Variable-Period Undulators For Synchrotron Radiation
Shenoy, Gopal (Naperville, IL); Lewellen, John (Plainfield, IL); Shu, Deming (Darien, IL); Vinokurov, Nikolai (Novosibirsk, RU)
2005-02-22T23:59:59.000Z
A new and improved undulator design is provided that enables a variable period length for the production of synchrotron radiation from both medium-energy and high-energy storage rings. The variable period length is achieved using a staggered array of pole pieces made up of high permeability material, permanent magnet material, or an electromagnetic structure. The pole pieces are separated by a variable width space. The sum of the variable width space and the pole width would therefore define the period of the undulator. Features and advantages of the invention include broad photon energy tunability, constant power operation and constant brilliance operation.
Short-Period RF Undulator for a SASE Nanometer source
Jay L. Hirshfield
2001-12-21T23:59:59.000Z
Analysis is described towards development of a RF undulator with a period < 1 cm, an undulator parameter K of the order of unity, and a gap greater than 2.25 mm. The application for the undulator is for a SASE source to produce 1 nm wavelength radiation using a low energy electron beam in the range 1-2 GeV. Particle orbit calculations in a conventional standing-wave resonator configuration show that the presence of a co-propagating component of RF field can cause deleterious motion for the undulating electrons that can seriously degrade their radiation spectrum. To obviate this problem, resonator designs were devised in which only the counter-propagating field components interact with the particles. Two resonator configurations with the same undulator parameter K = 0.4 have been devised and are described in this report.
LS Note 340 - New Design for a 27-mm Period Undulator for the...
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Design for a 27-mm Period Undulator for the MBA Lattice Melike Abliz, John Grimmer, Isaac Vasserman Abstract By further optimizing the dimensions of a 27-mm period undulator's...
Harmonics suppression effect of the quasi-periodic undulator in SASE free-electron-laser
Ai-Lin Wu; Qi-Ka Jia; He-Ting Li
2013-05-03T23:59:59.000Z
In this paper, the harmonics suppression effect of QPUs in SASE FEL is investigated. The numerical results show that the harmonics power is reduced by using QPUs, but the fundamental radiation power also has a pronounced decrease as the saturation length gets very long. The cases of employing QPUs as parts of undulators are studied. The calculations show that if the fraction of QPUs and their offgap are appropriate in an undulator system, the harmonics radiation could be suppressed remarkably, meanwhile the fundamental saturation length does not increase too much.
The U5. 0 Undulator for the ALS
Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.
1991-05-01T23:59:59.000Z
The U5.0 Undulator, an 89 period, 5 cm period length, 4.6 m long insertion device has been designed and is in fabrication. This undulator will be the first high brightness source, in the 50 to 1500 eV range, for the Advanced Light Source (ALS) and is scheduled for completion in 1992. A modular hybrid configuration utilizing Nd-Fe-B permanent magnet material and vanadium permendur is used that achieves 0.837 Tesla effective peak field. Correction of the vertical field integral is with permanent magnet rotors at the ends. Gap adjustment is with an arrangement of roller screws, chains drives, a gear reduction unit and a stepper motor driven by a closed loop control system. The vacuum chamber design is a two-piece, machined and welded 5083-H321 aluminum construction of 5.1 m length. Magnetic design, subsystem design and fabrication progress are presented. 12 refs., 4 figs., 2 tabs.
Gottschalk, Steven C. [STI, Washington, USA; Benson, Steven V. [JLAB; Moore, Steven Wesley [JLAB
2013-05-01T23:59:59.000Z
Recently the JLAB FEL has demonstrated 150 W at 400 nm and 200 W at 700 nm using a 33mm period undulator designed and built by STI Optronics. This paper describes the undulator design and performance. Two key requirements were low phase error, zero steering and offset end fields and small rms trajectory errors. We will describe a new genetic algorithm that allowed phase error minimization to 1.8 degrees while exceeding specifications. The mechanical design, control system and EPICS interface will also be summarized.
ANL/APS/LS-313 Short-Period APPLE II Undulator for Generating 12-15 keV
Kemner, Ken
regarding power management even in the future for high-current storage ring operations at 200 mA. The code APPLE II design. In this note, we present magnet design calculations and radiation calculations over four times more power in the central cone of the first harmonic than Undulator A at 12.9 ke
Tatchyn, Roman O. (Palo Alto, CA); Csonka, Paul L. (Eugene, OR); Cremer, Jay T. (Burlingame, CA)
1990-12-11T23:59:59.000Z
Micropole undulators for use in the generation of x-rays from moving charged particles are disclosed. Two rows of spaced apart poles are arranged so that each pole produces a magnetic field aligned with all other similar fields. The poles are the ends of "C"-shaped magnets. In each row, adjacent poles are separated by spacers made of a superconducting material.
Tatchyn, R.O.; Csonka, P.L.; Cremer, J.T.
1990-12-11T23:59:59.000Z
Micropole undulators for use in the generation of x-rays from moving charged particles are disclosed. Two rows of spaced apart poles are arranged so that each pole produces a magnetic field aligned with all other similar fields. The poles are the ends of C''-shaped magnets. In each row, adjacent poles are separated by spacers made of a superconducting material. 11 figs.
Tuning The Laser Heater Undulator
Wolf, Zackary
2010-12-03T23:59:59.000Z
The laser heater undulator for the LCLS requires different tuning techniques than the main undulators. It is a pure permanent magnet (PPM) undulator, rather than the hybrid design of the main undulators. The PPM design allows analytic calculation of the undulator fields. The calculations let errors be introduced and correction techniques be derived. This note describes how the undulator was modelled, and the methods which were found to correct potential errors in the undulator. The laser heater undulator for the LCLS is a pure permanent magnet device requiring different tuning techniques than the main undulators. In this note, the laser heater undulator is modelled and tuning techniques to compensate various errors are derived.
Transmission Grating Measurements of Undulator K
Bionta, R. M.
2010-12-01T23:59:59.000Z
This study was undertaken to understand the practicalities of determine K differences in the undulator modules by measuring single-shot x-ray spectra of the spontaneous radiation with a transmissive grating spectrometer under development to measure FEL spectra. Since the quality of the FEL is dependent on a uniform K value in all the undulator modules, being able to measure the relative undulator K values is important. Preliminary results were presented in a presentation, 'Use of FEL Off-Axis Zone Plate Spectrometer to Measure Relative K by the Pinhole/Centroid Method', at the 'LCLS Beam-Based Undulator K Measurements Workshop' on November 14, 2005 (UCRL-PRES-217281). This study applies equally well to reflective gratings of the appropriate period and inclinations.
Wolf, Zachary
2010-11-24T23:59:59.000Z
This note presents the test plan for the LCLS undulators. The undulators will be measured and tuned in the Magnetic Measurement Facility at SLAC. The requirements for tuning are well established and are summarized. A brief discussion of the measurement equipment is presented. This is followed by the detailed test plan in which each step is enumerated. Finally, the measurement results and storage format are presented. The LCLS consists of 33 undulator segments, hereafter referred to as undulators, plus 6 spares and one reference undulator. The undulators must be tuned to meet strict requirements. They must also be fiducialized to allow alignment with other components. This note details the plan for tuning and fiducializing the LCLS undulators. The note begins with the list of tuning and fiducialization requirements. The laboratory in which the work will be performed and the relevant equipment is then briefly described. This is followed by a detailed test plan in which all the steps of tuning and fiducialization are enumerated.
LCLS Undulator Fiducialization Plan
Wolf, Zachary
2010-11-24T23:59:59.000Z
This note presents the LCLS undulator fiducialization plan. The undulators will be fiducialized in the Magnetic Measurement Facility at SLAC. The note begins by summarizing the requirements for the fiducialization. A brief discussion of the measurement equipment is presented, followed by the methods used to perform the fiducialization and check the results. This is followed by the detailed fiducialization plan in which each step is enumerated. Finally, the measurement results and data storage format are presented.
Self-Stimulated Undulator Klystron
Bessonov, E G; Mikhailichenko, A A
2011-01-01T23:59:59.000Z
The Self Stimulated Undulator Klystron (SSUK) and its possible applications in the Particle Accelerator Physics, incoherent Self-Stimulated Undulator Radiation Sources (SSUR) and Free-Electron Lasers (FEL) are discussed.
The Properties of Undulator Radiation
Howells, M.R.
2011-01-01T23:59:59.000Z
Experiments with an Optical Klystron Installed on the VEPP-3the transverse optical klystron undulator at Brookhaven, BL
Use of Dynamical Undulator Mechanism to Produce Short Wavelength Radiation in Volume FEL (VFEL)
V. G. Baryshevsky; K. G. Batrakov
2002-09-06T23:59:59.000Z
VFEL lasing in system with dynamical undulator is described. In this system radiation of long wavelength creates the undulator for lasing on shorter wavelength. Two diffraction gratings with different spatial periods form VFEL resonator. The grating with longer period pumps the resonator with long wavelength radiation to provide necessary amplitude of undulator field. The grating with shorter period makes mode selection for short wavelength radiation. Lasing of such a system in terahertz frequency range is discussed.
R. C. O'Brien; J. E. O'Brien; C. M. Stoots; X. Zhang; S. C. Farmer; T. L. Cable; J. A. Setlock
2011-11-01T23:59:59.000Z
A series of 5 cm by 5 cm bi-supported Solid Oxide Electrolysis Cells (SOEC) were produced by NASA for the Idaho National Laboratory (INL) and tested under the INL High Temperature Steam Electrolysis program. The results from the experimental demonstration of cell operation for both hydrogen production and operation as fuel cells is presented. An overview of the cell technology, test apparatus and performance analysis is also provided. The INL High Temperature Steam Electrolysis laboratory has developed significant test infrastructure in support of single cell and stack performance analyses. An overview of the single cell test apparatus is presented. The test data presented in this paper is representative of a first batch of NASA's prototypic 5 cm by 5 cm SOEC single cells. Clearly a significant relationship between the operational current density and cell degradation rate is evident. While the performance of these cells was lower than anticipated, in-house testing at NASA Glenn has yielded significantly higher performance and lower degradation rates with subsequent production batches of cells. Current post-test microstructure analyses of the cells tested at INL will be published in a future paper. Modification to cell compositions and cell reduction techniques will be altered in the next series of cells to be delivered to INL with the aim to decrease the cell degradation rate while allowing for higher operational current densities to be sustained. Results from the testing of new batches of single cells will be presented in a future paper.
Flying radio frequency undulator
Kuzikov, S. V.; Vikharev, A. A. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Savilov, A. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod (Russian Federation)
2014-07-21T23:59:59.000Z
A concept for the room-temperature rf undulator, designed to produce coherent X-ray radiation by means of a relatively low-energy electron beam and pulsed mm-wavelength radiation, is proposed. The “flying” undulator is a high-power short rf pulse co-propagating together with a relativistic electron bunch in a helically corrugated waveguide. The electrons wiggle in the rf field of the ?1st spatial harmonic with the phase velocity directed in the opposite direction in respect to the bunch velocity, so that particles can irradiate high-frequency Compton's photons. A high group velocity (close to the speed of light) ensures long cooperative motion of the particles and the co-propagating rf pulse.
An Undulator Based Polarized Positron Source for CLIC
Liu, Wanming; /Argonne; Gai, Wei; /Argonne; Rinolfi, Louis; /CERN; Sheppard, John; /SLAC
2012-07-02T23:59:59.000Z
A viable positron source scheme is proposed that uses circularly polarized gamma rays generated from the main 250 GeV electron beam. The beam passes through a helical superconducting undulator with a magnetic field of {approx} 1 Tesla and a period of 1.15 cm. The gamma-rays produced in the undulator in the energy range between {approx} 3 MeV - 100 MeV will be directed to a titanium target and produce polarized positrons. The positrons are then captured, accelerated and transported to a Pre-Damping Ring (PDR). Detailed parameter studies of this scheme including positron yield, and undulator parameter dependence are presented. Effects on the 250 GeV CLIC main beam, including emittance growth and energy loss from the beam passing through the undulator are also discussed.
Thermal Tests of Undulator Quad
Fisher, Andrew; /SLAC; ,
2010-11-18T23:59:59.000Z
Running at the nominal temperature, the undulator quadrupole has a several degree temperature increase. This note describes the test used to determine the effect on the undulator integrals from the temperature gradient caused by the heat from the quadrupole conducting down the beam pipe. The undulator quadrupoles running at their nominal current of 4 amps heat up approximately 4 degrees Celsius; this magnet in turn heats up the beampipe which goes into the undulator. The heating ends up introducing a thermal gradient across the undulator which causes small changes in the magnetic field of the heated poles. By measuring the temperature change in the poles we can model the effects on the field and determine what the magnetic errors will be.
Undulator-Based Production of Polarized Photons
Professor Kirk McDonald
2008-05-29T23:59:59.000Z
"Project Title: Undulator-Based Production of Polarized Photons" DOE Contract Number: FG02-04ER41355 Principal Investigator: Prof. Kirk McDonald Period of Performance: 09/10/2004 thru 08/31/2006 This award was to fund Princeton's activity on SLAC experiment E166, "Undulator-Based Production of Polarized Positrons" which was performed at SLAC during June and September 2005. Princeton U. fabricated a magnetic spectrometer for this experiment, and participated in the commissioning, operation, and analysis of the experiment, for which Prof. McDonald was a co-spokesperson. The experiment demonstrated that an intense positron beam with 80% longitudinal polarization could be generated by conversion of MeVenergy circularly polarized photons in a thin target, which photons were generated by passage of high-energy electrons through a helical undulator. This technique has since been adopted as the baseline for the polarized positron source of the proposed International Linear Collider. Results of the experiment have been published in Physical Review Letters, vol 100, p 210801 (2008) [see attached .pdf file], and a longer paper is in preparation.
On-Axis Brilliance and Power of In-Vacuum Undulators for The...
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NdFeB (with the exception of one undulator made of SmCo), we have performed design optimization of the actual geometry for several periods and gaps covering gap-to-period ratios...
New designs of polarized electromagnetic undulators at SOLEIL
Marcouille, O.; Chubar, O.; Dael, A.; Level, M.-P. [Synchrotron SOLEIL, L'Orme des Merisiers-Saint-Aubin, BP 48 - F 91192 Gif-sur-Yvette (France)
2004-05-12T23:59:59.000Z
Two electromagnetic undulators have been designed on the SOLEIL light source to produce variable polarizations in the range 5 eV - 200 eV. The first one (HU640) is a 10 m undulator composed of 16 periods of 640 mm. It will produce photons of 5 eV - 40 eV with all kinds of switchable (1 Hz) polarization states by varying the horizontal and vertical magnetic field components as well as the phase shift between them. This operation is achieved by means of three sets of coils mounted on non magnetic holders in a special arrangement. One set is dedicated to generate the horizontal component. Two other sets, shifted the one from the other by a quarter of period along the ID axis produce the vertical component with a possible continuous translation varying from +/- half a period without any carriage motion. The second undulator (HU256) operating between 10 eV and 200 eV is a 3.6 m undulator composed of two sequences of alternated dipoles. The two series of dipoles produce either the horizontal component of the magnetic field or the vertical one and are separated from each other by a quarter of period. Linear horizontal/vertical and elliptical polarized light is produced by varying independently the currents in the main coils. Quasi-periodic operation mode dedicated to harmonic rejection is achieved by the addition of 'backleg' coils installed on the dipole legs. In this paper, we present the magnetic designs and the mechanical structures of the undulators as well as the expected optical performances.
Photon emission by ultra-relativistic positrons in crystalline undulators: the high-energy regime
Krause, W; Solov'yov, A V; Greiner, W
2015-01-01T23:59:59.000Z
This paper discusses the undulator radiation emitted by high-energy positrons during planar channeling in periodically bent crystals. We demonstrate that the construction of the undulator for positrons with energies of 10 GeV and above is only possible if one takes into account the radiative energy losses. The frequency of the undulator radiation depends on the energy of the particle. Thus the decrease of the particle's energy during the passage of the crystal should result in the destruction of the undulator radiation regime. However, we demonstrate that it is possible to avoid the destructive influence of the radiative losses on the frequency of the undulator radiation by the appropriate variation of the shape of the crystal channels. We also discuss a method by which, to our mind, it would be possible to prepare the crystal with the desired properties of its channels.
Paris-Sud XI, Université de
181 thorium en équilibre radioactif. Le thorium X donne le parcours 5 cm. 7, et l'émanation du thorium, pour laquelle on a été obligé d'employer une méthode de scintillations, le parcours 5,5 cm. Les parcours des rayions a émis par le thorium et ses produits sont réu- nis dans le tableau ci-contre, ou l
Start-to-end global imaging as a sunward propagating, SAPS-associated giant undulation event
Henderson, Michael G [Los Alamos National Laboratory; Donovan, Eric F [U OF CALGARY; Foster, John C [MIT; Mann, Ian R [UNIV OF ALBERTA; Immel, Thomas J [UC/BERKELEY; Mende, Stephen B [UN/BERKELEY; Sigwarth, John B [NASA/GSFC
2009-01-01T23:59:59.000Z
We present high-time resolution global imaging of a sunward propagating giant undulation event from start to finish. The event occurred on November 24, 2001 during a very disturbed storm interval. The giant undulations began to develop at around 13UT and persisted for approximately 2 hours. The sunward propagation speed was on the order of 0.6 km/s (relative to SM coordinate system). The undulations had a wavelength of {approx} 750 km, amplitudes of {approx} 890 km and produced ULF pulsations on the ground with a period of {approx} 1108s. We show that the undulations were associated with SAPs flows that were caused by the proton plasma sheet penetrating substantially farther Earthward than the electron plasma sheet on the duskside. The observations appear to be consistent with the development of a shear flow and/or ballooning type of instability at the plasmapause driven by intense SAPS-associated shear flows.
Off-Axis Undulator Radiation for CLIC Drive Beam Diagnostics
Jeff, A; Welsch, CP
2013-01-01T23:59:59.000Z
The Compact LInear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 1015 electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. In this paper we propose the use of relatively inexpensive permanent-magnet undulators to generate off-axis visible Synchrotron Radiation from the CLIC Drive Beam. The field strength and period length of the undulator should be designed such that the on-axis undulator wavelength is in the ultra-violet. A smaller but still useable amount of visible light is then generated in a hollow cone. This light can be reflected out of the beam pipe by a ring-shaped mirror placed downstream and imaged on a camera. In this contribution, results of SRW and ZEMA...
Fast pulsed excitation wiggler or undulator
van Steenbergen, Arie (Shoreham, NY)
1990-01-01T23:59:59.000Z
A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.
Positioning system for the LCLS undulator.
Trakhenberg, E. M.
2002-09-12T23:59:59.000Z
The Linac Coherent Light Source (LCLS) Project includes the undulator subsystem that has 33 undulator magnetic structures each 3.4 m long. Positioning of the LCLS undulators along the undulator line with an accuracy of 50 {micro}m in the vertical transverse direction is required. A prototype of the LCLS undulator has been built with a positioning system based on three stages with cam shafts. Each cam shaft produces reciprocating motion with a range of {+-}3 mm. A servomotor with integrated brake, incremental rotary encoder, servo amplifier, and controller is used with a 100:1 ratio gear box to drive each cam shaft. Resolution of the motion control is about 0.05 {micro}m. SmartMotors are connected in parallel through an RS-485 interface to the serial port of the computer. With this approach, the control system is easily expandable; up to 120 motors can be controlled with one serial port. Positioning accuracy of about 10 {micro}m for the LCLS undulator prototype is demonstrated.
Method of Linear Invariants for description of beam dynamics of FEL undulator
A. Angelow; D. Trifonov; V. Angelov; H. Hristov
2008-05-23T23:59:59.000Z
We propose a new model for description of electrons beam dynamics in Free Electron Laser (FEL) undulator, based on the method of linear time-dependent invariants of quantum-mechanical charge particle. The magnetic field has periodic structure along the undulator. For this problem, described by time-dependent quadratic Hamiltonian, we obtain exact solution. The time-evolutions of the tree quantum fluctuations: covariance cov(q,p), var(q) and var(p) for the charge particle in this case are also determined. This research will help to optimize the FEL undulator: for example, using a 2.5 GeV linear electron accelerator it will be possible to emit radiation at 1.5 nm and shorter length. This method could be applicable also to any device with periodic structure of applied field (e.g. Tokamak, cyclic accelerators) for the case of charge non-relativistic quantum particles.
Coherent Radiation Effects in the LCLS Undulator
Reiche, S.; /UCLA; Huang, Z.; /SLAC
2010-12-14T23:59:59.000Z
For X-ray Free-Electron Lasers such as LCLS and TESLA FEL, a change in the electron energy while amplifying the FEL radiation can shift the resonance condition out of the bandwidth of the FEL. The largest sources of energy loss is the emission of incoherent undulator radiation. Because the loss per electron depends only on the undulator parameters and the beam energy, which are fixed for a given resonant wavelength, the average energy loss can be compensated for by a fixed taper of the undulator. Coherent radiation has a strong enhancement proportional to the number of electrons in the bunch for frequencies comparable to or longer than the bunch dimension. If the emitted coherent energy becomes comparable to that of the incoherent emission, it has to be included in the taper as well. However, the coherent loss depends on the bunch charge and the applied compression scheme and a change of these parameters would require a change of the taper. This imposes a limitation on the practical operation of Free-Electron Lasers, where the taper can only be adjusted manually. In this presentation we analyze the coherent emission of undulator radiation and transition undulator radiation for LCLS, and estimate whether the resulting energy losses are significant for the operation of LCLS.
Undulator Hall Air Temperature Fault Scenarios
Sevilla, J.; Welch, J.; /SLAC; ,
2010-11-17T23:59:59.000Z
Recent experience indicates that the LCLS undulator segments must not, at any time following tuning, be allowed to change temperature by more than about {+-}2.5 C or the magnetic center will irreversibly shift outside of acceptable tolerances. This vulnerability raises a concern that under fault conditions the ambient temperature in the Undulator Hall might go outside of the safe range and potentially could require removal and retuning of all the segments. In this note we estimate changes that can be expected in the Undulator Hall air temperature for three fault scenarios: (1) System-wide power failure; (2) Heating Ventilation and Air Conditioning (HVAC) system shutdown; and (3) HVAC system temperature regulation fault. We find that for either a system-wide power failure or an HVAC system shutdown (with the technical equipment left on), the short-term temperature changes of the air would be modest due to the ability of the walls and floor to act as a heat ballast. No action would be needed to protect the undulator system in the event of a system-wide power failure. Some action to adjust the heat balance, in the case of the HVAC power failure with the equipment left on, might be desirable but is not required. On the other hand, a temperature regulation failure of the HVAC system can quickly cause large excursions in air temperature and prompt action would be required to avoid damage to the undulator system.
Planar Undulator Considerations(LCC-0085)
Sheppard, J
2003-10-07T23:59:59.000Z
This note consists of informal working notes that document an effort to understand the TESLA baseline, unpolarized, undulator based positron source. This is the first step in the design process of an undulator based positron system for the NLC. The expressions and methodologies developed herein are used in subsequent memos that reference this note. In regards to the TESLA design, it is found that a 135 m long (versus 100 m length) undulator is consistent with the performance descriptions in the TDR text. And while operation of the TESLA system with a 250 GeV drive beam energy provides a safety margin of a factor of {approx}2 in e{sup +} yield, operation of the same system at 160 GeV results in a yield of about 0.6.
Optical Fibre Dosimeter for SASE FEL Undulators
Körfer, M
2003-01-01T23:59:59.000Z
Single pass Free Electron Lasers (FELs) based on self-amplified spontaneous emission (SASE) are developed for high brightness and short wavelength applications. They use permanent magnet undulators which are radiation sensitive devices. During accelerator commissioning beam losses can appear anywhere along the undulator line. To avoid damage of the permanent magnets due to radiation, an optical fibre dosimeter system can be used. The increase of absorption caused by ionizing radiation is measured in radiation sensitive optical fibers. The dose system enables relatively fast particle loss tuning during accelerator operation and allows the monitoring of the accumulated dose. Dose measurements in narrow gaps which are inaccessible for any other (online) dosimeter type become possible. The electromagnetic insensitivity of optical fibre sensor is an advantage of applications in strong magnetic undulator fields. At each location the light absorption is measured by using an optical power-meter. The dynamic range is ...
Generation and characterization of superradiant undulator radiation
Bocek, D.
1997-06-01T23:59:59.000Z
High-power, pulsed, coherent, far-infrared (FIR) radiation has many scientific applications, such as pump-probe studies of surfaces, liquids, and solids, studies of high-T{sub c} superconductors, biophysics, plasma diagnostics, and excitation of Rydberg atoms. Few sources of such FIR radiation currently exist. Superradiant undulator radiation produced at the SUNSHINE (Stanford UNiversity SHort INtense Electron-source) is such a FIR source. First proposed in the mm-wave spectral range by Motz, superradiant undulator radiation has been realized in the 45 {micro}m to 300 {micro}m spectral range by using sub-picosecond electron bunches produced by the SUNSHINE facility. The experimental setup and measurements of this FIR radiation are reported in this thesis. In addition, to being a useful FIR source, the superradiant undulator radiation produced at SUNSHINE is an object of research in itself. Measured superlinear growth of the radiated energy along the undulator demonstrates the self-amplification of radiation by the electron bunch. This superlinear growth is seen at 47 {micro}m to 70 {micro}m wavelengths. These wavelengths are an order of magnitude shorter than in previous self-amplification demonstrations.
Plettner, T; Byer, R.L.; /Stanford U., Ginzton Lab.
2011-09-16T23:59:59.000Z
This article presents the concept of an all-dielectric laser-driven undulator for the generation of coherent X-rays. The proposed laser-driven undulator is expected to produce internal deflection forces equivalent to a several-Tesla magnetic field acting on a speed-of-light particle. The key idea for this laser-driven undulator is its ability to provide phase synchronicity between the deflection force and the electron beam for a distance that is much greater than the laser wavelength. The potential advantage of this undulator is illustrated with a possible design example that assumes a small laser accelerator which delivers a 2 GeV, 1 pC, 1 kHz electron bunch train to a 10 cm long, 1/2 mm period laser-driven undulator. Such an undulator could produce coherent X-ray pulses with {approx}10{sup 9} photons of 64 keV energy. The numerical modeling for the expected X-ray pulse shape was performed with GENESIS, which predicts X-ray pulse durations in the few-attosecond range. Possible applications for nonlinear electromagnetic effects from these X-ray pulses are briefly discussed.
UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC
Bakeman, M.S.
2010-01-01T23:59:59.000Z
ACCELERATOR ELECTRON BEAM DIAGNOSTIC* M.S. Bakeman # , W.M.of an undulator-based electron beam diagnostic to be used in
Tapering studies for Terawatt level X-ray FELs with a superconducting undulator
Emma, Claudio; Emma, Paul; Huang, Zhirong; Pellegrini, Claudio
2015-01-01T23:59:59.000Z
We study the tapering optimization scheme for a short period, less than two cm, superconducting undulator, and show that it can generate 4 keV X-ray pulses with peak power in excess of 1 terawatt, using LCLS electron beam parameters. We study the e?ect of undulator module length relative to the FEL gain length for continous and step-wise taper pro?les. For the optimal section length of 1.5m we study the evolution of the FEL process for two di?erent superconducting technologies NbTi and Nb3Sn. We discuss the major factors limiting the maximum output power, particle detrapping around the saturation location and time dependent detrapping due to generation and ampli?cation of sideband modes.
Anania, M. P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); INFN, Laboratori Nazionali di Frascati, I-00044 Frascati (Italy); Brunetti, E.; Wiggins, S. M.; Grant, D. W.; Welsh, G. H.; Issac, R. C.; Cipiccia, S.; Shanks, R. P.; Manahan, G. G.; Aniculaesei, C.; Jaroszynski, D. A., E-mail: d.a.jaroszynski@strath.ac.uk [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Geer, S. B. van der; Loos, M. J. de [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands); Poole, M. W.; Shepherd, B. J. A.; Clarke, J. A. [ASTeC, STFC, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Gillespie, W. A. [SUPA, School of Engineering, Physics and Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); MacLeod, A. M. [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee DD1 1HG (United Kingdom)
2014-06-30T23:59:59.000Z
Narrow band undulator radiation tuneable over the wavelength range of 150–260?nm has been produced by short electron bunches from a 2?mm long laser plasma wakefield accelerator based on a 20?TW femtosecond laser system. The number of photons measured is up to 9?×?10{sup 6} per shot for a 100 period undulator, with a mean peak brilliance of 1?×?10{sup 18} photons/s/mrad{sup 2}/mm{sup 2}/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130?MeV with the radiation pulse duration in the range of 50–100 fs.
The equivalence of inverse Compton scattering and the undulator concept
Ng, K.Y,; /Fermilab
2009-08-01T23:59:59.000Z
Inverse Compton scattering is a method to produce very high frequency photon beam. However, the production mechanism can also be viewed as a undulator emission. This is because the electron sees electric and magnetic fields of the incident laser beam and is driven into transverse oscillatory motion in exactly the same way when the electron passes through a undulator consisting of alternating magnetic field. This note gives a detailed examination of the similarity about the two views. Equivalent undulator parameters are derived for the incident laser beam, as well as the differential cross section of photon emission.
Earth's Magnetic Field Measurements for the LCLS Undulators
Hacker, Kirsten
2010-12-13T23:59:59.000Z
Measurements of the earth's magnetic field at several locations at SLAC were conducted to determine the possible field error contribution from tuning the undulators in a location with a different magnetic field than that which will be found in the undulator hall. An average difference of 0.08 {+-} 0.04 Gauss has been measured between the downward earth's field components in the test facility and SLAC tunnel locations.
Solomon, L.
1998-05-01T23:59:59.000Z
Measurements of the multipole content of the Mini-Undulator magnet have been made with two different integrating wire techniques. Both measurements used 43 strand Litz wire stretched along the length of the magnet within the magnet gap. In the first technique, the wire motion was purely translational, while in the second technique the wire was moved along a circular path. The induced voltage in the Litz wire was input into a Walker integrator, and the integrator output was analyzed as a function of wire position for determination of the multipole content of the magnetic field. The mini-undulator magnet is a 10 period, 80 mm per period hybrid insertion device. For all the data contained herein the magnet gap was set at 49 mm. In the mini-undulator magnet, the iron poles are 18mm x 32mm x 86 mm, and the Samarium Cobalt permanent magnet blocks are 22mm x 21mm x 110mm. For this magnet, which is a shortened prototype for the NSLS Soft X-Ray Undulator Magnet, the undulator parameter K = 0.934 B (Tesla){lambda}(cm), and B(tesla) = 0.534/sinh({pi}Gap/{lambda}). At a gap of 49 mm, the magnetic field is 1590 Gauss.
Solomon, L.; Ingold, G.; Ben-Zvi, I.; Krinsky, S.; Yu, L.H.; Sampson, W.; Robins, K.
1993-07-01T23:59:59.000Z
An 18mm period, 0.54 Tesla, 8mm gap superconducting undulator with both horizontal and vertical focusing has been built and tested. This magnet, which is fabricated in 25 cm length sections, is being tested for use in the radiator section (total magnet length of 1.5 m) of the Harmonic Generation Free Electron Laser experiment at the National Synchrotron Light Source - Accelerator Test Facility at Brookhaven National Lab., in collaboration with Grumman Corp. The measurement system is outlined, sources and estimates of errors are described, and some magnetic field data are presented and discussed.
Resistive Wall Heating of the Undulator in High Repetition Rate
Qiang, J; Corlett, J; Emma, P; Wu, J
2012-05-20T23:59:59.000Z
In next generation high repetition rate FELs, beam energy loss due to resistive wall wakefields will produce significant amount of heat. The heat load for a superconducting undulator (operating at low temperature), must be removed and will be expensive to remove. In this paper, we study this effect in an undulator proposed for a Next Generation Light Source (NGLS) at LBNL. We benchmark our calculations with measurements at the LCLS and carry out detailed parameter studies using beam from a start-to-end simulation. Our preliminarym results suggest that the heat load in the undulator is about 2 W/m or lower with an aperture size of 6 mm for nominal NGLS preliminary design parameters.
Nd-Fe-B Undulator Design for CES~ G. K. Shenoy, P. J. Viccaro...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
9 to 15 keV should be 10 16 to 10 17 at least photonssec0.17.BWmrad 2 mm 2 3 Optimization of Undulator Parameters Undulators can provide a very bright, quasi-monochromatic...
Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic
Bakeman, M.S.
2011-01-01T23:59:59.000Z
Accelerator, Undulator, Electron Beam Diagnostic PACS: 52 .of an undulator-based electron beam diagnostic to be used inElectron Beam Energy Spread and Emittance Diagnostic M.S.
Proposed dielectric-based microstructure laser-driven undulator T. Plettner and R. L. Byer
Byer, Robert L.
sources that feed into permanent-magnet undulators. The distinguish- ing feature of the undulator proposed a proposed all-dielectric laser-driven undulator for the generation of coherent short wavelengths and explore-electron radiation concepts for ultrashort coherent wavelength generation are being investigated. For example, active
The LCLS Undulator Beam Loss Monitor Readout System
Dusatko, John; Browne, M.; Fisher, A.S.; Kotturi, D.; Norum, S.; Olsen, J.; /SLAC
2012-07-23T23:59:59.000Z
The LCLS Undulator Beam Loss Monitor System is required to detect any loss radiation seen by the FEL undulators. The undulator segments consist of permanent magnets which are very sensitive to radiation damage. The operational goal is to keep demagnetization below 0.01% over the life of the LCLS. The BLM system is designed to help achieve this goal by detecting any loss radiation and indicating a fault condition if the radiation level exceeds a certain threshold. Upon reception of this fault signal, the LCLS Machine Protection System takes appropriate action by either halting or rate limiting the beam. The BLM detector consists of a PMT coupled to a Cherenkov radiator located near the upstream end of each undulator segment. There are 33 BLMs in the system, one per segment. The detectors are read out by a dedicated system that is integrated directly into the LCLS MPS. The BLM readout system provides monitoring of radiation levels, computation of integrated doses, detection of radiation excursions beyond set thresholds, fault reporting and control of BLM system functions. This paper describes the design, construction and operational performance of the BLM readout system.
Triggering for Magnetic Field Measurements of the LCLS Undulators
Hacker, Kirsten
2010-12-13T23:59:59.000Z
A triggering system for magnetic field measurements of the LCLS undulators has been built with a National Instruments PXI-1002 and a Xylinx FPGA board. The system generates single triggers at specified positions, regardless of encoder sensor jitter about a linear scale.
High-gain X-ray free electron laser by beat-wave terahertz undulator
Chang, Chao; Hei, DongWei [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an City 710024 (China) [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an City 710024 (China); Institute of Energy, Tsinghua University, Beijing 100084 (China); Pellegrin, Claudio; Tantawi, Sami [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States)] [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States)
2013-12-15T23:59:59.000Z
The THz undulator has a higher gain to realize a much brighter X-ray at saturation, compared with the optical undulator under the same undulator strength and beam quality. In order to fill the high-power THz gap and realize the THz undulator, two superimposed laser pulses at normal incidence to the electron-beam moving direction form an equivalent high-field THz undulator by the frequency difference to realize the high-gain X-ray Free electron laser. The pulse front tilt of lateral fed lasers is used to realize the electron-laser synchronic interaction. By PIC simulation, a higher gain and a larger X-ray radiation power by the beat wave THz undulator could be realized, compared with the optical undulator for the same electron beam parameters.
Elias, N; Dalexandro, N; Giloux, C; Bordini, B; Maccaferri, R
2010-01-01T23:59:59.000Z
The future run of the Large Hadron Collider with lead ions will require important modifications in the synchrotron radiation profile monitor system, which at present comprises two superconducting undulators wound from Nb-Ti conductor, delivering 5 T in a 60 mm gap, and with a period of 280 mm. Whilst the gap and the nominal field of the future undulators will remain the same, the period shall be 140 mm, which translates to a peak field of over 8 T in the coils and hence requires the use of Nb3Sn technology. In this paper the electromagnetic design of the undulator is summarized. We describe the fabrication of a race-track coil wound with a 0.8 mm diameter Nb3Sn strand with ceramic insulation. Finally, the results of successful tests made at 4.3 K and 1.9 K in a mirror configuration are presented. 10 T at 4.3 K and 11.5 T at 1.9 K were measured in the yoke gap, thus validating this concept for the future undulator.
Investigation of a 2-Colour Undulator FEL Using Puffin
Campbell, L T; Reiche, S
2013-01-01T23:59:59.000Z
Initial studies of a 2-colour FEL amplifier using one monoenergetic electron beam are presented. The interaction is modelled using the unaveraged, broadband FEL code Puffin. A series of undulator modules are tuned to generate two resonant frequencies along the FEL interaction and a self-consistent 2-colour FEL interaction at widely spaced non-harmonic wavelengths at 1nm and 2.4nm is demonstrated.
Undulator radiation simulation tools in view of proton beam diagnostics in LHC
Ponce, L; CERN. Geneva. SPS and LHC Division
2001-01-01T23:59:59.000Z
As a superconducting undulator is planned to be used for beam diagnostics in LHC, it appeared to be necessary to adapt the simulation tools. Hence, a new procedure UNDULATOR has been implemented in the ray-tracing code Zgoubi and is assessed in this paper. After a brief recall of the numerical methods of concern, some simulations with UNDULATOR are compared, first with classical analytical models and then with field map based methods using the procedure TOSCA.
Production of Ultrashort FEL XUV Pulses via a Reverse Undulator Taper
Fawley, William M.
2007-01-01T23:59:59.000Z
Production of Ultrashort FEL XUV Pulses via a Reverseof 2009. In recent years, FEL researchers have explored ara- diator undulators, the FEL emission will predomi- nately
Radiological Considerations in the Operation of the Low-Energy Undulator Test Line (LEUTL)
Kemner, Ken
1 Radiological Considerations in the Operation of the Low-Energy Undulator Test Line (LEUTL) April 10, 1998 H. J. Moe 1. General The Low-Energy Undulator Test Line (LEUTL) is a facility that uses dump. This facility is about 51 m long and 3.66 m wide. Technical compo- nents and diagnostics
Chubar, O V; Couprie, M E; Filhol, J M; Leroy, E; Marteau, F; Paulin, F; Rudenko, O
2008-01-01T23:59:59.000Z
Compensation of Variable Skew- and Normal quadrupole Focusing Effects of APPLE-II Undulators with Computer-aided Shimming
Cryogenic performance of a cryocooler-cooled superconducting undulator
Fuerst, J. D.; Doose, C.; Hasse, Q.; Ivanyushenkov, Y.; Kasa, M.; Shiroyanagi, Y. [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)
2014-01-29T23:59:59.000Z
A cryocooler-cooled superconducting undulator has been installed and operated with beam at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The device consists of a dual-core 42-pole magnet structure that is cooled to 4.2 K with a system of four cryocoolers operating in a zero-boil-off configuration. This effort represents the culmination of a development program to establish concept feasibility and evaluate cryostat design and cryocooler-based refrigeration. Cryostat performance is described including cool-down/warm-up, steady-state operation, cooling margin, and the impact of beam during operation in the APS storage ring. Plans for future devices with longer magnets, which will incorporate lessons learned from the development program, are also discussed.
Geloni, Gianluca; Saldin, Evgeni
2015-01-01T23:59:59.000Z
We show that radiation pulses from an X-ray Free-Electron Laser (XFEL) with a planar undulator, which are mainly polarized in the horizontal direction, exhibit a suppression of the vertical polarization component of the power at least by a factor $\\lambda_w^2/(4 \\pi L_g)^2$, where $\\lambda_w$ is the length of the undulator period and $L_g$ is the FEL field gain length. We illustrate this fact by examining the XFEL operation under the steady state assumption. In our calculations we considered only resonance terms: in fact, non resonance terms are suppressed by a factor $\\lambda_w^3/(4 \\pi L_g)^3$ and can be neglected. While finding a situation for making quantitative comparison between analytical and experimental results may not be straightforward, the qualitative aspects of the suppression of the vertical polarization rate at XFELs should be easy to observe. We remark that our exact results can potentially be useful to developers of new generation FEL codes for cross-checking their results.
Delta undulator test result and specific of a small bore insertion...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Delta undulator magnet beam test at ATF (BNL) *Work has been supported by NSF grant DMR 0225180 and PHY- 013150 and supported by DOE Office of Science M. Babzien, D. Davis, M....
SOLOMON, L.
1998-05-01T23:59:59.000Z
Measurements of the multipole content of the Mini-Undulator magnet have been made with two different integrating wire techniques. Both measurements used 43 strand Litz wire stretched along the length of the magnet within the magnet gap. In the first technique, the wire motion was purely translational, while in the second technique the wire was moved along a circular path. The induced voltage in the Litz wire was input into a Walker integrator, and the integrator output was analyzed as a function of wire position for determination of the multipole content of the magnetic field. The mini-undulator magnet is a 10 period, 80 mm per period hybrid insertion device. For all the data contained herein the magnet gap was set at 49 mm. In the mini-undulator magnet, the iron poles are 18mm x 32mm x 86mm, and the Samarium Cobalt permanent magnet blocks are 22mm x 21mm x 110mm. For this magnet, which is a shortened prototype for the NSLS Soft X-Ray Undulator Magnet, the undulator parameter K = 0.934 B(Tesla){lambda}(cm), and B(tesla) = 0.534/sinh({pi}Gap/{lambda}). At a gap of 49 mm, the magnetic field is 1590 Gauss. The 43 strand Litz wire is supported on motorized x-y stages at both ends of the magnet, which are controlled by stepping motors through a Labview program. One leg of the wire loop is within the magnet gap, and the other leg is in an essentially field free region. Only the leg of the wire loop within the magnet gap is moved during data acquisition. The Litz wire is tensioned with 11.5 pounds, and is wrapped with a supporting tape which is itself tensioned with 18 pounds through a spring and turnbuckle arrangement. With this setup the sag in the wire over the 72 inch span is less than 0.003 inches, as measured with survey instruments. Photographs of the setup are shown.
Fabrication of a Short-Period Nb3Sn Superconducting Undulator
Dietderich, Daniel
2008-01-01T23:59:59.000Z
Trans. on Applied Superconductivity, Vol. 13, No. 2, pp.Trans. on Applied Superconductivity, MT-19, June 2005. [7]Trans. on Applied Superconductivity, vol. 15, no. 2, 2005,
Orbit Correction for the Newly Developed Polarization-Switching Undulator
Obina, Takashi; Honda, Tohru; Shioya, Tatsuro; Kobayashi, Yukinori; Tsuchiya, Kimichika [Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yamamoto, Shigeru [Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Department of Photoscience, Graduate University for Advanced Studies, Shonan Village, Hayama, Kanagawa 240-0193 (Japan)
2007-01-19T23:59:59.000Z
A new scheme of undulator magnet arrangements has been proposed and developed as a polarization-switching radiation source, and its test-stand was installed in the 2.5-GeV Photon Factory storage ring (PF ring) in order to investigate the effects on the beam orbit. The closed orbit distortion (COD) over 200 {mu}m was produced in a vertical direction when we switched the polarization of the radiation from the test-stand. In a horizontal direction, the COD was less than 50{mu}m. The results agreed well with the predictions from the magnetic-field measurement on the bench. In order to suppress the CODs and realize a stable operation of the ring with the polarization-switching, we developed an orbit correction system which consists of an encoder to detect motion of magnets, a pair of beam position monitors (BPMs), signal processing parts, and a pair of steering magnets. We succeeded in suppressing the CODs to the level below 3{mu}m using the system even when we switch the polarization at a maximum frequency of 0.8 Hz.
Undulation Amplitude of a Fluid Membrane Surrounded by Near-Critical Binary Fluid Mixtures
Youhei Fujitani
2014-12-22T23:59:59.000Z
We consider the thermal undulation, or shape fluctuation, of an almost planar fluid membrane surrounded by the same near-critical binary fluid mixtures on both sides. A weak preferential attraction is assumed between the membrane and one component of the mixture. We use the Gaussian free-energy functional to study the equilibrium average of the undulation amplitude within the linear approximation with respect to the amplitude. According to our result given by a simple analytic formula, the ambient near-criticality tends to suppress the undulation of a membrane without the lateral tension. This suppression effect can overwhelm that of the bending rigidity for small wave numbers. Thus, the ambient near-criticality can prevent a large membrane from becoming floppy even if it has no lateral tension.
Polarization Analysis for Seeded FELs in a Crossed-Planar Undulator
Geng, Huiping; /SLAC; Ding, Yuantao; /SLAC; Huang, Zhirong; /SLAC; Bartolini, Riccardo; /Diamond Light Source; Dunning, David; /Daresbury; Thompson, Neil; /Daresbury
2012-06-25T23:59:59.000Z
The crossed-planar undulator is a promising scheme for full polarization control in x-ray FELs. For SASE FELs, it has been shown a maximum degree of circular polarization of about 80% is achievable at fundamental wavelength just before saturation. In this paper, we study the effectiveness of a crossed undulator for a seeded x-ray FEL. The degree of circular polarization for both the fundamental and the harmonic radiation are considered. Simulations with realistic beam distributions show that a degree of circular polarization of over 90% and 80% is obtainable at the fundamental and 2nd harmonic frequencies, respectively.
Knot undulator to generate linearly polarized photons with low on-axis power density
Qiao, S; Feng, Donglai; Hussain, Z; Shen, Z -X
2008-01-01T23:59:59.000Z
Heat load on beamline optics is a serious problem to generate pure linearly polarized photons in the third generation synchrotron radiation facilities. For permanent magnet undulators, this problem can be overcome by a figure-8 operating mode. But there is still no good method to tackle this problem for electromagnetic elliptical undulators. Here, a novel operating mode is suggested, which can generate pure linearly polarized photons with very low on-axis heat load. Also the available minimum photon energy of linearly polarized photons can be extended much by this method.
Cyclotron-undulator cooling of a free-electron-laser beam
Bandurkin, I. V.; Kuzikov, S. V. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Savilov, A. V. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod (Russian Federation)
2014-08-18T23:59:59.000Z
We propose methods of fast cooling of an electron beam, which are based on wiggling of particles in an undulator in the presence of an axial magnetic field. We use a strong dependence of the axial electron velocity on the oscillatory velocity, when the electron cyclotron frequency is close to the frequency of electron wiggling in the undulator field. The abnormal character of this dependence (when the oscillatory velocity increases with the increase of the input axial velocity) can be a basis of various methods for fast cooling of moderately relativistic (several MeV) electron beams.
MEMS multi-pole electromagnets: Compact electron optics and undulators
Harrison, Jere Charles
2014-01-01T23:59:59.000Z
electron laser system using MEMS optics . . . . . . . . .power soft x-ray source based on a 400-µm period MEMS un-micrograph of a MEMS ‘racetrack’ transformer. . . . . . .
Conceptual Design of a Helical Undulator for a TESLA SASE FEL
Vat an electronenergyof 23 GeV.The design is based on the technology of the BESSY II helical devices. Other technologies might be also applicable but will not be considered here. At BESSY II two helical double undulators of circularly polarized light in many laboratories (ALS, BESSY, ELETTRA, ESRF, PLS, SPRING 8, SRRC, SSRL
Determination of Electron Density Profiles and Area from Simulations of Undulating Membranes
Nagle, John F.
Supporting Material Anthony R. Braun1 , Erik G. Brandt2 , Olle Edholm2 , John F. Nagle3 and Jonathan N. Sachs;Undulations in bilayer structure 2 I. Simulation details The atomic coordinates of crystalline 1,2-dimyristoyl-sn
Manufacturing Considerations of the Magnetic Structures for the Undulators for the X-FEL at TESLA
1 Manufacturing Considerations of the Magnetic Structures for the Undulators for the X-FEL at TESLA DESY / HASYLAB Notkestr. 85, 22607 Hamburg, Germany TESLA-FEL 2000-10 Abstract A study is presented FELs. The total magnetic length of the magnet structures is 1405m. It is proposed to produce these huge
Field Accuracy Requirements for the Undulator Systems of the X-ray FEL's at TESLA
Field Accuracy Requirements for the Undulator Systems of the X-ray FEL's at TESLA B. Faatz, J. 85, 22607 Hamburg, Germany Abstract In SASE FELs, the radiation power has to saturate in a single. The influence of the electron beam quality has been studied in detail in many papers. For the TESLA X-ray FEL
Field Enhancement of a Superconducting Helical Undulator with K. Flttmann, S.G. Wipf
. Geometry of a helical undulator with iron A helical field can be produced by a pair of conductors wound to form a double helix as sketched in Figure 1. The current in the two conductors is equal and of opposite of the coil ro= outer radius of the coil B = on axis field amplitude (1) A width of 1/3 is assumed
High precision measurement of undulator polarization in the regime of hard x-rays
Marx, B., E-mail: berit.marx@uni-jena.de [Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Schulze, K. S.; Uschmann, I.; Kämpfer, T.; Wehrhan, O.; Förster, E.; Paulus, G. G. [Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Helmholtz-Institut Jena, Fröbelstieg 3, D-07743 Jena (Germany); Wille, H. C.; Schlage, K.; Röhlsberger, R.; Weckert, E. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg (Germany); Stöhlker, T. [Helmholtz-Institut Jena, Fröbelstieg 3, D-07743 Jena (Germany)
2014-07-14T23:59:59.000Z
We have measured the polarization purity of undulator radiation at 12.9?keV, with hitherto unachievable precision. We could measure a polarization purity of 1.8?×?10{sup ?4} by using a silicon channel-cut crystal with six Bragg reflections at 45° as analyzer.
Energy Loss and Energy Spread Growth in a Planar Undulator(LCC-0086)
Sheppard, J
2003-10-07T23:59:59.000Z
The change in beam energy spread due to transmission through a long, planar undulator is calculated. This change is shown to be gaussian as expected from the central limit theorem and large number of photons emitted per electron. These results are compared with Saldin et al. [2] expressions. Numerical results for the case of the TESLA beam and for an NLC beam are given.
Application of Genetic Algorithms to Sorting, Swapping and Shimming of the SOLEIL Undulator Magnets
Chubar, O.; Rudenko, O.; Benabderrahmane, C.; Marcouille, O.; Filhol, J. M.; Couprie, M. E. [Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin - BP 48, 91192 GIF-sur-YVETTE CEDEX (France)
2007-01-19T23:59:59.000Z
Undulators are typically composed of a large number of individual magnets, from tens to many hundreds, depending on undulator type and technology. Characteristics of real magnets often deviate from ideal values, resulting in degradation of the undulator performance. It is known that the imperfections of individual magnets can be mutually compensated, to certain extent, by appropriate sorting of the magnets and/or magnet modules, based on measurements of their individual characteristics, performed before the insertion device (ID) assembly. After the assembly, the quality of the ID magnetic field can be improved by magnet swapping and by shimming, consisting either in small displacements of some of the magnets or in adding small pieces of permanent magnet or soft iron material to appropriate locations of the structure. Mathematically, the magnet sorting, swapping and shimming can be considered as multi-objective constrained optimization problems with large numbers of variables. We show that each of these problems can be efficiently solved by means of Genetic Algorithms with 3D magnetostatics methods and magnetic measurements data used for the fitness calculation. First practical results obtained with three different undulators of the SOLEIL Synchrotron are presented.
A simple model based magnet sorting algorithm for planar hybrid undulators
Rakowsky, G.
2010-05-23T23:59:59.000Z
Various magnet sorting strategies have been used to optimize undulator performance, ranging from intuitive pairing of high- and low-strength magnets, to full 3D FEM simulation with 3-axis Helmholtz coil magnet data. In the extreme, swapping magnets in a full field model to minimize trajectory wander and rms phase error can be time consuming. This paper presents a simpler approach, extending the field error signature concept to obtain trajectory displacement, kick angle and phase error signatures for each component of magnetization error from a Radia model of a short hybrid-PM undulator. We demonstrate that steering errors and phase errors are essentially decoupled and scalable from measured X, Y and Z components of magnetization. Then, for any given sequence of magnets, rms trajectory and phase errors are obtained from simple cumulative sums of the scaled displacements and phase errors. The cost function (a weighted sum of these errors) is then minimized by swapping magnets, using one's favorite optimization algorithm. This approach was applied recently at NSLS to a short in-vacuum undulator, which required no subsequent trajectory or phase shimming. Trajectory and phase signatures are also obtained for some mechanical errors, to guide 'virtual shimming' and specifying mechanical tolerances. Some simple inhomogeneities are modeled to assess their error contributions.
