Chao, Alexander Wu; /SLAC
2012-03-01
As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.
Compactification on phase space
NASA Astrophysics Data System (ADS)
Lovelady, Benjamin; Wheeler, James
2016-03-01
A major challenge for string theory is to understand the dimensional reduction required for comparison with the standard model. We propose reducing the dimension of the compactification by interpreting some of the extra dimensions as the energy-momentum portion of a phase-space. Such models naturally arise as generalized quotients of the conformal group called biconformal spaces. By combining the standard Kaluza-Klein approach with such a conformal gauge theory, we may start from the conformal group of an n-dimensional Euclidean space to form a 2n-dimensional quotient manifold with symplectic structure. A pair of involutions leads naturally to two n-dimensional Lorentzian manifolds. For n = 5, this leaves only two extra dimensions, with a countable family of possible compactifications and an SO(5) Yang-Mills field on the fibers. Starting with n=6 leads to 4-dimensional compactification of the phase space. In the latter case, if the two dimensions each from spacetime and momentum space are compactified onto spheres, then there is an SU(2)xSU(2) (left-right symmetric electroweak) field between phase and configuration space and an SO(6) field on the fibers. Such a theory, with minor additional symmetry breaking, could contain all parts of the standard model.
NASA Astrophysics Data System (ADS)
Błaszak, Maciej; Domański, Ziemowit
2012-02-01
This paper develops an alternative formulation of quantum mechanics known as the phase space quantum mechanics or deformation quantization. It is shown that the quantization naturally arises as an appropriate deformation of the classical Hamiltonian mechanics. More precisely, the deformation of the point-wise product of observables to an appropriate noncommutative ⋆-product and the deformation of the Poisson bracket to an appropriate Lie bracket are the key elements in introducing the quantization of classical Hamiltonian systems. The formalism of the phase space quantum mechanics is presented in a very systematic way for the case of any smooth Hamiltonian function and for a very wide class of deformations. The considered class of deformations and the corresponding ⋆-products contains as a special case all deformations which can be found in the literature devoted to the subject of the phase space quantum mechanics. Fundamental properties of ⋆-products of observables, associated with the considered deformations are presented as well. Moreover, a space of states containing all admissible states is introduced, where the admissible states are appropriate pseudo-probability distributions defined on the phase space. It is proved that the space of states is endowed with a structure of a Hilbert algebra with respect to the ⋆-multiplication. The most important result of the paper shows that developed formalism is more fundamental than the axiomatic ordinary quantum mechanics which appears in the presented approach as the intrinsic element of the general formalism. The equivalence of two formulations of quantum mechanics is proved by observing that the Wigner-Moyal transform has all properties of the tensor product. This observation allows writing many previous results found in the literature in a transparent way, from which the equivalence of the two formulations of quantum mechanics follows naturally. In addition, examples of a free particle and a simple harmonic
NASA Astrophysics Data System (ADS)
Sheehan, Daniel Peter
1987-09-01
Experimental measurements are presented of ion phase space evolution in a collisionless magnetoplasma utilizing nonperturbing laser induced fluorescence (LIF) diagnostics. Ion configuration space and velocity space transport, and ion thermodynamic information were derived from the phase space diagrams for the following beam-plasma and obstacle-plasma systems:(UNFORMATTED TABLE OR EQUATION FOLLOWS) OBSTACLE & PLASMA SPECIES qquad disc & quad Ba ^+/e^ qquad disc & quad Ba^+/SF _6^-/e^ BEAM SPECIES & PLASMA SPECIES} qquad Ba^+ & quad Cs^+/e^ qquad Cs^+ & quad Ba^+/e^ qquad Ba^+ & quad Cs^+/SF_6 ^-/e^ qquad e^- & quad Ba^+ /e^ TABLE/EQUATION ENDS The ions were roughly mass symmetric. Plasma systems were reconstructed from multiple discrete Ba(II) ion velocity distributions with spatial, temporal, and velocity resolution of 1 mm^3, 2 musec, and 3 times 1010 cm ^3/sec^3 respectively. Phase space reconstructions indicated resonant ion response to the current-driven electrostatic ion cyclotron wave (EICW) in the case of an electron beam and to the ion cyclotron-cyclotron wave in the case of ion beams. Ion energization was observed in both systems. Local particle kinetic energy densities increase far above thermal levels in the presence of the EICW and ICCW. Time-resolved measurements of the EICW identified phase space particle bunching. The nonlinear evolution of f_{rm i}(x,v,t) was investigated for both beam systems. The near wake of conducting electrically floating disc obstacle was studied. Anomalous cross field diffusion (D_bot > 10 ^4 cm^2/sec) and ion energization were correlated with strong, low-frequency turbulence generated by the obstacle. Ion perpendicular kinetic energy densities doubled over thermal levels in the near wake. Upstream of the obstacle, l ~ 50 lambda_ {rm D}, a collisionless shock was indicated; far downstream, an ion flux peak was observed. Three negative ion plasma (NIP) sources were developed and characterized in the course of research: two
Emittance and Phase Space Exchange
Xiang, Dao; Chao, Alex; /SLAC
2011-08-19
Alternative chicane-type beam lines are proposed for exact emittance exchange between horizontal phase space (x; x{prime}) and longitudinal phase space (z; {delta}). Methods to achieve exact phase space exchanges, i.e. mapping x to z, x{prime} to {delta}, z to x and {delta} to x{prime} are suggested. Methods to mitigate the thick-lens effect of the transverse cavity on emittance exchange are discussed. Some applications of the phase space exchanger and the feasibility of an emittance exchange experiment with the proposed chicane-type beam line at SLAC are discussed.
Phase space quantum mechanics - Direct
Nasiri, S.; Sobouti, Y.; Taati, F.
2006-09-15
Conventional approach to quantum mechanics in phase space (q,p), is to take the operator based quantum mechanics of Schroedinger, or an equivalent, and assign a c-number function in phase space to it. We propose to begin with a higher level of abstraction, in which the independence and the symmetric role of q and p is maintained throughout, and at once arrive at phase space state functions. Upon reduction to the q- or p-space the proposed formalism gives the conventional quantum mechanics, however, with a definite rule for ordering of factors of noncommuting observables. Further conceptual and practical merits of the formalism are demonstrated throughout the text.
Phase microscope imaging in phase space
NASA Astrophysics Data System (ADS)
Sheppard, Colin J. R.; Mehta, Shalin B.
2016-03-01
Imaging in a bright field or phase contrast microscope is partially coherent. We have found that the image can be conveniently considered and modeled in terms of the Wigner distribution function (WDF) of the object transmission. The WDF of the object has a simple physical interpretation for the case of a slowly varying object. Basically, the image intensity is the spatial marginal of the spatial convolution of the object WDF with the phase space imager kernel (PSIkernel), a rotated version of the transmission cross-coefficient. The PSI-kernel can be regarded as a partially-coherent generalization of the point spread function. This approach can be extended to consider the partial coherence of the image itself. In particular, we can consider the mutual intensity, WDF or ambiguity function of the image. It is important to note that the spatial convolution of the object WDF with the PSI-kernel is not a WDF, and not the WDF of the image. The phase space representations of the image have relevance to phase reconstruction methods such as phase space tomography, or the transport of intensity equation approach, and to the three-dimensional image properties.
Quantum phase transition in space
Damski, Bogdan; Zurek, Wojciech H
2008-01-01
A quantum phase transition between the symmetric (polar) phase and the phase with broken symmetry can be induced in a ferromagnetic spin-1 Bose-Einstein condensate in space (rather than in time). We consider such a phase transition and show that the transition region in the vicinity of the critical point exhibits scalings that reflect a compromise between the rate at which the transition is imposed (i.e., the gradient of the control parameter) and the scaling of the divergent healing length in the critical region. Our results suggest a method for the direct measurement of the scaling exponent {nu}.
Phase nucleation in curved space
NASA Astrophysics Data System (ADS)
Gómez, Leopoldo; García, Nicolás; Vitelli, Vincenzo; Lorenzana, José; Daniel, Vega
Nucleation and growth is the dominant relaxation mechanism driving first-order phase transitions. In two-dimensional flat systems, nucleation has been applied to a wide range of problems in physics, chemistry and biology. Here we study nucleation and growth of two-dimensional phases lying on curved surfaces and show that curvature modifies both critical sizes of nuclei and paths towards the equilibrium phase. In curved space, nucleation and growth becomes inherently inhomogeneous and critical nuclei form faster on regions of positive Gaussian curvature. Substrates of varying shape display complex energy landscapes with several geometry-induced local minima, where initially propagating nuclei become stabilized and trapped by the underlying curvature (Gómez, L. R. et al. Phase nucleation in curved space. Nat. Commun. 6:6856 doi: 10.1038/ncomms7856 (2015).).
Longitudinal phase space tomography with space charge
NASA Astrophysics Data System (ADS)
Hancock, S.; Lindroos, M.; Koscielniak, S.
2000-12-01
Tomography is now a very broad topic with a wealth of algorithms for the reconstruction of both qualitative and quantitative images. In an extension in the domain of particle accelerators, one of the simplest algorithms has been modified to take into account the nonlinearity of large-amplitude synchrotron motion. This permits the accurate reconstruction of longitudinal phase space density from one-dimensional bunch profile data. The method is a hybrid one which incorporates particle tracking. Hitherto, a very simple tracking algorithm has been employed because only a brief span of measured profile data is required to build a snapshot of phase space. This is one of the strengths of the method, as tracking for relatively few turns relaxes the precision to which input machine parameters need to be known. The recent addition of longitudinal space charge considerations as an optional refinement of the code is described. Simplicity suggested an approach based on the derivative of bunch shape with the properties of the vacuum chamber parametrized by a single value of distributed reactive impedance and by a geometrical coupling coefficient. This is sufficient to model the dominant collective effects in machines of low to moderate energy. In contrast to simulation codes, binning is not an issue since the profiles to be differentiated are measured ones. The program is written in Fortran 90 with high-performance Fortran extensions for parallel processing. A major effort has been made to identify and remove execution bottlenecks, for example, by reducing floating-point calculations and recoding slow intrinsic functions. A pointerlike mechanism which avoids the problems associated with pointers and parallel processing has been implemented. This is required to handle the large, sparse matrices that the algorithm employs. Results obtained with and without the inclusion of space charge are presented and compared for proton beams in the CERN protron synchrotron booster. Comparisons
A general formalism for phase space calculations
NASA Technical Reports Server (NTRS)
Norbury, John W.; Deutchman, Philip A.; Townsend, Lawrence W.; Cucinotta, Francis A.
1988-01-01
General formulas for calculating the interactions of galactic cosmic rays with target nuclei are presented. Methods for calculating the appropriate normalization volume elements and phase space factors are presented. Particular emphasis is placed on obtaining correct phase space factors for 2-, and 3-body final states. Calculations for both Lorentz-invariant and noninvariant phase space are presented.
Quantum phase-space representation for curved configuration spaces
NASA Astrophysics Data System (ADS)
Gneiting, Clemens; Fischer, Timo; Hornberger, Klaus
2013-12-01
We extend the Wigner-Weyl-Moyal phase-space formulation of quantum mechanics to general curved configuration spaces. The underlying phase space is based on the chosen coordinates of the manifold and their canonically conjugate momenta. The resulting Wigner function displays the axioms of a quasiprobability distribution, and any Weyl-ordered operator gets associated with the corresponding phase-space function, even in the absence of continuous symmetries. The corresponding quantum Liouville equation reduces to the classical curved space Liouville equation in the semiclassical limit. We demonstrate the formalism for a point particle moving on two-dimensional manifolds, such as a paraboloid or the surface of a sphere. The latter clarifies the treatment of compact coordinate spaces, as well as the relation of the presented phase-space representation to symmetry groups of the configuration space.
Mining the Observational Phase Space
NASA Astrophysics Data System (ADS)
Norris, Ray
2012-09-01
Experience has shown that many great discoveries in astronomy have been made, not by testing a hypothesis, but by observing the sky in an innovative way. The necessary conditions for this to take place are (a) a telescope observing an unexplored part of the observational phase space (frequency, resolution, time-domain, area of sky, etc), (b) an intelligent observer who understands the instrument sufficiently well to distinguish between artefact and discovery, (c) a prepared and enthusiastic mind ready to accommodate and interpret a new discovery. Next generation survey telescopes will easily satisfy (a), if only in terms of the numbers of objects surveyed. However, their petabytes of data, and arms-length access, may prevent an observer from satisfying (b) and (c). We can only hope that someone will eventually stumble across any unexpected phenomena in the data. However the impenetrable size of the database implies dark corners that will never be fully explored. Discoveries may remain undiscovered, forever. What is the alternative? Can we harness data-mining techniques to help the intelligent observer search for the unexpected? I believe we can, and indeed we must if we are to reap the full scientific benefit of next-generation survey telescopes.
Quantum Phase Space from Schwinger's Measurement Algebra
NASA Astrophysics Data System (ADS)
Watson, P.; Bracken, A. J.
2014-07-01
Schwinger's algebra of microscopic measurement, with the associated complex field of transformation functions, is shown to provide the foundation for a discrete quantum phase space of known type, equipped with a Wigner function and a star product. Discrete position and momentum variables label points in the phase space, each taking distinct values, where is any chosen prime number. Because of the direct physical interpretation of the measurement symbols, the phase space structure is thereby related to definite experimental configurations.
Phase-space quantization of field theory.
Curtright, T.; Zachos, C.
1999-04-20
In this lecture, a limited introduction of gauge invariance in phase-space is provided, predicated on canonical transformations in quantum phase-space. Exact characteristic trajectories are also specified for the time-propagating Wigner phase-space distribution function: they are especially simple--indeed, classical--for the quantized simple harmonic oscillator. This serves as the underpinning of the field theoretic Wigner functional formulation introduced. Scalar field theory is thus reformulated in terms of distributions in field phase-space. This is a pedagogical selection from work published and reported at the Yukawa Institute Workshop ''Gauge Theory and Integrable Models'', 26-29 January, 1999.
The Way to Phase Space Crystals
NASA Astrophysics Data System (ADS)
Guo, Lingzhen; Michael, Marthaler; Schön, Gerd
A novel way to create a band structure of the quasienergy spectrum for driven systems is proposed based on the discrete symmetry in phase space. The system, e.g., an ion or ultracold atom trapped in a potential, shows no spatial periodicity, but it is driven by a time-dependent field. Under rotating wave approximation, the system can produce a periodic lattice structure in phase space. The band structure in quasienergy arises as a consequence of the n-fold discrete periodicity in phase space induced by this driving field. We propose explicit models to realize such a phase space crystal and analyze its band structure in the frame of a tightbinding approximation. The phase space lattice differs fundamentally from a lattice in real space, because its coordinate system, i.e., phase space, has a noncommutative geometry. The phase space crystal opens new ways to engineer energy band structures, with the added advantage that its properties can be changed in situ by tuning the driving field's parameters. Carl-Zeiss Stiftung.
RADON reconstruction in longitudinal phase space
Mane, V.; Peggs, S.; Wei, J.
1997-07-01
Longitudinal particle motion in circular accelerators is typically monitoring by one dimensional (1-D) profiles. Adiabatic particle motion in two dimensional (2-D) phase space can be reconstructed with tomographic techniques, using 1-D profiles. A computer program RADON has been developed in C++ to process digitized mountain range data and perform the phase space reconstruction for the AGS, and later for Relativistic Heavy Ion Collider (RHIC).
NASA Astrophysics Data System (ADS)
Frey, Randy W.; Rawlins, Greg; Zepkin, Neil; Bohlin, John
1989-03-01
A pseudo-ranging laser radar (PRLADAR) concept is proposed to provide extended range capability to tracking LADAR systems meeting the long-range requirements of SDI mission scenarios such as the SIE midcourse program. The project will investigate the payoff of several transmitter modulation techniques and a feasibility demonstration using a breadboard implementation of a new receiver concept called the Phase Multiplexed Correlator (PMC) will be accomplished. The PRLADAR concept has specific application to spaceborne LADAR tracking missions where increased CNR/SNR performance gained by the proposed technique may reduce the laser power and/or optical aperture requirement for a given mission. The reduction in power/aperture has similar cost reduction advantages in commercial ranging applications. A successful Phase 1 program will lay the groundwork for a quick reaction upgrade to the AMOS/LASE system in support of near term SIE measurement objectives.
Liquid crystal phase shifters for space applications
NASA Astrophysics Data System (ADS)
Woehrle, Christopher D.
Space communication satellites have historically relied heavily on high gain gimbal dish antennas for performing communications. Reflector dish antennas lack flexibility in anti-jamming capabilities, and they tend to have a high risk associated to them given the need for mechanical mechanisms to beam steer. In recent years, a great amount of investment has been made into phased array antenna technologies. Phased arrays offer increased signal flexibility at reduced financial cost and in system risk. The problem with traditional phased arrays is the significant program cost and overall complexity added to the satellite by integrating antenna elements that require many dedicated components to properly perform adaptive beam steering. Several unique methods have been proposed to address the issues that plague traditional phase shifters slated for space applications. Proposed approaches range from complex mechanical switches (MEMS) and ferroelectric devices to more robust molecular changes. Nematic liquid crystals offer adaptive beam steering capabilities that traditional phased arrays have; however, with the added benefit of reduced system cost, complexity, and increased resilience to space environmental factors. The objective of the work presented is to investigate the feasibility of using nematic liquid crystals as a means of phase shifting individual phased array elements slated for space applications. Significant attention is paid to the survivability and performance of liquid crystal and associated materials in the space environment. Performance regarding thermal extremes and interactions with charged particles are the primary factors addressed.
Single phase space laundry development
NASA Technical Reports Server (NTRS)
Colombo, Gerald V.; Putnam, David F.; Lunsford, Teddie D.; Streech, Neil D.; Wheeler, Richard R., Jr.; Reimers, Harold
1993-01-01
This paper describes a newly designed, 2.7 Kg (6 pound) capacity, laundry machine called the Single Phase Laundry (SPSL). The machine was designed to wash and dry crew clothing in a micro-gravity environment. A prototype unit was fabricated for NASA-JSC under a Small Business Innovated Research (SBIR) contract extending from September 1990 to January 1993. The unit employs liquid jet agitation, microwave vacuum drying, and air jet tumbling, which was perfected by KC-135 zero-g flight testing. Operation is completely automated except for loading and unloading clothes. The unit uses about 20 percent less power than a conventional household appliance.
Beam Tomography in Longitudinal Phase Space
NASA Astrophysics Data System (ADS)
Mane, V.; Wei, J.; Peggs, S.
1997-05-01
Longitudinal particle motion in circular accelerators is typically monitored by one dimensional (1-D) profiles. Adiabatic particle motion in 2-D phase space can be reconstructed with tomographic techniques, using 1-D profiles. In this paper, we discuss a filtered backprojection algorithm, with a high pass ramp or Hann filter, for phase space reconstruction. The algorithm uses several projections of the beam at equally spaced angles over half a synchrotron period. A computer program RADON has been developed to process digitized mountain range data and do the phase space reconstruction for the AGS, and later for Relativistic Heavy Ion Collider (RHIC). Analysis has been performed to determine the sensitivity to machine parameters and data acquisition errors. During the Sextant test of RHIC in early 1997, this program has been successfully employed to reconstruct the motion of Au^77+ beam in the AGS.
Space Phase III - The commercial era dawns
NASA Technical Reports Server (NTRS)
Allnutt, R. F.
1983-01-01
After the 'Phase I' of space activities, the period bounded by Sputnik and Apollo, 'Phase II', has been entered, a phase in which concerns over the use and the protection of space assets which support national security predominate. However, it is only when the commercial motive becomes prominent that human activity in new regions truly prospers and enters periods of exponential growth. It is believed that there are increasing signs that such a period, called 'Space Phase III', may be coming soon. A description is presented of developments and results upon which this conclusion is based. Since 1980, there have been three developments of great importance for the future of space activities. Six highly successful flights have demonstrated that the Space Shuttle concept works. A series of Soviet missions are related to the emergence of a capability to construct and service modular space stations. Successful tests of the European Ariane 1 indicate an end to U.S. monopoly with respect to the provision of launch services to the Western World.
Neutral line chaos and phase space structure
NASA Technical Reports Server (NTRS)
Burkhart, Grant R.; Speiser, Theodore W.; Martin, Richard F., Jr.; Dusenbery, Paul B.
1991-01-01
Phase space structure and chaos near a neutral line are studied with numerical surface-of-section (SOS) techniques and analytic methods. Results are presented for a linear neutral line model with zero crosstail electric field. It was found that particle motion can be divided into three regimes dependening on the value of the conserved canonical momentum, Py, and the conserved Hamiltonian, h. The phase space structure, using Poincare SOS plots, is highly sensitive to bn = Bn/B0 variations, but not to h variations. It is verified that the slow motion preserves the action, Jz, as evaluated by Sonnerup (1971), when the period of the fast motion is smaller than the time scale of the slow motion. Results show that the phase space structure and particle chaos depend sensitively upon Py and bn, but are independent of h.
Noether symmetries in the phase space
NASA Astrophysics Data System (ADS)
Díaz, Bogar; Galindo-Linares, Elizabeth; Ramírez-Romero, Cupatitzio; Silva-Ortigoza, Gilberto; Suárez-Xique, Román; Torres del Castillo, Gerardo F.; Velázquez, Mercedes
2014-09-01
The constants of motion of a mechanical system with a finite number of degrees of freedom are related to the variational symmetries of a Lagrangian constructed from the Hamiltonian of the original system. The configuration space for this Lagrangian is the phase space of the original system. The symmetries considered in this manner include transformations of the time and may not be canonical in the standard sense.
Space Fence PDR Concept Development Phase
NASA Astrophysics Data System (ADS)
Haines, L.; Phu, P.
2011-09-01
The Space Fence, a major Air Force acquisition program, will become the dominant low-earth orbit uncued sensor in the space surveillance network (SSN). Its primary objective is to provide a 24/7 un-cued capability to find, fix, and track small objects in low earth orbit to include emerging and evolving threats, as well as the rapidly growing population of orbital debris. Composed of up to two geographically dispersed large-scale S-band phased array radars, this new system-of-systems concept will provide comprehensive Space Situational Awareness through net-centric operations and integrated decision support. Additionally, this program will facilitate cost saving force structure changes in the SSN, specifically including the decommissioning of very-high frequency VHF Air Force Space Surveillance System (AFSSS). The Space Fence Program Office entered a Preliminary Design Review (PDR) concept development phase in January 2011 to achieve the delivery of the Initial Operational Capability (IOC) expected in FY17. Two contractors were awarded to perform preliminary system design, conduct radar performance analyses and evaluations, and develop a functional PDR radar system prototype. The key objectives for the Phase A PDR effort are to reduce Space Fence total program technical, cost, schedule, and performance risk. The overall program objective is to achieve a preliminary design that demonstrates sufficient technical and manufacturing maturity and that represents a low risk, affordable approach to meet the Space Fence Technical Requirements Document (TRD) requirements for the final development and production phase to begin in 3QFY12. This paper provides an overview of the revised Space Fence program acquisition strategy for the Phase-A PDR phase to IOC, the overall program milestones and major technical efforts. In addition, the key system trade studies and modeling/simulation efforts undertaken during the System Design Requirement (SDR) phase to address and mitigate
Phase-space foundations of electron holography
NASA Astrophysics Data System (ADS)
Lubk, A.; Röder, F.
2015-09-01
We present a unified formalism for describing various forms of electron holography in quantum mechanical phase space including their extensions to quantum-state reconstructions. The phase-space perspective allows for taking into account partial coherence as well as the quantum mechanical detection process typically hampering the unique reconstruction of a wave function. We elaborate on the limitations imposed by the electron optical elements of the transmission electron microscope as well as the scattering at the target. The results provide the basis for vastly extending the scope of electron holographic techniques towards analyzing partially coherent signals such as inelastically scattered electrons or electron pulses used in ultrafast transmission electron microscopy.
Phase-space contraction and quantum operations
Garcia-Mata, Ignacio; Spina, Maria Elena; Saraceno, Marcos; Carlo, Gabriel
2005-12-15
We give a criterion to differentiate between dissipative and diffusive quantum operations. It is based on the classical idea that dissipative processes contract volumes in phase space. We define a quantity that can be regarded as 'quantum phase space contraction rate' and which is related to a fundamental property of quantum channels: nonunitality. We relate it to other properties of the channel and also show a simple example of dissipative noise composed with a chaotic map. The emergence of attractor-like structures is displayed.
Positive phase space distributions and uncertainty relations
NASA Technical Reports Server (NTRS)
Kruger, Jan
1993-01-01
In contrast to a widespread belief, Wigner's theorem allows the construction of true joint probabilities in phase space for distributions describing the object system as well as for distributions depending on the measurement apparatus. The fundamental role of Heisenberg's uncertainty relations in Schroedinger form (including correlations) is pointed out for these two possible interpretations of joint probability distributions. Hence, in order that a multivariate normal probability distribution in phase space may correspond to a Wigner distribution of a pure or a mixed state, it is necessary and sufficient that Heisenberg's uncertainty relation in Schroedinger form should be satisfied.
Particle emission from covariant phase space
Bambah, B.A. )
1992-12-01
Using Lorentz-covariant sources, we calculate the multiplicity distribution of {ital n} pair correlated particles emerging from a Lorentz-covariant phase-space volume. We use the Kim-Wigner formalism and identify these sources as the squeezed states of a relativistic harmonic oscillator. The applications of this to multiplicity distributions in particle physics is discussed.
Characterizing maximally singular phase-space distributions
NASA Astrophysics Data System (ADS)
Sperling, J.
2016-07-01
Phase-space distributions are widely applied in quantum optics to access the nonclassical features of radiations fields. In particular, the inability to interpret the Glauber-Sudarshan distribution in terms of a classical probability density is the fundamental benchmark for quantum light. However, this phase-space distribution cannot be directly reconstructed for arbitrary states, because of its singular behavior. In this work, we perform a characterization of the Glauber-Sudarshan representation in terms of distribution theory. We address important features of such distributions: (i) the maximal degree of their singularities is studied, (ii) the ambiguity of representation is shown, and (iii) their dual space for nonclassicality tests is specified. In this view, we reconsider the methods for regularizing the Glauber-Sudarshan distribution for verifying its nonclassicality. This treatment is supported with comprehensive examples and counterexamples.
A space-fed phased array for surveillance from space
NASA Astrophysics Data System (ADS)
Hightower, Charles H.; Wong, Sam H.; Perkons, Alfred R.; Igwe, Christian I.
1991-05-01
A space-fed radar antenna called a venetian blind is proposed for all-weather wide-area surveillance from space. Radar requirements for tasked and untasked operation are discussed, and the process of selecting the venetian blind concept, which can support both, is described. In its untasked form (essentially a space-fed passive lens), it achieves off-axis squint angles of many beamwidths with negligible performance degradation. It is inherently insensitive to mechanical distortion and is a first step in the evolution to the more complex tasked system antenna. The antenna lens consists of easily manufactured slats with microstrip dipole radiating elements and matching networks on a dielectric substrate. Phase control is achieved with low-loss delay lines in the passive lens or active transmit/receive modules if electronic scan is desired.
Space market model development project, phase 3
NASA Technical Reports Server (NTRS)
Bishop, Peter C.; Hamel, Gary P.
1989-01-01
The results of a research project investigating information needs for space commercialization is described. The Space Market Model Development Project (SMMDP) was designed to help NASA identify the information needs of the business community and to explore means to meet those needs. The activity of the SMMDP is reviewed and a report of its operation via three sections is presented. The first part contains a brief historical review of the project since inception. The next part reports results of Phase 3, the most recent stage of activity. Finally, overall conclusions and observations based on the SMMDP research results are presented.
Rockstar: Phase-space halo finder
NASA Astrophysics Data System (ADS)
Behroozi, Peter; Wechsler, Risa; Wu, Hao-Yi
2012-10-01
Rockstar (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement) identifies dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure. Our method is massively parallel (up to 10^5 CPUs) and runs on the largest current simulations (>10^10 particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). Rockstar offers significant improvement in substructure recovery as compared to several other halo finders.
Stratakis, D.; Kishek, R. A.; Bernal, S.; Walter, M.; Haber, I.; Fiorito, R.; Thangaraj, J. C. T.; Quinn, B.; Reiser, M.; O'Shea, P. G.; Li, H.
2006-11-27
In order to understand the charged particle dynamics, e.g. the halo formation, emittance growth, x-y energy transfer and coupling, knowledge of the actual phase space is needed. Other the past decade there is an increasing number of articles who use tomography to map the beam phase space and measure the beam emittance. These studies where performed at high energy facilities where the effect of space charge was neglible and therefore not considered in the analysis. This work extends the tomography technique to beams with space charge. In order to simplify the analysis linear forces where assumed. By carefully modeling the tomography process using the particle-in-cell code WARP we test the validity of our assumptions and the accuracy of the reconstructed phase space. Finally, we report experimental results of phase space mapping at the University of Maryland Electron Ring (UMER) using tomography.
Thermophotovoltaic space power system, phase 3
NASA Technical Reports Server (NTRS)
Horne, W. E.; Lancaster, C.
1987-01-01
Work performed on a research and development program to establish the feasibility of a solar thermophotovoltaic space power generation concept was summarized. The program was multiphased. The earlier work is summarized and the work on the current phase is detailed as it pertains to and extends the earlier work. Much of the experimental hardware and materials development was performed on the internal program. Experimental measurements and data evaluation were performed on the contracted effort. The objectives of the most recent phase were: to examine the thermal control design in order to optimize it for lightweight and low cost; to examine the concentrator optics in an attempt to relieve pointing accuracy requirements to + or - 2 degrees about the optical axis; and to use the results of the thermal and optical studies to synthesize a solar thermophotovoltaic (STPV) module design that is optimized for space application.
Noncanonical phase-space noncommutative black holes
NASA Astrophysics Data System (ADS)
Bastos, Catarina; Bertolami, Orfeu; Dias, Nuno Costa; Prata, Joa~o. Nuno
2012-07-01
In this contribution we present a noncanonical phase-space noncommutative (NC) extension of a Kantowski Sachs (KS) cosmological model to describe the interior of a Schwarzschild black hole (BH). We evaluate the thermodynamical quantities inside this NC Schwarzschild BH and compare with the well known quantities. We find that for a NCBH the temperature and entropy have the same mass dependence as the Hawking quantities for a Schwarzschild BH.
Analytical satellite theory in extended phase space
NASA Technical Reports Server (NTRS)
Bond, V.; Broucke, R.
1980-01-01
It is noted that a satellite theory, based on extended phase space and on the true anomaly, was introduced by Scheifele (1970). In the present paper a simple canonical transformation is shown that makes the transition from the classical Delaunay elements to the Scheifele variables. It is stressed that neither spherical coordinates nor Hamilton-Jacobi theory is used. Finally, attention is given to the meaning of the new variables, especially the use of the true anomaly as one of the variables.
Chirp-driven giant phase space vortices
NASA Astrophysics Data System (ADS)
Trivedi, Pallavi; Ganesh, Rajaraman
2016-06-01
In a collisionless, unbounded, one-dimensional plasma, modelled using periodic boundary conditions, formation of steady state phase space coherent structures or phase space vortices (PSV) is investigated. Using a high resolution one-dimensional Vlasov-Poisson solver based on piecewise-parabolic advection scheme, the formation of giant PSV is addressed numerically. For an infinitesimal external drive amplitude and wavenumber k, we demonstrate the existence of a window of chirped external drive frequency that leads to the formation of giant PSV. The linear, small amplitude, external drive, when chirped, is shown to couple effectively to the plasma and increase both streaming of "untrapped" and "trapped" particle fraction. The steady state attained after the external drive is turned off and is shown to lead to a giant PSV with multiple extrema and phase velocities, with excess density fraction, defined as the deviation from the Maxwellian background, Δ n / n 0 ≃ 20 % - 25 % . It is shown that the process depends on the chirp time duration Δt. The excess density fraction Δn/n0, which contains both trapped and untrapped particle contribution, is also seen to scale with Δt, only inhibited by the gradient of the distribution in velocity space. Both single step drive and multistep chirp processes are shown to lead to steady state giant PSV, with multiple extrema due to embedded holes and clumps, long after the external drive is turned off.
Formation of phase space holes and clumps.
Lilley, M K; Nyqvist, R M
2014-04-18
It is shown that the formation of phase space holes and clumps in kinetically driven, dissipative systems is not restricted to the near threshold regime, as previously reported and widely believed. Specifically, we observe hole-clump generation from the edges of an unmodulated phase space plateau, created via excitation, phase mixing and subsequent dissipative decay of a linearly unstable bulk plasma mode in the electrostatic bump-on-tail model. This has now allowed us to elucidate the underlying physics of the hole-clump formation process for the first time. Holes and clumps develop from negative energy waves that arise due to the sharp gradients at the interface between the plateau and the nearly unperturbed, ambient distribution and destabilize in the presence of dissipation in the bulk plasma. We confirm this picture by demonstrating that the formation of such nonlinear structures in general does not rely on a "seed" wave, only on the ability of the system to generate a plateau. In addition, we observe repetitive cycles of plateau generation and erosion, the latter due to hole-clump formation and detachment, which appear to be insensitive to initial conditions and can persist for a long time. We present an intuitive discussion of why this continual regeneration occurs. PMID:24785043
Phase change water processing for Space Station
NASA Technical Reports Server (NTRS)
Zdankiewicz, E. M.; Price, D. F.
1985-01-01
The use of a vapor compression distillation subsystem (VCDS) for water recovery on the Space Station is analyzed. The self-contained automated system can process waste water at a rate of 32.6 kg/day and requires only 115 W of electric power. The improvements in the mechanical components of VCDS are studied. The operation of VCDS in the normal mode is examined. The VCDS preprototype is evaluated based on water quality, water production rate, and specific energy. The relation between water production rate and fluids pump speed is investigated; it is concluded that a variable speed fluids pump will optimize water production. Components development and testing currently being conducted are described. The properties and operation of the proposed phase change water processing system for the Space Station, based on vapor compression distillation, are examined.
Weak values and the quantum phase space
Lobo, A. C.; Ribeiro, C. A.
2009-07-15
We address the issue of how to properly treat, and in a more general setting, the concept of a weak value of a weak measurement in quantum mechanics. We show that for this purpose, one must take in account the effects of the measuring process on the entire phase space of the measuring system. By using coherent states, we go a step further than Jozsa in a recent paper and we present an example where the result of the measurement is symmetrical in the position and momentum observables and seems to be much better suited for quantum optical implementation.
Optical image encryption in phase space
NASA Astrophysics Data System (ADS)
Liu, Jun; Xu, Xiaobin; Situ, Guohai; Wu, Quanying
2014-11-01
In the field of optical information security, the research of double random phase encoding is becoming deeper with each passing day, however the encryption system is linear, and the dependencies between plaintext and ciphertext is not complicated, with leaving a great hidden danger to the security of the encryption system. In this paper, we encrypted the higher dimensional Wigner distribution function of low dimensional plaintext by using the bilinear property of Wigner distribution function. Computer simulation results show that this method can not only enlarge the key space, but also break through the linear characteristic of the traditional optical encryption technology. So it can significantly improve the safety of the encryption system.
Hermitian geometry of 6-dimensional submanifolds of the Cayley algebra
Banaru, M B
2002-06-30
Orientable 6-dimensional submanifolds (of general type) of the Cayley algebra are investigated on which the 3-fold vector cross products in the octave algebra induce a Hermitian structure. It is shown that such submanifolds of the Cayley algebra are minimal, non-compact, and para-Kaehler, their holomorphic bisectional curvature is positive and vanishes only at the geodesic points. It is also proved that cosymplectic hypersurfaces of 6-dimensional Hermitian submanifolds of the octave algebra are ruled. A simple test for the minimality of such surfaces is obtained. It is shown that 6-dimensional submanifolds of the Cayley algebra satisfying the axiom of g-cosymplectic hypersurfaces are Kaehler manifolds.
Space Transportation Engine Program (STEP), phase B
NASA Technical Reports Server (NTRS)
1990-01-01
The Space Transportation Engine Program (STEP) Phase 2 effort includes preliminary design and activities plan preparation that will allow smooth and time transition into a Prototype Phase and then into Phases 3, 4, and 5. A Concurrent Engineering approach using Total Quality Management (TQM) techniques, is being applied to define an oxygen-hydrogen engine. The baseline from Phase 1/1' studies was used as a point of departure for trade studies and analyses. Existing STME system models are being enhanced as more detailed module/component characteristics are determined. Preliminary designs for the open expander, closed expander, and gas generator cycles were prepared, and recommendations for cycle selection made at the Design Concept Review (DCR). As a result of July '90 DCR, and information subsequently supplied to the Technical Review Team, a gas generator cycle was selected. Results of the various Advanced Development Programs (ADP's) for the Advanced Launch Systems (ALS) were contributive to this effort. An active vehicle integration effort is supplying the NASA, Air Force, and vehicle contractors with engine parameters and data, and flowing down appropriate vehicle requirements. Engine design and analysis trade studies are being documented in a data base that was developed and is being used to organize information. To date, seventy four trade studies were input to the data base.
Phase space representation of quantum dynamics
Polkovnikov, Anatoli
2010-08-15
We discuss a phase space representation of quantum dynamics of systems with many degrees of freedom. This representation is based on a perturbative expansion in quantum fluctuations around one of the classical limits. We explicitly analyze expansions around three such limits: (i) corpuscular or Newtonian limit in the coordinate-momentum representation, (ii) wave or Gross-Pitaevskii limit for interacting bosons in the coherent state representation, and (iii) Bloch limit for the spin systems. We discuss both the semiclassical (truncated Wigner) approximation and further quantum corrections appearing in the form of either stochastic quantum jumps along the classical trajectories or the nonlinear response to such jumps. We also discuss how quantum jumps naturally emerge in the analysis of non-equal time correlation functions. This representation of quantum dynamics is closely related to the phase space methods based on the Wigner-Weyl quantization and to the Keldysh technique. We show how such concepts as the Wigner function, Weyl symbol, Moyal product, Bopp operators, and others automatically emerge from the Feynmann's path integral representation of the evolution in the Heisenberg representation. We illustrate the applicability of this expansion with various examples mostly in the context of cold atom systems including sine-Gordon model, one- and two-dimensional Bose-Hubbard model, Dicke model and others.
Quantum mechanics on phase space and teleportation
NASA Astrophysics Data System (ADS)
Messamah, Juba; Schroeck, Franklin E.; Hachemane, Mahmoud; Smida, Abdallah; Hamici, Amel H.
2015-03-01
The formalism of quantum mechanics on phase space is used to describe the standard protocol of quantum teleportation with continuous variables in order to partially investigate the interplay between this formalism and quantum information. Instead of the Wigner quasi-probability distributions used in the standard protocol, we use positive definite true probability densities which account for unsharp measurements through a proper wave function representing a non-ideal quantum measuring device. This is based on a result of Schroeck and may be taken on any relativistic or nonrelativistic phase space. The obtained formula is similar to a known formula in quantum optics, but contains the effect of the measuring device. It has been applied in three cases. In the first case, the two measuring devices, corresponding to the two entangled parts shared by Alice and Bob, are not entangled and described by two identical Gaussian wave functions with respect to the Heisenberg group. They lead to a probability density identical to the function which is analyzed and compared with the Wigner formalism. A new expression of the teleportation fidelity for a coherent state in terms of the quadrature variances is obtained. In the second case, these two measuring devices are entangled in a two-mode squeezed vacuum state. In the third case, two Gaussian states are combined in an entangled squeezed state. The overall observation is that the state of the measuring devices shared by Alice and Bob influences the fidelity of teleportation through their unsharpness and entanglement.
Uncertainty relations for general phase spaces
NASA Astrophysics Data System (ADS)
Werner, Reinhard F.
2016-04-01
We describe a setup for obtaining uncertainty relations for arbitrary pairs of observables related by a Fourier transform. The physical examples discussed here are the standard position and momentum, number and angle, finite qudit systems, and strings of qubits for quantum information applications. The uncertainty relations allow for an arbitrary choice of metric for the outcome distance, and the choice of an exponent distinguishing, e.g., absolute and root mean square deviations. The emphasis of this article is on developing a unified treatment, in which one observable takes on values in an arbitrary locally compact Abelian group and the other in the dual group. In all cases, the phase space symmetry implies the equality of measurement and preparation uncertainty bounds. There is also a straightforward method for determining the optimal bounds.
Reanalysis of relativistic electron phase space density
NASA Astrophysics Data System (ADS)
Shprits, Yuri; Chen, Yue; Kondrashov, Dmitri
In this study we perform a reanalysis of the sparse relativistic electron data using a relatively simple one-dimensional radial diffusion model and a Kalman filtering approach. The results of the reanalysis clearly show pronounced peaks in the electron phase space density (PSD), which can not be explained by the variations in the outer boundary, and can only be produced by a local acceleration processes. The location of the innovation vector shows that local acceleration is most efficient at L* = 5.5. To verify that our results are not affected by the limitations of the satellite orbit and coverage, we performed an "identical twin" experiments with synthetic data specified only at the locations for which CRRES observations are available. Our results indicate that the model with data assimilation can accurately reproduce the underlying structure of the PSD even when data is sparse.
Space-time geometry of topological phases
Burnell, F.J.; Simon, Steven H.
2010-11-15
The 2 + 1 dimensional lattice models of Levin and Wen (2005) provide the most general known microscopic construction of topological phases of matter. Based heavily on the mathematical structure of category theory, many of the special properties of these models are not obvious. In the current paper, we present a geometrical space-time picture of the partition function of the Levin-Wen models which can be described as doubles (two copies with opposite chiralities) of underlying anyon theories. Our space-time picture describes the partition function as a knot invariant of a complicated link, where both the lattice variables of the microscopic Levin-Wen model and the terms of the Hamiltonian are represented as labeled strings of this link. This complicated link, previously studied in the mathematical literature, and known as Chain-Mail, can be related directly to known topological invariants of 3-manifolds such as the so-called Turaev-Viro invariant and the Witten-Reshitikhin-Turaev invariant. We further consider quasi-particle excitations of the Levin-Wen models and we see how they can be understood by adding additional strings to the Chain-Mail link representing quasi-particle world-lines. Our construction gives particularly important new insight into how a doubled theory arises from these microscopic models.
Space market model development project, phase 2
NASA Technical Reports Server (NTRS)
Bishop, Peter C.
1988-01-01
The results of the prototype operations of the Space Business Information Center are presented. A clearinghouse for space business information for members of the U.S. space industry composed of public, private, and academic sectors was conducted. Behavioral and evaluation statistics were recorded from the clearinghouse and the conclusions from these statistics are presented. Business guidebooks on major markets in space business are discussed. Proprietary research and briefings for firms and agencies in the space industry are also discussed.
Stabilizer information inequalities from phase space distributions
NASA Astrophysics Data System (ADS)
Gross, David; Walter, Michael
2013-08-01
The Shannon entropy of a collection of random variables is subject to a number of constraints, the best-known examples being monotonicity and strong subadditivity. It remains an open question to decide which of these "laws of information theory" are also respected by the von Neumann entropy of many-body quantum states. In this article, we consider a toy version of this difficult problem by analyzing the von Neumann entropy of stabilizer states. We find that the von Neumann entropy of stabilizer states satisfies all balanced information inequalities that hold in the classical case. Our argument is built on the fact that stabilizer states have a classical model, provided by the discrete Wigner function: The phase-space entropy of the Wigner function corresponds directly to the von Neumann entropy of the state, which allows us to reduce to the classical case. Our result has a natural counterpart for multi-mode Gaussian states, which sheds some light on the general properties of the construction. We also discuss the relation of our results to recent work by Linden, Ruskai, and Winter ["The quantum entropy cone of stabiliser states," e-print arXiv:1302.5453].
Constructing Phase Space Distributions within the Heliosheath
NASA Astrophysics Data System (ADS)
Roelof, E. C.
2014-12-01
The key function in the description of the dynamics of the heliosheath (HS) is the phase space distribution (PSD) of the protons, i.e., how the interaction between the thermal and non-thermal (heated pick-up) proton populations evolves from the termination shock to the heliopause (HP) in this high-beta plasma. Voyager 1 found the heliopause to be essentially a (compound) magnetic separatrix, because the intensity of the non-thermal particle population became undetectably small beyond the HP, whereas the anisotropy characteristics of the galactic cosmic rays were consistent with no re-entry of the magnetic field lines into the HS (at either end). This paper attempts to synthesize in situ observations from Voyagers 1 and 2 (thermal plasma, magnetic field, energetic ions, and cosmic rays) with global ENA images from IBEX and Cassini/INCA into a self-consistent representation of the PSD within the noseward HS from thermal energies to several MeV/nuc. The interpretation of the ENA images requires assumptions on the global behavior of the bulk plasma flow throughout the HS that are self-consistent with all the available data (e.g., the spatial and energy dependence of the IBEX ribbon), because the Compton-Getting effects produced by the flows strongly affect the intensities (and thereby the partial densities and pressures) inferred from the ENA images.
Overview of Phase Space Manipulations of Relativistic Electron Beams
Xiang, Dao; /SLAC
2012-08-31
Phase space manipulation is a process to rearrange beam's distribution in 6-D phase space. In this paper, we give an overview of the techniques for tailoring beam distribution in 2D, 4D, and 6D phase space to meet the requirements of various applications. These techniques become a new focus of accelerator physics R&D and very likely these advanced concepts will open up new opportunities in advanced accelerators and the science enabled by them.
Space shuttle phase B study plan
NASA Technical Reports Server (NTRS)
Hello, B.
1971-01-01
Phase B emphasis was directed toward development of data which would facilitate selection of the booster concept, and main propulsion system for the orbiter. A shuttle system is also defined which will form the baseline for Phase C program activities.
Space Shuttle aerothermodynamic data report, phase C
NASA Technical Reports Server (NTRS)
1985-01-01
Space shuttle aerothermodynamic data, collected from a continuing series of wind tunnel tests, are permanently stored with the Data Management Services (DMS) system. Information pertaining to current baseline configuration definition is also stored. Documentation of DMS processed data arranged sequentially and by space shuttle configuration are included. An up-to-date record of all applicable aerothermodynamic data collected, processed, or summarized during the space shuttle program is provided. Tables are designed to provide suvery information to the various space shuttle managerial and technical levels.
Quasi-Hermitian quantum mechanics in phase space
Curtright, Thomas; Veitia, Andrzej
2007-10-15
We investigate quasi-Hermitian quantum mechanics in phase space using standard deformation quantization methods: Groenewold star products and Wigner transforms. We focus on imaginary Liouville theory as a representative example where exact results are easily obtained. We emphasize spatially periodic solutions, compute various distribution functions and phase-space metrics, and explore the relationships between them.
Space law information system design, phase 2
NASA Technical Reports Server (NTRS)
Morenoff, J.; Roth, D. L.; Singleton, J. W.
1973-01-01
Design alternatives were defined for the implementation of a Space Law Information System for the Office of the General Counsel, NASA. A thesaurus of space law terms was developed and a selected document sample indexed on the basis of that thesaurus. Abstracts were also prepared for the sample document set.
Phase partitioning in space and on earth
NASA Technical Reports Server (NTRS)
Van Alstine, James M.; Karr, Laurel J.; Snyder, Robert S.; Matsos, Helen C.; Curreri, Peter A.; Harris, J. Milton; Bamberger, Stephan B.; Boyce, John; Brooks, Donald E.
1987-01-01
The influence of gravity on the efficiency and quality of the impressive separations achievable by bioparticle partitioning is investigated by demixing polymer phase systems in microgravity. The study involves the neutral polymers dextran and polyethylene glycol, which form a two-phase system in aqueous solution at low concentrations. It is found that demixing in low-gravity occurs primarily by coalescence, whereas on earth the demixing occurs because of density differences between the phases.
Tracing the dark matter sheet in phase space
NASA Astrophysics Data System (ADS)
Abel, Tom; Hahn, Oliver; Kaehler, Ralf
2012-11-01
The primordial velocity dispersion of dark matter is small compared to the velocities attained during structure formation. The initial density distribution is close to uniform, and it occupies an initial sheet in phase space that is single valued in velocity space. Because of gravitational forces, this 3D manifold evolves in phase space without ever tearing, conserving phase-space volume and preserving the connectivity of nearby points. N-body simulations already follow the motion of this sheet in phase space. This fact can be used to extract full fine-grained phase-space structure information from existing cosmological N-body simulations. Particles are considered as the vertices of an unstructured 3D mesh moving in 6D phase space. On this mesh, mass density and momentum are uniquely defined. We show how to obtain the space density of the fluid, detect caustics and count the number of streams as well as their individual contributions to any point in configuration space. We calculate the bulk velocity, local velocity dispersions and densities from the sheet - all without averaging over control volumes. This gives a wealth of new information about dark matter fluid flow which had previously been thought of as inaccessible to N-body simulations. We outline how this mapping may be used to create new accurate collisionless fluid simulation codes that may be able to overcome the sparse sampling and unphysical two-body effects that plague current N-body techniques.
Real-space Berry phases: Skyrmion soccer (invited)
Everschor-Sitte, Karin Sitte, Matthias
2014-05-07
Berry phases occur when a system adiabatically evolves along a closed curve in parameter space. This tutorial-like article focuses on Berry phases accumulated in real space. In particular, we consider the situation where an electron traverses a smooth magnetic structure, while its magnetic moment adjusts to the local magnetization direction. Mapping the adiabatic physics to an effective problem in terms of emergent fields reveals that certain magnetic textures, skyrmions, are tailormade to study these Berry phase effects.
Real-space Berry phases: Skyrmion soccer (invited)
NASA Astrophysics Data System (ADS)
Everschor-Sitte, Karin; Sitte, Matthias
2014-05-01
Berry phases occur when a system adiabatically evolves along a closed curve in parameter space. This tutorial-like article focuses on Berry phases accumulated in real space. In particular, we consider the situation where an electron traverses a smooth magnetic structure, while its magnetic moment adjusts to the local magnetization direction. Mapping the adiabatic physics to an effective problem in terms of emergent fields reveals that certain magnetic textures, skyrmions, are tailormade to study these Berry phase effects.
4D phase-space multiplexing for fluorescent microscopy
NASA Astrophysics Data System (ADS)
Liu, Hsiou-Yuan; Zhong, Jingshan; Waller, Laura
2016-03-01
Phase-space measurements enable characterization of second-order spatial coherence properties and can be used for digital aberration removal or 3D position reconstruction. Previous methods use a scanning aperture to measure the phase space spectrogram, which is slow and light inefficient, while also attenuating information about higher-order correlations. We demonstrate a significant improvement of speed and light throughput by incorporating multiplexing techniques into our phase-space imaging system. The scheme implements 2D coded aperture patterning in the Fourier (pupil) plane of a microscope using a Spatial Light Modulator (SLM), while capturing multiple intensity images in real space. We compare various multiplexing schemes to scanning apertures and show that our phase-space reconstructions are accurate for experimental data with biological samples containing many 3D fluorophores.
Selected tether applications in space: Phase 2
NASA Technical Reports Server (NTRS)
Thorsen, M. H.; Lippy, L. J.
1985-01-01
System characteristics and design requirements are assessed for tether deployment. Criteria are established for comparing alternate concepts for: (1) deployment of 220 klb space shuttle from the space station; (2) tether assisted launch of a 20,000 lb payload to geosynchronous orbit; (3) placement of the 20,000 lb AXAF into 320 nmi orbit via orbiter; (4) retrieval of 20,000 lb AXAF from 205 nmi circular orbit for maintenance and reboost to 320 nmi; and (5) tethered OMV rendezvous and retrieval of OTV returning from a geosynchronous mission. Tether deployment systems and technical issues are discussed.
Leptons, Quarks, and Their Antiparticles: A Phase-Space View
NASA Astrophysics Data System (ADS)
Żenczykowski, Piotr
2010-09-01
Recently, a correspondence has been shown to exist between the structure of a single Standard Model generation of elementary particles and the properties of the Clifford algebra of nonrelativistic phase space. Here, this correspondence is spelled out in terms of phase-space variables. Thus, a phase-space interpretation of the connections between leptons, quarks and their antiparticles is proposed, in particular providing a timeless alternative to the standard Stückelberg-Feynman interpretation. The issue of the additivity of canonical momenta is raised and argued to be intimately related to the unobservability of free quarks and the emergence of mesons and baryons.
Longitudinal phase space experiments on the ELSA photoinjector
Dowell, D.H.; Joly, S.; Brion, J.P. de
1995-12-31
The excellent beam quality produced by RF photocathode injectors is well established, andhas been verified by numerous measurements of the transverse emittance. However, there are few experimental determinations of the longitudinal phase space. This paper reports on experiments performed at the ELSA FEL facility to emasure the longitudinal phase space distribution at the exit of the 144 MHz photoinjector cavity. Phase spaces were determined by the analysis of beam energy spectra and pulse shapes at 17.5 MeV for micropulse charges between 0.5 and 5 nC.
Phase Space Distribution Near the Self-Excited Oscillation Threshold
NASA Astrophysics Data System (ADS)
Dhayalan, Yuvaraj; Baskin, Ilya; Shlomi, Keren; Buks, Eyal
2014-05-01
We study the phase space distribution of an optomechanical cavity near the threshold of self-excited oscillation. A fully on-fiber optomechanical cavity is fabricated by patterning a suspended metallic mirror on the tip of the fiber. Optically induced self-excited oscillation of the suspended mirror is observed above a threshold value of the injected laser power. A theoretical analysis based on the Fokker-Planck equation evaluates the expected phase space distribution near threshold. A tomography technique is employed for extracting phase space distribution from the measured reflected optical power vs time in steady state. Comparison between theory and experimental results allows the extraction of the device parameters.
A Simple, Low Cost Longitudinal Phase Space Diagnostic
Bertsche, Kirk; Emma, Paul; Shevchenko, Oleg; /Novosibirsk, IYF
2009-05-15
For proper operation of the LCLS [1] x-ray free-electron laser (FEL), and other similar machines, measurement and control of the electron bunch longitudinal phase space is critical. The LCLS accelerator includes two bunch compressor chicanes to magnify the peak current. These magnetic chicanes can generate significant coherent synchrotron radiation (CSR), which can distort the phase space distribution. We propose a diagnostic scheme by exciting a weak skew quadrupole at an energy-chirped, high dispersion point in the first LCLS bunch compressor (BC1) to reconstruct longitudinal phase space on an OTR screen after BC1, allowing a time-resolved characterization of CSR effects.
The space transportation main engine phase A' study
NASA Technical Reports Server (NTRS)
1987-01-01
The Space Transportation Main Engine Phase A prime study was conducted over a 7 month period as an extension to the Phase A study. The Phase A prime program was designed to expand the study effort completed in Phase A, focusing on the baseline engine configuration selected. Analysis and trade studies were conducted to further optimize some of the major engine subsystems. These changes resulted in improvements to the baseline engine. Several options were evaluated for consideration by vehicle contractors.
Liquid phase sintered compacts in space
NASA Technical Reports Server (NTRS)
Mookherji, T. K.; Mcanelly, W. B.
1974-01-01
A model that will explain the effect of gravity on liquid phase sintering was developed. Wetting characteristics and density segregation which are the two important phenomena in liquid phase sintering are considered in the model development. Experiments were conducted on some selected material combinations to study the gravity effects on liquid phase sintering, and to verify the validity of the model. It is concluded that: (1) The surface tension forces acting on solid particles in a one-g environment are not appreciably different from those anticipated in a 0.00001g/g sub 0 (or lower) environment. (2) The capillary forces are dependent on the contact angle, the quantity of the liquid phase, and the distance between solid particles. (3) The pores (i.e., bubbles) do not appear to be driven to the surface by gravity-produced buoyancy forces. (4) The length of time to produce the same degree of settling in a low-gravity environment will be increased significantly. (5) A low gravity environment would appear to offer a unique means of satisfactorily infiltrating a larger and/or complex shaped compact.
Phase I Space Station power system development
Price, R.O.
1988-10-01
The development of the electric power system (EPS) for the Space Station is discussed. The EPS requirements related to station size, operational lifetime, operational autonomy, and technology evolution are considered. It is suggested that environmental control and life support will require 55 kWe of power. The possible use of solar photovoltaic, solar thermal dynamic, or a hybrid combination of the two are examined.
Phase Space Structures Explain Hydrogen Atom Roaming in Formaldehyde Decomposition.
