly tarnished by a rash of critical reports in the media. In the face of this negative publicity, do young people still want to be doctors? The author reviews conventional reasons given for the declining applicant pool (e.g., issues of declining income, loss of autonomy, etc.) and posits that an additional reason may be perceptions that doctors no longer command respect and that they are being oppressed by, rather than being guardians of, the health care system. Such views challenge academic medicine to broadcast to the world a realistic picture of the fabulous opportunities and gratifications that lie ahead for the next generation of physicians. However, academic medicine must also address some current realities within medical education, such as the admission process (where at present there is a tendency to overemphasize indices of academic achievement and underemphasize the personal characteristics sought in applicants) and the acculturation process in medical school (which can often dehumanize students and convert idealistic ones into cynics). The author acknowledges that these are tough challenges. He suggests as a first step that leaders of academic medicine prepare and disseminate an explicit statement of their commitments, a kind of compact between teachers and learners of medicine. He outlines these commitments, and states his hope that by fulfilling them, the academic medicine community can make clear that medicine-which at its core is still about the doctor-patient relationship-is a true calling, not just beleaguered occupation. PMID:12063190
The definitions of charge and the invariance of charge
NASA Astrophysics Data System (ADS)
Ivezi?, T.
1992-02-01
The invariance of different collections of charges is examined for different definitions of charge. The complete equivalence of the covariant definition and the standard definition of charge is proved. Purcell's definition of the invariance of charge in terms of equality of fluxes of E is shown to be generally incorrect. Different experiments performed to verify the invariance of charge are discussed.
Novel compact circularly polarized square microstrip antenna
Wen-Shyang Chen; Chun-Kun Wu; Kin-Lu Wong
2001-01-01
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
Jacobi's Algorithm on Compact Lie Algebras
Martin Kleinsteuber; Uwe Helmke; Knut Hüper
2004-01-01
A generalization of the cyclic Jacobi algorithm is proposed that works in an arbitrary compact Lie algebra. This allows, in particular, a unifled treatment of Jacobi algorithms on difierent classes of matrices, such as, e.g., skew-symmetric or skew-Hermitian Hamiltonian matrices. Wild- berger has established global, linear convergence of the algorithm for the classical Jacobi method on compact Lie algebras. Here
Compact reflective imaging spectrometer utilizing immersed gratings
Chrisp, Michael P. (Danville, CA)
2006-05-09
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.
Compact ozone photometer based on UV LEDs
Krishnan R. Parameswaran; David M. Sonnenfroh
2010-01-01
In this paper we have demonstrated the feasibility of a compact autonomous sensor for continuous, in-situ monitoring of ambient ozone (O3) from UAVs. The primary innovation in this sensor is the combination of newly available light emitting diodes (LEDs) operating in the ultraviolet (UV) spectral region with compact, low-power, sensitive data acquisition electronics. The advent of LEDs operating in the
Stuck-at-fault test set compaction
Vanfickell, Jason Michael
2013-02-22
. In ACKNOWLEDGMENTS . . . IV TABLE OF CONTENTS, LIST OF FIGURES LIST OF TABLES . . INTRODUCTION Vl vn Fault models. . . . . . . . . . . . . Fllult Dctcction . . Excitation Balance Panel'n Mctl lc MET14ODOLOGY Program Flow. . Fault Target Selection.... 1 ormula for computation ot'thc pattern metric Figurc 3. Htgh-level SupcrDA prograin tlon chart. 1 igurc 4. Pattern Score and Fault Detections before compaction . . . . . . 13 Figure 5. Pattern Score and Dctections after compaction. . Figure 6...
Selected problems in astrophysics of compact objects
NASA Astrophysics Data System (ADS)
Sedrakian, Armen
2013-02-01
I review three problems in astrophysics of compacts stars: (i) the phase diagram of warm pair-correlated nuclear matter at sub-saturation densities at finite isospin asymmtery; (ii) the Standard Model neutrino emission from superfluid phases in neutron stars within the Landau theory of Fermi (superfluid) liquids; (iii) the beyond Standard Model physics of axionic cooling of compact stars by the Cooper pair-breaking processes.
Stauffer, Hoff
2006-04-15
The capital charge rate has a material effect in cost comparisons. Care should be taken to calculate it correctly and use it properly. The most common mistake is to use a nominal, rather than real, capital charge rate. To make matters worse, the common short-cut formula does not work well. (author)
NASA Technical Reports Server (NTRS)
Purvis, C. K.
1979-01-01
A model to predict spacecraft charging effects in the Jovian magnetosphere was developed for the preliminary design of a Jupiter probe. Charging calculations made with this model are presented and discussed. Differential potentials between interior and exterior surfaces and between sunlit and dark exterior surfaces are predicted to be in the kilovolt range.
Nuclear Charge Radii Systematics
NASA Astrophysics Data System (ADS)
Marinova, Krassimira
2015-09-01
This paper is a brief overview of the existing systematics on nuclear mean square charge radii, obtained by a combined analysis of data from different types of experiment. The various techniques yielding data on nuclear charge radii are summarized. Their specific feature complexities and the accuracy and precision of the obtained information are also discussed.
NASA Astrophysics Data System (ADS)
S, Sreekanth T.
begin{center} Large Large Rain Drop Charge Sensor Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , S. Murali Das (2) *Atmospheric Sciences Division, Centre for Earth Science Studies, Thiruvananthapuram 695011 (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) Kavyam, Manacaud, Thiruvananthapuram 695009 begin{center} ABSTRACT To study the inter-relations with precipitation electricity and precipitation microphysical parameters a rain drop charge sensor was designed and developed at CESS Electronics & Instrumentation Laboratory. Simultaneous measurement of electric charge and fall speed of rain drops could be done using this charge sensor. A cylindrical metal tube (sensor tube) of 30 cm length is placed inside another thick metal cover opened at top and bottom for electromagnetic shielding. Mouth of the sensor tube is exposed and bottom part is covered with metal net in the shielding cover. The instrument is designed in such a way that rain drops can pass only through unhindered inside the sensor tube. When electrically charged rain drops pass through the sensor tube, it is charged to the same magnitude of drop charge but with opposite polarity. The sensor tube is electrically connected the inverted input of a current to voltage converter operational amplifier using op-amp AD549. Since the sensor is electrically connected to the virtual ground of the op-amp, the charge flows to the ground and the generated current is converted to amplified voltage. This output voltage is recorded using a high frequency (1kHz) voltage recorder. From the recorded pulse, charge magnitude, polarity and fall speed of rain drop are calculated. From the fall speed drop diameter also can be calculated. The prototype is now under test running at CESS campus. As the magnitude of charge in rain drops is an indication of accumulated charge in clouds in lightning, this instrument has potential application in the field of risk and disaster management. By knowing the charge magnitude of initial drops from a precipitation event, gross cloud charge can be estimated and necessary precautions can be taken during convective cloud events. Being a site of high lightning incidence in tropics, Kerala state is affected in India and calls for much attention in lightning hazards mitigation. Installing this charge sensor and atmospheric electric field mill, an attempt to a better warning system can be attempted.
Survival of charged rho condensation at high temperature and density
Hao Liu; Lang Yu; Mei Huang
2015-07-21
The charged vector $\\rho$ mesons in the presence of external magnetic fields at finite temperature $T$ and chemical potential $\\mu$ have been investigated in the framework of the Nambu--Jona-Lasinio model. We compute the masses of charged $\\rho$ mesons numerically as a function of the magnetic field for different values of temperature and chemical potential. The self-energy of the $\\rho$ meson contains the quark-loop contribution, i.e. the leading order contribution in $1/N_c$ expansion. The charged $\\rho$ meson mass decreases with the magnetic field and drops to zero at a critical magnetic field $eB_c$, which means that the charged vector meson condensation, i.e. the electromagnetic superconductor can be induced above the critical magnetic field. Surprisingly, it is found that the charged $\\rho$ condensation can even survive at high temperature and density. At zero temperature, the critical magnetic field just increases slightly with the chemical potential, which indicates that the charged $\\rho$ condensation might occur inside compact stars. At zero density, in the temperature range $0.2-0.5~ {\\rm GeV}$, the critical magnetic field for charged $\\rho$ condensation is in the range of $0.2-0.6~ {\\rm GeV}^2$, which indicates that the high temperature electromagnetic superconductor could be created at LHC.
Technology Selections for Cylindrical Compact Fabrication
Jeffrey A. Phillips
2010-10-01
A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.
Dynamic compaction of tungsten carbide powder.
Gluth, Jeffrey Weston; Hall, Clint Allen; Vogler, Tracy John; Grady, Dennis Edward
2005-04-01
The shock compaction behavior of a tungsten carbide powder was investigated using a new experimental design for gas-gun experiments. This design allows the Hugoniot properties to be measured with reasonably good accuracy despite the inherent difficulties involved with distended powders. The experiments also provide the first reshock state for the compacted powder. Experiments were conducted at impact velocities of 245, 500, and 711 m/s. A steady shock wave was observed for some of the sample thicknesses, but the remainder were attenuated due to release from the back of the impactor or the edge of the sample. The shock velocity for the powder was found to be quite low, and the propagating shock waves were seen to be very dispersive. The Hugoniot density for the 711 m/s experiment was close to ambient crystal density for tungsten carbide, indicating nearly complete compaction. When compared with quasi-static compaction results for the same material, the dynamic compaction data is seen to be significantly stiffer for the regime over which they overlap. Based on these initial results, recommendations are made for improving the experimental technique and for future work to improve our understanding of powder compaction.
Compaction of Ductile and Fragile Grains
NASA Astrophysics Data System (ADS)
Creissac, S.; Pouliquen, O.; Dalloz-Dubrujeaud, B.