Canted Undulator Upgrade for GeoSoilEnviroCARS Sector 13 at the Advanced Photon Source
Sutton, Stephen
2013-02-02T23:59:59.000Z
Support for the beamline component of the canted undulator upgrade of Sector 13 (GeoSoilEnviroCARS; managed and operated by the University of Chicago) at the Advanced Photon Source (APS; Argonne National Laboratory) was received from three agencies (equally divided): NASA-SRLIDAP (now LARS), NSF-EAR-IF (ARRA) and DOE-Single Investigator Small Group (SISGR). The associated accelerator components (undulators, canted front end) were provided by the APS using DOE-ARRA funding. The intellectual merit of the research enabled by the upgrade lies in advancing our knowledge of the composition, structure and properties of earth materials; the processes they control; and the processes that produce them. The upgrade will facilitate scientific advances in the following areas: high pressure mineral physics and chemistry, non-crystalline and nano-crystalline materials at high pressure, chemistry of hydrothermal fluids, reactions at mineral-water interfaces, biogeochemistry, oxidation states of magmas, flow dynamics of fluids and solids, and cosmochemistry. The upgrade, allowing the microprobe to operate 100% of the time and the high pressure and surface scattering and spectroscopy instruments to receive beam time increases, will facilitate much more efficient use of the substantial investment in these instruments. The broad scientific community will benefit by the increase in the number of scientists who conduct cutting-edge research at GSECARS. The user program in stations 13ID-C (interface scattering) and 13ID-D (laser heated diamond anvil cell and large volume press) recommenced in June 2012. The operation of the 13ID-E microprobe station began in the Fall 2012 cycle (Oct.-Dec 2012). The upgraded canted beamlines double the amount of undulator beam time at Sector 13 and provide new capabilities including extended operations of the X-ray microprobe down to the sulfur K edge and enhanced brightness at high energy. The availability of the upgraded beamlines will advance the research being conducted at Sector 13.
NOVEL CHAMBER DESIGN FOR AN IN-VACUUM CRYO-COOLED MINI-GAP UNDULATOR.
HU, J.-P.; FOERSTER, C.L.; SKARITKA, J.R.; WATERMAN, D.
2006-05-24T23:59:59.000Z
A stainless steel, Ultra-High Vacuum (UHV) chamber, featuring a large vertical rectangular port (53''W by 16''H), has been fabricated to house the one-meter magnet assembly of a newly installed undulator insertion device for beamline X-25 at the National Synchrotron Light Source. To achieve UHV, the new chamber is equipped with a differential ion pump, NEG pump, nude ion gauge, residual gas analyzer, and an all metal roughing valve. Temperature of the magnet assembly is maintained below 90 C during vacuum bake. The large rectangular port cover is sealed to the main flange of the chamber using a one-piece flat aluminum gasket and special sealing surfaces developed exclusively by Nor-Cal Products, Inc. The large flange provides easy access to the gap of the installed magnet girders for in situ magnetic measurements and shimming. Special window ports were designed into the cover and chamber for manipulation of optical micrometers external to the chamber to provide precise measurements of the in-vacuum magnet gap. The vacuum chamber assembly features independently vacuum-isolated feedthroughs that can be used for either water-or-cryogenic refrigeration-cooling of the monolithic magnet girders. This would allow for cryogenic-cooled permanent magnet operation and has been successfully tested within temperature range of +100 C to -150 C. Details of the undulator assembly for beamline X-25 is described in the paper.
Homes, Christopher C.
generationof soft x-ray undulator beam lines which will figure prominently at new synchrotron radiation facilities such as ALS, ELETTRA and BESSY II. During the first performancetestsabsorption spectra of simple-ray region. 1. INTRODUCTION The next generationof synchrotron radiation (SR) fa- cilities servingthe soft x
sources of X-ray radiation. They constitute invaluable tools for a broad range of research1 ; however, their dependence on large- scale radiofrequency electron accelerators means that only a few of these sources exist-laboratory scale. Here, we demonstrate the generation of soft-X-ray undulator radiation with laser
Radiological considerations in the operation of the low-energy undulator test line (LEUTL).
Moe, H.J.
1998-11-11T23:59:59.000Z
The Low-Energy Undulator Test Line (LEUTL) is a facility that uses the existing APS linac to accelerate electrons up to an energy of 700 MeV. These electrons are transported through the Pm into a portion of the booster synchrotrons and on into the LEUTL main enclosure (MIL 97). Figure 1 shows the layout of the LEUTL building, which consists of an earth-benned concrete enclosure and an end-station building. The concrete enclosure houses the electron beamline, test undulator, and beam dump. This facility is about 51 m long and 3.66 m wide. Technical components and diagnostics for characterizing the undulator light are found in the end station. This building has about 111 m{sup 2} of floor space. This note deals with the radiological considerations of operations using electrons up to 700 MeV and at power levels up to the safety envelope of 1 kW. Previous radiological considerations for electron and positron operations in the linac, PAR, and synchrotrons have been addressed else-where (MOE 93a, 93b, and 93c). Much of the methodology discussed in the previous writeups, as well as in MOE 94, has been used in the computations in this note. The radiological aspects that are addressed include the following: prompt secondary radiation (bremsstrahlung, giant resonance neutrons, medium- and high-energy neutrons) produced by electrons interacting in a beam stop or in component structures; skyshine radiation, which produces a radiation field in nearby areas and at the nearest off-site location; radioactive gases produced by neutron irradiation of air in the vicinity of a particle loss site; noxious gases (ozone and others) produced in air by the escaping bremsstrahlung radiation that results from absorbing particles in the components; activation of the LEUTL components that results in a residual radiation field in the vicinity of these materials following shutdown; potential activation of water used for cooling the magnets and other purposes in the tunnel; and evaluation of the radiation fields due to escaping gas bremsstrahlung. Estimated dose rates have been computed or scaled (in the case of 400 MeV electrons) outside of the bermed tunnel, in Building 412, and in the Klystron Gallery for several modes of operation, including potential safety envelope beam power, normal beam power and MCI (maximum credible incident) conditions. Radiological aspects of shielding changes to the synchrotrons and their effect upon operations are addressed in MOE 97. No change in the safety envelope for synchrotrons operation was warranted.
Quantum effects in spontaneous emission by a relativistic, undulating electron beam
G. R. M. Robb; R. Bonifacio
2011-10-27T23:59:59.000Z
Current models of the effect of spontaneous emission on the electron beam dynamics neglect the discreteness of electron recoil associated with photon emission. We present a novel, one-dimensional model of the effect of spontaneous emission on the electron beam dynamics in an undulator both in the classical regime where discrete electron recoil is negligible, and the quantum regime where it is significant. It is shown that in the classical regime, continuous decrease of the average electron energy and diffusive growth of the electron energy spread occurs, in agreement with previous classical models. In the quantum regime, it is shown that the evolution of the electron momentum distribution occurs as discrete momentum groups according to a Poisson distribution. The narrow momentum features of the quantum regime may be useful for generation of coherent radiation, which relies on electron beams having sufficiently narrow momentum/energy distributions.
Hsieh, H.; Krinsky, S.; Luccio, A.; Pellegrini, C.; van Steenbergen, A.
1982-01-01T23:59:59.000Z
An overview is presented of the special radiation sources development at the NSLS for incorporation in a 2.5 GeV X-ray storage ring and a 700 MeV vuv storage ring. This includes a superconducting high field multipole wiggler, lambda/sub c/ = 0.5A; a permanent magnet wiggler, lambda/sub c/ = 2.0A; a maximum photon energy undulator (5 to 7 keV); an undulator for a soft X-ray line or continuum spectrum and a free electron laser source tunable in the 2500 to 4500A region. Source characteristics and status of development are given. In addition, the incorporation of a backscattered Compton photon source is being studied and relevant parameters are presented.
DESIGN OF 9 T 5 CM BORE DIPOLE
Taylor, C.E.
2010-01-01T23:59:59.000Z
diameter Twist Number strands Keystone angle Thickness Widthdiameter Twist Number strands Keystone angle Thickness Width
Schneidmiller, E A
2015-01-01T23:59:59.000Z
We describe statistical and coherence properties of the radiation from x-ray free electron lasers (XFEL) operating in the post-saturation regime. We consider practical case of the SASE3 FEL at the European XFEL. We perform comparison of the main characteristics of the X-ray FEL operating in the post-saturation regime with and without undulator tapering: efficiency, coherence time and degree of transverse coherence.
Tatchyn, Roman; /SLAC
2011-09-09T23:59:59.000Z
Insertion devices for Angstrom-wavelength Free Electron Laser (FEL) amplifiers driven by multi-GeV electron beams generally require distributed focusing substantially stronger than their own natural focusing fields. Over the last several years a wide variety of focusing schemes and configurations have been proposed for undulators of this class, ranging from conventional current-driven quadrupoles external to the undulator magnets to permanent magnet (PM) lattices inserted into the insertion device gap. In this paper we present design studies of a flexible high-field hybrid/PM undulator with strong superimposed planar PM focusing proposed for a 1.5 Angstrom Linac Coherent Light Source (LCLS) driven by an electron beam with a 1 mm-mr normalized emittance. Attainable field parameters, tuning modes, and potential applications of the proposed structure are discussed.
Park, So Yeong; Hong, Chung Ki [Department of Physics, POSTECH, Pohang 790-784 (Korea, Republic of)] [Department of Physics, POSTECH, Pohang 790-784 (Korea, Republic of); Lim, Jun, E-mail: limjun@postech.ac.kr [Pohang Accelerator Laboratory, POSTECH, Pohang 790-784 (Korea, Republic of)] [Pohang Accelerator Laboratory, POSTECH, Pohang 790-784 (Korea, Republic of)
2014-04-15T23:59:59.000Z
We measured the spatial coherence length and incoherent source size of a hard x-ray undulator beamline at Pohang Light Source-II, the stored electron energy of which has been increased from 2.5 GeV to 3 GeV. The coherence length was determined by single-slit measurement of the visibility of the Fresnel diffraction pattern. The correlated incoherent source size was cross-checked for three different optics: the single slit, beryllium parabolic compound refractive lenses, and the Fresnel zone plate. We concluded that the undulator beamline has an effective incoherent source size (FWHM) of 540 ?m (horizontal) × 50 ?m (vertical)
Beam Based Alignment of the TESLA X-ray FEL undulators B. Faatz Deutsches Elektronen the performance of the FEL is the overlap between electron beam and radiation field during the amplification The TESLA X-ray FEL laboratory is a proposed user facility in the wavelength range between ¼ Å and 6 nm
De-Xing Kong; Kefeng Liu; Ming Shen
2008-08-30T23:59:59.000Z
In this letter we construct a new time-periodic solution of the vacuum Einstein's field equations whose Riemann curvature norm takes the infinity at some points. We show that this solution is intrinsically time-periodic and describes a time-periodic universe with the "black hole". New physical phenomena are investigated and new singularities are analyzed for this universal model.
Mojzsis, Stephen J.
spectrograph home with you and look at eight light sources. Make sure to look at at least three different kinds, as straight as possible. Tape using masking tape so that no light leaks into the box aside from the light through the lid, and point your spectrograph at the light source. You should see a continuous spectrum (a
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
that may open and close by 100 m. There are no requirements on the integrated multipole moments, and there are no requirements to maintain a high radiation intensity for...
Genealogy of periodic trajectories
de Adguiar, M.A.M.; Maldta, C.P.; de Passos, E.J.V.
1986-05-20T23:59:59.000Z
The periodic solutions of non-integrable classical Hamiltonian systems with two degrees of freedom are numerically investigated. Curves of periodic families are given in plots of energy vs. period. Results are presented for this Hamiltonian: H = 1/2(p/sub x//sup 2/ + p/sub y//sup 2/) + 1/2 x/sup 2/ + 3/2 y/sup 2/ - x/sup 2/y + 1/12 x/sup 4/. Properties of the families of curves are pointed out. (LEW)
Fourier series and periodicity
Donal F. Connon
2014-12-07T23:59:59.000Z
A large number of the classical texts dealing with Fourier series more or less state that the hypothesis of periodicity is required for pointwise convergence. In this paper, we highlight the fact that this condition is not necessary.
Broader source: Energy.gov [DOE]
DOE has published a Final Environmental Impact Statement (EIS), and the 30-day waiting period has ended. DOE is preparing a Record of Decision to announce and explain its chosen project alternative...
PERIODIC WAVELET TRANSFORMS AND PERIODICITY JOHN J. BENEDETTO AND G
Benedetto, John J.
PERIODIC WAVELET TRANSFORMS AND PERIODICITY DETECTION JOHN J. BENEDETTO #3; AND G OTZ E. PFANDER y Key words. Continuous wavelet transform, epileptic seizure prediction, periodicity detection algorithm, optimal generalized Haar wavelets, wavelet frames on Z. AMS subject classi#12;cations. 42C99, 42C
G. R. M. Robb; R. Bonifacio
2012-03-12T23:59:59.000Z
In arXiv:1202.0691, Geloni et al. criticise our recent work describing the spontaneous emission by a relativistic, undulating electron beam. In particular they claim that our prediction of a quantum regime in which evolution of the electron momentum distribution occurs as a sequential population of discrete momentum groups rather than in terms of a drift-diffusion process is unphysical and artificial. We show that the criticism of our model contained in arXiv:1202.0691 is unfounded.
Representing Periodic Functions by Fourier
Vickers, James
Representing Periodic Functions by Fourier Series 23.2 Introduction In this Section we show how, then the Fourier series expansion takes the form: f(t) = a0 2 + n=1 (an cos nt + bn sin nt) Our main purpose here Fourier coefficients of a function of period 2 calculate Fourier coefficients of a function of general
Shortest recurrence periods of novae
Kato, Mariko [Department of Astronomy, Keio University, Hiyoshi, Yokohama 223-8521 (Japan); Saio, Hideyuki [Astronomical Institute, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Hachisu, Izumi [Department of Earth Science and Astronomy, College of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902 (Japan); Nomoto, Ken'ichi, E-mail: mariko@educ.cc.keio.ac.jp [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)
2014-10-01T23:59:59.000Z
Stimulated by the recent discovery of the 1 yr recurrence period nova M31N 2008-12a, we examined the shortest recurrence periods of hydrogen shell flashes on mass-accreting white dwarfs (WDs). We discuss the mechanism that yields a finite minimum recurrence period for a given WD mass. Calculating the unstable flashes for various WD masses and mass accretion rates, we identified a shortest recurrence period of about two months for a non-rotating 1.38 M {sub ?} WD with a mass accretion rate of 3.6 × 10{sup –7} M {sub ?} yr{sup –1}. A 1 yr recurrence period is realized for very massive (? 1.3 M {sub ?}) WDs with very high accretion rates (? 1.5 × 10{sup –7} M {sub ?} yr{sup –1}). We revised our stability limit of hydrogen shell burning, which will be useful for binary evolution calculations toward Type Ia supernovae.
Mechanics of planar periodic microstructures
Prange, Sharon M. (Sharon Marie)
2007-01-01T23:59:59.000Z
The deformation of two-dimensional periodically patterned elastomeric sheets has been shown to trigger interesting pattern changes that are both repeatable and predictable (Bertoldi et al., 2007). Here, both square and ...
Shechter, Guy; Resar, Jon R.; McVeigh, Elliot R. [Lab of Cardiac Energetics, NHLBI, NIH Building 10, Room B1D-412, msc-1061, Bethesda, Maryland 20892-1061 (United States); Division of Cardiology, Department of Medicine, Johns Hopkins University, 600 North Wolfe Street, Blalock 524B, Baltimore, Maryland 21287 (United States); Lab of Cardiac Energetics, NHLBI, NIH Building 10, Room B1D-412, msc-1061, Bethesda, Maryland 20892-1061 (United States)
2005-01-01T23:59:59.000Z
Magnetic resonance (MR) and computed tomography coronary imaging is susceptible to artifacts caused by motion of the heart. The presence of rest periods during the cardiac and respiratory cycles suggests that images free of motion artifacts could be acquired. In this paper, we studied the rest period (RP) duration of the coronary arteries during a cardiac contraction and a tidal respiratory cycle. We also studied whether three MR motion correction methods could be used to increase the respiratory RP duration. Free breathing x-ray coronary angiograms were acquired in ten patients. The three-dimensional (3D) structure of the coronary arteries was reconstructed from a biplane acquisition using stereo reconstruction methods. The 3D motion of the arterial model was then recovered using an automatic motion tracking algorithm. The motion field was then decomposed into separate cardiac and respiratory components using a cardiac respiratory parametric model. For the proximal-to-middle segments of the right coronary artery (RCA), a cardiac RP (<1 mm 3D displacement) of 76{+-}34 ms was measured at end systole (ES), and 65{+-}42 ms in mid-diastole (MD). The cardiac RP was 80{+-}25 ms at ES and 112{+-}42 ms at MD for the proximal 5 cm of the left coronary tree. At end expiration, the respiratory RP (in percent of the respiratory period) was 26{+-}8% for the RCA and 27{+-}17% for the left coronary tree. Left coronary respiratory RP (<0.5 mm 3D displacement) increased with translation (32% of the respiratory period), rigid body (51%), and affine (79%) motion correction. The RCA respiratory RP using translational (27%) and rigid body (33%) motion correction were not statistically different from each other. Measurements of the cardiac and respiratory rest periods will improve our understanding of the temporal and spatial resolution constraints for coronary imaging.
LCLS CDR Chapter 8 - Undulator
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports(Journal Article)41clothThe Bonneville PowerTariff Pages default Sign In AboutIsrelocates I UCRLr90790 RAtomic, Molecular and Optical2 238
Stratified Steady Periodic Water Waves
Samuel Walsh
2009-02-11T23:59:59.000Z
This paper considers two-dimensional stratified water waves propagating under the force of gravity over an impermeable flat bed and with a free surface. We prove the existence of a global continuum of classical solutions that are periodic and traveling. These waves, moreover, can exhibit large density variation, speed and amplitude.
Advanced downhole periodic seismic generator
Hardee, Harry C. (Albuquerque, NM); Hills, Richard G. (Las Cruces, NM); Striker, Richard P. (Albuquerque, NM)
1991-07-16T23:59:59.000Z
An advanced downhole periodic seismic generator system for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head by support and electrical cabling and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.
Down hole periodic seismic generator
Hardee, Harry C. (Albuquerque, NM); Hills, Richard G. (Las Cruces, NM); Striker, Richard P. (Albuquerque, NM)
1989-01-01T23:59:59.000Z
A down hole periodic seismic generator system for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head by support and electrical cabling and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.
Figure 2: The mercury jet target geometry. The proton beam and mercury jet cross at z=-37.5 cm.
McDonald, Kirk
that the meson production loss is negligible (beta functions of 0.3m or greater. ENERGY DEPOSITION by the focusing of the proton beam. The energy deposition in the capture system is determined and the shielding. These muons are first produced by focusing a proton beam on to a liquid mercury target, where low-energy pions
Regular simplex and periodic billiard orbit
Bedaride, Nicolas
2011-01-01T23:59:59.000Z
We consider billiard inside regular simplex of $\\mathbb{R}^n$. We show the existence of two periodic trajectories. One of period $n+1$ which passes one time by each face and one of period $2n$ which passes $n$ times through one face and one time through each other face. In both cases we obtain exact coordinates for the periodic points.
Periods Associated to Algebraic Cycles Spencer Bloch
Bloch, Spencer
K0(X) = CHp (X)Q Spencer Bloch () Periods Associated to Algebraic Cycles March 3, 2014 Albert) CHp(X, n) := H-n(Zp(X, ·)). Spencer Bloch () Periods Associated to Algebraic Cycles March 3, 2014 ) - Zp (X) CHp(X, n) := H-n(Zp(X, ·)). Spencer Bloch () Periods Associated to Algebraic Cycles March 3
A highly specific test for periodicity
Ansmann, Gerrit
2015-01-01T23:59:59.000Z
We present a method that allows to distinguish between nearly periodic and strictly periodic time series. To this purpose, we employ a conservative criterion for periodicity, namely that the time series can be interpolated by a periodic function whose local extrema are also present in the time series. Our method is intended for the analysis of time series generated by deterministic dynamical systems, where it can help telling periodic dynamics from chaotic or transient ones. We empirically investigate our method's performance and compare it to an approach based on marker events (or Poincar\\'e sections). We demonstrate that our method is capable of detecting small deviations from periodicity and outperforms the marker-event-based approach in typical situations. Our method requires no adjustment of parameters to the individual time series, yields the period length with a precision that exceeds the sampling rate, and its run time grows asymptotically linear with the length of the time series.
Seismic isolation of two dimensional periodic foundations
Yan, Y.; Mo, Y. L., E-mail: yilungmo@central.uh.edu [University of Houston, Houston, Texas 77004 (United States); Laskar, A. [Indian Institute of Technology Bombay, Powai, Mumbai (India); Cheng, Z.; Shi, Z. [Beijing Jiaotong University, Beijing (China); Menq, F. [University of Texas, Austin, Texas 78712 (United States); Tang, Y. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2014-07-28T23:59:59.000Z
Phononic crystal is now used to control acoustic waves. When the crystal goes to a larger scale, it is called periodic structure. The band gaps of the periodic structure can be reduced to range from 0.5?Hz to 50?Hz. Therefore, the periodic structure has potential applications in seismic wave reflection. In civil engineering, the periodic structure can be served as the foundation of upper structure. This type of foundation consisting of periodic structure is called periodic foundation. When the frequency of seismic waves falls into the band gaps of the periodic foundation, the seismic wave can be blocked. Field experiments of a scaled two dimensional (2D) periodic foundation with an upper structure were conducted to verify the band gap effects. Test results showed the 2D periodic foundation can effectively reduce the response of the upper structure for excitations with frequencies within the frequency band gaps. When the experimental and the finite element analysis results are compared, they agree well with each other, indicating that 2D periodic foundation is a feasible way of reducing seismic vibrations.
Optimized Periodic Control of Chaotic Systems
Robert Mettin; Thomas Kurz
1995-05-09T23:59:59.000Z
In this work, we demonstrate the open-loop control of chaotic systems by means of optimized periodic signals. The use of such signals enables us to reduce control power significantly in comparison to simple harmonic perturbations. It is found that the stabilized periodic dynamics can be changed by small, specific alterations of the control signal. Thus, low power switching between different periodic states can be achieved without feedback. The robustness of the proposed control method against noise is discussed.
Pricing Conspicuous Consumption Products in Recession Periods ...
2012-09-26T23:59:59.000Z
cally used in chemical engineering, e.g., to avoid irreversible reactions in ... Our basic problem is based on an economic setting with a recession period followed.
Periodic Measurement of Advertising Effectiveness Using Multiple-Test-Period Geo Experiments
Cortes, Corinna
of ad effectiveness measurements across time. Additionally, the experimental units should rotate betweenPeriodic Measurement of Advertising Effectiveness Using Multiple-Test-Period Geo Experiments Jon experiments to the measurement of advertising effectiveness. One reason this method of measurement
Large Scale Periodicity in Redshift Distribution
K. Bajan; M. Biernacka; P. Flin; W. Godlowski; V. Pervushin; A. Zorin
2004-08-30T23:59:59.000Z
We review the previous studies of galaxies and quasar redshifts discretisation. We present also the investigations of the large scale periodicity, detected by pencil--beam observations, which revealed 128 (1/h) Mpc period, afterwards confirmed with supercluster studies. We present the theoretical possibility of obtaining such a periodicity using a toy-model. We solved the Kepler problem, i.e. the equation of motion of a particle with null energy moving in the uniform, expanding Universe, decribed by FLRW metrics. It is possible to obtain theoretically the separation between large scale structures similar to the observed one.
PERIODIC WAVELET TRANSFORMS AND PERIODICITY JOHN J. BENEDETTO AND GOTZ E. PFANDER
Pfander, GÃ¶tz
PERIODIC WAVELET TRANSFORMS AND PERIODICITY DETECTION JOHN J. BENEDETTO AND GÂ¨OTZ E. PFANDER Key words. Continuous wavelet transform, epileptic seizure prediction, periodicity detection algorithm, optimal generalized Haar wavelets, wavelet frames on Z. AMS subject classifications. 42C99, 42C40
University of Oregon Libraries Types of Periodicals
Lockery, Shawn
events & news Primary source for popular culture Short articles Interviews Some book reviews LargelyUniversity of Oregon Libraries Types of Periodicals Scholarly Sources Popular Sources SCHOLARLY & biographical information Statistics, including forecasts Some book reviews Commentary on political & social
Impact of Motor Failures on Payback Periods
Cheek, K. F.; Pillay, P.; Dudley, K. J.
This paper uses MotorMaster and Vaughen's Complete Price Guide to determine payback periods for different motor failure scenarios. Some scenarios considered are rewinds, reconditions, and replacement of bearings. Prices for these repairs...
Impact of Motor Failures on Payback Periods
Cheek, K. F.; Pillay, P.; Dudley, K. J.
1995-01-01T23:59:59.000Z
This paper uses MotorMaster and Vaughen's Complete Price Guide to determine payback periods for different motor failure scenarios. Some scenarios considered are rewinds, reconditions, and replacement of bearings. Prices for these repairs...
The periodicity of the eta Carinae events
A. Damineli; M. F. Corcoran; D. J. Hillier; O. Stahl; R. S. Levenhagen; N. V. Leister; J. H. Groh; M. Teodoro; J. F. Albacete Colombo; F. Gonzalez; J. Arias; H. Levato; M. Grosso; N. Morrell; R. Gamen; G. Wallerstein; V. Niemela
2007-11-27T23:59:59.000Z
Extensive spectral observations of eta Carinae over the last cycle, and particularly around the 2003.5 low excitation event, have been obtained. The variability of both narrow and broad lines, when combined with data taken from two earlier cycles, reveal a common and well defined period. We have combined the cycle lengths derived from the many lines in the optical spectrum with those from broad-band X-rays, optical and near-infrared observations, and obtained a period length of 2022.7+-1.3 d. Spectroscopic data collected during the last 60 years yield an average period of 2020+-4 d, consistent with the present day period. The period cannot have changed by more than $\\Delta$P/P=0.0007 since 1948. This confirms the previous claims of a true, stable periodicity, and gives strong support to the binary scenario. We have used the disappearance of the narrow component of HeI 6678 to define the epoch of the Cycle 11 minimum, T_0=JD 2,452,819.8. The next event is predicted to occur on 2009 January 11 (+-2 days). The dates for the start of the minimum in other spectral features and broad-bands is very close to this date, and have well determined time delays from the HeI epoch.