Mauguière, Frédéric A L; Collins, Peter; Kramer, Zeb C; Carpenter, Barry K; Ezra, Gregory S; Farantos, Stavros C; Wiggins, Stephen
2015-10-15
We re-examine the prototypical roaming reaction--hydrogen atom roaming in formaldehyde decomposition--from a phase space perspective. Specifically, we address the question "why do trajectories roam, rather than dissociate through the radical channel?" We describe and compute the phase space structures that define and control all possible reactive events for this reaction, as well as provide a dynamically exact description of the roaming region in phase space. Using these phase space constructs, we show that in the roaming region, there is an unstable periodic orbit whose stable and unstable manifolds define a conduit that both encompasses all roaming trajectories exiting the formaldehyde well and shepherds them toward the H2···CO well. PMID:26499774
An extensive phase space for the potential martian biosphere.
Jones, Eriita G; Lineweaver, Charles H; Clarke, Jonathan D
2011-12-01
We present a comprehensive model of martian pressure-temperature (P-T) phase space and compare it with that of Earth. Martian P-T conditions compatible with liquid water extend to a depth of ∼310 km. We use our phase space model of Mars and of terrestrial life to estimate the depths and extent of the water on Mars that is habitable for terrestrial life. We find an extensive overlap between inhabited terrestrial phase space and martian phase space. The lower martian surface temperatures and shallower martian geotherm suggest that, if there is a hot deep biosphere on Mars, it could extend 7 times deeper than the ∼5 km depth of the hot deep terrestrial biosphere in the crust inhabited by hyperthermophilic chemolithotrophs. This corresponds to ∼3.2% of the volume of present-day Mars being potentially habitable for terrestrial-like life. PMID:22149914
Wigner function and Schroedinger equation in phase-space representation
Chruscinski, Dariusz; Mlodawski, Krzysztof
2005-05-15
We discuss a family of quasidistributions (s-ordered Wigner functions of Agarwal and Wolf [Phys. Rev. D 2, 2161 (1970); Phys. Rev. D 2, 2187 (1970); Phys. Rev. D 2, 2206 (1970)]) and its connection to the so-called phase space representation of the Schroedinger equation. It turns out that although Wigner functions satisfy the Schroedinger equation in phase space, they have a completely different interpretation.
Kac Moody theories for colored phase space (quantum Hall) droplets
NASA Astrophysics Data System (ADS)
Polychronakos, Alexios P.
2005-04-01
We derive the canonical structure and Hamiltonian for arbitrary deformations of a higher-dimensional (quantum Hall) droplet of fermions with spin or color on a general phase space manifold. Gauge fields are introduced via a Kaluza-Klein construction on the phase space. The emerging theory is a nonlinear higher-dimensional generalization of the gauged Kac-Moody algebra. To leading order in ℏ this reproduces the edge state chiral Wess-Zumino-Witten action of the droplets.
Group theoretical construction of planar noncommutative phase spaces
Ngendakumana, Ancille Todjihoundé, Leonard; Nzotungicimpaye, Joachim
2014-01-15
Noncommutative phase spaces are generated and classified in the framework of centrally extended anisotropic planar kinematical Lie groups as well as in the framework of noncentrally abelian extended planar absolute time Lie groups. Through these constructions the coordinates of the phase spaces do not commute due to the presence of naturally introduced fields giving rise to minimal couplings. By symplectic realizations methods, physical interpretations of generators coming from the obtained structures are given.
Tracing, Analyzing and Visualizing Dark Matter in Phase Space
NASA Astrophysics Data System (ADS)
Hahn, Oliver; Abel, Tom; Kaehler, Ralf
2015-01-01
In a Universe dominated by cold dark matter, structure forms from foldings of a three-dimensional sheet permeating six-dimensional phase space. The dynamics of the sheet is governed by gravity alone, and it never tears or intersects itself in phase space. In position space, these foldings lead to the formation of pancakes, filaments and finally dark matter halos: the cosmic web. N-body simulations already follow the motion of this sheet in phase space. This fact can be used to extract full fine-grained phase-space-structure information from existing cosmological N-body simulations. Particles are considered as the vertices of an unstructured three dimensional mesh, moving in six dimensional phase-space. On this mesh, mass density and momentum are uniquely defined. We show how to obtain the space density of the fluid, local velocity dispersion and detect caustics. We also discuss how information about the sheet can be used to create highly accurate volume visualizations and devise new simulation codes to evolve cold collisionless fluids under self-gravity.
Phase space variations of near equatorially mirroring ring current ions
NASA Technical Reports Server (NTRS)
Williams, D. J.
1981-01-01
Observations of near equatorially mirroring ring current ions before and after a magnetic storm are presented in the form of phase space densities with respect to the first adiabatic invariant. Particle densities were obtained from the medium energy particles instrument covering the energy range 24-2081 keV on ISEE 1 at L values between 3 and 8 earth radii and ratios of the magnetic field at the satellite position to the magnetic field at the magnetic equator less than 1.2. Analysis of the phase space densities through the magnetosphere reveals a well-defined high magnetic moment peak in the prestorm near-equatorial ring current ion phase space density distribution, with the magnetic storm resulting from an enhancement of phase space densities at magnetic moment values below the peak and phase space densities remaining constant above the peak. Results are found to be in good agreement with those obtained by Explorer 45 six years previously, indicating that the observed phase space density variations are characteristic of energetic ion behavior during magnetic storms.
Symmetry of quantum phase space in a degenerate Hamiltonian system
NASA Astrophysics Data System (ADS)
Berman, G. P.; Demikhovskii, V. Ya.; Kamenev, D. I.
2000-09-01
The structure of the global "quantum phase space" is analyzed for the harmonic oscillator perturbed by a monochromatic wave in the limit when the perturbation amplitude is small. Usually, the phenomenon of quantum resonance was studied in nondegenerate [G. M. Zaslavsky, Chaos in Dynamic Systems (Harwood Academic, Chur, 1985)] and degenerate [Demikhovskii, Kamenev, and Luna-Acosta, Phys. Rev. E 52, 3351 (1995)] classically chaotic systems only in the particular regions of the classical phase space, such as the center of the resonance or near the separatrix. The system under consideration is degenerate, and even an infinitely small perturbation generates in the classical phase space an infinite number of the resonant cells which are arranged in the pattern with the axial symmetry of the order 2μ (where μ is the resonance number). We show analytically that the Husimi functions of all Floquet states (the quantum phase space) have the same symmetry as the classical phase space. This correspondence is demonstrated numerically for the Husimi functions of the Floquet states corresponding to the motion near the elliptic stable points (centers of the classical resonance cells). The derived results are valid in the resonance approximation when the perturbation amplitude is small enough, and the stochastic layers in the classical phase space are exponentially thin. The developed approach can be used for studying a global symmetry of more complicated quantum systems with chaotic behavior.
The diffusion of stars through phase space
NASA Technical Reports Server (NTRS)
Binney, James; Lacey, Cedric
1988-01-01
An orbit-averaged Fokker-Planck equation has been derived to study the secular evolution of stellar systems with regular orbits and the heating of stellar disks. It is shown that a population of stars with an initially Maxwellian peculiar-velocity distribution will remain Maxwellian as it diffuses through orbit space only if: (1) a second-order diffusion tensor is proportional to epicycle energy; and (2) the population's velocity dispersion grows as the square root of time. Scattering by ephemeral spiral waves is able to account for the observed kinematics of the solar neighborhood only if the waves have wavelengths in excess of 9 kpc and constantly drifting pattern speeds.
Space power demonstrator engine, phase 1
NASA Technical Reports Server (NTRS)
1987-01-01
The design, analysis, and preliminary test results for a 25 kWe Free-Piston Stirling engine with integral linear alternators are described. The project is conducted by Mechanical Technology under the direction of LeRC as part of the SP-100 Nuclear Space Power Systems Program. The engine/alternator system is designed to demonstrate the following performance: (1) 25 kWe output at a specific weight less than 8 kg/kW; (2) 25 percent efficiency at a temperature ratio of 2.0; (3) low vibration (amplitude less than .003 in); (4) internal gas bearings (no wear, no external pump); and (5) heater temperature/cooler temperature from 630 to 315 K. The design approach to minimize vibration is a two-module engine (12.5 kWe per module) in a linearly-opposed configuration with a common expansion space. The low specific weight is obtained at high helium pressure (150 bar) and high frequency (105 Hz) and by using high magnetic strength (samarium cobalt) alternator magnets. Engine tests began in June 1985; 16 months following initiation of engine and test cell design. Hydrotest and consequent engine testing to date has been intentionally limited to half pressure, and electrical power output is within 15 to 20 percent of design predictions.
Space transfer concepts and analyses for exploration missions, phase 3
NASA Technical Reports Server (NTRS)
Woodcock, Gordon R.
1993-01-01
This report covers the third phase of a broad-scoped and systematic study of space transfer concepts for human lunar and Mars missions. The study addressed issues that were raised during Phase 2, developed generic Mars missions profile analysis data, and conducted preliminary analysis of the Mars in-space transportation requirements and implementation from Stafford Committee Synthesis Report. The major effort of the study was the development of the first Lunar Outpost (FLO) baseline which evolved from the Space Station Freedom Hab Module. Modifications for the First Lunar Outpost were made to meet mission requirements and technology advancements.
Phase-Space Detection of Cyber Events
Hernandez Jimenez, Jarilyn M; Ferber, Aaron E; Prowell, Stacy J; Hively, Lee M
2015-01-01
Energy Delivery Systems (EDS) are a network of processes that produce, transfer and distribute energy. EDS are increasingly dependent on networked computing assets, as are many Industrial Control Systems. Consequently, cyber-attacks pose a real and pertinent threat, as evidenced by Stuxnet, Shamoon and Dragonfly. Hence, there is a critical need for novel methods to detect, prevent, and mitigate effects of such attacks. To detect cyber-attacks in EDS, we developed a framework for gathering and analyzing timing data that involves establishing a baseline execution profile and then capturing the effect of perturbations in the state from injecting various malware. The data analysis was based on nonlinear dynamics and graph theory to improve detection of anomalous events in cyber applications. The goal was the extraction of changing dynamics or anomalous activity in the underlying computer system. Takens' theorem in nonlinear dynamics allows reconstruction of topologically invariant, time-delay-embedding states from the computer data in a sufficiently high-dimensional space. The resultant dynamical states were nodes, and the state-to-state transitions were links in a mathematical graph. Alternatively, sequential tabulation of executing instructions provides the nodes with corresponding instruction-to-instruction links. Graph theorems guarantee graph-invariant measures to quantify the dynamical changes in the running applications. Results showed a successful detection of cyber events.
Quantum de Finetti theorem in phase-space representation
Leverrier, Anthony; Cerf, Nicolas J.
2009-07-15
The quantum versions of de Finetti's theorem derived so far express the convergence of n-partite symmetric states, i.e., states that are invariant under permutations of their n parties, toward probabilistic mixtures of independent and identically distributed (IID) states of the form {sigma}{sup xn}. Unfortunately, these theorems only hold in finite-dimensional Hilbert spaces, and their direct generalization to infinite-dimensional Hilbert spaces is known to fail. Here, we address this problem by considering invariance under orthogonal transformations in phase space instead of permutations in state space, which leads to a quantum de Finetti theorem particularly relevant to continuous-variable systems. Specifically, an n-mode bosonic state that is invariant with respect to this continuous symmetry in phase space is proven to converge toward a probabilistic mixture of IID Gaussian states (actually, n identical thermal states)
Multivariable Hermite polynomials and phase-space dynamics
NASA Technical Reports Server (NTRS)
Dattoli, G.; Torre, Amalia; Lorenzutta, S.; Maino, G.; Chiccoli, C.
1994-01-01
The phase-space approach to classical and quantum systems demands for advanced analytical tools. Such an approach characterizes the evolution of a physical system through a set of variables, reducing to the canonically conjugate variables in the classical limit. It often happens that phase-space distributions can be written in terms of quadratic forms involving the above quoted variables. A significant analytical tool to treat these problems may come from the generalized many-variables Hermite polynomials, defined on quadratic forms in R(exp n). They form an orthonormal system in many dimensions and seem the natural tool to treat the harmonic oscillator dynamics in phase-space. In this contribution we discuss the properties of these polynomials and present some applications to physical problems.
Phase-space approach to continuous variable quantum teleportation
Ban, Masashi
2004-05-01
The phase-space method is applied for considering continuous variable quantum teleportation. It is found that the continuous variable quantum teleportation transforms the s-parametrized phase-space function of an input state into the (s+{delta})-parametrized phase-space function, where the parameter {delta} is determined by the shared quantum entanglement. It is shown from this result that the Wigner function of the teleported state is always non-negative for F{sub c}{<=}2/3 and the Glauber-Sudarshan P function non-negative for F{sub c}{<=}1/2, where F{sub c} is the fidelity of the coherent-state teleportation. Furthermore the fidelity between input and output states is calculated when Gaussian states are teleported.
Explicit methods in extended phase space for inseparable Hamiltonian problems
NASA Astrophysics Data System (ADS)
Pihajoki, Pauli
2015-03-01
We present a method for explicit leapfrog integration of inseparable Hamiltonian systems by means of an extended phase space. A suitably defined new Hamiltonian on the extended phase space leads to equations of motion that can be numerically integrated by standard symplectic leapfrog (splitting) methods. When the leapfrog is combined with coordinate mixing transformations, the resulting algorithm shows good long term stability and error behaviour. We extend the method to non-Hamiltonian problems as well, and investigate optimal methods of projecting the extended phase space back to original dimension. Finally, we apply the methods to a Hamiltonian problem of geodesics in a curved space, and a non-Hamiltonian problem of a forced non-linear oscillator. We compare the performance of the methods to a general purpose differential equation solver LSODE, and the implicit midpoint method, a symplectic one-step method. We find the extended phase space methods to compare favorably to both for the Hamiltonian problem, and to the implicit midpoint method in the case of the non-linear oscillator.
κ-Deformed Phase Space, Hopf Algebroid and Twisting
NASA Astrophysics Data System (ADS)
Jurić; , Tajron; Kovačević, Domagoj; Meljanac, Stjepan
2014-11-01
Hopf algebroid structures on the Weyl algebra (phase space) are presented. We define the coproduct for the Weyl generators from Leibniz rule. The codomain of the coproduct is modified in order to obtain an algebra structure. We use the dual base to construct the target map and antipode. The notion of twist is analyzed for κ-deformed phase space in Hopf algebroid setting. It is outlined how the twist in the Hopf algebroid setting reproduces the full Hopf algebra structure of κ-Poincaré algebra. Several examples of realizations are worked out in details.
MUB Entanglement Patterns by Transformations in Phase Space
NASA Astrophysics Data System (ADS)
Lawrence, Jay
2011-03-01
All possible MUB entanglement patterns for systems of N prime-state particles are obtained from standard ones by unitary transformations in the Hilbert space, thus preserving the relationships between the generalized Pauli operators, the phase point operators, and the MUB projectors. The transformations are described geometrically in discrete phase space. Illustrative examples show the invariance of the total entanglement content and the connection of entanglement with Galois fields. Different field representations for the same dimension may produce inequivalent MUB sets. This work provides alternative constructions and generalizes previous work on qubit systems [1,2].
The solidification of monotectic alloys - Microstructures and phase spacings
NASA Technical Reports Server (NTRS)
Grugel, R. N.; Hellawell, A.; Lograsso, T. A.
1984-01-01
The microstructures of directionally grown monotectic alloys in metallic and organic systems fall into two categories those which can form aligned fibrous composite structures with even phase spacings and fiber sections, and those in which the phase distribution is coarser and less regular. This division appears to relate to the form of the phase diagram and has been rationalized by Cahn (1977, 1979) in terms of the relative surface energies between solid and two liquids to give steady state or nonsteady state profiles. The transition in growth behavior occurs when the ratio of the monotectic temperature to that of the upper consolute temperature is approximately 0.9. Differences in phase spacings between a range of monotectic and eutectic systems are discussed in terms of the expected growth interface shapes and the factors which will influence them.
Adaptive optics and phase diversity imaging for responsive space applications.
Smith, Mark William; Wick, David Victor
2004-11-01
The combination of phase diversity and adaptive optics offers great flexibility. Phase diverse images can be used to diagnose aberrations and then provide feedback control to the optics to correct the aberrations. Alternatively, phase diversity can be used to partially compensate for aberrations during post-detection image processing. The adaptive optic can produce simple defocus or more complex types of phase diversity. This report presents an analysis, based on numerical simulations, of the efficiency of different modes of phase diversity with respect to compensating for specific aberrations during post-processing. It also comments on the efficiency of post-processing versus direct aberration correction. The construction of a bench top optical system that uses a membrane mirror as an active optic is described. The results of characterization tests performed on the bench top optical system are presented. The work described in this report was conducted to explore the use of adaptive optics and phase diversity imaging for responsive space applications.
Phase-field study of spacing evolution during transient growth
NASA Astrophysics Data System (ADS)
Gurevich, Sebastian; Amoorezaei, Morteza; Provatas, Nikolas
2010-11-01
The primary spacing of a dendritic array grown under transient growth conditions displays a distribution of wavelengths. The average primary spacing is shown, both experimentally and numerically, to evolve between characteristic incubation periods during which the distribution of wavelengths remains essentially stable. Our primary spacing results display a gradual transition period from one spacing range to another, consistent with the fact that the abrupt doubling of spacing predicted by Warren and Langer for an idealized periodic array affects different wavelengths of the distribution at different times. This transition is shown to depend on the rate of change in growth speed using phase-field simulations of directional solidification where the pulling speed is ramped at different rates. In particular, for high rates of change of the pulling speed we observe temporary marginally stable array configurations separated by relatively short lived transitions, while for lower rates of change of the pulling speed the distinction between incubation and transition periods disappears.
Naval Space Surveillance Center uses of time, frequency, and phase
NASA Technical Reports Server (NTRS)
Hayden, Carroll C.; Knowles, Stephen H.
1992-01-01
The Naval Space Surveillance Center (NAVSPASUR) is an operational naval command that has the mission of determining the location of all manmade objects in space and transmitting information on objects of interest to the fleet. NAVSPASUR operates a 217 MHz radar fence that has 9 transmitting and receiving stations deployed in a line across southern Continental United States (CONUS). This surveillance fence provides unalerted detection of satellites overflying CONUS. NAVSPASUR also maintains a space catalog of all orbiting space objects. NAVSPASUR plays an important role as operational alternate to the primary national Space Surveillance Center (SSC) and Space Defence Operations Center (SPADOC). In executing these responsibilities, NAVSPASUR needs precise and/or standardized time and frequency in a number of applications. These include maintenance of the radar fence references to specification, and coordination with other commands and agencies for data receipt and dissemination. Precise time and frequency must be maintained within each site to enable proper operation of the interferometry phasing technique used. Precise time-of-day clocking must exist between sites for proper intersite coordination. Phase may be considered a derivative of time and frequency. Its control within each transmitter or receiver site is of great importance to NAVSPASUR because of the operation of the sensor as an interferometer system, with source direction angles as the primary observable. Determination of the angular position of a satellite is directly dependent on the accuracy with which the differential phase between spaced subarrays can be measured at each receiver site. Various aspects of the NAVSPASUR are discussed with respect to time, frequency, and phase.
Two Phase Flow and Space-Based Applications
NASA Technical Reports Server (NTRS)
McQuillen, John
1999-01-01
A reduced gravity environment offers the ability to remove the effect of buoyancy on two phase flows whereby density differences that normally would promote relative velocities between the phases and also alter the shape of the interface are removed. However, besides being a potent research tool, there are also many space-based technologies that will either utilize or encounter two-phase flow behavior, and as a consequence, several questions must be addressed. This paper presents some of these technologies missions. Finally, this paper gives a description of web-sites for some funding.
Quantum particles from coarse grained classical probabilities in phase space
Wetterich, C.
2010-07-15
Quantum particles can be obtained from a classical probability distribution in phase space by a suitable coarse graining, whereby simultaneous classical information about position and momentum can be lost. For a suitable time evolution of the classical probabilities and choice of observables all features of a quantum particle in a potential follow from classical statistics. This includes interference, tunneling and the uncertainty relation.
Strong Field Double Ionization: The Phase Space Perspective
Mauger, F.; Chandre, C.; Uzer, T.
2009-05-01
We identify the phase-space structures that regulate atomic double ionization in strong ultrashort laser pulses. The emerging dynamical picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons, and leads to verifiable predictions on the characteristic features of the 'knee', a hallmark of the nonsequential process.
Phase space flow of particles in squeezed states
NASA Technical Reports Server (NTRS)
Ceperley, Peter H.
1994-01-01
The manipulation of noise and uncertainty in squeezed states is governed by the wave nature of the quantum mechanical particles in these states. This paper uses a deterministic model of quantum mechanics in which real guiding waves control the flow of localized particles. This model will be used to examine the phase space flow of particles in typical squeezed states.
Depositing spacing layers on magnetic film with liquid phase epitaxy
NASA Technical Reports Server (NTRS)
Moody, J. W.; Shaw, R. W.; Sanfort, R. M.
1975-01-01
Liquid phase epitaxy spacing layer is compatible with systems which are hard-bubble proofed by use of second magnetic garnet film as capping layer. Composite is superior in that: circuit fabrication time is reduced; adherence is superior; visibility is better; and, good match of thermal expansion coefficients is provided.
Dimension of quantum phase space measured by photon correlations
NASA Astrophysics Data System (ADS)
Leuchs, Gerd; Glauber, Roy J.; Schleich, Wolfgang P.
2015-06-01
We show that the different values 1, 2 and 3 of the normalized second-order correlation function {g}(2)(0) corresponding to a coherent state, a thermal state and a highly squeezed vacuum originate from the different dimensionality of these states in phase space. In particular, we derive an exact expression for {g}(2)(0) in terms of the ratio of the moments of the classical energy evaluated with the Wigner function of the quantum state of interest and corrections proportional to the reciprocal of powers of the average number of photons. In this way we establish a direct link between {g}(2)(0) and the shape of the state in phase space. Moreover, we illuminate this connection by demonstrating that in the semi-classical limit the familiar photon statistics of a thermal state arise from an area in phase space weighted by a two-dimensional Gaussian, whereas those of a highly squeezed state are governed by a line-integral of a one-dimensional Gaussian. We dedicate this article to Margarita and Vladimir Man’ko on the occasion of their birthdays. The topic of our contribution is deeply rooted in and motivated by their love for non-classical light, quantum mechanical phase space distribution functions and orthogonal polynomials. Indeed, through their articles, talks and most importantly by many stimulating discussions and intensive collaborations with us they have contributed much to our understanding of physics. Happy birthday to you both!
Geometrical Series and Phase Space in a Finite Oscillatory Motion
ERIC Educational Resources Information Center
Mareco, H. R. Olmedo
2006-01-01
This article discusses some interesting physical properties of oscillatory motion of a particle on two joined inclined planes. The geometrical series demonstrates that the particle will oscillate during a finite time. Another detail is the converging path to the origin of the phase space. Due to its simplicity, this motion may be used as a…
Phase-locked injection laser arrays with variable stripe spacing
NASA Technical Reports Server (NTRS)
Ackley, Donald E.; Butler, Jerome K.; Ettenberg, Michael
1986-01-01
A phase-locked injection laser array is described which utilizes variations in spacing of identical lasing elements to vary the coupling between them. A coupled-mode analysis indicates that excellent matching of fundamental array mode to a uniform gain distribution can be obtained. Observation of the array emission patterns confirms the results of the coupled-mode analysis.
Twisted geometries: A geometric parametrization of SU(2) phase space
Freidel, Laurent; Speziale, Simone
2010-10-15
A cornerstone of the loop quantum gravity program is the fact that the phase space of general relativity on a fixed graph can be described by a product of SU(2) cotangent bundles per edge. In this paper we show how to parametrize this phase space in terms of quantities describing the intrinsic and extrinsic geometry of the triangulation dual to the graph. These are defined by the assignment to each face of its area, the two unit normals as seen from the two polyhedra sharing it, and an additional angle related to the extrinsic curvature. These quantities do not define a Regge geometry, since they include extrinsic data, but a looser notion of discrete geometry which is twisted in the sense that it is locally well-defined, but the local patches lack a consistent gluing among each other. We give the Poisson brackets among the new variables, and exhibit a symplectomorphism which maps them into the Poisson brackets of loop gravity. The new parametrization has the advantage of a simple description of the gauge-invariant reduced phase space, which is given by a product of phase spaces associated to edges and vertices, and it also provides an Abelianization of the SU(2) connection. The results are relevant for the construction of coherent states and, as a byproduct, contribute to clarify the connection between loop gravity and its subset corresponding to Regge geometries.
Painting the Phase Space Portrait of an Integrable Dynamical System
NASA Astrophysics Data System (ADS)
Coffey, Shannon; Deprit, Andre; Deprit, Etienne; Healy, Liam
1990-02-01
For an integrable dynamical system with one degree of freedom, "painting" the integral over the phase space proves to be very effective for uncovering the global flow down to minute details. Applied to the main problem in artificial satellite theory, for instance, the technique reveals an intricate configuration of equilibria and bifurcations when the polar component of the angular momentum approaches zero.
Phase-space reconstruction of focused x-ray fields
Tran, Chanh Q.; Mancuso, Adrian P.; Dhal, Bipin B.; Nugent, Keith A.; Peele, Andrew G.; Cai, Zhonghou; Paterson, David
2006-01-01
The phase-space tomography is used to reconstruct x-ray beams focused using a compound refractive lens, showing that it is possible to decouple the effect of aberrations in the optical system from the field and therefore measure both them and the original field. The complex coherence function is recovered and found to be consistent with expectations.
Vital phase of space science. [solar terrestrial interactions
NASA Technical Reports Server (NTRS)
Parker, E. N.
1994-01-01
Space science began with the indirect phase where the activity in space was inferred from such terrestrial phenomena as geomagnetic storms, ionospheric variations, and fluctuations in the cosmic ray intensity. The direct phase was initiated with spaceflight placing instruments directly in space and permitting the direct observation of UV and X rays, as well as precision observations of solar luminosity variations. The evidence from these many direct studies, together with the historical record of terrestrial conditions, shows that the variations of the luminosity of the Sun affect the terrestrial atmosphere at all levels, with devastating changes in climate tracking the major changes in the activity level and luminosity of the Sun. The quantification and understanding of this vital connection should be the first priority of space science and geophysics, from oceans and atmosphere through the ionosphere, magnetosphere, and all the way to the convective zone of the Sun. It becomes the vital phase of space science, focused on the basic science of the changing habitability of Earth.
Phase-space exploration in nuclear giant resonance decay
Drozdz, S.; Nishizaki, S.; Wambach, J.; Speth, J. Institute of Nuclear Physics, PL-31-342 Krakow Department of Physics, University of Illinois at Urbana, Illinois 61801 College of Humanities and Social Sciences, Iwate University, Ueda 3-18-34, Morioka 020 )
1995-02-13
The rate of phase-space exploration in the decay of isovector and isoscalar giant quadrupole resonances in [sup 40]Ca is analyzed. The study is based on the time dependence of the survival probability and of the spectrum of generalized entropies evaluated in the space of one-particle--one-hole (1p-1h) and 2p-2h states. Three different cases for the level distribution of 2p-2h background states, corresponding to (a) high degeneracy, (b) classically regular motion, and (c) classically chaotic motion, are studied. In the latter case the isovector excitation evolves almost statistically while the isoscalar excitation remains largely localized, even though it penetrates the whole available phase space.
Extended phase space description of human-controlled systems dynamics
NASA Astrophysics Data System (ADS)
Zgonnikov, Arkady; Lubashevsky, Ihor
2014-03-01
Humans are often incapable of precisely identifying and implementing the desired control strategy in controlling unstable dynamical systems. That is, the operator of a dynamical system treats the current control effort as acceptable even if it deviates slightly from the desired value, and starts correcting the actions only when the deviation has become evident. We argue that the standard Newtonian approach does not allow such behavior to be modeled. Instead, the physical phase space of a controlled system should be extended with an independent phase variable characterizing the motivated actions of the operator. The proposed approach is illustrated via a simple non-Newtonian model capturing the operators' fuzzy perception of their own actions. The properties of the model are investigated analytically and numerically; the results confirm that the extended phase space may aid in capturing the intricate dynamical properties of human-controlled systems.
Phase-space Dynamics of Runaway Electrons In Tokamaks
Xiaoyin Guan, Hong Qin, and Nathaniel J. Fisch
2010-08-31
The phase-space dynamics of runaway electrons is studied, including the influence of loop voltage, radiation damping, and collisions. A theoretical model and a numerical algorithm for the runaway dynamics in phase space are developed. Instead of standard integrators, such as the Runge-Kutta method, a variational symplectic integrator is applied to simulate the long-term dynamics of a runaway electron. The variational symplectic integrator is able to globally bound the numerical error for arbitrary number of time-steps, and thus accurately track the runaway trajectory in phase space. Simulation results show that the circulating orbits of runaway electrons drift outward toward the wall, which is consistent with experimental observations. The physics of the outward drift is analyzed. It is found that the outward drift is caused by the imbalance between the increase of mechanical angular momentum and the input of toroidal angular momentum due to the parallel acceleration. An analytical expression of the outward drift velocity is derived. The knowledge of trajectory of runaway electrons in configuration space sheds light on how the electrons hit the first wall, and thus provides clues for possible remedies.
Kinetic solvers with adaptive mesh in phase space.
Arslanbekov, Robert R; Kolobov, Vladimir I; Frolova, Anna A
2013-12-01
An adaptive mesh in phase space (AMPS) methodology has been developed for solving multidimensional kinetic equations by the discrete velocity method. A Cartesian mesh for both configuration (r) and velocity (v) spaces is produced using a "tree of trees" (ToT) data structure. The r mesh is automatically generated around embedded boundaries, and is dynamically adapted to local solution properties. The v mesh is created on-the-fly in each r cell. Mappings between neighboring v-space trees is implemented for the advection operator in r space. We have developed algorithms for solving the full Boltzmann and linear Boltzmann equations with AMPS. Several recent innovations were used to calculate the discrete Boltzmann collision integral with dynamically adaptive v mesh: the importance sampling, multipoint projection, and variance reduction methods. We have developed an efficient algorithm for calculating the linear Boltzmann collision integral for elastic and inelastic collisions of hot light particles in a Lorentz gas. Our AMPS technique has been demonstrated for simulations of hypersonic rarefied gas flows, ion and electron kinetics in weakly ionized plasma, radiation and light-particle transport through thin films, and electron streaming in semiconductors. We have shown that AMPS allows minimizing the number of cells in phase space to reduce the computational cost and memory usage for solving challenging kinetic problems. PMID:24483578
Probabilistic Q-function distributions in fermionic phase-space
NASA Astrophysics Data System (ADS)
Rosales-Zárate, Laura E. C.; Drummond, P. D.
2015-03-01
We obtain a positive probability distribution or Q-function for an arbitrary fermionic many-body system. This is different to previous Q-function proposals, which were either restricted to a subspace of the overall Hilbert space, or used Grassmann methods that do not give probabilities. The fermionic Q-function obtained here is constructed using normally ordered Gaussian operators, which include both non-interacting thermal density matrices and BCS states. We prove that the Q-function exists for any density matrix, is real and positive, and has moments that correspond to Fermi operator moments. It is defined on a finite symmetric phase-space equivalent to the space of real, antisymmetric matrices. This has the natural SO(2M) symmetry expected for Majorana fermion operators. We show that there is a physical interpretation of the Q-function: it is the relative probability for observing a given Gaussian density matrix. The distribution has a uniform probability across the space at infinite temperature, while for pure states it has a maximum value on the phase-space boundary. The advantage of probabilistic representations is that they can be used for computational sampling without a sign problem.
Kinetic solvers with adaptive mesh in phase space
NASA Astrophysics Data System (ADS)
Arslanbekov, Robert R.; Kolobov, Vladimir I.; Frolova, Anna A.
2013-12-01
An adaptive mesh in phase space (AMPS) methodology has been developed for solving multidimensional kinetic equations by the discrete velocity method. A Cartesian mesh for both configuration (r) and velocity (v) spaces is produced using a “tree of trees” (ToT) data structure. The r mesh is automatically generated around embedded boundaries, and is dynamically adapted to local solution properties. The v mesh is created on-the-fly in each r cell. Mappings between neighboring v-space trees is implemented for the advection operator in r space. We have developed algorithms for solving the full Boltzmann and linear Boltzmann equations with AMPS. Several recent innovations were used to calculate the discrete Boltzmann collision integral with dynamically adaptive v mesh: the importance sampling, multipoint projection, and variance reduction methods. We have developed an efficient algorithm for calculating the linear Boltzmann collision integral for elastic and inelastic collisions of hot light particles in a Lorentz gas. Our AMPS technique has been demonstrated for simulations of hypersonic rarefied gas flows, ion and electron kinetics in weakly ionized plasma, radiation and light-particle transport through thin films, and electron streaming in semiconductors. We have shown that AMPS allows minimizing the number of cells in phase space to reduce the computational cost and memory usage for solving challenging kinetic problems.
Space transfer vehicle concepts and requirements study, phase 2
NASA Technical Reports Server (NTRS)
Cannon, Jeffrey H.; Vinopal, Tim; Andrews, Dana; Richards, Bill; Weber, Gary; Paddock, Greg; Maricich, Peter; Bouton, Bruce; Hagen, Jim; Kolesar, Richard
1992-01-01
This final report is a compilation of the Phase 1 and Phase 2 study findings and is intended as a Space Transfer Vehicle (STV) 'users guide' rather than an exhaustive explanation of STV design details. It provides a database for design choices in the general areas of basing, reusability, propulsion, and staging; with selection criteria based on cost, performance, available infrastructure, risk, and technology. The report is organized into the following three parts: (1) design guide; (2) STV Phase 1 Concepts and Requirements Study Summary; and (3) STV Phase 2 Concepts and Requirements Study Summary. The overall objectives of the STV study were to: (1) define preferred STV concepts capable of accommodating future exploration missions in a cost-effective manner; (2) determine the level of technology development required to perform these missions in the most cost effective manner; and (3) develop a decision database of programmatic approaches for the development of an STV concept.
Asteroid orbital inversion using uniform phase-space sampling
NASA Astrophysics Data System (ADS)
Muinonen, K.; Pentikäinen, H.; Granvik, M.; Oszkiewicz, D.; Virtanen, J.
2014-07-01
We review statistical inverse methods for asteroid orbit computation from a small number of astrometric observations and short time intervals of observations. With the help of Markov-chain Monte Carlo methods (MCMC), we present a novel inverse method that utilizes uniform sampling of the phase space for the orbital elements. The statistical orbital ranging method (Virtanen et al. 2001, Muinonen et al. 2001) was set out to resolve the long-lasting challenges in the initial computation of orbits for asteroids. The ranging method starts from the selection of a pair of astrometric observations. Thereafter, the topocentric ranges and angular deviations in R.A. and Decl. are randomly sampled. The two Cartesian positions allow for the computation of orbital elements and, subsequently, the computation of ephemerides for the observation dates. Candidate orbital elements are included in the sample of accepted elements if the χ^2-value between the observed and computed observations is within a pre-defined threshold. The sample orbital elements obtain weights based on a certain debiasing procedure. When the weights are available, the full sample of orbital elements allows the probabilistic assessments for, e.g., object classification and ephemeris computation as well as the computation of collision probabilities. The MCMC ranging method (Oszkiewicz et al. 2009; see also Granvik et al. 2009) replaces the original sampling algorithm described above with a proposal probability density function (p.d.f.), and a chain of sample orbital elements results in the phase space. MCMC ranging is based on a bivariate Gaussian p.d.f. for the topocentric ranges, and allows for the sampling to focus on the phase-space domain with most of the probability mass. In the virtual-observation MCMC method (Muinonen et al. 2012), the proposal p.d.f. for the orbital elements is chosen to mimic the a posteriori p.d.f. for the elements: first, random errors are simulated for each observation, resulting in
On the Landau system in noncommutative phase-space
NASA Astrophysics Data System (ADS)
Gangopadhyay, Sunandan; Saha, Anirban; Halder, Aslam
2015-12-01
We consider the Landau system in a canonically noncommutative phase-space. A set of generalized transformations containing scaling parameters is derived which maps the NC problem to an equivalent commutative problem. The energy spectrum admits NC corrections which are computed using the explicit NC variables as well as the commutative-equivalent variables. Their exact matching solidifies the evidence of the equivalence of the two approaches. We also obtain the magnetic length and level degeneracy, which admit NC corrections. We further study the Aharonov-Bohm effect where the phase-shift is found to alter due to noncommutativity and also depends on the scaling parameters.
Nonclassicality phase-space functions: more insight with fewer detectors.
Luis, Alfredo; Sperling, Jan; Vogel, Werner
2015-03-13
Systems of on-off detectors are well established for measuring radiation fields in the regime of small photon numbers. We propose to combine these detector systems with unbalanced homodyning with a weak local oscillator. This approach yields phase-space functions, which represent the click counterpart of the s parametrized quasiprobabilities of standard photoelectric detection theory. This introduced class of distributions can be directly sampled from the measured click-counting statistics. Therefore, our technique visualizes nonclassical effects without further data processing. Surprisingly, a small number of on-off diodes can yield more insight than perfect photon number resolution. Quantum signatures in the particle and wave domain of the quantized radiation field, as shown by photon number and squeezed states, respectively, will be uncovered in terms of negativities of the sampled phase-space functions. Application in the vast fields of quantum optics and quantum technology will benefit from our efficient nonclassicality characterization approach. PMID:25815932
On a quantum algebraic approach to a generalized phase space
NASA Astrophysics Data System (ADS)
Bohm, D.; Hiley, B. J.
1981-04-01
We approach the relationship between classical and quantum theories in a new way, which allows both to be expressed in the same mathematical language, in terms of a matrix algebra in a phase space. This makes clear not only the similarities of the two theories, but also certain essential differences, and lays a foundation for understanding their relationship. We use the Wigner-Moyal transformation as a change of representation in phase space, and we avoid the problem of “negative probabilities” by regarding the solutions of our equations as constants of the motion, rather than as statistical weight factors. We show a close relationship of our work to that of Prigogine and his group. We bring in a new nonnegative probability function, and we propose extensions of the theory to cover thermodynamic processes involving entropy changes, as well as the usual reversible processes.
Large space telescope, phase A. Volume 1: Executive summary
NASA Technical Reports Server (NTRS)
1972-01-01
The Phase A study of the Large Space Telescope (LST) is reported. The study defines an LST concept based on the broad mission guidelines provided by the Office of Space Science (OSS), the scientific requirements developed by OSS with the scientific community, and an understanding of long range NASA planning current at the time the study was performed. The LST is an unmanned astronomical observatory facility, consisting of an optical telescope assembly (OTA), scientific instrument package (SIP), and a support systems module (SSM). The report consists of five volumes. The report describes the constraints and trade off analyses that were performed to arrive at a reference design for each system and for the overall LST configuration. A low cost design approach was followed in the Phase A study. This resulted in the use of standard spacecraft hardware, the provision for maintenance at the black box level, growth potential in systems designs, and the sharing of shuttle maintenance flights with other payloads.
Order parameter aided phase space exploration under extreme conditions
NASA Astrophysics Data System (ADS)
Samanta, Amit; Hamel, Sebastian; Schwegler, Eric
Efficient exploration of configuration space and identification of metastable structures in condensed phase systems are challenging from both computational as well as algorithmic perspectives. In this talk I will illustrate how we can extend the recently proposed order-parameter aided temperature accelerated sampling schemes to efficiently and systematically explore free energy surfaces, and search for metastable states and reaction pathways within the framework of density functional theory based molecular dynamics. I will illustrate how this sampling scheme can be used to explore the relevant parts of configuration space in prototypical materials, like SiO2 and identify the different metastable structures, transition pathways and phase boundaries. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Communication: Phase space wavelets for solving Coulomb problems.
Shimshovitz, Asaf; Tannor, David J
2012-09-14
Recently we introduced a phase space approach for solving the time-independent Schrödinger equation using a periodic von Neumann basis with bi-orthogonal exchange (pvb) [A. Shimshovitz and D. J. Tannor, Phys. Rev. Lett. 109, 070402 (2012)]. Here we extend the approach to allow a wavelet scaling of the phase space Gaussians. The new basis set, which we call the wavelet pvb basis, is simple to implement and provides an appealing alternative to other wavelet approaches. For the 1D Coulomb problems tested in this paper, the method reduces the size of the basis relative to the Fourier grid method by a factor of 13-60. The savings in basis set size is predicted to grow steeply as the dimensionality increases. PMID:22979843
Space shuttle phase B wind tunnel test database
NASA Technical Reports Server (NTRS)
Glynn, J. L.; Poucher, D. E.
1988-01-01
Archived wind tunnel test data are available for flyback booster or other alternate recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data were acquired by competing contractors and NASA centers for an extensive variety of configurations with an array of wing and body planforms. This wind tunnel test data has been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retro-glide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks and double delta wings.
Visualizing the quantum interaction picture in phase space
NASA Astrophysics Data System (ADS)
Mehmani, Bahar; Aiello, Andrea
2012-09-01
We present a graphical example of the interaction picture-time evolution. Our aim is to help students understand in a didactic manner the simplicity that this picture provides. Visualizing the interaction picture unveils its advantages, which are hidden behind the involved mathematics. Specifically, we show that the time evolution of a driven harmonic oscillator in the interaction picture corresponds to a local transformation of a phase space-reference frame into the one that is co-rotating with the Wigner function.
Phase space representation of spatially partially coherent imaging.
Castaneda, Roman
2008-08-01
The phase space representation of imaging with optical fields in any state of spatial coherence is developed by using spatial coherence wavelets. It leads to new functions for describing the optical transfer and response of imaging systems when the field is represented by Wigner distribution functions. Specific imaging cases are analyzed in this context, and special attention is devoted to the imaging of two point sources. PMID:18670542
The ESA Virtual Space Weather Modelling Centre - Phase 1
NASA Astrophysics Data System (ADS)
Poedts, Stefaan
The ESA ITT project (AO/1-6738/11/NL/AT) to develop Phase 1 of a Virtual Space Weather Modelling Centre has the following objectives and scope: 1. The construction of a long term (~10 yrs) plan for the future development of a European virtual space weather modelling centre consisting of a new ‘open’ and distributed framework for the coupling of physics based models for space weather phenomena; 2. The assessment of model capabilities and the amount of work required to make them operational by integrating them in this framework and the identification of computing and networking requirements to do so. 3. The design of a system to enable models and other components to be installed locally or geographically distributed and the creation of a validation plan including a system of metrics for testing results. The consortium that took up this challenge involves: 1)the Katholieke Universiteit Leuven (Prime Contractor, coordinator: Prof. S. Poedts); 2) the Belgian Institute for Space Aeronomy (BIRA-IASB); 3) the Royal Observatory of Belgium (ROB); 4) the Von Karman Institute (VKI); 5) DH Consultancy (DHC); 6) Space Applications Services (SAS). The project started on May 14 2012, and will finish in May 2014. Thus, by the time of the meeting, both Phase 1A and Phase 1B (the development of the prototype) will be finished. The final report will be presented incl. the architecture decisions made, the framework, the current models integrated already as well as the model couplers installed. The prototype VSWMC will be demonstrated.
Medical care capabilities for Space Station Freedom: A phase approach
NASA Technical Reports Server (NTRS)
Doarn, C. R.; Lloyd, C. W.
1992-01-01
As a result of Congressional mandate Space Station Freedom (SSF) was restructured. This restructuring activity has affected the capabilities for providing medical care on board the station. This presentation addresses the health care facility to be built and used on the orbiting space station. This unit, named the Health Maintenance Facility (HMF) is based on and modeled after remote, terrestrial medical facilities. It will provide a phased approach to health care for the crews of SSF. Beginning with a stabilization and transport phase, HMF will expand to provide the most advanced state of the art therapeutic and diagnostic capabilities. This presentation details the capabilities of such a phased HMF. As Freedom takes form over the next decade there will be ever-increasing engineering and scientific developmental activities. The HMF will evolve with this process until it eventually reaches a mature, complete stand-alone health care facility that provides a foundation to support interplanetary travel. As man's experience in space continues to grow so will the ability to provide advanced health care for Earth-orbital and exploratory missions as well.
Relativistic algebraic spinors and quantum motions in phase space
Holland, P.R.
1986-08-01
Following suggestions of Schonberg and Bohm, we study the tensorial phase space representation of the Dirac and Feynman-Gell-Mann equations in terms of the complex Dirac algebra C/sub 4/, a Jordan-Wigner algebra G/sub 4/, and Wigner transformations. To do this we solve the problem of the conditions under which elements in C/sub 4/ generate minimal ideals, and extend this to G/sub 4/. This yields the linear theory of Dirac spin spaces and tensor representations of Dirac spinors, and the spin-1/2 wave equations are represented through fermionic state vectors in a higher space as a set of interconnected tensor relations.
Calculation of a fluctuating entropic force by phase space sampling.
Waters, James T; Kim, Harold D
2015-07-01
A polymer chain pinned in space exerts a fluctuating force on the pin point in thermal equilibrium. The average of such fluctuating force is well understood from statistical mechanics as an entropic force, but little is known about the underlying force distribution. Here, we introduce two phase space sampling methods that can produce the equilibrium distribution of instantaneous forces exerted by a terminally pinned polymer. In these methods, both the positions and momenta of mass points representing a freely jointed chain are perturbed in accordance with the spatial constraints and the Boltzmann distribution of total energy. The constraint force for each conformation and momentum is calculated using Lagrangian dynamics. Using terminally pinned chains in space and on a surface, we show that the force distribution is highly asymmetric with both tensile and compressive forces. Most importantly, the mean of the distribution, which is equal to the entropic force, is not the most probable force even for long chains. Our work provides insights into the mechanistic origin of entropic forces, and an efficient computational tool for unbiased sampling of the phase space of a constrained system. PMID:26274308
On Sasakian hypersurfaces in 6-dimensional Hermitian submanifolds of the Cayley algebra
Banaru, M B
2003-08-31
A criterion for the minimality of a Sasakian hypersurface in a 6-dimensional Hermitian submanifold of the octave algebra is found. It is proved that the type number of a Sasakian hypersurface in a 6-dimensional Hermitian submanifold of the octave algebra is four or five. It is also proved that a Sasakian hypersurface in a 6-dimensional Hermitian submanifold of the Cayley algebra is minimal if and only if it is ruled.
NASA Astrophysics Data System (ADS)
Wünsche, A.
2015-06-01
Starting from the characteristic function of an operator, we investigate cumulant expansions in quantum optics and apply them to two-dimensional distributions for the canonical variables of the phase space in the case of one degree of freedom (Wigner quasiprobability and its Fourier transform, uncertainty matrix) and to one-dimensional distributions (phase operator, time evolution operator to Hamiltonian). In the relations between cumulants and moments, we make emphasis on the central moments of an operator. It is shown that the determinant of the uncertainty matrix (modified uncertainty product) is invariant with respect to rotation and squeezing of the state in the phase space, whereas the uncertainty sum is only invariant with respect to rotations. We examine some problems for exponentials of the phase operator and show how mean values and variances are connected with the cumulants. The Hilbert-Schmidt distance of a state during time evolution to an initial state is discussed by cumulants.
Deep Space Habitat Team: HEFT Phase 2 Effects
NASA Technical Reports Server (NTRS)
Toups, Larry D.; Smitherman, David; Shyface, Hilary; Simon, Matt; Bobkill, Marianne; Komar, D. R.; Guirgis, Peggy; Bagdigian, Bob; Spexarth, Gary
2011-01-01
HEFT was a NASA-wide team that performed analyses of architectures for human exploration beyond LEO, evaluating technical, programmatic, and budgetary issues to support decisions at the highest level of the agency in HSF planning. HEFT Phase I (April - September, 2010) and Phase II (September - December, 2010) examined a broad set of Human Exploration of Near Earth Objects (NEOs) Design Reference Missions (DRMs), evaluating such factors as elements, performance, technologies, schedule, and cost. At end of HEFT Phase 1, an architecture concept known as DRM 4a represented the best available option for a full capability NEO mission. Within DRM4a, the habitation system was provided by Deep Space Habitat (DSH), Multi-Mission Space Exploration Vehicle (MMSEV), and Crew Transfer Vehicle (CTV) pressurized elements. HEFT Phase 2 extended DRM4a, resulting in DRM4b. Scrubbed element-level functionality assumptions and mission Concepts of Operations. Habitation Team developed more detailed concepts of the DSH and the DSH/MMSEV/CTV Conops, including functionality and accommodations, mass & volume estimates, technology requirements, and DDT&E costs. DRM 5 represented an effort to reduce cost by scaling back on technologies and eliminating the need for the development of an MMSEV.
Grassmann phase space methods for fermions. I. Mode theory
NASA Astrophysics Data System (ADS)
Dalton, B. J.; Jeffers, J.; Barnett, S. M.
2016-07-01
In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggest the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics. The theory of Grassmann phase space methods for fermions based on separate modes is developed, showing how the distribution function is defined and used to determine quantum correlation functions, Fock state populations and coherences via Grassmann phase space integrals, how the Fokker-Planck equations are obtained and then converted into equivalent Ito equations for stochastic Grassmann variables. The fermion distribution function is an even Grassmann function, and is unique. The number of c-number Wiener increments involved is 2n2, if there are n modes. The situation is somewhat different to the bosonic c-number case where only 2 n Wiener increments are involved, the sign of the drift term in the Ito equation is reversed and the diffusion matrix in the Fokker-Planck equation is anti-symmetric rather than symmetric. The un-normalised B distribution is of particular importance for determining Fock state populations and coherences, and as pointed out by Plimak, Collett and Olsen, the drift vector in its Fokker-Planck equation only depends linearly on the Grassmann variables. Using this key feature we show how the Ito stochastic equations can be solved numerically for finite times in terms of c-number stochastic
Phase space analysis of bulk viscous matter dominated universe
NASA Astrophysics Data System (ADS)
Sasidharan, Athira; Mathew, Titus K.
2016-06-01
We consider a Friedmann model of the universe with bulk viscous matter and radiation as the cosmic components. We study the asymptotic properties in the equivalent phase space by considering the three cases for the bulk viscous coefficient as (i) ζ = ζ 0, a constant (ii) ζ ={ζ}_0+{ζ}_1overset{\\cdot /a}{a} , depending on velocity of the expansion of the universe and (iii) ζ ={ζ}_0+{ζ}_1overset{\\cdot /a}{a}+{ζ}_2overset{\\cdot \\cdot /a}{overset{\\cdot }{a}} , depending both on velocity and acceleration of the expansion of the universe. It is found that all the three cases predicts the late acceleration of the universe. However, a conventional realistic behaviour of the universe, i.e., a universe having an initial radiation dominated phase, followed by decelerated matter dominated phase and then finally evolving to accelerated epoch, is shown only when ζ = ζ 0, a constant. For the other two cases, it does not show either a prior conventional radiation dominated phase or a matter dominated phase of the universe.
Linearization of the longitudinal phase space without higher harmonic field
NASA Astrophysics Data System (ADS)
Zeitler, Benno; Floettmann, Klaus; Grüner, Florian
2015-12-01
Accelerator applications like free-electron lasers, time-resolved electron diffraction, and advanced accelerator concepts like plasma acceleration desire bunches of ever shorter longitudinal extent. However, apart from space charge repulsion, the internal bunch structure and its development along the beam line can limit the achievable compression due to nonlinear phase space correlations. In order to improve such a limited longitudinal focus, a correction by properly linearizing the phase space is required. At large scale facilities like Flash at Desy or the European Xfel, a higher harmonic cavity is installed for this purpose. In this paper, another method is described and evaluated: Expanding the beam after the electron source enables a higher order correction of the longitudinal focus by a subsequent accelerating cavity which is operated at the same frequency as the electron gun. The elaboration of this idea presented here is based on a ballistic bunching scheme, but can be extended to bunch compression based on magnetic chicanes. The core of this article is an analytic model describing this approach, which is verified by simulations, predicting possible bunch length below 1 fs at low bunch charge. Minimizing the energy spread down to σE/E <1 0-5 while keeping the bunch long is another interesting possibility, which finds applications, e.g., in time resolved transmission electron microscopy concepts.
Tomographic measurement of the phase space distribution of a space-charge-dominated beam
NASA Astrophysics Data System (ADS)
Stratakis, Diktys
Many applications of accelerators, such as free electron lasers, pulsed neutron sources, and heavy ion fusion, require a good quality beam with high intensity. In practice, the achievable intensity is often limited by the dynamics at the low-energy, space-charge dominated end of the machine. Because low-energy beams can have complex distribution functions, a good understanding of their detailed evolution is needed. To address this issue, we have developed a simple and accurate tomographic method to map the beam phase using quadrupole magnets, which includes the effects from space charge. We extend this technique to use also solenoidal magnets which are commonly used at low energies, especially in photoinjectors, thus making the diagnostic applicable to most machines. We simulate our technique using a particle in cell code (PIC), to ascertain accuracy of the reconstruction. Using this diagnostic we report a number of experiments to study and optimize injection, transport and acceleration of intense space charge dominated beams. We examine phase mixing, by studying the phase-space evolution of an intense beam with a transversely nonuniform initial density distribution. Experimental measurements, theoretical predictions and PIC simulations are in good agreement each other. Finally, we generate a parabolic beam pulse to model those beams from photoinjectors, and combine tomography with fast imaging techniques to investigate the time-sliced parameters of beam current, size, energy spread and transverse emittance. We found significant differences between the slice emittance profiles and slice orientation as the beam propagates downstream. The combined effect of longitudinal nonuniform profiles and fast imaging of the transverse phase space provided us with information about correlations between longitudinal and transverse dynamics that we report within this dissertation.
Method of phase space beam dilution utilizing bounded chaos generated by rf phase modulation
NASA Astrophysics Data System (ADS)
Pham, Alfonse N.; Lee, S. Y.; Ng, K. Y.
2015-12-01
This paper explores the physics of chaos in a localized phase-space region produced by rf phase modulation applied to a double rf system. The study can be exploited to produce rapid particle bunch broadening exhibiting longitudinal particle distribution uniformity. Hamiltonian models and particle-tracking simulations are introduced to understand the mechanism and applicability of controlled particle diffusion. When phase modulation is applied to the double rf system, regions of localized chaos are produced through the disruption and overlapping of parametric resonant islands and configured to be bounded by well-behaved invariant tori to prevent particle loss. The condition of chaoticity and the degree of particle dilution can be controlled by the rf parameters. The method has applications in alleviating adverse space-charge effects in high-intensity beams, particle bunch distribution uniformization, and industrial radiation-effects experiments.
Multimegawatt space nuclear power supply, Phase 1 Final report
Not Available
1989-02-17
This Specification establishes the performance, design, development, and test requirements for the Boeing Multimegawatt Space Nuclear Power System (MSNPS). The Boeing Multimegawatt Space Power System is part of the DOE/SDIO Multimegawatt Space Nuclear Power Program. The purpose of this program is to provide a space-based nuclear power system to meet the needs of SDIO missions. The Boeing MSNPS is a category 1 concept which is capable of delivering 10's of MW(e) for 100's of seconds with effluent permitted. A design goal is for the system to have growth or downscale capability for other power system concepts. The growth objective is to meet the category 3 capability of 100's of MW(e) for 100's of seconds, also with effluent permitted. The purpose of this preliminary document is to guide the conceptual design effort throughout the Phase 1 study effort. This document will be updated through out the study. It will thus result in a record of the development of the design effort.
Phase space analysis of multipactor saturation in rectangular waveguide
NASA Astrophysics Data System (ADS)
Lingwood, C. J.; Burt, G.; Dexter, A. C.; Smith, J. D. A.; Goudket, P.; Stoltz, P. H.
2012-03-01
In certain high power RF systems multipactor cannot be avoided for all operating points, but its existence places limits on performance, efficiency, lifetime, and reliability. As an example multipactor in the input couplers of superconducting RF cavities can be a major limitation to the maximum RF power. Several studies have concentrated on rectangular waveguide input couplers which are used in many light sources. Most of these studies neglect space charge assuming that the effect of space charge is simply to defocus the electron bunches. Modelling multipactor to saturation is of interest in determining the performance of waveguide under a range of conditions. Particle-in-cell modelling including space charge has been performed for 500 MHz half-height rectangular waveguide. Phase plots of electron trajectories can aid understanding the processes taking place in the multipactor. Results strongly suggest that the multipacting trajectories are strongly perturbed by space charge causing the electrons to transition from two-surface to single-surface trajectories as the multipactor approaches saturation.