2009-06-01
The compaction of powders into tablets is widely used in several industries (cosmetics, food, pharmaceutics…). In all these industries, the composition of the initial powder is complex, and the behaviour under compaction is not well known, also the mechanical behaviour of the tablets. The aim of this paper is to understand the behaviour (pressure vs density) of a simplified media made of fragile and ductile powders, varying the relative ratio of each powder. Some compaction experiments were carried out with glass beads (fragile) and Polyethylen Glycol powder (ductile). We observe two typical behaviours, depending on the relative volumic fraction of each component. A transition is pointed out, observing the evolution of the slope of the curve pressure/density. This transition is explained by geometrical considerations during compaction. A model is proposed, based on the assumption that the studied media can be compare to a diphasic material with a continuous phase (the ductile powder) and a discrete phase (the fragile powder). The result of this model is compare to the experimental results of compaction, and give a good prediction of the behaviour of the different mixing, knowing the behaviour of the ductile and the fragile phase separately. These results were also interpreted in terms of Heckel parameter which characterizes the ability of the powder to deform plastically under compaction. Some mechanical tests were also performed to compare the mechanical resitance of the obtained tablets.
Charged Sectors, Spin and Statistics in Quantum Field Theory on Curved Spacetimes
D. Guido; R. Longo; J. E. Roberts; R. Verch
2001-01-01
The first part of this paper extends the Doplicher-Haag-Roberts theory of superselection sectors to quantum field theory on arbitrary globally hyperbolic spacetimes. The statistics of a superselection sector may be defined as in flat spacetime and each charge has a conjugate charge when the spacetime possesses non-compact Cauchy surfaces. In this case, the field net and the gauge group can
Compact Q-balls and Q-shells in a scalar electrodynamics
Arodz, H.; Lis, J.
2009-02-15
We investigate spherically symmetric nontopological solitons in electrodynamics with a scalar field self-interaction U{approx}|{psi}| taken from the complex signum-Gordon model. We find Q-balls for small absolute values of the total electric charge Q, and Q-shells when |Q| is large enough. In both cases the charge density exactly vanishes outside certain compact regions in the three-dimensional space. The dependence of the total energy E of small Q-balls on the total electric charge has the form E{approx}|Q|{sup 5/6}, while in the case of very large Q-shells, E{approx}|Q|{sup 7/6}.
Compact Schemes for Acoustics in the Frequency Domain
Kentucky, University of
for the compact scheme for the Helmholtz equation and an e#11;ective strategy of incorporating absorbing boundary compact schemes for the numerical solution of the Helmholtz problem. The 9-point compact di#11;erence and by obtaining the representation for the solution of the PDE. Thus the derivation of compact schemes and its
THE ELEMENTARY GEOMETRIC STRUCTURE OF COMPACT LIE GROUPS
of some of the basic structure theorem* *s for compact Lie groups. The goal is to take a fresh look. x1. Introduction A compact Lie group G is a compact differentiable manifold together, the multiplicative group of u* *nit quaternions, or the group SO n of rotations in Euclidean n-space. Compact Lie
Charged anisotropic matter with linear or nonlinear equation of state
Victor Varela; Farook Rahaman; Saibal Ray; Koushik Chakraborty; Mehedi Kalam
2010-09-04
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.
Charged anisotropic matter with linear or nonlinear equation of state
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
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.
Stylolite compaction and stress models
NASA Astrophysics Data System (ADS)
Koehn, D.; Ebner, M.; Renard, F.; Toussaint, R.
2009-04-01
Stylolites are rough dissolution seams that develop during pressure solution in the Earth's crust. Especially in limestone quarries they exhibit a spectacular roughness with spikes and large columns. They are visible as dark lines of residual clays and other non-dissolvable components in the white limestone. The roughening phenomena seems to be universal since stylolites can also be found in quarzites, mylonites and all kinds of rocks that undergo pressure solution. The genesis of stylolites is not well understood even though they have been used to estimate compaction and to determine the direction of the main compressive stress. We have developed a numerical model to study the dynamic development of the roughness and its dependence on stress. Based on the model we present estimates of finite strain and depth of burial. The numerical stylolites are studied in two ways: the temporal evolution of the roughness on one hand and the fractal characteristics of the roughness on the other hand. In addition we vary the noise in the model and illustrate the importance of the grain size on the roughening process. Surface energies are dominant for small wavelengths and the initial stylolite growth is non-linear and as slow as a diffusive process. However, once a critical wavelength is reached the elastic regime becomes dominant and the growth is still non-linear but not as strong as in the surface energy dominated case. The growth of the roughness speeds up and teeth structures develop. Depending on the system size the growth will reach a third regime where saturation is reached and the roughness stays constant. We will present a scaling law based on these findings that can be used to estimate finite strain from natural stylolites. The roughness of the stylolite itself is self-affine with two different roughness exponents. The switch from one exponent to the other is dependent on stress. We show how stylolites can thus be used as palaeo-stress-gauges. A variation of the initial noise in the system does only change the stylolite growth significantly, if the absolute size of the noise is changed, for example the grain size in a sample. The roughness exponents do not change but the switch from slow to fast growth comes earlier so that the finial stylolite will look different.
Tzul, Franco O.; Schweiker, Katrina L.; Makhatadze, George I.
2015-01-01
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
Relativistically spinning charged sphere
Lynden-Bell, D. [Institute of Astronomy, The Observatories, Madingley Road, Cambridge, CB3 0HA (United Kingdom) and Clare College, Cambridge (United Kingdom)
2004-11-15
When the equatorial spin velocity v of a charged conducting sphere approaches c, the Lorentz force causes a remarkable rearrangement of the total charge q. Charge of that sign is confined to a narrow equatorial belt at latitudes b{<=}{radical}(3)(1-v{sup 2}/c{sup 2}){sup 1/2} while charge of the opposite sign occupies most of the sphere's surface. The change in field structure is shown to be a growing contribution of the 'magic' electromagnetic field of the charged Kerr-Newman black hole with Newton's G set to zero. The total charge within the narrow equatorial belt grows as (1-v{sup 2}/c{sup 2}){sup -(1/4)} and tends to infinity as v approaches c. The electromagnetic field, Poynting vector, field angular momentum, and field energy are calculated for these configurations. Gyromagnetic ratio, g factor, and electromagnetic mass are illustrated in terms of a 19th century electron model. Classical models with no spin had the small classical electron radius e{sup 2}/mc{sup 2}{approx} a hundredth of the Compton wavelength, but models with spin take that larger size but are so relativistically concentrated to the equator that most of their mass is electromagnetic. The method of images at inverse points of the sphere is shown to extend to charges at points with imaginary coordinates.
Detecting Charged Particles Using Charge Injection Devices
NASA Astrophysics Data System (ADS)
Fletcher, K. A.; Apker, B.; Hammond, S.; Punaro, J.; Surman, G.; Marshall, F. J.; Laine, J.
2004-11-01
CID cameras, used for x-ray imaging on the University of Rochester's OMEGA laser system, can also be used to detect charged particles, such as those emitted in fusion reactions. The charged-particle sensitivity of CID cameras is being measured using both radioactive alpha sources and fusion reactions generated by the SUNY Geneseo 2 MV Van de Graaff accelerator. To determine the efficiency of such measurements, we simultaneously detected the energetic particles with a surface barrier detector and a CID placed at identical angles in the scattering chamber. Future work will focus on tests of the system using inertial confinement fusion products at the OMEGA laser facility. (Supported in part by the U.S. Department of Energy through the University of Rochester's Laboratory for Laser Energetics.)
taking charge : optimizing urban charging infrastructure for shared electric vehicles
Subramani, Praveen
2012-01-01
This thesis analyses the opportunities and constraints of deploying charging infrastructure for shared electric vehicles in urban environments. Existing electric vehicle charging infrastructure for privately owned vehicles ...
Ainalem, Marie-Louise; Bartles, Andrew; Muck, Joscha; Dias, Rita S.; Carnerup, Anna M.; Zink, Daniele; Nylander, Tommy
2014-01-01
There is an increasing interest in achieving gene regulation in biotechnological and biomedical applications by using synthetic DNA-binding agents. Most studies have so far focused on synthetic sequence-specific DNA-binding agents. Such approaches are relatively complicated and cost intensive and their level of sophistication is not always required, in particular for biotechnological application. Our study is inspired by in vivo data that suggest that DNA compaction might contribute to gene regulation. This study exploits the potential of using synthetic DNA compacting agents that are not sequence-specific to achieve gene regulation for in vitro systems. The semi-synthetic in vitro system we use include common cationic DNA-compacting agents, poly(amido amine) (PAMAM) dendrimers and the surfactant hexadecyltrimethylammonium bromide (CTAB), which we apply to linearized plasmid DNA encoding for the luciferase reporter gene. We show that complexing the DNA with either of the cationic agents leads to gene expression inhibition in a manner that depends on the extent of compaction. This is demonstrated by using a coupled in vitro transcription-translation system. We show that compaction can also protect DNA against degradation in a dose-dependent manner. Furthermore, our study shows that these effects are reversible and DNA can be released from the complexes. Release of DNA leads to restoration of gene expression and makes the DNA susceptible to degradation by Dnase. A highly charged polyelectrolyte, heparin, is needed to release DNA from dendrimers, while DNA complexed with CTAB dissociates with the non-ionic surfactant C12E5. Our results demonstrate the relation between DNA compaction by non-specific DNA-binding agents and gene expression and gene regulation can be achieved in vitro systems in a reliable dose-dependent and reversible manner. PMID:24671109
Susumu, Kimihiro; Oh, Eunkeu; Delehanty, James B; Blanco-Canosa, Juan B; Johnson, Brandy J; Jain, Vaibhav; Hervey, William Judson; Algar, W Russ; Boeneman, Kelly; Dawson, Philip E; Medintz, Igor L
2011-06-22
We describe the synthesis of a series of four different ligands which are used to prepare hydrophilic, biocompatible luminescent quantum dots (QDs) and gold nanoparticles (AuNPs). Overall, the ligands are designed to be compact while still imparting a zwitterionic character to the NPs. Ligands are synthesized appended to a bidentate dihydrolipoic acid- (DHLA) anchor group, allowing for high-affinity NP attachment, and simultaneously incorporate tertiary amines along with carboxyl and/or hydroxyl groups. These are placed in close proximity within the ligand structure and their capacity for joint ionization imparts the requisite zwitterionic nature to the nanocrystal. QDs functionalized with the four different compact ligands were subjected to extensive physical characterization including surface charge, wettability, hydrodynamic size, and tolerance to a wide pH range or high salt concentration over time. The utility of the compact ligand coated QDs was further examined by testing of direct conjugation to polyhistidine-appended protein and peptides, aqueous covalent-coupling chemistry, and the ability to engage in Förster resonance energy transfer (FRET). Conjugating cell penetrating peptides to the compact ligand coated QD series facilitated their rapid and efficient cellular uptake, while subsequent cytotoxicity tests showed no apparent decreases in cell viability. In vivo biocompatibility was also demonstrated by microinjecting the compact ligand coated QDs into cells and monitoring their stability over time. Inherent benefits of the ligand design could be extended beyond QDs as AuNPs functionalized with the same compact ligand series showed similar colloidal properties. The strong potential of these ligands to expand NP capabilities in many biological applications is highlighted. PMID:21612225
L. B. Okun
2006-02-13
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.