Kepler and the long-period variables
Hartig, Erich; Lebzelter, Thomas [University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Cash, Jennifer [Department of Biological and Physical Sciences, South Carolina State University, P.O. Box 7024, Orangeburg, SC 29117 (United States); Hinkle, Kenneth H.; Mighell, Kenneth J. [National Optical Astronomy Observatories, P.O. Box 26732, Tucson, AZ 85726 (United States); Walter, Donald K., E-mail: erich.hartig@univie.ac.at, E-mail: thomas.lebzelter@univie.ac.at, E-mail: jcash@physics.scsu.edu, E-mail: hinkle@noao.edu, E-mail: mighell@noao.edu, E-mail: dkw@physics.scsu.edu [Department of Biological and Physical Sciences, South Carolina State University, P.O. Box 7296, Orangeburg, SC 29117 (United States)
2014-12-01T23:59:59.000Z
High-precision Kepler photometry is used to explore the details of asymptotic giant branch (AGB) light curves. Since AGB variability has a typical timescale on the order of a year, we discuss at length the removal of long-term trends and quarterly changes in Kepler data. Photometry for a small sample of nine semi-regular (SR) AGB stars is examined using a 30 minute cadence over a period of 45 months. While undergoing long-period variations of many magnitudes, the light curves are shown to be smooth at the millimagnitude level over much shorter time intervals. No flares or other rapid events were detected on a sub-day timescale. The shortest AGB period detected is on the order of 100 days. All the SR variables in our sample are shown to have multiple modes. This is always the first overtone, typically combined with the fundamental. A second common characteristic of SR variables is shown to be the simultaneous excitation of multiple closely separated periods for the same overtone mode. Approximately half the sample had a much longer variation in the light curve, likely a long secondary period (LSP). The light curves were all well represented by a combination of sinusoids. However, the properties of the sinusoids are time variable, with irregular variations present at low levels. No non-radial pulsations were detected. It is argued that the LSP variation seen in many SR variables is intrinsic to the star and linked to multiple mode pulsation.
New Science with the APS Superconducting Undulator
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
of the Nature Materials News & Views article, "Quasicrystals: Model structures," by Marc de Boissieu, which can be read here; and the APS science and research highlight found...
Emergent hyperuniformity in periodically-driven emulsions
Joost H. Weijs; Raphaël Jeanneret; Rémi Dreyfus; Denis Bartolo
2015-04-28T23:59:59.000Z
We report the emergence of large-scale hyperuniformity in microfluidic emulsions. Upon periodic driving confined emulsions undergo a first-order transition from a reversible to an irreversible dynamics. We evidence that this dynamical transition is accompanied by structural changes at all scales yielding macroscopic yet finite hyperuniform structures. Numerical simulations are performed to single out the very ingredients responsible for the suppression of density fluctuations. We show that as opposed to equilibrium systems the long-range nature of the hydrodynamic interactions are not required for the formation of hyperuniform patterns, thereby suggesting a robust relation between reversibility and hyperuniformity which should hold in a broad class of periodically driven materials.
Thermo-quantum diffusion in periodic potentials
R. Tsekov
2012-01-18T23:59:59.000Z
Quantum Brownian motion in a periodic cosine potential is studied and a simple estimate of the tunneling effect is obtained in the frames of a quasi-equilibrium semiclassical approach. It is shown that the latter is applicable for heavy particles but electrons cannot be described properly since the quantum effects dominate over the thermal ones. The purely quantum electron diffusion is investigated at zero temperature and demonstrates that electrons do not obey the classical Einstein law of Brownian motion in the field of periodic potentials, since the dispersion of the wave packet increases logarithmically in time.
Sequential conditions for fixed and periodic points
Peters, Burnis Charles
1970-01-01T23:59:59.000Z
) (Member) ~A (Month) 1970 (Year) ~04SQQ ABSTRACT Sec, uential Conditions fo. Fixed and Periodic Points (August 1970) Burnis C. Peter, Jr. , B. A. , Texas ASM University; M. S. , Texas A&M University Directed by: Jack Bryant and L. F. Guseman, Jr.... Let (X, d) be a metric space and f a selfmap of X. It is shown that a number of known theorems on the existence of fixed and periodic points are related through simple properties of the n sequence (f ) of iterates . ACMOVI. EDGEMENTS I wish...
5. Wavelengths and periods of field motions
Finlay, Christopher
. Using a technique based on the Radon transform [2], we determined the amount of power propagating5. Wavelengths and periods of field motions 2D frequency-wavenumber (FK) power spectra were of the large scale magnetic field at the surface of the core. Here we deconstruct such a model (gufm1
Quantum transport calculations using periodic boundaryconditions
Wang, Lin-Wang
2004-06-15T23:59:59.000Z
An efficient new method is presented to calculate the quantum transports using periodic boundary conditions. This method allows the use of conventional ground state ab initio programs without big changes. The computational effort is only a few times of a normal groundstate calculations, thus is makes accurate quantum transport calculations for large systems possible.
Student Job Review Questionnaire / Periodic Survey
Amin, S. Massoud
Student Job Review Questionnaire / Periodic Survey FOR OHR USE ONLY No Change Date Received JRQ Number Notice Number Job Family Title Job Family Number New Pay Rate/Range Certifiable Yes No Effective Date Approved for Notice Letter Date Notice Mailed Job Review Questionnaire (JRQ) (Student Request
clock period selection method slack minimization criteria
California at Irvine, University of
An optimal clock period selection method based on slack minimization criteria EnShou Chang Daniel the effect of clock slack on the performance of designs and present an algorithm to find a slack]: allocation, scheduling and binding. The purpose of alloca tion is to determine the number of resources
Periodic Reward-Based Scheduling and Its
Aydin, Hakan
catastrophic. Examples of real-time systems can be found in control systems of nuclear power plants, air36 Periodic Reward-Based Scheduling and Its Application to Power-Aware Real-Time Systems Hakan ........................... 36-9 Modeling Real-Time Workload and Energy on a Variable Speed CPU · Correlating Real-Time Power
Elsevier Journal Specific Embargo Periods 2013 Journal Name Issn Embargo Period
Ayala-Rincón, Mauricio
Elsevier Journal Specific Embargo Periods 2013 Journal Name Issn Embargo Period ACADEMIC PEDIATRICS 18762859 12 ACADEMIC RADIOLOGY 10766332 12 ACC CARDIOSOURCE REVIEW JOURNAL 15568571 12 ACCIDENT ANALYSIS 18759637 24 AEROSPACE SCIENCE AND TECHNOLOGY 12709638 24 AESTHETIC SURGERY JOURNAL 1090820X 12 AESTHETISCHE
Chaotic Transport in Planar Periodic Vortical Flows
Taehoon Ahn; Seunghwan Kim
1993-09-24T23:59:59.000Z
We have studied a chaotic transport in a two-dimensional periodic vortical flow under a time-dependent perturbation with period T where the global diffusion occurs along the stochastic web. By using the Melnikov method we construct the separatrix map describing the approximate dynamics near the saddle separatrices. Focusing on the small T, the width of the stochastic layer is calculated analytically by using the residue criterion and the diffusion constant by using the random phase assumption and correlated random walks. The analytical results are in good agreements with the results of two different types of numerical simulations by integrations of the Hamilton's equation of motion and by iterations of the separatrix map, which establishes the validity of the use of the separatrix map.
Lengthening the Storage Period of Cucumbers.
Hawthorn, L. R. (Leslie Rushton); Whitacre, Jessie (Jessie Opal); Yarnell, S. H. (Sidney Howe)
1939-01-01T23:59:59.000Z
for profit. Mkt. Grow. Jour. 52 : 206-208. 2. Hawthorn, Leslie R., 1934. Cellophane and waxed paper wrappers for storing cucum- bers. Proc. Amer. Soc. Hort. Sci., 32 : 578-582. 2. Stahl, Arthur L. and Fifield, Willard M., 1936. Cold storage studies... STATION A. B. CONNER, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 576 AUGUST 1939 DIVISION OF RURAL HOME RESEARCH AND DIVISION OF HORTICULTURE 1NGTHENING THE STORAGE PERIOD OF CUCUMBERS AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS...
Periodic-Orbit Theory of Level Correlations
Stefan Heusler; Sebastian Müller; Alexander Altland; Petr Braun; Fritz Haake
2006-10-20T23:59:59.000Z
We present a semiclassical explanation of the so-called Bohigas-Giannoni-Schmit conjecture which asserts universality of spectral fluctuations in chaotic dynamics. We work with a generating function whose semiclassical limit is determined by quadruplets of sets of periodic orbits. The asymptotic expansions of both the non-oscillatory and the oscillatory part of the universal spectral correlator are obtained. Borel summation of the series reproduces the exact correlator of random-matrix theory.
Inference and Visualization of Periodic Sequences
Sun, Ying
2011-10-21T23:59:59.000Z
OF PHILOSOPHY Approved by: Co-Chairs of Committee, Jeffrey D. Hart Marc G. Genton Committee Members, Raymond J. Carroll Kenneth P. Bowman Head of Department, Simon J. Sheather August 2011 Major Subject: Statistics iii ABSTRACT Inference... and Visualization of Periodic Sequences. (August 2011) Ying Sun, M.S., Tsinghua University Co?Chairs of Advisory Committee: Dr. Jeffrey D. Hart Dr. Marc G. Genton This dissertation is composed of four articles describing inference and visualiza- tion...
SEXUAL SIGNALING IN PERIODICAL CICADAS, MAGICICADA SPP. (HEMIPTERA: CICADIDAE)
Simon, Chris
SEXUAL SIGNALING IN PERIODICAL CICADAS, MAGICICADA SPP. (HEMIPTERA: CICADIDAE) by JOHN R. COOLEY1 behavior of periodical cicadas (Insecta: Hemiptera: Magicicada spp.) has been considered enigmatic because
Microsoft Word - Alcoa Extended Initial Period ROD - 2010-10...
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Extended Initial Period... 6 b. Benefits to BPA will equal or exceed costs for the Extended Initial Period of the Block Contract. ......
Almost Periodic Measures and Meyer Sets
Nicolae Strungaru
2015-01-05T23:59:59.000Z
In the first part, we construct a cut and project scheme from a family $\\{P_\\varepsilon\\}$ of sets verifying four conditions. We use this construction to characterize weighted Dirac combs defined by cut and project schemes and by continuous functions on the internal groups in terms of almost periodicity. We are also able to characterise those weighted Dirac combs for which the internal function is compactly supported. Lastly, using the same cut and project construction for $\\varepsilon$-dual sets, we are able to characterise Meyer sets in $\\sigma$-compact locally compact Abelian groups.
Down-hole periodic seismic generator
Hardee, H.C.; Hills, R.G.; Striker, R.P.
1982-10-28T23:59:59.000Z
A down hole periodic seismic generator system is disclosed for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head by support and electrical cabling and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.
Electromagnetic Siegert states for periodic dielectric structures
Friends R. Ndangali; Sergei V. Shabanov
2011-08-09T23:59:59.000Z
The formalism of Siegert states to describe the resonant scattering in quantum theory is extended to the resonant scattering of electromagnetic waves on periodic dielectric arrays. The excitation of electromagnetic Siegert states by an incident wave packet and their decay is studied. The formalism is applied to develop a theory of coupled electromagnetic resonances arising in the electromagnetic scattering problem for two such arrays separated by a distance 2h (or, generally, when the physical properties of the scattering array depend on a real coupling parameter h). Analytic properties of Siegert states as functions of the coupling parameter h are established by the Regular Perturbation Theorem which is an extension the Kato-Rellich theorem to the present case. By means of this theorem, it is proved that if the scattering structure admits a bound state in the radiation continuum at a certain value of the coupling parameter h, then there always exist regions within the structure in which the near field can be amplified as much as desired by adjusting the value of h. This establishes a rather general mechanism to control and amplify optical nonlinear effects in periodically structured planar structures possessing a nonlinear dielectric susceptibility.
Dynamical system theory of periodically collapsing bubbles
Yukalov, V I; Sornette, D
2015-01-01T23:59:59.000Z
We propose a reduced form set of two coupled continuous time equations linking the price of a representative asset and the price of a bond, the later quantifying the cost of borrowing. The feedbacks between asset prices and bonds are mediated by the dependence of their "fundamental values" on past asset prices and bond themselves. The obtained nonlinear self-referencing price dynamics can induce, in a completely objective deterministic way, the appearance of periodically exploding bubbles ending in crashes. Technically, the periodically explosive bubbles arise due to the proximity of two types of bifurcations as a function of the two key control parameters $b$ and $g$, which represent, respectively, the sensitivity of the fundamental asset price on past asset and bond prices and of the fundamental bond price on past asset prices. One is a Hopf bifurcation, when a stable focus transforms into an unstable focus and a limit cycle appears. The other is a rather unusual bifurcation, when a stable node and a saddle...
Xifeng Su; Lei Zhang; Rafael de la Llave
2015-03-11T23:59:59.000Z
We consider 1-D quasi-periodic Frenkel-Kontorova models (describing, for example, deposition of materials in a quasi-periodic substratum). We study the existence of equilibria whose frequency (i.e. the inverse of the density of deposited material) is resonant with the frequencies of the substratum. We study perturbation theory for small potential. We show that there are perturbative expansions to all orders for the quasi-periodic equilibria with resonant frequencies. Under very general conditions, we show that there are at least two such perturbative expansions for equilibria for small values of the parameter. We also develop a dynamical interpretation of the equilibria in these quasi-periodic media. We show that the dynamical system has very unusual properties. Using these, we obtain results on the Lyapunov exponents of the resonant quasi-periodic solutions. In a companion paper, we develop a rather unusual KAM theory (requiring new considerations) which establishes that the perturbative expansions converge when the perturbing potentials satisfy a one-dimensional constraint.
Imtak Jeon; Neil Lambert; Paul Richmond
2012-11-29T23:59:59.000Z
We consider periodic arrays of M2-branes in the ABJM model in the spirit of a circle compactification to D2-branes in type IIA string theory. The result is a curious formulation of three-dimensional maximally supersymmetric Yang-Mills theory in terms of fermions, seven transverse scalars, a non-dynamical gauge field and an additional scalar `dual gluon'. Upon further T-duality on a transverse torus we obtain a non-manifest-Lorentz-invariant description of five-dimensional maximally supersymmetric Yang-Mills. Here the additional scalar field can be thought of as the components of a two-form along the torus. This action can be viewed as an M-theory description of M5-branes on ${\\mathbb T}^3$.
Fluorescence in nonlocal dissipative periodic structures
Francesco Intravaia; Kurt Busch
2015-02-24T23:59:59.000Z
We present an approach for the description of fluorescence from optically active material embedded in layered periodic structures. Based on an exact electromagnetic Green's tensor analysis, we determine the radiative properties of emitters such as the local photonic density of states, Lamb shifts, line widths etc. for a finite or infinite sequence of thin alternating plasmonic and dielectric layers. In the effective medium limit, these systems may exhibit hyperbolic dispersion relations so that the large wave-vector characteristics of all constituents and processes become relevant. These include the finite thickness of the layers, the nonlocal properties of the constituent metals, and local-field corrections associated with an emitter's dielectric environment. In particular, we show that the corresponding effects are non-additive and lead to considerable modifications of an emitter's luminescence properties.
Periodic relativity: basic framework of the theory
Vikram H. Zaveri
2014-11-25T23:59:59.000Z
An alternative gravity theory is proposed which does not rely on Riemannian geometry and geodesic trajectories. The theory named periodic relativity (PR) does not use the weak field approximation and allows every two body system to deviate differently from the flat Minkowski metric. PR differs from general relativity (GR) in predictions of the proper time intervals of distant objects. PR proposes a definite connection between the proper time interval of an object and gravitational frequency shift of its constituent particles as the object travels through the gravitational field. PR is based on the dynamic weak equivalence principle which equates the gravitational mass with the relativistic mass. PR provides very accurate solutions for the Pioneer anomaly and the rotation curves of galaxies outside the framework of general relativity. PR satisfies Einstein's field equations with respect to the three major GR tests within the solar system and with respect to the derivation of Friedmann equation in cosmology. This article defines the underlying framework of the theory.
Entrainment control of chaos near unstable periodic orbits
R. Mettin
1996-10-16T23:59:59.000Z
It is demonstrated that improved entrainment control of chaotic systems can maintain periodic goal dynamics near unstable periodic orbits without feedback. The method is based on the optimization of goal trajectories and leads to small open-loop control forces.
Orbital stability of periodic waves for the nonlinear Schrodinger equation
Gallay, Thierry
Orbital stability of periodic waves for the nonlinear SchrË?odinger equation Thierry Gallay Institut: Thierry Gallay, Thierry.Gallay@ujfÂgrenoble.fr Keywords: Nonlinear SchrË?odinger equation, periodic waves
Orbital stability of periodic waves for the nonlinear Schrodinger equation
Orbital stability of periodic waves for the nonlinear SchrÂ¨odinger equation Thierry Gallay Institut: Thierry Gallay, Thierry.Gallay@ujf-grenoble.fr Keywords: Nonlinear SchrÂ¨odinger equation, periodic waves
Orbital stability of periodic waves for the nonlinear Schrodinger equation
Boyer, Edmond
Orbital stability of periodic waves for the nonlinear Schr¨odinger equation Thierry Gallay Institut: Thierry Gallay, Thierry.Gallay@ujf-grenoble.fr Keywords: Nonlinear Schr¨odinger equation, periodic waves
Periodically poled silicon Nick K. Hon,a
Jalali. Bahram
as quasi-phase matching. Periodically poled silicon PePSi adds the periodic poling capability to silicon to be harnessed for devices based on second-order nonlinear effects. As an example of the utility of the PePSi is in effect, periodically poled silicon PePSi , a new technology for efficient second-order nonlinear
Jitter-Approximation Tradeoff for Periodic Scheduling Zvika Brakerski
Patt-Shamir, Boaz
Jitter-Approximation Tradeoff for Periodic Scheduling Zvika Brakerski Dept. of Electrical the average period of a job in the schedule is blown up w.r.t. its requested period, and the jitter ratio with low jitter ratio allow the mobile devices to save power by hav- ing their receivers switched off
Steady periodic waves bifurcating for fixed-depth rotational flows
consider steady periodic water waves for rotational flows with a specified fixed-depth over a flat bed. We the existence of steady periodic water waves for rotational flows with a specified fixed depth over a flat bedSteady periodic waves bifurcating for fixed-depth rotational flows David Henry School
Global Entrainment of Transcriptional Systems to Periodic Inputs
Sontag, Eduardo
Global Entrainment of Transcriptional Systems to Periodic Inputs Giovanni Russo1 , Mario di that biological networks, such as transcriptional systems, can be globally entrained to external periodic inputs) Global Entrainment of Transcriptional Systems to Periodic Inputs. PLoS Comput Biol 6(4): e1000739. doi:10
Periodic eigendecomposition and its application to Kuramoto-Sivashinsky system
Xiong Ding; Predrag Cvitanovi?
2014-06-18T23:59:59.000Z
Periodic eigendecomposition algorithm for calculating eigenvectors of a periodic product of a sequence of matrices, an extension of the periodic Schur decomposition, is formulated and compared with the recently proposed covariant vectors algorithms. In contrast to those, periodic eigendecomposition requires no power iteration and is capable of determining not only the real eigenvectors, but also the complex eigenvector pairs. Its effectiveness, and in particular its ability to resolve eigenvalues whose magnitude differs by hundreds of orders, is demonstrated by applying the algorithm to computation of the full linear stability spectrum of periodic solutions of Kuramoto-Sivashinsky system.
Convection, granulation and period jitter in classical Cepheids
Neilson, Hilding R
2014-01-01T23:59:59.000Z
Analyses of recent observations of the sole classical Cepheid in the Kepler field, V1154 Cygni, found random changes of about 30 minutes in the pulsation period. These period changes challenge standard theories of pulsation and evolution because the period change is non-secular, and explaining this period jitter is necessary for understanding stellar evolution and the role of Cepheids as precise standard candles. We suggest that convection and convective hot spots can explain the observed period jitter. Convective hot spots alter the timing of flux maximum and minimum in the Cepheid light curve, hence change the measured pulsation period. We present a model of random hot spots that generate a localized flux excess that perturbs the Cepheid light curve and consequently the pulsation period which is consistent with the observed jitter. This result demonstrates how important understanding convection is for modeling Cepheid stellar structure and evolution, how convection determines the red edge of the instability...
CEQ Extends Comment Period on Revised Draft Guidance on Consideration...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Draft Guidance on Consideration of Greenhouse Gas Emissions and the Effects of Climate Change in NEPA Reviews CEQ Extends Comment Period on Revised Draft Guidance on...
Pulse vaccination in the periodic infection rate SIR epidemic model
Zhen Jin; Mainul Haque; Quanxing Liu
2006-06-09T23:59:59.000Z
A pulse vaccination SIR model with periodic infection rate $\\beta (t)$ have been proposed and studied. The basic reproductive number $R_0$ is defined. The dynamical behaviors of the model are analyzed with the help of persistence, bifurcation and global stability. It has been shown that the infection-free periodic solution is globally stable provided $R_0 1$. Standard bifurcation theory have been used to show the existence of the positive periodic solution for the case of $R_0 \\to1^+$. Finally, the numerical simulations have been performed to show the uniqueness and the global stability of the positive periodic solution of the system.
Pressure-driven reconnection and quasi periodical oscillations in plasmas
Paccagnella, R., E-mail: roberto.paccagnella@igi.cnr.it [Consorzio RFX and Istituto Gas Ionizzati del Consiglio Nazionale delle Ricerche (CNR), Padova (Italy)
2014-03-15T23:59:59.000Z
This paper presents a model for an ohmically heated plasma in which a feedback exists between thermal conduction and transport, on one side, and the magneto-hydro-dynamical stability of the system, on the other side. In presence of a reconnection threshold for the magnetic field, a variety of periodical or quasi periodical oscillations for the physical quantities describing the system are evidenced. The model is employed to interpret the observed quasi periodical oscillations of electron temperature and perturbed magnetic field around the so called “Single Helical” state in the reversed field pinch, but its relevance for other periodical phenomena observed in magnetic confinement systems, especially in tokamaks, is suggested.
Multilevel interference lithography--fabricating sub-wavelength periodic nanostructures
Chang, Chih-Hao, 1980-
2008-01-01T23:59:59.000Z
Periodic nanostructures have many exciting applications, including high-energy spectroscopy, patterned magnetic media, photonic crystals, and templates for self-assembly. Interference lithography (IL) is an attractive ...
Green's function analysis of periodic structures in computational electromagnetics
Van Orden, Derek
2011-01-01T23:59:59.000Z
the two-dimensional periodic Green's function," IEEE Trans.evaluation of the Green's function for the Helmholtzrepresentations of certain Green's functions," J. Comp.
Saving and Using Encountered Information: Implications for Electronic Periodicals
Marshall, Cathy
Saving and Using Encountered Information: Implications for Electronic Periodicals Catherine C of a focus on electronic publications, we undertook an exploratory study of how people saved and used study participants had examples of materials they had deliberately saved from periodicals, ranging from
Multivariate periodic wavelet analysis Dirk Langemann, Jurgen Prestin
Prestin, JÃ¼rgen
Multivariate periodic wavelet analysis Dirk Langemann, JÂ¨urgen Prestin University of LÂ¨ubeck, Institute of Mathematics, Wallstr. 40, D-23560 LÂ¨ubeck, Germany Abstract General multivariate periodic are generalized to multivariate shift invariant spaces on non-tensor-product pat- terns. In particular
Dual periodicities in the rotational modulation of Saturn narrowband emissions
Gurnett, Donald A.
Dual periodicities in the rotational modulation of Saturn narrowband emissions S.Y. Ye,1 D. A emissions is examined, restricting the spacecraft location to either the northern or the southern hemisphere of Saturn. It is found that in both hemispheres, the modulation period of 5 kHz narrowband emissions has two
Analysis of Periodic GrowthDisturbance Models Timothy C. Reluga
Reluga, Tim
model for a fluctuating population. Changes in the disturbance frequency are shown to generate a period-bubbling bifurcation structure and population dynamics that are most variable at intermediate disturbance frequenciesAnalysis of Periodic GrowthDisturbance Models Timothy C. Reluga treluga
Efficient Mining of Partial Periodic Patterns in Time Series Database
Dong, Guozhu
Efficient Mining of Partial Periodic Patterns in Time Series Database In ICDE 99 Jiawei Han \\Lambda peri odic patterns in timeseries databases, is an interesting data mining problem. Previous studies several algorithms for efficient mining of par tial periodic patterns, by exploring some interesting
Periodic Solutions of a Nonlinear Evolution Problem from Heterogeneous Catalysis
Bothe, Dieter
Periodic Solutions of a Nonlinear Evolution Problem from Heterogeneous Catalysis Dieter Bothe for heterogeneous catalysis in a stirred multi-phase chemical reactor. Since the appearance of T-periodic feeds for this evolution problem are provided and applied to the class of reaction-diffusion systems mentioned above. AMS
Quantum coherent switch utilizing commensurate nanoelectrode and charge density periodicities
Harrison, Neil (Santa Fe, NM); Singleton, John (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)
2008-08-05T23:59:59.000Z
A quantum coherent switch having a substrate formed from a density wave (DW) material capable of having a periodic electron density modulation or spin density modulation, a dielectric layer formed onto a surface of the substrate that is orthogonal to an intrinsic wave vector of the DW material; and structure for applying an external spatially periodic electrostatic potential over the dielectric layer.