A gauge theory of gravity in curved phase-spaces
NASA Astrophysics Data System (ADS)
Castro, Carlos
2016-06-01
After a cursory introduction of the basic ideas behind Born’s Reciprocal Relativity theory, the geometry of the cotangent bundle of spacetime is studied via the introduction of nonlinear connections associated with certain nonholonomic modifications of Riemann-Cartan gravity within the context of Finsler geometry. A novel gauge theory of gravity in the 8D cotangent bundle T∗M of spacetime is explicitly constructed and based on the gauge group SO(6, 2) ×sR8 which acts on the tangent space to the cotangent bundle T(x,p)T∗M at each point (x,p). Several gravitational actions involving curvature and torsion tensors and associated with the geometry of curved phase-spaces are presented. We conclude with a brief discussion of the field equations, the geometrization of matter, quantum field theory (QFT) in accelerated frames, T-duality, double field theory, and generalized geometry.
Values of the phase space factors for double beta decay
Stoica, Sabin Mirea, Mihai
2015-10-28
We report an up-date list of the experimentally most interesting phase space factors for double beta decay (DBD). The electron/positron wave functions are obtained by solving the Dirac equations with a Coulomb potential derived from a realistic proton density distribution in nucleus and with inclusion of the finite nuclear size (FNS) and electron screening (ES) effects. We build up new numerical routines which allow us a good control of the accuracy of calculations. We found several notable differences as compared with previous results reported in literature and possible sources of these discrepancies are discussed.
Testing gravity with the stacked phase space around galaxy clusters.
Lam, Tsz Yan; Nishimichi, Takahiro; Schmidt, Fabian; Takada, Masahiro
2012-08-01
In general relativity, the average velocity field of dark matter around galaxy clusters is uniquely determined by the mass profile. The latter can be measured through weak lensing. We propose a new method of measuring the velocity field (phase space density) by stacking redshifts of surrounding galaxies from a spectroscopic sample. In combination with lensing, this yields a direct test of gravity on scales of 1-30 Mpc. Using N-body simulations, we show that this method can improve upon current constraints on f(R) and Dvali-Gabadadze-Porrati model parameters by several orders of magnitude when applied to upcoming imaging and redshift surveys. PMID:23006162
Space shuttle phase B. Volume 2: Technical summary, addendum A
NASA Technical Reports Server (NTRS)
1971-01-01
A study was conducted to analyze the characteristics and performance data for the booster vehicles to be used with the space shuttle operations. It was determined that the single pressure-fed booster offered the lowest program cost per flight of the pressure-fed booster arrangements studied. The fly back booster required the highest peak annual funding and highest program cost. It was recommended that the pressure-fed booster, series burn with liquid oxygen phase, be continued for further study. The flyback booster study was discontinued. Both solid and liquid propelled booster vehicles with 14 by 45 foot and 15 by 60 foot payload orbiters were considered.
Advanced microelectronics research for space applications, phase 2
NASA Technical Reports Server (NTRS)
Gaertner, W. W.
1971-01-01
Negative-resistance circuits with possible space flight applications are discussed. The basic design approach is to use impedance rotation, i.e., the conversion from capacitance to negative resistance, and from resistance to inductance by the phase shift of the transistor current gain at high frequencies. The subjects discussed in detail are the following: hybrid fabrication of VHF and UHF negative-resistance stages with lumped passive elements; formulation of measurement techniques to characterize transistors and to extend the frequency of negative-resistance transistor amplifiers to higher microwave frequencies; and derivation of transistor characteristics required to increase the frequency range of negative-resistance transistor stages.
Efficient computations of quantum canonical Gibbs state in phase space
NASA Astrophysics Data System (ADS)
Bondar, Denys I.; Campos, Andre G.; Cabrera, Renan; Rabitz, Herschel A.
2016-06-01
The Gibbs canonical state, as a maximum entropy density matrix, represents a quantum system in equilibrium with a thermostat. This state plays an essential role in thermodynamics and serves as the initial condition for nonequilibrium dynamical simulations. We solve a long standing problem for computing the Gibbs state Wigner function with nearly machine accuracy by solving the Bloch equation directly in the phase space. Furthermore, the algorithms are provided yielding high quality Wigner distributions for pure stationary states as well as for Thomas-Fermi and Bose-Einstein distributions. The developed numerical methods furnish a long-sought efficient computation framework for nonequilibrium quantum simulations directly in the Wigner representation.
The Simpsons program 6-D phase space tracking with acceleration
NASA Astrophysics Data System (ADS)
Machida, S.
1993-12-01
A particle tracking code, Simpsons, in 6-D phase space including energy ramping has been developed to model proton synchrotrons and storage rings. We take time as the independent variable to change machine parameters and diagnose beam quality in a quite similar way as real machines, unlike existing tracking codes for synchrotrons which advance a particle element by element. Arbitrary energy ramping and rf voltage curves as a function of time are read as an input file for defining a machine cycle. The code is used to study beam dynamics with time dependent parameters. Some of the examples from simulations of the Superconducting Super Collider (SSC) boosters are shown.
Spatial coherence wavelets and phase-space representation of diffraction.
Castañeda, Román; Carrasquilla, Juan
2008-08-01
The phase-space representation of the Fresnel-Fraunhofer diffraction of optical fields in any state of spatial coherence is based on the marginal power spectrum carried by the spatial coherence wavelets. Its structure is analyzed in terms of the classes of source pairs and the spot of the field, which is treated as the hologram of the map of classes. Negative values of the marginal power spectrum are interpreted as negative energies. The influence of the aperture edge on diffraction is stated in terms of the distortion of the supports of the complex degree of spatial coherence near it. Experimental results are presented. PMID:18670545
Phase space view of quantum mechanical systems and Fisher information
NASA Astrophysics Data System (ADS)
Nagy, Á.
2016-06-01
Pennini and Plastino showed that the form of the Fisher information generated by the canonical distribution function reflects the intrinsic structure of classical mechanics. Now, a quantum mechanical generalization of the Pennini-Plastino theory is presented based on the thermodynamical transcription of the density functional theory. Comparing to the classical case, the phase-space Fisher information contains an extra term due to the position dependence of the temperature. However, for the special case of constant temperature, the expression derived bears resemblance to the classical one. A complete analogy to the classical case is demonstrated for the linear harmonic oscillator.
Phase-space rotations and orbital Stokes parameters.
Alieva, Tatiana; Bastiaans, Martin J
2009-02-15
We introduce the orbital Stokes parameters as a linear combination of a beam's second-order moments. Similar to the ones describing the field polarization and associated with beam energy and its spin angular momentum, the orbital Stokes parameters are related to the total beam width and its orbital angular momentum. We derive the transformation laws for these parameters during beam propagation through first-order optical systems associated with phase-space rotations. The values of the orbital Stokes parameters for Gaussian modes and arbitrary fields expressed as their linear superposition are obtained. PMID:19373324
The Helmholtz Hierarchy: phase space statistics of cold dark matter
Tassev, Svetlin V.
2011-10-01
We present a new formalism to study large-scale structure in the universe. The result is a hierarchy (which we call the ''Helmholtz Hierarchy'') of equations describing the phase space statistics of cold dark matter (CDM). The hierarchy features a physical ordering parameter which interpolates between the Zel'dovich approximation and fully-fledged gravitational interactions. The results incorporate the effects of stream crossing. We show that the Helmholtz hierarchy is self-consistent and obeys causality to all orders. We present an interpretation of the hierarchy in terms of effective particle trajectories.
Nonlinear bulk viscosity in FRW cosmology: a phase space analysis.
NASA Astrophysics Data System (ADS)
Acquaviva, G.; Beesham, A.
2015-11-01
We consider a Friedmann-Robertson-Walker spacetime filled with both viscous radiation and nonviscous dust. The former has a bulk viscosity that is proportional to an arbitrary power of the energy density, i.e. \\zeta \\propto {ρ }{{v}}ν , and viscous pressure satisfying a nonlinear evolution equation. The analysis is carried out in the context of dynamical systems and the properties of solutions corresponding to the fixed points are discussed. For some ranges of the relevant parameter ν we find that the trajectories in the phase space evolve from a FRW singularity towards an asymptotic de Sitter attractor, confirming and extending previous analysis in the literature.
Dynamical Evolution of Quintessence Cosmology in a Physical Phase Space
NASA Astrophysics Data System (ADS)
Qi, Jing-Zhao; Zhang, Ming-Jian; Liu, Wen-Biao
2016-04-01
The phase space analysis of cosmological parameters Ω ϕ and γ ϕ is given. Based on this, the well-known quintessence cosmology is studied with an exponential potential V(φ )=V0exp (-λ φ ). Given observational data, the current state of universe could be pinpointed in the phase diagrams, thus making the diagrams more informative. The scaling solution of quintessence usually is not supposed to give the cosmic accelerating expansion, but we prove it could educe the transient acceleration. We also find that the differential equations of system used widely in study of scalar field are incomplete, and then a numerical method is used to figure out the range of application.
Dynamical Evolution of Quintessence Cosmology in a Physical Phase Space
NASA Astrophysics Data System (ADS)
Qi, Jing-Zhao; Zhang, Ming-Jian; Liu, Wen-Biao
2016-08-01
The phase space analysis of cosmological parameters Ω ϕ and γ ϕ is given. Based on this, the well-known quintessence cosmology is studied with an exponential potential V(φ )=V0exp (-λ φ ). Given observational data, the current state of universe could be pinpointed in the phase diagrams, thus making the diagrams more informative. The scaling solution of quintessence usually is not supposed to give the cosmic accelerating expansion, but we prove it could educe the transient acceleration. We also find that the differential equations of system used widely in study of scalar field are incomplete, and then a numerical method is used to figure out the range of application.
Solution of phase space diffusion equations using interacting trajectory ensembles
NASA Astrophysics Data System (ADS)
Donoso, Arnaldo; Martens, Craig C.
2002-06-01
In this paper, we present a new method for simulating the evolution of the phase space distribution function describing a system coupled to a Markovian thermal bath. The approach is based on the propagation of ensembles of trajectories. Instead of incorporating environmental perturbations as stochastic forces, however, the present method includes these effects by additional deterministic interactions between the ensemble members. The general formalism is developed and tested on model systems describing one-dimensional diffusion, relaxation of a coherently excited harmonic oscillator coupled to a thermal bath, and activated barrier crossing in a bistable potential. Excellent agreement with exact results or approximate theories is obtained in all cases. The method provides an entirely deterministic trajectory-based approach to the solution of condensed phase dynamics and chemical reactions.
Phase space lattices and integrable nonlinear wave equations
NASA Astrophysics Data System (ADS)
Tracy, Eugene; Zobin, Nahum
2003-10-01
Nonlinear wave equations in fluids and plasmas that are integrable by Inverse Scattering Theory (IST), such as the Korteweg-deVries and nonlinear Schrodinger equations, are known to be infinite-dimensional Hamiltonian systems [1]. These are of interest physically because they predict new phenomena not present in linear wave theories, such as solitons and rogue waves. The IST method provides solutions of these equations in terms of a special class of functions called Riemann theta functions. The usual approach to the theory of theta functions tends to obscure the underlying phase space structure. A theory due to Mumford and Igusa [2], however shows that the theta functions arise naturally in the study of phase space lattices. We will describe this theory, as well as potential applications to nonlinear signal processing and the statistical theory of nonlinear waves. 1] , S. Novikov, S. V. Manakov, L. P. Pitaevskii and V. E. Zakharov, Theory of solitons: the inverse scattering method (Consultants Bureau, New York, 1984). 2] D. Mumford, Tata lectures on theta, Vols. I-III (Birkhauser); J. Igusa, Theta functions (Springer-Verlag, New York, 1972).
Fast-phase space computation of multiple arrivals
Fomel, S.; Sethian, J. A.
2002-01-01
We present a fast, general computational technique for computing the phase-space solution of static Hamilton–Jacobi equations. Starting with the Liouville formulation of the characteristic equations, we derive “Escape Equations” which are static, time-independent Eulerian PDEs. They represent all arrivals to the given boundary from all possible starting configurations. The solution is numerically constructed through a “one-pass” formulation, building on ideas from semi-Lagrangian methods, Dijkstra-like methods for the Eikonal equation, and Ordered Upwind Methods. To compute all possible trajectories corresponding to all possible boundary conditions, the technique is of computational order O(N log N), where N is the total number of points in the computational phase-space domain; any particular set of boundary conditions then is extracted through rapid post-processing. Suggestions are made for speeding up the algorithm in the case when the particular distribution of sources is provided in advance. As an application, we apply the technique to the problem of computing first, multiple, and most energetic arrivals to the Eikonal equation. PMID:12032282
An Absolute Phase Space for the Physicality of Matter
NASA Astrophysics Data System (ADS)
Valentine, John S.
2010-12-01
We define an abstract and absolute phase space ("APS") for sub-quantum intrinsic wave states, in three axes, each mapping directly to a duality having fundamental ontological basis. Many aspects of quantum physics emerge from the interaction algebra and a model deduced from principles of `unique solvability' and `identifiable entity', and we reconstruct previously abstract fundamental principles and phenomena from these new foundations. The physical model defines bosons as virtual continuous waves pairs in the APS, and fermions as real self-quantizing snapshots of those waves when simple conditions are met. The abstraction and physical model define a template for the constitution of all fermions, a template for all the standard fundamental bosons and their local interactions, in a common framework and compactified phase space for all forms of real matter and virtual vacuum energy, and a distinct algebra for observables and unobservables. To illustrate our scheme's potential, we provide examples of slit experiment variations (where the model finds theoretical basis for interference only occurring between two final sources), QCD (where we may model most attributes known to QCD, and a new view on entanglement), and we suggest approaches for other varied applications. We believe this is a viable candidate for further exploration as a foundational proposition for physics.
An Absolute Phase Space for the Physicality of Matter
Valentine, John S.
2010-12-22
We define an abstract and absolute phase space (''APS'') for sub-quantum intrinsic wave states, in three axes, each mapping directly to a duality having fundamental ontological basis. Many aspects of quantum physics emerge from the interaction algebra and a model deduced from principles of 'unique solvability' and 'identifiable entity', and we reconstruct previously abstract fundamental principles and phenomena from these new foundations. The physical model defines bosons as virtual continuous waves pairs in the APS, and fermions as real self-quantizing snapshots of those waves when simple conditions are met. The abstraction and physical model define a template for the constitution of all fermions, a template for all the standard fundamental bosons and their local interactions, in a common framework and compactified phase space for all forms of real matter and virtual vacuum energy, and a distinct algebra for observables and unobservables. To illustrate our scheme's potential, we provide examples of slit experiment variations (where the model finds theoretical basis for interference only occurring between two final sources), QCD (where we may model most attributes known to QCD, and a new view on entanglement), and we suggest approaches for other varied applications. We believe this is a viable candidate for further exploration as a foundational proposition for physics.
Coherent quantum squeezing due to the phase space noncommutativity
NASA Astrophysics Data System (ADS)
Bernardini, Alex E.; Mizrahi, Salomon S.
2015-06-01
The effects of general noncommutativity of operators on producing deformed coherent squeezed states is examined in phase space. A two-dimensional noncommutative (NC) quantum system supported by a deformed mathematical structure, similar to that of Hadamard billiard, is obtained and the components behaviour is monitored in time. It is assumed that the independent degrees of freedom are two free 1D harmonic oscillators (HOs), so the system Hamiltonian does not contain interaction terms. Through the NC deformation parameterized by a Seiberg-Witten transform on the original canonical variables, one gets the standard commutation relations for the new ones, such that the obtained, new, Hamiltonian represents two interacting 1D HOs. By admitting that one HO is inverted relatively to the other, we show that their effective interaction induces a squeezing dynamics for initial coherent states imaged in the phase space. A suitable pattern of logarithmic spirals is obtained and some relevant properties are discussed in terms of Wigner functions, which are essential to put in evidence the effects of the noncommutativity.
Fast-phase space computation of multiple arrivals.
Fomel, S; Sethian, J A
2002-05-28
We present a fast, general computational technique for computing the phase-space solution of static Hamilton-Jacobi equations. Starting with the Liouville formulation of the characteristic equations, we derive "Escape Equations" which are static, time-independent Eulerian PDEs. They represent all arrivals to the given boundary from all possible starting configurations. The solution is numerically constructed through a "one-pass" formulation, building on ideas from semi-Lagrangian methods, Dijkstra-like methods for the Eikonal equation, and Ordered Upwind Methods. To compute all possible trajectories corresponding to all possible boundary conditions, the technique is of computational order O(N log N), where N is the total number of points in the computational phase-space domain; any particular set of boundary conditions then is extracted through rapid post-processing. Suggestions are made for speeding up the algorithm in the case when the particular distribution of sources is provided in advance. As an application, we apply the technique to the problem of computing first, multiple, and most energetic arrivals to the Eikonal equation. PMID:12032282
Laser Interferometer Space Antenna (LISA) Far Field Phase Patterns
NASA Technical Reports Server (NTRS)
Waluschka, Eugene; Obenschain, Arthur F. (Technical Monitor)
2000-01-01
The Laser Interferometer Space Antenna (LISA) consists of three spacecraft in orbit about the sun. The orbits are chosen such that the three spacecraft are always at (roughly) the vertices of a equilateral triangle with 5 million kilometer leg lengths. Even though the distances between the three spacecraft are 5 million kilometers, the expected phase shifts between any two beams, due to a gravitational wave, only correspond to a distance change of about 10 pico meters, which is about 10(exp -5) waves for a laser wavelength of 1064 nm. To obtain the best signal-to-noise ratio, noise sources such as changes in the apparent distances due to pointing jitter must be controlled carefully. This is the main reason for determining the far-field phase patterns of a LISA type telescope. Because of torque on the LISA spacecraft and other disturbances, continuous adjustments to the pointing of the telescopes are required. These pointing adjustments will be a "jitter" source. If the transmitted wave is perfectly spherical then rotations (Jitter) about its geometric center will not produce any effect at the receiving spacecraft. However, if the outgoing wave is not perfectly spherical, then pointing jitter will produce a phase variation at the receiving spacecraft. The following sections describe the "brute force" computational approach used to determine the scalar wave front as a function of exit pupil (Zernike) aberrations and to show the results (mostly graphically) of the computations. This approach is straightforward and produces believable phase variations to sub-pico meter accuracy over distances on the order of 5 million kilometers. As such this analyzes the far field phase sensitivity to exit pupil aberrations.
Volumic omit maps in ab initio dual-space phasing.
Oszlányi, Gábor; Sütő, András
2016-07-01
Alternating-projection-type dual-space algorithms have a clear construction, but are susceptible to stagnation and, thus, inefficient for solving the phase problem ab initio. To improve this behaviour new omit maps are introduced, which are real-space perturbations applied periodically during the iteration process. The omit maps are called volumic, because they delete some predetermined subvolume of the unit cell without searching for atomic regions or analysing the electron density in any other way. The basic algorithms of positivity, histogram matching and low-density elimination are tested by their solution statistics. It is concluded that, while all these algorithms based on weak constraints are practically useless in their pure forms, appropriate volumic omit maps can transform them to practically useful methods. In addition, the efficiency of the already useful reflector-type charge-flipping algorithm can be further improved. It is important that these results are obtained by using non-sharpened structure factors and without any weighting scheme or reciprocal-space perturbation. The mathematical background of volumic omit maps and their expected applications are also discussed. PMID:27357850
Constraining neutron guide optimizations with phase-space considerations
NASA Astrophysics Data System (ADS)
Bertelsen, Mads; Lefmann, Kim
2016-09-01
We introduce a method named the Minimalist Principle that serves to reduce the parameter space for neutron guide optimization when the required beam divergence is limited. The reduced parameter space will restrict the optimization to guides with a minimal neutron intake that are still theoretically able to deliver the maximal possible performance. The geometrical constraints are derived using phase-space propagation from moderator to guide and from guide to sample, while assuming that the optimized guides will achieve perfect transport of the limited neutron intake. Guide systems optimized using these constraints are shown to provide performance close to guides optimized without any constraints, however the divergence received at the sample is limited to the desired interval, even when the neutron transport is not limited by the supermirrors used in the guide. As the constraints strongly limit the parameter space for the optimizer, two control parameters are introduced that can be used to adjust the selected subspace, effectively balancing between maximizing neutron transport and avoiding background from unnecessary neutrons. One parameter is needed to describe the expected focusing abilities of the guide to be optimized, going from perfectly focusing to no correlation between position and velocity. The second parameter controls neutron intake into the guide, so that one can select exactly how aggressively the background should be limited. We show examples of guides optimized using these constraints which demonstrates the higher signal to noise than conventional optimizations. Furthermore the parameter controlling neutron intake is explored which shows that the simulated optimal neutron intake is close to the analytically predicted, when assuming that the guide is dominated by multiple scattering events.
NASA Astrophysics Data System (ADS)
Trahan, Corey J.; Wyatt, Robert E.
2003-10-01
Recently, Donoso and Martens described a method for evolving both classical and quantum phase-space distribution functions, W(q,p,t), that involves the propagation of an ensemble of correlated trajectories. The trajectories are linked into a unified whole by spatial and momentum derivatives of density dependent terms in the equations of motion. On each time step, these nonlocal terms were evaluated by fitting the density around each trajectory to an assumed functional form. In the present study, we develop a different trajectory method for propagating phase-space distribution functions. A hierarchy of coupled analytic equations of motion are derived for the q and p derivatives of the density and a truncated set of these are integrated along each trajectory concurrently with the equation of motion for the density. The advantage of this approach is that individual trajectories can be propagated, one at a time, and function fitting is not required to evaluate the nonlocal terms. Regional nonlocality can be incorporated at various levels of approximation to "dress" what would otherwise be "thin" locally propagating trajectories. This derivative propagation method is used to obtain trajectory solutions for the Klein-Kramers equation, the Husimi equation, and for a smoothed version of the Caldeira-Leggett equation derived by the Diosi. Trajectory solutions are obtained for the relaxation of an oscillator in contact with a thermal bath and for the decay of a metastable state.
A phase-space beam position monitor for synchrotron radiation
Samadi, Nazanin; Bassey, Bassey; Martinson, Mercedes; Belev, George; Dallin, Les; de Jong, Mark; Chapman, Dean
2015-01-01
The stability of the photon beam position on synchrotron beamlines is critical for most if not all synchrotron radiation experiments. The position of the beam at the experiment or optical element location is set by the position and angle of the electron beam source as it traverses the magnetic field of the bend-magnet or insertion device. Thus an ideal photon beam monitor would be able to simultaneously measure the photon beam’s position and angle, and thus infer the electron beam’s position in phase space. X-ray diffraction is commonly used to prepare monochromatic beams on X-ray beamlines usually in the form of a double-crystal monochromator. Diffraction couples the photon wavelength or energy to the incident angle on the lattice planes within the crystal. The beam from such a monochromator will contain a spread of energies due to the vertical divergence of the photon beam from the source. This range of energies can easily cover the absorption edge of a filter element such as iodine at 33.17 keV. A vertical profile measurement of the photon beam footprint with and without the filter can be used to determine the vertical centroid position and angle of the photon beam. In the measurements described here an imaging detector is used to measure these vertical profiles with an iodine filter that horizontally covers part of the monochromatic beam. The goal was to investigate the use of a combined monochromator, filter and detector as a phase-space beam position monitor. The system was tested for sensitivity to position and angle under a number of synchrotron operating conditions, such as normal operations and special operating modes where the photon beam is intentionally altered in position and angle at the source point. The results are comparable with other methods of beam position measurement and indicate that such a system is feasible in situations where part of the synchrotron beam can be used for the phase-space measurement. PMID:26134798
Tailoring phase-space in neutron beam extraction
NASA Astrophysics Data System (ADS)
Weichselbaumer, S.; Brandl, G.; Georgii, R.; Stahn, J.; Panzner, T.; Böni, P.
2015-09-01
In view of the trend towards smaller samples and experiments under extreme conditions it is important to deliver small and homogeneous neutron beams to the sample area. For this purpose, elliptic and/or Montel mirrors are ideally suited as the phase space of the neutrons can be defined far away from the sample. Therefore, only the useful neutrons will arrive at the sample position leading to a very low background. We demonstrate the ease of designing neutron transport systems using simple numeric tools, which are verified using Monte-Carlo simulations that allow taking into account effects of gravity and finite beam size. It is shown that a significant part of the brilliance can be transferred from the moderator to the sample. Our results may have a serious impact on the design of instruments at spallation sources such as the European Spallation Source (ESS) in Lund, Sweden.
Capture into resonance and phase space dynamics in optical centrifuge
NASA Astrophysics Data System (ADS)
Armon, Tsafrir; Friedland, Lazar
2016-05-01
The process of capture of a molecular enesemble into rotational resonance in the optical centrifuge is investigated. The adiabaticity and phase space incompressibility are used to find the resonant capture probability in terms of two dimensionless parameters P1 , 2 characterising the driving strength and the nonlinearity, and related to three characteristic time scales in the problem. The analysis is based on the transformation to action-angle variables and the single resonance approximation, yielding reduction of the three-dimensional rotation problem to one degree of freedom. The analytic results for capture probability are in a good agreement with simulations. The existing experiments satisfy the validity conditions of the theory. This work was supported by the Israel Science Foundation Grant 30/14.
Nonclassicality indicator for the real phase-space distribution functions
Sadeghi, Parvin; Khademi, Siamak; Nasiri, Sadollah
2010-07-15
Benedict et al. and Kenfack et al. advocated nonclassicality indicators based on the measurement of negativity of the Wigner distribution functions. These indicators have some applications in quantum mechanics and quantum optics. In this paper we define a nonclassicality indicator in terms of the interference in phase space, which is applicable to some real distribution functions including those of Wigner. As a special case one may reproduce the previous results using our indicator for the Wigner distribution functions. This indicator is examined for cases of the Schroedinger cat state and the thermal states and the results are compared with those obtained by previous methods. It seems that the physical behavior of nonclassicality indicators originates in the uncertainty principle. This is shown by an onto correspondence between these indicators and the uncertainty principle.
Space shuttle electromagnetic environment experiment. Phase A: Definition study
NASA Technical Reports Server (NTRS)
Haber, F.; Showers, R. M.; Taheri, S. H.; Forrest, L. A., Jr.; Kocher, C.
1974-01-01
A program is discussed which develops a concept for measuring the electromagnetic environment on earth with equipment on board an orbiting space shuttle. Earlier work on spaceborne measuring experiments is reviewed, and emissions to be expected are estimated using, in part, previously gathered data. General relations among system parameters are presented, followed by a proposal on spatial and frequency scanning concepts. The methods proposed include a nadir looking measurement with small lateral scan and a circularly scanned measurement looking tangent to the earth's surface at the horizon. Antenna requirements are given, assuming frequency coverage from 400 MHz to 40 GHz. For the low frequency range, 400-1000 MHz, a processed, thinned array is proposed which will be more fully analyzed in the next phase of the program. Preliminary hardware and data processing requirements are presented.
Production of Coherent Phase Space Islands in Trapped Plasma
NASA Astrophysics Data System (ADS)
Hunter, Eric; Povilus, Alex; Belmore, Nathan; Lewis, Nicole; Shanman, Sabrina; Fajans, Joel
2015-11-01
Particles are coherently extracted from a cold Maxwellian distribution into phase space islands by applying a fixed-frequency RF drive while the plasma bounce frequency is swept downward by lowering the potential confining the plasma. These objects can appear spontaneously in pure electron and mixed ion plasma experiments during particle extraction when the noise power spectrum of the confining potential has peaks in the rf band, as is often the case in a laboratory environment. Interestingly, the particles in these islands have been observed to form tight energy distributions, making the mechanism potentially useful for low energy/monoenergetic plasma injection devices. In particular, these features would be useful for antimatter spectroscopy and mixing for antihydrogen formation. This work is supported by DoE, Grant DE-FG02-06ER54904.
Transverse - longitudinal phase-space manipulations and correlations.
Kim, K.-J.; Sessler, A.; Accelerator Systems Division; LBNL
2006-01-01
Manipulations on transverse and longitudinal phase-space distribution of an electron beam are discussed within the constraints imposed by symplectic conditions. A few examples are presented: transverse-longitudinal emittance exchange to improve performance of a high-gain free-electron laser (FEL) for hard x-rays, and the flat beam technique and its application to compact Terahertz devices and ultrashort-pulse generation. It is shown that emittance transfer to some degree would be advantageous for FELs and that introducing correlations would allow just such transfers. Also, it is shown that transverse-longitudinal correlations would be distinctly advantageous for FELs. Conventional and exotic methods of producing such correlations are described. Practical difficulties associated with each of the conventional methods are described, although the nonconventional methods appear to hold promise.
Transverse-Longitudinal Phase-Space Manipulations and Correlations
Kim, Kwang-Je; Sessler, Andrew
2006-03-20
Manipulations on transverse and longitudinal phase-space distribution of an electron beam are discussed within the constraints imposed by symplectic conditions. A few examples are presented: transverse-longitudinal emittance exchange to improve performance of a high-gain free-electron laser (FEL) for hard x-rays, and the flat beam technique and its application to compact Terahertz devices and ultrashort-pulse generation. It is shown that emittance transfer to some degree would be advantageous for FELs and that introducing correlations would allow just such transfers. Also, it is shown that transverse-longitudinal correlations would be distinctly advantageous for FELs. Conventional and exotic methods of producing such correlations are described. Practical difficulties associated with each of the conventional methods are described, although the nonconventional methods appear to hold promise.
Phase-space noncommutative formulation of Ozawa's uncertainty principle
NASA Astrophysics Data System (ADS)
Bastos, Catarina; Bernardini, Alex E.; Bertolami, Orfeu; Costa Dias, Nuno; Prata, João Nuno
2014-08-01
Ozawa's measurement-disturbance relation is generalized to a phase-space noncommutative extension of quantum mechanics. It is shown that the measurement-disturbance relations have additional terms for backaction evading quadrature amplifiers and for noiseless quadrature transducers. Several distinctive features appear as a consequence of the noncommutative extension: measurement interactions which are noiseless, and observables which are undisturbed by a measurement, or of independent intervention in ordinary quantum mechanics, may acquire noise, become disturbed by the measurement, or no longer be an independent intervention in noncommutative quantum mechanics. It is also found that there can be states which violate Ozawa's universal noise-disturbance trade-off relation, but verify its noncommutative deformation.
Wigner phase space distribution via classical adiabatic switching.
Bose, Amartya; Makri, Nancy
2015-09-21
Evaluation of the Wigner phase space density for systems of many degrees of freedom presents an extremely demanding task because of the oscillatory nature of the Fourier-type integral. We propose a simple and efficient, approximate procedure for generating the Wigner distribution that avoids the computational difficulties associated with the Wigner transform. Starting from a suitable zeroth-order Hamiltonian, for which the Wigner density is available (either analytically or numerically), the phase space distribution is propagated in time via classical trajectories, while the perturbation is gradually switched on. According to the classical adiabatic theorem, each trajectory maintains a constant action if the perturbation is switched on infinitely slowly. We show that the adiabatic switching procedure produces the exact Wigner density for harmonic oscillator eigenstates and also for eigenstates of anharmonic Hamiltonians within the Wentzel-Kramers-Brillouin (WKB) approximation. We generalize the approach to finite temperature by introducing a density rescaling factor that depends on the energy of each trajectory. Time-dependent properties are obtained simply by continuing the integration of each trajectory under the full target Hamiltonian. Further, by construction, the generated approximate Wigner distribution is invariant under classical propagation, and thus, thermodynamic properties are strictly preserved. Numerical tests on one-dimensional and dissipative systems indicate that the method produces results in very good agreement with those obtained by full quantum mechanical methods over a wide temperature range. The method is simple and efficient, as it requires no input besides the force fields required for classical trajectory integration, and is ideal for use in quasiclassical trajectory calculations. PMID:26395694
Generalizing the Boltzmann equation in complex phase space.
Zadehgol, Abed
2016-08-01
In this work, a generalized form of the BGK-Boltzmann equation is proposed, where the velocity, position, and time can be represented by real or complex variables. The real representation leads to the conventional BGK-Boltzmann equation, which can recover the continuity and Navier-Stokes equations. We show that the complex representation yields a different set of equations, and it can also recover the conservation and Navier-Stokes equations, at low Mach numbers, provided that the imaginary component of the macroscopic mass can be neglected. We briefly review the Constant Speed Kinetic Model (CSKM), which was introduced in Zadehgol and Ashrafizaadeh [J. Comp. Phys. 274, 803 (2014)JCTPAH0021-999110.1016/j.jcp.2014.06.053] and Zadehgol [Phys. Rev. E 91, 063311 (2015)PLEEE81539-375510.1103/PhysRevE.91.063311]. The CSKM is then used as a basis to show that the complex-valued equilibrium distribution function of the present model can be identified with a simple singularity in the complex phase space. The virtual particles, in the present work, are concentrated on virtual "branes" which surround the computational nodes. Employing the Cauchy integral formula, it is shown that certain variations of the "branes," in the complex phase space, do not affect the local kinetic states. This property of the new model, which is referred to as the "apparent jumps" in the present work, is used to construct new models. The theoretical findings have been tested by simulating three benchmark flows. The results of the present simulations are in excellent agreement with the previous results reported by others. PMID:27627421
Nonlinear instabilities driven by coherent phase-space structures
NASA Astrophysics Data System (ADS)
Lesur, Maxime
2012-10-01
Coherent phase-space (PS) structures are an important feature of plasma turbulence. They can drive nonlinear instabilities [1], intermittency in drift-wave turbulence [2], and transport [3]. We aim at a comprehensive understanding of turbulence, not just as an ensemble of waves, as quasilinear theory implies, but as a mixture of coupled waves and localized structures. This work, which focuses on isolated PS structures, is a fundamental advance in this direction. We analyze the effects of self-binding negative fluctuations (PS holes) on stability, intermittency and anomalous resistivity, both analytically and numerically. We present a new theory which describes the growth of a hole or clump [4]. We find that PS holes grow nonlinearly, independently of linear stability. Numerical simulations clarify the physics of nonlinear instabilities in both subcritical and supercritical conditions. When many resonances are unstable, several holes can coalesce into one main macro-scale structure, which survives much longer than a quasilinear diffusion time, suggesting that it may be crucial to resolve phase-space turbulence in analytical and numerical studies of transport. These findings are applied to two fundamental paradigms of plasma physics: bump-on-tail instabilities in 1D electronic plasma and current-driven ion-acoustic instabilities electron-ion plasma. Our results expose important limits of routinely-used linear and quasilinear theories.[4pt] [1] T.H. Dupree, Phys. Fluids 15, 334 (1972); R.H. Berman et al., Phys. Rev. Lett. 48, 1249 (1982).[0pt] [2] P.W. Terry, P.H. Diamond, and T.S. Hahm, Phys. Fluids B 2, 2048 (1990).[0pt] [3] H. Biglari et al., Phys. Fluids 31, 2644 (1988); Y. Kosuga et al., Phys. Plasmas 18, 122305 (2011).[0pt] [4] M. Lesur, P.H. Diamond, submitted to Phys. Rev. Lett.
Wigner phase space distribution via classical adiabatic switching
Bose, Amartya; Makri, Nancy
2015-09-21
Evaluation of the Wigner phase space density for systems of many degrees of freedom presents an extremely demanding task because of the oscillatory nature of the Fourier-type integral. We propose a simple and efficient, approximate procedure for generating the Wigner distribution that avoids the computational difficulties associated with the Wigner transform. Starting from a suitable zeroth-order Hamiltonian, for which the Wigner density is available (either analytically or numerically), the phase space distribution is propagated in time via classical trajectories, while the perturbation is gradually switched on. According to the classical adiabatic theorem, each trajectory maintains a constant action if the perturbation is switched on infinitely slowly. We show that the adiabatic switching procedure produces the exact Wigner density for harmonic oscillator eigenstates and also for eigenstates of anharmonic Hamiltonians within the Wentzel-Kramers-Brillouin (WKB) approximation. We generalize the approach to finite temperature by introducing a density rescaling factor that depends on the energy of each trajectory. Time-dependent properties are obtained simply by continuing the integration of each trajectory under the full target Hamiltonian. Further, by construction, the generated approximate Wigner distribution is invariant under classical propagation, and thus, thermodynamic properties are strictly preserved. Numerical tests on one-dimensional and dissipative systems indicate that the method produces results in very good agreement with those obtained by full quantum mechanical methods over a wide temperature range. The method is simple and efficient, as it requires no input besides the force fields required for classical trajectory integration, and is ideal for use in quasiclassical trajectory calculations.
An analytical phase-space model for tidal caustics
NASA Astrophysics Data System (ADS)
Sanderson, Robyn E.; Helmi, Amina
2013-10-01
The class of tidal features around galaxies known as `shells' or `umbrellas' comprises debris that has arisen from high-mass-ratio mergers with low-impact parameter; the nearly radial orbits of the debris give rise to a unique morphology, a universal density profile and a tight correlation between positions and velocities of the material. As such they are accessible to analytical treatment, and can provide a relatively clean system for probing the gravitational potential of the host galaxy. In this work, we present a simple analytical model that describes the density profile, phase-space distribution, and geometry of a shell and whose parameters are directly related to physical characteristics of the interacting galaxies. The model makes three assumptions: the orbit of the interacting galaxies is radial, the potential of the host galaxy at the shell radius is spherical and the satellite galaxy's initial velocity distribution is Maxwellian. We quantify the error introduced by the first two assumptions and show that selecting shells by their appearance on the sky is a sufficient basis to assume that these simplifications are valid. We further demonstrate that (1) given only an image of a shell, the radial gravitational force at the shell edge and the phase-space density of the satellite are jointly constrained, (2) combining the image with measurements of either point line-of-sight velocities or integrated-light spectra will yield an independent estimate of the gravitational force at a shell and (3) an independent measurement of this force is obtained for each shell observed around a given galaxy, potentially enabling a determination of the galactic mass distribution.
Wigner phase space distribution via classical adiabatic switching
NASA Astrophysics Data System (ADS)
Bose, Amartya; Makri, Nancy
2015-09-01
Evaluation of the Wigner phase space density for systems of many degrees of freedom presents an extremely demanding task because of the oscillatory nature of the Fourier-type integral. We propose a simple and efficient, approximate procedure for generating the Wigner distribution that avoids the computational difficulties associated with the Wigner transform. Starting from a suitable zeroth-order Hamiltonian, for which the Wigner density is available (either analytically or numerically), the phase space distribution is propagated in time via classical trajectories, while the perturbation is gradually switched on. According to the classical adiabatic theorem, each trajectory maintains a constant action if the perturbation is switched on infinitely slowly. We show that the adiabatic switching procedure produces the exact Wigner density for harmonic oscillator eigenstates and also for eigenstates of anharmonic Hamiltonians within the Wentzel-Kramers-Brillouin (WKB) approximation. We generalize the approach to finite temperature by introducing a density rescaling factor that depends on the energy of each trajectory. Time-dependent properties are obtained simply by continuing the integration of each trajectory under the full target Hamiltonian. Further, by construction, the generated approximate Wigner distribution is invariant under classical propagation, and thus, thermodynamic properties are strictly preserved. Numerical tests on one-dimensional and dissipative systems indicate that the method produces results in very good agreement with those obtained by full quantum mechanical methods over a wide temperature range. The method is simple and efficient, as it requires no input besides the force fields required for classical trajectory integration, and is ideal for use in quasiclassical trajectory calculations.
Dynamics of Structures in Configuration Space and Phase Space: An Introductory Tutorial
NASA Astrophysics Data System (ADS)
Diamond, P. H.; Kosuga, Y.; Lesur, M.
2015-12-01
Some basic ideas relevant to the dynamics of phase space and real space structures are presented in a pedagogical fashion. We focus on three paradigmatic examples, namely; G. I. Taylor's structure based re-formulation of Rayleigh's stability criterion and its implications for zonal flow momentum balance relations; Dupree's mechanism for nonlinear current driven ion acoustic instability and its implication for anomalous resistivity; and the dynamics of structures in drift and gyrokinetic turbulence and their relation to zonal flow physics. We briefly survey the extension of mean field theory to calculate evolution in the presence of localized structures for regimes where Kubo number K ≃ 1 rather than K ≪ 1, as is usual for quasilinear theory.
A varying polytropic gas universe and phase space analysis
NASA Astrophysics Data System (ADS)
Khurshudyan, M.
2016-05-01
In this paper, we will consider a phenomenological model of a dark fluid that is able to explain an accelerated expansion of our low redshift universe and the phase transition to this accelerated expanding universe. Recent developments in modern cosmology towards understanding of the accelerated expansion of the large scale universe involve various scenarios and approaches. Among these approaches, one of well-known and accepted practice is modeling of the content of our universe via dark fluid. There are various models of dark energy fluid actively studied in recent literature and polytropic gas is among them. In this work, we will consider a varying polytropic gas which is a phenomenological modification of polytropic gas. Our model of varying polytropic dark fluid has been constructed to analogue to a varying Chaplygin gas actively discussed in the literature. We will consider interacting models, where dark matter is a pressureless fluid, to have a comprehensive picture. Phase space analysis is an elegant mathematical tool to earn general understanding of large scale universe and easily see an existence of a solution to cosmological coincidence problem. Imposing some constraints on parameters of the models, we found late time attractors for each case analytically. Cosmological consequences for the obtained late time attractors are discussed.
Quantum trajectories in complex phase space: multidimensional barrier transmission.
Wyatt, Robert E; Rowland, Brad A
2007-07-28
The quantum Hamilton-Jacobi equation for the action function is approximately solved by propagating individual Lagrangian quantum trajectories in complex-valued phase space. Equations of motion for these trajectories are derived through use of the derivative propagation method (DPM), which leads to a hierarchy of coupled differential equations for the action function and its spatial derivatives along each trajectory. In this study, complex-valued classical trajectories (second order DPM), along which is transported quantum phase information, are used to study low energy barrier transmission for a model two-dimensional system involving either an Eckart or Gaussian barrier along the reaction coordinate coupled to a harmonic oscillator. The arrival time for trajectories to reach the transmitted (product) region is studied. Trajectories launched from an "equal arrival time surface," defined as an isochrone, all reach the real-valued subspace in the transmitted region at the same time. The Rutherford-type diffraction of trajectories around poles in the complex extended Eckart potential energy surface is described. For thin barriers, these poles are close to the real axis and present problems for computing the transmitted density. In contrast, for the Gaussian barrier or the thick Eckart barrier where the poles are further from the real axis, smooth transmitted densities are obtained. Results obtained using higher-order quantum trajectories (third order DPM) are described for both thick and thin barriers, and some issues that arise for thin barriers are examined. PMID:17672677
Sanpei, Akio; Soga, Yukihiro; Ito, Kiyokazu; Himura, Haruhiko
2015-06-29
A trilinear phase space analysis is applied for dynamics of three electron clumps confined with a Penning-Malmberg trap. We show that the Aref’s concept of phase space describe the observed features of the dynamics of three point vortices qualitatively. In vacuum, phase point P moves to physical region boundary in phase space, i.e. triangular configuration cannot be kept. With the addition of a low level background vorticity distribution (BGVD), the excursion of the clumps is reduced and the distance between P and stable point does not extend in the phase space.
Nonlinear Phase Mixing and Phase-Space Cascade of Entropy in Gyrokinetic Plasma Turbulence
Tatsuno, T.; Dorland, W.; Plunk, G. G.; Schekochihin, A. A.; Barnes, M.
2009-07-03
Electrostatic turbulence in weakly collisional, magnetized plasma can be interpreted as a cascade of entropy in phase space, which is proposed as a universal mechanism for dissipation of energy in magnetized plasma turbulence. When the nonlinear decorrelation time at the scale of the thermal Larmor radius is shorter than the collision time, a broad spectrum of fluctuations at sub-Larmor scales is numerically found in velocity and position space, with theoretically predicted scalings. The results are important because they identify what is probably a universal Kolmogorov-like regime for kinetic turbulence; and because any physical process that produces fluctuations of the gyrophase-independent part of the distribution function may, via the entropy cascade, result in turbulent heating at a rate that increases with the fluctuation amplitude, but is independent of the collision frequency.
Quantum dynamics in phase space: Moyal trajectories 2
Braunss, G.
2013-01-15
Continuing a previous paper [G. Braunss, J. Phys. A: Math. Theor. 43, 025302 (2010)] where we had calculated Planck-Constant-Over-Two-Pi {sup 2}-approximations of quantum phase space viz. Moyal trajectories of examples with one and two degrees of freedom, we present in this paper the calculation of Planck-Constant-Over-Two-Pi {sup 2}-approximations for four examples: a two-dimensional Toda chain, the radially symmetric Schwarzschild field, and two examples with three degrees of freedom, the latter being the nonrelativistic spherically Coulomb potential and the relativistic cylinder symmetrical Coulomb potential with a magnetic field H. We show in particular that an Planck-Constant-Over-Two-Pi {sup 2}-approximation of the nonrelativistic Coulomb field has no singularity at the origin (r= 0) whereas the classical trajectories are singular at r= 0. In the third example, we show in particular that for an arbitrary function {gamma}(H, z) the expression {beta}{identical_to}p{sub z}+{gamma}(H, z) is classically ( Planck-Constant-Over-Two-Pi = 0) a constant of motion, whereas for Planck-Constant-Over-Two-Pi {ne} 0 this holds only if {gamma}(H, z) is an arbitrary polynomial of second order in z. This statement is shown to extend correspondingly to a cylinder symmetrical Schwarzschild field with a magnetic field. We exhibit in detail a number of properties of the radially symmetric Schwarzschild field. We exhibit finally the problems of the nonintegrable Henon-Heiles Hamiltonian and give a short review of the regular Hilbert space representation of Moyal operators.
Phase space optics: an engineering tool for illumination design
NASA Astrophysics Data System (ADS)
Herkommer, Alois M.; Rausch, Denise
2012-06-01
For imaging design aberration theory provides solid ground for the layout and development of optical systems. Together with general design rules it will guide the optical engineer towards a valid starting point for his system. Illumination design is quite different: Often first system layouts are based on experience, rather than on a systematic approach. In addition radiometric nomenclature and definitions can be quite confusing, due to the variety of radiant performance definitions. Also at a later stage in the design, the performance evaluation usually requires extensive statistical raytracing, in order to confirm the specified energetic quantities. In general it would therefore be helpful for illumination designers, especially beginners, to have an engineering tool, which allows a fast, systematic and illustrative access to illumination design problems. We show that phase space methods can provide such a tool and moreover allow a consistent approach to radiometry. Simple illustrative methods can be used to layout and understand even complex illumination components like integrator rods and optical arrays.
Phase Space Dissimilarity Measures for Structural Health Monitoring
Bubacz, Jacob A; Chmielewski, Hana T; Pape, Alexander E; Depersio, Andrew J; Hively, Lee M; Abercrombie, Robert K; Boone, Shane
2011-11-01
A novel method for structural health monitoring (SHM), known as the Phase Space Dissimilarity Measures (PSDM) approach, is proposed and developed. The patented PSDM approach has already been developed and demonstrated for a variety of equipment and biomedical applications. Here, we investigate SHM of bridges via analysis of time serial accelerometer measurements. This work has four aspects. The first is algorithm scalability, which was found to scale linearly from one processing core to four cores. Second, the same data are analyzed to determine how the use of the PSDM approach affects sensor placement. We found that a relatively low-density placement sufficiently captures the dynamics of the structure. Third, the same data are analyzed by unique combinations of accelerometer axes (vertical, longitudinal, and lateral with respect to the bridge) to determine how the choice of axes affects the analysis. The vertical axis is found to provide satisfactory SHM data. Fourth, statistical methods were investigated to validate the PSDM approach for this application, yielding statistically significant results.
Phase-space estimate of satellite coverage time
Canavan, G.H.
1992-05-01
This note derives a phase-space estimate of the overlap in satellite coverage and evaluates its impact on the time for a constellation to cover some specified area. The satellites` motion is treated as random in the calculation of the overlaps. Enough passes are prescribed to assure that an adequate probability of observing each area is accumulated. For 0.9--0.99 probabilities of coverage, overlaps increase the time for coverage by factors of 2--4 over no-overlap estimates. This model also gives the probability of different vintages of data. If a given constellation covers the whole Earth in the no-overlap time T{sub 0}, the average vintage of the data over the earth will then be the average
Phase-space estimate of satellite coverage time
Canavan, G.H.
1992-05-01
This note derives a phase-space estimate of the overlap in satellite coverage and evaluates its impact on the time for a constellation to cover some specified area. The satellites' motion is treated as random in the calculation of the overlaps. Enough passes are prescribed to assure that an adequate probability of observing each area is accumulated. For 0.9--0.99 probabilities of coverage, overlaps increase the time for coverage by factors of 2--4 over no-overlap estimates. This model also gives the probability of different vintages of data. If a given constellation covers the whole Earth in the no-overlap time T{sub 0}, the average vintage of the data over the earth will then be the average
Phase-space dissimilarity measures for industrial and biomedical applications
NASA Astrophysics Data System (ADS)
Protopopescu, V. A.; Hively, L. M.
2005-12-01
One of the most important problems in time-series analysis is the suitable characterization of the dynamics for timely, accurate, and robust condition assessment of the underlying system. Machine and physiological processes display complex, non-stationary behaviors that are affected by noise and may range from (quasi-)periodic to completely irregular (chaotic) regimes. Nevertheless, extensive experimental evidence indicates that even when the systems behave very irregularly (e.g., severe tool chatter or cardiac fibrillation), one may assume that - for all practical purposes - the dynamics are confined to low dimensional manifolds. As a result, the behavior of these systems can be described via traditional nonlinear measures (TNM), such as Lyapunov exponents, Kolmogorov entropy, and correlation dimension. While these measures are adequate for discriminating between clear-cut regular and chaotic dynamics, they are not sufficiently sensitive to distinguish between slightly different irregular (chaotic) regimes, especially when data are noisy and/or limited. Both machine and physiological dynamics usually fall into this latter category, creating a massive stumbling block to prognostication of abnormal regimes. We present here a recently developed approach that captures more efficiently changes in the underlying dynamics. We start with process-indicative, time-serial data that are checked for quality and discarded if inadequate. Acceptable data are filtered to remove confounding artifacts (e.g., sinusoidal variation in three-phase electrical signals or eye-blinks and muscular activity in EEG). The artifact-filtered data are then used to recover the essential features of the underlying dynamics via standard time-delay, phase-space reconstruction. One of the main results of this reconstruction is a discrete approximation of the distribution function (DF) on the attractor. Unaltered dynamics yield an unchanging geometry of the attractor and the visitation frequencies of
Computational methods for microfluidic microscopy and phase-space imaging
NASA Astrophysics Data System (ADS)
Pegard, Nicolas Christian Richard
Modern optical devices are made by assembling separate components such as lenses, objectives, and cameras. Traditionally, each part is optimized separately, even though the trade-offs typically limit the performance of the system overall. This component-based approach is particularly unfit to solve the new challenges brought by modern biology: 3D imaging, in vivo environments, and high sample throughput. In the first part of this thesis, we introduce a general method to design integrated optical systems. The laws of wave propagation, the performance of available technology, as well as other design parameters are combined as constraints into a single optimization problem. The solution provides qualitative design rules to improve optical systems as well as quantitative task-specific methods to minimize loss of information. Our results have applications in optical data storage, holography, and microscopy. The second part of this dissertation presents a direct application. We propose a more efficient design for wide-field microscopy with coherent light, based on double transmission through the sample. Historically, speckle noise and aberrations caused by undesired interferences have made coherent illumination unpopular for imaging. We were able to dramatically reduce speckle noise and unwanted interferences using optimized holographic wavefront reconstruction. The resulting microscope not only yields clear coherent images with low aberration---even in thick samples---but also increases contrast and enables optical filtering and in-depth sectioning. In the third part, we develop new imaging techniques that better respond to the needs of modern biology research through implementing optical design optimization. Using a 4D phase-space distribution, we first represent the state and propagation of incoherent light. We then introduce an additional degree of freedom by putting samples in motion in a microfluidic channel, increasing image diversity. From there, we develop a
An Effective Method to Accurately Calculate the Phase Space Factors for β - β - Decay
Neacsu, Andrei; Horoi, Mihai
2016-01-01
Accurate calculations of the electron phase space factors are necessary for reliable predictions of double-beta decay rates and for the analysis of the associated electron angular and energy distributions. We present an effective method to calculate these phase space factors that takes into account the distorted Coulomb field of the daughter nucleus, yet it allows one to easily calculate the phase space factors with good accuracy relative to the most exact methods available in the recent literature.
On the Group of Translations and Inversions of Phase Space and the Wigner Functions
NASA Astrophysics Data System (ADS)
Dahl, Jens Peder
1982-04-01
Grossmann and Royer have recently shown that the Wigner functions are closely related to the set of all translations and inversions of phase space. This allows the phase space representation of quantum mechanics to be constructed directly on the group of phase space translations and inversions. Starting from this observation, we have derived analytical expressions for the matrix elements of the translation and inversion operators, in the harmonic oscillator representation, without introducing coordinate or momentum wavefunctions.
Phase-locked laser array having a non-uniform spacing between lasing regions
NASA Technical Reports Server (NTRS)
Ackley, Donald E. (Inventor)
1986-01-01
A phase-locked semiconductor array wherein the lasing regions of the array are spaced an effective distance apart such that the modes of oscillation of the different lasing regions are phase-locked to one another. The center-to-center spacing between the lasing regions is non-uniform. This variation in spacing perturbs the preferred 180.degree. phase difference between adjacent lasing regions thereby providing an increased yield of arrays exhibiting a single-lobed, far-field radiation pattern.
On coherent-state representations of quantum mechanics: Wave mechanics in phase space
NASA Astrophysics Data System (ADS)
Møller, Klaus B.; Jørgensen, Thomas G.; Torres-Vega, Gabino
1997-05-01
In this article we argue that the state-vector phase-space representation recently proposed by Torres-Vega and co-workers [introduced in J. Chem. Phys. 98, 3103 (1993)] coincides with the totality of coherent-state representations for the Heisenberg-Weyl group. This fact leads to ambiguities when one wants to solve the stationary Schrödinger equation in phase space and we devise two schemes for the removal of these ambiguities. The physical interpretation of the phase-space wave functions is discussed and a procedure for computing expectation values as integrals over phase space is presented. Our formal points are illustrated by two examples.
NASA Technical Reports Server (NTRS)
1984-01-01
The large space structures technology development missions to be performed on an early manned space station was studied and defined and the resources needed and the design implications to an early space station to carry out these large space structures technology development missions were determined. Emphasis is being placed on more detail in mission designs and space station resource requirements.
Generalised partition functions: inferences on phase space distributions
NASA Astrophysics Data System (ADS)
Treumann, Rudolf A.; Baumjohann, Wolfgang
2016-06-01
It is demonstrated that the statistical mechanical partition function can be used to construct various different forms of phase space distributions. This indicates that its structure is not restricted to the Gibbs-Boltzmann factor prescription which is based on counting statistics. With the widely used replacement of the Boltzmann factor by a generalised Lorentzian (also known as the q-deformed exponential function, where κ = 1/|q - 1|, with κ, q ∈ R) both the kappa-Bose and kappa-Fermi partition functions are obtained in quite a straightforward way, from which the conventional Bose and Fermi distributions follow for κ → ∞. For κ ≠ ∞ these are subject to the restrictions that they can be used only at temperatures far from zero. They thus, as shown earlier, have little value for quantum physics. This is reasonable, because physical κ systems imply strong correlations which are absent at zero temperature where apart from stochastics all dynamical interactions are frozen. In the classical large temperature limit one obtains physically reasonable κ distributions which depend on energy respectively momentum as well as on chemical potential. Looking for other functional dependencies, we examine Bessel functions whether they can be used for obtaining valid distributions. Again and for the same reason, no Fermi and Bose distributions exist in the low temperature limit. However, a classical Bessel-Boltzmann distribution can be constructed which is a Bessel-modified Lorentzian distribution. Whether it makes any physical sense remains an open question. This is not investigated here. The choice of Bessel functions is motivated solely by their convergence properties and not by reference to any physical demands. This result suggests that the Gibbs-Boltzmann partition function is fundamental not only to Gibbs-Boltzmann but also to a large class of generalised Lorentzian distributions as well as to the corresponding nonextensive statistical mechanics.
Selected tether applications in space: Phase 2. Executive summary
NASA Technical Reports Server (NTRS)
Thorson, M. H.; Lippy, L. J.