Glenn Barnich; Cedric Troessaert
2011-10-25
The surface charges associated with the symmetries of asymptotically flat four dimensional spacetimes at null infinity are constructed. They realize the symmetry algebra in general only up to a field-dependent central extension that satisfies a suitably generalized cocycle condition. This extension vanishes when using the globally well defined BMS algebra. For the Kerr black hole and the enlarged BMS algebra with both supertranslations and superrotations, some of the supertranslations charges diverge whereas there are no divergences for the superrotation charges. The central extension is proportional to the rotation parameter and involves divergent integrals on the sphere.
Barnich, Glenn
2011-01-01
The surface charges associated with the symmetries of asymptotically flat four dimensional spacetimes at null infinity are constructed. They realize the symmetry algebra in general only up to a field-dependent central extension that satisfies a suitably generalized cocycle condition. This extension vanishes when using the globally well defined BMS algebra. For the Kerr black hole and the enlarged BMS algebra with both supertranslations and superrotations, some of the supertranslations charges diverge whereas there are no divergences for the superrotation charges. The central extension is proportional to the rotation parameter and involves divergent integrals on the sphere.
42 CFR 405.506 - Charges higher than customary or prevailing charges or lowest charge levels.
Code of Federal Regulations, 2011 CFR
2011-10-01
...charges or lowest charge levels. A charge which...medical or other health service, or the prevailing...applicable lowest charge level may be found to...charge, and only if it is acceptable medical or medical service practice in the...
Chen, Y; Guethlein, G; Caporaso, G; Sampayan, S; Blackfield, D; Cook, E; Falabella, S; Harris, J; Hawkins, S; Nelson, S; Poole, B; Richardson, R; Watson, J; Weir, J; Pearson, D
2009-04-23
A compact proton accelerator for cancer treatment is being developed by using the high-gradient dielectric insulator wall (DWA) technology [1-4]. We are testing all the essential DWA components, including a compact proton source, on the First Article System Test (FAST). The configuration and progress on the injector and FAST will be presented.
A two-phase model for compaction and damage 2. Applications to compaction, deformation and
1 A two-phase model for compaction and damage 2. Applications to compaction, deformation of California, Los Angeles, California Abstract. New equations for the dynamics of a two-phase mixture the two phases, including the possibility of surface energy at the interface between the phases
A study of compaction bands originating from cracks, notches, and compacted defects
Einat, Aharonov
; Porous rock; Spring network model 1. Introduction Compaction bands (CBs) were recently identified spontaneously in high porosity rock under certain compressive stress conditions. Recent experiments show present an elasto-plastic model, used to investigate compaction band formation under a variety of boundary
Shear-enhanced compaction in viscoplastic rocks
NASA Astrophysics Data System (ADS)
Yarushina, V. M.; Podladchikov, Y. Y.
2012-04-01
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.
Modeling of planetesimal compaction by hot pressing
NASA Astrophysics Data System (ADS)
Neumann, W.; Breuer, D.; Spohn, T.
2014-07-01
Compaction of initially porous material prior to melting is an important process that has influenced the interior structure and the thermal evolution of planetesimals in their early history. On one hand, compaction decreases the porosity resulting in a reduction of the radius. On the other hand, the loss of porosity results in an increase of the thermal conductivity of the material and, thus, in a more efficient cooling. Porosity loss by hot pressing is the most efficient process of compaction in planetesimals and can be described by creep flow, which depends on temperature and stress. Hot pressing has been repeatedly modeled using a simplified approach, for which the porosity is gradually reduced in some fixed temperature interval between ~650 K and 700 K [see e.g. 1--3]. This approach neglects the dependence of compaction on stress. In the present study [see 4], we compare this ''parametrized'' method with a self-consistent calculation of porosity loss via a ''creep-related'' approach. We use our thermal evolution model from previous studies [5] to model compaction of an initially porous ordinary chondritic body and consider four basic packings of spherical dust grains (simple cubic, orthorhombic, rhombohedral, and body-centered cubic). Depending on the grain packing, we calculate the effective stress and the associated porosity change via the thermally activated creep flow. For comparison, compaction is also modeled by simply reducing the initial porosity linearly to zero between 650 and 700 K. Since we are interested in thermal metamorphism and not melting, we only consider bodies that experience a maximum temperature below the solidus temperature of the metal phase. For the creep related approach, the temperature interval in which compaction takes place depends strongly on the size of the planetesimal and is not fixed as assumed in the parametrized approach. Depending on the radius, the initial grain size, the activation energy, the initial porosity, and the specific packing of the dust grains, the temperature interval lies within 600--1200 K. This finding implies that the parametrized approach strongly overestimates compaction and underestimates the maximal temperature. For the cases considered, the post-compaction porous layer retained at the surface, is a factor of 2.5 to 4.5 thicker for the creep-related approach. The difference in the temperature evolution between the two approaches increases with decreasing radius, and the maximal temperature can deviate by about 40 % for small bodies.
Diagnostics of soil compaction in steppe zone
NASA Astrophysics Data System (ADS)
Sorokin, Alexey; Kust, German
2014-05-01
Land degradation and desertification are among the major challenges in steppe zone, and leads the risks of food security in affected areas. Soil compaction is one of the basic reasons of degradation of arable land. The processes of soil compaction have different genesis. Knowledge of soil compaction mechanisms and their early diagnostics permit to accurately forecast velocity and degree of degradation processes as well as to undertake effective preventive measures and land reclamation activities. Manifestations of soil compaction and degradation of soil structure due to vertic, alkaline and and mechanical (agro-) compaction, as well as caused by combination of these processes in irrigated and rainfed conditions were studied in four model plots in Krasnodar and Saratov regions of Russia. Typic chernozems, solonetz and kashtanozem solonetz, south chernozem and dark-kashtanozem soils were under investigation. Morphological (mesomorphological, micromorphological and microtomographic) features, as well as number of physical (particle size analyses, water-peptizable clays content (WPC), swelling and shrinking, bulk density and moisture), chemical (humus, pH, CAC, EC), and mineralogical (clay fraction) properties were investigated. Method for grouping soil compaction types by morphological features was proposed. It was shown that: - overcompacted chernozems with vertic features has porosity close to natural chernozems (about 40%), but they had the least pore diameter (7-12 micron) among studied soils. Solonetzic soils had the least amount of "pore-opening" (9%). - irrigation did not lead to the degradation of soil structure on micro-level. - "mechanically" (agro-) compacted soils retained an intra-aggregate porosity. - studied soils are characterized by medium and heavy particle size content (silt [<0.1mm] of 30-60%). Subsoil horizons of chernozems with vertic and alkaline features were the heaviest by particle size content. - the share of WPC to clay ratio was 40% in average, this ratio in vertic and alkaline soils was up to more than 70%. - overcompacted chernozems with vertic features has the swelling degree of 17-25%, all studied soils have the maximum value of swelling degree in subsoil compacted horizon. - humus content varied from 2 to 4%, pH - from 6.9 to 8.2. Studied soils were saturated with basics, Ca of 30 mg*eq/100g and more, Na was more relevant to compacted solonetz and solonetz-like soils (up to 4.3 mg*eq/100g)
Carbeck, J.D.; Gao, J.; Smith, R.D.; Whitesides, G.M.; Severs, J.C.; Wu, Q.
1998-12-17
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.
Energy release model of compaction band propagation
NASA Astrophysics Data System (ADS)
Rudnicki, J. W.; Sternlof, K. R.
2005-08-01
The elastic strain energy released per unit advance of a compaction band in an infinite layer of thickness h is used to identify and assess quantities relevant to propagation of isolated compaction bands observed in outcrop. If the elastic moduli of the band and the surrounding host material are similar and the band is much thinner than the layer, the energy released is simply ?+?h$\\epsilon$p where ?+ is the compressive stress far ahead of the band edge, ?h is the thickness of the band and $\\epsilon$p is the uniaxial inelastic compactive strain in the band. Using representative values inferred from field data yields an energy release rate of 40 kJ/m2, which is roughly comparable with compaction energies inferred from axisymmetric compression tests on notched sandstone samples. This suggests that a critical value of the energy release rate may govern propagation, although the particular value is likely to depend on the rock type and details of the compaction process.
Strategy Guideline: Compact Air Distribution Systems
Burdick, A.
2013-06-01
This Strategy Guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward the exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.
Granular Charge Buildup Eyjafjallajoku
Anlage, Steven
accelerationin acrylic container by linear motor · Sand charges during collisions and discharges at aluminum R Linear Motor Vreg C r Motor Scope armoto high Line Sand-filled cellScope ground #12;Collision
Charged Schrodinger black holes
Adams, Allan
We construct charged and rotating asymptotically Schrödinger black hole solutions of type IIB supergravity. We begin by obtaining a closed-form expression for the null Melvin twist of a broad class of type IIB backgrounds, ...
NASA Technical Reports Server (NTRS)
Gregory, D. A.; Stocks, C. D.