Unstable periodic orbits in a chaotic meandering jet flow
Uleysky, M Yu; Prants, S V; 10.1088/1751-8113/41/21/215102
2012-01-01T23:59:59.000Z
We study the origin and bifurcations of typical classes of unstable periodic orbits in a jet flow that was introduced before as a kinematic model of chaotic advection, transport and mixing of passive scalars in meandering oceanic and atmospheric currents. A method to detect and locate the unstable periodic orbits and classify them by the origin and bifurcations is developed. We consider in detail period-1 and period-4 orbits playing an important role in chaotic advection. We introduce five classes of period-4 orbits: western and eastern ballistic ones, whose origin is associated with ballistic resonances of the fourth order, rotational ones, associated with rotational resonances of the second and fourth orders, and rotational-ballistic ones associated with a rotational-ballistic resonance. It is a new kind of nonlinear resonances that may occur in chaotic flow with jets and/or circulation cells. Varying the perturbation amplitude, we track out the origin and bifurcations of the orbits for each class.
Unstable periodic orbits in a chaotic meandering jet flow
M. Yu. Uleysky; M. V. Budyansky; S. V. Prants
2007-12-25T23:59:59.000Z
We study the origin and bifurcations of typical classes of unstable periodic orbits in a jet flow that was introduced before as a kinematic model of chaotic advection, transport and mixing of passive scalars in meandering oceanic and atmospheric currents. A method to detect and locate the unstable periodic orbits and classify them by the origin and bifurcations is developed. We consider in detail period-1 and period-4 orbits playing an important role in chaotic advection. We introduce five classes of period-4 orbits: western and eastern ballistic ones, whose origin is associated with ballistic resonances of the fourth order, rotational ones, associated with rotational resonances of the second and fourth orders, and rotational-ballistic ones associated with a rotational-ballistic resonance. It is a new kind of nonlinear resonances that may occur in chaotic flow with jets and/or circulation cells. Varying the perturbation amplitude, we track out the origin and bifurcations of the orbits for each class.
Enhanced entrainability of genetic oscillators by period mismatch
Yoshihiko Hasegawa; Masanori Arita
2013-01-12T23:59:59.000Z
Biological oscillators coordinate individual cellular components so that they function coherently and collectively. They are typically composed of multiple feedback loops, and period mismatch is unavoidable in biological implementations. We investigated the advantageous effect of this period mismatch in terms of a synchronization response to external stimuli. Specifically, we considered two fundamental models of genetic circuits: smooth- and relaxation oscillators. Using phase reduction and Floquet multipliers, we numerically analyzed their entrainability under different coupling strengths and period ratios. We found that a period mismatch induces better entrainment in both types of oscillator; the enhancement occurs in the vicinity of the bifurcation on their limit cycles. In the smooth oscillator, the optimal period ratio for the enhancement coincides with the experimentally observed ratio, which suggests biological exploitation of the period mismatch. Although the origin of multiple feedback loops is often explained as a passive mechanism to ensure robustness against perturbation, we study the active benefits of the period mismatch, which include increasing the efficiency of the genetic oscillators. Our findings show a qualitatively different perspective for both the inherent advantages of multiple loops and their essentiality.
Planar resonant periodic orbits in Kuiper belt dynamics
George Voyatzis; Thomas Kotoulas
2005-02-28T23:59:59.000Z
In the framework of the planar restricted three body problem we study a considerable number of resonances associated to the Kuiper Belt dynamics and located between 30 and 48 a.u. Our study is based on the computation of resonant periodic orbits and their stability. Stable periodic orbits are surrounded by regular librations in phase space and in such domains the capture of trans-Neptunian object is possible. All the periodic orbits found are symmetric and there is evidence for the existence of asymmetric ones only in few cases. In the present work first, second and third order resonances are under consideration. In the planar circular case we found that most of the periodic orbits are stable. The families of periodic orbits are temporarily interrupted by collisions but they continue up to relatively large values of the Jacobi constant and highly eccentric regular motion exists for all cases. In the elliptic problem and for a particular eccentricity value of the primary bodies the periodic orbits are isolated. The corresponding families, where they belong to, bifurcate from specific periodic orbits of the circular problem and seem to continue up to the rectilinear problem. Both stable and unstable orbits are obtained for each case. In the elliptic problem the unstable orbits found are associated with narrow chaotic domains in phase space. The evolution of the orbits, which are located in such chaotic domains, seems to be practically regular and bounded for long time intervals.
Development of Seismic Isolation Systems Using Periodic Materials
Yan, Yiqun [Univ. of Houston, Houston, TX (United States); Mo, Yi-Lung [Univ. of Houston, Houston, TX (United States); Menq, Farn-Yuh [Univ. of Texas, Austin, TX (United States); Stokoe, II, Kenneth H. [Univ. of Texas, Austin, TX (United States); Perkins, Judy [Prairie View A & M University, Prairie View, TX (United States); Tang, Yu [Argonne National Lab. (ANL), Argonne, IL (United States)
2014-12-10T23:59:59.000Z
Advanced fast nuclear power plants and small modular fast reactors are composed of thin-walled structures such as pipes; as a result, they do not have sufficient inherent strength to resist seismic loads. Seismic isolation, therefore, is an effective solution for mitigating earthquake hazards for these types of structures. Base isolation, on which numerous studies have been conducted, is a well-defined structure protection system against earthquakes. In conventional isolators, such as high-damping rubber bearings, lead-rubber bearings, and friction pendulum bearings, large relative displacements occur between upper structures and foundations. Only isolation in a horizontal direction is provided; these features are not desirable for the piping systems. The concept of periodic materials, based on the theory of solid-state physics, can be applied to earthquake engineering. The periodic material is a material that possesses distinct characteristics that prevent waves with certain frequencies from being transmitted through it; therefore, this material can be used in structural foundations to block unwanted seismic waves with certain frequencies. The frequency band of periodic material that can filter out waves is called the band gap, and the structural foundation made of periodic material is referred to as the periodic foundation. The design of a nuclear power plant, therefore, can be unified around the desirable feature of a periodic foundation, while the continuous maintenance of the structure is not needed. In this research project, three different types of periodic foundations were studied: one-dimensional, two-dimensional, and three-dimensional. The basic theories of periodic foundations are introduced first to find the band gaps; then the finite element methods are used, to perform parametric analysis, and obtain attenuation zones; finally, experimental programs are conducted, and the test data are analyzed to verify the theory. This procedure shows that the periodic foundation is a promising and effective way to mitigate structural damage caused by earthquake excitation.
Fourier Analysis and Autocorrelation Function Applied to Periodical Nanostructures
Rockett, Angus
Fourier Analysis and Autocorrelation Function Applied to Periodical Nanostructures E. Cruz Microscopy (AFM) Image Fast Fourier Transformation Autocorrelation Function(AC) Angular Distribution] Fourier Analysis: analytical and geometrical aspects, Bray William O ed. New York: Marcel Dekker, 1994
Generalized Cost Function Based Forecasting for Periodically Measured Nonstationary Traffic
Zeng, Yong - Department of Mathematics and Statistics, University of Missouri
1 Generalized Cost Function Based Forecasting for Periodically Measured Nonstationary Traffic true value. However, such a forecast- ing function is not directly applicable for applications potentially result in insufficient allocation of bandwidth leading to short term data loss. To facilitate
Neutron-Scattering Evidence for a Periodically Modulated Superconducti...
Office of Scientific and Technical Information (OSTI)
Neutron-Scattering Evidence for a Periodically Modulated Superconducting Phase in the Underdoped Cuprate La1.905Ba0.095CuO4 Citation Details In-Document Search Title:...
Period tripling accumulation point for complexified Henon map
O. B. Isaeva; S. P. Kuznetsov
2005-09-06T23:59:59.000Z
Accumulation point of period-tripling bifurcations for complexified Henon map is found. Universal scaling properties of parameter space and Fourier spectrum intrinsic to this critical point is demonstrated.
Quality of monitoring of stochastic events by periodic and ...
David K. Y. Yau, Nung Kwan Yip, Chris Y. T. Ma, Nageswara S. V. Rao, Mallikarjun Shankar
2010-08-28T23:59:59.000Z
sensor monitoring a PoI may be periodically turned off to conserve energy, thereby extending the lifetime of the ... against physical hazards, such as chemical, biological, nuclear, radiational, and explosive (CBNRE) ...... environment. Tech. rep.
Competitive Multi-period Pricing with Fixed Inventories
Perakis, Georgia
This paper studies the problem of multi-period pricing for perishable products in a competitive (oligopolistic) market. We study non cooperative Nash equilibrium policies for sellers. At the beginning of the time horizon, ...
Experimental continuation of periodic orbits through a fold
J. Sieber; A. Gonzalez-Buelga; S. A. Neild; D. J. Wagg; B. Krauskopf
2008-06-12T23:59:59.000Z
We present a continuation method that enables one to track or continue branches of periodic orbits directly in an experiment when a parameter is changed. A control-based setup in combination with Newton iterations ensures that the periodic orbit can be continued even when it is unstable. This is demonstrated with the continuation of initially stable rotations of a vertically forced pendulum experiment through a fold bifurcation to find the unstable part of the branch.
Time-Periodic Solutions of the Einstein's Field Equations II
De-Xing Kong; Kefeng Liu; Ming Shen
2008-07-31T23:59:59.000Z
In this paper, we construct several kinds of new time-periodic solutions of the vacuum Einstein's field equations whose Riemann curvature tensors vanish, keep finite or take the infinity at some points in these space-times, respectively. The singularities of these new time-periodic solutions are investigated and some new physical phenomena are found. The applications of these solutions in modern cosmology and general relativity can be expected.
Flux avalanches in superconducting films with periodic arrays of holes.
Vlasko-Vlasov, V.; Welp, U.; Metlushko, V.; Crabtree, G. W.; Materials Science Division; Inst. of Solid State Physics RAS
2000-01-01T23:59:59.000Z
The magnetic flux dynamics in Nb films with periodic hole arrays is studied magneto-optically. Flux motion in the shape of microavalanches along {l_brace}100{r_brace} and {l_brace}110{r_brace} directions of the hole lattice is observed. At lower temperatures anisotropic large scale thermo-magnetic avalanches dominate flux entry and exit. At T-T{sub c} critical-state-like field patterns periodically appear at fractions of the matching field.
An Autonomous Adaptive Scheduling Agent for Period Searching
Eric S. Saunders; Tim Naylor; Alasdair Allan
2008-01-24T23:59:59.000Z
We describe the design and implementation of an autonomous adaptive software agent that addresses the practical problem of observing undersampled, periodic, time-varying phenomena using a network of HTN-compliant robotic telescopes. The algorithm governing the behaviour of the agent uses an optimal geometric sampling technique to cover the period range of interest, but additionally implements proactive behaviour that maximises the optimality of the dataset in the face of an uncertain and changing operating environment.
Long period fiber gratings induced by mechanical resonance
Shahal, Shir; Duadi, Hamootal; Fridman, Moti
2015-01-01T23:59:59.000Z
We present a simple, and robust method for writing long period fiber gratings with low polarization dependent losses. Our method is based on utilizing mechanical vibrations of the tapered fiber while pooling it. Our method enables real-time tunability of the periodicity, efficiency and length of the grating. We also demonstrate complex grating by writing multiple gratings simultaneously. Finally, we utilized the formation of the gratings in different fiber diameters to investigate the Young's modulus of the fiber.
Transport and Fractionation in Periodic Potential-Energy Landscapes
Kosta Ladavac; Matthew Pelton; David G. Grier
2004-04-09T23:59:59.000Z
Objects driven through periodically modulated potential-energy landscapes in two dimensions can become locked in to symmetry-selected directions that are independent of the driving force's orientation. We investigate this problem in the overdamped limit, and demonstrate that the crossover from free-flowing to locked-in transport can depend exponentially on an object's size, with this exceptional selectivity emerging from the periodicity of the environment.
Mean ZZ Ceti pulsation period gauges stellar temperature
Anjum S. Mukadam; M. H. Montgomery; A. Kim; D. E. Winget; S. O. Kepler; J. C. Clemens
2006-12-15T23:59:59.000Z
The mean pulsation period of ZZ Ceti stars increases with decreasing effective temperature as we traverse from the blue to the red edge of the instability strip. This well-established correlation between the mean period and spectroscopic temperature suggests that the mean period could be utilized as a tool to measure the relative temperature of the star independent of spectroscopy. Measuring the pulsation periods of a ZZ Ceti star is a simple, model-independent, and straight forward process as opposed to a spectroscopic determination of its temperature. Internal uncertainties in determining the spectroscopic temperature of a ZZ Ceti star are at least 200K, 15% of the 1350K width of the instability strip. The uncertainties in determining the mean period arise mostly from amplitude modulation in the pulsation spectrum and are smaller than 100s for 91% of the ZZ Ceti stars, temperature indicator rather than conventional spectroscopy. Presently we only claim that the relative temperatures of ZZ Ceti stars derived by using the mean pulsation period are certainly as good as and perhaps about 15% better than spectroscopy.
Periodic trajectories for a two-dimensional nonintegrable Hamiltonian
Baranger, M.; Davies, K.T.R.
1987-08-01T23:59:59.000Z
A numerical study is made of the classical periodic trajectories for the two-dimensional nonintegrable Hamiltonian H = 1/2(p/sup 2//sub x/+p/sup 2//sub y/)+(y-1/2x/sup 2/)/sup 2/+0.05 x/sup 2/. In addition to x--y pictures of the trajectories, E--tau (energy--period) plots of the periodic families are presented. Efforts have been ade to include all trajectories with short periods and all simple branchings of these trajectories. The monodromy matrix has been calculated in all cases, and from it the stability properties are derived. The topology of the E--tau plot has been explored, with the following results. One family may have several stable regions. The plot is not completely connected; there are islands. The plot is not a tree; there are cycles. There are isochronous branchings, period-doublings, and period-multiplyings of higher orders, and examples of each of these are presented. There is often more than one branch issuing from a branch point. Some general empirical rules are inferred. In particular, the existence of isochronous branching is seen to be a consequence of the symmetry of the Hamiltonian. All these results agree with the general classification of possible branchings derived in Ref. (10). (M. A. M. de Aguiar, C. P. Malta, M. Baranger, and K. T. R. Davies, in preparation). Finally, some nonperiodic trajectories are calculated to illustrate the fact that stable periodic trajectories lie in ''regular'' regions of phase space, while unstable ones lie in ''chaotic'' regions.
1D periodic potentials with gaps vanishing at k=0
O. Zagordi; A. Michelangeli
2008-10-13T23:59:59.000Z
Appearance of energy bands and gaps in the dispersion relations of a periodic potential is a standard feature of Quantum Mechanics. We investigate the class of one-dimensional periodic potentials for which all gaps vanish at the center of the Brillouin zone. We characterize them through a necessary and sufficient condition. Potentials of the form we focus on arise in different fields of Physics, from supersymmetric Quantum Mechanics, to Korteweg-de Vries equation theory and classical diffusion problems. The O.D.E. counterpart to this problem is the characterisation of periodic potentials for which coexistence occur of linearly independent solutions of the corresponding Schroedinger equation (Hill's equation). This result is placed in perspective of the previous related results available in the literature.
Double-periodic blue variables in the Magellanic Clouds
R. E. Mennickent; G. Pietrzynski; M. Diaz; W. Gieren
2002-12-09T23:59:59.000Z
We report the discovery, based on an inspection of the OGLE-II database, of a group of blue variables in the Magellanic Clouds showing simultaneously two kinds of photometric variability: a short-term cyclic variability with typical amplitude $\\Delta I \\sim$ 0.05 mag and period $P_{1}$ between 4 and 16 days and a sinusoidal, long-term cyclic oscillation with much larger amplitude $\\Delta I \\sim$ 0.2 mag with period $P_{2}$ in the range of 150-1000 days. We find that both periods seems to be coupled through the relationship $P_{2}$ = 35.2 $\\pm$ 0.8 $P_{1}$. In general, the short term variability is reminiscent of those shown by Algol-type binaries. We propose that the long-term oscillation could arise in the precession of a elliptical disc fed by a Roche-lobe filling companion in a low mass ratio Algol system.
Lyapunov functions for periodic matrix-valued Jacobi operators
Evgeny Korotyaev; Anton Kutsenko
2007-01-16T23:59:59.000Z
We consider periodic matrix-valued Jacobi operators. The spectrum of this operator is absolutely continuous and consists of intervals separated by gaps. We define the Lyapunov function, which is analytic on an associated Riemann surface. On each sheet the Lyapunov function has the standard properties of the Lyapunov function for the scalar case. We show that this function has (real or complex) branch points, which we call resonances. We prove that there exist two types of gaps: i) stable gaps, i.e., the endpoints are periodic and anti-periodic eigenvalues, ii) unstable (resonance) gaps, i.e., the endpoints are resonances (real branch points). We show that some spectral data determine the spectrum (counting multiplicity) of the Jacobi operator.
Periodic Discrete Energy for Long-Range Potentials
D. P. Hardin; E. B. Saff; Brian Simanek
2014-12-11T23:59:59.000Z
We consider periodic energy problems in Euclidean space with a special emphasis on long-range potentials that cannot be defined through the usual infinite sum. One of our main results builds on more recent developments of Ewald summation to define the periodic energy corresponding to a large class of long-range potentials. Two particularly interesting examples are the logarithmic potential and the Riesz potential when the Riesz parameter is smaller than the dimension of the space. For these examples, we use analytic continuation methods to provide concise formulas for the periodic kernel in terms of the Epstein Hurwitz Zeta function. We apply our energy definition to deduce several properties of the minimal energy including the asymptotic order of growth and the distribution of points in energy minimizing configurations as the number of points becomes large. We conclude with some detailed calculations in the case of one dimension, which shows the utility of this approach.
Periodic homogenization and material symmetry in linear elasticity
Mariya Ptashnyk; Brian Seguin
2015-05-07T23:59:59.000Z
Here homogenization theory is used to establish a connection between the symmetries of a periodic elastic structure associated with the microscopic properties of an elastic material and the material symmetries of the effective, macroscopic elasticity tensor. Previous results of this type exist but here more general symmetries on the microscale are considered. Using an explicit example, we show that it is possible for a material to be fully anisotropic on the microscale and yet have a nontrivial material symmetry group on the macroscale. Another example demonstrates that not all material symmetries of the macroscopic elastic tensor are generated by symmetries of the periodic elastic structure.
Period Change of Eclipsing Binaries from the ASAS Catalog
Radoslaw Poleski; Bogumil Pilecki
2006-07-10T23:59:59.000Z
We present a preliminary statistical analysis of a period change of eclipsing binaries from the ASAS Catalog of Variable Stars. For each contact and semidetached system brighter than 13.3$mag$ (in V) with a period shorter than 0.4 days and at least 300 observation points we have found an angular velocity $\\omega$ and its time derivative $\\frac{d\\omega}{dt}$. According to our accuracy there is no evidence that average $\\frac{d\\omega}{dt}$ differs from 0. Light curves for selected stars are presented.
Period doubling, information entropy, and estimates for Feigenbaum's constants
Reginald D. Smith
2013-08-03T23:59:59.000Z
The relationship between period doubling bifurcations and Feigenbaum's constants has been studied for nearly 40 years and this relationship has helped uncover many fundamental aspects of universal scaling across multiple nonlinear dynamical systems. This paper will combine information entropy with symbolic dynamics to demonstrate how period doubling can be defined using these tools alone. In addition, the technique allows us to uncover some unexpected, simple estimates for Feigenbaum's constants which relate them to log 2 and the golden ratio, phi, as well as to each other.
A wavelet-based tool for studying non-periodicity
R. Benítez; V. J. Bolós; M. E. Ramírez
2010-07-20T23:59:59.000Z
This paper presents a new numerical approach to the study of non-periodicity in signals, which can complement the maximal Lyapunov exponent method for determining chaos transitions of a given dynamical system. The proposed technique is based on the continuous wavelet transform and the wavelet multiresolution analysis. A new parameter, the \\textit{scale index}, is introduced and interpreted as a measure of the degree of the signal's non-periodicity. This methodology is successfully applied to three classical dynamical systems: the Bonhoeffer-van der Pol oscillator, the logistic map, and the Henon map.
Diffraction Properties of Periodic Lattices under Free Electron Laser Radiation
Rajkovic, I.; Busse, G.; Hallmann, J.; More, R.; Petri, M.; Quevedo, W. [Max Planck Institute for Biophysical Chemistry, 37070 Goettingen (Germany); Krasniqi, F.; Rudenko, A. [Max-Planck Advanced Study Group at CFEL, Notkestrasse 85, 22607 Hamburg (Germany); Tschentscher, T. [European XFEL GmbH, Albert-Einstein-Ring 19, 22671 Hamburg (Germany); Stojanovic, N.; Duesterer, S.; Treusch, R. [HASYLAB at DESY, Notkestrasse 85, 22607 Hamburg (Germany); Tolkiehn, M. [Institut fuer Roentgenphysik, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Techert, S. [Max Planck Institute for Biophysical Chemistry, 37070 Goettingen (Germany); Max-Planck Advanced Study Group at CFEL, Notkestrasse 85, 22607 Hamburg (Germany)
2010-03-26T23:59:59.000Z
In this Letter, we report the pioneering use of free electron laser radiation for the investigation of periodic crystalline structures. The diffraction properties of silver behenate single nanocrystals (5.8 nm periodicity) with the dimensions of 20 nmx20 nmx20 {mu}m and as powder with grain sizes smaller than 200 nm were investigated with 8 nm free electron laser radiation in single-shot modus with 30 fs long free electron laser pulses. This work emphasizes the possibility of using soft x-ray free electron laser radiation for these crystallographic studies on a nanometer scale.
Periodic Photometric Variability in the Becklin-Neugebauer Object
Lynne A. Hillenbrand; John M. Carpenter; M. F. Skrutskie
2000-10-24T23:59:59.000Z
The Becklin-Neugebauer (BN) object in the Orion Nebula Cluster (ONC) is a well-studied optically invisible, infrared-bright young stellar object, thought to be an intermediate-mass protostar. We report here that BN exhibited nearly-sinusoidal periodic variability at the near-infrared H- and Ks-bands during a one month observing campaign in 2000 March/April. The period was 8.28 days and the peak-to-peak amplitude ~0.2 mag. Plausible mechanisms for producing the observed variability characteristics are explored.
Strategic Sourcing Dashboard Reporting Period: January 2010 through December 2011
Minnesota, University of
We have accomplished $10.8 million in annual savings through our Strategic Sourcing efforts over below. Strategic Sourcing continues to have a significant emphasis for Purchasing Services, but savings/Activities/Risks for this Reporting Period Annual savings of over $200,000 was booked in the last quarter in the office and lab supply
Collective periodicity in mean-field models of cooperative behavior
Francesca Collet; Paolo Dai Pra; Marco Formentin
2015-02-06T23:59:59.000Z
We propose a way to break symmetry in stochastic dynamics by introducing a dissipation term. We show in a specific mean-field model, that if the reversible model undergoes a phase transition of ferromagnetic type, then its dissipative counterpart exhibits periodic orbits in the thermodynamic limit.
Periodic bedrock ridges on Mars David R. Montgomery,1
Montgomery, David R.
Periodic bedrock ridges on Mars David R. Montgomery,1 Joshua L. Bandfield,1 and Scott K. Becker1 to be widespread [Carr, 1981; Greeley et al., 1992; Malin and Edgett, 2001]. Although wind-streamlined yardangs interpreted as sedimentary forms [McCauley et al., 1972; Cutts and Smith, 1973; Carr, 1981; Greeley et al
lthough Earth has undergone many periods of significant environmen-
Horton, Tom
A lthough Earth has undergone many periods of significant environmen- tal change, the planet push the Earth system outside the stable environmental state of the Holocene, with consequences occurred naturally and Earth's regu- latory capacity maintained the conditions that enabled human
Greedy Approaches to Static Stochastic Robust Resource Allocation for Periodic
Maciejewski, Anthony A.
Greedy Approaches to Static Stochastic Robust Resource Allocation for Periodic Sensor Driven@us.ibm.com Abstract-- This research investigates the problem of robust resource allocation for a large class. Such systems are expected to function in an environment replete with uncertainty where the workload is likely
Temperature-induced marine export production during glacial period
Chikamoto, Megumi O.
Temperature-induced marine export production during glacial period M. O. Chikamoto,1,2 A. Abe October 2012; published 8 November 2012. [1] Proxy records indicate that export production was enhanced at the onset of the last glaciation. We examine how glacial cooling affects marine export production through
Urban Water Demand with Periodic Error Correction David R. Bell
Griffin, Ronald
them. Econometric estimates of residential demand for water abound (Dalhuisen et al. 2003Urban Water Demand with Periodic Error Correction by David R. Bell and Ronald C. Griffin February, Department of Agricultural Economics, Texas A&M University. #12;Abstract Monthly demand for publicly supplied
RIEMANN SURFACES, PLANE ALGEBRAIC CURVES AND THEIR PERIOD MATRICES
numerically the canonical map. Therefore symmetric 1991 Mathematics Subject Classification. 14Q05, 14H55, 14P for computing a representation of a compact Riemann surface as an algebraic plane curve and to compute a numerical approximation for its period matrix. We will describe a program Cars ([3]) that can be used
Spectroscopy and orbital periods of four cataclysmic variable stars
J. R. Thorstensen; C. J. Taylor
2001-05-29T23:59:59.000Z
We present spectroscopy and orbital periods Porb of four relatively little-studied cataclysmic variable stars. The stars and their periods are: AF Cam, Porb = 0.324(1) d (the daily cycle count is slightly ambiguous); V2069 Cyg (= RX J2123.7+4217), 0.311683(2) d; PG 0935+075, 0.1868(3) d; and KUV 03580+0614, 0.1495(6) d. V2069 Cyg and KUV 03580+0614 both show HeII lambda 4686 emission comparable in strength to H beta. V2069 Cyg appears to be a luminous novalike variable, and the strong HeII suggests it may be an intermediate polar. The period of KUV 03580+0614 is similar to members of the SW Sex-type novalike variables, and it shows the phase-dependent absorption in the Balmer and He I lines typical of this subclass. AF Cam shows absorption features from a K-type secondary, as expected given its rather long orbital period. The secondary spectrum and the outburst magnitude both suggest that AF Cam is about 1 kpc distant. The spectrum of PG 0935+075 resembles that of a dwarf nova at minimum light, with a noticeable contribution from an M-dwarf secondary star. The secondary spectrum and a tentative outburst magnitude both suggest a distance near 500 pc.