1985-01-01
The application of tether technology has the potential to increase the overall performance efficiency and capability of the integrated space operations and transportation systems through the decade of the 90s. The primary concepts for which significant economic benefits were identified are dependent on the space station as a storage device for angular momentum and as an operating base for the tether system. Concepts examined include: (1) tether deorbit of shuttle from space station; (2) tethered orbit insertion of a spacecraft from shuttle; (3) tethered platform deployed from space station; (4) tether-effected rendezvous of an OMV with a returning OTV; (5) electrodynamic tether as an auxiliary power source for space station; and (6) tether assisted launch of an OTV mission from space station.
Weyl Calculus in Phase Space and the Torres-Vega and Frederick Equation
Gosson, Maurice de
2006-01-04
We show that the Schroedinger equation in phase space proposed by Torres-Vega and Frederick is canonical in the sense that it is a natural consequence of Weyl calculus provided that one lets Heisenberg-Weyl operators act on functions (or half-densities) defined on phase space. We interpret our results in terms of deformation quantization.
Deformed phase space Kaluza-Klein cosmology and late time acceleration
NASA Astrophysics Data System (ADS)
Sabido, M.; Yee-Romero, C.
2016-06-01
The effects of phase space deformations on Kaluza-Klein cosmology are studied. The deformation is introduced by modifying the symplectic structure of the minisuperspace variables. In the deformed model, we find an accelerating scale factor and therefore infer the existence of an effective cosmological constant from the phase space deformation parameter β.
NASA Astrophysics Data System (ADS)
Heiblum, Reuven H.; Altaratz, Orit; Koren, Ilan; Feingold, Graham; Kostinski, Alexander B.; Khain, Alexander P.; Ovchinnikov, Mikhail; Fredj, Erick; Dagan, Guy; Pinto, Lital; Yaish, Ricki; Chen, Qian
2016-06-01
We study the evolution of warm convective cloud fields using large eddy simulations of continental and trade cumulus. Individual clouds are tracked a posteriori from formation to dissipation using a 3-D cloud-tracking algorithm, and results are presented in the phase space of center of gravity altitude versus cloud liquid water mass (CvM space). The CvM space is shown to contain rich information on cloud field characteristics, cloud morphology, and common cloud development pathways, together facilitating a comprehensive understanding of the cloud field. In this part we show how the meteorological (thermodynamic) conditions that determine the cloud properties are projected on the CvM phase space and how changes in the initial conditions affect the clouds' trajectories in this space. This part sets the stage for a detailed microphysical analysis that will be shown in part II.
RF Integration into Helical Magnet for Muon 6-Dimensional Beam Cooling
Yonehara, K.; Kashikhin, V.; Lamm, M.; Lee, A.; Lopes, M.; Zlobin, A.; Johnson, R.P.; Kahn, S.; Neubauer, M.; /Muons Inc., Batavia
2009-05-01
The helical cooling channel is proposed to make a quick muon beam phase space cooling in a short channel length. The challenging part of the helical cooling channel magnet design is how to integrate the RF cavity into the compact helical cooling magnet. This report shows the possibility of the integration of the system.
Common features in phase-space networks of frustrated spin models and lattice-gas models
NASA Astrophysics Data System (ADS)
Wang, Feng; Peng, Yi; Han, Yilong
2012-02-01
We mapped the phase spaces of the following four models into networks: (1a) the Ising antiferromagnet on triangular lattice at the ground state and (1b) above the ground state, (2) the six-vertex model (i.e. square ice or spin ice), (3) 1D lattice gas and (4) 2D lattice gas. Their phase-space networks share some common features including the Gaussian degree distribution, the Gaussian spectral density, and the small-world properties. Models 1a, 2 and 3 with long-range correlations in real space exhibit fractal phase spaces, while models 1b and 4 with short-range correlations in real space exhibit non-fractal phase spaces. This result supports one of the untested assumptions in Tsallis's non-extensive statistics.
Cosmic evolution from phase transition of three-dimensional flat space.
Bagchi, Arjun; Detournay, Stephane; Grumiller, Daniel; Simón, Joan
2013-11-01
Flat space cosmology spacetimes are exact time-dependent solutions of three-dimensional gravity theories, such as Einstein gravity or topologically massive gravity. We exhibit a novel kind of phase transition between these cosmological spacetimes and the Minkowski vacuum. At sufficiently high temperature, (rotating) hot flat space tunnels into a universe described by flat space cosmology. PMID:24237503
Trajectories and causal phase-space approach to relativistic quantum mechanics
Holland, P.R.; Kyprianidis, A.; Vigier, J.P.
1987-05-01
The authors analyze phase-space approaches to relativistic quantum mechanics from the viewpoint of the causal interpretation. In particular, they discuss the canonical phase space associated with stochastic quantization, its relation to Hilbert space, and the Wigner-Moyal formalism. They then consider the nature of Feynman paths, and the problem of nonlocality, and conclude that a perfectly consistent relativistically covariant interpretation of quantum mechanics which retains the notion of particle trajectory is possible.
Integrated study plan for space bioprocessing (phase 1)
NASA Technical Reports Server (NTRS)
1977-01-01
Current economic evaluation and analytical techniques are applied to decision problems faced by the space bioprocessing program. NASA decision makers are enabled to choose candidate substances, after ranking them according to their potential economic benefit. The determination of appropriate evaluation techniques necessary to obtain measures of potential economic benefits which result from the pursuit of various space bioprocessing endeavors are focused upon. The treatment of each disease is impacted by a successful outcome of space bioprocessing and specify data and other input needs for each candidate substance.
Space Station Freedom - Approaching the critical design phase
NASA Technical Reports Server (NTRS)
Kohrs, Richard H.; Huckins, Earle, III
1992-01-01
The status and future developments of the Space Station Freedom are discussed. To date detailed design drawings are being produced to manufacture SSF hardware. A critical design review (CDR) for the man-tended capability configuration is planned to be performed in 1993 under the SSF program. The main objective of the CDR is to enable the program to make a full commitment to proceed to manufacture parts and assemblies. NASA recently signed a contract with the Russian space company, NPO Energia, to evaluate potential applications of various Russian space hardware for on-going NASA programs.
Geometric phase in a flat space for electromagnetic scalar waves.
Luis, Alfredo
2006-08-15
We show the existence of a fundamental geometric phase for classical electromagnetic fields arising after cyclic paths in a plane instead of a sphere. This phase is dispersive, is not related to polarization, distinguishes geometrical from wave optics, and can be easily measured in an interferometric arrangement. PMID:16880859
Research opportunities in space motion sickness, phase 2
NASA Technical Reports Server (NTRS)
Talbot, J. M.
1983-01-01
Space and motion sickness, the current and projected NASA research program, and the conclusions and suggestions of the ad hoc Working Group are summarized. The frame of reference for the report is ground-based research.
Space station gas compressor technology study program, phase 1
NASA Technical Reports Server (NTRS)
Hafele, B. W.; Rapozo, R. R.
1989-01-01
The objectives were to identify the space station waste gases and their characteristics, and to investigate compressor and dryer types, as well as transport and storage requirements with tradeoffs leading to a preliminary system definition.
Space shuttle auxiliary power unit study, phase 2
NASA Technical Reports Server (NTRS)
Binsley, R. L.; Krause, A. A.; Maddox, R. D.; Marcy, R. D.; Siegler, R. S.
1972-01-01
A study was performed to establish the preliminary design of the space shuttle auxiliary power unit. Details of the analysis, optimizations, and design of the components, subsystems and systems are presented.
Multimegawatt space nuclear power supply: Phase 1, Final report
Not Available
1989-02-17
The preliminary safety assessment report analyzes the potential radiological risk of the integrated MSNPS with the launch vehicle including interface with the weapon system. Most emphasis will be placed the prime power concept design. Safety problems can occur any time during the entire life cycle of the system including contingency phases. The preliminary safety assessment report is to be delivered at the end of phase 2. This assessment will be the basis of the safety requirements which will be applied to the design of the MSNPS as it develops in subsequent phases. The assessment also focuses design activities on specific high-risk scenarios and missions that may impact safety.
Multimegawatt space nuclear power supply: Phase 1, Final report
Not Available
1989-02-17
The Phase 2 program objectives are to (1) demonstrate concept feasibility, (2) develop a preliminary design, and (3) complete Phase 3 engineering development and ground test plans. The approach to accomplish these objectives is to prove technical feasibility of our baseline design early in the program while maintaining flexibility to easily respond to changing requirements and advances in technology. This approach recognizes that technology is advancing rapidly while the operational phase MSNPS is 15 to 20 years in the future. This plan further recognizes that the weapons platform and Advanced Launch System (ALS) are in very early program definition stages; consequently, their requirements, interfaces, and technological basis will evolve. This document outlines the Phase 2 plan along with task scheduling of the various program aspects.
Space station contamination control study: Internal combustion, phase 1
NASA Technical Reports Server (NTRS)
Ruggeri, Robert T.
1987-01-01
Contamination inside Space Station modules was studied to determine the best methods of controlling contamination. The work was conducted in five tasks that identified existing contamination control requirements, analyzed contamination levels, developed outgassing specification for materials, wrote a contamination control plan, and evaluated current materials of offgassing tests used by NASA. It is concluded that current contamination control methods can be made to function on the Space Station for up to 1000 days, but that current methods are deficient for periods longer than about 1000 days.
Discrete phase-space structure of n-qubit mutually unbiased bases
Klimov, A.B.; Romero, J.L.; Bjoerk, G.; Sanchez-Soto, L.L.
2009-01-15
We work out the phase-space structure for a system of n qubits. We replace the field of real numbers that label the axes of the continuous phase space by the finite field GF(2{sup n}) and investigate the geometrical structures compatible with the notion of unbiasedness. These consist of bundles of discrete curves intersecting only at the origin and satisfying certain additional properties. We provide a simple classification of such curves and study in detail the four- and eight-dimensional cases, analyzing also the effect of local transformations. In this way, we provide a comprehensive phase-space approach to the construction of mutually unbiased bases for n qubits.
Large space telescope, phase A. Volume 3: Optical telescope assembly
NASA Technical Reports Server (NTRS)
1972-01-01
The development and characteristics of the optical telescope assembly for the Large Space Telescope are discussed. The systems considerations are based on mission-related parameters and optical equipment requirements. Information is included on: (1) structural design and analysis, (2) thermal design, (3) stabilization and control, (4) alignment, focus, and figure control, (5) electronic subsystem, and (6) scientific instrument design.
Space radiation hazards to Project Skylab photographic film, phase 2
NASA Technical Reports Server (NTRS)
Hill, C. W.; Neville, C. F.
1971-01-01
The results of a study of space radiation hazards to Project Skylab photographic film are presented. Radiation components include trapped protons, trapped electrons, bremsstrahlung, and galactic cosmic radiation. The shielding afforded by the Skylab cluster is taken into account with a 5000 volume element mathematical model. A preliminary survey of expected proton spectrometer data is reported.
Large space telescope, phase A. Volume 4: Scientific instrument package
NASA Technical Reports Server (NTRS)
1972-01-01
The design and characteristics of the scientific instrument package for the Large Space Telescope are discussed. The subjects include: (1) general scientific objectives, (2) package system analysis, (3) scientific instrumentation, (4) imaging photoelectric sensors, (5) environmental considerations, and (6) reliability and maintainability.
Large space telescope, phase A. Volume 5: Support systems module
NASA Technical Reports Server (NTRS)
1972-01-01
The development and characteristics of the support systems module for the Large Space Telescope are discussed. The following systems and described: (1) thermal control, (2) electrical, (3) communication and data landing, (4) attitude control system, and (5) structural features. Analyses of maintainability and reliability considerations are included.
Phase-space representation of a non-Hermitian system with PT symmetry
NASA Astrophysics Data System (ADS)
Praxmeyer, Ludmila; Yang, Popo; Lee, Ray-Kuang
2016-04-01
We present a phase-space study of a non-Hermitian Hamiltonian with PT symmetry based on the Wigner distribution function. For an arbitrary complex potential, we derive a generalized continuity equation for the Wigner function flow and calculate the related circulation values. Studying the vicinity of an exceptional point, we show that a PT -symmetric phase transition from an unbroken PT -symmetry phase to a broken one is a second-order phase transition.
Deep Space Habitat Concept of Operations for Transit Mission Phases
NASA Technical Reports Server (NTRS)
Hoffman, Stephen J.
2011-01-01
The National Aeronautics and Space Administration (NASA) has begun evaluating various mission and system components of possible implementations of what the U.S. Human Spaceflight Plans Committee (also known as the Augustine Committee) has named the flexible path (Anon., 2009). As human spaceflight missions expand further into deep space, the duration of these missions increases to the point where a dedicated crew habitat element appears necessary. There are several destinations included in this flexible path a near Earth asteroid (NEA) mission, a Phobos/Deimos (Ph/D) mission, and a Mars surface exploration mission that all include at least a portion of the total mission in which the crew spends significant periods of time (measured in months) in the deep space environment and are thus candidates for a dedicated habitat element. As one facet of a number of studies being conducted by the Human Spaceflight Architecture Team (HAT) a workshop was conducted to consider how best to define and quantify habitable volume for these future deep space missions. One conclusion reached during this workshop was the need for a description of the scope and scale of these missions and the intended uses of a habitat element. A group was set up to prepare a concept of operations document to address this need. This document describes a concept of operations for a habitat element used for these deep space missions. Although it may eventually be determined that there is significant overlap with this concept of operations and that of a habitat destined for use on planetary surfaces, such as the Moon and Mars, no such presumption is made in this document.
Equilibrium Phase Behavior of a Continuous-Space Microphase Former
NASA Astrophysics Data System (ADS)
Zhuang, Yuan; Zhang, Kai; Charbonneau, Patrick
2016-03-01
Periodic microphases universally emerge in systems for which short-range interparticle attraction is frustrated by long-range repulsion. The morphological richness of these phases makes them desirable material targets, but our relatively coarse understanding of even simple models hinders controlling their assembly. We report here the solution of the equilibrium phase behavior of a microscopic microphase former through specialized Monte Carlo simulations. The results for cluster crystal, cylindrical, double gyroid, and lamellar ordering qualitatively agree with a Landau-type free energy description and reveal the nontrivial interplay between cluster, gel, and microphase formation.
Transverse emittance and phase space program developed for use at the Fermilab A0 Photoinjector
Thurman-Keup, R.; Johnson, A.S.; Lumpkin, A.H.; Ruan, J.; /Fermilab
2011-03-01
The Fermilab A0 Photoinjector is a 16 MeV high intensity, high brightness electron linac developed for advanced accelerator R&D. One of the key parameters for the electron beam is the transverse beam emittance. Here we report on a newly developed MATLAB based GUI program used for transverse emittance measurements using the multi-slit technique. This program combines the image acquisition and post-processing tools for determining the transverse phase space parameters with uncertainties. An integral part of accelerator research is a measurement of the beam phase space. Measurements of the transverse phase space can be accomplished by a variety of methods including multiple screens separated by drift spaces, or by sampling phase space via pepper pots or slits. In any case, the measurement of the phase space parameters, in particular the emittance, can be drastically simplified and sped up by automating the measurement in an intuitive fashion utilizing a graphical interface. At the A0 Photoinjector (A0PI), the control system is DOOCS, which originated at DESY. In addition, there is a library for interfacing to MATLAB, a graphically capable numerical analysis package sold by The Mathworks. It is this graphical package which was chosen as the basis for a graphical phase space measurement system due to its combination of analysis and display capabilities.
NASA Astrophysics Data System (ADS)
Hajian, K.; Sheikh-Jabbari, M. M.
2016-02-01
We provide a general formulation for calculating conserved charges for solutions to generally covariant gravitational theories with possibly other internal gauge symmetries, in any dimensions and with generic asymptotic behaviors. These solutions are generically specified by a number of exact (continuous, global) symmetries and some parameters. We define "parametric variations" as field perturbations generated by variations of the solution parameters. Employing the covariant phase space method, we establish that the set of these solutions (up to pure gauge transformations) form a phase space, the solution phase space, and that the tangent space of this phase space includes the parametric variations. We then compute conserved charge variations associated with the exact symmetries of the family of solutions, caused by parametric variations. Integrating the charge variations over a path in the solution phase space, we define the conserved charges. In particular, we revisit "black hole entropy as a conserved charge" and the derivation of the first law of black hole thermodynamics. We show that the solution phase space setting enables us to define black hole entropy by an integration over any compact, codminesion-2, smooth spacelike surface encircling the hole, as well as to a natural generalization of Wald and Iyer-Wald analysis to cases involving gauge fields.
The stress-energy tensor and the deflection of light in 6-dimensional general relativity
NASA Astrophysics Data System (ADS)
Cocke, W. J.
1996-03-01
We find the stress-energy tensor of a perfect fluid in the 6-dimensional spacetime proposed by Cole. Using the weak-field Newtonian approximation of general relativity gives a constant of proportionality in Einstein's field equations that differs by a factor of 4/6 from the usual one and shows that Cole's extension of the Schwarzschild metric to 6 dimensions is not valid for a gravitating mass of “ordinary” matter. A subsequent evaluation of the deflection of starlight for the 6-d spacetime gives a result that is 4/6 of the 4-d result. We conclude that if spacetime is 6-dimensional, one must find a different way to deal with gravity.
Inflationary perturbation theory is geometrical optics in phase space
NASA Astrophysics Data System (ADS)
Seery, David; Mulryne, David J.; Frazer, Jonathan; Ribeiro, Raquel H.
2012-09-01
A pressing problem in comparing inflationary models with observation is the accurate calculation of correlation functions. One approach is to evolve them using ordinary differential equations ("transport equations"), analogous to the Schwinger-Dyson hierarchy of in-out quantum field theory. We extend this approach to the complete set of momentum space correlation functions. A formal solution can be obtained using raytracing techniques adapted from geometrical optics. We reformulate inflationary perturbation theory in this language, and show that raytracing reproduces the familiar "δN" Taylor expansion. Our method produces ordinary differential equations which allow the Taylor coefficients to be computed efficiently. We use raytracing methods to express the gauge transformation between field fluctuations and the curvature perturbation, ζ, in geometrical terms. Using these results we give a compact expression for the nonlinear gauge-transform part of fNL in terms of the principal curvatures of uniform energy-density hypersurfaces in field space.
Scaling and the start-up phase of space industrialization
NASA Technical Reports Server (NTRS)
Criswell, D. R.
1979-01-01
By terrestrial standards very little mass is needed to construct the space portion of a 10,000 megawatt (10 GW) power system. Use of lunar materials makes it reasonable to consider alternatives to silicon solar cells for conversion of sunlight to electricity and thereby avoid present major problems associated with solar cell production. Machinery needed on the moon to excavate lunar materials and deliver them to a transport system, to beneficiate lunar materials, to produce glasses and ceramics from lunar materials and to chemically process lunar materials into their major oxides and elements are minor mass fractions of the total mass of equipment needed in space to produce an SPS. In addition the processing equipment can throughput several hundred times their own mass each year with very little requirement for makeup mass from earth.
Inflationary perturbation theory is geometrical optics in phase space
Seery, David; Frazer, Jonathan; Mulryne, David J.; Ribeiro, Raquel H. E-mail: D.Mulryne@qmul.ac.uk E-mail: R.Ribeiro@damtp.cam.ac.uk
2012-09-01
A pressing problem in comparing inflationary models with observation is the accurate calculation of correlation functions. One approach is to evolve them using ordinary differential equations ({sup t}ransport equations{sup )}, analogous to the Schwinger-Dyson hierarchy of in-out quantum field theory. We extend this approach to the complete set of momentum space correlation functions. A formal solution can be obtained using raytracing techniques adapted from geometrical optics. We reformulate inflationary perturbation theory in this language, and show that raytracing reproduces the familiar 'δN' Taylor expansion. Our method produces ordinary differential equations which allow the Taylor coefficients to be computed efficiently. We use raytracing methods to express the gauge transformation between field fluctuations and the curvature perturbation, ζ, in geometrical terms. Using these results we give a compact expression for the nonlinear gauge-transform part of f{sub NL} in terms of the principal curvatures of uniform energy-density hypersurfaces in field space.
Modular space station phase B extension: Mass properties
NASA Technical Reports Server (NTRS)
Duffey, L. A.
1971-01-01
The MSS system, capable of supporting a six-man crew, is described as consisting of four common station modules, two special modules (core and power), and a cargo module arranged in a cruciform. The station buildup, and space station subsystems including environmental control life support, electrical power, guidance and control are also described. The MSS system weights are presented for design-to-weight, closeout weights, and shuttle payload weights.
Phase-space description of plasma waves. Part 1. Linear theory
NASA Astrophysics Data System (ADS)
Biro, T.; Rönnmark, K.
1992-06-01
We develop an (r, k) phase-space description of waves in plasmas by introducing Gaussian window functions to separate short-scale oscillations from long-scale modulations of the wave fields and variations in the plasma parameters. To obtain a wave equation that unambiguously separates conservative dynamics from dissipation in an inhomogeneous and time-varying background plasma, we first discuss the proper form of the current response function. In analogy with the particle distribution function f(v, r, t), we introduce a wave density N(k, r, t) on phase space. This function is proved to satisfy a simple continuity equation. Dissipation is also included, and this allows us to describe the damping or growth of wave density along rays. Problems involving geometric optics of continuous media often appear simpler when viewed in phase space, since the flow of N in phase space is incompressible.
Emittance and Phase Space Exchange for Advanced Beam Manipulation and Diagnostics
Xiang, Dao; Chao, Alex; /SLAC
2012-04-27
Alternative chicane-type beam lines are proposed for exact emittance exchange between transverse phase space (x,x') and longitudinal phase space (z,{delta}), where x is the transverse position, x' is the transverse divergence, and z and {delta} are relative longitudinal position and energy deviation with respect to the reference particle. Methods to achieve exact phase space exchanges, i.e., mapping x to z, x' to {delta}, z to x, and {delta} to x', are suggested. Schemes to mitigate and completely compensate for the thick-lens effect of the transverse cavity on emittance exchange are studied. Some applications of the phase space exchange for advanced beam manipulation and diagnostics are discussed.
Phase III Simplified Integrated Test (SIT) results - Space Station ECLSS testing
NASA Technical Reports Server (NTRS)
Roberts, Barry C.; Carrasquillo, Robyn L.; Dubiel, Melissa Y.; Ogle, Kathryn Y.; Perry, Jay L.; Whitley, Ken M.
1990-01-01
During 1989, phase III testing of Space Station Freedom Environmental Control and Life Support Systems (ECLSS) began at Marshall Space Flight Center (MSFC) with the Simplified Integrated Test. This test, conducted at the MSFC Core Module Integration Facility (CMIF), was the first time the four baseline air revitalization subsystems were integrated together. This paper details the results and lessons learned from the phase III SIT. Future plans for testing at the MSFC CMIF are also discussed.
Experimental method of optical coherence characterization in phase-space measurement
NASA Astrophysics Data System (ADS)
Li, Jie-En; Fu, Jhih-Syuan; Hsiao, Ming-Shu; Tien, Chung-Hao
2015-09-01
A novel approach of phase-space measurement made its debut with the experimental result. We first designed an experiment based on the Young's interferometer to characterization the optical coherence property of light source. A well-known algorithm called Hough transformation was applied to deal with the misalignment of micro-lens array by post-processing. The phase-space image of plane wave was then reconstructed from the realigned raw image. Finally, the properties of this system were discussed.
Multiple transition states and roaming in ion-molecule reactions: A phase space perspective
NASA Astrophysics Data System (ADS)
Mauguière, Frédéric A. L.; Collins, Peter; Ezra, Gregory S.; Farantos, Stavros C.; Wiggins, Stephen
2014-01-01
We provide a dynamical interpretation of the recently identified ‘roaming' mechanism for molecular dissociation reactions in terms of geometrical structures in phase space. These are NHIMs (Normally Hyperbolic Invariant Manifolds) and their stable/unstable manifolds that define transition states for ion-molecule association or dissociation reactions. The associated dividing surfaces rigorously define a roaming region of phase space, in which both reactive and non reactive trajectories can be trapped for arbitrarily long times.
Subpicosecond electron bunch train production using a phase-space exchange technique
Sun, Y.-E.; Piot, P.; Johnson, A.S.; Lumpkin, A.H.; Maxwell, T.J.; Ruan, J.; Thurman-Keup, R.M.; /Fermilab
2011-03-01
Our recent experimental demonstration of a photoinjector electron bunch train with sub-picosecond structures is reported in this paper. The experiment is accomplished by converting an initially horizontal beam intensity modulation into a longitudinal phase space modulation, via a beamline capable of exchanging phase-space coordinates between the horizontal and longitudinal degrees of freedom. The initial transverse modulation is produced by intercepting the beam with a multislit mask prior to the exchange. We also compare our experimental results with numerical simulations.
Phase-space distributions in quasi-polar coordinates and the fractional Fourier transform.
Alieva, T; Bastiaans, M J
2000-12-01
The ambiguity function and Cohen's class of bilinear phase-space distributions are represented in a quasipolar coordinate system instead of in a Cartesian system. Relationships between these distributions and the fractional Fourier transform are derived; in particular, derivatives of the ambiguity function are related to moments of the fractional power spectra. A simplification is achieved for the description of underspread signals, for optical beam characterization, and for the generation of signal-adaptive phase-space distributions. PMID:11140493
Linear processes in high dimensions: Phase space and critical properties.
Mastromatteo, Iacopo; Bacry, Emmanuel; Muzy, Jean-François
2015-04-01
In this work we investigate the generic properties of a stochastic linear model in the regime of high dimensionality. We consider in particular the vector autoregressive (VAR) model and the multivariate Hawkes process. We analyze both deterministic and random versions of these models, showing the existence of a stable phase and an unstable phase. We find that along the transition region separating the two regimes the correlations of the process decay slowly, and we characterize the conditions under which these slow correlations are expected to become power laws. We check our findings with numerical simulations showing remarkable agreement with our predictions. We finally argue that real systems with a strong degree of self-interaction are naturally characterized by this type of slow relaxation of the correlations. PMID:25974473
Linear processes in high dimensions: Phase space and critical properties
NASA Astrophysics Data System (ADS)
Mastromatteo, Iacopo; Bacry, Emmanuel; Muzy, Jean-François
2015-04-01
In this work we investigate the generic properties of a stochastic linear model in the regime of high dimensionality. We consider in particular the vector autoregressive (VAR) model and the multivariate Hawkes process. We analyze both deterministic and random versions of these models, showing the existence of a stable phase and an unstable phase. We find that along the transition region separating the two regimes the correlations of the process decay slowly, and we characterize the conditions under which these slow correlations are expected to become power laws. We check our findings with numerical simulations showing remarkable agreement with our predictions. We finally argue that real systems with a strong degree of self-interaction are naturally characterized by this type of slow relaxation of the correlations.
Phase 1 Space Fission Propulsion System Design Considerations
NASA Technical Reports Server (NTRS)
Houts, Mike; VanDyke, Melissa; Godfroy, Tom; Pedersen, Kevin; Martin, James; Carter, Robert; Dickens, Ricky; Salvail, Pat; Hrbud, Ivana; Rodgers, Stephen L. (Technical Monitor)
2001-01-01
Fission technology can enable rapid, affordable access to any point in the solar system. If fission propulsion systems are to be developed to their full potential; however, near-term customers must be identified and initial fission systems successfully developed, launched, and operated. Studies conducted in fiscal year 2001 (IISTP, 2001) show that fission electric propulsion (FEP) systems operating at 80 kWe or above could enhance or enable numerous robotic outer solar system missions of interest. At these power levels it is possible to develop safe, affordable systems that meet mission performance requirements. In selecting the system design to pursue, seven evaluation criteria were identified: safety, reliability, testability, specific mass, cost, schedule, and programmatic risk. A top-level comparison of three potential concepts was performed: an SP-100 based pumped liquid lithium system, a direct gas cooled system, and a heatpipe cooled system. For power levels up to at least 500 kWt (enabling electric power levels of 125-175 kWe, given 25-35% power conversion efficiency) the heatpipe system has advantages related to several criteria and is competitive with respect to all. Hardware-based research and development has further increased confidence in the heatpipe approach. Successful development and utilization of a "Phase 1" fission electric propulsion system will enable advanced Phase 2 and Phase 3 systems capable of providing rapid, affordable access to any point in the solar system.
Self-similarity of phase-space networks of frustrated spin models and lattice gas models
NASA Astrophysics Data System (ADS)
Peng, Yi; Wang, Feng; Han, Yilong
2013-03-01
We studied the self-similar properties of the phase-spaces of two frustrated spin models and two lattice gas models. The frustrated spin models included (1) the anti-ferromagnetic Ising model on a two-dimensional triangular lattice (1a) at the ground states and (1b) above the ground states and (2) the six-vertex model. The two lattice gas models were (3) the one-dimensional lattice gas model and (4) the two-dimensional lattice gas model. The phase spaces were mapped to networks so that the fractal analysis of complex networks could be applied, i.e. the box-covering method and the cluster-growth method. These phase spaces, in turn, establish new classes of networks with unique self-similar properties. Models 1a, 2, and 3 with long-range power-law correlations in real space exhibit fractal phase spaces, while models 1b and 4 with short-range exponential correlations in real space exhibit nonfractal phase spaces. This behavior agrees with one of untested assumptions in Tsallis nonextensive statistics. Hong Kong GRC grants 601208 and 601911
Singularity problem and phase-space noncanonical noncommutativity
NASA Astrophysics Data System (ADS)
Bastos, Catarina; Bertolami, Orfeu; Dias, Nuno Costa; Prata, João Nuno
2010-08-01
The Wheeler-DeWitt equation arising from a Kantowski-Sachs model is considered for a Schwarzschild black hole under the assumption that the scale factors and the associated momenta satisfy a noncanonical noncommutative extension of the Heisenberg-Weyl algebra. An integral of motion is used to factorize the wave function into an oscillatory part and a function of a configuration space variable. The latter is shown to be normalizable using asymptotic arguments. It is then shown that on the hypersurfaces of constant value of the argument of the wave function’s oscillatory piece, the probability vanishes in the vicinity of the black hole singularity.
Space shuttle phase B. Volume 1: Executive summary
NASA Technical Reports Server (NTRS)
1972-01-01
A study was conducted to identify the differences among total system concepts of space shuttle configurations. Emphasis was placed on concepts that lead to selection of a system that performs the missions within budget and schedule constraints. The spectrum of launch vehicle configurations is illustrated. An inboard profile of the spacecraft is presented to show the interior arrangement of the major subsystems. The performance prediction of the spacecraft during specified portions of the mission is analyzed. A cost comparison of the various concepts is included.
Space qualified Nd:YAG laser (phase 1 - design)
NASA Technical Reports Server (NTRS)
Foster, J. D.; Kirk, R. F.
1971-01-01
Results of a design study and preliminary design of a space qualified Nd:YAG laser are presented. A theoretical model of the laser was developed to allow the evaluation of the effects of various parameters on its performance. Various pump lamps were evaluated and sum pumping was considered. Cooling requirements were examined and cooling methods such as radiation, cryogenic and conductive were analysed. Power outputs and efficiences of various configurations and the pump and laser lifetime are discussed. Also considered were modulation and modulating methods.
Development of CCD imaging sensors for space applications, phase 1
NASA Technical Reports Server (NTRS)
Antcliffe, G. A.
1975-01-01
The results of an experimental investigation to develop a large area charge coupled device (CCD) imager for space photography applications are described. Details of the design and processing required to achieve 400 X 400 imagers are presented together with a discussion of the optical characterization techniques developed for this program. A discussion of several aspects of large CCD performance is given with detailed test reports. The areas covered include dark current, uniformity of optical response, square wave amplitude response, spectral responsivity and dynamic range.
Alternate space shuttle concepts study: Design requirements and phased programs evaluation
NASA Technical Reports Server (NTRS)
1971-01-01
A study to determine program and technical alternatives to the design of the space shuttle orbiter is described. The alternatives include a phased approach, involving orbiter development and operation with an expendable booster for an interim period, as well as design variations to the basic vehicle. The space shuttle orbiter configurations and predicted performance parameters are presented.
Space Fission Propulsion Testing and Development Progress. Phase 1
NASA Technical Reports Server (NTRS)
VanDyke, Melissa; Houts, Mike; Pedersen, Kevin; Godfroy, Tom; Dickens, Ricky; Poston, David; Reid, Bob; Salvail, Pat; Ring, Peter; Rodgers, Stephen L. (Technical Monitor)
2001-01-01
Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. Testing can be divided into two categories, non-nuclear tests and nuclear tests. Full power nuclear tests of space fission systems we expensive, time consuming, and of limited use, even in the best of programmatic environments. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. Non-nuclear tests are affordable and timely, and the cause of component and system failures can be quickly and accurately identified. MSFC is leading a Safe Affordable Fission Engine (SAFE) test series whose ultimate goal is the demonstration of a 300 kW flight configuration system using non-nuclear testing. This test series is carried out in collaboration with other NASA centers, other government agencies, industry, and universities. If SAFE-related nuclear tests are desired they will have a high probability of success and can be performed at existing nuclear facilities. The paper describes the SAFE non-nuclear test series, which includes test article descriptions, test results and conclusions, and future test plans.
Phase 1 space fission propulsion system testing and development progress
NASA Astrophysics Data System (ADS)
van Dyke, Melissa; Houts, Mike; Pedersen, Kevin; Godfroy, Tom; Dickens, Ricky; Poston, David; Reid, Bob; Salvail, Pat; Ring, Peter
2001-02-01
Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. Testing can be divided into two categories, non-nuclear tests and nuclear tests. Full power nuclear tests of space fission systems are expensive, time consuming, and of limited use, even in the best of programmatic environments. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. Non-nuclear tests are affordable and timely, and the cause of component and system failures can be quickly and accurately identified, MSFC is leading a Safe Affordable Fission Engine (SAFE) test series whose ultimate goal is the demonstration of a 300 kW flight configuration system using non-nuclear testing. This test series is carried out in collaboration with other NASA centers, other government agencies, industry, and universities. If SAFE-related nuclear tests are desired, they will have a high probability of success and can be performed at existing nuclear facilities. The paper describes the SAFE non-nuclear test series, which includes test article descriptions, test results and conclusions, and future test plans. .
Phase 1 Space Fission Propulsion Energy Source Design
NASA Technical Reports Server (NTRS)
Houts, Mike; VanDyke, Melissa; Godfroy, Tom; Pedersen, Kevin; Martin, James; Dickens, Ricky; Salvail, Pat; Hrbud, Ivana; Carter, Robert; Rodgers, Stephen L. (Technical Monitor)
2002-01-01
Fission technology can enable rapid, affordable access to any point in the solar system. If fission propulsion systems are to be developed to their full potential; however, near-term customers must be identified and initial fission systems successfully developed, launched, and operated. Studies conducted in fiscal year 2001 (IISTP, 2001) show that fission electric propulsion (FEP) systems with a specific mass at or below 50 kg/kWjet could enhance or enable numerous robotic outer solar system missions of interest. At the required specific mass, it is possible to develop safe, affordable systems that meet mission requirements. To help select the system design to pursue, eight evaluation criteria were identified: system integration, safety, reliability, testability, specific mass, cost, schedule, and programmatic risk. A top-level comparison of four potential concepts was performed: a Testable, Passive, Redundant Reactor (TPRR), a Testable Multi-Cell In-Core Thermionic Reactor (TMCT), a Direct Gas Cooled Reactor (DGCR), and a Pumped Liquid Metal Reactor.(PLMR). Development of any of the four systems appears feasible. However, for power levels up to at least 500 kWt (enabling electric power levels of 125-175 kWe, given 25-35% power conversion efficiency) the TPRR has advantages related to several criteria and is competitive with respect to all. Hardware-based research and development has further increased confidence in the TPRR approach. Successful development and utilization of a "Phase I" fission electric propulsion system will enable advanced Phase 2 and Phase 3 systems capable of providing rapid, affordable access to any point in the solar system.
Modeling of recombinant yeast cells: reduction of phase space.
Birol, G; Birol, I; Kirdar, B; Onsan, Z I
1997-01-01
The mechanism of starch fermentation by recombinant Saccharomyces cerevisiae in batch reactor is studied. Experiments were carried in the presence and absence of oxygen, with different initial starch concentrations. A variety of data concerning biotic and abiotic phases are collected. Nonlinear data analysis techniques are used to determine the block diagram of the system under study. Data analysis and processing reported here, are believed to form a basis in further work in structured modeling of biological systems, recombinant yeast cultures in particular. PMID:9603032
Natural environment design criteria for the space station program definition phase
NASA Technical Reports Server (NTRS)
Vaughan, W. W.
1984-01-01
The natural environment design criteria requirements for use in the Space Station and its Elements (SSPE) definition phase studies are presented. The atmospheric dynamic and thermodynamic environments, meteoroids, radiation, physical constants are addressed. It is intended to enable all groups involved in the definition phase studies to proceed with a common and consistent set of natural environment criteria requirements.
PARAS program: Phased array radio astronomy from space
NASA Technical Reports Server (NTRS)
Jakubowski, Antoni K.; Haynes, David A.; Nuss, Ken; Hoffmann, Chris; Madden, Michael; Dungan, Michael
1992-01-01
An orbiting radio telescope is proposed which, when operated in a Very Long Baseline Interferometry (VLBLI) scheme, would allow higher (than currently available) angular resolution and dynamic range in the maps, and the ability of observing rapidly changing astronomical sources. Using a passive phases array technology, the proposed design consists of 656 hexagonal modules forming a 150 meter diameter dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data is transmitted to telemetry stations on the ground. The truss frame supporting each observatory pane is a hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and bottom triangle. Attitude control and stationkeeping functions are performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and six hydrazine arcjets, the latter supported by a nuclear reactor. The total mass of the spacecraft is 22,060 kg.
Project PARAS: Phased array radio astronomy from space
NASA Technical Reports Server (NTRS)
Nuss, Kenneth; Hoffmann, Christopher; Dungan, Michael; Madden, Michael; Bendakhlia, Monia
1992-01-01
An orbiting radio telescope is proposed which, when operated in a very long baseline interferometry (VLBI) scheme, would allow higher than currently available angular resolution and dynamic range in the maps and the ability to observe rapidly changing astronomical sources. Using passive phased array technology, the proposed design consists of 656 hexagonal modules forming a 150-m diameter antenna dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data are transmitted to telemetry stations on the ground. The truss frame supporting each observatory panel is a novel hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and the bottom triangle. Attitude control and station keeping functions will be performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and four hydrazine arcjets, the latter supported by either a photovoltaic array or a radioisotope thermoelectric generator. The total mass of the spacecraft is about 20,500 kg.
Space shuttle electromagnetic environment experiment. Phase A: Definition study
NASA Technical Reports Server (NTRS)
Haber, F.; Showers, R. M.; Kocher, C.; Forrest, L. A., Jr.
1976-01-01
Methods for carrying out measurements of earth electromagnetic environment using the space shuttle as a measurement system platform are herein reported. The goal is to provide means for mapping intentional and nonintentional emitters on earth in the frequency range 0.4 to 40 GHz. A survey was made of known emitters using available data from national and international regulatory agencies, and from industry sources. The spatial distribution of sources, power levels, frequencies, degree of frequency re-use, etc., found in the survey, are here presented. A concept is developed for scanning the earth using a directive antenna whose beam is made to rotate at a fixed angle relative to the nadir; the illuminated area swept by the beam is of the form of cycloidal annulus over a sphere. During the beam's sojourn over a point, the receiver sweeps in frequency over ranges in the order of octave width using sweeping filter bandwidths sufficient to give stable readings.
Free-space microwave power transmission study, phase 3
NASA Technical Reports Server (NTRS)
Brown, W. C.
1975-01-01
The results of an investigation of the technology of free-space power transmission by microwave beam are presented. A description of the steps that were taken to increase the overall dc to dc efficiency of microwave power transmission from 15 percent to over 50 percent is given. Included in this overall efficiency were the efficiencies of the dc to microwave conversion, the microwave transmission itself, and the microwave to dc conversion. Improvements in launching the microwave beam with high efficiency by means of a dual mode horn resulted in 95 percent of the output of the microwave generator reaching the receiving area. Emphasis was placed upon successive improvements in reception and rectification of the microwave power, resulting in the design of a rectenna device for this purpose whose efficiency was 75 percent. The procedures and the hardware developed were the basis for tests certified by the Jet Propulsion Laboratory in which an overall dc to dc efficiency of 54 percent was achieved.
Phase-space representation and polarization domains of random electromagnetic fields.
Castaneda, Roman; Betancur, Rafael; Herrera, Jorge; Carrasquilla, Juan
2008-08-01
The phase-space representation of stationary random electromagnetic fields is developed by using electromagnetic spatial coherence wavelets. The propagation of the field's power and states of spatial coherence and polarization results from correlations between the components of the field vectors at pairs of points in space. Polarization domains are theoretically predicted as the structure of the field polarization at the observation plane. In addition, the phase-space representation provides a generalization of the Poynting theorem. Theoretical predictions are examined by numerically simulating the Young experiment with electromagnetic waves. The experimental implementation of these results is a current subject of research. PMID:18670539
3D imaging of translucent media with a plenoptic sensor based on phase space optics
NASA Astrophysics Data System (ADS)
Zhang, Xuanzhe; Shu, Bohong; Du, Shaojun
2015-05-01
Traditional stereo imaging technology is not working for dynamical translucent media, because there are no obvious characteristic patterns on it and it's not allowed using multi-cameras in most cases, while phase space optics can solve the problem, extracting depth information directly from "space-spatial frequency" distribution of the target obtained by plenoptic sensor with single lens. This paper discussed the presentation of depth information in phase space data, and calculating algorithms with different transparency. A 3D imaging example of waterfall was given at last.
Space observations of cold-cloud phase change
Choi, Yong-Sang; Lindzen, Richard S.; Ho, Chang-Hoi; Kim, Jinwon
2010-01-01
This study examines the vertically resolved cloud measurements from the cloud-aerosol lidar with orthogonal polarization instrument on Aqua satellite from June 2006 through May 2007 to estimate the extent to which the mixed cloud-phase composition can vary according to the ambient temperature, an important concern for the uncertainty in calculating cloud radiative effects. At -20 °C, the global average fraction of supercooled clouds in the total cloud population is found to be about 50% in the data period. Between -10 and -40 °C, the fraction is smaller at lower temperatures. However, there are appreciable regional and temporal deviations from the global mean (> ± 20%) at the isotherm. In the analysis with coincident dust aerosol data from the same instrument, it appears that the variation in the supercooled cloud fraction is negatively correlated with the frequencies of dust aerosols at the -20 °C isotherm. This result suggests a possibility that dust particles lifted to the cold cloud layer effectively glaciate supercooled clouds. Observations of radiative flux from the clouds and earth’s radiant energy system instrument aboard Terra satellite, as well as radiative transfer model simulations, show that the 20% variation in the supercooled cloud fraction is quantitatively important in cloud radiative effects, especially in shortwave, which are 10 - 20 W m-2 for regions of mixed-phase clouds affected by dust. In particular, our results demonstrate that dust, by glaciating supercooled water, can decrease albedo, thus compensating for the increase in albedo due to the dust aerosols themselves. This has important implications for the determination of climate sensitivity. PMID:20534562
The space time variety of the hyperradiance from phase-locked soliton oscillators
NASA Astrophysics Data System (ADS)
Lin, Chang; Lin, Mai-mai
2008-12-01
The hyperradiance from phase-locked soliton oscillators is investigated by using the numerical simulation method for the perturbed sine-Gordon equation. Space-time variety for the emitted power from phase-locked soliton oscillators have been diffusely exhibited for the two magnetically coupled long Josephson junctions, operated in singlefluxon modes and involving the family of solutions. We derive some simulation results of space-time character, having the extensive physics meaning, for the theory for superradiance from phase-locked oscillators.
LONGITUDINAL PHASE SPACE CHARACTERIZATION OF ELECTRON BUNCHES AT THE JLAB FEL FACILITY
Shukui Zhang; Stephen Benson; David Douglas; David Hardy; George Neil; Michelle D. Shinn
2006-08-27
We report longitudinal phase space measurements of short electron bunches at the 10kW Free-Electron Laser Facility at Jefferson Lab using broadband synchrotron radiation and a remotely controlled fast streak camera. Accurate measurements are possible because the optical transport system uses only reflective components that do not introduce dispersion. The evolution of longitudinal phase space of the electron beam can be observed in real time while phases of accelerator RF components are being adjusted. This fast and efficient diagnostic enhances the suite of machine setup tools available to JLab FEL operators and applies to other accelerators. The results for certain beam setups will be presented.
Energy content of stormtime ring current from phase space mapping simulations
Chen, M.W.; Schulz, M.; Lyons, L.R.
1993-08-20
The authors perform a model study to account for the increase in energy content of the trapped-particle population which occurs during the main phase of major geomagnetic storms. They consider stormtime particle transport in the equatorial region of the magnetosphere. They start with a phase space distribution of the ring current before the storm, created by a steady state transport model. They then use a previously developed guiding center particle simulation to map the stormtime ring current phase space, following Liouville's theorem. This model is able to account for the ten to twenty fold increase in energy content of magnetospheric ions during the storm.
The effective two-dimensional phase space of cosmological scalar fields
NASA Astrophysics Data System (ADS)
Edwards, David C.
2016-08-01
It has been shown by Remmen and Carroll [1] that, for a model universe which contains only a kinetically canonical scalar field minimally coupled to gravity it is possible to choose `special coordinates' to describe a two-dimensional effective phase space. The special, non-canonical, coordinates are phi,dot phi and the ability to describe an effective phase space with these coordinates empowers the common usage of phi‑dot phi as the space to define inflationary initial conditions. This paper extends the result to the full Horndeski action. The existence of a two-dimensional effective phase space is shown for the general case. Subsets of the Horndeski action, relevant to cosmology are considered as particular examples to highlight important aspects of the procedure.
Phase 1 Space Fission Propulsion System Testing and Development Progress
NASA Technical Reports Server (NTRS)
VanDyke, Melissa; Houts, Mike; Godfroy, Tom; Dickens, Ricky; Poston, David; Kapernick, Rick; Reid, Bob; Salvail, Pat; Ring, Peter; Schafer, Charles (Technical Monitor)
2001-01-01
Successful development of space fission systems requires an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. The Safe Affordable Fission Engine (SAFE) test series, whose ultimate goal is the demonstration of a 300 kW flight configuration system, has demonstrated that realistic testing can be performed using non-nuclear methods. This test series, carried out in collaboration with other NASA centers, other government agencies, industry, and universities, successfully completed a testing program with a 30 kWt core, Stirling engine, and ion engine configuration. Additionally, a 100 kWt core is in fabrication and appropriate test facilities are being reconfigured. This paper describes the current SAFE non-nuclear tests, which includes test article descriptions, test results and conclusions, and future test plans.
Phase 1 space fission propulsion system testing and development progress
NASA Astrophysics Data System (ADS)
van Dyke, Melissa; Houts, Mike; Godfroy, Tom; Dickens, Ricky; Poston, David; Kapernick, Rick; Reid, Bob; Salvail, Pat; Ring, Peter
2002-01-01
Successful development of space fission systems requires an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. The Safe Affordable Fission Engine (SAFE) test series, whose ultimate goal is the demonstration of a 300 kW flight configuration system, has demonstrated that realistic testing can be performed using non-nuclear methods. This test series, carried out in collaboration with other NASA centers, other government agencies, industry, and universities, successfully completed a testing program with a 30 kWt core. Stirling engine, and ion engine configuration. Additionally, a 100 kWt core is in fabrication and appropriate test facilities are being reconfigured. This paper describes the current SAFE non-nuclear tests, which includes test article descriptions, test results and conclusions, and future test plans. .
Phase 1 space fission propulsion system testing and development progress
NASA Astrophysics Data System (ADS)
Dyke, Melissa Van; Houts, Mike; Godfroy, Tom; Dickens, Ricky; Poston, David; Kapernick, Rick; Reid, Bob; Salvail, Pat; Ring, Peter
2002-01-01
Successful development of space fission systems requires an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. The Safe Affordable Fission Engine (SAFE) test series, whose ultimate goal is the demonstration of a 300 kW flight configuration system, has demonstrated that realistic testing can be performed using non-nuclear methods. This test series, carried out in collaboration with other NASA centers, other government agencies, industry, and universities, successfully completed a testing program with a 30 kWt core. Stirling engine, and ion engine configuration. Additionally, a 100 kWt core is in fabrication and appropriate test facilities are being reconfigured. This paper describes the current SAFE non-nuclear tests, which includes test article descriptions, test results and conclusions, and future test plans.
NASA Astrophysics Data System (ADS)
Meierhenrich, Uwe J.; Cason, Julie R. L.; Szopa, Cyril; Sternberg, Robert; Raulin, François; Thiemann, Wolfram H.-P.; Goesmann, Fred
2013-12-01
The European Space Agency's Rosetta mission was launched in March 2004 in order to reach comet 67P/Churyumov-Gerasimenko by August 2014. The Cometary Sampling and Composition experiment (COSAC) onboard the Rosetta mission's lander "Philae" has been designed for the cometary in situ detection and quantification of organic molecules using gas chromatography coupled to mass spectrometry (GC-MS). The GC unit of COSAC is equipped with eight capillary columns that will each provide a specific stationary phase for molecular separation. Three of these stationary phases will be used to chromatographically resolve enantiomers, as they are composed of liquid polymers of polydimethylsiloxane (PDMS) to which chiral valine or cyclodextrin units are attached. Throughout the ten years of Rosetta's journey through space to reach comet 67P, these liquid stationary phases have been exposed to space vacuum, as the capillary columns within the COSAC unit were not sealed or filled with carrier gas. Long term exposures to space vacuum can cause damage to such liquid stationary phases as key monomers, volatiles, and chiral selectors can be vaporized and lost in transit. We have therefore exposed identical spare units of COSAC's chiral stationary phases over eight years to vacuum conditions mimicking those experienced in space and we have now investigated their resolution capabilities towards different enantiomers both before and after exposure to space vacuum environments. We have observed that enantiomeric resolution capabilities of these chiral liquid enantioselective stationary phases has not been affected by exposure to space vacuum conditions. Thus we conclude that the three chiral stationary phases of the COSAC experiment onboard the Rosetta mission lander "Philae" can be considered to have maintained their resolution capacities throughout their journey prior to cometary landing in November 2014.
Painting phase spaces to put frozen orbits in context
NASA Astrophysics Data System (ADS)
Coffey, S.; Deprit, A.; Deprit, E.
1991-08-01
Frozen orbits are orbits whose average eccentricities and inclinations are constant. It is shown how bifurcations create frozen orbits near the critical inclination at a given energy; in particular how, due to a symmetry breaking when the odd zonal harmonics are admitted in the model, the evolution along the sequences of frozen orbits differs drastically from the one obtained when only the even zonal harmonics are taken in. A model problem involving the first nine zonal harmonics fits very well, according to the findings, the very long term orbital behavior of satellites in the Molnya class; in that model, quite clearly almost circular frozen orbits are detected at low inclinations, and an inclination slightly above the critical one is identified where there exists a circular frozen orbit. The techniques used in this paper are a mix of symbolic manipulations by computers, global representation of phase flow in color by means of massively parallel processors, and interaction between graphics and numerical analysis at the screen of a workstation.
NASA Technical Reports Server (NTRS)
Peters, Bruce; Wingo, Dennis; Bower, Mark; Amborski, Robert; Blount, Laura; Daniel, Alan; Hagood, Bob; Handley, James; Hediger, Donald; Jimmerson, Lisa
1990-01-01
The separation of fluid phases in microgravity environments is of importance to environmental control and life support systems (ECLSS) and materials processing in space. A successful fluid phase separation experiment will demonstrate a proof of concept for the separation technique and add to the knowledge base of material behavior. The phase separation experiment will contain a premixed fluid which will be exposed to a microgravity environment. After the phase separation of the compound has occurred, small samples of each of the species will be taken for analysis on the Earth. By correlating the time of separation and the temperature history of the fluid, it will be possible to characterize the process. The experiment has been integrated into space available on a manifested Get Away Special (GAS) experiment, CONCAP 2, part of the Consortium for Materials Complex Autonomous Payload (CAP) Program, scheduled for STS-42. The design and the production of a fluid phase separation experiment for rapid implementation at low cost is presented.
Performance evaluation of digital phase-locked loops for advanced deep space transponders
NASA Technical Reports Server (NTRS)
Nguyen, T. M.; Hinedi, S. M.; Yeh, H.-G.; Kyriacou, C.
1994-01-01
The performances of the digital phase-locked loops (DPLL's) for the advanced deep-space transponders (ADT's) are investigated. DPLL's considered in this article are derived from the analog phase-locked loop, which is currently employed by the NASA standard deep space transponder, using S-domain to Z-domain mapping techniques. Three mappings are used to develop digital approximations of the standard deep space analog phase-locked loop, namely the bilinear transformation (BT), impulse invariant transformation (IIT), and step invariant transformation (SIT) techniques. The performance in terms of the closed loop phase and magnitude responses, carrier tracking jitter, and response of the loop to the phase offset (the difference between in incoming phase and reference phase) is evaluated for each digital approximation. Theoretical results of the carrier tracking jitter for command-on and command-off cases are then validated by computer simulation. Both theoretical and computer simulation results show that at high sampling frequency, the DPLL's approximated by all three transformations have the same tracking jitter. However, at low sampling frequency, the digital approximation using BT outperforms the others. The minimum sampling frequency for adequate tracking performance is determined for each digital approximation of the analog loop. In addition, computer simulation shows that the DPLL developed by BT provides faster response to the phase offset than IIT and SIT.
Looking for phase-space structures in star-forming regions: an MST-based methodology
NASA Astrophysics Data System (ADS)
Alfaro, Emilio J.; González, Marta
2016-03-01
We present a method for analysing the phase space of star-forming regions. In particular we are searching for clumpy structures in the 3D sub-space formed by two position coordinates and radial velocity. The aim of the method is the detection of kinematic segregated radial velocity groups, that is, radial velocity intervals whose associated stars are spatially concentrated. To this end we define a kinematic segregation index, tilde{Λ }(RV), based on the Minimum Spanning Tree graph algorithm, which is estimated for a set of radial velocity intervals in the region. When tilde{Λ }(RV) is significantly greater than 1 we consider that this bin represents a grouping in the phase space. We split a star-forming region into radial velocity bins and calculate the kinematic segregation index for each bin, and then we obtain the spectrum of kinematic groupings, which enables a quick visualization of the kinematic behaviour of the region under study. We carried out numerical models of different configurations in the sub-space of the phase space formed by the coordinates and the that various case studies illustrate. The analysis of the test cases demonstrates the potential of the new methodology for detecting different kind of groupings in phase space.
Temperature and phase-space density of a cold atom cloud in a quadrupole magnetic trap
NASA Astrophysics Data System (ADS)
Ram, S. P.; Mishra, S. R.; Tiwari, S. K.; Rawat, H. S.
2014-08-01
We present studies on modifications in the temperature, number density and phase-space density when a laser-cooled atom cloud from optical molasses is trapped in a quadrupole magnetic trap. Theoretically, for a given temperature and size of the cloud from the molasses, the phase-space density in the magnetic trap is shown first to increase with increasing magnetic field gradient and then to decrease with it after attaining a maximum value at an optimum value of the magnetic-field gradient. The experimentally-measured variation in the phase-space density in the magnetic trap with changing magnetic field gradient is shown to exhibit a similar trend. However, the experimentally-measured values of the number density and the phase-space density are much lower than the theoretically-predicted values. This is attributed to the experimentally-observed temperature in the magnetic trap being higher than the theoretically-predicted temperature. Nevertheless, these studies can be useful for setting a higher phase-space density in the trap by establishing an optimal value of the field gradient for a quadrupole magnetic trap.
NASA Astrophysics Data System (ADS)
Zhang, M.; Zou, W.; Chen, T.; Kim, L.; Khan, A.; Haffty, B.; Yue, N. J.