1983-01-01
Improved version of Faraday cup increases accuracy of measurements of flux density of charged particles incident along axis through collection aperture. Geometry of cone-and-sensing cup combination assures most particles are trapped.
Primitive Virtual Negative Charge
Kim, Kiyoung
2008-01-01
Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction electric equilibrium of the earth is discussed, especially about the electric field and magnetic field of the earth. For unsettled phenomena related with the earth's gravity, such as antigravity phenomenon, gravity anomalies during the solar eclipses, the connection between geomagnetic storms and earthquakes, etc., possible explanations are discussed.
Primitive Virtual Negative Charge
Kiyoung Kim
2008-11-04
Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction electric equilibrium of the earth is discussed, especially about the electric field and magnetic field of the earth. For unsettled phenomena related with the earth's gravity, such as antigravity phenomenon, gravity anomalies during the solar eclipses, the connection between geomagnetic storms and earthquakes, etc., possible explanations are discussed.
Granular matter: Charges dropped
NASA Astrophysics Data System (ADS)
Spahn, Frank; Sei?, Martin
2015-09-01
Granular charging can create some spectacular interactions, but gravity obscures our ability to observe and understand them. A neat desktop experiment circumvents this problem, shining a light on granular clustering -- and perhaps even planet formation.
NASA Astrophysics Data System (ADS)
van Wezel, Jasper; Flicker, Felix
2015-03-01
Incommensurate charge density waves occur in a large variety of materials in one, two and even three dimensions. As a function of decreasing temperature or applied pressure, the propagation vector characterizing such charge order typically evolves smoothly towards a commensurate value, before discontinuously jumping to a fully commensurate phase. This so-called lock-in transition is often explained in terms of a proliferation of discommensurations, which separate local regions of commensurate CDW within a globally incommensurate structure. Here, we argue that in strongly incommensurate systems with a sharply peaked electronic susceptibility, a second possibility exists. Rather than forming a regular array of discommensurations, we show that within an extended region of parameter space, the system may lower its free energy further by forming a quasicrystalline charge ordered state. The characteristic properties of this novel implementation of a quasicrystal, as well as its effect on the phase diagram and wave vector evolution of typical incommensurate charge ordered materials will be discussed.
NASA Technical Reports Server (NTRS)
deWit, A.; Cohn, N.
1999-01-01
The Netherlands Directorate General of Civil Aviation (DGCA) commissioned Hague Consulting Group (HCG) to complete a benchmark study of airport charges at twenty eight airports in Europe and around the world, based on 1996 charges. This study followed previous DGCA research on the topic but included more airports in much more detail. The main purpose of this new benchmark study was to provide insight into the levels and types of airport charges worldwide and into recent changes in airport charge policy and structure, This paper describes the 1996 analysis. It is intended that this work be repeated every year in order to follow developing trends and provide the most up-to-date information possible.
NASA Astrophysics Data System (ADS)
Klimov, A. S.; Burdovitsin, V. A.; Zenin, A. A.; Oks, E. M.; Khasanov, O. L.; Dvilis, E. S.; Khasanov, A. O.
2015-08-01
It is shown that a noticeable role in the electron beam charge neutralization in the course of electron-beam sintering of compacted silicon carbide samples is played, as the sample temperature increases, by the electrical conductivity of a sample being sintered, as well as by thermionic emission from its surface. Experimental results obtained for compacted silicon carbide are used to determine its energy gap width and the electron work function.
Radioactive decays of highly-charged ions
NASA Astrophysics Data System (ADS)
Gao, B. S.; Najafi, M. A.; Atanasov, D. R.; Blaum, K.; Bosch, F.; Brandau, C.; Chen, X. C.; Dillmann, I.; Dimopoulou, Ch.; Faestermann, Th.; Geissel, H.; Gernhäuser, R.; Hillenbrand, P.-M.; Kovalenko, O.; Kozhuharov, C.; Litvinov, S. A.; Litvinov, Yu. A.; Maier, L.; Nolden, F.; Piotrowski, J.; Sanjari, M. S.; Scheidenberger, C.; Spillmann, U.; Steck, M.; Stöhlker, Th.; Trageser, Ch.; Tu, X. L.; Weick, H.; Winckler, N.; Xu, H. S.; Yamaguchi, T.; Yan, X. L.; Zhang, Y. H.; Zhou, X. H.
2015-05-01
Access to stored and cooled highly-charged radionuclides offers unprecedented opportunities to perform high-precision investigations of their decays. Since the few-electron ions, e.g. hydrogen- or helium-like ions, are quantum mechanical systems with clear electronic ground state configurations, the decay studies of such ions are performed under well-defined conditions and allow for addressing fundamental aspects of the decay process. Presented here is a compact review of the relevant experiments conducted at the Experimental Storage Ring ESR of GSI. A particular emphasis is given to the investigations of the two-body beta decay, namely the bound-state ?-decay and its time-mirrored counterpart, orbital electron-capture.
A Novel Spacecraft Charge Monitor for LEO
NASA Technical Reports Server (NTRS)
Goembel, Luke
2004-01-01
Five years ago we introduced a new method for measuring spacecraft chassis floating potential relative to the space plasma (absolute spacecraft potential) in low Earth orbit. The method, based on a straightforward interpretation of photoelectron spectra, shows promise for numerous applications, but has not yet been tried. In the interest of testing the method, and ultimately supplying another tool for measuring absolute spacecraft charge, we are producing a flight prototype Spacecraft Charge Monitor (SCM) with support from NASA's Small Business Innovation Research (SBIR) program. Although insight into the technique came from data collected in space over two decades ago, very little data are available. The data indicate that it may be possible to determine spacecraft floating potential to within 0.1 volt each with the SCM second under certain conditions. It is debatable that spacecraft floating potential has ever been measured with such accuracy. The compact, easily deployed SCM also offers the advantage of long-term stability in calibration. Accurate floating potential determinations from the SCM could be used to correct biases in space plasma measurements and evaluate charge mitigation and/or sensing devices. Although this paper focuses on the device's use in low Earth orbit (LEO), the device may also be able to measure spacecraft charge at higher altitudes, in the solar wind, and in orbits around other planets. The flight prototype SCM we are producing for delivery to NASA in the third quarter of 2004 will measure floating potential from 0 to -150 volts with 0.1 volt precision, weigh approximately 600-700 grams, consume approximately 2 watts, and will measure approximately 8 x 10 x 17 cm.
PrP charge structure encodes interdomain interactions
Martínez, Javier; Sánchez, Rosa; Castellanos, Milagros; Makarava, Natallia; Aguzzi, Adriano; Baskakov, Ilia V.; Gasset, María
2015-01-01
Almost all proteins contain charged residues, and their chain distribution is tailored to fulfill essential ionic interactions for folding, binding and catalysis. Among proteins, the hinged two-domain chain of the cellular prion protein (PrPC) exhibits a peculiar charge structure with unclear consequences in its structural malleability. To decipher the charge design role, we generated charge-reverted mutants for each domain and analyzed their effect on conformational and metabolic features. We found that charges contain the information for interdomain interactions. Use of dynamic light scattering and thermal denaturation experiments delineates the compaction of the ?-fold by an electrostatic compensation between the polybasic 23–30 region and the ?3 electronegative surface. This interaction increases stability and disfavors fibrillation. Independently of this structural effect, the N-terminal electropositive clusters regulate the ?-cleavage efficiency. In the fibrillar state, use of circular dichroism, atomic-force and fluorescence microscopies reveal that the N-terminal positive clusters and the ?3 electronegative surface dictate the secondary structure, the assembly hierarchy and the growth length of the fibril state. These findings show that the PrP charge structure functions as a code set up to ensure function and reduce pathogenic routes. PMID:26323476
PrP charge structure encodes interdomain interactions.
Martínez, Javier; Sánchez, Rosa; Castellanos, Milagros; Makarava, Natallia; Aguzzi, Adriano; Baskakov, Ilia V; Gasset, María
2015-01-01
Almost all proteins contain charged residues, and their chain distribution is tailored to fulfill essential ionic interactions for folding, binding and catalysis. Among proteins, the hinged two-domain chain of the cellular prion protein (PrP(C)) exhibits a peculiar charge structure with unclear consequences in its structural malleability. To decipher the charge design role, we generated charge-reverted mutants for each domain and analyzed their effect on conformational and metabolic features. We found that charges contain the information for interdomain interactions. Use of dynamic light scattering and thermal denaturation experiments delineates the compaction of the ?-fold by an electrostatic compensation between the polybasic 23-30 region and the ?3 electronegative surface. This interaction increases stability and disfavors fibrillation. Independently of this structural effect, the N-terminal electropositive clusters regulate the ?-cleavage efficiency. In the fibrillar state, use of circular dichroism, atomic-force and fluorescence microscopies reveal that the N-terminal positive clusters and the ?3 electronegative surface dictate the secondary structure, the assembly hierarchy and the growth length of the fibril state. These findings show that the PrP charge structure functions as a code set up to ensure function and reduce pathogenic routes. PMID:26323476
Cylindrically Symmetric Models of Anisotropic Compact Stars
G. Abbas; Sumara Nazeer; M. A. Meraj
2014-12-16
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$U$1820-30, Her X-1, SAX J 1808-3658. The properties of these stars have been analyzed in detail. In this setting the cosmological constant has been taken as a variable which depends on the radial coordinates. We have checked all the regularity conditions, stability and surface redshift of the compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658.
A Compact ? Model of huntingtin Toxicity*
Zhang, Qi Charles; Yeh, Tzu-lan; Leyva, Alfonso; Frank, Leslie G.; Miller, Jason; Kim, Yujin E.; Langen, Ralf; Finkbeiner, Steven; Amzel, Mario L.; Ross, Christopher A.; Poirier, Michelle A.