Marchenko-Ostrovski mappings for periodic Jacobi matrices
Evgeny Korotyaev; Anton Kutsenko
2007-10-15T23:59:59.000Z
We consider the 1D periodic Jacobi matrices. The spectrum of this operator is purely absolutely continuous and consists of intervals separated by gaps. We solve the inverse problem (including characterization) in terms of vertical slits on the quasimomentum domain . Furthermore, we obtain a priori two-sided estimates for vertical slits in terms of Jacoby matrices.
Bounded, Periodic Relative Motion using Canonical Epicyclic Orbital Elements
Rowley, Clarence W.
Bounded, Periodic Relative Motion using Canonical Epicyclic Orbital Elements N. Jeremy Kasdin using canonical perturbation theory for studying relative motion trajectories and for finding simple motion [2, 3, 4, 5]. This has the advantage that Lagrange's planetary equations (LPEs) or Gauss
The theme of a vanishing period. Daniel Barlet
Paris-Sud XI, Université de
period, Bernstein polynomial, filtered Gauss-Manin sys- tem, (a,b)-module, Brieskorn module. Contents 1.1 Stability by quotient and twisted duality. . . . . . . . . . . . . . . . . 10 3.2 Standard and canonical forms for a []-primitive theme. . . . . . . . 18 4 The uniqueness of a canonical form 23 4
CLATHRATE HYDRATES FORMATION IN SHORT-PERIOD COMETS
Marboeuf, Ulysse; Mousis, Olivier; Petit, Jean-Marc [Institut UTINAM, CNRS-UMR 6213, Observatoire de Besancon, BP 1615, 25010 Besancon Cedex (France); Schmitt, Bernard, E-mail: marboeuf@ujf-grenoble.f [Universite Joseph Fourier, Laboratoire de Planetologie de Grenoble, CNRS INSU (France)
2010-01-01T23:59:59.000Z
The initial composition of current models of cometary nuclei is only based on two forms of ice: crystalline ice for long-period comets and amorphous ice for short-period comets. A third form of ice, i.e., clathrate hydrate, could exist within the short-period cometary nuclei, but the area of formation of this crystalline structure in these objects has never been studied. Here, we show that the thermodynamic conditions in the interior of short-period comets allow the existence of clathrate hydrates in Halley-type comets. We show that their existence is viable in the Jupiter family comets only when the equilibrium pressure of CO clathrate hydrate is at least 1 order of magnitude lower than the usually assumed theoretical value. We calculate that the amount of volatiles that could be trapped in the clathrate hydrate layer may be orders of magnitude greater than the daily amount of gas released at the surface of the nucleus at perihelion. The formation and the destruction of the clathrate hydrate cages could then explain the diversity of composition of volatiles observed in comets, as well as some pre-perihelion outbursts. We finally show that the potential clathrate hydrate layer in comet 67P/Churyumov-Gerasimenko would, unfortunately, be deep inside the nucleus, out of reach of the Rosetta lander. However, such a clathrate hydrate layer would show up by the gas composition of the coma.
Extraordinary infrared transmission through a periodic bowtie aperture array
Xu, Xianfan
Extraordinary infrared transmission through a periodic bowtie aperture array Edward C. Kinzel to surface plasmon polariton (SPP) resonances and/or RayleighWood anomalies (RWA). Bowtie apertures to be strongly resonant. We demonstrate here that the total transmission through a bowtie aperture array can
Some Reflections on the Periodization of Tibetan History
Cuevas, Bryan
2006-01-01T23:59:59.000Z
Some Reflections on the Periodization of Tibetan History* Bryan J. Cuevas(Florida State University, USA) istory is always expressed as a narrative, a story about the past. Towrite a story out of the events of the past, historians must give...
Bifurcation and Stability Properties of Periodic Solutions to Two Nonlinear
Fiedler, Bernold
motions of suspension bridges. Though they were able to replicate the phenomena observed on the Tacoma in suspen- sion bridges. We contrast the multiplicity, bifurcation, and stability of periodic solutions-doubling and quadrupling) differs significantly. Keywords: suspension bridge, continuation, bifurcation, stability
Local Lyapunov Functions for periodic and finite-time ODEs
Hafstein, Sigurður Freyr
Local Lyapunov Functions for periodic and finite-time ODEs Peter Giesl and Sigurdur Hafstein Abstract Lyapunov functions for general systems are difficult to construct. How- ever, for autonomous Lyapunov function by solving a matrix equa- tion. Consequently, the same function is a local Lyapunov
NANO EXPRESS Fabrication of Large Area Periodic Nanostructures Using
Mohseni, Hooman
, such as photonic band-gap materials, high dense data storage, and photonic devices. We have developed a maskless areas, such as photonic band-gap materials [1], high dense data storage [2], and photonic devices [3NANO EXPRESS Fabrication of Large Area Periodic Nanostructures Using Nanosphere Photolithography
Proton aurora related to intervals of pulsations of diminishing periods
California at Berkeley, University of
Proton aurora related to intervals of pulsations of diminishing periods A. G. Yahnin,1 T. A are generated because of a cyclotron instability of the anisotropic distribution of ring current ions. Proton precipitation produced by the cyclotron instability can be responsible for proton aurora. Indeed
Periodic schedules for Unitary Timed Weighted Event Graphs
Paris-Sud XI, Université de
Event Graph model (TEG also called marked graphs [5]) and dataflow graphs, oftenly used in the computer questions are polynomially solved for ordinary TEG [1], [5], [6], [8]. In particular, it has been shown that if a TEG is live, there always exists a periodic schedule with the optimal throughput (i.e. with the same
Model Reduction Near Periodic Orbits of Hybrid Dynamical Systems
Sastry, S. Shankar
manipulation in manufacturing [2], gene regulation in cells [3], and power generation in electrical systems [41 Model Reduction Near Periodic Orbits of Hybrid Dynamical Systems Samuel A. Burden, Shai Revzen system. We demonstrate reduction of a highÂdimensional underactuated mechanical model for terrestrial
Periodic fluctuations in deep water formation due to sea ice
Raj Saha
2015-02-21T23:59:59.000Z
During the last ice age several quasi-periodic abrupt warming events took place. Known as Dansgaard-Oeschger (DO) events their effects were felt globally, although the North Atlantic experienced the largest temperature anomalies. Paleoclimate data shows that the fluctuations often occurred right after massive glacial meltwater releases in the North Atlantic and in bursts of three or four with progressively decreasing strengths. In this study a simple dynamical model of an overturning circulation and sea ice is developed with the goal of understanding the fundamental mechanisms that could have caused the DO events. Interaction between sea ice and the overturning circulation in the model produces self-sustained oscillations. Analysis and numerical experiments reveal that the insulating effect of sea ice causes the ocean to periodically vent out accumulated heat in the deep ocean into the atmosphere. Subjecting the model to idealized freshwater forcing mimicking Heinrich events causes modulation of the natural periodicity and produces burst patterns very similar to what is observed in temperature proxy data. Numerical experiments with the model also suggests that the characteristic period of 1,500 years is due to the geometry, or the effective heat capacity, of the ocean that comes under sea ice cover.
Quasi-bound states in periodically driven scattering
H. Landa
2015-06-29T23:59:59.000Z
We present an approach for obtaining eigenfunctions of periodically driven time-dependent Hamiltonians. Assuming an approximate scale separation between two spatial regions where different potentials dominate, we derive an explicit expansion for scattering problems with mixed cylindrical and spherical symmetry, by matching wavefunctions of a periodic linear drive in the exterior region to solutions of an arbitrary interior potential expanded in spherical waves. Using this method we study quasi-bound states of a square-well potential in three dimensions subject to an axial driving force. In the nonperturbative regime we show how eigenfunctions develop an asymptotic dressing of different partial waves, accompanied by large periodic oscillations in the angular momentum and a nonmonotonous dependence of the decay rate on the drive strength. We extend these results to the strong driving regime near a resonant intersection of the quasi-energy surfaces of two bound states of different symmetry. Our approach can be applied to general quantum scattering problems of particles subject to periodic fields.
EE 511 Solutions to Problem Set 8 1. E[Yt] = E[Xt] cos 2fct. E[Yt] is periodic with period 1/fc.
Bhashyam, Srikrishna
EE 511 Solutions to Problem Set 8 1. E[Yt] = E[Xt] cos 2fct. E[Yt] is periodic with period 1/fc. RY (t, t + ) = E[Xt+ cos 2fc(t + )Xt cos 2fct] = RX() 2 [cos 2fc + cos 2fc(2t + )] RY (t, t + ) is periodic with period 1/(2fc). Therefore, Yt is wide-sense cyclostationary with period 1/fc. E[Zt] = E[Xt]E[cos
IRC-10443: a multi-periodic SRa variable and the nature of long secondary periods in AGB stars
U. Munari; A. Siviero; P. Ochner; S. Dallaporta; C. Simoncelli
2008-10-08T23:59:59.000Z
We obtained BVIc photometry of IRC-10443 on 85 different nights distributed over two years, and in addition low resolution absolute spectro- photometry and high resolution Echelle spectroscopy. Our data show that IRC-10443, which was never studied before in any detail, is a SRa variable, characterized by Delta(B)=1.27, Delta(V)=1.14 and Delta(I)=0.70 mag amplitudes and mean values =13.75, =11.33 and =6.18 mag. Two strong periodicities are simultaneously present: a principal one of 85.5 (+/-0.2) days, and a secondary one of 620 (+/-15) days, both sinusoidal in shape, and with semi-amplitudes Delta(V)=0.41 and 0.20 mag, respectively. IRC-10443 turns out to be a M7III star, with a mean heliocentric radial velocity -28 km/s and reddened by E(B-V)=0.87, a third of which of circumstellar origin. The same 0.5 kpc distance is derived from application of the appropriate period-luminosity relations to both the principal and the secondary periods. The long secondary period causes a sinusoidal variation in color of 0.13 mag semi-amplitude in V-Ic, with IRC-10443 being bluest at maximum and reddest at minimum, and with associated changes in effective temperature and radius of 85 K and 6%, respectively. This behavior of colors argues in favor of a pulsation nature for the still mysterious long secondary periods in AGB stars.
Undulation instabilities in laterally structured magnetic multilayers T. Eimullera)
Bayreuther, Günther
Regensburg, Germany P. Guttmann Institut fu¨r Ro¨ntgenphysik, Universita¨t Go¨ttingen c/o BESSY, Albert presented here are taken at the Fe L3 edge with the full field TXM at BESSY I in Berlin,10 using a zone
Undulator-based production of polarized positrons$ G. Alexander j
McDonald, Kirk
as the International Linear Collider, ILC [1] and the Compact Linear Collider, CLIC [2]) will require the development
UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC
Bakeman, M.S.
2010-01-01T23:59:59.000Z
ultra-short, high-peak- current, electron beams are ideal for driving a compact XUV free electron laser (
Transverse Gradient Undulator Huang, Zhirong; Ding, Yuantao; /SLAC;
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23TribalInformation Access toTen Problems in Experimental Mathematics atOptimalTransportation
Modeling performance of horizontal, undulating, and multilateral wells
Kamkom, Rungtip
2009-05-15T23:59:59.000Z
.....................................................................................................1 1.2 Literature Review............................................................................................2 1.3 Objectives........................................................................................................4 1.4...........................................................18 2.3 Two-Phase Reservoirs...................................................................................21 2.4 Systematic Table for Horizontal Well Inflow Performance..........................22 2.5 Wellbore Pressure Drop...
Lateral undulation of a snake-like robot
Gupta, Amit
2007-01-01T23:59:59.000Z
Snake robots have been studied by many researchers but historically more on a theoretical basis. Recently, more and more robotic snakes have been realized in hardware. This thesis presents a design process for the electrical, ...
Knot Undulator to Generate Linearly Polarized Photons with Low...
Office of Scientific and Technical Information (OSTI)
Linearly Polarized Photons with Low on-Axis Power Density Heat load on beamline optics is a serious problem to generate pure linearly polarized photons in the third...
UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC
Bakeman, M.S.
2010-01-01T23:59:59.000Z
LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC* M.S.quasi-monoenergetic electron beams with energies up to 1high-peak- current, electron beams are ideal for driving a
Parameters of Integral Circulant Graphs and Periodic Quantum Dynamics
Nitin Saxena; Simone Severini; Igor Shparlinski
2007-03-26T23:59:59.000Z
The intention of the paper is to move a step towards a classification of network topologies that exhibit periodic quantum dynamics. We show that the evolution of a quantum system, whose hamiltonian is identical to the adjacency matrix of a circulant graph, is periodic if and only if all eigenvalues of the graph are integers (that is, the graph is integral). Motivated by this observation, we focus on relevant properties of integral circulant graphs. Specifically, we bound the number of vertices of integral circulant graphs in terms of their degree, characterize bipartiteness and give exact bounds for their diameter. Additionally, we prove that circulant graphs with odd order do not allow perfect state transfer.
Periodic Schrödinger operators with local defects and spectral pollution
Eric Cancès; Virginie Ehrlacher; Yvon Maday
2011-11-16T23:59:59.000Z
This article deals with the numerical calculation of eigenvalues of perturbed periodic Schr\\"odinger operators located in spectral gaps. Such operators are encountered in the modeling of the electronic structure of crystals with local defects, and of photonic crystals. The usual finite element Galerkin approximation is known to give rise to spectral pollution. In this article, we give a precise description of the corresponding spurious states. We then prove that the supercell model does not produce spectral pollution. Lastly, we extend results by Lewin and S\\'er\\'e on some no-pollution criteria. In particular, we prove that using approximate spectral projectors enables one to eliminate spectral pollution in a given spectral gap of the reference periodic Sch\\"odinger operator.
Periodic fluctuations in deep water formation due to sea ice
Saha, Raj
2015-01-01T23:59:59.000Z
During the last ice age several quasi-periodic abrupt warming events took place. Known as Dansgaard-Oeschger (DO) events their effects were felt globally, although the North Atlantic experienced the largest temperature anomalies. Paleoclimate data shows that the fluctuations often occurred right after massive glacial meltwater releases in the North Atlantic and in bursts of three or four with progressively decreasing strengths. In this study a simple dynamical model of an overturning circulation and sea ice is developed with the goal of understanding the fundamental mechanisms that could have caused the DO events. Interaction between sea ice and the overturning circulation in the model produces self-sustained oscillations. Analysis and numerical experiments reveal that the insulating effect of sea ice causes the ocean to periodically vent out accumulated heat in the deep ocean into the atmosphere. Subjecting the model to idealized freshwater forcing mimicking Heinrich events causes modulation of the natural p...
Period tripling causes rotating spirals in agitated wet granular layers
Kai Huang; Ingo Rehberg
2011-07-07T23:59:59.000Z
Pattern formation of a thin layer of vertically agitated wet granular matter is investigated experimentally. Rotating spirals with three arms, which correspond to the kinks between regions with different colliding phases, are the dominating pattern. This preferred number of arms corresponds to period tripling of the agitated granular layer, unlike predominantly subharmonic Faraday crispations in dry granular matter. The chirality of the spatiotemporal pattern corresponds to the rotation direction of the spirals.
Sorting by Periodic Potential Energy Landscapes: Optical Fractionation
Kosta Ladavac; Karen Kasza; David G. Grier
2003-10-16T23:59:59.000Z
Viscously damped objects driven through a periodically modulated potential energy landscape can become kinetically locked in to commensurate directions through the landscape, and thus can be deflected away from the driving direction. We demonstrate that the threshold for an object to become kinetically locked in to an array can depend exponentially on its size. When implemented with an array of holographic optical tweezers, this provides the basis for a continuous and continuously optimized sorting technique for mesoscopic objects called ``optical fractionation''.
PARC Periodical: Volume 5, Issue 3 | Photosynthetic Antenna Research Center
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Magnetic field gradients in solar wind plasma and geophysics periods
A. Bershadskii
2006-11-16T23:59:59.000Z
Using recent data obtained by Advanced Composition Explorer (ACE) the pumping scale of the magnetic field gradients of the solar wind plasma has been calculated. This pumping scale is found to be equal to 24h $\\pm$ 2h. The ACE spacecraft orbits at the L1 libration point which is a point of Earth-Sun gravitational equilibrium about 1.5 million km from Earth. Since the Earth's magnetosphere extends into the vacuum of space from approximately 80 to 60,000 kilometers on the side toward the Sun the pumping scale cannot be a consequence of the 24h-period of the Earth's rotation. Vise versa, a speculation is suggested that for the very long time of the coexistence of Earth and of the solar wind the weak interaction between the solar wind and Earth could lead to stochastic synchronization between the Earth's rotation and the pumping scale of the solar wind magnetic field gradients. This synchronization could transform an original period of the Earth's rotation to the period close to the pumping scale of the solar wind magnetic field gradients.
NASA-TM-III642 Design of Inielligent Mesoscale Periodic Array
Asher, Sanford A.
i" /} , NASA-TM-III642 Design of Inielligent Mesoscale Periodic Array Structures Utilizing Smart *National Research Council hitrodoetion Mesoscale Periodic Arlay Structures (MPAS, also known as crystalline
Non-existence of time-periodic vacuum spacetimes
Alexakis, Spyros
2015-01-01T23:59:59.000Z
We prove that smooth asymptotically flat solutions to the Einstein vacuum equations which are assumed to be periodic in time, are in fact stationary in a neighborhood of infinity. Our result applies under physically relevant regularity assumptions purely at the level of the initial data. In particular, our work removes the assumption of analyticity up to null infinity in [Bicak, Scholtz, and Tod; 2010]. The proof relies on extending a suitably constructed "candidate" Killing vector field from null infinity, via Carleman-type estimates obtained in [Alexakis, Schlue, Shao; 2013].
Beyond periodic orbits: An example in nonhydrogenic atoms
Dando, P.A.; Monteiro, T.S.; Delande, D.; Taylor, K.T. (Department of Mathematics, Royal Holloway, University of London, Egham, Surrey, TW20 0EX (United Kingdom) Laboratoire Kastler-Brossel, Universite Pierre et Marie Curie, 4 place Jussieu, F-75005 Paris (France) Department of Applied Mathematics and Theoretical Physics, Queen's University Belfast, Belfast, BT7 1NN (United Kingdom))
1995-02-13T23:59:59.000Z
The spectrum of hydrogen in a magnetic field is a paradigm of quantum chaos and may be analyzed accurately by periodic-orbit-type theories. In nonhydrogenic atoms, the core induces pure quantum effects, especially additional spectral modulations, which cannot be analyzed reliably in terms of classical orbits and their stability parameters. Provided core-scattered waves are included consistently, core-scattered modulations as well as corrected amplitudes for primitive orbits are in excellent agreement with quantum results. We consider whether these systems correspond to quantum chaos.
PARC Periodical | Vol. 6, Issue 1 | Photosynthetic Antenna Research Center
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PARC Periodical, Volume 5, Issue 2 | Photosynthetic Antenna Research Center
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PARC Periodical- Volume 5, Issue 1 | Photosynthetic Antenna Research Center
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5(Million Cubic Feet) Oregon (Including Vehicle Fuel) (Million Cubic Feet) NaturalOctoberConsumption Queueing & Running Jobs DataPeriodical | Vol.
Bott-Kitaev Periodic Table and the Diagonal Map
R. Kennedy; M. R. Zirnbauer
2014-12-15T23:59:59.000Z
Building on the 10-way symmetry classification of disordered fermions, the authors have recently given a homotopy-theoretic proof of Kitaev's "Periodic Table" for topological insulators and superconductors. The present paper offers an introduction to the physical setting and the mathematical model used. Basic to the proof is the so-called Diagonal Map, a natural transformation akin to the Bott map of algebraic topology, which increases by one unit both the momentum-space dimension and the symmetry index of translation-invariant ground states of gapped free-fermion systems. This mapping is illustrated here with a few examples of interest.
Forced Oscillations in Fluid Tori and Quasi-Periodic Oscillations
William H. Lee
2005-10-19T23:59:59.000Z
The kilo-Hertz Quasi--Periodic Oscillations in X-ray binaries could originate within the accretion flow, and be a signature of non--linear fluid oscillations and mode coupling in strong gravity. The possibility to decipher these systems will impact our knowledge of fundamental parameters such as the neutron star mass, radius, and spin. Thus they offer the possibility to constrain the nuclear equation of state and the rotation parameter of stellar--mass black holes. We review the general properties of these oscillations from a hydrodynamical point of view, when the accretion flow is subject to external perturbations and summarize recent results.
Ferromagnetism in the two-dimensional periodic Anderson model
Batista, C. D.; Bonca, J.; Gubernatis, J. E.
2001-05-01T23:59:59.000Z
Using the constrained-path Monte Carlo method, we studied the magnetic properties of the two-dimensional periodic Anderson model for electron fillings between 1/4 and 1/2. We also derived two effective low-energy theories to assist in interpreting the numerical results. For 1/4 filling, we found that the system can be a Mott or a charge-transfer insulator, depending on the relative values of the Coulomb interaction and the charge-transfer gap between the two noninteracting bands. The insulator may be a paramagnet or antiferromagnet. We concentrated on the effect of electron doping on these insulating phases. Upon doping we obtained a partially saturated ferromagnetic phase for low concentrations of conduction electrons. If the system were a charge-transfer insulator, we would find that the ferromagnetism is induced by the well-known Ruderman-Kittel-Kasuya-Yosida interaction. However, we found a novel correlated hopping mechanism inducing the ferromagnetism in the region where the nondoped system is a Mott insulator. Our regions of ferromagnetism spanned a much smaller doping range than suggested by recent slave boson and dynamical mean-field theory calculations, but they were consistent with that obtained by density-matrix renormalization group calculations of the one-dimensional periodic Anderson model.
Turbulent transport phenomena in a channel with periodic rib turbulators
Liou, T.M.; Hwang, J.J.; Chen, S.H. (National Tsing Hua University, Hsinchu (Taiwan))
1992-09-01T23:59:59.000Z
Periodic fully developed turbulent flow in a 2D channel with rib turbulators on two opposite walls has been studied numerically and experimentally. In numerical predictions, an algebraic Reynolds stress turbulence model is adopted, and a smoothed hybrid central/skew upstream difference scheme is developed. In experiments, the laser-Doppler velocimetry and laser holographic interferometry are employed to measure the local flow and heat transfer characteristics. The results are obtained with the ratio of pitch to rib height 5, 10, 15, and 20, for Reynolds number of 3.3 x 10 exp 4 and are presented in terms of the reattachment length, mean velocity and turbulent kinetic energy profiles, isotherm patterns, and distributions of local pressure recovery and Nusselt number. A detailed comparison with experimental data shows that the present calculations have an improvement over the previous work in the prediction of periodic ribbed-wall flow and heat transfer. In addition, regions susceptible to hot spots are identified by examining the distributions of the local Nusselt number. Furthermore, the enhancement of mean Nusselt number is documented in terms of relative contributions of the increased turbulence intensity and surface area provided by the ribs. 32 refs.
Periodicity of the solar full-disk magnetic fields
Xiang, N. B.; Qu, Z. N.; Zhai, Q. [National Astronomical Observatories/Yunnan Observatory, CAS, Kunming 650011 (China)
2014-07-01T23:59:59.000Z
A full-disk solar magnetogram has been measured each day since 1970 January 19, and the daily Magnetic Plage Strength Index (MPSI) and the daily Mount Wilson Sunspot Index (MWSI) were calculated for each magnetogram at the Mount Wilson Observatory. The MPSI and MWSI are used to investigate the periodicity of the solar full-disk magnetic activity through autocorrelation analyses. Just two periods, the solar cycle and the rotation cycle, are determined in both the MPSI (the solar full-disk weak magnetic field activity) and MWSI (the solar full-disk strong magnetic field activity) with no annual signal found. The solar cycle for MPSI (10.83 yr) is found to be obviously longer than that for MWSI (9.77 yr). The rotation cycle is determined to be 26.8 ± 0.63 sidereal days for MPSI and 27.4 ± 2.4 sidereal days for MWSI. The rotation cycle length for MPSI is found to fluctuate around 27 days within a very small amplitude, but for MWSI it obviously temporally varies with a rather large amplitude. The rotation cycle for MWSI seems longer near solar minimum than at solar maximum. Cross-correlation analyses of daily MPSI and MWSI are carried out, and it is inferred that the MPSI components partly come from relatively early MWSI measurements.
Broader source: Energy.gov [DOE]
Energy Conservation Program for Consumer Products: Test Procedures for Furnaces and Boilers, Comment Period Extension
Dynamically tunable Fano resonance in periodically asymmetric graphene nanodisk pair
Zhang, Zhengren; Fan, Yuancheng; Yin, Pengfei; Zhang, Liwei; Shi, Xi
2015-01-01T23:59:59.000Z
We present a dynamically frequency tunable Fano resonance planar device composed of periodically asymmetric graphene nanodisk pair for the mid-infrared region. There are two kinds of modes in this structure, that is, the symmetric mode and the antisymmetric mode. The resonance coupling between the symmetric and antisymmetric modes creates a classical Fano resonance. Both of the Fano resonance amplitude and frequency of the structure can be dynamically controlled by varying the Fermi energy of graphene. Resonance transition in the structure is studied to reveal the physical mechanism behind the dynamically tunable Fano resonance. The features of the Fano resonant graphene nanostructures should have promising applications in tunable THz filters, switches, and modulators.
Chaotic dynamics in a periodically driven spin-1 condensate
Cheng Jing [Department of Physics, South China University of Technology, Guangzhou 510640 (China); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China)
2010-02-15T23:59:59.000Z
We use periodically modulated magnetic fields to drive spin-1 Bose-Einstein condensates (BECs) and study the corresponding spin-mixing dynamics. Due to the time-dependent driving, this system permits chaotic dynamics depending on the drive parameters, which could not occur in previous studies. From the investigation of the Poincare sections, we find there exist complex trajectories in the phase space, leading to very complicated structures of the phase space with mixed regular and chaotic regions. By calculating the quasienergy levels of the corresponding Floquet operators, the signatures of quantum chaos are also found in this system. The level spacing distribution is very close to the Poisson distribution or Wigner distribution when the corresponding classical dynamics is regular or chaotic.