2014-01-01
A common approach to implementing the Monte Carlo method for the calculation of brachytherapy radiation dose deposition is to use a phase space file containing information on particles emitted from a brachytherapy source. However, the loading of the phase space file during the dose calculation consumes a large amount of computer random access memory, imposing a higher requirement for computer hardware. In this study, we propose a method to parameterize the information (e.g., particle location, direction and energy) stored in the phase space file by using several probability distributions. This method was implemented for dose calculations of a commercial Ir-192 high dose rate source. Dose calculation accuracy of the parameterized source was compared to the results observed using the full phase space file in a simple water phantom and in a clinical breast cancer case. The results showed the parameterized source at a size of 200 kB was as accurate as the phase space file represented source of 1.1 GB. By using the parameterized source representation, a compact Monte Carlo job can be designed, which allows an easy setup for parallel computing in brachytherapy planning.
Spaced-antenna wind estimation using an X-band active phased-array weather radar
NASA Astrophysics Data System (ADS)
Venkatesh, Vijay
Over the past few decades, several single radar methods have been developed to probe the kinematic structure of storms. All these methods trade angular-resolution to retrieve the wind-field. To date, the spaced-antenna method has been employed for profiling the ionosphere and the precipitation free lower atmosphere. This work focuses on applying the spaced-antenna method on an X-band active phased-array radar for high resolution horizontal wind-field retrieval from precipitation echoes. The ability to segment the array face into multiple displaced apertures allows for flexible spaced-antenna implementations. The methodology employed herein comprises of Monte-Carlo simulations to optimize the spaced-antenna system design and analysis of real data collected with the designed phased-array system. The contribution that underpins this dissertation is the demonstration of qualitative agreement between spaced-antenna and Doppler beam swinging retrievals based on real data. First, simulations of backscattered electric fields at the antenna array elements are validated using theoretical expressions. Based on the simulations, the degrees of freedom in the spaced-antenna system design are optimized for retrieval of mean baseline wind. We show that the designed X-band spaced-antenna system has lower retrieval uncertainty than the existing S-band spaced-antenna implementation on the NWRT. This is because of the flexibility to synthesize small overlapping apertures and the ability to obtain statistically independent samples at a faster rate at X-band. We then demonstrate a technique to make relative phase-center displacement measurements based on simulations and real data from the phased-array spaced-antenna system. This simple method uses statistics of precipitation echoes and apriori beamwidth measurements to make field repeatable phase-center displacement measurements. Finally, we test the hypothesis that wind-field curvature effects are common to both the spaced-antenna and
Quantum phase-space picture of Bose-Einstein condensates in a double well
Mahmud, Khan W.; Perry, Heidi; Reinhardt, William P.
2005-02-01
We present a quantum phase-space model of the Bose-Einstein condensate (BEC) in a double-well potential. In a quantum two-mode approximation we examine the eigenvectors and eigenvalues and find that the energy correlation diagram indicates a transition from a delocalized to a fragmented regime. Phase-space information is extracted from the stationary quantum states using the Husimi distribution function. We show that the mean-field phase-space characteristics of a nonrigid physical pendulum arises from the exact quantum states, and that only 4-8 particles per well are needed to reach the semiclassical limit. For a driven double-well BEC, we show that the classical chaotic dynamics is manifest in the dynamics of the quantum states. Phase-space analogy also suggests that a {pi} phase-displaced wave packet put on the unstable fixed point on a separatrix bifurcates to create a superposition of two pendulum rotor states--a macroscopic superposition state of BEC. We show that the choice of initial barrier height and ramping, following a {pi} phase imprinting on the condensate, can be used to generate controlled entangled number states with tunable extremity and sharpness.
Phase and Pupil Amplitude Recovery for JWST Space-Optics Control
NASA Technical Reports Server (NTRS)
Dean, B. H.; Zielinski, T. P.; Smith, J. S.; Bolcar, M. R.; Aronstein, D. L.; Fienup, J. R.
2010-01-01
This slide presentation reviews the phase and pupil amplitude recovery for the James Webb Space Telescope (JWST) Near Infrared Camera (NIRCam). It includes views of the Integrated Science Instrument Module (ISIM), the NIRCam, examples of Phase Retrieval Data, Ghost Irradiance, Pupil Amplitude Estimation, Amplitude Retrieval, Initial Plate Scale Estimation using the Modulation Transfer Function (MTF), Pupil Amplitude Estimation vs lambda, Pupil Amplitude Estimation vs. number of Images, Pupil Amplitude Estimation vs Rotation (clocking), and Typical Phase Retrieval Results Also included is information about the phase retrieval approach, Non-Linear Optimization (NLO) Optimized Diversity Functions, and Least Square Error vs. Starting Pupil Amplitude.
3D imaging in volumetric scattering media using phase-space measurements.
Liu, Hsiou-Yuan; Jonas, Eric; Tian, Lei; Zhong, Jingshan; Recht, Benjamin; Waller, Laura
2015-06-01
We demonstrate the use of phase-space imaging for 3D localization of multiple point sources inside scattering material. The effect of scattering is to spread angular (spatial frequency) information, which can be measured by phase space imaging. We derive a multi-slice forward model for homogenous volumetric scattering, then develop a reconstruction algorithm that exploits sparsity in order to further constrain the problem. By using 4D measurements for 3D reconstruction, the dimensionality mismatch provides significant robustness to multiple scattering, with either static or dynamic diffusers. Experimentally, our high-resolution 4D phase-space data is collected by a spectrogram setup, with results successfully recovering the 3D positions of multiple LEDs embedded in turbid scattering media. PMID:26072807
High-order continuum kinetic method for modeling plasma dynamics in phase space
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-12-15
Continuum methods offer a high-fidelity means of simulating plasma kinetics. While computationally intensive, these methods are advantageous because they can be cast in conservation-law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Advances in continuum method capabilities for modeling kinetic phenomena in plasmas require the development of validation tools in higher dimensional phase space and an ability to handle non-cartesian geometries. To that end, a new benchmark for validating Vlasov-Poisson simulations in 3D (x,vx,vy) is presented. The benchmark is based on the Dory-Guest-Harris instability and is successfully used to validate a continuum finite volumemore » algorithm. To address challenges associated with non-cartesian geometries, unique features of cylindrical phase space coordinates are described. Preliminary results of continuum kinetic simulations in 4D (r,z,vr,vz) phase space are presented.« less
Unified matrix approach to the description of phase-space rotators.
Gitin, Andrey V
2016-03-01
In optics, the rotation of a phase-space can be realized via light propagation through both an inhomogeneous medium with a radial gradient of refractive index and two special kinds of mirror-symmetrical optical systems suggested by Lohmann. Although light propagation through Lohmann's systems is described in terms of matrix optics, light propagation through the gradient-index medium is traditionally described as a solution of the wave equation. The difference in these descriptions hinders the understanding of the phase-space rotators. Fortunately, there is a matrix description of light propagation through a gradient-index medium too. A general description of the phase-space rotators is presented, which can be used to treat light propagation through both Lohmann's systems and the gradient-index medium in a unified matrix manner. PMID:26974609
Space shuttle main engine definition (phase B). Volume 2: Avionics. [for space shuttle
NASA Technical Reports Server (NTRS)
1971-01-01
The advent of the space shuttle engine with its requirements for high specific impulse, long life, and low cost have dictated a combustion cycle and a closed loop control system to allow the engine components to run close to operating limits. These performance requirements, combined with the necessity for low operational costs, have placed new demands on rocket engine control, system checkout, and diagnosis technology. Based on considerations of precision environment, and compatibility with vehicle interface commands, an electronic control, makes available many functions that logically provide the information required for engine system checkout and diagnosis.
Amateur Radio on the International Space Station - Phase 2 Hardware System
NASA Technical Reports Server (NTRS)
Bauer, F.; McFadin, L.; Bruninga, B.; Watarikawa, H.
2003-01-01
The International Space Station (ISS) ham radio system has been on-orbit for over 3 years. Since its first use in November 2000, the first seven expedition crews and three Soyuz taxi crews have utilized the amateur radio station in the Functional Cargo Block (also referred to as the FGB or Zarya module) to talk to thousands of students in schools, to their families on Earth, and to amateur radio operators around the world. Early on, the Amateur Radio on the International Space Station (ARISS) international team devised a multi-phased hardware development approach for the ISS ham radio station. Three internal development Phases. Initial Phase 1, Mobile Radio Phase 2 and Permanently Mounted Phase 3 plus an externally mounted system, were proposed and agreed to by the ARISS team. The Phase 1 system hardware development which was started in 1996 has since been delivered to ISS. It is currently operational on 2 meters. The 70 cm system is expected to be installed and operated later this year. Since 2001, the ARISS international team have worked to bring the second generation ham system, called Phase 2, to flight qualification status. At this time, major portions of the Phase 2 hardware system have been delivered to ISS and will soon be installed and checked out. This paper intends to provide an overview of the Phase 1 system for background and then describe the capabilities of the Phase 2 radio system. It will also describe the current plans to finalize the Phase 1 and Phase 2 testing in Russia and outlines the plans to bring the Phase 2 hardware system to full operation.
The fault monitoring and diagnosis knowledge-based system for space power systems: AMPERES, phase 1
NASA Technical Reports Server (NTRS)
Lee, S. C.
1989-01-01
The objective is to develop a real time fault monitoring and diagnosis knowledge-based system (KBS) for space power systems which can save costly operational manpower and can achieve more reliable space power system operation. The proposed KBS was developed using the Autonomously Managed Power System (AMPS) test facility currently installed at NASA Marshall Space Flight Center (MSFC), but the basic approach taken for this project could be applicable for other space power systems. The proposed KBS is entitled Autonomously Managed Power-System Extendible Real-time Expert System (AMPERES). In Phase 1 the emphasis was put on the design of the overall KBS, the identification of the basic research required, the initial performance of the research, and the development of a prototype KBS. In Phase 2, emphasis is put on the completion of the research initiated in Phase 1, and the enhancement of the prototype KBS developed in Phase 1. This enhancement is intended to achieve a working real time KBS incorporated with the NASA space power system test facilities. Three major research areas were identified and progress was made in each area. These areas are real time data acquisition and its supporting data structure; sensor value validations; development of inference scheme for effective fault monitoring and diagnosis, and its supporting knowledge representation scheme.
Evolution of electron beam phase space distribution in a high-gain FEL
Webb,S.D.; Litvinenko, V. N.
2009-08-23
FEL-based coherent electron cooling (CEC) offers a new avenue to achieve high luminosities in high energy colliders such as RHIC, LHC, and eRHIC. Traditional treatments consider the FEL as an amplifier of optical waves with specific initial conditions, focusing on the resulting field. CEC requires knowledge of the phase space distribution of the electron beam in the FEL. We present 1D analytical results for the phase space distribution of an electron beam with an arbitrary initial current profile, and discuss approaches of expanding to 3D results.
Nonlinear satellite wakes in planetary rings. I - Phase-space kinematics
NASA Technical Reports Server (NTRS)
Stewart, Glen R.
1991-01-01
The explicit expression presently derived for the phase-space density of a planetary ring subjected to perturbations by a proximate satellite recovers the usual perturbed-streamline equations by drawing first-order moments of the phase-space density. The surface density obtained is positive-definite in virtue of taking the ring particles' finite-velocity dispersion into account. The satellite-wake local mean velocity components deviate from the streamline equations' sinusoidal form; this deviation grows as the wake moves downstream from the shepherding satellite.
Phase-space dynamics of ionization injection in plasma-based accelerators.
Xu, X L; Hua, J F; Li, F; Zhang, C J; Yan, L X; Du, Y C; Huang, W H; Chen, H B; Tang, C X; Lu, W; Yu, P; An, W; Joshi, C; Mori, W B
2014-01-24
The evolution of beam phase space in ionization injection into plasma wakefields is studied using theory and particle-in-cell simulations. The injection process involves both longitudinal and transverse phase mixing, leading initially to a rapid emittance growth followed by oscillation, decay, and a slow growth to saturation. An analytic theory for this evolution is presented and verified through particle-in-cell simulations. This theory includes the effects of injection distance (time), acceleration distance, wakefield structure, and nonlinear space charge forces, and it also shows how ultralow emittance beams can be produced using ionization injection methods. PMID:24484147
GPU-based Monte Carlo radiotherapy dose calculation using phase-space sources
NASA Astrophysics Data System (ADS)
Townson, Reid W.; Jia, Xun; Tian, Zhen; Jiang Graves, Yan; Zavgorodni, Sergei; Jiang, Steve B.
2013-06-01
A novel phase-space source implementation has been designed for graphics processing unit (GPU)-based Monte Carlo dose calculation engines. Short of full simulation of the linac head, using a phase-space source is the most accurate method to model a clinical radiation beam in dose calculations. However, in GPU-based Monte Carlo dose calculations where the computation efficiency is very high, the time required to read and process a large phase-space file becomes comparable to the particle transport time. Moreover, due to the parallelized nature of GPU hardware, it is essential to simultaneously transport particles of the same type and similar energies but separated spatially to yield a high efficiency. We present three methods for phase-space implementation that have been integrated into the most recent version of the GPU-based Monte Carlo radiotherapy dose calculation package gDPM v3.0. The first method is to sequentially read particles from a patient-dependent phase-space and sort them on-the-fly based on particle type and energy. The second method supplements this with a simple secondary collimator model and fluence map implementation so that patient-independent phase-space sources can be used. Finally, as the third method (called the phase-space-let, or PSL, method) we introduce a novel source implementation utilizing pre-processed patient-independent phase-spaces that are sorted by particle type, energy and position. Position bins located outside a rectangular region of interest enclosing the treatment field are ignored, substantially decreasing simulation time with little effect on the final dose distribution. The three methods were validated in absolute dose against BEAMnrc/DOSXYZnrc and compared using gamma-index tests (2%/2 mm above the 10% isodose). It was found that the PSL method has the optimal balance between accuracy and efficiency and thus is used as the default method in gDPM v3.0. Using the PSL method, open fields of 4 × 4, 10 × 10 and 30 × 30 cm
NASA Technical Reports Server (NTRS)
Roberts, B. C.; Carrasquillo, R. L.; Dubiel, M. Y.; Ogle, K. Y.; Perry, J. L.; Whitley, K. M.
1990-01-01
A description of the phase 3 simplified integrated test (SIT) conducted at the Marshall Space Flight Center (MSFC) Core Module Integration Facility (CMIF) in 1989 is presented. This was the first test in the phase 3 series integrated environmental control and life support systems (ECLSS) tests. The basic goal of the SIT was to achieve full integration of the baseline air revitalization (AR) subsystems for Space Station Freedom. Included is a description of the SIT configuration, a performance analysis of each subsystem, results from air and water sampling, and a discussion of lessons learned from the test. Also included is a full description of the preprototype ECLSS hardware used in the test.
A Gaussian wave packet phase-space representation of quantum canonical statistics
Coughtrie, David J.; Tew, David P.
2015-07-28
We present a mapping of quantum canonical statistical averages onto a phase-space average over thawed Gaussian wave-packet (GWP) parameters, which is exact for harmonic systems at all temperatures. The mapping invokes an effective potential surface, experienced by the wave packets, and a temperature-dependent phase-space integrand, to correctly transition from the GWP average at low temperature to classical statistics at high temperature. Numerical tests on weakly and strongly anharmonic model systems demonstrate that thermal averages of the system energy and geometric properties are accurate to within 1% of the exact quantum values at all temperatures.
The application of the phase space time evolution method to electron shielding
NASA Technical Reports Server (NTRS)
Cordaro, M. C.; Zucker, M. S.
1972-01-01
A computer technique for treating the motion of charged and neutral particles and called the phase space time evolution method was developed. This technique employs the computer's bookkeeping capacity to keep track of the time development of a phase space distribution of particles. This method was applied to a study of the penetration of electrons. A 1 MeV beam of electrons normally incident on a semi-infinite slab of aluminum was used. Results of the calculation were compared with Monte Carlo calculations and experimental results. Time-dependent PSTE electron penetration results for the same problem are presented.
GPU-based Monte Carlo radiotherapy dose calculation using phase-space sources.
Townson, Reid W; Jia, Xun; Tian, Zhen; Graves, Yan Jiang; Zavgorodni, Sergei; Jiang, Steve B
2013-06-21
A novel phase-space source implementation has been designed for graphics processing unit (GPU)-based Monte Carlo dose calculation engines. Short of full simulation of the linac head, using a phase-space source is the most accurate method to model a clinical radiation beam in dose calculations. However, in GPU-based Monte Carlo dose calculations where the computation efficiency is very high, the time required to read and process a large phase-space file becomes comparable to the particle transport time. Moreover, due to the parallelized nature of GPU hardware, it is essential to simultaneously transport particles of the same type and similar energies but separated spatially to yield a high efficiency. We present three methods for phase-space implementation that have been integrated into the most recent version of the GPU-based Monte Carlo radiotherapy dose calculation package gDPM v3.0. The first method is to sequentially read particles from a patient-dependent phase-space and sort them on-the-fly based on particle type and energy. The second method supplements this with a simple secondary collimator model and fluence map implementation so that patient-independent phase-space sources can be used. Finally, as the third method (called the phase-space-let, or PSL, method) we introduce a novel source implementation utilizing pre-processed patient-independent phase-spaces that are sorted by particle type, energy and position. Position bins located outside a rectangular region of interest enclosing the treatment field are ignored, substantially decreasing simulation time with little effect on the final dose distribution. The three methods were validated in absolute dose against BEAMnrc/DOSXYZnrc and compared using gamma-index tests (2%/2 mm above the 10% isodose). It was found that the PSL method has the optimal balance between accuracy and efficiency and thus is used as the default method in gDPM v3.0. Using the PSL method, open fields of 4 × 4, 10 × 10 and 30 × 30 cm
Free space optical communication link using a silicon photonic optical phased array
NASA Astrophysics Data System (ADS)
Rabinovich, William S.; Goetz, Peter G.; Pruessner, Marcel; Mahon, Rita; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.
2015-03-01
Many components for free space optical communication systems have shrunken in size over the last decade. However, the steering systems have remained large and power hungry. Non-mechanical beam steering offers a path to reducing the size of these systems. Optical phased arrays can allow integrated beam steering elements. One of the most important aspects of an optical phased array technology is its scalability to a large number of elements. Silicon photonics can potentially offer this scalability using CMOS foundry techniques. In this paper a small-scale silicon photonic optical phased array is demonstrated for both the transmitter and receiver functions in a free space optical link. The device using an array of thermo-optically controlled waveguide phase shifters and demonstrates one-dimensional steering with a single control electrode. Transmission of a digitized video data stream over the link is shown.
Phase-space description of plasma waves: Linear and nonlinear theory
NASA Astrophysics Data System (ADS)
Biro, Thomas
1992-11-01
A (r,k) phase description of waves in plasmas is developed by introducing Gaussian window functions to separate short scale oscillations from long scale modulations of the wave fields and variations in the plasma parameters. To obtain a wave equation that unambiguously separates conservative dynamics from dissipation also in an inhomogeneous and time varying background plasma, the proper form of the current response function, is discussed. On the analogy of the particle distribution function f(v,r,t), a wave density N(k,r,t) is introduced on phase space. This function is proven to satisfy a simple continuity equation. Dissipation is also included, and this allows the damping or growth of wave density along rays to be described. Problems involving geometric optics of continuous media often appear simpler when viewed in phase space, since the flow of N in phase space is incompressible. Within the phase space representation, a very general formula for the second order nonlinear current is obtained in terms of the vector potential. This formula is a convenient starting point for studies of coherent as well as turbulent nonlinear processes. Kinetic equations for weakly inhomogeneous and turbulent plasmas are derived, including the effects of inhomogeneous turbulence, wave convection and refraction.
Phased Array Ultrasonic Examination of Space Shuttle Main Engine Nozzle Weld
NASA Technical Reports Server (NTRS)
James, S.; Engel, J.; Kimbrough, D.; Suits, M.; McCool, Alex (Technical Monitor)
2001-01-01
This paper describes a Phased Array Ultrasonic Examination that was developed for the examination of a limited access circumferential Inconel 718 fusion weld of a Space Shuttle Main Engine Nozzle - Cone. The paper discusses the selection and formation criteria used for the phased array focal laws, the reference standard that simulated hardware conditions, the examination concept, and results. Several unique constraints present during this examination included limited probe movement to a single axis and one-sided access to the weld.
Phase space gradient of dissipated work and information: A role of relative Fisher information
Yamano, Takuya
2013-11-15
We show that an information theoretic distance measured by the relative Fisher information between canonical equilibrium phase densities corresponding to forward and backward processes is intimately related to the gradient of the dissipated work in phase space. We present a universal constraint on it via the logarithmic Sobolev inequality. Furthermore, we point out that a possible expression of the lower bound indicates a deep connection in terms of the relative entropy and the Fisher information of the canonical distributions.
Chemical potential driven phase transition of black holes in anti-de Sitter space
NASA Astrophysics Data System (ADS)
Galante, Mario; Giribet, Gaston; Goya, Andrés; Oliva, Julio
2015-11-01
Einstein-Maxwell theory conformally coupled to a scalar field in D dimensions may exhibit a phase transition at low temperature whose end point is an asymptotically anti-de Sitter black hole with a scalar field profile that is regular everywhere outside and on the horizon. This provides a tractable model to study the phase transition of hairy black holes in anti-de Sitter space in which the backreaction on the geometry can be solved analytically.
Space cryogenics components based on the thermomechanical effect - Vapor-liquid phase separation
NASA Technical Reports Server (NTRS)
Yuan, S. W. K.; Frederking, T. H. K.
1989-01-01
Applications of the thermomechanical effect has been qualified including incorporation in large-scale space systems in the area of vapor-liquid phase separation (VLPS). The theory of the porous-plug phase separator is developed for the limit of a high thermal impedance of the solid-state grains. Extensions of the theory of nonlinear turbulent flow are presented based on experimental results.
Extending the scanning angle of a phased array antenna by using a null-space medium.
Sun, Fei; He, Sailing
2014-01-01
By introducing a columnar null-space region as the reference space, we design a radome that can extend the scanning angle of a phased array antenna (PAA) by a predetermined relationship (e.g. a linear relationship between the incident angle and steered output angle can be achieved). After some approximation, we only need two homogeneous materials to construct the proposed radome layer by layer. This kind of medium is called a null-space medium, which has been studied and fabricated for realizing hyper-lenses and some other devices. Numerical simulations verify the performance of our radome. PMID:25355198
Extending the scanning angle of a phased array antenna by using a null-space medium
NASA Astrophysics Data System (ADS)
Sun, Fei; He, Sailing
2014-10-01
By introducing a columnar null-space region as the reference space, we design a radome that can extend the scanning angle of a phased array antenna (PAA) by a predetermined relationship (e.g. a linear relationship between the incident angle and steered output angle can be achieved). After some approximation, we only need two homogeneous materials to construct the proposed radome layer by layer. This kind of medium is called a null-space medium, which has been studied and fabricated for realizing hyper-lenses and some other devices. Numerical simulations verify the performance of our radome.
Extending the scanning angle of a phased array antenna by using a null-space medium
Sun, Fei; He, Sailing
2014-01-01
By introducing a columnar null-space region as the reference space, we design a radome that can extend the scanning angle of a phased array antenna (PAA) by a predetermined relationship (e.g. a linear relationship between the incident angle and steered output angle can be achieved). After some approximation, we only need two homogeneous materials to construct the proposed radome layer by layer. This kind of medium is called a null-space medium, which has been studied and fabricated for realizing hyper-lenses and some other devices. Numerical simulations verify the performance of our radome. PMID:25355198
Phase space localization for anti-de Sitter quantum mechanics and its zero curvature limit
NASA Technical Reports Server (NTRS)
Elgradechi, Amine M.
1993-01-01
Using techniques of geometric quantization and SO(sub 0)(3,2)-coherent states, a notion of optimal localization on phase space is defined for the quantum theory of a massive and spinning particle in anti-de Sitter space time. It is shown that this notion disappears in the zero curvature limit, providing one with a concrete example of the regularizing character of the constant (nonzero) curvature of the anti-de Sitter space time. As a byproduct a geometric characterization of masslessness is obtained.
NASA Technical Reports Server (NTRS)
1974-01-01
The 12 month Phase A Conceptual Design Study of the Atmospheric, Magnetospheric and Plasmas in Space (AMPS) payload performed within the Program Development Directorate of the Marshall Space Flight Center is presented. The AMPS payload makes use of the Spacelab pressurized module and pallet, is launched by the space shuttle, and will have initial flight durations of 7 days. Scientific instruments including particle accelerators, high power transmitters, optical instruments, and chemical release devices are mounted externally on the Spacelab pallet and are controlled by the experimenters from within the pressurized module. The capability of real-time scientist interaction on-orbit with the experiment is a major characteristic of AMPS.
Holographic phase space: c-functions and black holes as renormalization group flows
NASA Astrophysics Data System (ADS)
Paulos, Miguel F.
2011-05-01
We construct a mathcal{N} -function for Lovelock theories of gravity, which yields a holographic c-function in domain-wall backgrounds, and seemingly generalizes the concept for black hole geometries. A flow equation equates the monotonicity properties of mathcal{N} with the gravitational field, which has opposite signs in the domain-wall and black hole backgrounds, due to the presence of negative/positive energy in the former/latter, and accordingly mathcal{N} monotonically decreases/increases from the UV to the IR. On AdS spaces the mathcal{N} -function is related to the Euler anomaly, and at a black hole horizon it is generically proportional to the entropy. For planar black holes, mathcal{N} diverges at the horizon, which we interpret as an order N 2 increase in the number of effective degrees of freedom. We show how mathcal{N} can be written as the ratio of the Wald entropy to an effective phase space volume, and using the flow equation relate this to Verlinde's notion of gravity as an entropic force. From the effective phase space we can obtain an expression for the dual field theory momentum cut-off, matching a previous proposal in the literature by Polchinski and Heemskerk. Finally, we propose that the area in Planck units counts states, not degrees of freedom, and identify it also as a phase space volume. Written in terms of the proper radial distance β, it takes the suggestive form of a canonical partition function at inverse temperature β, leading to a "mean energy" which is simply the extrinsic curvature of the surface. Using this we relate this definition of holographic phase space with the effective phase space appearing in the mathcal{N} -function.
Pickup Ion Phase Space Distributions at Titan in a Three Dimensional Exosphere
NASA Technical Reports Server (NTRS)
Hartle, Richard; Sittler, Edward
2006-01-01
The composition and structure of neutral exospheres imbedded in moving plasmas can be determined by measurements of the velocity distributions of their pickup ion progeny. In turn, the velocity distributions are dependent on the spatial structure of the neutral source gases. Since Titan's neutral exosphere extends into the Saturn's magnetosphere (or solar wind) and well above its ionopause, it serves as a good place to analyze such characteristics. They are analyzed using pickup ion measurements made by the Cassini Plasma Spectrometer (CAPS) at Titan [e.g., Hartle et al., 2006] and an ion kinetic model. An early version of the model [Hartle and Sittler, 2007] is an expression describing the phase space density of pickup ions, which is derived from the Vlasov equation with an ion source that explicitly accounts for the velocity and spatial variation of the exosphere source gases. The current version used here includes exosphere source gases in three dimensions. A fundamental parameter of the phase space densities is the ratio of the gyroradius to the neutral scale height alpha, = r(sub g)/H. Titan's exosphere structure yields pickup ions whose phase space distributions are beam-like when alpha >> 1 and fluid-like when alpha << 1. Downstream from the source peak, the light pickup ions, with alpha << 1, are easily observed because their phase space densities are almost uniform over the orbit phases. On the other hand, the phase space distributions of the heavier ions, with alpha >> 1, peak over narrow velocity and spatial ranges. This beam-like nature makes it considerably more difficult to observe heavy ions because their downstream positions and viewing directions are narrowly constrained. Examples of these extremes will be discussed.
Phase-space structure of the Buckingham's two-body problem
NASA Astrophysics Data System (ADS)
Pricopi, D.; Popescu, E.
2016-06-01
In this paper, we study the global flow for the two-body problem associated to the Buckingham potential. For this, using McGehee-type transformations, we write the regularized equations of motion. Then, reducing the 4-dimensional phase space to a 2-dimension one, the global flow in the phase plane is described for all possible values of the parameters of the potential and those of the energy and angular momentum constants. Every phase trajectory is interpreted in terms of physical motion, our problem being depicted both geometrically and physically.
NASA Technical Reports Server (NTRS)
Deuser, Mark S.; Vanalstine, James M.; Vellinger, John C.; Wessling, Francis C.; Lundquist, Charles A.
1992-01-01
Traditional separation techniques are inadequate for many new bioprocessing challenges. Innovative separation methods such as aqueous two phase partitioning are needed to perpetuate bioprocess commercialization. Aqueous two phase polymer partitioning systems provide a process for separating biological materials when combined with microgravity. An innovative space qualified apparatus developed for carrying out separations by partitioning in immiscible polymer systems under mirogravity conditions is described. The apparatus offers an innovative approach to low gravity bioseparations in general and phase partitioning in particular. These capabilities support NASA's interest in serving the biotechnology research community and providing quantitative data in the gravity dependent components of separation processes.
Molecular phase space transport in water: Non-stationary random walk model
NASA Astrophysics Data System (ADS)
Nerukh, Dmitry; Ryabov, Vladimir; Taiji, Makoto
2009-11-01
Molecular transport in phase space is crucial for chemical reactions because it defines how pre-reactive molecular configurations are found during the time evolution of the system. Using Molecular Dynamics (MD) simulated atomistic trajectories we test the assumption of the normal diffusion in the phase space for bulk water at ambient conditions by checking the equivalence of the transport to the random walk model. Contrary to common expectations we have found that some statistical features of the transport in the phase space differ from those of the normal diffusion models. This implies a non-random character of the path search process by the reacting complexes in water solutions. Our further numerical experiments show that a significant long period of non-stationarity in the transition probabilities of the segments of molecular trajectories can account for the observed non-uniform filling of the phase space. Surprisingly, the characteristic periods in the model non-stationarity constitute hundreds of nanoseconds, that is much longer time scales compared to typical lifetime of known liquid water molecular structures (several picoseconds).
Plimak, L.I.; Fleischhauer, M.; Olsen, M.K.; Collett, M.J.
2003-01-01
We present an introduction to phase-space techniques (PST) based on a quantum-field-theoretical (QFT) approach. In addition to bridging the gap between PST and QFT, our approach results in a number of generalizations of the PST. First, for problems where the usual PST do not result in a genuine Fokker-Planck equation (even after phase-space doubling) and hence fail to produce a stochastic differential equation (SDE), we show how the system in question may be approximated via stochastic difference equations (S{delta}E). Second, we show that introducing sources into the SDE's (or S{delta}E's) generalizes them to a full quantum nonlinear stochastic response problem (thus generalizing Kubo's linear reaction theory to a quantum nonlinear stochastic response theory). Third, we establish general relations linking quantum response properties of the system in question to averages of operator products ordered in a way different from time normal. This extends PST to a much wider assemblage of operator products than are usually considered in phase-space approaches. In all cases, our approach yields a very simple and straightforward way of deriving stochastic equations in phase space.
Hénon-Heiles interaction for hydrogen atom in phase space
NASA Astrophysics Data System (ADS)
da Cruz Filho, J. S.; Amorim, R. G. G.; Ulhoa, S. C.; Khanna, F. C.; Santana, A. E.; Vianna, J. D. M.
2016-03-01
Using elements of symmetry, as gauge invariance, several aspects of a Schrödinger equation represented in phase space are introduced and analyzed under physical basis. The hydrogen atom is explored in the same context. Then we add a Hénon-Heiles potential to the hydrogen atom in order to explore chaotic features.
Phase Space Approach for S2 arrow S0 internal conversion in the benzene molecule.
NASA Astrophysics Data System (ADS)
Kallush, Shimshon; Segev, Bilha; Sergeev, Alexei; Heller, Eric J.
2000-06-01
The theoretical problem of finding propensity rules for the partition of energy between competing vibrations in a radiationless vibronic relaxation transition, is converted by the phase-space method of [1,2] to the simple mathematical problem of finding a maximum for a simple function under a constraint. The function is the Wigner function of the initial state and the constraint is energy conservation, defining an accepting energy surface in phase space. We apply this phase space method for finding propensity rules for vibronic transitions when the Frack-Condon factors are exponentially small to the classical example of the benzene molecule. We extend the method to forbidden transitions and include in the analysis non-harmonic force-field effects. Using the phase space analysis, we explain the non-classical behavior of the S_2arrow S0 relaxation of the benzene. Given the energy gap, reasonable displacements and recently calculated force fields [3] we show that almost all the energy must go to C-H stretching. Non-harmonic effects increase in this case the transition rate but do not change the partition of energy between the accepting vibrational modes. [1] E.J. Heller and D. Beck, Chem. Phys. Lett. 202, 350 (1993). [2] B. Segev and E.J. Heller, Journal of Chemical Physics, 112, 4004-4013 (2000). [3] A. Miani, E. Cane, P. Palmieri, A. Trombetti,N.C. Handy, J. Chem. Phys., 112, 248-259 (2000).
Phase space and jet definitions in soft-collinear effective theory
Cheung, William Man-Yin; Luke, Michael; Zuberi, Saba
2009-12-01
We discuss consistent power counting for integrating soft and collinear degrees of freedom over arbitrary regions of phase space in the soft-collinear effective theory, and illustrate our results at one-loop with several jet algorithms: JADE, Sterman-Weinberg and k{sub perpendicular}. Consistently applying soft-collinear effective theory power counting in phase space, along with nontrivial zero-bin subtractions, prevents double counting of final states. The resulting phase space integrals over soft and collinear regions are individually ultraviolet divergent, but the phase space ultraviolet divergences cancel in the sum. Whether the soft and collinear contributions are individually infrared safe depends on the jet definition. We show that while this is true at one-loop for JADE and Sterman-Weinberg, the k{sub perpendicular} algorithm does not factorize into individually infrared safe soft and collinear pieces in dimensional regularization. We point out that this statement depends on the ultraviolet regulator, and that in a cutoff scheme the soft functions are infrared safe.
ERIC Educational Resources Information Center
de Silva, Chamelle R.; Chigona, A.; Adendorff, S. A.
2016-01-01
Among its many affordances, the interactive whiteboard (IWB) as a digital space for children's dialogic engagement in the Foundation Phase classroom remains largely under-exploited. This paper emanates from a study which was undertaken in an attempt to understand how teachers acquire knowledge of emerging technologies and how this shapes their…
Quantum de Finetti theorems and mean-field theory from quantum phase space representations
NASA Astrophysics Data System (ADS)
Trimborn, F.; Werner, R. F.; Witthaut, D.
2016-04-01
We introduce the number-conserving quantum phase space description as a versatile tool to address fundamental aspects of quantum many-body systems. Using phase space methods we prove two alternative versions of the quantum de Finetti theorem for finite-dimensional bosonic quantum systems, which states that a reduced density matrix of a many-body quantum state can be approximated by a convex combination of product states where the error is proportional to the inverse particle number. This theorem provides a formal justification for the mean-field description of many-body quantum systems, as it shows that quantum correlations can be neglected for the calculation of few-body observables when the particle number is large. Furthermore we discuss methods to derive the exact evolution equations for quantum phase space distribution functions as well as upper and lower bounds for the ground state energy. As an important example, we consider the Bose-Hubbard model and show that the mean-field dynamics is given by a classical phase space flow equivalent to the discrete Gross-Pitaevskii equation.
On the nonclassical character of the phase-space representations of quantum mechanics
NASA Astrophysics Data System (ADS)
Guz, W.
1985-02-01
The quasiclassical representations of quantum theory, generalizing the concept of a phase-space representation of quantum mechanics, are studied with particular emphasis on some questions connected with the Jordan structure of the classical and quantum algebras of observables. A generalized version of the theorem of Gleason, Kahane, and Zelazko is used to establish some nonclassical features of these representations.
Phase-space spinor amplitudes for spin-1/2 systems
NASA Astrophysics Data System (ADS)
Watson, P.; Bracken, A. J.
2011-04-01
The concept of phase-space amplitudes for systems with continuous degrees of freedom is generalized to finite-dimensional spin systems. Complex amplitudes are obtained on both a sphere and a finite lattice, in each case enabling a more fundamental description of pure spin states than that previously given by Wigner functions. In each case the Wigner function can be expressed as the star product of the amplitude and its conjugate, so providing a generalized Born interpretation of amplitudes that emphasizes their more fundamental status. The ordinary product of the amplitude and its conjugate produces a (generalized) spin Husimi function. The case of spin-(1)/(2) is treated in detail, and it is shown that phase-space amplitudes on the sphere transform correctly as spinors under rotations, despite their expression in terms of spherical harmonics. Spin amplitudes on a lattice are also found to transform as spinors. Applications are given to the phase space description of state superposition, and to the evolution in phase space of the state of a spin-(1)/(2) magnetic dipole in a time-dependent magnetic field.
Phase-space analysis of convection in a /sup 3/He - superfluid /sup 4/He solution
Haucke, H.; Maeno, Y.
1982-01-01
Observations have been made on thermal convection below 1K in a dilute solution of /sup 3/He in superfluid /sup 4/He contained in a cylindrical cell of aspect ratio GAMMA = 1.20. Complicated oscillatory phenomena were observed with a high degree of reproducibility using two temperature sensors. Phase-space analysis suggests a description in terms of strange-attractor dynamics.
Numerical method for estimating the size of chaotic regions of phase space
Henyey, F.S.; Pomphrey, N.
1987-10-01
A numerical method for estimating irregular volumes of phase space is derived. The estimate weights the irregular area on a surface of section with the average return time to the section. We illustrate the method by application to the stadium and oval billiard systems and also apply the method to the continuous Henon-Heiles system. 15 refs., 10 figs. (LSP)
Not Available
1991-06-07
A new class of X-band phase shifters using the distributed Josephson inductance (DJI) effect were delivered to NRL for the HTS Space Experiment project. Phase shifts were observed above 77 K, and large phase shifts were observed at 65 K and below. This narrow-band device was developed as a first step to a broadband device. A total of 40 HTS SQUIDs were successfully integrated into a monolithic circuit. Measurement of the temperature dependance of the Q of a resonator in June 1990 and in February 1991 showed no significant change due to aging. A total of seven X-band phase shifters were fabricated, and five were delivered to Naval Research Laboratory. The HTS phase shifter consists of a low loss YBa2Cu3O7 microstrip resonator with 40 SQUID devices monolithically imbedded into the transmission line. This narrow-band device was developed as a first step to a broadband device.
Phased array components for the High Temperature Superconducting Space Experiment (HTSSE)
NASA Astrophysics Data System (ADS)
1991-06-01
A new class of X-band phase shifters using the distributed Josephson inductance (DJI) effect were delivered to NRL for the HTS Space Experiment project. Phase shifts were observed above 77 K, and large phase shifts were observed at 65 K and below. This narrow-band device was developed as a first step to a broadband device. A total of 40 HTS SQUIDs were successfully integrated into a monolithic circuit. Measurement of the temperature dependence of the Q of a resonator in June 1990 and in February 1991 showed no significant change due to aging. A total of seven X-band phase shifters were fabricated, and five were delivered to Naval Research Laboratory. The HTS phase shifter consists of a low loss YBa2Cu3O7 microstrip resonator with 40 SQUID devices monolithically imbedded into the transmission line. This narrow-band device was developed as a first step to a broadband device.
Decryption with incomplete cyphertext and multiple-information encryption in phase space.
Xu, Xiaobin; Wu, Quanying; Liu, Jun; Situ, Guohai
2016-01-25
Recently, we have demonstrated that information encryption in phase space offers security enhancement over the traditional encryption schemes operating in real space. However, there is also an important issue with this technique: increasing the cost for data transmitting and storage. To address this issue, here we investigate the problem of decryption using incomplete cyphertext. We show that the analytic solution under the traditional framework set the lower limit of decryption performance. More importantly, we demonstrate that one just needs a small amount of cyphertext to recover the plaintext signal faithfully using compressive sensing, meaning that the amount of data that needs to transmit and store can be significantly reduced. This leads to multiple information encryption so that we can use the system bandwidth more effectively. We also provide an optical experimental result to demonstrate the plaintext recovered in phase space. PMID:26832552
Simulated response of top-hat electrostatic analysers - importance of phase-space resolution
NASA Astrophysics Data System (ADS)
De Marco, Rossana; Bruno, Roberto; D'Amicis, Raffaella; Federica Marcucci, Maria; Servidio, Sergio; Valentini, Francesco
2016-04-01
We use a numerical code able to reproduce the angular/energy response of a typical electrostatic analyzer of top-hat type starting from velocity distribution functions (VDFs) generated by numerical imulations.The simulations are based on the Hybrid Vlasov-Maxwell (HVM) numerical algorithm which integrates the Vlasov equation for the ion distribution function in multi-dimensional geometry in phase space, while the electrons are treated as a fluid. Virtual satellites launched through the simulation box measure the particle VDFs. Such VDFs are interpolated into a spacecraft reference frame and moved from the simulation Cartesian grid to energy-angular coordinates to mimic the response of a real electrostatic sensor in the solar wind and in the magnetosheath for different conditions. We discuss the results of this study with respect to the importance of phase-space resolution for a space plasma experiment meant to investigate kinetic plasma regime.
Real-time transverse-emittance and phase-space monitor
NASA Astrophysics Data System (ADS)
Song, J.; Piot, P.; Legg, R.; Kehne, D.; Li, R.; Feldl, E.; Jordan, K.; Denard, J.-C.; Krafft, G. A.; Neil, G. R.; Bohn, C. L.
1998-02-01
A real-time multislit [1]transverse-emittance monitor has been developed for diagnosing the space-charge-dominated beam in the 10 MeV injection line of the FEL at Thomas Jefferson National Accelerator Facility (formerly CEBAF). It gives emittance, Twiss parameters, and phase-space contours (without any symmetry assumptions) at the update rate of 1 Hz. It reduces measurement noise in real-time, and incorporates a special algorithm for constructing the phase-space matrix, which yields more accurate results by sweeping the beam across the slits. In this paper we will discuss issues relevant to the software design and implementation. Experimental results obtained from a 250 keV photocathode gun will also be presented and compared with other methods and with PARMELA simulations.
The effect of phase angle and wing spacing on tandem flapping wings
NASA Astrophysics Data System (ADS)
Broering, Timothy M.; Lian, Yong-Sheng
2012-12-01
In a tandem wing configuration, the hindwing often operates in the wake of the forewing and, hence, its performance is affected by the vortices shed by the forewing. Changes in the phase angle between the flapping motions of the fore and the hind wings, as well as the spacing between them, can affect the resulting vortex/wing and vortex/vortex interactions. This study uses 2D numerical simulations to investigate how these changes affect the leading dege vortexes (LEV) generated by the hindwing and the resulting effect on the lift and thrust coefficients as well as the efficiencies. The tandem wing configuration was simulated using an incompressible Navier-Stokes solver at a chord-based Reynolds number of 5 000. A harmonic single frequency sinusoidal oscillation consisting of a combined pitch and plunge motion was used for the flapping wing kinematics at a Strouhal number of 0.3. Four different spacings ranging from 0.1 chords to 1 chord were tested at three different phase angles, 0°, 90° and 180°. It was found that changes in the spacing and phase angle affected the timing of the interaction between the vortex shed from the forewing and the hindwing. Such an interaction affects the LEV formation on the hindwing and results in changes in aerodynamic force production and efficiencies of the hindwing. It is also observed that changing the phase angle has a similar effect as changing the spacing. The results further show that at different spacings the peak force generation occurs at different phase angles, as do the peak efficiencies.
Optical authentication based on moiré effect of nonlinear gratings in phase space
NASA Astrophysics Data System (ADS)
Liao, Meihua; He, Wenqi; Wu, Jiachen; Lu, Dajiang; Liu, Xiaoli; Peng, Xiang
2015-12-01
An optical authentication scheme based on the moiré effect of nonlinear gratings in phase space is proposed. According to the phase function relationship of the moiré effect in phase space, an arbitrary authentication image can be encoded into two nonlinear gratings which serve as the authentication lock (AL) and the authentication key (AK). The AL is stored in the authentication system while the AK is assigned to the authorized user. The authentication procedure can be performed using an optoelectronic approach, while the design process is accomplished by a digital approach. Furthermore, this optical authentication scheme can be extended for multiple users with different security levels. The proposed scheme can not only verify the legality of a user identity, but can also discriminate and control the security levels of legal users. Theoretical analysis and simulation experiments are provided to verify the feasibility and effectiveness of the proposed scheme.
NASA Technical Reports Server (NTRS)
Romanofsky, Robert R.
2007-01-01
Though there are a few examples of scanning phased array antennas that have flown successfully in space, the quest for low-cost, high-efficiency, large aperture microwave phased arrays continues. Fixed and mobile applications that may be part of a heterogeneous exploration communication architecture will benefit from the agile (rapid) beam steering and graceful degradation afforded by phased array antennas. The reflectarray promises greater efficiency and economy compared to directly-radiating varieties. Implementing a practical scanning version has proven elusive. The ferroelectric reflectarray, under development and described herein, involves phase shifters based on coupled microstrip patterned on Ba(x)Sr(1-x)TiO3 films, that were laser ablated onto LaAlO3 substrates. These devices outperform their semiconductor counterparts from X- through and K-band frequencies. There are special issues associated with the implementation of a scanning reflectarray antenna, especially one realized with thin film ferroelectric phase shifters. This paper will discuss these issues which include: relevance of phase shifter loss; modulo 2(pi) effects and phase shifter transient effects on bit error rate; scattering from the ground plane; presentation of a novel hybrid ferroelectric-semiconductor phase shifter; and the effect of mild radiation exposure on phase shifter performance.
Mixed semiclassical-classical propagators for the Wigner phase space representation.
Koda, Shin-Ichi
2016-04-21
We formulate mixed semiclassical-classical (SC-Cl) propagators by adding a further approximation to the phase-space SC propagators, which have been formulated in our previous paper [S. Koda, J. Chem. Phys. 143, 244110 (2015)]. We first show that the stationary phase approximation over the operation of the phase-space van Vleck propagator on initial distribution functions results in the classical mechanical time propagation. Then, after dividing the degrees of freedom (DOFs) of the total system into the semiclassical DOFs and the classical DOFs, the SC-Cl van Vleck propagator and the SC-Cl Herman-Kluk (HK) propagator are derived by performing the stationary phase approximation only with respect to the classical DOFs. These SC-Cl propagators are naturally decomposed to products of the phase-space SC propagators and the classical mechanical propagators when the system does not have any interaction between the semiclassical and the classical DOFs. In addition, we also numerically compare the original phase-space HK (full HK) propagator and the SC-Cl HK propagator in terms of accuracy and efficiency to find that the accuracy of the SC-Cl HK propagator can be comparable to that of the full HK propagator although the latter is more accurate than the former in general. On the other hand, we confirm that the convergence speed of the SC-Cl HK propagator is faster than that of the full HK propagator. The present numerical tests indicate that the SC-Cl HK propagator can be more accurate than the full HK propagator when they use a same and finite number of classical trajectories due to the balance of the accuracy and the efficiency. PMID:27389210
Mixed semiclassical-classical propagators for the Wigner phase space representation
NASA Astrophysics Data System (ADS)
Koda, Shin-ichi
2016-04-01
We formulate mixed semiclassical-classical (SC-Cl) propagators by adding a further approximation to the phase-space SC propagators, which have been formulated in our previous paper [S. Koda, J. Chem. Phys. 143, 244110 (2015)]. We first show that the stationary phase approximation over the operation of the phase-space van Vleck propagator on initial distribution functions results in the classical mechanical time propagation. Then, after dividing the degrees of freedom (DOFs) of the total system into the semiclassical DOFs and the classical DOFs, the SC-Cl van Vleck propagator and the SC-Cl Herman-Kluk (HK) propagator are derived by performing the stationary phase approximation only with respect to the classical DOFs. These SC-Cl propagators are naturally decomposed to products of the phase-space SC propagators and the classical mechanical propagators when the system does not have any interaction between the semiclassical and the classical DOFs. In addition, we also numerically compare the original phase-space HK (full HK) propagator and the SC-Cl HK propagator in terms of accuracy and efficiency to find that the accuracy of the SC-Cl HK propagator can be comparable to that of the full HK propagator although the latter is more accurate than the former in general. On the other hand, we confirm that the convergence speed of the SC-Cl HK propagator is faster than that of the full HK propagator. The present numerical tests indicate that the SC-Cl HK propagator can be more accurate than the full HK propagator when they use a same and finite number of classical trajectories due to the balance of the accuracy and the efficiency.
MMIC linear-phase and digital modulators for deep space spacecraft X-band transponder applications
NASA Technical Reports Server (NTRS)
Mysoor, Narayan R.; Ali, Fazal
1991-01-01
The design concepts, analyses, and development of GaAs monolithic microwave integrated circuit (MMIC) linear-phase and digital modulators for the next generation of space-borne communications systems are summarized. The design approach uses a compact lumped element quadrature hybrid and Metal Semiconductor Field Effect Transistors (MESFET)-varactors to provide low loss and well-controlled phase performance for deep space transponder (DST) applications. The measured results of the MESFET-diode show a capacitance range of 2:1 under reverse bias, and a Q of 38 at 10 GHz. Three cascaded sections of hybrid-coupled reflection phase shifters were modeled and simulations performed to provide an X-band (8415 +/- 50 MHz) DST phase modulator with +/- 2.5 radians of peak phase deviation. The modulator will accommodate downlink signal modulation with composite telemetry and ranging data, with a deviation linearity tolerance of +/- 8 percent and insertion loss of less than 8 +/- 0.5 dB. The MMIC digital modulator is designed to provide greater than 10 Mb/s of bi-phase modulation at X-band.
Gao, Zhong-Ke; Jin, Ning-De; Wang, Wen-Xu; Lai, Ying-Cheng
2010-07-01
The dynamics of two-phase flows have been a challenging problem in nonlinear dynamics and fluid mechanics. We propose a method to characterize and distinguish patterns from inclined water-oil flow experiments based on the concept of network motifs that have found great usage in network science and systems biology. In particular, we construct from measured time series phase-space complex networks and then calculate the distribution of a set of distinct network motifs. To gain insight, we first test the approach using time series from classical chaotic systems and find a universal feature: motif distributions from different chaotic systems are generally highly heterogeneous. Our main finding is that the distributions from experimental two-phase flows tend to be heterogeneous as well, suggesting the underlying chaotic nature of the flow patterns. Calculation of the maximal Lyapunov exponent provides further support for this. Motif distributions can thus be a feasible tool to understand the dynamics of realistic two-phase flow patterns. PMID:20866710
GPS-Like Phasing Control of the Space Solar Power System Transmission Array
NASA Technical Reports Server (NTRS)
Psiaki, Mark L.
2003-01-01
The problem of phasing of the Space Solar Power System's transmission array has been addressed by developing a GPS-like radio navigation system. The goal of this system is to provide power transmission phasing control for each node of the array that causes the power signals to add constructively at the ground reception station. The phasing control system operates in a distributed manner, which makes it practical to implement. A leader node and two radio navigation beacons are used to control the power transmission phasing of multiple follower nodes. The necessary one-way communications to the follower nodes are implemented using the RF beacon signals. The phasing control system uses differential carrier phase relative navigation/timing techniques. A special feature of the system is an integer ambiguity resolution procedure that periodically resolves carrier phase cycle count ambiguities via encoding of pseudo-random number codes on the power transmission signals. The system is capable of achieving phasing accuracies on the order of 3 mm down to 0.4 mm depending on whether the radio navigation beacons operate in the L or C bands.
Phase space analysis and classification of sonar echoes in shallow-water channels
NASA Astrophysics Data System (ADS)
Okopal, Greg
A primary objective of active sonar systems is to detect, locate, and classify objects, such as mines, ships, and biologics, based on their sonar backscatter. A shallow-water ocean channel is a challenging environment in which to classify sonar echoes because interactions of the sonar signal with the ocean surface and bottom induce frequency-dependent changes (especially dispersion and damping) in the signal as it propagates, the effects of which typically grow with range. Accordingly, the observed signal depends not only on the initial target backscatter, but also the propagation channel and how far the signal has propagated. These propagation effects can increase the variability of observed target echoes and degrade classification performance. Furthermore, uncertainty of the exact propagation channel and random variations within a channel cause classification features extracted from the received sonar echo to behave as random variables. With the goal of improving sonar signal classification in shallow-water environments, this work develops a phase space framework for studying sound propagation in channels with dispersion and damping. This approach leads to new moment features for classification that are invariant to dispersion and damping, the utility of which is demonstrated via simulation. In addition, the accuracy of a previously developed phase space approximation method for range-independent pulse propagation is analyzed and shown to be greater than the accuracy of the standard stationary phase approximation for both large and small times/distances. The phase space approximation is also extended to range dependent propagation. Finally, the phase space approximation is used to investigate the random nature of moment features for classification by calculating the moments of the moment features under uncertain and random channel assumptions. These moments of the moment features are used to estimate probability distribution functions for the moment features, and
Zero-g experiments with a He II active phase separator for space application
NASA Technical Reports Server (NTRS)
Denner, H. D.; Klipping, G.; Lueders, K.; Ruppert, U.; Stahnke, F.; Szuecs, Z.; Elleman, D.; Petrac, D.
1984-01-01
An active phase separator (APS) for temperature control of He II space cooling systems was tested in a zero-g environment during a series of parabolic flights on a NASA KC 135 aircraft. The APS provides for liquid-gas separation and features an annular gap, a downstream heat exchanger and an upstream ball closure. The apparatus was operated during acceleration and floating and in two different heat load situations. The tests confirmed that adequate mass flow rates could be maintained using a vacuum pump to simulate space vacuum and that residual liquid could be evaporated from the heat exchanger after closing a ball valve to seal off flows.
Homoclinic orbits around spinning black holes. II. The phase space portrait
Perez-Giz, Gabe; Levin, Janna
2009-06-15
In paper I in this series, we found exact expressions for the equatorial homoclinic orbits: the separatrix between bound and plunging, whirling and not whirling motion. As a companion to that physical space study, in this paper we paint a phase space portrait of the homoclinic orbits that includes exact expressions for the actions and fundamental frequencies. Additionally, we develop a reduced Hamiltonian description of Kerr motion that allows us to track groups of trajectories with a single global clock. This facilitates a variational analysis, whose stability exponents and eigenvectors could potentially be useful for future studies of families of black hole orbits and their associated gravitational waveforms.
Advanced ceramic fabric body mounted radiator for Space Station Freedom Phase O design
Webb, B.J.; Antoniak, Z.I.; Pauley, K.A.
1990-06-01
A body mounted radiator concept constructed of advanced ceramic fabric materials for use with the Phase 0 design of Space Station Freedom is described. The radiator is expected to weigh between 1.4 and 3.5 kg/m{sup 2} of single sided radiating surface, use ammonia working fluid, be highly deployable, and exhibit good reliability characteristics. This compares well with the 11.8 kg/m{sup 2} for two sided radiators proposed for the current space station design.
The Phase-Space Structure of Cold Dark Matter in the Universe
NASA Astrophysics Data System (ADS)
Shandarin, Sergei
2015-01-01
A novel method allowing to compute density, velocity and other fields in cosmological N-body simulations with unprecedentedly high spatial resolution is described. It is based on the tessellation of the three-dimensional manifold representing cold dark matter in six-dimensional phase space. The density, velocity and other fields are computed by projecting the tessellation on configuration space. The application of this technique to cosmological N-body simulations in ΛCDM cosmology reveals a far more elaborate cosmic web then dot plots or self-adaptive SPH. In addition, this method allows to uniquely define physical voids and identify and study the caustic surfaces directly.
NASA Technical Reports Server (NTRS)
Cadogan, Dave; Lingo, Bob
1996-01-01
In July of 1996, ILC Dover was awarded Phase 1 of a contract for NASA to develop a prototype Power Assisted Space Suit glove to enhance the performance of astronauts during Extra-Vehicular Activity (EVA). This report summarizes the work performed to date on Phase 1, and details the work to be conducted on Phase 2 of the program. Phase 1 of the program consisted of research and review of related technical sources, concept brainstorming, baseline design development, modeling and analysis, component mock-up testing, and test data analysis. ILC worked in conjunction with the University of Maryland's Space Systems Laboratory (SSL) to develop the power assisted glove. Phase 2 activities will focus on the design maturation and the manufacture of a working prototype system. The prototype will be tested and evaluated in conjunction with existing space suit glove technology to determine the performance enhancement anticipated with the implementation of the power assisted joint technology in space suit gloves.
Akkelin, S.V.; Sinyukov, Yu.M.