2011-01-01
Huntington disease results from an expanded polyglutamine region in the N terminus of the huntingtin protein. HD pathology is characterized by neuronal degeneration and protein inclusions containing N-terminal fragments of mutant huntingtin. Structural information is minimal, though it is believed that mutant huntingtin polyglutamine adopts ? structure upon conversion to a toxic form. To this end, we designed mammalian cell expression constructs encoding compact ? variants of Htt exon 1 N-terminal fragment and tested their ability to aggregate and induce toxicity in cultured neuronal cells. In parallel, we performed molecular dynamics simulations, which indicate that constructs with expanded polyglutamine ?-strands are stabilized by main-chain hydrogen bonding. Finally, we found a correlation between the reactivity to 3B5H10, an expanded polyglutamine antibody that recognizes a compact ? rich hairpin structure, and the ability to induce cell toxicity. These data are consistent with an important role for a compact ? structure in mutant huntingtin-induced cell toxicity. PMID:21209075
Capability enhancement in compact digital holographic microscopy
NASA Astrophysics Data System (ADS)
Qu, Weijuan; Wen, Yongfu; Wang, Zhaomin; Yang, Fang; Asundi, Anand
2015-03-01
A compact reflection digital holographic microscopy (DHM) system integrated with the light source and optical interferometer is developed for 3D topographic characterization and real-time dynamic inspection for Microelectromechanical systems (MEMS). Capability enhancement methods in lateral resolution, axial resolving range and large field of view for the compact DHM system are presented. To enhance the lateral resolution, the numerical aperture of a reflection DHM system is analyzed and optimum designed. To enhance the axial resolving range, dual wavelengths are used to extend the measuring range. To enable the large field of view, stitching of the measurement results is developed in the user-friendly software. Results from surfaces structures on silicon wafer, micro-optics on fused silica and dynamic inspection of MEMS structures demonstrate applications of this compact reflection digital holographic microscope for technical inspection in material science.
Compactible powders of omega-3 and ?-cyclodextrin.
Vestland, Tina Lien; Jacobsen, Øyvind; Sande, Sverre Arne; Myrset, Astrid Hilde; Klaveness, Jo
2015-10-15
Omega-3 fatty acids are used in both nutraceuticals and pharmaceuticals in the form of triglycerides and ethyl esters. Administration forms available for omega-3 include bulk oil, soft gel capsules, emulsions and some powder compositions. Cyclodextrins are substances well known for their ability to encapsulate lipophilic molecules. In the present work, powders loaded with omega-3 oil, ranging from 10 to 40% (w/w), have been prepared by vacuum drying, freeze drying or spray granulation of aqueous mixtures of omega-3 oil and ?-cyclodextrin. The powders were found to be partially crystalline by powder X-ray diffraction and to contain crystalline phases not present in pure ?-cyclodextrin, indicating true complexation. The compactibility of the powders has been explored, revealing that a dry and compactible powder can be prepared from various omega-3 oils and ?-cyclodextrin. Spray granulation was found to be the superior drying method for the preparation of compactible powders. PMID:25952853
Settlement of footing on compacted ash bed
Ramasamy, G.; Pusadkar, S.S.
2007-11-15
Compacted coal ash fills exhibit capillary stress due to contact moisture and preconsolidation stress due to the compaction process. As such, the conventional methods of estimating settlement of footing on cohesionless soils based on penetration tests become inapplicable in the case of footings on coal ash fills, although coal ash is also a cohesionless material. Therefore, a method of estimating load-settlement behavior of footings resting on coal ash fills accounting for the effect of capillary and preconsolidation stresses is presented here. The proposed method has been validated by conducting plate load tests on laboratory prepared compacted ash beds and comparing the observed and predicted load-settlement behavior. Overestimation of settlement greater than 100% occurs when capillary and preconsolidation stresses are not accounted for, as is the case in conventional methods.
Anisotropic Compact stars with variable cosmological constant
Sk. Monowar Hossein; Farook Rahaman; Jayanta Naskar; Mehedi Kalam; Saibal Ray
2012-11-22
Recently the small value of the cosmological constant and its ability to accelerate the expansion of the Universe is of great interest. We discuss the possibility of forming of anisotropic compact stars from this cosmological constant as one of the competent candidates of dark energy. For this purpose we consider the analytical solution of Krori and Barua metric. We take the radial dependence of cosmological constant and check all the regularity conditions, TOV equations, stability and surface redshift of the compact stars. It has been shown as conclusion that this model is valid for any compact star and we have cited $4U 1820-30$ as a specific example of that kind of star.
Estimating hydraulic conductivity of compacted clay liners
Benson, C.H.; Zhai, Huaming; Wang, Xiaodong (Univ. of Wisconsin, Madison, WI (United States). Dept. of Civil Environmental Engineering)
1994-02-01
A database is described that contains laboratory measurements of hydraulic conductivity and associated soil properties that were extracted from construction reports for compacted soil liners. The database contains measurements conducted on a wide variety of soils from 67 landfills in North America. The database was used to evaluate relationships between hydraulic conductivity, compositional factors, and compaction variables and to identify minimum values for soil properties that are likely to yield a geometric mean hydraulic conductivity [<=]1 [times] 10[sup [minus]7] cm/s. A graphical analysis suggests that a geometric mean hydraulic conductivity [<=]1 [times] 10[sup [minus]7] cm/s can be achieved if the liquid limit [>=]20, the plasticity index [>=]7, the percent fines (< No. 200 sieve) [>=]30%, and the percent clay (<2 [mu]m) [>=]15%. A multivariate regression equation was also developed that can be used to estimate the geometric mean hydraulic conductivity as a function of soil composition and compaction conditions.
Anisotropic Compact Stars with Variable Cosmological Constant
NASA Astrophysics Data System (ADS)
Hossein, Sk. Monowar; Rahaman, Farook; Naskar, Jayanta; Kalam, Mehedi; Ray, Saibal
2012-12-01
Recently, the small value of the cosmological constant and its ability to accelerate the expansion of the universe is of great interest. We discuss the possibility of forming of anisotropic compact stars from this cosmological constant as one of the competent candidates of dark energy. For this purpose, we consider the analytical solution of Krori and Barua metric. We take the radial dependence of cosmological constant and check all the regularity conditions, TOV equations, stability and surface redshift of the compact stars. It has been shown as conclusion that this model is valid for any compact star and we have cited 4U 1820-30 as a specific example of that kind of star.
Compaction of batch for flat glass
Kalygin, V.G.; Chekov, O.S.; Kozlova, L.N.; Nazarov, V.I.; Pankova, N.A.
1985-11-01
The quality of the batch for flat glass can be improved by granulating it, in particular, by compacting it in roller presses with a smooth surface, a method which makes it possible to compact glass batches with a wide range of chemical and grain compositions. It does not require the finished product to be dried. It is outstanding in the simplicity of the molding equipment and in its productivity, of considerable significance in multi-ton production of flat glass. The authors study here some properties of batches which must be taken into account when calculating and selecting compaction equipment. The experimental batch comprised aluminum borosilicate for glass fiber, M /SUB m/ = 0.31 with 10% B2O3; in a lead crystal batch, M /SUB m/ = 0.29 with 24% PbO.
Impacts by Compact Ultra Dense Objects
NASA Astrophysics Data System (ADS)
Birrell, Jeremey; Labun, Lance; Rafelski, Johann
2012-03-01
We propose to search for nuclear density or greater compact ultra dense objects (CUDOs), which could constitute a significant fraction of the dark matter [1]. Considering their high density, the gravitational tidal forces are significant and atomic-density matter cannot stop an impacting CUDO, which punctures the surface of the target body, pulverizing, heating and entraining material near its trajectory through the target [2]. Because impact features endure over geologic timescales, the Earth, Moon, Mars, Mercury and large asteroids are well-suited to act as time-integrating CUDO detectors. There are several potential candidates for CUDO structure such as strangelet fragments or more generally dark matter if mechanisms exist for it to form compact objects. [4pt] [1] B. J. Carr, K. Kohri, Y. Sendouda, & J.'i. Yokoyama, Phys. Rev. D81, 104019 (2010). [0pt] [2] L. Labun, J. Birrell, J. Rafelski, Solar System Signatures of Impacts by Compact Ultra Dense Objects, arXiv:1104.4572.
The birthplace of compact groups of galaxies
NASA Technical Reports Server (NTRS)
Ramella, Massimo; Diaferio, Antonaldo; Geller, Margaret J.; Huchra, John P.
1994-01-01
We use complete redshift surveys to study the redshift neighborhoods of 38 Hickson compact groups (HCGs). Twenty-nine of these HCGs (76%) are embedded in rich looser systems which we call HCG associations. Analysis of the redshift neighborhood of HCGs outside the CfA survey suggests that most HCGs are embedded in more extended physical systems. Rich loose groups extracted from the CfA survey (Ramella et al. (1994)) have physical properties similar to those of the HCG associations. These rich loose groups often contain compact configurations. N-body experiments (Diaferio (1994)) suggest that compact configurations analogous to HCGs form continually during the collapse of rich loose groups. These observational and numerical results suggest that rich loose groups are the birthplace of HCGs.
Ravikumar, V.; Rodrigues, R.P.; Dravid, V.P.
1997-05-01
Transmission high-energy electron holography has been utilized to quantitatively determine the magnitude, sign, and spatial extent of the electrical potential, electric field, as well as the charge and stress field distributions across electrically active grain boundaries (GBs) in polycrystalline SrTiO{sub 3}. The polycrystalline compacts utilized were bulk-doped with Fe and GB-doped with Mn, which is diffused into them under a nonequilibrium situation. The holography results reveal negatively charged GBs with associated positive space-charge, indicating that Mn resides as an acceptor dopant on the Ti site, creating a negative bound charge at the GBs. A large heterogeneity in the electrical activity is observed among various GBs; while some GBs show high Schottky barriers, others have very small barriers. The distribution of the bound charge and the compensating free charge, which together contribute to the formation of GB charge and space-charge, has been estimated. The bound charge experiences an outward stress field due to the force of the electric field on either side of the GB. The height of the double Schottky barrier, the Debye length, as well as the spatial extent of the bound charge and space-charge at the GB are derived from these holography results. The results also provide a quantitative measure of the defect densities as well as of the contribution of the electrostatic stress field to the lattice relaxation at the GBs and yield a point defect model for the GB.