Periodic relativity: deflection of light, acceleration, rotation curves
Vikram H. Zaveri
2014-12-08T23:59:59.000Z
Vectorial analysis relating to derivation of deflection of light is presented. Curvilinear acceleration is distinguished from the Newtonian polar conic acceleration. The difference between the two is due to the curvature term. Lorentz invariant expression for acceleration is derived. A physical theory of rotation curves of galaxies based on second solution to Einstein's field equation is presented. Theory is applied to Milky Way, M31, NGC3198 and Solar system. Modified Kepler's third law yields correct orbital periods of stars in a galaxy. Deviation factor in the line element of the theory happens to be the ratio of the Newtonian gravitational acceleration to the measured acceleration of the star in the galaxy. Therefore this deviation factor can replace the MOND function.
Desingularization of periodic vortex sheet roll-up
Krasny, R.
1986-08-01T23:59:59.000Z
The equations governing periodic vortex sheet roll-up from analytic initial data are desingularized. Linear stability analysis shows that this diminishes the vortex sheet model's short wavelength instability, yielding a numerically more tractable set of equations. Computational evidence is presented which indicates that this approximation converges, beyond the critical time of singularity formation in the vortex sheet, if the mesh is refined and the smoothing parameter is reduced in the proper order. The results suggest that the vortex sheet rolls up into a double branched spiral past the critical time. It is demonstrated that either higher machine precision or a spectra filter can be used to maintain computational accuracy as the smoothing parameter is decreased. Some conjectures on the model's long time asymptotic state are given.
Variable Selection and Inference for Multi-period Forecasting Problems
Pesaran, M Hashem; Pick, Andreas; Timmermann, Allan
?t,x?t)?. Multi-period forecasts of yt can then be obtained iteratively using a conventional VAR of the form zt = µz + ( Ap(L) Bq(L) Cr(L) Ds(L) ) zt?1 + ?t, (10) where p and q are the lag order of yt and xt in the equation for yt and r and s is the lag order... , i.e. Cr(L) and Bq(L) in particular. To deal with this issue, a conditional factor-augmentation approach can be used. In this approach, the large-dimensional xt-vector is condensed into a subset of factors, fˆ t, of dimension m < M , used to summarize...
Magnetic helicity evolution in a periodic domain with imposed field
Axel Brandenburg; William H. Matthaeus
2004-05-24T23:59:59.000Z
In helical hydromagnetic turbulence with an imposed magnetic field (which is constant in space and time) the magnetic helicity of the field within a periodic domain is no longer an invariant of the ideal equations. Alternatively, there is a generalized magnetic helicity that is an invariant of the ideal equations. It is shown that this quantity is not gauge invariant and that it can therefore not be used in practice. Instead, the evolution equation of the magnetic helicity of the field describing the deviation from the imposed field is shown to be a useful tool. It is demonstrated that this tool can determine steady state quenching of the alpha-effect. A simple three-scale model is derived to describe the evolution of the magnetic helicity and to predict its sign as a function of the imposed field strength. The results of the model agree favorably with simulations.
A Radio SETI Campaign for microsec-sec Periodic Signals
Harp, G R; Astorga, Alfredo; Arbunich, Jack; Hightower, Kristin; Meitzner, Seth; Barott, W C; Nolan, Michael C; Messerschmitt, D G; Vakoch, Douglas A; Shostak, Seth; Tarter, J C
2015-01-01T23:59:59.000Z
We report a novel radio autocorrelation (AC) search for extraterrestrial intelligence (SETI). For selected frequencies across the terrestrial microwave window (1-10 GHz) observations were conducted at the Allen Telescope Array to identify artificial non-sinusoidal periodic signals with radio bandwidths greater than 1 kHz, which are capable of carrying substantial messages with symbol-rates from 10-10e6 Hz. Out of 243 observations, about half (101) were directed toward sources with known continuum flux greater than 1 Jy (quasars, pulsars, supernova remnants and masers), based on the hypothesis that they might harbor heretofore undiscovered natural or artificial, repetitive, phase or frequency modulation. The rest of the targets were mostly toward exoplanet stars and similarly interesting targets from the standpoint of SETI. This campaign rules out several previously untested hypotheses relating to the number of artificially modulated "natural" sources. Since we are using a phase sensitive detector, these obser...
IUPAC Periodic Table of Isotopes for the Educational Community
Holden N. E.; Holden,N.E.; Coplen,T.B.
2012-07-15T23:59:59.000Z
John Dalton first proposed the concept of atomic weights of the elements in the first decade of the nineteenth century. These atomic weights of the chemical elements were thought of as constants of nature, similar to the speed of light. Dmitri Mendeleev arranged the atomic weights of the elements in ascending order of value and used the systematic variation of their chemical properties to produce his Periodic Table of the Elements in 1869. Measurement of atomic weight values became an important chemical activity for a century and a half. Theodore Richards received a Noble Prize for his work in this area. In 1913, Fredrick Soddy found a species of radium, which had an atomic weight value of 228, compared to the familiar radium gas value of 226. Soddy coined the term 'isotope' (Greek for 'in the same place') to account for this second atomic weight value in the radium position of the Periodic Table. Both of these isotopes of radium are radioactive. Radioactive isotopes are energetically unstable and will decay (disintegrate) over time. The time it takes for one half of a sample of a given radioactive isotope to decay is the half-life of that isotope. In addition to having different atomic weight values, radium-226 and radium-228 also have different half-life values. Around the same time as Soddy's work, J.J. Thomson (discoverer of the electron) identified two stable (non-radioactive) isotopes of the same element, neon. Over the next 40 years, the majority of the known chemical elements were found to have two or more stable (or long-lived radioactive isotopes that contribute significantly to the determination of the atomic weights of the elements).
Physics Division progress report for period ending September 30, 1984
Livingston, A.B. (ed.)
1985-01-01T23:59:59.000Z
The research activities of the Division are centered primarily in three areas: experimental nuclear physics, experimental atomic physics, and theoretical nuclear and atomic physics. The largest of these efforts, experimental nuclear physics, is dominated by the heavy ion research program. A major responsibility under this program is the operation of the Holifield Heavy Ion Research Facility as a national user facility. During the period of this report, the facility has begun routine operation for the experimental program. The experimental atomic physics program has two components: the accelerator-based studies of basic collisional phenomena and the studies in support of the controlled fusion program. Also associated with the fusion-related studies are a plasma diagnostics program and the operation of an atomic physics data center. The theoretical physics program, both nuclear and atomic, is covered. This program has benefited this year from the success of the VAX-AP computer system and from the increase in manpower provided by the ORNL/University of Tennessee Distinguished Scientist Program. Smaller programs in applications and high-energy physics are summarized. During the period of this report, we continued to explore possible future extensions of the Holifield Facility. We retain a strong interest in a relativistic heavy-ion collider in the 10 x 10 GeV/nuclear energy range. The ideas for such a facility, described in last year's report, have been modified to utilize the HHIRF 25 MV tandem accelerator as the first stage. Finally, the report concludes with some general information on publications, Division activities, and personnel changes.
TESLA-FEL 2004-02 The Potential for the Development of the
TESLA-FEL 2004-02 The Potential for the Development of the X-Ray Free Electron Laser E.L. Saldin, E Abstract X-ray photon beam from a SASE FEL undulator is in principle a single user tool, just like the SASE FEL with three undulators which have different period and tunable gap. All electrons
Physics division. Progress report for period ending September 30, 1996
Ball, S.J. [ed.
1997-04-01T23:59:59.000Z
This report covers the research and development activities of the Physics Division for the 1995 and 1996 fiscal years, beginning October 1, 1994, and ending September 30, 1996. The activities of the Division continue to be concentrated in the areas of experimental nuclear physics, experimental atomic physics, and theoretical nuclear and atomic physics. In addition, there are smaller programs in plasma diagnostics and data compilation and evaluation. During the period of this report, there has been considerable success in bringing the Holifield Radioactive Ion Beam Facility (HRIBF) into routine operation. The budgets of the nuclear physics portion of the Division have increased each year in nearly all areas, and several new members have been added to the Division research and development staff. On August 30, 1996, the HRIBF successfully accelerated its first radioactive ion beams, {sup 69}As and {sup 70}As. Prior to this, the heart of the facility, the RIB injector system, was completed, including installation of a remote handling system for the target/ion source assembly. Target and ion source development is likely to be the technical key to success of the HRIBF. We have expanded our efforts in those development areas. Of special note is the development of highly permeable composite targets which have now been shown to allow release of difficult-to-produce radioactive ions such as {sup 17,18}F. A summary of the HRIBF work is provided in Chapter 1, along with supporting activities of the Joint Institute for Heavy Ion Research.
A renewal theory approach to periodic copolymers with adsorption
Francesco Caravenna; Giambattista Giacomin; Lorenzo Zambotti
2007-10-24T23:59:59.000Z
We consider a general model of a heterogeneous polymer chain fluctuating in the proximity of an interface between two selective solvents. The heterogeneous character of the model comes from the fact that the monomer units interact with the solvents and with the interface according to some charges that they carry. The charges repeat themselves along the chain in a periodic fashion. The main question concerning this model is whether the polymer remains tightly close to the interface, a phenomenon called localization, or whether there is a marked preference for one of the two solvents, thus yielding a delocalization phenomenon. In this paper, we present an approach that yields sharp estimates for the partition function of the model in all regimes (localized, delocalized and critical). This, in turn, makes possible a precise pathwise description of the polymer measure, obtaining the full scaling limits of the model. A key point is the closeness of the polymer measure to suitable Markov renewal processes, Markov renewal theory being one of the central mathematical tools of our analysis.
Large deviations for quasi-periodic cocycles with singularities
Pedro Duarte; Silvius Klein
2015-07-10T23:59:59.000Z
We derive large deviations type (LDT) estimates for linear cocycles over an ergodic multifrequency torus translation. These models are called quasi-periodic cocycles. We make the following assumptions on the model: the translation vector satisfies a generic Diophantine condition, and the fiber action is given by a matrix valued analytic function of several variables which is not identically singular. The LDT estimates obtained here depend on some uniform measurements on the cocycle. Our general results derived in [9] regarding the continuity properties of the Lyapunov exponents (LE) and of the Oseledets filtration and decompositions are then applicable, and we obtain local weak-Holder continuity of these quantities in the presence of gaps in the Lyapunov spectrum. The main new feature of this work is allowing a cocycle depending on several variables to have singularities, i.e. points of non invertibility. This requires a careful analysis of the set of zeros of certain analytic functions of several variables and of the singularities (i.e. negative infinity values) of pluri-subharmonic functions related to the iterates of the cocycle. A refinement of this method in the one variable case leads to a stronger LDT estimate and in turn to a stronger, nearly-Holder modulus of continuity of the LE, Oseledets filtration and Oseledets decomposition. This is a draft of a chapter in our forthcoming research monograph [9].
Nonlinear Dynamics, Magnitude-Period Formula and Forecasts on Earthquake
Yi-Fang Chang
2008-02-02T23:59:59.000Z
Based on the geodynamics, an earthquake does not take place until the momentum-energy excess a faulting threshold value of rock due to the movement of the fluid layer under the rock layer and the transport and accumulation of the momentum. From the nonlinear equations of fluid mechanics, a simplified nonlinear solution of momentum corresponding the accumulation of the energy could be derived. Otherwise, a chaos equation could be obtained, in which chaos corresponds to the earthquake, which shows complexity on seismology, and impossibility of exact prediction of earthquakes. But, combining the Carlson-Langer model and the Gutenberg-Richter relation, the magnitude-period formula of the earthquake may be derived approximately, and some results can be calculated quantitatively. For example, we forecast a series of earthquakes of 2004, 2009 and 2014, especially in 2019 in California. Combining the Lorenz model, we discuss the earthquake migration to and fro. Moreover, many external causes for earthquake are merely the initial conditions of this nonlinear system.
The periodic standing-wave approximation: post-Minkowski computation
Christopher Beetle; Benjamin Bromley; Napoleón Hernández; Richard H. Price
2007-08-08T23:59:59.000Z
The periodic standing wave method studies circular orbits of compact objects coupled to helically symmetric standing wave gravitational fields. From this solution an approximation is extracted for the strong field, slowly inspiralling motion of black holes and binary stars. Previous work on this model has dealt with nonlinear scalar models, and with linearized general relativity. Here we present the results of the method for the post-Minkowski (PM) approximation to general relativity, the first step beyond linearized gravity. We compute the PM approximation in two ways: first, via the standard approach of computing linearized gravitational fields and constructing from them quadratic driving sources for second-order fields, and second, by solving the second-order equations as an ``exact'' nonlinear system. The results of these computations have two distinct applications: (i) The computational infrastructure for the ``exact'' PM solution will be directly applicable to full general relativity. (ii) The results will allow us to begin supplying initial data to collaborators running general relativistic evolution codes.
Periodically-driven quantum matter: the case of resonant modulations
N. Goldman; J. Dalibard; M. Aidelsburger; N. R. Cooper
2015-03-06T23:59:59.000Z
Quantum systems can show qualitatively new forms of behavior when they are driven by fast time-periodic modulations. In the limit of large driving frequency, the long-time dynamics of such systems can often be described by a time-independent effective Hamiltonian, which is generally identified through a perturbative treatment. Here, we present a general formalism that describes time-modulated physical systems, in which the driving frequency is large, but resonant with respect to energy spacings inherent to the system at rest. Such a situation is currently exploited in optical-lattice setups, where superlattice (or Wannier-Stark-ladder) potentials are resonantly modulated so as to control the tunneling matrix elements between lattice sites, offering a powerful method to generate artificial fluxes for cold-atom systems. The formalism developed in this work identifies the basic ingredients needed to generate interesting flux patterns and band structures using resonant modulations. Additionally, our approach allows for a simple description of the micro-motion underlying the dynamics; we illustrate its characteristics based on diverse dynamic-lattice configurations. It is shown that the impact of the micro-motion on physical observables strongly depends on the implemented scheme, suggesting that a theoretical description in terms of the effective Hamiltonian alone is generally not sufficient to capture the full time-evolution of the system.
A. UDALSKI; M. KUBIAK; M. SZYMANSKI; J. KALUZNY; M. MATEO; W. KRZEMINSKI
1995-01-09T23:59:59.000Z
This paper is the first part of the Catalog of Periodic Variable Stars in the Galactic bulge. The Catalog is based on observations collected during the OGLE microlensing search. 213 periodic variable stars brighter than I=18 mag: 31 pulsating, 116 eclipsing and 66 miscellaneous type variables from the Baade's Window BWC field are presented. Periodic variable stars from remaining 20 fields will be presented in similar form in the next parts of the Catalog. The Catalog as well as observations of all periodic variable objects are available to astronomical community over the Internet network.
Geothermal R and D Project report for period April 1, 1976 to...
report for period April 1, 1976 to June 30, 1976 Jump to: navigation, search OpenEI Reference LibraryAdd to library Report: Geothermal R and D Project report for period April 1,...
The Near-infrared Period-luminosity Relations of Cepheids in the Large Magellanic Cloud
Mahzooni, Salma
2011-08-08T23:59:59.000Z
We present near-infrared (J & Ks) observations of Cepheids in the Large Magellanic Cloud. The goals of these observations are to better characterize the Cepheid Period-Luminosity relation at these wavelengths, especially for periods below 10 days...
Periodic solutions of even Hamiltonian systems on Thomas Bartsch & ZhiQiang Wang 1
Wang, Zhi-Qiang
Periodic solutions of even Hamiltonian systems on the torus Thomas Bartsch & ZhiQiang Wang 1 and their hospitality. #12; 2 Thomas Bartsch & ZhiQiang Wang 1 Introduction Hamiltonian systems with periodic
Taxonomy of periodic nets and the design of materials Olaf Delgado-Friedrichs,a
Yaghi, Omar M.
Taxonomy of periodic nets and the design of materials Olaf Delgado-Friedrichs,a Michael O classification (taxonomy) of polyhedra and periodic nets that is appropriate for identifying the structures
Victoria, University of
A New Methodology for Frequency Domain Analysis of Wave Energy Converters with Periodically Varying Methodology for Frequency Domain Analysis of Wave Energy Converters with Periodically Varying Physical of Mechanical Engineering) ABSTRACT Within a wave energy converter's operational bandwidth, device operation
Klages, Rainer
Lyapunov instability for a periodic Lorentz gas thermostated by deterministic scattering K assess the nonlinear properties of this dynamical system by numerically calculating its Lyapunov exponents. Based on a revised method for computing Lyapunov exponents, which employs periodic
Steady-State Electrical Conduction in the Periodic Lorentz Gas
N. I. Chernov; G. L. Eyink; J. L. Lebowitz; Ya. G. Sinai
1993-02-08T23:59:59.000Z
We study nonequilibrium steady states in the Lorentz gas of periodic scatterers when an external field is applied and the particle kinetic energy is held fixed by a ``thermostat'' constructed according to Gauss' principle of least constraint (a model problem previously studied numerically by Moran and Hoover). The resulting dynamics is reversible and deterministic, but does not preserve Liouville measure. For a sufficiently small field, we prove the following results: (1) existence of a unique stationary, ergodic measure obtained by forward evolution of initial absolutely continuous distributions, for which the Pesin entropy formula and Young's expression for the fractal dimension are valid; (2) exact identity of the steady-state thermodyamic entropy production, the asymptotic decay of the Gibbs entropy for the time-evolved distribution, and minus the sum of the Lyapunov exponents; (3) an explicit expression for the full nonlinear current response (Kawasaki formula); and (4) validity of linear response theory and Ohm's transport law, including the Einstein relation between conductivity and diffusion matrices. Results (2) and (4) yield also a direct relation between Lyapunov exponents and zero-field transport (=diffusion) coefficients. Although we restrict ourselves here to dimension $d=2,$ the results carry over to higher dimensions and to some other physical situations: e.g. with additional external magnetic fields. The proofs use a well-developed theory of small perturbations of hyperbolic dynamical systems and the method of Markov sieves, an approximation of Markov partitions. In our context we discuss also the van Kampen objection to linear response theory, which, we point out, overlooks the ``structural stability'' of strongly hyperbolic flows.
Outburst-related period changes of recurrent nova CI aquilae
Wilson, R. E.; Honeycutt, R. K., E-mail: honey@astro.indiana.edu, E-mail: rewilson@ufl.edu [Astronomy Department, Indiana University, Swain Hall West, Bloomington, IN 47405 (United States)
2014-11-01T23:59:59.000Z
Pre-outburst and post-outburst light curves and post-outburst eclipse timings are analyzed to measure any period (P) change related to nova CI Aql's outburst of early 2000 and a mean post-outburst dP/dt, which then lead to estimates of the accreting component's rate of mass (M) change and its overall outburst-related change of mass over roughly a decade of observations. We apply a recently developed procedure for unified analysis of three timing-related data types (light curves, radial velocities, and eclipse timings), although with only light curves and timings in this case. Fits to the data are reasonably good without need for a disk in the light-curve model, although the disk certainly exists and has an important role in our post-outburst mass flow computations. Initial experiments showed that, although there seems to be an accretion hot spot, it has essentially no effect on derived outburst-related ?P or on post-outburst dP/dt. Use of atomic time (HJED) in place of HJD also has essentially nil effect on ?P and dP/dt. We find ?P consistently negative in various types of solutions, although at best only marginally significant statistically in any one experiment. Pre-outburst HJD {sub 0} and P results are given, as are post-outburst HJD {sub 0}, P, and dP/dt, with light curves and eclipse times as joint input, and also with only eclipse time input. Post-outburst dP/dt is negative at about 2.4?. Explicit formulae for mass transfer rates and epoch-to-epoch mass change are developed and applied. A known offset in the magnitude zero point for 1991-1994 is corrected.
DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JUNE 1, 2001 THROUGH SEPTEMBER 30, 2001
L.C. BROWN
2001-09-30T23:59:59.000Z
OAK-B135 DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JUNE 1, 2001 THROUGH SEPTEMBER 30, 2001
Hall, Rachel W.
in Hz and BPM. Is the frequency within the range of human hearing? Answer. The periodic wave frequency is 1/0.01 = 100 Hz = 6000 BPM. 2. Functions. (a) For each function, determine whether and frequency =3 BPM (2) amplitude = 10 and fundamental period = 0.005 seconds. Answer. (1) since 3 BPM = 180 Hz
Zhang, Dingzong; Wang, Yanhui; Wang, Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
2013-06-15T23:59:59.000Z
Period-doubling and chaos phenomenon have been frequently observed in atmospheric-pressure dielectric-barrier discharges. However, how a normal single period discharge bifurcates into period-doubling state is still unclear. In this paper, by changing the driving frequency, we study numerically the transition mechanisms from a normal single period discharge to a period-doubling state using a one-dimensional self-consistent fluid model. The results show that before a discharge bifurcates into a period-doubling state, it first deviates from its normal operation and transforms into an asymmetric single period discharge mode. Then the weaker discharge in this asymmetric discharge will be enhanced gradually with increasing of the frequency until it makes the subsequent discharge weaken and results in the discharge entering a period-doubling state. In the whole transition process, the spatial distribution of the charged particle density and the electric field plays a definitive role. The conclusions are further confirmed by changing the gap width and the amplitude of the applied voltage.
Holocene climate instability during the termination of the African Humid Period
Renssen, Hans
Holocene climate instability during the termination of the African Humid Period H. Renssen January 2003; published 25 February 2003. [1] The termination of the Holocene African Humid Period ($9. Goosse, Holocene climate instability during the termination of the African Humid Period, Geophys. Res
E ective boundary conditions for laminar ows over periodic rough boundaries
Achdou, Yves
E#27;ective boundary conditions for laminar #29;ows over periodic rough boundaries Yves Achdou #3 are proposed for a laminar #29;ow over a rough wall with periodic roughness elements. These e#27;ective is such an approach ? In this paper, we wish to answer these questions for laminar #29;ows over periodic rough walls
Detection and discrimination of the periodicity of prime numbers by discrete Fourier transform
Levente Csoka
2015-01-27T23:59:59.000Z
A novel representation of a quasi-periodic modified von Mangoldt function L(n) on prime numbers and its decomposition into Fourier series has been investigated. We focus on some particular quantities characterizing the modified von Mangoldt function. The results indicate that prime number progression can be decomposed into periodic sequences. The main approach is to decompose it into sin or cosine function. Basically, it is applied to extract hidden periodicities in seemingly quasi periodic prime function. Numerical evidences were provided to confirm the periodic distribution of primes.
The periods of the intermediate polar RX J0153.3+7446
A. J. Norton; J. D. Tanner
2005-12-06T23:59:59.000Z
We present the first optical photometry of the counterpart to the candidate intermediate polar RX J0153.3+7446. This reveals an optical pulse period of 2333s +/- 5s. Reanalysis of the previously published ROSAT X-ray data reveals that the true X-ray pulse period is probably 1974s +/- 30s, rather than the 1414 s previously reported. Given that the previously noted orbital period of the system is 3.94 h, we are able to identify the X-ray pulse period with the white dwarf spin period and the optical pulse period with the rotation period of the white dwarf in the binary reference frame, as commonly seen in other intermediate polars. We thus confirm that RX J0153.3+7446 is indeed a typical intermediate polar.
[2008, 23pp]---On certain period relations for cusp forms on GL_n.pdf
2008-07-24T23:59:59.000Z
International Mathematics Research Notices, Vol. 2008, Article ID rnn077, .... sponds to a Hilbert modular form of CM type, then our period relations are formally ...
EIS-0466: Re-opening of Public Scoping Period and Announcement...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Public Scoping Meetings Continued Operation of the Sandia National Laboratories, New Mexico Comment Period Ends: 9122011 Submit Comments to: Ms. Jeanette Norte NNSA Sandia...
EIS-0299: Notice of Extension of Comment Period for the Environmental...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Impact Statement Proposed Production of Plutonium-238 for Use in Advanced Radioisotope Power Systems for Future Space Missions DOE is extending the public scoping period on the...
A Low-Cost, High-Efficiency Periodic Flow Gas Turbine for Distributed Energy Generation
Dr. Adam London
2008-06-20T23:59:59.000Z
The proposed effort served as a feasibility study for an innovative, low-cost periodic flow gas turbine capable of realizing efficiencies in the 39-48% range.
Computer Assisted 'Proof' of the Global Existence of Periodic Orbits in the Rössler System
A. E. Botha; W. Dednam
2014-08-14T23:59:59.000Z
The numerical optimized shooting method for finding periodic orbits in nonlinear dynamical systems was employed to determine the existence of periodic orbits in the well-known R\\"ossler system. By optimizing the period $T$ and the three system parameters, $a$, $b$ and $c$, simultaneously, it was found that, for any initial condition $(x_0,y_0,z_0) \\in \\Re^3$, there exists at least one set of optimized parameters corresponding to a periodic orbit passing through $ (x_0,y_0,z_0)$. After a discussion of this result it was concluded that its analytical proof may present an interesting new mathematical challenge.
EIS-0385: Notice to Extend the Public Scoping Period and Reschedule...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
to Extend the Public Scoping Period and Reschedule Public Scoping Meetings Strategic Petroleum Reserve Due to the extraordinary circumstances created by Hurricane Katrina in the...
Measuring the rotation period distribution of field M-dwarfs with Kepler
McQuillan, Amy; Mazeh, Tsevi
2013-01-01T23:59:59.000Z
We have analysed 10 months of public data from the Kepler space mission to measure rotation periods of main-sequence stars with masses between 0.3 and 0.55 M_sun. To derive the rotational period we introduce the autocorrelation function and show that it is robust against phase and amplitude modulation and residual instrumental systematics. Of the 2483 stars examined, we detected rotation periods in 1570 (63.2%), representing an increase of a factor ~ 30 in the number of rotation period determination for field M-dwarfs. The periods range from 0.37-69.7 days, with amplitudes ranging from 1.0-140.8 mmags. The rotation period distribution is clearly bimodal, with peaks at ~ 19 and ~ 33 days, hinting at two distinct waves of star formation, a hypothesis that is supported by the fact that slower rotators tend to have larger proper motions. The two peaks of the rotation period distribution form two distinct sequences in period-temperature space, with the period decreasing with increasing temperature, reminiscent of ...
EIS-0250-S2 and EIS-0369: Notice of Public Comment Period Extension...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Notice of Public Comment Period Extension and Additional Public Meeting Supplemental Yucca Mountain Rail Corridor and Rail Alignment The Department of Energy announced an...