2004-12-01
A method allowing analysis of the overpopulation of phase space in heavy ion collisions in a model-independent way is proposed within the hydrodynamic approach. It makes it possible to extract a chemical potential of thermal pions at freeze-out, irrespective of the form of freeze-out (isothermal) hypersurface in Minkowski space and transverse flows on it. The contributions of resonance (with masses up to 2 GeV) decays to spectra, interferometry volumes, and phase-space densities are calculated and discussed in detail. The estimates of average phase-space densities and chemical potentials of thermal pions are obtained for SPS and RHIC energies. They demonstrate that multibosonic phenomena at those energies might be considered as a correction factor rather than as a significant physical effect. The analysis of the evolution of the pion average phase-space density in chemically frozen hadron systems shows that it is almost constant or slightly increases with time while the particle density and phase-space density at each space point decreases rapidly during the system's expansion. We found that, unlike the particle density, the average phase-space density has no direct link to the freeze-out criterion and final thermodynamic parameters, being connected rather to the initial phase-space density of hadronic matter formed in relativistic nucleus-nucleus collisions.
Movie of phase separation during physics of colloids in space experiment
NASA Technical Reports Server (NTRS)
2002-01-01
Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area in the video is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.
Phase separation during the Experiment on Physics of Colloids in Space
NASA Technical Reports Server (NTRS)
2003-01-01
Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.
ERIC Educational Resources Information Center
Nicolaides, Cleanthes A.; Constantoudis, Vasilios
2009-01-01
In Planck's model of the harmonic oscillator (HO) a century ago, both the energy and the phase space were quantized according to epsilon[subscript n] = nhv, n = 0, 1, 2..., and [double integral]dp[subscript x] dx = h. By referring to just these two relations, we show how the adoption of "cycle-averaged phase-space states" (CAPSSs) leads to the…
High-Throughput Thin Film Approach for Screening of Temperature-Pressure-Composition Phase Space
Zakutayev, A.; Subramaniyan, A.; Caskey, C. M.; Ndione, P. F.; Richards, R. M.; O'Hayre, R.; Ginley, D. S.
2013-01-01
Many solar energy technologies, for example CIGS and CdTe photovoltaics, utilize materials in thin film form. The equilibrium phase diagrams for these and other more novel solar energy materials are not known or are irrelevant because of the non-equilibrium character of the thin film growth processes. We demonstrate a high-throughput thin film approach for screening of temperature-pressure-composition phase diagrams and phase spaces. The examples in focus are novel solar absorbers Cu-N, Cu-O and p-type transparent conductors in the Cr2O3-MnO system. The composition axis of the Cr2O3-MnO phase diagram was screened using a composition spread method. The temperature axis of the Mn-O phase diagram was screened using a temperature spread method. The pressure axes of the Cu-N and Cu-O phase diagrams were screened using rate spread method with the aid of non-equilibrium growth phenomena. Overall these three methods constitute an approach to high-throughput screening of inorganic thin film phase diagrams. This research is supported by U.S. Department of Energy as a part of two NextGen Sunshot projects and an Energy Frontier Research Center.
Exploring the phase space of multiple states in highly turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
van der Veen, Roeland C. A.; Huisman, Sander G.; Dung, On-Yu; Tang, Ho L.; Sun, Chao; Lohse, Detlef
2016-06-01
We investigate the existence of multiple turbulent states in highly turbulent Taylor-Couette flow in the range of Ta =1011 to 9 ×1012 by measuring the global torques and the local velocities while probing the phase space spanned by the rotation rates of the inner and outer cylinders. The multiple states are found to be very robust and are expected to persist beyond Ta =1013 . The rotation ratio is the parameter that most strongly controls the transitions between the flow states; the transitional values only weakly depend on the Taylor number. However, complex paths in the phase space are necessary to unlock the full region of multiple states. By mapping the flow structures for various rotation ratios in a Taylor-Couette setup with an equal radius ratio but a larger aspect ratio than before, multiple states are again observed. Here they are characterized by even richer roll structure phenomena, including an antisymmetrical roll state.
Design of Transversal Phase Space Meter for Atomic Hydrogen Beam Source
NASA Astrophysics Data System (ADS)
Belov, A. S.
2016-02-01
For optimization of polarized atomic beam sources apparatus it is important to have detailed information about characteristics of sources of hydrogen atoms, especially, taking into account present intensity limitations of polarized atomic beam sources. Usually, longitudinal velocity distribution of hydrogen atoms produced by RF dissociator is measured while transversal phase space of unpolarized atomic hydrogen beams was not measured up to now. In this work we report and discuss a design of transversal phase space meter for pulsed atomic hydrogen beam source. The meter design is based on “two slits” method which is well known from ion beam technique. Specific feature of the meter are movable sensitive detector of hydrogen atoms and molecules.
NASA Astrophysics Data System (ADS)
Khosravi, Nima; Sepangi, Hamid Reza; Vakili, Babak
2010-05-01
We employ the familiar canonical quantization procedure in a given cosmological setting to argue that it is equivalent to and results in the same physical picture if one considers the deformation of the phase-space instead. To show this we use a probabilistic evolutionary process to make the solutions of these different approaches comparable. Specific model theories are used to show that the independent solutions of the resulting Wheeler-DeWitt equation are equivalent to solutions of the deformation method with different signs for the deformation parameter. We also argued that since the Wheeler-DeWitt equation is a direct consequence of diffeomorphism invariance, this equivalence is only true provided that the deformation of phase-space does not break such an invariance.
Statistics of the island-around-island hierarchy in Hamiltonian phase space.
Alus, Or; Fishman, Shmuel; Meiss, James D
2014-12-01
The phase space of a typical Hamiltonian system contains both chaotic and regular orbits, mixed in a complex, fractal pattern. One oft-studied phenomenon is the algebraic decay of correlations and recurrence time distributions. For area-preserving maps, this has been attributed to the stickiness of boundary circles, which separate chaotic and regular components. Though such dynamics has been extensively studied, a full understanding depends on many fine details that typically are beyond experimental and numerical resolution. This calls for a statistical approach, the subject of the present work. We calculate the statistics of the boundary circle winding numbers, contrasting the distribution of the elements of their continued fractions to that for uniformly selected irrationals. Since phase space transport is of great interest for dynamics, we compute the distributions of fluxes through island chains. Analytical fits show that the "level" and "class" distributions are distinct, and evidence for their universality is given. PMID:25615180
New Thermodynamical Force in Plasma Phase Space that Controls Turbulence and Turbulent Transport
Itoh, Sanae-I.; Itoh, Kimitaka
2012-01-01
Physics of turbulence and turbulent transport has been developed on the central dogma that spatial gradients constitute the controlling parameters, such as Reynolds number and Rayleigh number. Recent experiments with the nonequilibrium plasmas in magnetic confinement devices, however, have shown that the turbulence and transport change much faster than global parameters, after an abrupt change of heating power. Here we propose a theory of turbulence in inhomogeneous magnetized plasmas, showing that the heating power directly influences the turbulence. New mechanism, that an external source couples with plasma fluctuations in phase space so as to affect turbulence, is investigated. A new thermodynamical force in phase-space, i.e., the derivative of heating power by plasma pressure, plays the role of new control parameter, in addition to spatial gradients. Following the change of turbulence, turbulent transport is modified accordingly. The condition under which this new effect can be observed is also evaluated. PMID:23155481
Explosive synchronization as a process of explosive percolation in dynamical phase space
Zhang, Xiyun; Zou, Yong; Boccaletti, S.; Liu, Zonghua
2014-01-01
Explosive synchronization and explosive percolation are currently two independent phenomena occurring in complex networks, where the former takes place in dynamical phase space while the latter in configuration space. It has been revealed that the mechanism of EP can be explained by the Achlioptas process, where the formation of a giant component is controlled by a suppressive rule. We here introduce an equivalent suppressive rule for ES. Before the critical point of ES, the suppressive rule induces the presence of multiple, small sized, synchronized clusters, while inducing the abrupt formation of a giant cluster of synchronized oscillators at the critical coupling strength. We also show how the explosive character of ES degrades into a second-order phase transition when the suppressive rule is broken. These results suggest that our suppressive rule can be considered as a dynamical counterpart of the Achlioptas process, indicating that ES and EP can be unified into a same framework. PMID:24903808
High order surface aberration contributions from phase space analysis of differential rays.
Chen, Bo; Herkommer, Alois M
2016-03-21
Phase space methods are very popular for illumination systems or paraxial system analysis. In this paper it will be shown that it is also a promising tool to visualize and quantify surface aberration contributions, including all orders. The method is based on the calculation and propagation of a differential ray pair. In order to validate the method we compare to Aldis calculus, an exact method to determine high order aberrations in rotational symmetric systems. A triplet lens is used as an example to visualize the results. The analysis indicates that the phase space method is a very good approximation to Aldis calculus and moreover it is not limited to any symmetry assumptions. PMID:27136789
New Thermodynamical Force in Plasma Phase Space that Controls Turbulence and Turbulent Transport
NASA Astrophysics Data System (ADS)
Itoh, Sanae-I.; Itoh, Kimitaka
2012-11-01
Physics of turbulence and turbulent transport has been developed on the central dogma that spatial gradients constitute the controlling parameters, such as Reynolds number and Rayleigh number. Recent experiments with the nonequilibrium plasmas in magnetic confinement devices, however, have shown that the turbulence and transport change much faster than global parameters, after an abrupt change of heating power. Here we propose a theory of turbulence in inhomogeneous magnetized plasmas, showing that the heating power directly influences the turbulence. New mechanism, that an external source couples with plasma fluctuations in phase space so as to affect turbulence, is investigated. A new thermodynamical force in phase-space, i.e., the derivative of heating power by plasma pressure, plays the role of new control parameter, in addition to spatial gradients. Following the change of turbulence, turbulent transport is modified accordingly. The condition under which this new effect can be observed is also evaluated.
The Approach for Action Recognition Based on the Reconstructed Phase Spaces
Tu, Hong-bin; Xia, Li-min
2014-01-01
This paper presents a novel method of human action recognition, which is based on the reconstructed phase space. Firstly, the human body is divided into 15 key points, whose trajectory represents the human body behavior, and the modified particle filter is used to track these key points for self-occlusion. Secondly, we reconstruct the phase spaces for extracting more useful information from human action trajectories. Finally, we apply the semisupervised probability model and Bayes classified method for classification. Experiments are performed on the Weizmann, KTH, UCF sports, and our action dataset to test and evaluate the proposed method. The compare experiment results showed that the proposed method can achieve was more effective than compare methods. PMID:25436224
Phase-retrieval analysis of pre- and post-repair Hubble Space Telescope images.
Krist, J E; Burrows, C J
1995-08-01
Phase-retrieval measurements of point-spread functions from the pre- and post-repair Hubble Space Telescope are presented. The primary goal was to determine the aberrations present in the second wide-field and planetary camera (WFPC2) to align and validate its corrective optics. With both parametric model-fitting techniques and iterative (Gerchberg-Saxton) methods, accurate measurements have been obtained of the WFPC2 and Hubble Space Telescope optics, including improved maps of the zonal errors in the mirrors. Additional phase-retrieval results were obtained for the aberrated, prerepair cameras and the corrected faint-object camera. The information has been used to improve models produced by point-spread-function simulation programs. On the basis of the measurements a conic constant for the primary mirror of κ = -1.0144 has been derived. PMID:21052338
Longitudinal phase-space coating of beam in a storage ring
NASA Astrophysics Data System (ADS)
Bhat, C. M.
2014-06-01
In this Letter, I report on a novel scheme for beam stacking without any beam emittance dilution using a barrier rf system in synchrotrons. The general principle of the scheme called longitudinal phase-space coating, validation of the concept via multi-particle beam dynamics simulations applied to the Fermilab Recycler, and its experimental demonstration are presented. In addition, it has been shown and illustrated that the rf gymnastics involved in this scheme can be used in measuring the incoherent synchrotron tune spectrum of the beam in barrier buckets and in producing a clean hollow beam in longitudinal phase space. The method of beam stacking in synchrotrons presented here is the first of its kind.
Berg, J. S.
2015-05-03
The International Muon Ionization Cooling Experiment (MICE) is an experiment to demonstrate ionization cooling of a muon beam in a beamline that shares characteristics with one that might be used for a muon collider or neutrino factory. I describe a way to quantify cooling performance by examining the phase space density of muons, and determining how much that density increases. This contrasts with the more common methods that rely on the covariance matrix and compute emittances from that. I discuss why a direct measure of phase space density might be preferable to a covariance matrix method. I apply this technique to an early proposal for the MICE final step beamline. I discuss how matching impacts the measured performance.
Workshop on Two-Phase Fluid Behavior in a Space Environment
NASA Technical Reports Server (NTRS)
Swanson, Theodore D. (Editor); Juhasz, AL (Editor); Long, W. Russ (Editor); Ottenstein, Laura (Editor)
1989-01-01
The Workshop was successful in achieving its main objective of identifying a large number of technical issues relating to the design of two-phase systems for space applications. The principal concern expressed was the need for verified analytical tools that will allow an engineer to confidently design a system to a known degree of accuracy. New and improved materials, for such applications as thermal storage and as heat transfer fluids, were also identified as major needs. In addition to these research efforts, a number of specific hardware needs were identified which will require development. These include heat pumps, low weight radiators, advanced heat pipes, stability enhancement devices, high heat flux evaporators, and liquid/vapor separators. Also identified was the need for a centralized source of reliable, up-to-date information on two-phase flow in a space environment.
Anomalous resistivity of current-driven isothermal plasmas due to phase space structuring
Buechner, Joerg; Elkina, Nina
2006-08-15
The anomalous electric resistivity of collisionless plasmas is an important issue in the physics of hot plasmas, e.g., in the context of auroral particle acceleration and of reconnection in the solar corona. The linear stability theory of isothermal current driven space plasmas predicts an ion-acoustic instability if the relative drift velocity of the current carrying particles exceeds a certain threshold, which, generally, depends on the plasma parameters. The spectrum of waves, excited by a marginal instability, is very narrow. Hence, the wave power at saturation and the corresponding electric resistivity due to wave-particle interaction cannot be obtained by means of a quasilinear, weak turbulence approach and the nonlinear single mode theory provides too small saturation amplitudes. To solve the nonlinear problem a newly developed unsplit conservative Eulerian Vlasov code is applied to simulate a strongly magnetized current driven plasma, which can be considered in 1D1V (one spatial, one velocity space direction). Instead of periodic boundary conditions, usually used as they are simpler to treat, open boundaries are implemented which allow to maintain a constant current flow. Simulated is a typical almost isothermal (T{sub e}=2T{sub i}) hot ({kappa}T{sub i}=1 keV) space plasma for the real mass ratio m{sub i}/m{sub e}=1836. The initial spontaneous instability is followed by a three-stage nonlinear evolution: First electron trapping leads to the formation of electron phase space holes. Due to a steepening of the leading edges of the potential wells the electron phase space holes gradually become asymmetric, they grow in size and deepen. The phase space holes accelerate until they move much faster than the initial ion-acoustic waves. The interaction of the current carriers with the asymmetric potential wells and causes a nonvanishing net momentum transfer between the particles and the self-generated electric field. After a few ion plasma periods ion trapping
The local dark matter phase-space density and impact on WIMP direct detection
Catena, Riccardo; Ullio, Piero E-mail: ullio@sissa.it
2012-05-01
We present a new determination of the local dark matter phase-space density. This result is obtained implementing, in the limit of isotropic velocity distribution and spherical symmetry, Eddington's inversion formula, which links univocally the dark matter distribution function to the density profile, and applying, within a Bayesian framework, a Markov Chain Monte Carlo algorithm to sample mass models for the Milky Way against a broad and variegated sample of dynamical constraints. We consider three possible choices for the dark matter density profile, namely the Einasto, NFW and Burkert profiles, finding that the velocity dispersion, which characterizes the width in the distribution, tends to be larger for the Burkert case, while the escape velocity depends very weakly on the profile, with the mean value we obtain being in very good agreement with estimates from stellar kinematics. The derived dark matter phase-space densities differ significantly — most dramatically in the high velocity tails — from the model usually taken as a reference in dark matter detection studies, a Maxwell-Boltzmann distribution with velocity dispersion fixed in terms of the local circular velocity and with a sharp truncation at a given value of the escape velocity. We discuss the impact of astrophysical uncertainties on dark matter scattering rates and direct detection exclusion limits, considering a few sample cases and showing that the most sensitive ones are those for light dark matter particles and for particles scattering inelastically. As a general trend, regardless of the assumed profile, when adopting a self-consistent phase-space density, we find that rates are larger, and hence exclusion limits stronger, than with the standard Maxwell-Boltzmann approximation. Tools for applying our result on the local dark matter phase-space density to other dark matter candidates or experimental setups are provided.
Quantum simulations in phase-space: from quantum optics to ultra-cold physics
NASA Astrophysics Data System (ADS)
Drummond, Peter D.; Chaturvedi, Subhash
2016-07-01
As a contribution to the international year of light, we give a brief history of quantum optics in phase-space, with new directions including quantum simulations of multipartite Bell violations, opto-mechanics, ultra-cold atomic systems, matter-wave Bell violations, coherent transport and quantum fluctuations in the early Universe. We mostly focus on exact methods using the positive-P representation, and semiclassical truncated Wigner approximations.
Towards high phase space density of alkali atoms by simple optical cooling
NASA Astrophysics Data System (ADS)
Hu, Jiazhong; Vendeiro, Zachary; Chen, Wenlan; Vuletic, Vladan
2016-05-01
We demonstrate a simple optical cooling method, which can cool down the temperature of rubidium 87 to the ground state of the vibrational levels. We only use one far-detuned laser performing both cooling and optical repumping. By tuning the laser frequency, we verify the dependence of the two-body collision loss versus the laser detuning. Combining with the retrap of the atoms in the optical dipole trap, we can make the phase space density approaching to unity.
Generation of a novel phase-space-based cylindrical dose kernel for IMRT optimization
Zhong Hualiang; Chetty, Indrin J.
2012-05-15
Purpose: Improving dose calculation accuracy is crucial in intensity-modulated radiation therapy (IMRT). We have developed a method for generating a phase-space-based dose kernel for IMRT planning of lung cancer patients. Methods: Particle transport in the linear accelerator treatment head of a 21EX, 6 MV photon beam (Varian Medical Systems, Palo Alto, CA) was simulated using the EGSnrc/BEAMnrc code system. The phase space information was recorded under the secondary jaws. Each particle in the phase space file was associated with a beamlet whose index was calculated and saved in the particle's LATCH variable. The DOSXYZnrc code was modified to accumulate the energy deposited by each particle based on its beamlet index. Furthermore, the central axis of each beamlet was calculated from the orientation of all the particles in this beamlet. A cylinder was then defined around the central axis so that only the energy deposited within the cylinder was counted. A look-up table was established for each cylinder during the tallying process. The efficiency and accuracy of the cylindrical beamlet energy deposition approach was evaluated using a treatment plan developed on a simulated lung phantom. Results: Profile and percentage depth doses computed in a water phantom for an open, square field size were within 1.5% of measurements. Dose optimized with the cylindrical dose kernel was found to be within 0.6% of that computed with the nontruncated 3D kernel. The cylindrical truncation reduced optimization time by approximately 80%. Conclusions: A method for generating a phase-space-based dose kernel, using a truncated cylinder for scoring dose, in beamlet-based optimization of lung treatment planning was developed and found to be in good agreement with the standard, nontruncated scoring approach. Compared to previous techniques, our method significantly reduces computational time and memory requirements, which may be useful for Monte-Carlo-based 4D IMRT or IMAT treatment planning.
Communication: phase space approach to laser-driven electronic wavepacket propagation.
Takemoto, Norio; Shimshovitz, Asaf; Tannor, David J
2012-07-01
We propose a phase space method to propagate a quantum wavepacket driven by a strong external field. The method employs the periodic von Neumann basis with biorthogonal exchange recently introduced for the calculation of the energy eigenstates of time-independent quantum systems [A. Shimshovitz and D. J. Tannor, Phys. Rev. Lett. (in press) [e-print arXiv:1201.2299v1
Longitudinal phase space manipulation of an ultrashort electron beam via THz IFEL interaction
Moody, J. T.; Li, R. K.; Musumeci, P.; Scoby, C. M.; To, H.
2012-12-21
A scheme where a laser locked THz source is used to manipulate the longitudinal phase space of an ultrashort electron beam using an IFEL interaction is investigated. The efficiency of THz source based on the pulse front tilt optical rectification scheme is increased by cryogenic cooling to achieve sufficient THz power for compression and synchronization. Start-to-end simulations describing the evolution of the beam from the cathode to the compression point after the undulator are presented.
Qubit phase space: SU(n) coherent-state P representations
NASA Astrophysics Data System (ADS)
Barry, D. W.; Drummond, P. D.
2008-11-01
We introduce a phase-space representation for qubits and spin models. The technique uses an SU(n) coherent-state basis and can equally be used for either static or dynamical simulations. We review previously known definitions and operator identities, and show how these can be used to define an off-diagonal, positive phase-space representation analogous to the positive- P function. As an illustration of the phase-space method, we use the example of the Ising model, which has exact solutions for the finite-temperature canonical ensemble in two dimensions. We show how a canonical ensemble for an Ising model of arbitrary structure can be efficiently simulated using SU(2) or atomic coherent states. The technique utilizes a transformation from a canonical (imaginary-time) weighted simulation to an equivalent unweighted real-time simulation. The results are compared to the exactly soluble two-dimensional case. We note that Ising models in one, two, or three dimensions are potentially achievable experimentally as a lattice gas of ultracold atoms in optical lattices. The technique is not restricted to canonical ensembles or to Ising-like couplings. It is also able to be used for real-time evolution and for systems whose time evolution follows a master equation describing decoherence and coupling to external reservoirs. The case of SU(n) phase space is used to describe n -level systems. In general, the requirement that time evolution be stochastic corresponds to a restriction to Hamiltonians and master equations that are quadratic in the group generators or generalized spin operators.
Magnon Kinetics and Bose-Einstein Condensation Studied in Phase Space
Demidov, V. E.; Dzyapko, O.; Buchmeier, M.; Demokritov, S. O.; Stockhoff, T.; Schmitz, G.; Melkov, G. A.
2008-12-19
Using a novel technique providing simultaneous resolution with respect to the wave vector and frequency of magnons, we observed the formation of a Bose-Einstein condensate documented by the narrowing of the magnon distribution in phase space. Based on the measured width of the distribution we determined the effective correlation length of the condensate, which appears to be anisotropic, reflecting the anisotropy of the magnon dispersion spectrum.
ESPAS, the near-Earth space data infrastructure for e-Science: design and development phase
NASA Astrophysics Data System (ADS)
Hapgood, M.; Belehaki, A.; Zolesi, B.
2012-04-01
Space physics models with good predictive capabilities may be used to forecast accurately the state of the near-Earth space environment and to enable end user communities to mitigate the effects of adverse space weather on humans and technological systems. The results obtained from model runs, and also the validation of their performance accuracy, depend to a large extent on the availability of data from as many as possible regions of the near-Earth geospace. Despite the abundance and variety of related observational data, their exploitation is still challenging as they come from different sensors, in different formats and time resolution, and are provided from various organizations worldwide with different distribution procedures and policies. The primary objective of ESPAS is to provide the e-Infrastructure necessary to support the access to observations, extending from the Earth's atmosphere up to the outer radiation belts, including ionosondes, incoherent scatter radars, magnetometers, GNSS receivers and a large number of space sensors and radars. The development of the ESPAS common interface will allow users to uniformly find, access, and use resources of near-Earth space environment observations from ground-based and space-borne instruments and data from distributed data repositories, based on semantically web services (www.espas-fp7.eu). The first phase that will lead to the release of a first prototype includes the design and development of the data model that will support location of all available data from ground based experiments and satellite missions, available at certain spatial coordinates and time interval. For the first release only the basic data sources will be registered (i.e. Cluster, IMAGE/RPI, DEMETER, DIAS, EISCAT ISRs and SWACI). In a second phase, when all databases and enhanced databases will be registered, the ESPAS infrastructure must be extensively tested through the application of several use cases, designed to serve the needs of the
Defending against Internet worms using a phase space method from chaos theory
NASA Astrophysics Data System (ADS)
Hu, Jing; Gao, Jianbo; Rao, Nageswara S.
2007-04-01
Enterprise networks are facing ever-increasing security threats from Distributed Denial of Service (DDoS) attacks, worms, viruses, intrusions, Trojans, port scans, and network misuses, and thus effective monitoring approaches to quickly detect these activities are greatly needed. In this paper, we employ chaos theory and propose an interesting phase space method to detect Internet worms. An Internet worm is a self-propagating program that automatically replicates itself to vulnerable systems and spreads across the Internet. Most deployed worm-detection systems are signature-based. They look for specific byte sequences (called attack signatures) that are known to appear in the attack traffic. Conventionally, the signatures are manually identified by human experts through careful analysis of the byte sequence from captured attack traffic. We propose to embed the traffic sequence to a high-dimensional phase space using chaos theory. We have observed that the signature sequence of a specific worm will occupy specific regions in the phase space, which may be appropriately called the invariant subspace of the worm. The invariant subspace of the worm separates itself widely from the subspace of the normal traffic. This separation allows us to construct three simple metrics, each of which completely separates 100 normal traffic streams from 200 worm traffic streams, without training in the conventional sense. Therefore, the method is at least as accurate as any existing methods. More importantly, our method is much faster than existing methods, such as based on expectation maximization and hidden Markov models.
NASA Astrophysics Data System (ADS)
Nie, Zhenhua; Hao, Hong; Ma, Hongwei
2013-02-01
In this paper, a parameter based on geometry changes of the reconstructed multidimensional phase space of the measured vibration signals for structural damage identification is proposed. The choice of the proper delay time steps and embedding dimensions for phase space reconstruction of linear systems is discussed. Using the determined delay time and embedding dimensions, an index Changes of Phase Space Topology (CPST) with multiple embedding dimensions is calculated and then used to identify the structural damage. To demonstrate the reliability of the proposed method, vibration test data corresponding to different damage states of a continuous reinforced concrete slab is used to calculate the CPST value for damage identification. The results indicate that except the measurement points at structural supports, the CPST values at all the measurement points on the structure increase with structural damage level irrespective of the damage location, indicating that using a single or a minimum number of measurement points and their CPST value can effectively identify damage existence in the structure. The traditional modal-based indices are also calculated using the same vibration data for comparison. It is found that the proposed method with CPST is the most sensitive to structural damage than any modal-based index. The results demonstrate that the proposed method with CPST value is very effective in identifying damage existence in the structure. Although it cannot quantify the damage, it can be a good candidate for continuous structural health monitoring because it needs only a few sensors to detect damage existence in the entire structure.
Prediction of Indian Summer Monsoon Rainfall by Phase-Space Reconstruction Model
NASA Astrophysics Data System (ADS)
Sharma, A. S.; Krishnamurthy, V.
2015-12-01
The prediction of the Indian summer monsoon rainfall at intraseasonal time scale is investigated in this study. The summer monsoon exhibits intraseasonal oscillations (ISOs) with different periods. The leading ISO, with a period of 45 days, is presumably related to the Madden-Julian Oscillation. The ISOs have large-scale spatial structure and propagate northeastward and northwestward. A prediction model, based on some basic results of nonlinear dynamical systems theory, is constructed to predict the monsoon rainfall. An equivalent phase space of reduced dimension can be reconstructed from a long time-series of a single or a few variables of the dynamical system. In such a phase space, the trajectory of the dynamical system can be examined to search for nearest neighbors. An ensemble of such nearest neighbors and their subsequent evolution are used to construct the prediction model. In some respects, this method is similar to Lorenz's analog method. The reduced phase space is reconstructed by using a limited number of eigenmodes obtained from multi-channel singular spectrum analysis of the rainfall over the monsoon region. For this purpose, the daily gridded rainfall over India for the period 1901-2010 is used. These eigenmodes represent the ISOs and seasonally persistent modes. The prediction of the monsoon rainfall by this model is compared with the retrospective forecasts made by NCEP CFSv2 and other S2S models.
The quantum state vector in phase space and Gabor's windowed Fourier transform
NASA Astrophysics Data System (ADS)
Bracken, A. J.; Watson, P.
2010-10-01
Representations of quantum state vectors by complex phase space amplitudes, complementing the description of the density operator by the Wigner function, have been defined by applying the Weyl-Wigner transform to dyadic operators, linear in the state vector and anti-linear in a fixed 'window state vector'. Here aspects of this construction are explored, and a connection is established with Gabor's 'windowed Fourier transform'. The amplitudes that arise for simple quantum states from various choices of windows are presented as illustrations. Generalized Bargmann representations of the state vector appear as special cases, associated with Gaussian windows. For every choice of window, amplitudes lie in a corresponding linear subspace of square-integrable functions on phase space. A generalized Born interpretation of amplitudes is described, with both the Wigner function and a generalized Husimi function appearing as quantities linear in an amplitude and anti-linear in its complex conjugate. Schrödinger's time-dependent and time-independent equations are represented on phase space amplitudes, and their solutions described in simple cases.
Spiral eigenmodes triggered by grooves in the phase space of disc galaxies
NASA Astrophysics Data System (ADS)
De Rijcke, S.; Voulis, I.
2016-02-01
We use linear perturbation theory to investigate how a groove in the phase space of a disc galaxy changes the stellar disc's stability properties. Such a groove is a narrow trough around a fixed angular momentum from which most stars have been removed, rendering part of the disc unresponsive to spiral waves. We find that a groove can dramatically alter a disc's eigenmode spectrum by giving rise to a set of vigorously growing eigenmodes. These eigenmodes are particular to the grooved disc and are absent from the original ungrooved disc's mode spectrum. We discuss the properties and possible origin of the different families of new modes. By the very nature of our technique, we prove that a narrow phase-space groove can be a source of rapidly growing spiral patterns that are true eigenmodes of the grooved disc and that no non-linear processes need to be invoked to explain their presence in N-body simulations of disc galaxies. Our results lend support to the idea that spiral structure can be a recurrent phenomenon, in which one generation of spiral modes alters a disc galaxy's phase space in such a way that a following generation of modes is destabilized.
High-order continuum kinetic method for modeling plasma dynamics in phase space
Vogman, G. V.; Colella, P.; Shumlak, U.
2014-12-15
Continuum methods offer a high-fidelity means of simulating plasma kinetics. While computationally intensive, these methods are advantageous because they can be cast in conservation-law form, are not susceptible to noise, and can be implemented using high-order numerical methods. Advances in continuum method capabilities for modeling kinetic phenomena in plasmas require the development of validation tools in higher dimensional phase space and an ability to handle non-cartesian geometries. To that end, a new benchmark for validating Vlasov-Poisson simulations in 3D (x,v_{x},v_{y}) is presented. The benchmark is based on the Dory-Guest-Harris instability and is successfully used to validate a continuum finite volume algorithm. To address challenges associated with non-cartesian geometries, unique features of cylindrical phase space coordinates are described. Preliminary results of continuum kinetic simulations in 4D (r,z,v_{r},v_{z}) phase space are presented.
NASA Astrophysics Data System (ADS)
Vaisberg, O.
Evolution of corpuscular diagnostics of space plasmas led to development of very sophisticated plasma spectrometers. There are very specialized spectrometers providing unique identification of mass, energy and charge. Top-hat analyzer became the working horse of contemporary plasma diagnostics on most of spin-stabilized spacecraft. Miniaturized plasma analyzers are developed for new low-cost missions. Still there is a need for instruments with higher temporal resolution and better phase space coverage. Representative examples of high-end plasma analyzers are presented and the trends in corpuscular diagnostics of space plasma are discussed. The new type of plasma analyzer CAMERA is described that allows fast measurements on stabilized or rotating spacecraft. It provides instantaneous 2π field of view without gaps, flexible control of the energy bandwidth and angular resolution, high temporal resolution, and high UV rejection. CAMERA can be used as a feeding optics for additional analyzers including mass-spectrometers.
NASA Astrophysics Data System (ADS)
Santos, Jonas F. G.; Bernardini, Alex E.; Bastos, Catarina
2015-11-01
Novel quantization properties related to the state vectors and the energy spectrum of a two-dimensional system of free particles are obtained in the framework of noncommutative (NC) quantum mechanics (QM) supported by the Weyl-Wigner formalism. Besides reproducing the magnetic field aspect of a Zeeman-like effect, the momentum space NC parameter introduces mutual information properties quantified by the quantum purity related to the relevant coordinates of the corresponding Hilbert space. Supported by the QM in the phase-space, the thermodynamic limit is obtained, and the results are extended to three-dimensional systems. The noncommutativity imprints on the thermodynamic variables related to free particles are identified and, after introducing some suitable constraints to fix an axial symmetry, the analysis is extended to two- and- three dimensional quantum rotor systems, for which the quantization aspects and the deviation from standard QM results are verified.
The Harmonic Oscillator Influenced by Gravitational Wave in Noncommutative Quantum Phase Space
NASA Astrophysics Data System (ADS)
Yakup, Rehimhaji; Dulat, Sayipjamal; Li, Kang; Hekim, Mamatabdulla
2014-04-01
Dynamical property of harmonic oscillator affected by linearized gravitational wave (LGW) is studied in a particular case of both position and momentum operators which are noncommutative to each other. By using the generalized Bopp's shift, we, at first, derived the Hamiltonian in the noncommutative phase space (NPS) and, then, calculated the time evolution of coordinate and momentum operators in the Heisenberg representation. Tiny vibration of flat Minkowski space and effect of NPS let the Hamiltonian of harmonic oscillator, moving in the plain, get new extra terms from it's original and noncommutative space partner. At the end, for simplicity, we take the general form of the LGW into gravitational plain wave, obtain the explicit expression of coordinate and momentum operators.
Phase space effects on fast ion distribution function modeling in tokamaks
NASA Astrophysics Data System (ADS)
Podestà, M.; Gorelenkova, M.; Fredrickson, E. D.; Gorelenkov, N. N.; White, R. B.
2016-05-01
Integrated simulations of tokamak discharges typically rely on classical physics to model energetic particle (EP) dynamics. However, there are numerous cases in which energetic particles can suffer additional transport that is not classical in nature. Examples include transport by applied 3D magnetic perturbations and, more notably, by plasma instabilities. Focusing on the effects of instabilities, ad-hoc models can empirically reproduce increased transport, but the choice of transport coefficients is usually somehow arbitrary. New approaches based on physics-based reduced models are being developed to address those issues in a simplified way, while retaining a more correct treatment of resonant wave-particle interactions. The kick model implemented in the tokamak transport code TRANSP is an example of such reduced models. It includes modifications of the EP distribution by instabilities in real and velocity space, retaining correlations between transport in energy and space typical of resonant EP transport. The relevance of EP phase space modifications by instabilities is first discussed in terms of predicted fast ion distribution. Results are compared with those from a simple, ad-hoc diffusive model. It is then shown that the phase-space resolved model can also provide additional insight into important issues such as internal consistency of the simulations and mode stability through the analysis of the power exchanged between energetic particles and the instabilities.
Phase space effects on fast ion distribution function modeling in tokamaks
Podesta, M.; Gorelenkova, M.; Fredrickson, E. D.; Gorelenkov, N. N.; White, R. B.
2016-04-14
Here, integrated simulations of tokamak discharges typically rely on classical physics to model energetic particle (EP) dynamics. However, there are numerous cases in which energetic particles can suffer additional transport that is not classical in nature. Examples include transport by applied 3D magnetic perturbations and, more notably, by plasma instabilities. Focusing on the effects of instabilities,ad-hocmodels can empirically reproduce increased transport, but the choice of transport coefficients is usually somehow arbitrary. New approaches based on physics-based reduced models are being developed to address those issues in a simplified way, while retaining a more correct treatment of resonant wave-particle interactions. Themore » kick model implemented in the tokamaktransport code TRANSP is an example of such reduced models. It includes modifications of the EP distribution by instabilities in real and velocity space, retaining correlations between transport in energy and space typical of resonant EP transport. The relevance of EP phase space modifications by instabilities is first discussed in terms of predicted fast ion distribution. Results are compared with those from a simple, ad-hoc diffusive model. It is then shown that the phase-space resolved model can also provide additional insight into important issues such as internal consistency of the simulations and mode stability through the analysis of the power exchanged between energetic particles and the instabilities.« less
Image inversion analysis of the HST OTA (Hubble Space Telescope Optical Telescope Assembly), phase A
NASA Technical Reports Server (NTRS)
Litvak, M. M.
1991-01-01
Technical work during September-December 1990 consisted of: (1) analyzing HST point source images obtained from JPL; (2) retrieving phase information from the images by a direct (noniterative) technique; and (3) characterizing the wavefront aberration due to the errors in the Hubble Space Telescope (HST) mirrors, in a preliminary manner. This work was in support of JPL design of compensating optics for the next generation wide-field planetary camera on HST. This digital technique for phase retrieval from pairs of defocused images, is based on the energy transport equation between these image planes. In addition, an end-to-end wave optics routine, based on the JPL Code 5 prescription of the unaberrated HST and WFPC, was derived for output of the reference phase front when mirror error is absent. Also, the Roddier routine unwrapped the retrieved phase by inserting the required jumps of +/- 2(pi) radians for the sake of smoothness. A least-squares fitting routine, insensitive to phase unwrapping, but nonlinear, was used to obtain estimates of the Zernike polynomial coefficients that describe the aberration. The phase results were close to, but higher than, the expected error in conic constant of the primary mirror suggested by the fossil evidence. The analysis of aberration contributed by the camera itself could be responsible for the small discrepancy, but was not verified by analysis.
NASA Astrophysics Data System (ADS)
Naqvi, Shahid A.; D'Souza, Warren D.; Earl, Matthew A.; Ye, Sung-Joon; Shih, Rompin; Li, X. Allen
2005-09-01
For a given linac design, the dosimetric characteristics of a photon beam are determined uniquely by the energy and radial distributions of the electron beam striking the x-ray target. However, in the usual commissioning of a beam from measured data, a large number of variables can be independently tuned, making it difficult to derive a unique and self-consistent beam model. For example, the measured dosimetric penumbra in water may be attributed in various proportions to the lateral secondary electron range, the focal spot size and the transmission through the tips of a non-divergent collimator; the head-scatter component in the tails of the transverse profiles may not be easy to resolve from phantom scatter and head leakage; and the head-scatter tails corresponding to a certain extra-focal source model may not agree self-consistently with in-air output factors measured on the central axis. To reduce the number of adjustable variables in beam modelling, we replace the focal and extra-focal sources with a single phase-space plane scored just above the highest adjustable collimator in a EGS/BEAM simulation of the linac. The phase-space plane is then used as photon source in a stochastic convolution/superposition dose engine. A photon sampled from the uncollimated phase-space plane is first propagated through an arbitrary collimator arrangement and then interacted in the simulation phantom. Energy deposition kernel rays are then randomly issued from the interaction points and dose is deposited along these rays. The electrons in the phase-space file are used to account for electron contamination. 6 MV and 18 MV photon beams from an Elekta SL linac are used as representative examples. Except for small corrections for monitor backscatter and collimator forward scatter for large field sizes (<0.5% with <20 × 20 cm2 field size), we found that the use of a single phase-space photon source provides accurate and self-consistent results for both relative and absolute dose
NASA Technical Reports Server (NTRS)
Beisert, Susan; Rodriggs, Michael; Moreno, Francisco; Korth, David; Gibson, Stephen; Lee, Young H.; Eagles, Donald E.
2013-01-01
Now that major assembly of the International Space Station (ISS) is complete, NASA's focus has turned to using this high fidelity in-space research testbed to not only advance fundamental science research, but also demonstrate and mature technologies and develop operational concepts that will enable future human exploration missions beyond low Earth orbit. The ISS as a Testbed for Analog Research (ISTAR) project was established to reduce risks for manned missions to exploration destinations by utilizing ISS as a high fidelity micro-g laboratory to demonstrate technologies, operations concepts, and techniques associated with crew autonomous operations. One of these focus areas is the development and execution of ISS Testbed for Analog Research (ISTAR) autonomous flight crew procedures intended to increase crew autonomy that will be required for long duration human exploration missions. Due to increasing communications delays and reduced logistics resupply, autonomous procedures are expected to help reduce crew reliance on the ground flight control team, increase crew performance, and enable the crew to become more subject-matter experts on both the exploration space vehicle systems and the scientific investigation operations that will be conducted on a long duration human space exploration mission. These tests make use of previous or ongoing projects tested in ground analogs such as Research and Technology Studies (RATS) and NASA Extreme Environment Mission Operations (NEEMO). Since the latter half of 2012, selected non-critical ISS systems crew procedures have been used to develop techniques for building ISTAR autonomous procedures, and ISS flight crews have successfully executed them without flight controller involvement. Although the main focus has been preparing for exploration, the ISS has been a beneficiary of this synergistic effort and is considering modifying additional standard ISS procedures that may increase crew efficiency, reduce operational costs, and
NASA Astrophysics Data System (ADS)
Lepine, Sebastien
2016-05-01
The potential of future large astrometric catalogs for mapping the velocity-space distribution of local stars in the Galaxy is illustrated with a kinematic study of K and M dwarfs in the SUPERBLINK catalog of 2.5 million stars with large proper motions (mu>40 mas/yr). Low mass K and M dwarfs, found in abundance thanks to the faint magnitude limit of the catalog (V<20) provide the densest possible sampling of the [(X,Y,Z),(U,V,W)] phase-space, making them well-suited to map out substructure (so-called "streams") in the velocity-space distributions, as well as variations in said distribution over >100 parsec scale distances. The SUPERBLINK proper motion catalog thus provides kinematic data for ~1.5 million M dwarfs from the Galactic disk population, located within 200 parsecs of the Sun, and for ~180,000 K and M (sub)dwarfs from the Galactic halo population, all within 500 parsecs of the Sun. While the disk dwarfs show clear signs of velocity-space substructure, the distribution of halo subdwarf does appear to be relatively smooth ("streamless") in contrast. Evidence for spatial variations at the few hundred parsec scale is also discussed. The current and unfortunately "blurry" view of the local velocity-space distribution promises to be set in much sharper focus with the upcoming availability of data from the GAIA mission.
NASA Astrophysics Data System (ADS)
Hahn, Oliver; Angulo, Raul E.
2016-01-01
N-body simulations are essential for understanding the formation and evolution of structure in the Universe. However, the discrete nature of these simulations affects their accuracy when modelling collisionless systems. We introduce a new approach to simulate the gravitational evolution of cold collisionless fluids by solving the Vlasov-Poisson equations in terms of adaptively refineable `Lagrangian phase-space elements'. These geometrical elements are piecewise smooth maps between Lagrangian space and Eulerian phase-space and approximate the continuum structure of the distribution function. They allow for dynamical adaptive splitting to accurately follow the evolution even in regions of very strong mixing. We discuss in detail various one-, two- and three-dimensional test problems to demonstrate the performance of our method. Its advantages compared to N-body algorithms are: (i) explicit tracking of the fine-grained distribution function, (ii) natural representation of caustics, (iii) intrinsically smooth gravitational potential fields, thus (iv) eliminating the need for any type of ad hoc force softening. We show the potential of our method by simulating structure formation in a warm dark matter scenario. We discuss how spurious collisionality and large-scale discreteness noise of N-body methods are both strongly suppressed, which eliminates the artificial fragmentation of filaments. Therefore, we argue that our new approach improves on the N-body method when simulating self-gravitating cold and collisionless fluids, and is the first method that allows us to explicitly follow the fine-grained evolution in six-dimensional phase-space.
Synchronization in area-preserving maps: Effects of mixed phase space and coherent structures
NASA Astrophysics Data System (ADS)
Mahata, Sasibhusan; Das, Swetamber; Gupte, Neelima
2016-06-01
The problem of synchronization of coupled Hamiltonian systems presents interesting features due to the mixed nature (regular and chaotic) of the phase space. We study these features by examining the synchronization of unidirectionally coupled area-preserving maps coupled by the Pecora-Caroll method. The master stability function approach is used to study the stability of the synchronous state and to identify the percentage of synchronizing initial conditions. The transient to synchronization shows intermittency with an associated power law. The mixed nature of the phase space of the studied map has notable effects on the synchronization times as is seen in the case of the standard map. Using finite-time Lyapunov exponent analysis, we show that the synchronization of the maps occurs in the neighborhood of invariant curves in the phase space. The phase differences of the coevolving trajectories show intermittency effects, due to the existence of stable periodic orbits contributing locally stable directions in the synchronizing neighborhoods. Furthermore, the value of the nonlinearity parameter, as well as the location of the initial conditions play an important role in the distribution of synchronization times. We examine drive response combinations which are chaotic-chaotic, chaotic-regular, regular-chaotic, and regular-regular. A range of scaling behavior is seen for these cases, including situations where the distributions show a power-law tail, indicating long synchronization times for at least some of the synchronizing trajectories. The introduction of coherent structures in the system changes the situation drastically. The distribution of synchronization times crosses over to exponential behavior, indicating shorter synchronization times, and the number of initial conditions which synchronize increases significantly, indicating an enhancement in the basin of synchronization. We discuss the implications of our results.
Synchronization in area-preserving maps: Effects of mixed phase space and coherent structures.
Mahata, Sasibhusan; Das, Swetamber; Gupte, Neelima
2016-06-01
The problem of synchronization of coupled Hamiltonian systems presents interesting features due to the mixed nature (regular and chaotic) of the phase space. We study these features by examining the synchronization of unidirectionally coupled area-preserving maps coupled by the Pecora-Caroll method. The master stability function approach is used to study the stability of the synchronous state and to identify the percentage of synchronizing initial conditions. The transient to synchronization shows intermittency with an associated power law. The mixed nature of the phase space of the studied map has notable effects on the synchronization times as is seen in the case of the standard map. Using finite-time Lyapunov exponent analysis, we show that the synchronization of the maps occurs in the neighborhood of invariant curves in the phase space. The phase differences of the coevolving trajectories show intermittency effects, due to the existence of stable periodic orbits contributing locally stable directions in the synchronizing neighborhoods. Furthermore, the value of the nonlinearity parameter, as well as the location of the initial conditions play an important role in the distribution of synchronization times. We examine drive response combinations which are chaotic-chaotic, chaotic-regular, regular-chaotic, and regular-regular. A range of scaling behavior is seen for these cases, including situations where the distributions show a power-law tail, indicating long synchronization times for at least some of the synchronizing trajectories. The introduction of coherent structures in the system changes the situation drastically. The distribution of synchronization times crosses over to exponential behavior, indicating shorter synchronization times, and the number of initial conditions which synchronize increases significantly, indicating an enhancement in the basin of synchronization. We discuss the implications of our results. PMID:27415260
Aydin, Ilhan; Karakose, Mehmet; Akin, Erhan
2014-03-01
Although reconstructed phase space is one of the most powerful methods for analyzing a time series, it can fail in fault diagnosis of an induction motor when the appropriate pre-processing is not performed. Therefore, boundary analysis based a new feature extraction method in phase space is proposed for diagnosis of induction motor faults. The proposed approach requires the measurement of one phase current signal to construct the phase space representation. Each phase space is converted into an image, and the boundary of each image is extracted by a boundary detection algorithm. A fuzzy decision tree has been designed to detect broken rotor bars and broken connector faults. The results indicate that the proposed approach has a higher recognition rate than other methods on the same dataset. PMID:24296116
NASA Technical Reports Server (NTRS)
Singh, Bhim S.
2003-01-01
NASA is preparing to undertake science-driven exploration missions. The NASA Exploration Team's vision is a cascade of stepping stones. The stepping-stone will build the technical capabilities needed for each step with multi-use technologies and capabilities. An Agency-wide technology investment and development program is necessary to implement the vision. The NASA Exploration Team has identified a number of areas where significant advances are needed to overcome all engineering and medical barriers to the expansion of human space exploration beyond low-Earth orbit. Closed-loop life support systems and advanced propulsion and power technologies are among the areas requiring significant advances from the current state-of-the-art. Studies conducted by the National Academy of Science's National Research Council and Workshops organized by NASA have shown that multiphase flow and phase change play a crucial role in many of these advanced technology concepts. Lack of understanding of multiphase flow, phase change, and interfacial phenomena in the microgravity environment has been a major hurdle. An understanding of multiphase flow and phase change in microgravity is, therefore, critical to advancing many technologies needed. Recognizing this, the Office of Biological and Physical Research (OBPR) has initiated a strategic research thrust to augment the ongoing fundamental research in fluid physics and transport phenomena discipline with research especially aimed at understanding key multiphase flow related issues in propulsion, power, thermal control, and closed-loop advanced life support systems. A plan for integrated theoretical and experimental research that has the highest probability of providing data, predictive tools, and models needed by the systems developers to incorporate highly promising multiphase-based technologies is currently in preparation. This plan is being developed with inputs from scientific community, NASA mission planners and industry personnel
Development of a prototype two-phase thermal bus system for Space Station
NASA Technical Reports Server (NTRS)
Myron, D. L.; Parish, R. C.
1987-01-01
This paper describes the basic elements of a pumped two-phase ammonia thermal control system designed for microgravity environments, the development of the concept into a Space Station flight design, and design details of the prototype to be ground-tested in the Johnson Space Center (JSC) Thermal Test Bed. The basic system concept is one of forced-flow heat transport through interface heat exchangers with anhydrous ammonia being pumped by a device expressly designed for two-phase fluid management in reduced gravity. Control of saturation conditions, and thus system interface temperatures, is accomplished with a single central pressure regulating valve. Flow control and liquid inventory are controlled by passive, nonelectromechanical devices. Use of these simple control elements results in minimal computer controls and high system reliability. Building on the basic system concept, a brief overview of a potential Space Station flight design is given. Primary verification of the system concept will involve testing at JSC of a 25-kW ground test article currently in fabrication.
Space shuttle phase B wind tunnel model and test information. Volume 2: Orbiter configuration
NASA Technical Reports Server (NTRS)
Glynn, J. L.; Poucher, D. E.
1988-01-01
Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a data base and are available for applying to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Data Base is structured by vehicle component and configuration type. Basic components include the booster, the orbiter, and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retro-glide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configuration types include booster and orbiter components in various stacked and tandem combinations.
Space shuttle phase B wind tunnel model and test information. Volume 3: Launch configuration
NASA Technical Reports Server (NTRS)
Glynn, J. L.; Poucher, D. E.
1988-01-01
Archived wind tunnel data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel data acquired in the Phase B development have been compiled into a data base and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include booster, orbiter and launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbital configuration types include straight and delta wings, lifting body, drop tanks and double delta wings. This is Volume 3 (Part 2) of the report -- Launch Configuration -- which includes booster and orbiter components in various stacked and tandem combinations.
Space shuttle phase B wind tunnel model and test information. Volume 1: Booster configuration
NASA Technical Reports Server (NTRS)
Glynn, J. L.; Poucher, D. E.
1988-01-01
Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configurations include booster and orbiter components in various stacked and tandem combinations. This is Volume 1 (Part 1) of the report -- Booster Configuration.
Space shuttle phase B wind tunnel model and test information. Volume 2: Orbiter configuration
NASA Technical Reports Server (NTRS)
Glynn, J. L.; Poucher, D. E.
1988-01-01
Archived wind tunnel test data are available for flyback booster or other alternate recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquiredin the Phase B development have been compiled into a database and are available for applying to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter, and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide, and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks, and double delta wings. Launch configration types include booster and orbiter components in various stacked and tandom combinations. The digital database consists of 220 files of data containing basic tunnel recorded data.
Space shuttle phase B wind tunnel model and test information. Volume 1: Booster configuration
NASA Technical Reports Server (NTRS)
Glynn, J. L.; Poucher, D. E.
1988-01-01
Archived wind tunnel test data are available for flyback booster or other alternative recoverable configurations as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle. Considerable wind tunnel data was acquired by the competing contractors and the NASA Centers for an extensive variety of configurations with an array of wing and body planforms. All contractor and NASA wind tunnel test data acquired in the Phase B development have been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration type. Basic components include the booster, the orbiter, and the launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbiter configuration types include straight and delta wings, lifting body, drop tanks and double delta wings. Launch configurations include booster and orbiter components in various stacked and tandem combinations. This is Volume 1 (Part 2) of the report -- Booster Configuration.
Fully integrated hybrid silicon free-space beam steering source with 32-channel phased array
NASA Astrophysics Data System (ADS)
Hulme, J. C.; Doylend, J. K.; Heck, M. J. R.; Peters, J. D.; Davenport, M. L.; Bovington, J. T.; Coldren, L. A.; Bowers, J. E.
2014-03-01
Free-space beam steering using optical phased arrays is a promising method for implementing free-space communication links and Light Detection and Ranging (LIDAR) without the sensitivity to inertial forces and long latencies which characterize moving parts. Implementing this approach on a silicon-based photonic integrated circuit adds the additional advantage of working with highly developed CMOS processing techniques. In this work we discuss our progress in the development of a fully integrated 32 channel PIC with a widely tunable diode laser, a waveguide phased array, an array of fast phase modulators, an array of hybrid III-V/silicon amplifiers, surface gratings, and a graded index lens (GRIN) feeding an array of photodiodes for feedback control. The PIC has been designed to provide beam steering across a 15°x5° field of view with 0.6°x0.6° beam width and background peaks suppressed 15 dB relative to the main lobe within the field of view for arbitrarily chosen beam directions. Fabrication follows the hybrid silicon process developed at UCSB with modifications to incorporate silicon diodes and a GRIN lens.
Phase change cells and the verification of gallium as a thermal calibration reference in space
NASA Astrophysics Data System (ADS)
Latvikoski, Harri; Bingham, Gail E.; Topham, T. S.; Podolski, Igor
2015-09-01
The validation of models of global climate change and accurate measurement of the atmosphere and surface temperatures require that orbital sensors have low drift rates, and are monitored or regularly recalibrated by accepted standards. Phase change materials (PCM), such as those that make up the ITS-90 standard, are the basis for international commerce and have been suggested for monitoring and recalibration of orbital temperature sensors. Space Dynamics Laboratory (SDL) and its partners have been developing miniaturized phase change reference technologies that could be deployed on an orbital blackbody for nearly a decade. A significant part of this effort has been the exploration of the behavior of gallium (Ga) and its eutectics, gallium-tin (GaSn) and gallium-indium (GaIn) in conditions expected to be encountered in this application. In this paper, these behaviors are detailed and an example of a hardware design that could be used as an infrared blackbody calibration monitor is presented. To determine if and how microgravity will affect the behavior of Ga, the authors conducted an experiment on the International Space Station (ISS) and compared the observed phase change temperature with earth-based measurements. This paper also provides a brief description of the experiment hardware, microgravity considerations, and the pre-flight, flight and post-flight data analysis.
Space-Based Telemetry and Range Safety Project Ku-Band and Ka-Band Phased Array Antenna
NASA Technical Reports Server (NTRS)
Whiteman, Donald E.; Valencia, Lisa M.; Birr, Richard B.
2005-01-01
The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to increase data rates and flexibility and decrease costs by using space-based communications assets for telemetry during launches and landings. Phase 1 used standard S-band antennas with the Tracking and Data Relay Satellite System to obtain a baseline performance. The selection process and available resources for Phase 2 resulted in a Ku-band phased array antenna system. Several development efforts are under way for a Ka-band phased array antenna system for Phase 3. Each phase includes test flights to demonstrate performance and capabilities. Successful completion of this project will result in a set of communications requirements for the next generation of launch vehicles.
Ku- and Ka-Band Phased Array Antenna for the Space-Based Telemetry and Range Safety Project
NASA Technical Reports Server (NTRS)
Whiteman, Donald E.; Valencia, Lisa M.; Birr, Richard B.
2005-01-01
The National Aeronautics and Space Administration Space-Based Telemetry and Range Safety study is a multiphase project to increase data rates and flexibility and decrease costs by using space-based communications assets for telemetry during launches and landings. Phase 1 used standard S-band antennas with the Tracking and Data Relay Satellite System to obtain a baseline performance. The selection process and available resources for Phase 2 resulted in a Ku-band phased array antenna system. Several development efforts are under way for a Ka-band phased array antenna system for Phase 3. Each phase includes test flights to demonstrate performance and capabilities. Successful completion of this project will result in a set of communications requirements for the next generation of launch vehicles.