Observational properties of compact groups of galaxies
NASA Technical Reports Server (NTRS)
Hickson, Paul
1990-01-01
Compact groups are small, relatively isolated, systems of galaxies with projected separations comparable to the diameters of the galaxies themselves. Two well-known examples are Stephan's Quintet (Stephan, 1877) and Seyfert's Sextet (Seyfert 1948a,b). In groups such as these, the apparent space density of galaxies approaches 10(exp 6) Mpc(sub -3), denser even than the cores of rich clusters. The apparent unlikeliness of the chance occurrence of such tight groupings lead Ambartsumyan (1958, 1975) to conclude that compact groups must be physically dense systems. This view is supported by clear signs of galaxy interactions that are seen in many groups. Spectroscopic observations reveal that typical relative velocities of galaxies in the groups are comparable to their internal stellar velocities. This should be conducive to strong gravitational interactions - more so than in rich clusters, where galaxy velocities are typically much higher. This suggests that compact groups could be excellent laboratories in which to study galaxy interactions and their effects. Compact groups often contain one or more galaxies whose redshift differs greatly from those of the other group members. If these galaxies are at the same distance as the other members, either entire galaxies are being ejected at high velocities from these groups, or some new physical phenomena must be occurring. If their redshifts are cosmological, we must explain why so many discordant galaxies are found in compact groups. In recent years much progress has been made in addressing these questions. Here, the author discusses the current observational data on compact groups and their implications.
Pipeline charging of coke ovens with a preheated charge
A. V. Karpov; A. V. Khadzhioglo; V. V. Kharasika; V. M. Kuznichenko; G. N. Nikiforov; P. L. Novitskii; P. D. Redka; V. D. Semenenko; V. M. Shcherbina; A. I. Tolstikov
1983-01-01
One method of further development of the coking industry to increase its efficiency is the adoption of the method of charge preheating before coking. However, the tendency of a heated charge to high particulates and gas emission in the charging process necessitates the development of a method of emission free charging of ovens. It was shown to be possible in
Distribution of compact object mergers around galaxies
Tomasz Bulik; Krzysztof Belczynski; Wojciech Zbijewski
1999-03-26
Compact object mergers are one of the currently favored models for the origin of GRBs. The discovery of optical afterglows and identification of the nearest, presumably host, galaxies allows the analysis of the distribution of burst sites with respect to these galaxies. Using a model of stellar binary evolution we synthesize a population of compact binary systems which merge within the Hubble time. We include the kicks in the supernovae explosions and calculate orbits of these binaries in galactic gravitational potentials. We present the resulting distribution of merger sites and discuss the results in the framework of the observed GRB afterglows.
Compact Focal Plane Assembly for Planetary Science
NASA Technical Reports Server (NTRS)
Brown, Ari; Aslam, Shahid; Huang, Wei-Chung; Steptoe-Jackson, Rosalind
2013-01-01
A compact radiometric focal plane assembly (FPA) has been designed in which the filters are individually co-registered over compact thermopile pixels. This allows for construction of an ultralightweight and compact radiometric instrument. The FPA also incorporates micromachined baffles in order to mitigate crosstalk and low-pass filter windows in order to eliminate high-frequency radiation. Compact metal mesh bandpass filters were fabricated for the far infrared (FIR) spectral range (17 to 100 microns), a game-changing technology for future planetary FIR instruments. This fabrication approach allows the dimensions of individual metal mesh filters to be tailored with better than 10- micron precision. In contrast, conventional compact filters employed in recent missions and in near-term instruments consist of large filter sheets manually cut into much smaller pieces, which is a much less precise and much more labor-intensive, expensive, and difficult process. Filter performance was validated by integrating them with thermopile arrays. Demonstration of the FPA will require the integration of two technologies. The first technology is compact, lightweight, robust against cryogenic thermal cycling, and radiation-hard micromachined bandpass filters. They consist of a copper mesh supported on a deep reactive ion-etched silicon frame. This design architecture is advantageous when constructing a lightweight and compact instrument because (1) the frame acts like a jig and facilitates filter integration with the FPA, (2) the frame can be designed so as to maximize the FPA field of view, (3) the frame can be simultaneously used as a baffle for mitigating crosstalk, and (4) micron-scale alignment features can be patterned so as to permit high-precision filter stacking and, consequently, increase the filter bandwidth and sharpen the out-of-band rolloff. The second technology consists of leveraging, from another project, compact and lightweight Bi0.87Sb0.13/Sb arrayed thermopiles. These detectors consist of 30-layer thermopiles deposited in series upon a silicon nitride membrane. At 300 K, the thermopile arrays are highly linear over many orders of magnitude of incident IR power, and have a reported specific detectivity that exceeds the requirements imposed on future mission concepts. The bandpass filter array board is integrated with a thermopile array board by mounting both boards on a machined aluminum jig.
Remote vacuum compaction of compressible hazardous waste
Coyne, M.J.; Fiscus, G.M.; Sammel, A.G.
1998-10-06
A system is described for remote vacuum compaction and containment of low-level radioactive or hazardous waste comprising a vacuum source, a sealable first flexible container, and a sealable outer flexible container for receiving one or more first flexible containers. A method for compacting low level radioactive or hazardous waste materials at the point of generation comprising the steps of sealing the waste in a first flexible container, sealing one or more first containers within an outer flexible container, breaching the integrity of the first containers, evacuating the air from the inner and outer containers, and sealing the outer container shut. 8 figs.
Remote vacuum compaction of compressible hazardous waste
Coyne, M.J.; Fiscus, G.M.; Sammel, A.G.
1996-12-31
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.
Compact Raman Spectrometers Would Detect Hydrogen
NASA Technical Reports Server (NTRS)
Helms, William R.; Adler-Golden, Steven
1993-01-01
Compact Raman spectrometers developed to measure concentrations of hydrogen as low as hundreds of parts per million in air, nitrogen, or other carrier gases. Advantages include speed, dynamic range, and ease of calibration. Design concept incorporates Raman-scattering apparatus into compact instrument of hydrogen leaking into stream of gas or into gas enclosed in small space. Should hydrogen-fueled cars and trucks come into widespread use, instruments used to detect leaks from vehicles and supply equipment, to help prevent explosions. Similar spectrometers developed to detect other gases emitting characteristic Raman spectra.
Compaction by impact of unconsolidated lunar fines
NASA Technical Reports Server (NTRS)
Ahrens, T. J.
1975-01-01
An investigation was conducted concerning the macroscopic irreversible partial compaction of terrestrial or lunar fines. A sample material (70051), assumed to be typical of the fines in the unconsolidated material of the lunar regolith, was used in the experiments. Tests were also carried out with powdered Vacaville basalt. Release adiabate and Hugoniot measurements were conducted. It was found that the dynamic stresses required for irreversible compaction of lunar fines on the moon are significantly lower than the values inferred from the shock recovery experiments conducted by Christie et al. (1973).
Dynamic Compaction Modeling of Porous Silica Powder
NASA Astrophysics Data System (ADS)
Borg, John P.; Schwalbe, Larry; Cogar, John; Chapman, D. J.; Tsembelis, K.; Ward, Aaron; Lloyd, Andrew
2006-07-01
A computational analysis of the dynamic compaction of porous silica is presented and compared with experimental measurements. The experiments were conducted at Cambridge University's one-dimensional flyer plate facility. The experiments shock loaded samples of silica dust of various initial porous densities up to a pressure of 2.25 GPa. The computational simulations utilized a linear Us-Up Hugoniot. The compaction events were modeled with CTH, a 3D Eulerian hydrocode developed at Sandia National Laboratory. Simulated pressures at two test locations are presented and compared with measurements.
A compact time-of-flight mass spectrometer for ion source characterization.
Chen, L; Wan, X; Jin, D Z; Tan, X H; Huang, Z X; Tan, G B
2015-03-01
A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters. PMID:25832275
Jeffrey J. Einerson; Jeffrey A. Phillips; Eric L. Shaber; Scott E. Niedzialek; W. Clay Richardson; Scott G. Nagley
2012-10-01
Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of designed experiments have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel. Results from these experiments are included. The scale-up effort is nearing completion with the process installed and operational using nuclear fuel materials. The process is being certified for manufacture of qualification test fuel compacts for the AGR-5/6/7 experiment at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL).
Differential compaction behaviour of roller compacted granules of clopidogrel bisulphate polymorphs.