Solving the inverse Ising problem by mean-field methods in a clustered phase space with many states
NASA Astrophysics Data System (ADS)
Decelle, Aurélien; Ricci-Tersenghi, Federico
2016-07-01
In this work we explain how to properly use mean-field methods to solve the inverse Ising problem when the phase space is clustered, that is, many states are present. The clustering of the phase space can occur for many reasons, e.g., when a system undergoes a phase transition, but also when data are collected in different regimes (e.g., quiescent and spiking regimes in neural networks). Mean-field methods for the inverse Ising problem are typically used without taking into account the eventual clustered structure of the input configurations and may lead to very poor inference (e.g., in the low-temperature phase of the Curie-Weiss model). In this work we explain how to modify mean-field approaches when the phase space is clustered and we illustrate the effectiveness of our method on different clustered structures (low-temperature phases of Curie-Weiss and Hopfield models).
Solving the inverse Ising problem by mean-field methods in a clustered phase space with many states.
Decelle, Aurélien; Ricci-Tersenghi, Federico
2016-07-01
In this work we explain how to properly use mean-field methods to solve the inverse Ising problem when the phase space is clustered, that is, many states are present. The clustering of the phase space can occur for many reasons, e.g., when a system undergoes a phase transition, but also when data are collected in different regimes (e.g., quiescent and spiking regimes in neural networks). Mean-field methods for the inverse Ising problem are typically used without taking into account the eventual clustered structure of the input configurations and may lead to very poor inference (e.g., in the low-temperature phase of the Curie-Weiss model). In this work we explain how to modify mean-field approaches when the phase space is clustered and we illustrate the effectiveness of our method on different clustered structures (low-temperature phases of Curie-Weiss and Hopfield models). PMID:27575082
Zhou, F.; Kabel, A.; Rosenzweig, J.; Agustsson, R.; Andonian, G.; Cline, D.; Murokh, A.; Yakimenko, V.; /UCLA /SLAC /Brookhaven
2007-02-12
Space charge and coherent synchrotron radiation may deteriorate electron beam quality when the beam passes through a magnetic bunch compressor. This paper presents the transverse phase-space tomographic measurements for a compressed beam at 60 MeV, around which energy the first stage of magnetic bunch compression takes place in most advanced linacs. Transverse phase-space bifurcation of a compressed beam is observed at that energy, but the degree of the space charge-induced bifurcation is appreciably lower than the one observed at 12 MeV.
Dust environment of an airless object: A phase space study with kinetic models
NASA Astrophysics Data System (ADS)
Kallio, E.; Dyadechkin, S.; Fatemi, S.; Holmström, M.; Futaana, Y.; Wurz, P.; Fernandes, V. A.; Álvarez, F.; Heilimo, J.; Jarvinen, R.; Schmidt, W.; Harri, A.-M.; Barabash, S.; Mäkelä, J.; Porjo, N.; Alho, M.
2016-01-01
The study of dust above the lunar surface is important for both science and technology. Dust particles are electrically charged due to impact of the solar radiation and the solar wind plasma and, therefore, they affect the plasma above the lunar surface. Dust is also a health hazard for crewed missions because micron and sub-micron sized dust particles can be toxic and harmful to the human body. Dust also causes malfunctions in mechanical devices and is therefore a risk for spacecraft and instruments on the lunar surface. Properties of dust particles above the lunar surface are not fully known. However, it can be stated that their large surface area to volume ratio due to their irregular shape, broken chemical bonds on the surface of each dust particle, together with the reduced lunar environment cause the dust particles to be chemically very reactive. One critical unknown factor is the electric field and the electric potential near the lunar surface. We have developed a modelling suite, Dusty Plasma Environments: near-surface characterisation and Modelling (DPEM), to study globally and locally dust environments of the Moon and other airless bodies. The DPEM model combines three independent kinetic models: (1) a 3D hybrid model, where ions are modelled as particles and electrons are modelled as a charged neutralising fluid, (2) a 2D electrostatic Particle-in-Cell (PIC) model where both ions and electrons are treated as particles, and (3) a 3D Monte Carlo (MC) model where dust particles are modelled as test particles. The three models are linked to each other unidirectionally; the hybrid model provides upstream plasma parameters to be used as boundary conditions for the PIC model which generates the surface potential for the MC model. We have used the DPEM model to study properties of dust particles injected from the surface of airless objects such as the Moon, the Martian moon Phobos and the asteroid RQ36. We have performed a (v0, m/q)-phase space study where the
Space charge and beam stability issues of the Fermilab proton driver in Phase I
K. Y. Ng
2001-08-24
Issues concerning beam stability of the proposed Fermilab Proton Driver are studied in its Phase I. Although the betatron tune shifts are dominated by space charge, these shifts are less than 0.25 and will therefore not drive the symmetric and antisymmetric modes of the beam envelope into instability. The longitudinal space charge force is large and inductive inserts may be needed to compensate for the distortion of the rf potential. Although the longitudinal impedance is space charge dominated, it will not drive any microwave instability, unless the real part of the impedance coming from the inductive inserts and wall resistivity of the beam tube are large enough. The design of the beam tube is therefore very important in order to limit the flow of eddy current and keep wall resistivity low. The transverse impedance is also space charge dominated. With the Proton Driver operated at an imaginary transition gamma, however, Landau damping will never be canceled and beam stability can be maintained with negative chromaticities.
Study of selected tether applications in space, phase 3, volume 2
NASA Technical Reports Server (NTRS)
1986-01-01
The results of a Phase 3 study of two Selected Tether Applications in Space (STAIS); deorbit of a Shuttle and launch of an Orbital Transfer Vehicle (OTV), both from the space station using a tether were examined. The study objectives were to: perform a preliminary engineering design, define operational scenarios, develop a common cost model, perform cost benefits analyses, and develop a Work Breakdown Structure (WBS). Key features of the performance analysis were to identify the net increases in effective Shuttle cargo capability if tethers are used to assist in the deorbit of Shuttles and the launching of the OTVs from the space station and to define deployer system designs required to accomplish these tasks. Deployer concepts were designed and discussed. Operational scenarios, including timelines, for both tethered and nontethered Shuttle and OTV operations at the space station were evaluated. A summary discussion of the Selected Tether Applications Cost Model (STACOM) and the results of the cost benefits analysis are presented. Several critical technologies needed to implement tether assisted deployment of payloads are also discussed. Conclusions and recommendations are presented.
Delaney, P.
1984-01-01
Analytical solutions are developed for the pressurization, expansion, and flow of one- and two-phase liquids during heating of fully saturated and hydraulically open Darcian half-spaces subjected to a step rise in temperature at its surface. For silicate materials, advective transfer is commonly unimportant in the liquid region; this is not always the case in the vapor region. Volume change is commonly more important than heat of vaporization in determining the position of the liquid-vapor interface, assuring that the temperatures cannot be determined independently of pressures. Pressure increases reach a maximum near the leading edge of the thermal front and penetrate well into the isothermal region of the body. Mass flux is insensitive to the hydraulic properties of the half-space. ?? 1984.
NASA Astrophysics Data System (ADS)
Bernardini, A. E.; Bertolami, O.
2013-07-01
In this work we examine the effect of phase-space noncommutativity on some typically quantum properties such as quantum beating, quantum information, and decoherence. To exemplify these issues we consider the two-dimensional noncommutative quantum harmonic oscillator whose component behavior we monitor in time. This procedure allows us to determine how the noncommutative parameters are related to the missing information quantified by the linear quantum entropy and by the mutual information between the relevant Hilbert space coordinates. Particular questions concerning the thermodynamic limit of some relevant properties are also discussed in order to evidence the effects of noncommutativity. Finally, through an analogy with the Zeeman effect, we identify how some aspects of the axial symmetry of the problem suggest the possibility of decoupling the noncommutative quantum perturbations from unperturbed commutative well-known solutions.
Phase-space-region operators and the Wigner function: Geometric constructions and tomography
NASA Astrophysics Data System (ADS)
Ellinas, Demosthenes; Bracken, Anthony J.
2008-11-01
Quasiprobability measures on a canonical phase space give rise through the action of Weyl’s quantization map to operator-valued measures and, in particular, to region operators. Spectral properties, transformations, and general construction methods of such operators are investigated. Geometric trace-increasing maps of density operators are introduced for the construction of region operators associated with one-dimensional domains, as well as with two-dimensional shapes (segments, canonical polygons, lattices, etc.). Operational methods are developed that implement such maps in terms of unitary operations by introducing extensions of the original quantum system with ancillary spaces (qubits). Tomographic methods of reconstruction of the Wigner function based on the radon transform technique are derived by the construction methods for region operators. A Hamiltonian realization of the region operator associated with the radon transform is provided, together with physical interpretations.
Simulation of Phased Array Wide-Field of View Radars for Space Surveillance
NASA Astrophysics Data System (ADS)
Gelhause, J.; Flegel, S.; Wiedemann, C.; Vorsmann, P.; Stabroth, S.; Wagner, A.; Klinkrad, H.
2009-03-01
Europe intends to develop its own Space Surveillance System as part of a more comprehensive Space Situational Awareness System. In the design process, simulations help to determine appropriate system architectures for given user requirements. In order to provide such a simulation environment, the ESA Program for Radar and Optical Observation Forecasting (PROOF) can be applied. The existing model for phased-array radar simulations only takes into account a simplified antenna pattern. A new simulation approach is envisaged within a current PROOF software upgrade. It considers the complete scanning area as a single field-of-view, with borders of the scanning area defined relative to the line of sight, and with path offsets randomly selected to cover the scanning area.
Different phases of hairy black holes in AdS5 space
NASA Astrophysics Data System (ADS)
Giribet, Gaston; Goya, Andrés; Oliva, Julio
2015-02-01
We investigate the thermodynamics of hairy black holes in asymptotically anti-de Sitter (AdS) space, including backreaction. Resorting to the Euclidean path integral approach, we show that matter conformally coupled to Einstein gravity in five dimensions may exhibit a phase transition whose endpoint turns out to be a hairy black hole in AdS5 space. The scalar field configuration happens to be regular everywhere outside and on the horizon and behaves asymptotically in such a way that respects the AdS boundary conditions that are relevant for AdS/CFT. The theory presents other peculiar features in the ultraviolet, like the existence of black holes with arbitrarily low temperature in AdS5 . This provides a simple setup in which the fully backreacting problem of a hair forming in AdS at a certain critical temperature can be solved analytically.
Phase space matching and finite lifetime effects for top-pair production close to threshold
Hoang, Andre H.; Reisser, Christoph J.; Ruiz-Femenia, Pedro
2010-07-01
The top-pair tt production cross section close to threshold in e{sup +}e{sup -} collisions is strongly affected by the small lifetime of the top quark. Since the cross section is defined through final states containing the top decay products, a consistent definition of the cross section depends on prescriptions of how these final states are accounted for the cross section. Experimentally, these prescriptions are implemented, for example, through cuts on kinematic quantities such as the reconstructed top quark invariant masses. As long as these cuts do not reject final states that can arise from the decay of a top and an antitop quark with a small off-shellness compatible with the nonrelativistic power counting, they can be implemented through imaginary phase space matching conditions in nonrelativistic QCD. The prescription-dependent cross section can then be determined from the optical theorem using the e{sup +}e{sup -} forward scattering amplitude. We compute the phase space matching conditions associated to cuts on the top and antitop invariant masses at next-to-next-to-leading logarithmic order and partially at next-to-next-to-next-to-leading logarithmic order in the nonrelativistic expansion accounting also for higher order QCD effects. Together with finite lifetime and electroweak effects known from previous work, we analyze their numerical impact on the tt cross section. We show that the phase space matching contributions are essential to make reliable nonrelativistic QCD predictions, particularly for energies below the peak region, where the cross section is small. We find that irreducible background contributions associated to final states that do not come from top decays are strongly suppressed and can be neglected for the theoretical predictions.
NASA Astrophysics Data System (ADS)
Mauguière, Frédéric A. L.; Collins, Peter; Ezra, Gregory S.; Farantos, Stavros C.; Wiggins, Stephen
2014-04-01
A model Hamiltonian for the reaction CH_4^+ rArr CH_3^+ + H, parametrized to exhibit either early or late inner transition states, is employed to investigate the dynamical characteristics of the roaming mechanism. Tight/loose transition states and conventional/roaming reaction pathways are identified in terms of time-invariant objects in phase space. These are dividing surfaces associated with normally hyperbolic invariant manifolds (NHIMs). For systems with two degrees of freedom NHIMS are unstable periodic orbits which, in conjunction with their stable and unstable manifolds, unambiguously define the (locally) non-recrossing dividing surfaces assumed in statistical theories of reaction rates. By constructing periodic orbit continuation/bifurcation diagrams for two values of the potential function parameter corresponding to late and early transition states, respectively, and using the total energy as another parameter, we dynamically assign different regions of phase space to reactants and products as well as to conventional and roaming reaction pathways. The classical dynamics of the system are investigated by uniformly sampling trajectory initial conditions on the dividing surfaces. Trajectories are classified into four different categories: direct reactive and non-reactive trajectories, which lead to the formation of molecular and radical products respectively, and roaming reactive and non-reactive orbiting trajectories, which represent alternative pathways to form molecular and radical products. By analysing gap time distributions at several energies, we demonstrate that the phase space structure of the roaming region, which is strongly influenced by nonlinear resonances between the two degrees of freedom, results in nonexponential (nonstatistical) decay.
Non-power law behavior of the radial profile of phase-space density of halos
Popolo, A. Del
2011-07-01
We study the pseudo phase-space density, ρ(r)/σ{sup 3}(r), of ΛCDM dark matter halos with and without baryons (baryons+DM, and pure DM), by using the model introduced in Del Popolo (2009), which takes into account the effect of dynamical friction, ordered and random angular momentum, baryons adiabatic contraction and dark matter baryons interplay. We examine the radial dependence of ρ(r)/σ{sup 3}(r) over 9 orders of magnitude in radius for structures on galactic and cluster of galaxies scales. We find that ρ(r)/σ{sup 3}(r) is approximately a power-law only in the range of halo radius resolved by current simulations (down to 0.1% of the virial radius) while it has a non-power law behavior below the quoted scale, with inner profiles changing with mass. The non-power-law behavior is more evident for halos constituted both of dark matter and baryons while halos constituted just of dark matter and with angular momentum chosen to reproduce a Navarro-Frenk-White (NFW) density profile, are characterized by an approximately power-law behavior. The results of the present paper lead to conclude that density profiles of the NFW type are compatible with a power-law behavior of ρ(r)/σ{sup 3}(r), while those flattening to the halo center, like those found in Del Popolo (2009) or the Einasto profile, or the Burkert profile, cannot produce radial profile of the pseudo-phase-space density that are power-laws at all radii. The results argue against universality of the pseudo phase-space density and as a consequence argue against universality of density profiles constituted by dark matter and baryons as also discussed in Del Popolo (2009)
Mid- and long-term runoff predictions by an improved phase-space reconstruction model.
Hong, Mei; Wang, Dong; Wang, Yuankun; Zeng, Xiankui; Ge, Shanshan; Yan, Hengqian; Singh, Vijay P
2016-07-01
In recent years, the phase-space reconstruction method has usually been used for mid- and long-term runoff predictions. However, the traditional phase-space reconstruction method is still needs to be improved. Using the genetic algorithm to improve the phase-space reconstruction method, a new nonlinear model of monthly runoff is constructed. The new model does not rely heavily on embedding dimensions. Recognizing that the rainfall-runoff process is complex, affected by a number of factors, more variables (e.g. temperature and rainfall) are incorporated in the model. In order to detect the possible presence of chaos in the runoff dynamics, chaotic characteristics of the model are also analyzed, which shows the model can represent the nonlinear and chaotic characteristics of the runoff. The model is tested for its forecasting performance in four types of experiments using data from six hydrological stations on the Yellow River and the Yangtze River. Results show that the medium-and long-term runoff is satisfactorily forecasted at the hydrological stations. Not only is the forecasting trend accurate, but also the mean absolute percentage error is no more than 15%. Moreover, the forecast results of wet years and dry years are both good, which means that the improved model can overcome the traditional ''wet years and dry years predictability barrier,'' to some extent. The model forecasts for different regions are all good, showing the universality of the approach. Compared with selected conceptual and empirical methods, the model exhibits greater reliability and stability in the long-term runoff prediction. Our study provides a new thinking for research on the association between the monthly runoff and other hydrological factors, and also provides a new method for the prediction of the monthly runoff. PMID:26632992
Phase-space finite elements in a least-squares solution of the transport equation
Drumm, C.; Fan, W.; Pautz, S.
2013-07-01
The linear Boltzmann transport equation is solved using a least-squares finite element approximation in the space, angular and energy phase-space variables. The method is applied to both neutral particle transport and also to charged particle transport in the presence of an electric field, where the angular and energy derivative terms are handled with the energy/angular finite elements approximation, in a manner analogous to the way the spatial streaming term is handled. For multi-dimensional problems, a novel approach is used for the angular finite elements: mapping the surface of a unit sphere to a two-dimensional planar region and using a meshing tool to generate a mesh. In this manner, much of the spatial finite-elements machinery can be easily adapted to handle the angular variable. The energy variable and the angular variable for one-dimensional problems make use of edge/beam elements, also building upon the spatial finite elements capabilities. The methods described here can make use of either continuous or discontinuous finite elements in space, angle and/or energy, with the use of continuous finite elements resulting in a smaller problem size and the use of discontinuous finite elements resulting in more accurate solutions for certain types of problems. The work described in this paper makes use of continuous finite elements, so that the resulting linear system is symmetric positive definite and can be solved with a highly efficient parallel preconditioned conjugate gradients algorithm. The phase-space finite elements capability has been built into the Sceptre code and applied to several test problems, including a simple one-dimensional problem with an analytic solution available, a two-dimensional problem with an isolated source term, showing how the method essentially eliminates ray effects encountered with discrete ordinates, and a simple one-dimensional charged-particle transport problem in the presence of an electric field. (authors)
Phased Array-Fed Reflector (PAFR) Antenna Architectures for Space-Based Sensors
NASA Technical Reports Server (NTRS)
Cooley, Michael E.
2014-01-01
Communication link and target ranges for satellite communications (SATCOM) and space-based sensors (e.g. radars) vary from approximately 1000 km (for LEO satellites) to 35,800 km (for GEO satellites). At these long ranges, large antenna gains are required and legacy payloads have usually employed large reflectors with single beams that are either fixed or mechanically steered. For many applications, there are inherent limitations that are associated with the use of these legacy antennas/payloads. Hybrid antenna designs using Phased Array Fed Reflectors (PAFRs) provide a compromise between reflectors and Direct Radiating phased Arrays (DRAs). PAFRs provide many of the performance benefits of DRAs while utilizing much smaller, lower cost (feed) arrays. The primary limitation associated with hybrid PAFR architectures is electronic scan range; approximately +/-5 to +/- 10 degrees is typical, but this range depends on many factors. For LEO applications, the earth FOV is approximately +/-55 degrees which is well beyond the range of electronic scanning for PAFRs. However, for some LEO missions, limited scanning is sufficient or the CONOPS and space vehicle designs can be developed to incorporate a combination mechanical slewing and electronic scanning. In this paper, we review, compare and contrast various PAFR architectures with a focus on their general applicability to space missions. We compare the RF performance of various PAFR architectures and describe key hardware design and implementation trades. Space-based PAFR designs are highly multi-disciplinary and we briefly address key hardware engineering design areas. Finally, we briefly describe two PAFR antenna architectures that have been developed at Northrop Grumman.
Some non-linear interactions in polytropic gas cosmology: phase space analysis
NASA Astrophysics Data System (ADS)
Khurshudyan, Martiros
2015-11-01
There are various cosmological models with polytropic equation of state associated to dark energy. Polytropic EoS has important applications in astrophysics, therefore a study of it on cosmological framework continues to be interesting. From the other hand, there are various forms of interactions phenomenologically involved into the darkness of the universe able to solve important cosmological problems. This is a motivation for us to perform a phase space analysis of various cosmological scenarios where non-linear interacting polytropic gas models are involved. Dark matter is taken to be a pressureless fluid.
Canonical deformations of surfaces of equilibrium states in thermodynamic phase space
Jurkowski
2000-08-01
Deformations of submanifolds of thermodynamic equilibrium states introduced by continuous contact maps on a phase-space manifold are considered in terms of the geometrical formulation of thermodynamics. The notion of a contact Hamiltonian is recalled in order to give some possible physical interpretations of such a function in terms of statistical quantities describing initial and deformed systems. Using contact flows we propose a very efficient method for constructing continuous families of thermodynamic systems. A few examples show the possible advantages of using contact Hamiltonians. PMID:11088641
On a phase space quantum description of the spherical 2-brane
NASA Astrophysics Data System (ADS)
Cordero, R.; Turrubiates, F. J.; Vera, J. C.
2014-07-01
The quantum properties of the two-dimensional relativistic spherical membrane in phase space are analyzed using the Wigner function. Specifically, the true vacuum and rigid bubble nucleation cases are treated. Inspired by quantum cosmology, the Hartle-Hawking, Linde and Vilenkin boundary conditions are employed to calculate the bubble wave functions and their corresponding Wigner functions. Furthermore, the asymptotic behavior of the wave function using three different methods is explored and the Wigner functions are calculated numerically. Some aspects of the semiclassical properties for each boundary condition and their possible implications for quantum cosmology are discussed.
NASA Astrophysics Data System (ADS)
Shu, X. F.; Liu, S. B.; Song, H. Y.
2016-04-01
In this paper, the ionization processes during laser-atom interaction are investigated in phase-space using Gabor transformation. Based on the time-dependent Schrödinger equation (TDSE), the depletion of the whole system caused by the mask function is taken into consideration in calculating the plasma density. We obtain the momentum distribution via the Gabor transformation of the escaping portions of the time-dependent wave packet at the detector-like points on the interior boundaries from which the kinetic energies carried by the escaping portions are calculated.
Spinor Field at the Phase Transition Point of Reissner-Nordström de Sitter Space
NASA Astrophysics Data System (ADS)
Lyu, Yan; Zhang, Li-Qing; Zheng, Wei; Pan, Qing-Chao
2010-08-01
The radial parts of Dirac equation between the outer black hole horizon and the cosmological horizon are solved in Reissner-Nordström de Sitter (RNdS) space when it is at the phase transition point. We use an accurate polynomial approximation to approximate the modified tortoise coordinate hat{r}_{*} in order to get the inverse function r=r(hat{r}_{*}) and the potential V(hat{r}_{*}). Then we use a quantum mechanical method to solve the wave equation numerically. We consider two cases, one is when the two horizons are lying close to each other, the other is when the two horizons are widely separated.
Schach Von Wittenau, Alexis E.
2003-01-01
A method is provided to represent the calculated phase space of photons emanating from medical accelerators used in photon teletherapy. The method reproduces the energy distributions and trajectories of the photons originating in the bremsstrahlung target and of photons scattered by components within the accelerator head. The method reproduces the energy and directional information from sources up to several centimeters in radial extent, so it is expected to generalize well to accelerators made by different manufacturers. The method is computationally both fast and efficient overall sampling efficiency of 80% or higher for most field sizes. The computational cost is independent of the number of beams used in the treatment plan.
Capture into resonance and phase-space dynamics in an optical centrifuge
NASA Astrophysics Data System (ADS)
Armon, Tsafrir; Friedland, Lazar
2016-04-01
The process of capture of a molecular ensemble into rotational resonance in the optical centrifuge is investigated. The adiabaticity and phase-space incompressibility are used to find the resonant capture probability in terms of two dimensionless parameters P1 ,2 characterizing the driving strength and the nonlinearity, and related to three characteristic time scales in the problem. The analysis is based on the transformation to action-angle variables and the single resonance approximation, yielding reduction of the three-dimensional rotation problem to one degree of freedom. The analytic results for capture probability are in good agreement with simulations. The existing experiments satisfy the validity conditions of the theory.
Sun, Yin-e; Piot, Philippe; /Fermilab /Northern Illinois U.
2008-10-01
We demonstrate analytically and via numerical simulations, how a longitudinal-to-transverse phase space manipulation can be used to produce a train of femtosecond electron bunches. The technique uses an incoming transversely-modulated electron beam obtained via destructive (e.g. using a multislits mask) methods. A transverse-to-longitudinal exchanger is used to map this transverse modulation into a temporal modulation. Limitation of the proposed method and scalability to the femtosecond regime are analyzed analytically and with the help of numerical simulation. Finally, a proof-of-principle experiment is discussed in the context of the Fermilab's A0 photoinjector.
Brown, James Carrington, Tucker
2015-07-28
Although phase-space localized Gaussians are themselves poor basis functions, they can be used to effectively contract a discrete variable representation basis [A. Shimshovitz and D. J. Tannor, Phys. Rev. Lett. 109, 070402 (2012)]. This works despite the fact that elements of the Hamiltonian and overlap matrices labelled by discarded Gaussians are not small. By formulating the matrix problem as a regular (i.e., not a generalized) matrix eigenvalue problem, we show that it is possible to use an iterative eigensolver to compute vibrational energy levels in the Gaussian basis.
Brown, James; Carrington, Tucker
2015-07-28
Although phase-space localized Gaussians are themselves poor basis functions, they can be used to effectively contract a discrete variable representation basis [A. Shimshovitz and D. J. Tannor, Phys. Rev. Lett. 109, 070402 (2012)]. This works despite the fact that elements of the Hamiltonian and overlap matrices labelled by discarded Gaussians are not small. By formulating the matrix problem as a regular (i.e., not a generalized) matrix eigenvalue problem, we show that it is possible to use an iterative eigensolver to compute vibrational energy levels in the Gaussian basis. PMID:26233104
NASA Astrophysics Data System (ADS)
Brown, James; Carrington, Tucker
2015-07-01
Although phase-space localized Gaussians are themselves poor basis functions, they can be used to effectively contract a discrete variable representation basis [A. Shimshovitz and D. J. Tannor, Phys. Rev. Lett. 109, 070402 (2012)]. This works despite the fact that elements of the Hamiltonian and overlap matrices labelled by discarded Gaussians are not small. By formulating the matrix problem as a regular (i.e., not a generalized) matrix eigenvalue problem, we show that it is possible to use an iterative eigensolver to compute vibrational energy levels in the Gaussian basis.
Noether theorem for nonholonomic nonconservative mechanical systems in phase space on time scales
NASA Astrophysics Data System (ADS)
Zu, Qi-hang; Zhu, Jian-qing
2016-08-01
The paper focuses on studying the Noether theorem for nonholonomic nonconservative mechanical systems in phase space on time scales. First, the Hamilton equations of nonholonomic nonconservative systems on time scales are established, which is based on the Lagrange equations for nonholonomic systems on time scales. Then, based upon the quasi-invariance of Hamilton action of systems under the infinitesimal transformations with respect to the time and generalized coordinate on time scale, the Noether identity and the conserved quantity of nonholonomic nonconservative systems on time scales are obtained. Finally, an example is presented to illustrate the application of the results.
Poincaré inverse problem and torus construction in phase space
NASA Astrophysics Data System (ADS)
Laakso, Teemu; Kaasalainen, Mikko
2016-02-01
The phase space of an integrable Hamiltonian system is foliated by invariant tori. For an arbitrary Hamiltonian H such a foliation may not exist, but we can artificially construct one through a parameterised family of surfaces, with the intention of finding, in some sense, the closest integrable approximation to H. This is the Poincaré inverse problem (PIP). In this paper, we review the available methods of solving the PIP and present a new iterative approach which works well for the often problematic thin orbits.
Solid Phase Characterization of Tank 241-AY-102 Annulus Space Particulate
Cooke, G. A.
2013-01-30
The Special Analytical Studies Group at the 222-S Laboratory (222-S) examined the particulate recovered from a series of samples from the annular space of tank 241-AY-102 (AY-102) using solid phase characterization (SPC) methods. These include scanning electron microscopy (SEM) using the ASPEX®1 scanning electron microscope, X-ray diffraction (XRD) using the Rigaku®2 MiniFlex X-ray diffractometer, and polarized light microscopy (PLM) using the Nikon®3 Eclipse Pol optical microscope. The SEM is equipped with an energy dispersive X-ray spectrometer (EDS) to provide chemical information.
The Impact of Early Design Phase Risk Identification Biases on Space System Project Performance
NASA Technical Reports Server (NTRS)
Reeves, John D., Jr.; Eveleigh, Tim; Holzer, Thomas; Sarkani, Shahryar
2012-01-01
Risk identification during the early design phases of complex systems is commonly implemented but often fails to result in the identification of events and circumstances that truly challenge project performance. Inefficiencies in cost and schedule estimation are usually held accountable for cost and schedule overruns, but the true root cause is often the realization of programmatic risks. A deeper understanding of frequent risk identification trends and biases pervasive during space system design and development is needed, for it would lead to improved execution of existing identification processes and methods.
The impact of the phase-space density on the indirect detection of dark matter
Ferrer, Francesc; Hunter, Daniel R.
2013-09-01
We study the indirect detection of dark matter when the local dark matter velocity distribution depends upon position, as expected for the Milky Way and its dwarf spheroidal satellites, and the annihilation cross-section is not purely s-wave. Using a phase-space distribution consistent with the dark matter density profile, we present estimates of cosmic and gamma-ray fluxes from dark matter annihilations. The expectations for the indirect detection of dark matter can differ significantly from the usual calculation that assumes that the velocity of the dark matter particles follows a Maxwell-Boltzmann distribution.
Working fluid selection for space-based two-phase heat transport systems
NASA Technical Reports Server (NTRS)
Mclinden, Mark O.
1988-01-01
The working fluid for externally-mounted, space-based two-phase heat transport systems is considered. A sequence of screening criteria involving freezing and critical point temperatures and latent heat of vaporization and vapor density are applied to a data base of 860 fluids. The thermal performance of the 52 fluids which pass this preliminary screening are then ranked according to their impact on the weight of a reference system. Upon considering other nonthermal criteria (flammability, toxicity, and chemical stability) a final set of 10 preferred fluids is obtained. The effects of variations in system parameters is investigated for these 10 fluids by means of a factorial design.
Phase-space analysis of charged and optical beam transport: Wigner rotation angle
NASA Technical Reports Server (NTRS)
Dattoli, G.; Torre, Amalia
1994-01-01
The possibility of using the phase space formalism to establish a correspondence between the dynamical behavior of squeezed states and optical or charged beams, propagating through linear systems, has received a great deal of attention during the last years. In this connection, it has been indicated how optical experiments may be conceived to measure the Wigner rotation angle. In this paper we address the topic within the context of the paraxial propagation of optical or charged beams and suggest a possible experiment for measuring the Wigner angle using an electron beam passing through quadrupoles and drift sections. The analogous optical system is also discussed.
Hubble Space Telescope cycle 5. Phase 1: Proposal instructions, version 4.0
NASA Technical Reports Server (NTRS)
Madau, Piero (Editor)
1994-01-01
This document has the following purposes: it describes the information that must be submitted to the Space Telescope Science Institute by Phase 1 proposers, both electronically and on paper, and describes how to submit it; it describes how to fill out the proposal LATEX templates; it describes how to estimate the number of spacecraft orbits that the proposed observations will require; it provides detailed information about the parameters that are used in the forms to describe the requested observations; and it provides information about the preparation and electronic submission of proposal files. Examples of completed proposal forms are included.
Mendoza-Hernández, J.; Arroyo Carrasco, M.L.; Méndez Otero, M.M.; Chávez-Cerda, S.; Iturbe Castillo, M.D.
2014-01-01
In this paper, we demonstrate, numerically and experimentally that using the mask-lens setup used by Durnin to generate Bessel beams Durnin [Phys. Rev. Lett. 58, 1499 (1987)], it is possible to generate different kinds of propagation invariant beams. A modification in the amplitude or phase of the field that illuminates the annular slit is proposed that corresponds to modulation in frequency space. In particular, we characterize the new invariant beams that were obtained by modulating the amplitude of the annular mask and when the incident field was modulated with a one-dimensional quadratic or cubic phase. Experimental results using an amplitude mask are shown in order to corroborate the numerical predictions. PMID:25705088
Fabrication of microchannels by space-selective control of phase separation in glass.
Yu, Yongze; Chen, Yeqin; Chen, Jiejie; Lv, Shichao; Feng, Xu; Qi, Yuzhong; Qiu, Jianrong; Zhou, Shifeng
2016-07-15
Microchannels have important scientific applications in many fields, because they enable precise control, manipulation, and analysis of fluid on a micrometer scale. Herein, we demonstrate an effective strategy for fabrication of microchannels, based on the space-selective phase separation in glass induced by a femtosecond laser. The proposed method shows its abilities in fabrication of three-dimensional microchannels with ∼5 mm length scale and a uniform cross section. Moreover, we also achieve the modulation of the morphology on the inner surface of microchannels by using objective lenses with various numerical-apertures. The physical mechanism of the phase separation and microstructure evolution is discussed. Our method provides new opportunities to fabricate microchannels with complex structures and multifunctional integration. PMID:27420538
Demonstration of extended capture range for James Webb Space Telescope phase retrieval.
Carlisle, R Elizabeth; Acton, D Scott
2015-07-20
A geometrical phase retrieval (GPR) algorithm is applied to the problem of image stacking in order to extend the capture range of normal phase retrieval (PR) on the James Webb Space Telescope (JWST), and potentially eliminate a lengthy image-stacking process that is based on centroids. Computer simulations are used to establish the capture range of the existing PR algorithm for JWST and demonstrate that it is increased by more than a factor of 10 when combined with GPR, guaranteeing PR capture 95% of the time. An experiment using a scale optical model of JWST was conducted to demonstrate the effectiveness of the GPR algorithm in both coherent and incoherent imaging. PMID:26367828
Metallic phase of the quantum Hall effect in four-dimensional space
NASA Astrophysics Data System (ADS)
Edge, Jonathan; Tworzydlo, Jakub; Beenakker, Carlo
2013-03-01
We study the phase diagram of the quantum Hall effect in four-dimensional (4D) space. Unlike in 2D, in 4D there exists a metallic as well as an insulating phase, depending on the disorder strength. The critical exponent ν ~ 1 . 2 of the diverging localization length at the quantum Hall insulator-to-metal transition differs from the semiclassical value ν = 1 of 4D Anderson transitions in the presence of time-reversal symmetry. Our numerical analysis is based on a mapping of the 4D Hamiltonian onto a 1D dynamical system, providing a route towards the experimental realization of the 4D quantum Hall effect. NanoCTM, FOM/NWO, ERC
NASA Astrophysics Data System (ADS)
Gupta, Beena R.; Kumar, Vinay
In this paper, we have considered Time-Frequency Analysis (TFA) and Poincaré Surface of Section (PSS) for the study of the phase space structure of nonlinear dynamical system. We have examined a sample of orbits taken in the framework of Circular Restricted Three-Body Problem (CRTBP). We have computed ridge-plots (i.e. time-frequency landscape) using the phase of the continuous wavelet transform. Clear visualization of resonance trappings and the transitions is an important feature of this method, which is presented using ridge-plots. The identification between periodic and quasi-periodic, chaotic sticky and nonsticky and regular and chaotic orbits are done in comparatively less time and with less computational effort. The spatial case of Circular Restricted Three-Body problem is considered to show the strength of Time-Frequency Analysis to higher dimensional systems. Also, with the help of ridge-plots, we can visualize the phenomenon of transient chaos.
Polymorphic phase transitions in systems evolving in a two-dimensional discrete space.
Gadomski, A
1999-08-01
Polymorphic phase transitions in systems evolving in a two-dimensional discrete space have been studied. The driving force of the transitions appears to be a difference between two main energetic contributions: one, related to the thermal activation of the process, and another, being of quantum nature. The former (high temperature limit) is naturally assigned to the expansion (melting) part of the transition, while the latter (low temperature limit) has much in common with the contraction (solidification) part. Between the two main physical states distinguished, there exists a certain state, corresponding to a discontinuity point (pole) in the morphological phase diagram, represented by the well-known Bose-Einstein (Planck) formula, in which the system blows up. This point is related to an expected situation in which the contour of the object under investigation stands for the Brownian or purely diffusional path, with the fractal dimension dw=2, and the situation can be interpreted as some emergence of an intermediate "tetratic" phase. This, in turn, recalls a certain analogy to the equilibrium (order-disorder) phase transition of Kosterlitz-Thouless type, characteristic of, e.g., rough vs rigid interfaces in a two-dimensional space, with some disappearance of interface correlation length at dw=2. Otherwise, the contours of the objects are equivalent to fractional Brownian paths either in superlinear or "turbulent" (dw<2; the expansion case), or sublinear, viz., anomalously slow (dw>2; the contraction case) regimes, respectively. It is hoped that the description offered will serve to reflect properly the main subtleties of the dynamics of the polymorphic transitions in complex "soft-matter" systems, like formation of lipid mesomorphs or diffusional patterns, with nonzero line tension effect. PMID:11969883
James Webb Space Telescope segment phasing using differential optical transfer functions
Codona, Johanan L.; Doble, Nathan
2015-01-01
Differential optical transfer function (dOTF) is an image-based, noniterative wavefront sensing method that uses two star images with a single small change in the pupil. We describe two possible methods for introducing the required pupil modification to the James Webb Space Telescope, one using a small (<λ/4) displacement of a single segment's actuator and another that uses small misalignments of the NIRCam's filter wheel. While both methods should work with NIRCam, the actuator method will allow both MIRI and NIRISS to be used for segment phasing, which is a new functionality. Since the actuator method requires only small displacements, it should provide a fast and safe phasing alternative that reduces the mission risk and can be performed frequently for alignment monitoring and maintenance. Since a single actuator modification can be seen by all three cameras, it should be possible to calibrate the non-common-path aberrations between them. Large segment discontinuities can be measured using dOTFs in two filter bands. Using two images of a star field, aberrations along multiple lines of sight through the telescope can be measured simultaneously. Also, since dOTF gives the pupil field amplitude as well as the phase, it could provide a first approximation or constraint to the planned iterative phase retrieval algorithms. PMID:27042684
James Webb Space Telescope segment phasing using differential optical transfer functions
NASA Astrophysics Data System (ADS)
Codona, Johanan L.; Doble, Nathan
2015-04-01
Differential optical transfer function (dOTF) is an image-based, noniterative wavefront sensing method that uses two star images with a single small change in the pupil. We describe two possible methods for introducing the required pupil modification to the James Webb Space Telescope, one using a small (<λ/4) displacement of a single segment's actuator and another that uses small misalignments of the NIRCam's filter wheel. While both methods should work with NIRCam, the actuator method will allow both MIRI and NIRISS to be used for segment phasing, which is a new functionality. Since the actuator method requires only small displacements, it should provide a fast and safe phasing alternative that reduces the mission risk and can be performed frequently for alignment monitoring and maintenance. Since a single actuator modification can be seen by all three cameras, it should be possible to calibrate the non-common-path aberrations between them. Large segment discontinuities can be measured using dOTFs in two filter bands. Using two images of a star field, aberrations along multiple lines of sight through the telescope can be measured simultaneously. Also, since dOTF gives the pupil field amplitude as well as the phase, it could provide a first approximation or constraint to the planned iterative phase retrieval algorithms.
Paz, Juan Pablo; Roncaglia, Augusto Jose; Saraceno, Marcos
2005-07-15
We analyze and further develop a method to represent the quantum state of a system of n qubits in a phase-space grid of NxN points (where N=2{sup n}). The method, which was recently proposed by Wootters and co-workers (Gibbons et al., Phys. Rev. A 70, 062101 (2004).), is based on the use of the elements of the finite field GF(2{sup n}) to label the phase-space axes. We present a self-contained overview of the method, we give insights into some of its features, and we apply it to investigate problems which are of interest for quantum-information theory: We analyze the phase-space representation of stabilizer states and quantum error-correction codes and present a phase-space solution to the so-called mean king problem.
Gravitational collapse of a homogeneous scalar field in deformed phase space
NASA Astrophysics Data System (ADS)
Rasouli, S. M. M.; Ziaie, A. H.; Marto, J.; Moniz, P. V.
2014-02-01
We study the gravitational collapse of a homogeneous scalar field, minimally coupled to gravity, in the presence of a particular type of dynamical deformation between the canonical momenta of the scale factor and of the scalar field. In the absence of such a deformation, a class of solutions can be found in the literature [R. Goswami and P. S. Joshi], whereby a curvature singularity occurs at the collapse end state, which can be either hidden behind a horizon or be visible to external observers. However, when the phase space is deformed, as implemented herein this paper, we find that the singularity may be either removed or instead, attained faster. More precisely, for negative values of the deformation parameter, we identify the emergence of a negative pressure term, which slows down the collapse so that the singularity is replaced with a bounce. In this respect, the formation of a dynamical horizon can be avoided depending on the suitable choice of the boundary surface of the star. Whereas for positive values, the pressure that originates from the deformation effects assists the collapse toward the singularity formation. In this case, since the collapse speed is unbounded, the condition on the horizon formation is always satisfied and furthermore the dynamical horizon develops earlier than when the phase-space deformations are absent. These results are obtained by means of a thoroughly numerical discussion.
Radiation from Electron Phase Space Holes as a Possible Source of Jovian S-bursts
NASA Astrophysics Data System (ADS)
Goodrich, Katherine; Ergun, Robert; Holmes, Justin
2016-04-01
Radio-frequency short burst emissions (10-40 MHz), known as Jovian S-bursts, have been observed from the Jovian aurora for over fifty years. These emissions, associated with Io's motion, have a rapidly declining frequency and an exceptionally narrow bandwidth. While it is widely believed that S-bursts are generated by the electron cyclotron maser instability, the mechanism responsible for the rapidly declining frequency and narrow bandwidth currently is not well established. We explore a hypothesis that electron phase space holes radiate or stimulate radiation in the Jovian aurora plasma environment as a possible source of S-burst emissions. Electron phase-space holes (EHs) are ubiquitous in an auroral environment and travel at the implied speeds (˜20,000 km/s) of the structures creating the Jovian S-bursts. Furthermore, EHs have the proper physical size to create the observed bandwidth, have sufficient energy content, and can create an environment whereby X mode emissions can be excited. If verified, these findings imply that EHs may be an important source of radiation from strongly magnetized or relativistic astrophysical plasmas.
A phase-space approach for propagating field-field correlation functions
NASA Astrophysics Data System (ADS)
Gradoni, Gabriele; Creagh, Stephen C.; Tanner, Gregor; Smartt, Christopher; Thomas, David W. P.
2015-09-01
We show that radiation from complex and inherently random but correlated wave sources can be modelled efficiently by using an approach based on the Wigner distribution function. Our method exploits the connection between correlation functions and the Wigner function and admits in its simplest approximation a direct representation in terms of the evolution of ray densities in phase space. We show that next leading order corrections to the ray-tracing approximation lead to Airy-function type phase space propagators. By exploiting the exact Wigner function propagator, inherently wave-like effects such as evanescent decay or radiation from more heterogeneous sources as well as diffraction and reflection can be included and analysed. We discuss in particular the role of evanescent waves in the near-field of non-paraxial sources and give explicit expressions for the growth rate of the correlation length as a function of the distance from the source. The approximations are validated using full-wave simulations of model sources. In particular, results for the reflection of partially coherent sources from flat mirrors are given where the influence of Airy function corrections can be demonstrated. We focus here on electromagnetic sources at microwave frequencies and modelling efforts in the context of electromagnetic compatibility.
de Almeida, V.F.
2004-01-28
A phase-space discontinuous Galerkin (PSDG) method is presented for the solution of stellar radiative transfer problems. It allows for greater adaptivity than competing methods without sacrificing generality. The method is extensively tested on a spherically symmetric, static, inverse-power-law scattering atmosphere. Results for different sizes of atmospheres and intensities of scattering agreed with asymptotic values. The exponentially decaying behavior of the radiative field in the diffusive-transparent transition region and the forward peaking behavior at the surface of extended atmospheres were accurately captured. The integrodifferential equation of radiation transfer is solved iteratively by alternating between the radiative pressure equation and the original equation with the integral term treated as an energy density source term. In each iteration, the equations are solved via an explicit, flux-conserving, discontinuous Galerkin method. Finite elements are ordered in wave fronts perpendicularly to the characteristic curves so that elemental linear algebraic systems are solved quickly by sweeping the phase space element by element. Two implementations of a diffusive boundary condition at the origin are demonstrated wherein the finite discontinuity in the radiative intensity is accurately captured by the proposed method. This allows for a consistent mechanism to preserve photon luminosity. The method was proved to be robust and fast, and a case is made for the adequacy of parallel processing. In addition to classical two-dimensional plots, results of normalized radiative intensity were mapped onto a log-polar surface exhibiting all distinguishing features of the problem studied.
NASA Astrophysics Data System (ADS)
Chauhan, V.; Ragnarsson, Á.
2015-12-01
The present work discusses the utilization of phase change materials for energy storage in geothermal space heating systems. Thermodynamics and thermoeconomics of the combined heating and thermal storing system were studied to show the scope of energy storage and cost savings. A computational model of the combined space heating and thermal storage system was developed and used to perform thermodynamic studies of the heat storage process and heating system efficiency at different times and ambient temperatures. The basis for these studies is daily variations in heating demand that is higher during the night than during the day. The results show the scope of the utilization of phase change material for low ambient temperature conditions. Under proper conditions a sufficient amount of exergy is stored during the charging period at a low ambient temperature to fulfill the daytime heat load requirement. Under these conditions the cost flow rate of exergy storage is found to be lower than the radiator heating cost flow rate. Thus, the use of exergy storage at low ambient temperatures for heating at higher ambient temperatures makes a significant contribution to cost savings.
Use of Projectional Phase Space Data to Infer a 4D Particle Distribution
Friedman, A; Grote, D P; Celata, C M; Staples, J W
2002-05-15
We consider beams which are described by a 4D transverse distribution f(x, y, x', y'), where x' {triple_bond} p{sub x}/p{sub z} and z is the axial coordinate. A two-slit scanner is commonly employed to measure, over a sequence of shots, a 2D projection of such a beam's phase space, e.g., f(x, x'). Another scanner might yield f(y, y') or, using crossed slits, f(x, y). A small set of such 2D scans does not uniquely specify f(x, y, x', y'). We have developed ''tomographic'' techniques to synthesize a ''reasonable'' set of particles in a 4D phase space having 2D densities consistent with the experimental data. These techniques are described in a separate document [A. Friedman, et. al., submitted to Phys. Rev. ST-AB, 2002]. Here we briefly summarize one method and describe progress in validating it, using simulations of the High Current Experiment at Lawrence Berkeley National Laboratory.
NASA Astrophysics Data System (ADS)
Su, Zhi-Yuan; Wu, Tzuyin; Yang, Po-Hua; Wang, Yeng-Tseng
2008-04-01
The heartbeat rate signal provides an invaluable means of assessing the sympathetic-parasympathetic balance of the human autonomic nervous system and thus represents an ideal diagnostic mechanism for detecting a variety of disorders such as epilepsy, cardiac disease and so forth. The current study analyses the dynamics of the heartbeat rate signal of known epilepsy sufferers in order to obtain a detailed understanding of the heart rate pattern during a seizure event. In the proposed approach, the ECG signals are converted into heartbeat rate signals and the embedology theorem is then used to construct the corresponding multidimensional phase space. The dynamics of the heartbeat rate signal are then analyzed before, during and after an epileptic seizure by examining the maximum Lyapunov exponent and the correlation dimension of the attractors in the reconstructed phase space. In general, the results reveal that the heartbeat rate signal transits from an aperiodic, highly-complex behaviour before an epileptic seizure to a low dimensional chaotic motion during the seizure event. Following the seizure, the signal trajectories return to a highly-complex state, and the complex signal patterns associated with normal physiological conditions reappear.
Space shuttle phase B wind tunnel model and test information. Volume 3: Launch configuration
NASA Technical Reports Server (NTRS)
Glynn, J. L.; Poucher, D. E.
1988-01-01
Archived wind tunnel test data are available for flyback booster or other alternate recoverable configuration as well as reusable orbiters studied during initial development (Phase B) of the Space Shuttle, including contractor data for an extensive variety of configurations with an array of wing and body planforms. The test data have been compiled into a database and are available for application to current winged flyback or recoverable booster aerodynamic studies. The Space Shuttle Phase B Wind Tunnel Database is structured by vehicle component and configuration. Basic components include booster, orbiter, and launch vehicle. Booster configuration types include straight and delta wings, canard, cylindrical, retroglide and twin body. Orbiter configurations include straight and delta wings, lifting body, drop tanks and double delta wings. Launch configurations include booster and orbiter components in various stacked and tandem combinations. The digital database consists of 220 files containing basic tunnel data. Database structure is documented in a series of reports which include configuration sketches for the various planforms tested. This is Volume 3 -- launch configurations.
Energetic particle phase space densities at Saturn: Cassini observations and interpretations
NASA Astrophysics Data System (ADS)
Kollmann, P.; Roussos, E.; Paranicas, C.; Krupp, N.; Jackman, C. M.; Kirsch, E.; Glassmeier, K.-H.
2011-05-01
Saturn's magnetosphere has been studied extensively by the Cassini spacecraft during the last 6 years. We present mission-averaged energetic proton and electron measurements obtained by the MIMI/LEMMS instrument onboard Cassini in an energy range from several 10 keV to several 10 MeV separated by equatorial pitch angle. We discuss the resulting radial profiles and energy spectra. The measured intensities are converted to phase space densities. The distribution of energetic particles is governed by a large variety of processes. For instance, moons absorb energetic particles, creating macrosignatures or microsignatures. We have found that the moon Rhea is partly responsible for a change in gradient of electron phase space densities. We show that, in contrast to larger distances, the particle distribution for L < 8 is not driven by radial diffusion alone. There, the particle profiles are significantly modified due to Saturn's Neutral Torus, plasma environment, E ring, injection events, and cosmic ray albedo neutron decay. Large parts of our analysis are focused near L = 7. There, protons are lost within the Neutral Torus and not the E ring. For electrons, we find that these two losses are of comparable rate but have discovered that neither process is the dominant driver of loss. We point out that intensity measured by a energy channel, such as in a particle instrument, can actually increase in the region of ring and torus instead of decrease. The importance of injection events is shown to be at least of similar importance as radial diffusion.
The Phase Space Structure Near Neptune Resonances in the Kuiper Belt
NASA Technical Reports Server (NTRS)
Malhotra, Renu
1996-01-01
The Solar system beyond Neptune is believed to house a population of small primordial bodies left over from the planet formation process. The region up to heliocentric distance -50 AU (a.k.a. the Kuiper Belt) may be the source of the observed short-period comets. In this region, the phase space structure near orbital resonances with Neptune is of special interest for the long-term stability of orbits. There is reason to believe that a significant fraction (perhaps most) of the Kuiper Belt objects reside preferentially in these resonance locations. This paper describes the dynamics of small objects near the major orbital resonances with Neptune. Estimates of the widths of stable resonance zones as well as the properties of resonant orbits are obtained from the circular, planar restricted three-body model. Although this model does not contain the full complexity of the long-term orbital dynamics of Kuiper Belt objects subject to the full N-body perturbations of all the planets, it does provide a baseline for the phase space structure and properties of resonant orbits in the trans-Neptunian Solar system.
EEMD Independent Extraction for Mixing Features of Rotating Machinery Reconstructed in Phase Space
Ma, Zaichao; Wen, Guangrui; Jiang, Cheng
2015-01-01
Empirical Mode Decomposition (EMD), due to its adaptive decomposition property for the non-linear and non-stationary signals, has been widely used in vibration analyses for rotating machinery. However, EMD suffers from mode mixing, which is difficult to extract features independently. Although the improved EMD, well known as the ensemble EMD (EEMD), has been proposed, mode mixing is alleviated only to a certain degree. Moreover, EEMD needs to determine the amplitude of added noise. In this paper, we propose Phase Space Ensemble Empirical Mode Decomposition (PSEEMD) integrating Phase Space Reconstruction (PSR) and Manifold Learning (ML) for modifying EEMD. We also provide the principle and detailed procedure of PSEEMD, and the analyses on a simulation signal and an actual vibration signal derived from a rubbing rotor are performed. The results show that PSEEMD is more efficient and convenient than EEMD in extracting the mixing features from the investigated signal and in optimizing the amplitude of the necessary added noise. Additionally PSEEMD can extract the weak features interfered with a certain amount of noise. PMID:25871723
Evolution of Phase Space Sensitivity for Energetic Ion Loss Measurements in DIII-D
NASA Astrophysics Data System (ADS)
Cothard, N.; Pace, D. C.
2014-10-01
The Fast Ion Loss Detector (FILD) diagnostic system installed on the DIII-D tokamak is a scintillator-based magnetic spectrometer that measures the energy and pitch angle of energetic ions that escape confinement and reach the diagnostic on the outer wall. Different areas of the FILD scintillator correspond to the energies and pitch angles of the impacting ions. This strike map is dependent on the local magnetic field vector that sets the geometry of the ion orbits upon entering the detector. The phase space sensitivity of the FILD, therefore, varies with plasma conditions. The FILD combines a slow camera (100 Hz) viewing the entire scintillator simultaneously with narrow viewing photomultiplier tubes that provide fast time-resolved (1MHz) measurements in narrow bands of energy and pitch angle. New analysis methods allow for tracking the phase space coverage throughout shots, thereby improving the fidelity of ion loss measurements due to plasma instabilities that change in time. Work supported in part by the National Undergraduate Fellowship Program in Plasma Physics and Fusion Energy Sciences and the US Department of Energy under DE-FC02-04ER54698.
Entropy Production in Collisionless Systems. II. Arbitrary Phase-space Occupation Numbers
NASA Astrophysics Data System (ADS)
Barnes, Eric I.; Williams, Liliya L. R.
2012-04-01
We present an analysis of two thermodynamic techniques for determining equilibria of self-gravitating systems. One is the Lynden-Bell (LB) entropy maximization analysis that introduced violent relaxation. Since we do not use the Stirling approximation, which is invalid at small occupation numbers, our systems have finite mass, unlike LB's isothermal spheres. (Instead of Stirling, we utilize a very accurate smooth approximation for ln x!.) The second analysis extends entropy production extremization to self-gravitating systems, also without the use of the Stirling approximation. In addition to the LB statistical family characterized by the exclusion principle in phase space, and designed to treat collisionless systems, we also apply the two approaches to the Maxwell-Boltzmann (MB) families, which have no exclusion principle and hence represent collisional systems. We implicitly assume that all of the phase space is equally accessible. We derive entropy production expressions for both families and give the extremum conditions for entropy production. Surprisingly, our analysis indicates that extremizing entropy production rate results in systems that have maximum entropy, in both LB and MB statistics. In other words, both thermodynamic approaches lead to the same equilibrium structures.
ENTROPY PRODUCTION IN COLLISIONLESS SYSTEMS. II. ARBITRARY PHASE-SPACE OCCUPATION NUMBERS
Barnes, Eric I.; Williams, Liliya L. R. E-mail: llrw@astro.umn.edu
2012-04-01
We present an analysis of two thermodynamic techniques for determining equilibria of self-gravitating systems. One is the Lynden-Bell (LB) entropy maximization analysis that introduced violent relaxation. Since we do not use the Stirling approximation, which is invalid at small occupation numbers, our systems have finite mass, unlike LB's isothermal spheres. (Instead of Stirling, we utilize a very accurate smooth approximation for ln x{exclamation_point}.) The second analysis extends entropy production extremization to self-gravitating systems, also without the use of the Stirling approximation. In addition to the LB statistical family characterized by the exclusion principle in phase space, and designed to treat collisionless systems, we also apply the two approaches to the Maxwell-Boltzmann (MB) families, which have no exclusion principle and hence represent collisional systems. We implicitly assume that all of the phase space is equally accessible. We derive entropy production expressions for both families and give the extremum conditions for entropy production. Surprisingly, our analysis indicates that extremizing entropy production rate results in systems that have maximum entropy, in both LB and MB statistics. In other words, both thermodynamic approaches lead to the same equilibrium structures.
On the Existence of Our Metals-Based Civilization: I. Phase Space Analysis
D.D. Macdonald
2005-06-22
The stability of the barrier layers of bilayer passive films that form on metal and alloy surfaces, when in contact with oxidizing aqueous environments, is explored within the framework of the Point Defect Model (PDM) using phase-space analysis (PSA), in which the rate of growth of the barrier layer into the metal, (dL{sup +}/dt), and the barrier layer dissolution rate, (dL{sup -}/dt), are plotted simultaneously against the barrier layer thickness. A point of intersection of dL{sup -}/dt with dL{sup +}/dt indicates the existence of a metastable barrier layer with a steady state thickness greater than zero. If dL{sup -}/dt > (dL{sup +}/dt){sub L=0}, where the latter quantity is the barrier layer growth rate at zero barrier layer thickness, the barrier layer cannot exist, even as a metastable phase, as the resulting thickness would be negative. Under these conditions, the surface is depassivated and the metal may corrode at a rapid rate. Depassivation may result from a change in the oxidation state of the cation upon dissolution of the barrier layer, such that the dissolution rate becomes highly potential dependent (as in the case of transpassive dissolution of chromium-containing alloys, for example, in which the reaction Cr{sub 2}O{sub 3} + 5H{sub 2}O {yields} 2CrO{sub 4}{sup 2-} + 10H {sup +} + 6e{sup -} results in the destruction of the film), or by the action of some solution-phase species (e.g., H{sup +}, Cl{sup -}) that enhances the dissolution rate to the extent that dL{sup -}/dt > (dL{sup +}/dt){sub L=0}. The boundaries for depassivation may be plotted in potential-pH space to develop Kinetic Stability Diagrams (KSDs) as alternatives to the classical Pourbaix diagrams for describing the conditions under which metals or alloys exist in contact with an aqueous environment. The advantage of KSDs is that they provide kinetic descriptions of the state of a metal or alloy that is in much closer concert with the kinetic phenomenon of passivity and depassivation
Encoding Curved Tetrahedra in Face Holonomies: Phase Space of Shapes from Group-Valued Moment Maps
NASA Astrophysics Data System (ADS)
Haggard, Hal M.; Han, Muxin; Riello, Aldo
2016-08-01
We present a generalization of Minkowski's classic theorem on the reconstruction of tetrahedra from algebraic data to homogeneously curved spaces. Euclidean notions such as the normal vector to a face are replaced by Levi-Civita holonomies around each of the tetrahedron's faces. This allows the reconstruction of both spherical and hyperbolic tetrahedra within a unified framework. A new type of hyperbolic simplex is introduced in order for all the sectors encoded in the algebraic data to be covered. Generalizing the phase space of shapes associated to flat tetrahedra leads to group valued moment maps and quasi-Poisson spaces. These discrete geometries provide a natural arena for considering the quantization of gravity including a cosmological constant. A concrete realization of this is provided by the relation with the spin-network states of loop quantum gravity. This work therefore provides a bottom-up justification for the emergence of deformed gauge symmetries and quantum groups in 3+1 dimensional covariant loop quantum gravity in the presence of a cosmological constant.
A plan for time-phased incorporation of automation and robotics on the US space station
NASA Technical Reports Server (NTRS)
Purves, R. B.; Lin, P. S.; Fisher, E. M., Jr.
1988-01-01
A plan for the incorporation of Automation and Robotics technology on the Space Station is presented. The time phased introduction of twenty two selected candidates is set forth in accordance with a technology development forecast. Twenty candidates were chosed primarily for their potential to relieve the crew of mundane or dangerous operations and maintenance burdens, thus freeing crew time for mission duties and enhancing safety. Two candidates were chosen based on a potential for increasing the productivity of laboratory experiments and thus directly enhancing the scientific value of the Space Station. A technology assessment for each candidate investigates present state of the art, development timelines including space qualification considerations, and potential for technology transfer to earth applications. Each candidate is evaluated using a crew workload model driven by crew size, number of pressurized U.S. modules and external payloads, which makes it possible to assess the impact of automation during a growth scenario. Costs for each increment of implementation are estimated and accumulated.
On-orbit servicing for USAF space missions: A phased development approach
NASA Technical Reports Server (NTRS)
Shanney, Bill
1993-01-01
On-orbit servicing has been studied for years by the U.S. Air Force Space Systems Division--which recently cosponsored the Space Assembly, Maintenance, and Servicing Study with NASA and SDIO; but an Air force servicing program has yet to emerge. The Air Force has a limited set of servicing requirements, and the practices of 'pipelining' (incremental improvements to a space vehicle series) and orbital sparing provide many similar benefits. It is postulated that an Air Force Program will be initiated in response to a new critical mission requirement that calls for a spacecraft with the operational character of a Servicer, which will evolve into a servicing program. Such a requirement may be emerging. The Air Force organizations charged with on-orbit test safety for the Department of Defense are concerned with the hazard from uncontrolled reentry of low Earth orbit test spacecraft, which are increasing in number. Analysis and observations of actual reentries show that debris reaches the Earth's surface. A phased development of a system to remove these spacecraft from orbit can evolve into a servicing program.
NASA Astrophysics Data System (ADS)
Zavala, Jesús; Afshordi, Niayesh
2014-06-01
We present a model for the structure of the particle phase space average density (P2SAD) in galactic haloes, introduced recently as a novel measure of the clustering of dark matter. Our model is based on the stable clustering hypothesis in phase space, the spherical collapse model, and tidal disruption of substructures, which is calibrated against the Aquarius simulations. Using this model, we can predict the behaviour of P2SAD in the numerically unresolved regime, down to the decoupling mass limit of generic weakly interacting massive particle models. This prediction can be used to estimate signals sensitive to the small-scale structure of dark matter. For example, the dark matter annihilation rate can be estimated for arbitrary velocity-dependent cross-sections in a convenient way using a limit of P2SAD to zero separation in physical space. We illustrate our method by computing the global and local subhalo annihilation boost to that of the smooth dark matter distribution in a Milky Way-sized halo. Two cases are considered, one where the cross-section is velocity independent and one that approximates Sommerfeld-enhanced models. We find that the global boost is ˜10-30, which is at the low end of current estimates (weakening expectations of large extragalactic signals), while the boost at the solar radius is below the percent level. We make our code to compute P2SAD publicly available, which can be used to estimate various observables that probe the nanostructure of dark matter haloes.
Volume and Mass Estimation of Three-Phase High Power Transformers for Space Applications
NASA Technical Reports Server (NTRS)
Kimnach, Greg L.
2004-01-01
Spacecraft historically have had sub-1kW(sub e), electrical requirements for GN&C, science, and communications: Galileo at 600W(sub e), and Cassini at 900W(sub e), for example. Because most missions have had the same order of magnitude power requirements, the Power Distribution Systems (PDS) use existing, space-qualified technology and are DC. As science payload and mission duration requirements increase, however, the required electrical power increases. Subsequently, this requires a change from a passive energy conversion (solar arrays and batteries) to dynamic (alternator, solar dynamic, etc.), because dynamic conversion has higher thermal and conversion efficiencies, has higher power densities, and scales more readily to higher power levels. Furthermore, increased power requirements and physical distribution lengths are best served with high-voltage, multi-phase AC to maintain distribution efficiency and minimize voltage drops. The generated AC-voltage must be stepped-up (or down) to interface with various subsystems or electrical hardware. Part of the trade-space design for AC distribution systems is volume and mass estimation of high-power transformers. The volume and mass are functions of the power rating, operating frequency, the ambient and allowable temperature rise, the types and amount of heat transfer available, the core material and shape, the required flux density in a core, the maximum current density, etc. McLyman has tabulated the performance of a number of transformers cores and derived a "cookbook" methodology to determine the volume of transformers, whereas Schawrze had derived an empirical method to estimate the mass of single-phase transformers. Based on the work of McLyman and Schwarze, it is the intent herein to derive an empirical solution to the volume and mass estimation of three-phase, laminated EI-core power transformers, having radiated and conducted heat transfer mechanisms available. Estimation of the mounting hardware, connectors
Free-piston Stirling engine conceptual design and technologies for space power, phase 1
NASA Technical Reports Server (NTRS)
Penswick, L. Barry; Beale, William T.; Wood, J. Gary
1990-01-01
As part of the SP-100 program, a phase 1 effort to design a free-piston Stirling engine (FPSE) for a space dynamic power conversion system was completed. SP-100 is a combined DOD/DOE/NASA program to develop nuclear power for space. This work was completed in the initial phases of the SP-100 program prior to the power conversion concept selection for the Ground Engineering System (GES). Stirling engine technology development as a growth option for SP-100 is continuing after this phase 1 effort. Following a review of various engine concepts, a single-cylinder engine with a linear alternator was selected for the remainder of the study. The relationships of specific mass and efficiency versus temperature ratio were determined for a power output of 25 kWe. This parametric study was done for a temperature ratio range of 1.5 to 2.0 and for hot-end temperatures of 875 K and 1075 K. A conceptual design of a 1080 K FPSE with a linear alternator producing 25 kWe output was completed. This was a single-cylinder engine designed for a 62,000 hour life and a temperature ratio of 2.0. The heat transport systems were pumped liquid-metal loops on both the hot and cold ends. These specifications were selected to match the SP-100 power system designs that were being evaluated at that time. The hot end of the engine used both refractory and superalloy materials; the hot-end pressure vessel featured an insulated design that allowed use of the superalloy material. The design was supported by the hardware demonstration of two of the component concepts - the hydrodynamic gas bearing for the displacer and the dynamic balance system. The hydrodynamic gas bearing was demonstrated on a test rig. The dynamic balance system was tested on the 1 kW RE-1000 engine at NASA Lewis.
NASA Astrophysics Data System (ADS)
Zhang, Zhen-Hua; Song, Ren; Su, Yu-Mo; Lü, Gang; Zheng, Bo
2015-09-01
We perform a theoretical study on direct CP violation in in phase space around the intermediate states and . The possible interference between the amplitudes corresponding to the two resonances is taken into account, and the relative strong phase of the two amplitudes is treated as a free parameter. Our analysis shows that by a properly chosen strong phase, both the CP violation strength and the differential decay width accommodate the experimental results.
NASA Astrophysics Data System (ADS)
Wu, Jiandong; Huang, Ruodong; Wan, Jiadong; Chen, Yading; Yin, Yi; Chen, George
2016-04-01
Data processing (i.e. phase identification) using the instantaneous phase φ‧(t) defined by the Hilbert transform is discussed to confirm the detecting phase of the space charge observed by the pulsed electroacoustic method under the periodic wave V a (t). The discrete voltage V a (i) of the periodic wave at the detecting phase φ(i) is used for phase identification, and φ(i) is equally distributed to obtain N p divisions for the phase within one period. The accuracy of the discrete instantaneous phase φ‧(i) is significantly determined by the number of samples N for the discrete voltage V a (i). The instantaneous phase is consistent with the real phase of pure sine and cosine waves, and this phase linearly varies with time. However, the instantaneous phase non-linearly varies with time under the periodic stress of arbitrary waveforms. This limitation can be resolved using the base wave component, i.e. sine or cosine wave of V a (t), which is acquired by the Fourier transform. Finally, the space charge behaviour in low-density polyethylene under square and sine waves with offset is detected to verify the accuracy and effectiveness of the proposed method.
Exploring the phase space of multiple states in highly turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
van der Veen, Roeland; Huisman, Sander; Dung, On Yu; Tang, Ho Lun; Sun, Chao; Lohse, Detlef
2015-11-01
It was recently found that multiple turbulent states exist for large Reynolds number (Re =106) Taylor-Couette flow in the regime of ultimate turbulence. Here we investigate how the transitions between the multiple states depend on the Reynolds number in the range of Re =105 to 2 .106 , by measuring global torque and local velocity while probing the phase space spanned by the rotation rates of the inner and outer cylinder. This sheds light on the question whether multiple states persist for Reynolds numbers beyond those currently reached. By mapping the flow structures for various rotation ratios in two Taylor-Couette setups with equal radius ratio but different aspect ratio, we furthermore investigate the influence of aspect ratio on the characteristics of the multiple states.
Use of IAEA's phase-space files for virtual source model implementation: Extension to large fields.
Rucci, Alexis; Carletti, Claudia; Cravero, Walter; Strbac, Bojan
2016-08-01
In a previous work, phase-space data files (phsp) provided by the International Atomic Energy Agency (IAEA) were used to develop a hybrid virtual source model (VSM) for clinical photon beams. Very good agreement with dosimetric measurements performed on linear accelerators was obtained for field sizes up to 15×15cm(2). In the present work we extend the VSM to larger field sizes, for which phsp are not available. We incorporate a virtual flattening filter to our model, which can be determined from dose measurements for larger fields. In this way a fully functional VSM can be built, from publicly available IAEA's phsps and standard dose measurements, for fields of any size and tailored to a particular linac. PMID:27423827
Gray-molasses cooling of 39K to a high phase-space density
NASA Astrophysics Data System (ADS)
Salomon, G.; Fouché, L.; Wang, P.; Aspect, A.; Bouyer, P.; Bourdel, T.
2013-12-01
We present new techniques in cooling 39K atoms using laser light close to the D1 transition. First, a new compressed-MOT configuration is taking advantage of gray-molasses-type cooling induced by blue-detuned D1 light. It yields an optimized density of atoms. Then, we use pure D1 gray molasses to further cool the atoms to an ultra-low temperature of 6\\ \\mu\\text{K} . The resulting phase-space density is 2\\times 10^{-4} and will ease future experiments with ultracold potassium. As an example, we use it to directly load up to 3\\times 10^7 atoms in a far detuned optical trap, a result that opens the way to the all-optical production of potassium degenerate gases.
Spacecraft flight control with the new phase space control law and optimal linear jet select
NASA Technical Reports Server (NTRS)
Bergmann, E. V.; Croopnick, S. R.; Turkovich, J. J.; Work, C. C.
1977-01-01
An autopilot designed for rotation and translation control of a rigid spacecraft is described. The autopilot uses reaction control jets as control effectors and incorporates a six-dimensional phase space control law as well as a linear programming algorithm for jet selection. The interaction of the control law and jet selection was investigated and a recommended configuration proposed. By means of a simulation procedure the new autopilot was compared with an existing system and was found to be superior in terms of core memory, central processing unit time, firings, and propellant consumption. But it is thought that the cycle time required to perform the jet selection computations might render the new autopilot unsuitable for existing flight computer applications, without modifications. The new autopilot is capable of maintaining attitude control in the presence of a large number of jet failures.
Critical phenomena in the extended phase space of Kerr-Newman-AdS black holes
NASA Astrophysics Data System (ADS)
Cheng, Peng; Wei, Shao-Wen; Liu, Yu-Xiao
2016-07-01
Treating the cosmological constant as a thermodynamic pressure, we investigate the critical behavior of a Kerr-Newman-AdS black hole system. The critical points for the van der Waals like phase transition are numerically solved. The highly accurate fitting formula for them is given and is found to be dependent of the charge Q and angular momentum J . In the reduced parameter space, we find that the temperature, Gibbs free energy, and coexistence curve depend only on the dimensionless angular momentum-charge ratio ɛ =J /Q2 . Moreover, when varying ɛ from 0 to ∞ , the coexistence curve will continuously change from that of the Reissner-Nordström-AdS black hole to the Kerr-AdS black hole. These results may guide us to study the critical phenomena for other thermodynamic systems with two characteristic parameters.
NASA Astrophysics Data System (ADS)
Mancho, Ana M.; Wiggins, Stephen; Curbelo, Jezabel; Mendoza, Carolina
2013-11-01
Lagrangian descriptors are a recent technique which reveals geometrical structures in phase space and which are valid for aperiodically time dependent dynamical systems. We discuss a general methodology for constructing them and we discuss a ``heuristic argument'' that explains why this method is successful. We support this argument by explicit calculations on a benchmark problem. Several other benchmark examples are considered that allow us to assess the performance of Lagrangian descriptors with both finite time Lyapunov exponents (FTLEs) and finite time averages of certain components of the vector field (``time averages''). In all cases Lagrangian descriptors are shown to be both more accurate and computationally efficient than these methods. We thank CESGA for computing facilities. This research was supported by MINECO grants: MTM2011-26696, I-Math C3-0104, ICMAT Severo Ochoa project SEV-2011-0087, and CSIC grant OCEANTECH. SW acknowledges the support of the ONR (Grant No. N00014-01-1-0769).
North Atlantic weather regimes: A synoptic study of phase space. M.S. Thesis
NASA Technical Reports Server (NTRS)
Orrhede, Anna Karin
1990-01-01
In the phase space of weather, low frequency variability (LFV) of the atmosphere can be captured in a large scale subspace, where a trajectory connects consecutive large scale weather maps, thus revealing flow changes and recurrences. Using this approach, Vautard applied the trajectory speed minimization method (Vautard and Legras) to atmospheric data. From 37 winters of 700 mb geopotential height anomalies over the North Atlantic and the adjacent land masses, four persistent and recurrent weather patterns, interpreted as weather regimes, were discernable: a blocking regime, a zonal regime, a Greenland anticyclone regime, and an Atlantic regime. These regimes are studied further in terms of maintenance and transitions. A regime survey unveils preferences regarding event durations and precursors for the onset or break of an event. The transition frequencies between regimes vary, and together with the transition times, suggest the existence of easier transition routes. These matters are more systematically studied using complete synoptic map sequences from a number of events.
Designing Heteroclinic and Excitable Networks in Phase Space Using Two Populations of Coupled Cells
NASA Astrophysics Data System (ADS)
Ashwin, Peter; Postlethwaite, Claire
2016-04-01
We give a constructive method for realising an arbitrary directed graph (with no one-cycles) as a heteroclinic or an excitable dynamic network in the phase space of a system of coupled cells of two types. In each case, the system is expressed as a system of first-order differential equations. One of the cell types (the p-cells) interacts by mutual inhibition and classifies which vertex (state) we are currently close to, while the other cell type (the y-cells) excites the p-cells selectively and becomes active only when there is a transition between vertices. We exhibit open sets of parameter values such that these dynamical networks exist and demonstrate via numerical simulation that they can be attractors for suitably chosen parameters.
Phase space theory of quantum–classical systems with nonlinear and stochastic dynamics
Burić, Nikola Popović, Duška B.; Radonjić, Milan; Prvanović, Slobodan
2014-04-15
A novel theory of hybrid quantum–classical systems is developed, utilizing the mathematical framework of constrained dynamical systems on the quantum–classical phase space. Both, the quantum and classical descriptions of the respective parts of the hybrid system are treated as fundamental. Therefore, the description of the quantum–classical interaction has to be postulated, and includes the effects of neglected degrees of freedom. Dynamical law of the theory is given in terms of nonlinear stochastic differential equations with Hamiltonian and gradient terms. The theory provides a successful dynamical description of the collapse during quantum measurement. -- Highlights: •A novel theory of quantum–classical systems is developed. •Framework of quantum constrained dynamical systems is used. •A dynamical description of the measurement induced collapse is obtained.
Adequate bases of phase space master integrals for gg → h at NNLO and beyond
NASA Astrophysics Data System (ADS)
Höschele, Maik; Hoff, Jens; Ueda, Takahiro
2014-09-01
We study master integrals needed to compute the Higgs boson production cross section via gluon fusion in the infinite top quark mass limit, using a canonical form of differential equations for master integrals, recently identified by Henn, which makes their solution possible in a straightforward algebraic way. We apply the known criteria to derive such a suitable basis for all the phase space master integrals in afore mentioned process at next-to-next-to-leading order in QCD and demonstrate that the method is applicable to next-to-next-to-next-to-leading order as well by solving a non-planar topology. Furthermore, we discuss in great detail how to find an adequate basis using practical examples. Special emphasis is devoted to master integrals which are coupled by their differential equations.
Phase space dynamics and control of the quantum particles associated to hypergraph states
NASA Astrophysics Data System (ADS)
Berec, Vesna
2015-05-01
As today's nanotechnology focus becomes primarily oriented toward production and manipulation of materials at the subatomic level, allowing the performance and complexity of interconnects where the device density accepts more than hundreds devices on a single chip, the manipulation of semiconductor nanostructures at the subatomic level sets its prime tasks on preserving and adequate transmission of information encoded in specified (quantum) states. The presented study employs the quantum communication protocol based on the hypergraph network model where the numerical solutions of equations of motion of quantum particles are associated to vertices (assembled with device chip), which follow specific controllable paths in the phase space. We address these findings towards ultimate quest for prediction and selective control of quantum particle trajectories. In addition, presented protocols could represent valuable tool for reducing background noise and uncertainty in low-dimensional and operationally meaningful, scalable complex systems.
Graves, J P; Chapman, I T; Coda, S; Lennholm, M; Albergante, M; Jucker, M
2012-01-01
Virtually collisionless magnetic mirror-trapped energetic ion populations often partially stabilize internally driven magnetohydrodynamic disturbances in the magnetosphere and in toroidal laboratory plasma devices such as the tokamak. This results in less frequent but dangerously enlarged plasma reorganization. Unique to the toroidal magnetic configuration are confined 'circulating' energetic particles that are not mirror trapped. Here we show that a newly discovered effect from hybrid kinetic-magnetohydrodynamic theory has been exploited in sophisticated phase space engineering techniques for controlling stability in the tokamak. These theoretical predictions have been confirmed, and the technique successfully applied in the Joint European Torus. Manipulation of auxiliary ion heating systems can create an asymmetry in the distribution of energetic circulating ions in the velocity orientated along magnetic field lines. We show the first experiments in which large sawtooth collapses have been controlled by this technique, and neoclassical tearing modes avoided, in high-performance reactor-relevant plasmas. PMID:22233634
NASA Astrophysics Data System (ADS)
Olivas, J. D.; Wright, M. C.; Christoffersen, R.; Cone, D. M.; McDanels, S. J.
2010-09-01
Char deposits on recovered fragments of space shuttle Columbia windowpanes were analyzed to further understand the events that occurred during orbiter reentry and breakup. The TEM analysis demonstrated that oxides of aluminum and titanium mixed with silicon oxides to preserve a history of thermal conditions to which portions of the vehicle were exposed. The presence of Ti during the beginning of the deposition process, along with the thermodynamic phase precipitation upon cool down, indicated that temperatures well above the Ti melt point were experienced. The stratified observations implied that additional exothermic reactions, expectedly metal combustion of a Ti-6Al-4V structure, had to occur for oxide formation. Results are significant for aerospace vehicles, where thermal protection system (TPS) breaches could cause material originally designed for substructural applications to be in direct path with reentry plasma.
NASA Astrophysics Data System (ADS)
Shchekinova, E.; Chandre, C.; Uzer, T.
2006-10-01
The multiphoton ionization of hydrogen atoms in a strong elliptically polarized microwave field exhibits complex features that are not observed for ionization in circular and linear polarized fields. Experimental data reveal high sensitivity of ionization dynamics to the small changes of the field polarization. The multidimensional nature of the problem makes widely used diagnostics of dynamics, such as Poincaré surfaces of section, impractical. We analyze the phase-space dynamics using the finite time stability analysis rendered by the fast Lyapunov indicators technique. The concept of zero-velocity surface is used to initialize the calculations and visualize the dynamics. Our analysis provides stability maps calculated for the initial energy at the maximum and below the saddle of the zero-velocity surface. We estimate qualitatively the dependence of ionization thresholds on the parameters of the applied field, such as polarization and scaled amplitude.
NASA Technical Reports Server (NTRS)
Olivas, J. D.; Wright, M. C.; Christoffersen, R.; Cone, D. M.; McDanels, S. J.
2009-01-01
Analyzing the remains of Space Shuttle Columbia has proven technically beneficial years after the vehicle breakup. This investigation focused on charred deposits on fragments of Columbia overhead windowpanes. Results were unexpected relative to the engineering understanding of material performance in a reentry environment. The TEM analysis demonstrated that the oxides of aluminum and titanium mixed with silicon oxides to preserve a history of thermal conditions to which portions of the vehicle were exposed. The presence of Ti during the beginning of the deposition process, along with the thermodynamic phase precipitation upon cool down, indicate that temperatures well above the Ti melt point were experienced. The stratified observations implied that additional exothermic reaction, expectedly metal combustion of a Ti structure, had to be present for oxide formation. Results are significant for aerospace vehicles where thermal protection system (TPS) breaches cause substructures to be in direct path with the reentry plasma. 1
Phase-space analysis and experimental results for secondary focusing at X-ray beamlines
Huang, Rong; Meron, Mati; Kujala, Naresh; Barrea, Raul A.
2011-11-17
Micro-focusing optical devices at synchrotron beamlines usually have a limited acceptance, but more flux can be intercepted if such optics are used to focus secondary sources created by the primary optics. Flux throughput can be maximized by placing the secondary focusing optics close to or exactly at the secondary source position. However, standard methods of beamline optics analysis, such as the lens equation or matching the mirror surface to an ellipse, work poorly when the source-to-optics distance is very short. In this paper the general characteristics of the focusing of beams with Gaussian profiles by a 'thin lens' are analysed under the paraxial approximation in phase space, concluding that the focusing of a beam with a short source-to-optics distance is distinct from imaging the source; slope errors are successfully included in all the formulas so that they can be used to calculate beamline focusing with good accuracy. A method is also introduced to use the thin-lens result to analyse the micro-focusing produced by an elliptically bent trapezoid-shaped Kirkpatrick-Baez mirror. The results of this analysis are in good agreement with ray-tracing simulations and are confirmed by the experimental results of the secondary focusing at the 18-ID Bio-CAT beamline (at the APS). The result of secondary focusing carried out at 18-ID using a single-bounce capillary can also be explained using this phase-space analysis. A discussion of the secondary focusing results is presented at the end of this paper.
Beam Phase Space of an Intense Ion Beam in a Neutralizing Plasma
NASA Astrophysics Data System (ADS)
Seidl, Peter A.; Bazouin, Guillaume; Beneytout, Alice; Lidia, Steven M.; Vay, Jean-Luc; Grote, David P.
2011-10-01
The Neutralized Drift Compression Experiment (NDCX-I) generates high intensity ion beams to explore warm dense matter physics. Transverse final focusing is accomplished with an 8-Tesla, 10-cm long pulsed solenoid magnet combined with a background neutralizing plasma to effectively cancel the space charge field of the ion beam. We report on phase space measurements of the beam before the neutralization channel and of the focused ion beam at the target plane. These are compared to WARP particle-in-cell simulations of the ion beam propagation through the focusing system and neutralizing plasma. Due to the orientation of the plasma sources with respect to the focusing magnet, the plasma distribution within the final focusing lens is strongly affected by the magnetic field, an effect which can influence the peak intensity at the target and which is included in the model of the experiment. Work performed under auspices of U.S. DoE by LLNL, LBNL under Contracts DE-AC52-07NA27344, DE-AC02-05CH1123.
The ROCKSTAR Phase-space Temporal Halo Finder and the Velocity Offsets of Cluster Cores
NASA Astrophysics Data System (ADS)
Behroozi, Peter S.; Wechsler, Risa H.; Wu, Hao-Yi
2013-01-01
We present a new algorithm for identifying dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure; as such, it is named ROCKSTAR (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement). Our method is massively parallel (up to 105 CPUs) and runs on the largest current simulations (>1010 particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). A previous paper has shown ROCKSTAR to have excellent recovery of halo properties; we expand on these comparisons with more tests and higher-resolution simulations. We show a significant improvement in substructure recovery compared to several other halo finders and discuss the theoretical and practical limits of simulations in this regard. Finally, we present results that demonstrate conclusively that dark matter halo cores are not at rest relative to the halo bulk or substructure average velocities and have coherent velocity offsets across a wide range of halo masses and redshifts. For massive clusters, these offsets can be up to 350 km s-1 at z = 0 and even higher at high redshifts. Our implementation is publicly available at http://code.google.com/p/rockstar.
Phase space path-integral formulation of the above-threshold ionization
Milosevic, D. B.
2013-04-15
Atoms and molecules submitted to a strong laser field can emit electrons of high energies in the above-threshold ionization (ATI) process. This process finds a highly intuitive and also quantitative explanation in terms of Feynman's path integral and the concept of quantum orbits [P. Salieres et al., Science 292, 902 (2001)]. However, the connection with the Feynman path-integral formalism is explained only by intuition and analogy and within the so-called strong-field approximation (SFA). Using the phase space path-integral formalism we have obtained an exact result for the momentum-space matrix element of the total time-evolution operator. Applying this result to the ATI we show that the SFA and the so-called improved SFA are, respectively, the zeroth- and the first-order terms of the expansion in powers of the laser-free effective interaction of the electron with the rest of the atom (molecule). We have also presented the second-order term of this expansion which is responsible for the ATI with double scattering of the ionized electron.
TIME-DEPENDENT PHASE SPACE MEASUREMENTS OF THE LONGITUDINALLY COMPRESSING BEAM IN NDCX-I
LBNL; Lidia, S.M.; Bazouin, G.; Seidl, P.A.
2011-03-15
The Neutralized Drift Compression Experiment (NDCXI) generates high intensity ion beams to explore Warm Dense Matter physics. A {approx}150 kV, {approx}500 ns modulating voltage pulse is applied to a {approx}300 kV, 5-10 {mu}s, 25 mA K+ ion beam across a single induction gap. The velocity modulated beam compresses longitudinally during ballistic transport along a space charge neutralizing plasma transport line, resulting in {approx}3A peak current with {approx}2-3 ns pulse durations (FWHM) at the target plane. Transverse final focusing is accomplished with a {approx}8 T, 10 cm long pulsed solenoid magnet. Time-dependent electrostatic focusing in the induction gap, and chromatic aberrations in the final focus optics limit the peak fluenceat the target plane for the compressed beam pulse. We report on time-dependent phase space measurements of the compressed pulse in the ballistic transport beamline, and measurement of the time-dependent radial impulses derived from the interaction of the beam and the induction gap voltage. We present results of start-to-end simulations to benchmark the experiments. Fast correction strategies are discussed with application to both NDCX-I and the soon to be commissioned NDCX-II accelerators.
THE ROCKSTAR PHASE-SPACE TEMPORAL HALO FINDER AND THE VELOCITY OFFSETS OF CLUSTER CORES
Behroozi, Peter S.; Wechsler, Risa H.; Wu, Hao-Yi
2013-01-10
We present a new algorithm for identifying dark matter halos, substructure, and tidal features. The approach is based on adaptive hierarchical refinement of friends-of-friends groups in six phase-space dimensions and one time dimension, which allows for robust (grid-independent, shape-independent, and noise-resilient) tracking of substructure; as such, it is named ROCKSTAR (Robust Overdensity Calculation using K-Space Topologically Adaptive Refinement). Our method is massively parallel (up to 10{sup 5} CPUs) and runs on the largest current simulations (>10{sup 10} particles) with high efficiency (10 CPU hours and 60 gigabytes of memory required per billion particles analyzed). A previous paper has shown ROCKSTAR to have excellent recovery of halo properties; we expand on these comparisons with more tests and higher-resolution simulations. We show a significant improvement in substructure recovery compared to several other halo finders and discuss the theoretical and practical limits of simulations in this regard. Finally, we present results that demonstrate conclusively that dark matter halo cores are not at rest relative to the halo bulk or substructure average velocities and have coherent velocity offsets across a wide range of halo masses and redshifts. For massive clusters, these offsets can be up to 350 km s{sup -1} at z = 0 and even higher at high redshifts. Our implementation is publicly available at http://code.google.com/p/rockstar.
Plesko, Catherine S; Clement, R Ryan; Weaver, Robert P; Bradley, Paul A; Huebner, Walter F
2009-01-01
The mitigation of impact hazards resulting from Earth-approaching asteroids and comets has received much attention in the popular press. However, many questions remain about the near-term and long-term, feasibility and appropriate application of all proposed methods. Recent and ongoing ground- and space-based observations of small solar-system body composition and dynamics have revolutionized our understanding of these bodies (e.g., Ryan (2000), Fujiwara et al. (2006), and Jedicke et al. (2006)). Ongoing increases in computing power and algorithm sophistication make it possible to calculate the response of these inhomogeneous objects to proposed mitigation techniques. Here we present the first phase of a comprehensive hazard mitigation planning effort undertaken by Southwest Research Institute and Los Alamos National Laboratory. We begin by reviewing the parameter space of the object's physical and chemical composition and trajectory. We then use the radiation hydrocode RAGE (Gittings et al. 2008), Monte Carlo N-Particle (MCNP) radiation transport (see Clement et al., this conference), and N-body dynamics codes to explore the effects these variations in object properties have on the coupling of energy into the object from a variety of mitigation techniques, including deflection and disruption by nuclear and conventional munitions, and a kinetic impactor.
Kinetic theory of phase space plateaux in a non-thermal energetic particle distribution
Eriksson, F. Nyqvist, R. M.; Lilley, M. K.
2015-09-15
The transformation of kinetically unstable plasma eigenmodes into hole-clump pairs with temporally evolving carrier frequencies was recently attributed to the emergence of an intermediate stage in the mode evolution cycle, that of an unmodulated plateau in the phase space distribution of fast particles. The role of the plateau as the hole-clump breeding ground is further substantiated in this article via consideration of its linear and nonlinear stability in the presence of fast particle collisions and sources, which are known to affect the production rates and subsequent frequency sweeping of holes and clumps. In particular, collisional relaxation, as mediated by e.g. velocity space diffusion or even simple Krook-type collisions, is found to inhibit hole-clump generation and detachment from the plateau, as it should. On the other hand, slowing down of the fast particles turns out to have an asymmetrically destabilizing/stabilizing effect, which explains the well-known result that collisional drag enhances holes and their sweeping rates but suppresses clumps. It is further demonstrated that relaxation of the plateau edge gradients has only a minor quantitative effect and does not change the plateau stability qualitatively, unless the edge region extends far into the plateau shelf and the corresponding Landau pole needs to be taken into account.
International Space Station Program Phase 3 Integrated Atmosphere Revitalization Subsystem Test
NASA Technical Reports Server (NTRS)
Perry, J. L.; Franks, G. D.; Knox, J. C.
1997-01-01
Testing of the International Space Station (ISS) U.S. Segment baseline configuration of the Atmosphere Revitalization Subsystem (ARS) by NASA's Marshall Space Flight Center (MSFC) was conducted as part of the Environmental Control and Life Support System (ECLSS) design and development program. This testing was designed to answer specific questions regarding the control and performance of the baseline ARS subassemblies in the ISS U.S. Segment configuration. These questions resulted from the continued maturation of the ISS ECLSS configuration and design requirement changes since 1992. The test used pressurized oxygen injection, a mass spectrometric major constituent analyzer, a Four-Bed Molecular Sieve Carbon Dioxide Removal Assembly, and a Trace Contaminant Control Subassembly to maintain the atmospheric composition in a sealed chamber at ISS specifications for 30 days. Human metabolic processes for a crew of four were simulated according to projected ISS mission time lines. The performance of a static feed water electrolysis Oxygen Generator Assembly was investigated during the test preparation phases; however, technical difficulties prevented its use during the integrated test. The Integrated ARS Test (IART) program built upon previous closed-door and open-door integrated testing conducted at MSFC between 1987 and 1992. It is the most advanced test of an integrated ARS conducted by NASA to demonstrate its end-to-end control and overall performance. IART test objectives, facility design, pretest analyses, test and control requirements, and test results are presented.
Dechant, Andreas; Shafier, Shalom Tzvi; Kessler, David A; Barkai, Eli
2016-08-01
The Boltzmann-Gibbs density, a central result of equilibrium statistical mechanics, relates the energy of a system in contact with a thermal bath to its equilibrium statistics. This relation is lost for nonthermal systems such as cold atoms in optical lattices, where the heat bath is replaced with the laser beams of the lattice. We investigate in detail the stationary phase-space probability for Sisyphus cooling under harmonic confinement. In particular, we elucidate whether the total energy of the system still describes its stationary state statistics. We find that this is true for the center part of the phase-space density for deep lattices, where the Boltzmann-Gibbs density provides an approximate description. The relation between energy and statistics also persists for strong confinement and in the limit of high energies, where the system becomes underdamped. However, the phase-space density now exhibits heavy power-law tails. In all three cases we find expressions for the leading-order phase-space density and corrections which break the equivalence of probability and energy and violate energy equipartition. The nonequilibrium nature of the steady state is corroborated by explicit violations of detailed balance. We complement these analytical results with numerical simulations to map out the intricate structure of the phase-space density. PMID:27627290
Observing in space and time the ephemeral nucleation of liquid-to-crystal phase transitions
Yoo, Byung-Kuk; Kwon, Oh-Hoon; Liu, Haihua; Tang, Jau; Zewail, Ahmed H.
2015-01-01
The phase transition of crystalline ordering is a general phenomenon, but its evolution in space and time requires microscopic probes for visualization. Here we report direct imaging of the transformation of amorphous titanium dioxide nanofilm, from the liquid state, passing through the nucleation step and finally to the ordered crystal phase. Single-pulse transient diffraction profiles at different times provide the structural transformation and the specific degree of crystallinity (η) in the evolution process. It is found that the temporal behaviour of η exhibits unique ‘two-step' dynamics, with a robust ‘plateau' that extends over a microsecond; the rate constants vary by two orders of magnitude. Such behaviour reflects the presence of intermediate structure(s) that are the precursor of the ordered crystal state. Theoretically, we extend the well-known Johnson–Mehl–Avrami–Kolmogorov equation, which describes the isothermal process with a stretched-exponential function, but here over the range of times covering the melt-to-crystal transformation. PMID:26478194
NASA Astrophysics Data System (ADS)
García-García, Reinaldo; Domínguez, Daniel
2014-02-01
We define the violation fraction ν as the cumulative fraction of time that the entropy change is negative during single realizations of processes in phase space. This quantity depends on both the number of degrees of freedom N and the duration of the time interval τ. In the large-τ and large-N limit we show that, for ergodic and microreversible systems, the mean value of ν scales as <ν(N,τ)>˜(τN1/1+α)-1. The exponent α is positive and generally depends on the protocol for the external driving forces, being α =1 for a constant drive. As an example, we study a nontrivial model where the fluctuations of the entropy production are non-Gaussian: an elastic line driven at a constant rate by an anharmonic trap. In this case we show that the scaling of <ν> with N and τ agrees with our result. Finally, we discuss how this scaling law may break down in the vicinity of a continuous phase transition.
Structural Diversity of Arthropod Biophotonic Nanostructures Spans Amphiphilic Phase-Space
Saranathan, Vinod Kumar; Seago, Ainsley E.; Sandy, Alec; Narayanan, Suresh; Mochrie, Simon G.J.; Dufresne, Eric R.; Cao, Hui; Osuji, Chinedum O.; Prum, Richard Owen
2015-05-04
Many organisms, especially arthropods, produce vivid interference colors using diverse mesoscopic (100-350 nm) integumentary biophotonic nanostructures that are increasingly being investigated for technological applications. Despite a century of interest, precise structural knowledge of many biophotonic nanostructures and the mechanisms controlling their development remain tentative, when such knowledge can open novel biomimetic routes to facilely self-assemble tunable, multifunctional materials. Here, we use synchrotron small-angle X-ray scattering and electron microscopy to characterize the photonic nanostructure of 140 integumentary scales and setae from ~127 species of terrestrial arthropods in 85 genera from 5 orders. We report a rich nanostructural diversity, including triply periodic bicontinuous networks, close-packed spheres, inverse columnar, perforated lamellar, and disordered spongelike morphologies, commonly observed as stable phases of amphiphilic surfactants, block copolymer, and lyotropic lipid-water systems. Diverse arthropod lineages appear to have independently evolved to utilize the self-assembly of infolding lipid-bilayer membranes to develop biophotonic nanostructures that span the phase-space of amphiphilic morphologies, but at optical length scales.
Scalar field cosmology in the energy phase-space-unified description of dynamics
Szydlowski, Marek; Hrycyna, Orest E-mail: hrycyna@kul.lublin.pl
2009-01-15
In this letter we apply dynamical system methods to study all evolutional paths admissible for all initial conditions of the FRW cosmological model with a non-minimally coupled to gravity scalar field and a barotropic fluid. We choose ''energy variables'' as phase variables. We reduce dynamics to a 3-dimensional dynamical system for an arbitrary potential of the scalar field in the phase space variables ({kappa}{phi}-dot /6{sup 1/2}H, {kappa}V{sup 1/2}/3{sup 1/2}H, {kappa}{phi}/6{sup 1/2}). After postulating the potential parameter {Gamma} as a function of {lambda} (defined as -V'/V) we reduce whole dynamics to a 3-dimensional dynamical system and study evolutional paths leading to current accelerating expansion. If we restrict the form of the potential then we will obtain a 2-dimensional dynamical system. We use the dynamical system approach to find a new generic quintessence scenario of approaching to the de Sitter attractor which appears only for the case of non-vanishing coupling constant.
Observing in space and time the ephemeral nucleation of liquid-to-crystal phase transitions.
Yoo, Byung-Kuk; Kwon, Oh-Hoon; Liu, Haihua; Tang, Jau; Zewail, Ahmed H
2015-01-01
The phase transition of crystalline ordering is a general phenomenon, but its evolution in space and time requires microscopic probes for visualization. Here we report direct imaging of the transformation of amorphous titanium dioxide nanofilm, from the liquid state, passing through the nucleation step and finally to the ordered crystal phase. Single-pulse transient diffraction profiles at different times provide the structural transformation and the specific degree of crystallinity (η) in the evolution process. It is found that the temporal behaviour of η exhibits unique 'two-step' dynamics, with a robust 'plateau' that extends over a microsecond; the rate constants vary by two orders of magnitude. Such behaviour reflects the presence of intermediate structure(s) that are the precursor of the ordered crystal state. Theoretically, we extend the well-known Johnson-Mehl-Avrami-Kolmogorov equation, which describes the isothermal process with a stretched-exponential function, but here over the range of times covering the melt-to-crystal transformation. PMID:26478194
Observing in space and time the ephemeral nucleation of liquid-to-crystal phase transitions
NASA Astrophysics Data System (ADS)
Yoo, Byung-Kuk; Kwon, Oh-Hoon; Liu, Haihua; Tang, Jau; Zewail, Ahmed H.
2015-10-01
The phase transition of crystalline ordering is a general phenomenon, but its evolution in space and time requires microscopic probes for visualization. Here we report direct imaging of the transformation of amorphous titanium dioxide nanofilm, from the liquid state, passing through the nucleation step and finally to the ordered crystal phase. Single-pulse transient diffraction profiles at different times provide the structural transformation and the specific degree of crystallinity (η) in the evolution process. It is found that the temporal behaviour of η exhibits unique `two-step' dynamics, with a robust `plateau' that extends over a microsecond; the rate constants vary by two orders of magnitude. Such behaviour reflects the presence of intermediate structure(s) that are the precursor of the ordered crystal state. Theoretically, we extend the well-known Johnson-Mehl-Avrami-Kolmogorov equation, which describes the isothermal process with a stretched-exponential function, but here over the range of times covering the melt-to-crystal transformation.
Phase space theory of evaporation in neon clusters: the role of quantum effects.
Calvo, F; Parneix, P
2009-12-31
Unimolecular evaporation of neon clusters containing between 14 and 148 atoms is theoretically investigated in the framework of phase space theory. Quantum effects are incorporated in the vibrational densities of states, which include both zero-point and anharmonic contributions, and in the possible tunneling through the centrifugal barrier. The evaporation rates, kinetic energy released, and product angular momentum are calculated as a function of excess energy or temperature in the parent cluster and compared to the classical results. Quantum fluctuations are found to generally increase both the kinetic energy released and the angular momentum of the product, but the effects on the rate constants depend nontrivially on the excess energy. These results are interpreted as due to the very few vibrational states available in the product cluster when described quantum mechanically. Because delocalization also leads to much narrower thermal energy distributions, the variations of evaporation observables as a function of canonical temperature appear much less marked than in the microcanonical ensemble. While quantum effects tend to smooth the caloric curve in the product cluster, the melting phase change clearly keeps a signature on these observables. The microcanonical temperature extracted from fitting the kinetic energy released distribution using an improved Arrhenius form further suggests a backbending in the quantum Ne(13) cluster that is absent in the classical system. Finally, in contrast to delocalization effects, quantum tunneling through the centrifugal barrier does not play any appreciable role on the evaporation kinetics of these rather heavy clusters. PMID:20028160
Trugenberger, Carlo A
2015-12-01
Recently I proposed a simple dynamical network model for discrete space-time that self-organizes as a graph with Hausdorff dimension d(H)=4. The model has a geometric quantum phase transition with disorder parameter (d(H)-d(s)), where d(s) is the spectral dimension of the dynamical graph. Self-organization in this network model is based on a competition between a ferromagnetic Ising model for vertices and an antiferromagnetic Ising model for edges. In this paper I solve a toy version of this model defined on a bipartite graph in the mean-field approximation. I show that the geometric phase transition corresponds exactly to the antiferromagnetic transition for edges, the dimensional disorder parameter of the former being mapped to the staggered magnetization order parameter of the latter. The model has a critical point with long-range correlations between edges, where a continuum random geometry can be defined, exactly as in Kazakov's famed 2D random lattice Ising model but now in any number of dimensions. PMID:26764755
Critical space-time networks and geometric phase transitions from frustrated edge antiferromagnetism
NASA Astrophysics Data System (ADS)
Trugenberger, Carlo A.
2015-12-01
Recently I proposed a simple dynamical network model for discrete space-time that self-organizes as a graph with Hausdorff dimension dH=4 . The model has a geometric quantum phase transition with disorder parameter (dH-ds) , where ds is the spectral dimension of the dynamical graph. Self-organization in this network model is based on a competition between a ferromagnetic Ising model for vertices and an antiferromagnetic Ising model for edges. In this paper I solve a toy version of this model defined on a bipartite graph in the mean-field approximation. I show that the geometric phase transition corresponds exactly to the antiferromagnetic transition for edges, the dimensional disorder parameter of the former being mapped to the staggered magnetization order parameter of the latter. The model has a critical point with long-range correlations between edges, where a continuum random geometry can be defined, exactly as in Kazakov's famed 2D random lattice Ising model but now in any number of dimensions.
Phase space theory of Bose-Einstein condensates and time-dependent modes
Dalton, B.J.
2012-10-15
A phase space theory approach for treating dynamical behaviour of Bose-Einstein condensates applicable to situations such as interferometry with BEC in time-dependent double well potentials is presented. Time-dependent mode functions are used, chosen so that one, two, Horizontal-Ellipsis highly occupied modes describe well the physics of interacting condensate bosons in time dependent potentials at well below the transition temperature. Time dependent mode annihilation, creation operators are represented by time dependent phase variables, but time independent total field annihilation, creation operators are represented by time independent field functions. Two situations are treated, one (mode theory) is where specific mode annihilation, creation operators and their related phase variables and distribution functions are dealt with, the other (field theory) is where only field creation, annihilation operators and their related field functions and distribution functionals are involved. The field theory treatment is more suitable when large boson numbers are involved. The paper focuses on the hybrid approach, where the modes are divided up between condensate (highly occupied) modes and non-condensate (sparsely occupied) modes. It is found that there are extra terms in the Ito stochastic equations both for the stochastic phases and stochastic fields, involving coupling coefficients defined via overlap integrals between mode functions and their time derivatives. For the hybrid approach both the Fokker-Planck and functional Fokker-Planck equations differ from those derived via the correspondence rules, the drift vectors are unchanged but the diffusion matrices contain additional terms involving the coupling coefficients. Results are also presented for the combined approach where all the modes are treated as one set. Here both the Fokker-Planck and functional Fokker-Planck equations are exactly the same as those derived via the correspondence rules. However, although the
An extended pressure finite element space for two-phase incompressible flows with surface tension
NASA Astrophysics Data System (ADS)
Groß, Sven; Reusken, Arnold
2007-05-01
We consider a standard model for incompressible two-phase flows in which a localized force at the interface describes the effect of surface tension. If a level set (or VOF) method is applied then the interface, which is implicitly given by the zero level of the level set function, is in general not aligned with the triangulation that is used in the discretization of the flow problem. This non-alignment causes severe difficulties w.r.t. the discretization of the localized surface tension force and the discretization of the flow variables. In cases with large surface tension forces the pressure has a large jump across the interface. In standard finite element spaces, due to the non-alignment, the functions are continuous across the interface and thus not appropriate for the approximation of the discontinuous pressure. In many simulations these effects cause large oscillations of the velocity close to the interface, so-called spurious velocities. In this paper, for a simplified model problem, we give an analysis that explains why known (standard) methods for discretization of the localized force term and for discretization of the pressure variable often yield large spurious velocities. In the paper [S. Groß, A. Reusken, Finite element discretization error analysis of a surface tension force in two-phase incompressible flows, Preprint 262, IGPM, RWTH Aachen, SIAM J. Numer. Anal. (accepted for publication)], we introduce a new and accurate method for approximation of the surface tension force. In the present paper, we use the extended finite element space (XFEM), presented in [N. Moes, J. Dolbow, T. Belytschko, A finite element method for crack growth without remeshing, Int. J. Numer. Meth. Eng. 46 (1999) 131-150; T. Belytschko, N. Moes, S. Usui, C. Parimi, Arbitrary discontinuities in finite elements, Int. J. Numer. Meth. Eng. 50 (2001) 993-1013], for the discretization of the pressure. We show that the size of spurious velocities is reduced substantially, provided we
Shimobaba, Tomoyoshi; Makowski, Michał; Nagahama, Yuki; Endo, Yutaka; Hirayama, Ryuji; Hiyama, Daisuke; Hasegawa, Satoki; Sano, Marie; Kakue, Takashi; Oikawa, Minoru; Sugie, Takashige; Takada, Naoki; Ito, Tomoyoshi
2016-05-20
We propose two calculation methods of generating color computer-generated holograms (CGHs) with the random phase-free method and color space conversion in order to improve the image quality and accelerate the calculation. The random phase-free method improves the image quality in monochrome CGH, but it is not performed in color CGH. We first aimed to improve the image quality of color CGH using the random phase-free method and then to accelerate the color CGH generation with a combination of the random phase-free method and color space conversion method, which accelerates the color CGH calculation due to down-sampling of the color components converted by color space conversion. To overcome the problem of image quality degradation that occurs due to the down-sampling of random phases, the combination of the random phase-free method and color space conversion method improves the quality of reconstructed images and accelerates the color CGH calculation. We demonstrated the effectiveness of the proposed method in simulation, and in this paper discuss its application to lensless zoomable holographic projection. PMID:27411145
NASA Astrophysics Data System (ADS)
Li, Mi; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Chang, Lingqian; Chen, Yuan
2016-05-01
Phase fluctuation effect is an important phenomenon on bit error rate (BER) performance on fluctuation channel in space downlink optical communication system. During research process, both intensity scintillation and phase fluctuation caused by atmospheric turbulence have been considered on fluctuation channel. Through the analysis of simulation results, the influence of phase fluctuation is not sensitive for wavelength and APD gain factor at high data rate. Besides, receiving diameter and divergence angle can be adjusted properly in order to obtain optimal BER performance. This work is helpful to the research of phase fluctuation and the design of practical system.
SIR phasing by combination of SOLVE/RESOLVE and dual-space fragment extension involving OASIS
NASA Astrophysics Data System (ADS)
He, Yao; Gu, Yuan-Xin; Lin, Zheng-Jiong; Zheng, Chao-De; Fan, Hai-Fu
2007-10-01
A new phasing procedure has been proposed for dealing with single isomorphous replacement (SIR) x-ray diffraction data. The procedure combines SOLVE/RESOLVE with the dual-space fragment extension involving OASIS. Two sets of SIR data at 0.28 nm resolution taken from the protein (R)-phycoerythrin (PDB code: 1LIA) were used in the test. For one of the two SIR data sets, a default run of SOLVE/RESOLVE based on the heavy-atom substructure found by SHLEXD led automatically to an interpretable electron density map. OASIS could not effectively improve the result. For the other set of SIR data, SOLVE/RESOLVE resulted in a fragmented model consisting of 454 of the total 668 residues, in which only 29 residues were docked into the sequence. Based on this model, 7 iteration cycles of OASIS-DM-RESOLVE (build only) yielded automatically a model of 547 residues with 133 residues docked into the sequence. The overall-averaged phase error decreased considerably and the quality of electron density map was improved significantly. Two more cycles of iterative OASIS-DM-RESOLVE were carried out, in which the output phases and figures of merit from DM were merged with that from the original run of SOLVE/RESOLVE before they were passed onto RESOLVE (build only). This led automatically to a model containing 452 residues with 173 docked into the sequence. The resultant electron density map is manually traceable. It is concluded that when results of SOLVE/RESOLVE are not sufficiently satisfactory, the combination of SOLVE/RESOLVE and OASIS-DM-RESOLVE (build only) may significantly improve them.
NASA Technical Reports Server (NTRS)
Fabris, Gracio
1992-01-01
Two-phase energy conversion systems could be liquid metal magnetohydrodynamic (LMMHD) with no moving parts or two-phase turbines. Both of them are inherently simple and reliable devices which can operate in a wide range of temperatures. Their thermal efficiency is significantly higher than for conventional cycles due to reheat of vapor by liquid phase during the energy converting expansion. Often they can be more easily coupled to heat sources. These features make two-phase systems particularly promising for space application. Insufficient research has been done in the past. So far achieved LMMHD generator and two-phase turbine efficiencies are in the 40 to 45 percent range. However if certain fluid dynamic and design problems are resolved these efficiencies could be brought into the range of 70 percent. This would make two-phase systems extremely competitive as compared to present or other proposed conversion system for space. Accordingly, well directed research effort on potential space applications of two-phase conversion systems would be a wise investment.
NASA Astrophysics Data System (ADS)
Fabris, Gracio
Two-phase energy conversion systems could be liquid metal magnetohydrodynamic (LMMHD) with no moving parts or two-phase turbines. Both of them are inherently simple and reliable devices which can operate in a wide range of temperatures. Their thermal efficiency is significantly higher than for conventional cycles due to reheat of vapor by liquid phase during the energy converting expansion. Often they can be more easily coupled to heat sources. These features make two-phase systems particularly promising for space application. Insufficient research has been done in the past. So far achieved LMMHD generator and two-phase turbine efficiencies are in the 40 to 45 percent range. However if certain fluid dynamic and design problems are resolved these efficiencies could be brought into the range of 70 percent. This would make two-phase systems extremely competitive as compared to present or other proposed conversion system for space. Accordingly, well directed research effort on potential space applications of two-phase conversion systems would be a wise investment.
Lombardini, Richard; Poirier, Bill
2006-09-01
A particular basis set method developed by one of the authors, involving maximally localized orthogonal Weyl-Heisenberg wavelets (or "weylets") and a phase space truncation scheme, has been successfully applied to exact quantum calculations for many degrees of freedom (DOF's) [B. Poirier and A. Salam, J. Chem. Phys. 121, 1740 (2004)]. However, limitations in accuracy arise in the many-DOF case, owing to memory limits on conventional computers. This paper addresses this accuracy limitation by introducing phase space region operators (PSRO's) that customize individual weylet basis functions for the problem of interest. The construction of the PSRO's is straightforward, and does not require a priori knowledge of the desired eigenstates. The PSRO, when applied to weylets, as well as to simple phase space Gaussian basis functions, exhibits remarkable improvements in accuracy, reducing computed eigenvalue errors by orders of magnitude. The method is applied to various model systems at varying DOF's. PMID:17025784
NASA Astrophysics Data System (ADS)
Korf, Lisa A.; Schroeck, Franklin E.
2015-12-01
We consider an effect algebra of phase space localization operators for a quantum mechanical Hilbert space that contains no non-trivial projections, and the C*-algebra generated by it. This C∗-algebra forms an informationally complete set in the original Hilbert space. Its elements are shown to have singular-value-based decompositions that permit their characterization in terms of limits of linear combinations of products of pairs of the phase space fuzzy localization operators. Through these results, it is shown that the informational completeness of the C*-algebra can be greatly reduced to the informational completeness of the set of products of pairs formed from the elements of the effect algebra.
Yang, Xuefei; Xia, Ligang; Huang, Jun; Wang, Jianping
2014-01-01
Iatrogenic injuries caused by barium enema are rarely reported. Following a phased surgical protocol for up to one year, we have successfully treated a patient with rectal injury and severe infection of the pelvic floor space complicated with retention of large amounts of barium and vaginal fistula. In this article, the phased surgery planning for the treatment of rectal injury complicated with vaginal fistula is discussed in terms of the pros and cons, and the observed effect and evolution of barium retained in the pelvic floor space are described. PMID:25405155
Extended phase space thermodynamics and P-V criticality of charged black holes in Brans-Dicke theory
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Armanfard, Z.
2015-10-01
Motivated by conformal relation between dilaton gravity and Brans-Dicke theory, in this paper, we are taking into account extended phase space thermodynamics to investigate phase transition of charged black holes. We regard spherically symmetric charged black hole solutions in the presence of a scalar field in both Einstein and Jordan frames and calculate related conserved and thermodynamic quantities. Then, we study the analogy of the black hole solution with the Van der Waals liquid-gas system in the extended phase space by considering the cosmological constant proportional to thermodynamical pressure. We obtain critical values of thermodynamic coordinates and plot P-V and G-T diagrams to study the phase transition points and compare the results of dilaton gravity and Brans-Dicke theory.