Khomane, Kailas S; Bansal, Arvind K
2014-09-10
In the present work, in-die and out-of-die compaction behaviour of dry-granulated powders of clopidogrel bisulphate (CLP) polymorphs, form I and form II, was investigated using a fully instrumented rotary tablet press. Each polymorph was compacted at three different roller pressures [70.3 (S1), 105.5 (S2) and 140.6 (S3)kgf/cm(2)], and obtained granules were characterized for their physico-mechanical properties. Compaction data were analyzed for out-of-die compressibility, tabletability and compactibility profiles, and in-die Heckel, Kawakita and Walker analysis. The roller compacted granules of both forms showed markedly different tabletting behaviour. Roller pressure exhibited a trend on compaction behaviour of form I granules, whereas, in case of form II, the effect was insignificant. Tabletability of the six granule batches follows the order; I_S1>I_S2>I_S3>II_S1?II_S2?II_S3. In case of form I, the reduced tabletability of the granules compacted at higher roller pressure was attributed to the decreased compressibility and plastic deformation. This was confirmed by compressibility plot and various mathematical parameters derived from Heckel (Py), Kawakita (1/b) and Walker (W) equations. The reduced tabletability of form I granules was due to 'granule hardening' during roller compaction. On the other hand, insignificant effect of roller compaction on tabletting behaviour of form II granules was attributed to brittle fragmentation. The extensive fragmentation of granules offered new 'clean' surfaces and higher contact points that negated the effect of granule hardening. PMID:24971694
FABRICATION OF URANIUM OXYCARBIDE KERNELS AND COMPACTS FOR HTR FUEL
Dr. Jeffrey A. Phillips; Eric L. Shaber; Scott G. Nagley
2012-10-01
As part of the program to demonstrate tristructural isotropic (TRISO)-coated fuel for the Next Generation Nuclear Plant (NGNP), Advanced Gas Reactor (AGR) fuel is being irradiation tested in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). This testing has led to improved kernel fabrication techniques, the formation of TRISO fuel particles, and upgrades to the overcoating, compaction, and heat treatment processes. Combined, these improvements provide a fuel manufacturing process that meets the stringent requirements associated with testing in the AGR experimentation program. Researchers at Idaho National Laboratory (INL) are working in conjunction with a team from Babcock and Wilcox (B&W) and Oak Ridge National Laboratory (ORNL) to (a) improve the quality of uranium oxycarbide (UCO) fuel kernels, (b) deposit TRISO layers to produce a fuel that meets or exceeds the standard developed by German researches in the 1980s, and (c) develop a process to overcoat TRISO particles with the same matrix material, but applies it with water using equipment previously and successfully employed in the pharmaceutical industry. A primary goal of this work is to simplify the process, making it more robust and repeatable while relying less on operator technique than prior overcoating efforts. A secondary goal is to improve first-pass yields to greater than 95% through the use of established technology and equipment. In the first test, called “AGR-1,” graphite compacts containing approximately 300,000 coated particles were irradiated from December 2006 to November 2009. The AGR-1 fuel was designed to closely replicate many of the properties of German TRISO-coated particles, thought to be important for good fuel performance. No release of gaseous fission product, indicative of particle coating failure, was detected in the nearly 3-year irradiation to a peak burn up of 19.6% at a time-average temperature of 1038–1121°C. Before fabricating AGR-2 fuel, each fabrication process was improved and changed. Changes to the kernel fabrication process included replacing the carbon black powder feed with a surface-modified carbon slurry and shortening the sintering schedule. AGR-2 TRISO particles were produced in a 6-inch diameter coater using a charge size about 21-times that of the 2-inch diameter coater used to coat AGR-1 particles. The compacting process was changed to increase matrix density and throughput by increasing the temperature and pressure of pressing and using a different type of press. AGR-2 fuel began irradiation in the ATR in late spring 2010.
Searches for Fractionally Charged Particles
Perl, Martin L.; /SLAC; Lee, Eric R.; Loomba, Dinesh; /New Mexico U.
2012-04-12
Since the initial measurements of the electron charge were made a century ago, experimenters have faced the persistent question of the existence of elementary particles with charges that are fractional multiples of the electron charge. In this review, we discuss the results of recent searches for these fractionally charged particles.
Taming Highly Charged Radioisotopes
NASA Astrophysics Data System (ADS)
Chowdhury, Usman; Eberhardt, Benjamin; Jang, Fuluni; Schultz, Brad; Simon, Vanessa; Delheij, Paul; Dilling, Jens; Gwinner, Gerald
2012-10-01
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
Sun, Yipeng; /SLAC
2012-05-11
A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and pre-damping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.
Rincon-Mora, Gabriel A.
1 Abstract-- A novel, accurate, compact, and power efficient Lith- ium-Ion (Li-Ion) battery charger gain linear feedback loops and control a single power MOS device, automatically charging the battery or a dc power source, such as USB sup- plies, on-board batteries, fuel cells, and others, and use
Jiri Kovar; Ondrej Kopacek; Vladimir Karas; Zdenek Stuchlik
2010-05-18
Off-equatorial circular orbits with constant latitudes (halo orbits) of electrically charged particles exist near compact objects. In the previous paper, we discussed this kind of motion and demonstrated the existence of minima of the two-dimensional effective potential which correspond to the stable halo orbits. Here, we relax previous assumptions of the pseudo-Newtonian approach for the gravitational field of the central body and study properties of the halo orbits in detail. Within the general relativistic approach, we carry out our calculations in two cases. Firstly, we examine the case of a rotating magnetic compact star. Assuming that the magnetic field axis and the rotation axis are aligned with each other, we study the orientation of motion along the stable halo orbits. In the poloidal plane, we also discuss shapes of the related effective potential halo lobes where the general off-equatorial motion can be bound. Then we focus on the halo orbits near a Kerr black hole immersed in an asymptotically uniform magnetic field of external origin. We demonstrate that, in both the cases considered, the lobes exhibit two different regimes, namely, one where completely disjoint lobes occur symmetrically above and below the equatorial plane, and another where the lobes are joined across the plane. A possible application of the model concerns the structure of putative circumpulsar discs consisting of dust particles. We suggest that the particles can acquire a small (but non-zero) net electric charge, and this drives them to form the halo lobes.
Conformal anisotropic relativistic charged fluid spheres with a linear equation of state
NASA Astrophysics Data System (ADS)
Esculpi, M.; Alomá, E.
2010-06-01
We obtain two new families of compact solutions for a spherically symmetric distribution of matter consisting of an electrically charged anisotropic fluid sphere joined to the Reissner-Nordstrom static solution through a zero pressure surface. The static inner region also admits a one parameter group of conformal motions. First, to study the effect of the anisotropy in the sense of the pressures of the charged fluid, besides assuming a linear equation of state to hold for the fluid, we consider the tangential pressure p ? to be proportional to the radial pressure p r , the proportionality factor C measuring the grade of anisotropy. We analyze the resulting charge distribution and the features of the obtained family of solutions. These families of solutions reproduce for the value C=1, the conformal isotropic solution for quark stars, previously obtained by Mak and Harko. The second family of solutions is obtained assuming the electrical charge inside the sphere to be a known function of the radial coordinate. The allowed values of the parameters pertained to these solutions are constrained by the physical conditions imposed. We study the effect of anisotropy in the allowed compactness ratios and in the values of the charge. The Glazer’s pulsation equation for isotropic charged spheres is extended to the case of anisotropic and charged fluid spheres in order to study the behavior of the solutions under linear adiabatic radial oscillations. These solutions could model some stage of the evolution of strange quark matter fluid stars.
Holographic Compact Disk Read-Only Memories
NASA Technical Reports Server (NTRS)
Liu, Tsuen-Hsi
1996-01-01
Compact disk read-only memories (CD-ROMs) of proposed type store digital data in volume holograms instead of in surface differentially reflective elements. Holographic CD-ROM consist largely of parts similar to those used in conventional CD-ROMs. However, achieves 10 or more times data-storage capacity and throughput by use of wavelength-multiplexing/volume-hologram scheme.
Compact range for variable-zone measurements
Burnside, Walter D. (Columbus, OH); Rudduck, Roger C. (Columbus, OH); Yu, Jiunn S. (Albuquerque, NM)
1988-01-01
A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector.
Compact, Lightweight Servo-Controllable Brakes
NASA Technical Reports Server (NTRS)
Lovchik, Christopher S.; Townsend, William; Guertin, Jeffrey; Matsuoka, Yoky
2010-01-01
Compact, lightweight servo-controllable brakes capable of high torques are being developed for incorporation into robot joints. A brake of this type is based partly on the capstan effect of tension elements. In a brake of the type under development, a controllable intermediate state of torque is reached through on/off switching at a high frequency.
Simplicial volume of non-compact manifolds
LÃ¶h, Clara
Simplicial volume of non-compact manifolds Clara LÂ¨oh April 2008 Abstract. Degree theorems volume. Clara LÂ¨oh Â· clara.loeh@uni-muenster.de Â· Mathematisches Institut Â· WWU MÂ¨unster Â· Einste- instr, con- nected manifold M with |deg f | 2. Then M = 0. 2 Clara LÂ¨oh Â clara.loeh@uni-muenster.de #12
Workability in forging of powder metallurgy compacts
M. Abdel-Rahman; M. N. El-Sheikh
1995-01-01
The power metallurgy (PM) technique is now applied widely to many industries and materials. To obtain more reliable PM products, many secondary processes are applied to PM preforms. The problem of deformation and fracture of PM preforms still needs a considerable amount of investigation.In this work, the effect of the relative density on the forming limit of PM compacts in
On the cold compaction of powders
N. A. Fleck
1995-01-01
Constitutive models are developed for stage I cold compaction of powders under general loading. Densification is assumed to occur by plastic deformation at the isolated contacts between particles. The shape of the yield surface is found to be sensitive to the cohesive strength between particles and to be less sensitive to the degree of inter-particle friction. An internal state variable
MTI compact electronic meter testing program
O`Rourke, E.L.
1995-12-31
MTI has completed an extensive test program to ensure a new compact electronic gas meter meets all specifications and standards customarily employed by the U.S. gas industry. Thirty (30) test plans were developed to cover all American National Standards Institute (ANSI) performance requirements. (1) The prototype meters have met or exceeded the ANSI B109.1 standards. (2) The prototype meters have demonstrated the feasibility of GRI`s decision to seek a compact meter for early market entry. (3) Several leading U.S. utilities have participated in sponsoring the project and have expressed keen interest in field testing the compact meter. (4) American Meter Company (AMC), the predominant U.S. meter manufacturer, has participated in the sponsorship and testing of the compact meter and has formed a joint venture with Select Corporation to bring the meter to the U.S. and world-wide marketplace. (5) The meter generates the necessary electronic output for either telephonic or radio based automatic meter reading (AMR). The pre-production meters for the North American market are being fabricated currently by AMC. Following their completion, an extensive field test program will take place. Three hundred units will be installed at ten to fifteen utilities and tested for a period of up to one year.
COMPACT WIDEBAND TAG ANTENNA FOR UHF RFID
Myung, Noh-Hoon
COMPACT WIDEBAND TAG ANTENNA FOR UHF RFID Sang Ho Lim, Young Cheol Oh, Ho Lim, and Noh Hoon Myung@kaist.ac.kr Received 21 August 2008 ABSTRACT: A UHF radio frequency identification tag antenna us- ing an inductively.08 , 26.4 mm), wide bandwidth, and simple matching technique between a tag an- tenna and a tag chip
Efficient Discriminative Projections for Compact Binary Descriptors
Fua, Pascal
Efficient Discriminative Projections for Compact Binary Descriptors Tomasz Trzcinski and Vincent processing. This, however, comes at a price of lower recognition performances. To boost these performances Trzcinski, Vincent Lepetit = + + + ...+ w Fig. 1. To compute our binary descriptor, we learn from a training
Compact ultrafast microchannel plate photomultiplier tube
Hidehiro Kume; Takeshi Taguchi; K. Nakatsugawa; K. Ozawa; Seiji Suzuki; Reji G. Samuel; Y. Nishimura; I. Yamazaki
1992-01-01
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
A compact transportable Josephson voltage standard
Hamilton, C.A.; Burroughs, C.J.; Kupferman, S.L.
1996-06-01
The development of a compact, portable 10 V Josephson calibration system is described. Its accuracy is the same as typical laboratory systems and its weight and volume are reduced by more than a factor of three. The new system will replace travelling voltage standards used within several NASA and DOE standards laboratories.
Orbital phase in inspiralling compact binaries
Mátyás Vasúth; Balázs Mikóczi; László Á. Gergely
2007-03-09
We derive the rate of change of the mean motion up to the second post-Newtonian order for inspiralling compact binaries with spin, mass quadrupole and magnetic dipole moments on eccentric orbits. We give this result in terms of orbital elements. We also present the related orbital phase for circular orbits.
The Boston Compact: A Teaching Case.
ERIC Educational Resources Information Center
Farrar, Eleanor
The Boston Compact, signed in September 1982, is a formal agreement between the Boston School Department and members of the business community to collaborate in making new educational and employment opportunities available to the city's high school students. Co-signers agreed to the following: (1) assist in developing private sector initiatives in…
Compact range for variable-zone measurements
Burnside, W.D.; Rudduck, R.C.; Yu, J.S.
1987-02-27
A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector. 2 figs.
Preferential Path Profiling: Compactly Numbering Interesting Paths
Chilimbi, Trishul
Preferential Path Profiling: Compactly Numbering Interesting Paths Kapil Vaswani Indian Institute@microsoft.com Trishul M. Chilimbi Microsoft Research trishulc@microsoft.com Abstract Path profiles provide a more preferential path profiling (PPP), that reduces the overhead of path profiling. PPP leverages the observation
Compact imaging spectrometer utilizing immersed gratings
Lerner, Scott A.
2005-12-20
A compact imaging spectrometer comprising an entrance slit for directing light, lens means for receiving the light, refracting the light, and focusing the light; an immersed diffraction grating that receives the light from the lens means and defracts the light, the immersed diffraction grating directing the detracted light back to the lens means; and a detector that receives the light from the lens means.
Compact continuum brain model for human electroencephalogram
NASA Astrophysics Data System (ADS)
Kim, J. W.; Shin, H.-B.; Robinson, P. A.
2007-12-01
A low-dimensional, compact brain model has recently been developed based on physiologically based mean-field continuum formulation of electric activity of the brain. The essential feature of the new compact model is a second order time-delayed differential equation that has physiologically plausible terms, such as rapid corticocortical feedback and delayed feedback via extracortical pathways. Due to its compact form, the model facilitates insight into complex brain dynamics via standard linear and nonlinear techniques. The model successfully reproduces many features of previous models and experiments. For example, experimentally observed typical rhythms of electroencephalogram (EEG) signals are reproduced in a physiologically plausible parameter region. In the nonlinear regime, onsets of seizures, which often develop into limit cycles, are illustrated by modulating model parameters. It is also shown that a hysteresis can occur when the system has multiple attractors. As a further illustration of this approach, power spectra of the model are fitted to those of sleep EEGs of two subjects (one with apnea, the other with narcolepsy). The model parameters obtained from the fittings show good matches with previous literature. Our results suggest that the compact model can provide a theoretical basis for analyzing complex EEG signals.
Materials needs for compact fusion reactors
Krakowski, R.A.
1983-01-01
The economic prospects for magnetic fusion energy can be dramatically improved if for the same total power output the fusion neutron first-wall (FW) loading and the system power density can be increased by factors of 3 to 5 and 10 to 30, respectively. A number of compact fusion reactor embodiments have been proposed, all of which would operate with increased FW loadings, would use thin (0.5 to 0.6 m) blankets, and would confine quasi-steady-state plasma with resistive, water-cooled copper or aluminum coils. Increased system power density (5 to 15 MWt/m/sup 3/ versus 0.3 to 0.5 MW/m/sup 3/), considerably reduced physical size of the fusion power core (FPC), and appreciably reduced economic leverage exerted by the FPC and associated physics result. The unique materials requirements anticipated for these compact reactors are outlined against the well documented backdrop provided by similar needs for the mainline approaches. Surprisingly, no single materials need that is unique to the compact systems is identified; crucial uncertainties for the compact approaches must also be addressed by the mainline approaches, particularly for in-vacuum components (FWs, limiters, divertors, etc.).
The Blue Compact Dwarf Galaxy IZw18
NASA Astrophysics Data System (ADS)
Musella, I.; Marconi, M.; Fiorentino, G.; Clementini, G.; Aloisi, A.; Annibali, F.; Contreras, R.; Saha, A.; Tosi, M.; van der Marel, R. P.
We present the results obtained for the Blue compact galaxy IZw18 on the basis of ACS HST data obtained from our group. In particular, we discuss the stellar population and the variable stars content of this galaxy to get information about its star formation history and distance.
COMPACT COILED DENUDER FOR ATMOSPHERIC SAMPLING
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...
Non-Compact WZW Conformal Field Theories
Krzysztof Gawedzki
1991-10-31
We discuss non-compact WZW sigma models, especially the ones with symmetric space $H^{\\bf C}/H$ as the target, for $H$ a compact Lie group. They offer examples of non-rational conformal field theories. We remind their relation to the compact WZW models but stress their distinctive features like the continuous spectrum of conformal weights, diverging partition functions and the presence of two types of operators analogous to the local and non-local insertions recently discussed in the Liouville theory. Gauging non-compact abelian subgroups of $H^{\\bf C}$ leads to non-rational coset theories. In particular, gauging one-parameter boosts in the $SL(2,\\bC)/SU(2)$ model gives an alternative, explicitly stable construction of a conformal sigma model with the euclidean 2D black hole target. We compute the (regularized) toroidal partition function and discuss the spectrum of the theory. A comparison is made with more standard approach based on the $U(1)$ coset of the $SU(1,1)$ WZW theory where stability is not evident but where unitarity becomes more transparent.
Energetic particle transport in compact quasiaxisymmetric stellarators
1 Energetic particle transport in compact quasiaxisymmetric stellarators M. H. Redi, H. E. Mynick rates and particle confinement for thermal and neutral beam ions in a small experiment with R=145 cm, B for these configurations suggests that more interesting physics could be explored with an experiment of less constrained
A Global Compact to End Poverty
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
Compact Apparatus For Growth Of Protein Crystals
NASA Technical Reports Server (NTRS)
Carter, Daniel C.; Miller, Teresa Y.
1991-01-01
Compact apparatus proposed specifically for growth of protein crystals in microgravity also used in terrestrial laboratories to initiate and terminate growth at prescribed times automatically. Has few moving parts. Also contains no syringes difficult to clean, load, and unload and introduces contaminant silicon grease into crystallization solution. After growth of crystals terminated, specimens retrieved and transported simply.
BOUNDARIES FOR BANACH SPACES DETERMINE WEAK COMPACTNESS
Boyer, Edmond
BOUNDARIES FOR BANACH SPACES DETERMINE WEAK COMPACTNESS HERMANN PFITZNER Abstract. A boundary for a Banach space is a subset of the dual unit sphere with the property that each element of the Banach space to such a boundary is coarser than the weak topology on the Banach space. Godefroy's Boundary Problem asks whether
Pathway to a Compact SASE FEL Device
Dattoli, G; Petrillo, V; Rau, J V; Sabia, E; Spassovsky, I; Biedron, S G; Einstein, J; Milton, S V
2015-01-01
Newly developed high peak power lasers have opened the possibilities of driving coherent light sources operating with laser plasma accelerated beams and wave undulators. We speculate on the combination of these two concepts and show that the merging of the underlying technologies could lead to new and interesting possibilities to achieve truly compact, coherent radiator devices.
Analytic vortex solutions on compact hyperbolic surfaces
NASA Astrophysics Data System (ADS)
Maldonado, Rafael; Manton, Nicholas S.
2015-06-01
We construct, for the first time, abelian Higgs vortices on certain compact surfaces of constant negative curvature. Such surfaces are represented by a tessellation of the hyperbolic plane by regular polygons. The Higgs field is given implicitly in terms of Schwarz triangle functions and analytic solutions are available for certain highly symmetric configurations.
A compact modular wireless sensor platform
Ari Y. Benbasat; Joseph A. Paradiso
2005-01-01
We have designed and constructed a modular platform for use in compact wireless sensing. This platform is based around a series of circuit boards (or panes), each of which instantiates a specific sensing modality - e.g. inertial sensing, tactile sensing or ambient sensing. As opposed to similar architectures, this system treats the sensor panes as discrete design objects that have
Cofinality in normal, almost compact spaces
Fleissner, William G.; Kulesza, J.; Levy, R.
1991-10-01
A regular space is said to be a NAC space if, given any pair of disjoint closed subsets, one of them is compact. The standard example of a noncompact NAC space is an ordinal space of uncountable cofinality. The coñnality of an arbitrary noncompact...
Compact microwave cavity for hydrogen atomic clock
NASA Technical Reports Server (NTRS)
Zhang, Dejun; Zhang, Yan; Fu, Yigen; Zhang, Yanjun
1992-01-01
A summary is presented that introduces the compact microwave cavity used in the hydrogen atomic clock. Special emphasis is placed on derivation of theoretical calculating equations of main parameters of the microwave cavity. A brief description is given of several methods for discriminating the oscillating modes. Experimental data and respective calculated values are also presented.
Simulation of compact heat exchanger performance
Bengt Sunden
2010-01-01
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