DOE Extends Comment Period on Notice of Inquiry Under the Energy...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Act of 2007, which implements the Convention on Supplementary Compensation for Nuclear Damage. The public comment period will be extended to October 27, 2010. The signed extension...
Efficient Solvers for Nonlinear Time-Periodic Eddy Current F. Bachinger
Schoeberl, Joachim
Efficient Solvers for Nonlinear Time-Periodic Eddy Current Problems F. Bachinger U. Langer J. Sch-periodic eddy current problems, ranging from the description of the nonlinearity to an efficient solution setup, the magnetic field and the thereby generated eddy currents hardly penetrate into conducting
Characterization of LMS and DMR Beamformers in the Presence of Loud Periodic Interferers
George Mason University
Characterization of LMS and DMR Beamformers in the Presence of Loud Periodic Interferers Geoffrey C introduced loud impulsive periodic interferers into these systems. Standard LMS adaptive beamforming interference. 1. INTRODUCTION Adaptive Least Mean-Square (LMS) beamformers are efficient algorithms, providing
Emergence of unsteady dark solitary waves from coalescing spatially-periodic patterns
Bridges, Tom
Emergence of unsteady dark solitary waves from coalescing spatially-periodic patterns Thomas J of the defocussing nonlinear Schrödinger equation. In this paper the interest is in a mechanism for the emergence is on the periodic state at innity as the generator. It is shown that a natural mechanism for the emergence
Margaliot, Michael
1 Entrainment to Periodic Initiation and Transition Rates in a Computational Model for Gene, the biological system must entrain or phase-lock to the periodic excitation. Entrainment is also important in synthetic biology. For example, connecting several artificial biological systems that entrain to a common
Sontag, Eduardo
Entrainment to Periodic Initiation and Transition Rates in a Computational Model for Gene to the solar day. In the terminology of systems theory, the biological system must entrain or phase-lock to the periodic excitation. Entrainment is also important in synthetic biology. For example, connecting several
Semi-automatic Construction of Cross-period Thesaurus Chaya Liebeskind, Ido Dagan, Jonathan Schler
Wintner, Shuly
Semi-automatic Construction of Cross-period Thesaurus Chaya Liebeskind, Ido Dagan, Jonathan Schler-period (Diachronic) Thesaurus Automatic generation of candidates Research objective Our task: · Support searches of cultural resources · High-quality diachronic thesaurus construction Semi-automatic setting Hardly explored
Attractiveness of periodic orbits in parametrically forced systems with time-increasing friction
Attractiveness of periodic orbits in parametrically forced systems with time-increasing friction-dimensional systems subject to a periodic force and study numer- ically how a time-varying friction affects oscillator in the presence of friction. We find that, if the damping coefficient increases in time up
Periodic migration in a physical model of cells on micropatterns Brian A. Camley,1, 2
Li, Bo
Periodic migration in a physical model of cells on micropatterns Brian A. Camley,1, 2 Yanxiang Zhao, bipedal motion, and periodic migration, in which the cell crawls persistently in one direction before-dimensional extracellular ma- trix (ECM). However, cells in ECM often exhibit qualitatively different modes of migration
Stable all-optical limiting in nonlinear periodic structures. I. Analysis
Pelinovsky, Dmitry
Stable all-optical limiting in nonlinear periodic structures. I. Analysis Dmitry Pelinovsky consider propagation of coherent light through a nonlinear periodic optical structure consisting of two al-dependent dy- namics. We find the domain for existence of true all-optical limiting when the input
Comparison of quantization of charge transport in periodic and open pumps
Comparison of quantization of charge transport in periodic and open pumps G.M. Graf and G. Ortelli the charges transported in two systems, a spatially periodic and an open quantum pump, both depending physical situations become the same, i.e., that of a large open pump. 1 Introduction In this note we
Temporal evolution of long-timescale periodicities in ULX NGC 5408 X-1
An, Tao; Wang, Jun-Yi
2015-01-01T23:59:59.000Z
Context. NGC 5408 X-1 is one of the few ultraluminous X-ray sources with an extensive monitoring program in X-rays (a temporal baseline of 4.2 yr), making it one of the most suitable candidates to study the long-timescale quasi-periodic oscillations (QPOs). Aims. Previous timing analysis of the Swift data of NGC 5408 X-1 led to detection of multiple periodicities ranging from 2.6 d to 230 d. In this paper, we focus on the statistical significance and the temporal evolution of these periodicities. Methods. A time-series analysis technique in the time-frequency domain, the weighted wavelet Z-transform (WWZ), was employed to identify the periodicities and trace their variations with time. Results. Three periodic components were detected from the WWZ periodogram, corresponding to periods of 2.65$\\pm$0.01 d, 115.4$\\pm$14.4 d and 189.1$\\pm$15.2 d. All three have statistical significance higher than 99.74%. The 2.65-d periodicity is quite stable in the majority of the light curve. The 115-d periodicity is the most p...
Multi-Period Production Capacity Planning for Integrated Product and Production System Design*
Saitou, Kazuhiro "Kazu"
Multi-Period Production Capacity Planning for Integrated Product and Production System Design* Emre.ac.uk kazu@umich.edu .Abstract This paper presents a simulation-based method to aid multi-period production capacity planning by quantifying the trade-off between product quality and production cost. The product
Guide to Library Resources for English 110 Finding Books, Periodicals, Microforms and Media
Cakoni, Fioralba
the Library of Congress Classification System. Each book (or bound volume of a periodical) is assigned a call1 Guide to Library Resources for English 110 Finding Books, Periodicals, Microforms and Media held by the University of Delaware Library, you may wish to start by searching DELCAT or WorldCat Local
Operator Non-Availability Periods N. Brauner, G. Finke, V. Lehoux-Lebacque, C. Rapine
Paris-Sud XI, Université de
Operator Non-Availability Periods N. Brauner, G. Finke, V. Lehoux-Lebacque, C. Rapine C. Potts, V. Strusevich July 27, 2007 version-3 Abstract. In scheduling literature, the notion of machine non-availability special periods (the week-ends, holidays, vacations) where the chemists are not available. However, human
Periodic Cooling of Bird Eggs Reduces Embryonic Growth Efficiency Christopher R. Olson*
Vleck, Carol
927 Periodic Cooling of Bird Eggs Reduces Embryonic Growth Efficiency Christopher R. Olson* Carol M, periodic cooling occurs when the in- cubating adult leaves the nest to forage, but the effects of pe- riodic cooling on embryo growth, yolk use, and metabolism are poorly known. To address this question, we
Local energy decay and Strichartz estimates for the wave equation with time-periodic
Petkov, Vesselin
Local energy decay and Strichartz estimates for the wave equation with time-periodic perturbations(z) = (U(T, 0) - z)-1 , (x) C 0 (Rn ), where U(t, s) is the propagator related to the wave equation) and T > 0 is the period. Assuming that R(z) has no poles z with |z| 1, we establish a local energy decay
Evolution of obesity prevalence in France: An Age-Period-Cohort analysis
Evolution of obesity prevalence in France: An Age-Period- Cohort analysis Authors : Ibrahima Diouf1, France. Running title: Age-Period-Cohort analysis for obesity prevalence in France Address in the prevalence of obesity has been reported in France since 1990. We investigated the impact of birth cohort
Mondrik, Nicholas; Marshall, Jennifer L
2015-01-01T23:59:59.000Z
We present a new method of extending the single band Analysis of Variance period estimation algorithm to multiple bands. We use SDSS Stripe 82 RR Lyrae to show that in the case of low number of observations per band and non-simultaneous observations, improvements in period recovery rates of up to $\\approx$60\\% are observed. We also investigate the effect of inter-band observing cadence on period recovery rates. We find that using non-simultaneous observation times between bands is ideal for the multiband method, and using simultaneous multiband data is only marginally better than using single band data. These results will be particularly useful in planning observing cadences for wide-field astronomical imaging surveys such as LSST. They also have the potential to improve the extraction of transient data from surveys with few ($\\lesssim 30$) observations per band across several bands, such as the Dark Energy Survey.
Name:______________ Period:_____________
Lega, Joceline
cup to balance the system again. Fill in the following table for when the system is balanced: Plot on the line and finding the ratio (expressed as a fraction) of the change in the y- coordinates to the change in the x- coordinates. slope= rise run = y2-y1 x2-x1 6: Label two points in the line and fill
Williamson, Jacquelyn
2015-01-01T23:59:59.000Z
The city of Akhenaten I. London: Egypt Exploration Society.of Akhenaten III. London: Egypt Exploration Society. Petrie,the American Research Center in Egypt 25, pp. 117-121. 1991
Klotz, David
2015-01-01T23:59:59.000Z
the Great, Persia invaded Egypt twice and administered it asEl- Qeis) in Upper Egypt (BM 37496; Yoyotte 1972b: pl. 19a;sites are on the fringes of Egypt: Kharga Oasis to the west,
Waszczak, Adam; Ofek, Eran O; Laher, Russ; Masci, Frank; Levitan, David; Surace, Jason; Cheng, Yu-Chi; Ip, Wing-Huen; Kinoshita, Daisuke; Helou, George; Prince, Thomas A; Kulkarni, Shrinivas
2015-01-01T23:59:59.000Z
We fit 54,296 sparsely-sampled asteroid lightcurves in the Palomar Transient Factory to a combined rotation plus phase-function model. Each lightcurve consists of 20+ observations acquired in a single opposition. Using 805 asteroids in our sample that have reference periods in the literature, we find the reliability of our fitted periods is a complicated function of the period, amplitude, apparent magnitude and other attributes. Using the 805-asteroid ground-truth sample, we train an automated classifier to estimate (along with manual inspection) the validity of the remaining 53,000 fitted periods. By this method we find 9,033 of our lightcurves (of 8,300 unique asteroids) have reliable periods. Subsequent consideration of asteroids with multiple lightcurve fits indicate 4% contamination in these reliable periods. For 3,902 lightcurves with sufficient phase-angle coverage and either a reliably-fit period or low amplitude, we examine the distribution of several phase-function parameters, none of which are bimo...
Formation of laser-induced periodic surface structures on niobium by femtosecond laser irradiation
Pan, A.; Dias, A.; Gomez-Aranzadi, M.; Olaizola, S. M. [CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón (Spain); CEIT-IK4 and Tecnun, University of Navarra, Manuel Lardizábal 15, 20018 San Sebastián (Spain); Rodriguez, A. [CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón (Spain)
2014-05-07T23:59:59.000Z
The surface morphology of a Niobium sample, irradiated in air by a femtosecond laser with a wavelength of 800?nm and pulse duration of 100 fs, was examined. The period of the micro/nanostructures, parallel and perpendicularly oriented to the linearly polarized fs-laser beam, was studied by means of 2D Fast Fourier Transform analysis. The observed Laser-Induced Periodic Surface Structures (LIPSS) were classified as Low Spatial Frequency LIPSS (periods about 600?nm) and High Spatial Frequency LIPSS, showing a periodicity around 300?nm, both of them perpendicularly oriented to the polarization of the incident laser wave. Moreover, parallel high spatial frequency LIPSS were observed with periods around 100?nm located at the peripheral areas of the laser fingerprint and overwritten on the perpendicular periodic gratings. The results indicate that this method of micro/nanostructuring allows controlling the Niobium grating period by the number of pulses applied, so the scan speed and not the fluence is the key parameter of control. A discussion on the mechanism of the surface topology evolution was also introduced.
The Lyapunov function for Schrödinger operators with a periodic 2x2 matrix potential
Andrei Badanin; Jochen Brüning; Evgeny Korotyaev
2005-08-29T23:59:59.000Z
We consider the Schr\\"odinger operator on the real line with a 2x2 matrix valued 1-periodic potential. The spectrum of this operator is absolutely continuous and consists of intervals separated by gaps. We define a Lyapunov function which is analytic on a two sheeted Riemann surface. On each sheet, the Lyapunov function has the same properties as in the scalar case, but it has branch points, which we call resonances. We prove the existence of real as well as non-real resonances for specific potentials. We determine the asymptotics of the periodic and anti-periodic spectrum and of the resonances at high energy. We show that there exist two type of gaps: 1) stable gaps, where the endpoints are periodic and anti-periodic eigenvalues, 2) unstable (resonance) gaps, where the endpoints are resonances (i.e., real branch points of the Lyapunov function). We also show that periodic and anti-periodic spectrum together determine the spectrum of the matrix Hill operator.
Microsoft Word - BWCS Scorecard Third period FY 2014 Mar 9 2015...
Office of Environmental Management (EM)
by the material processed fee rate for the period, which happens to be 67Metric Ton. BWCS processed 22,596 MT of DUF 6 . The fee associated with this is 1,513,932. The Total...
Glass, Leon
AND CHAOS IN A PERIODICALLY FORCED OSCILLATOR Rafael PEREZ Instituto de Fisica, Universidad Nacional de Mexico, Mexico City, Mexico and Leon GLASS Department of Physiology, McGill University, 3655 Drummond
Distributed Multi-Period Optimal Power Flow for Demand Response in Microgrids
Yeoh, William
Distributed Multi-Period Optimal Power Flow for Demand Response in Microgrids Paul Scott1 existing passive high-capacity distribution networks. #12;In this new regime, demand response (DR
Roberts, Tony D.
For the first time to our knowledge, continuous nonsegmented channel waveguides in periodically poled KTiOPO4 with guided orthogonal polarizations are used to demonstrate type II background-free second harmonic generation ...
Theoretical and Computational Investigation of Periodically Focused Intense Charged-Particle Beams
Chen, Chiping [Massachusetts Institute of Technology
2013-06-26T23:59:59.000Z
The purpose of this report is to summarize results of theoretical and computational investigations of periodically focused intense charged-particle beams in parameter regimes relevant to the development of advanced high-brightness, high-power accelerators for high-energy physics research. The breakthroughs and highlights in our research in the period from April 1, 2010 to March 30, 2013 were: a) Theory and simulation of adiabatic thermal Child-Langmuir flow; b) Particle-in-cell simulations of adiabatic thermal beams in periodic solenoidal focusing field; c)Dynamics of charged particles in an adiabatic thermal beam equilibrium in a periodic solenoidal focusing field; d) Training of undergraduate researchers and graduate student in accelerator and beam physics. A brief introduction and summary is presented. Detailed descriptions of research results are provided in an appendix of publications at the end of the report.
Skolski, J. Z. P., E-mail: j.z.p.skolski@utwente.nl; Vincenc Obona, J. [Materials innovation institute M2i, Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Römer, G. R. B. E.; Huis in 't Veld, A. J. [Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)
2014-03-14T23:59:59.000Z
A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by “ablation after each laser pulse,” according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to “grow” either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.
Allen, Matthew S.
Identifying parameters of nonlinear structural dynamic systems using linear time- periodic nonlinearity. 1. Introduction Most dynamical systems behave nonlinearly in the most general scenario. This can point bifurcation [1], in rotor dynamic systems with bearing contact nonlinearities [2], in biomechanics
Use and Finance BiAnnual Reporting Form Reporting Period: July 2013 through December 2013
Papalambros, Panos
Use and Finance BiAnnual Reporting Form Reporting Period: July 2013 through December 2013 $ Other (Professional Fees, Telecommunications, Moving) 538,200$ Other (Finance resources services center will be established for finance and human resources transaction processing activities
Effect of availability on multi-period planning of subsea oil and gas production systems
Ruiz Vasquez, Karla Liliana
2009-05-15T23:59:59.000Z
subsea equipment downtime of approximately 7%. As a result, new production planning is accomplished in the effective work period, which will be beneficial in financial risk decisions such as a government’s deliverability contracts....
Wright, Angela Shanna
2004-01-01T23:59:59.000Z
A study was done to investigate and better understand dietary modifications of canine lipid metabolism during gestation, lactation, and the neonatal period. Sexually intact, clinically normal female dogs were bred to the same sire and divided...
Timeline for HWMs and Above-RHWM Elections (2nd Purchase Period...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
31 st of a Rate Case year, for the upcoming Rate Period: 1. Provide updates to forced outage rating, and planned outages. 2. Chooses operating minimum amounts, if applicable....
CO2 Abatement in the UK Power Sector: Evidence from the EU ETS Trial Period
Ellerman, A. Denny
2008-01-01T23:59:59.000Z
This paper provides an empirical assessment of CO2 emissions abatement in the UK power sector during the trial period of the EU ETS. Using an econometrically estimated model of fuel switching, it separates the impacts of ...
Einstein@Home search for periodic gravitational waves in LIGO S4 data
Zucker, Michael E.
A search for periodic gravitational waves, from sources such as isolated rapidly spinning neutron stars, was carried out using 510 h of data from the fourth LIGO science run (S4). The search was for quasimonochromatic waves ...
Einstein@Home search for periodic gravitational waves in early S5 LIGO data
Barsotti, Lisa
This paper reports on an all-sky search for periodic gravitational waves from sources such as deformed isolated rapidly spinning neutron stars. The analysis uses 840 hours of data from 66 days of the fifth LIGO science run ...
Periodicity in Class II methanol masers in high mass star forming regions
Goedhart, S; Gaylard, M J; van der Walt, D J
2013-01-01T23:59:59.000Z
We report the results of 10 years of monitoring of six regularly varying 6.7 GHz methanol masers using the Hartebeesthoek 26m telescope. Observations were done at intervals of 1--2 weeks, with faster sampling during flaring episodes. Four of the sources were also monitored at 12.2 GHz and show correlated variations. We find the Lomb-Scargle periodogram to be the most sensitive method to search for periodicity but possibly prone to false detections. Periods range from 132.8 days (with 26 cycles observed) to 509 days (with 7 cycles observed). Five of the sources show arguably periodic variations, while G331.13-0.24 shows strong periodicity in one peak, with large and variable delays in other peaks.
McLaren, Brian L. (Brian Lloyd), 1958-
2001-01-01T23:59:59.000Z
This dissertation examines the intersection of the modern and the colonial in architecture and culture during the period of Italian colonization of North Africa from 1911 to 1943. Rather than see the colonies as merely a ...
Kaber, David B.
2009-01-01T23:59:59.000Z
Human Factors and Ergonomics in Manufacturing, Vol. 19 (6) 601621 (2009) C 2009 Wiley Periodicals. Correspondence to: David Kaber, The Ergonomics Laboratory, Edward P. Fitts Department of Industrial & Systems
Discrete Self-Similarity Of RR Lyrae Stars II. Period Spectrum For A Very Large Sample
R. L. Oldershaw
2006-06-06T23:59:59.000Z
A recent paper demonstrated a considerable degree of self-similarity between RR Lyrae stars and their atomic scale analogues: excited helium atoms undergoing single-level transition between n = 7 and n = 10. Discrete self-similarity between these fractal analogues was indentified in terms of their masses, radii, oscillation periods, basic morphologies and kinematics. In this second paper on the subject, an extremely large and carefully analyzed sample of RR Lyrae oscillation periods provides further evidence for a unique match between the predicted set of discrete periods, based exclusively on the known helium spectrum and the discrete scaling equations of a fractal cosmological paradigm, and the observed period spectra of RR Lyrae stars.
Enhanced radiation tolerance in nitride multilayered nanofilms with small period-thicknesses
Hong Mengqing; Ren Feng; Zhang Hongxiu; Xiao Xiangheng; Tian Canxin; Fu Dejun; Jiang Changzhong [School of Physics and Technology and Center for Electron Microscopy, Wuhan University, Wuhan 430072 (China); Yang Bing [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Wang Yongqiang [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2012-10-08T23:59:59.000Z
This paper demonstrates a substantial enhancement in radiation tolerance for small period-thickness of CrN/AlTiN multilayered nanofilms. CrN/AlTiN multilayered nanofilms with period-thicknesses of 3, 5, 7, and 9 nm were irradiated by 190 keV Ar{sup +} ions to fluences ranging from 1 to 5 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. Nanofilm with 3 nm period-thickness begins to be amorphized under 5 Multiplication-Sign 10{sup 16} ions/cm{sup 2}, while those with larger period-thicknesses are amorphized under 3 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. Our results show that multilayered ceramic nanofilms are potential radiation tolerant materials with good properties. The interfaces in the multilayered nanofilms act as good sinks to absorb the radiation-induced defects.
Effective slip boundary conditions for arbitrary periodic surfaces: the surface mobility tensor
Kamrin, Kenneth N.
In a variety of applications, most notably microfluidics design, slip-based boundary conditions have been sought to characterize fluid flow over patterned surfaces. We focus on laminar shear flows over surfaces with periodic ...
Exhibition of the periodicity of Quantum Fourier Transformation in Nuclear Magnetic Resonance
Xinhua Peng; Xiwen Zhu; Ximing Fang; Mang Feng; Xiaodong Yang; Maili Liu; Kelin Gao
2002-02-01T23:59:59.000Z
The remarkable capability of quantum Fourier transformation (QFT) to extract the periodicity of a given periodic function has been exhibited by using nuclear magnetic resonance (NMR) techniques. Two separate sets of experiments were performed. In a full QFT, the periodicity were validated with state tomography and fidelity measurements. For a simplified QFT, the three-qubit pseudo-pure state was created by introducting an additional observer spin, and the spectra recorded on the observer spin showed intuitively the power of QFT\\ to find the periodicity. Experimentally realizing the QFT provides a critical step to implement the renowned Shor's quantum factoring algorithm and many other algorithms. Moveover, it can be applied to the study of quantum chaos and other quantum information processing.
Exhibition of the periodicity of Quantum Fourier Transformation in Nuclear Magnetic Resonance
Peng, X; Fang, X; Feng, M; Yang, X; Liu, M; Gao, K; Peng, Xinhua; Zhu, Xiwen; Fang, Ximing; Feng, Mang; Yang, Xiaodong; Liu, Maili; Gao, Kelin
2002-01-01T23:59:59.000Z
The remarkable capability of quantum Fourier transformation (QFT) to extract the periodicity of a given periodic function has been exhibited by using nuclear magnetic resonance (NMR) techniques. Two separate sets of experiments were performed. In a full QFT, the periodicity were validated with state tomography and fidelity measurements. For a simplified QFT, the three-qubit pseudo-pure state was created by introducting an additional observer spin, and the spectra recorded on the observer spin showed intuitively the power of QFT\\ to find the periodicity. Experimentally realizing the QFT provides a critical step to implement the renowned Shor's quantum factoring algorithm and many other algorithms. Moveover, it can be applied to the study of quantum chaos and other quantum information processing.
Brolo, Alexandre G.
;evaluation as chemical sensors and a brief comparison of the pPeriodic Metallic Nanostructures as Plasmonic Chemical Sensors Chiara Valsecchi and Alexandre G generation of low- cost and efficient chemical sensors and biosensors. The extensive variety
Demonstration of sawtooth period control with EC waves in KSTAR plasma
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Jeong, J. H.; Bae, Y. S.; Joung, M.; Kim, D.; Goodman, T. P.; Sauter, O.; Sakamoto, K.; Kajiwara, K.; Oda, Y.; Kwak, J. G.; et al
2015-03-12T23:59:59.000Z
The sawtooth period control in tokamak is important issue in recent years because the sawtooth crash can trigger TM/NTM instabilities and drive plasmas unstable. The control of sawtooth period by the modification of local current profile near the q=1 surface using ECCD has been demonstrated in a number of tokamaks [1, 2] including KSTAR. As a result, developing techniques to control the sawtooth period as a way of controlling the onset of NTM has been an important area of research in recent years [3]. In 2012 KSTAR plasma campaign, the sawtooth period control is carried out by the different depositionmore »position of EC waves across the q=1 surface. The sawtooth period is shortened by on-axis co-ECCD (destabilization), and the stabilization of the sawtooth is also observed by off-axis co-ECCD at outside q=1 surface. In 2013 KSTAR plasma campaign, the sawtooth locking experiment with periodic forcing of 170 GHz EC wave is carried out to control the sawtooth period. The optimal target position which lengthens the sawtooth period is investigated by performing a scan of EC beam deposition position nearby q=1 surface at the toroidal magnetic field of 2.9 T and plasma current of 0.7 MA. The sawtooth locking by the modulated EC beam is successfully demonstrated as in [3-5] with the scan of modulation-frequency and duty-ratio at the low beta (?N~0.5) plasma. In this paper, the sawteeth behavior by the location of EC beam and the preliminary result of the sawtooth locking experiments in KSTAR will be presented.« less
The discrete spectrum of Jacobi matrix related to recurrence relations with periodic coefficients
V. V. Borzov; E. V. Damaskinsky
2015-02-27T23:59:59.000Z
In this note we investigate the discrete spectrum of Jacobi matrix corresponding to polynomials defined by recurrence relations with periodic coefficients. As examples we consider a)the case when period $N$ of coefficients of recurrence relations equals three (as a particular case we consider "parametric" Chebyshev polynomials introduced by authors early); b)the elementary $N$-symmetrical Chebyshev polynomials ($N=3,4,5$), that was introduced by authors in the study of the "composite model of generalized oscillator".
Comparison of quantization of charge transport in periodic and open pumps
Gian Michele Graf; Gregorio Ortelli
2007-09-19T23:59:59.000Z
We compare the charges transported in two systems, a spatially periodic and an open quantum pump, both depending periodically and adiabatically on time. The charge transported in a cycle was computed by Thouless, respectively by Buttiker et al. in the two cases. We show that the results agree in the limit where the two physical situations become the same, i.e., that of a large open pump.
On the spin period distribution in Be/X-ray binaries
Cheng, Z.-Q.; Shao, Y.; Li, X.-D., E-mail: lixd@nju.edu.cn [Department of Astronomy, Nanjing University, Nanjing 210093 (China)
2014-05-10T23:59:59.000Z
There is a remarkable correlation between the spin periods of the accreting neutron stars (NSs) in Be/X-ray binaries (BeXBs) and their orbital periods. Recently, Knigge et al. showed that the distribution of the spin periods contains two distinct subpopulations peaked at ?10 s and ?200 s, respectively, and suggested that they may be related to two types of supernovae for the formation of the NSs, i.e., core-collapse and electron-capture supernovae. Here we propose that the bimodal spin period distribution is likely to be ascribed to different accretion modes of the NSs in BeXBs. When the NS tends to capture material from the warped, outer part of the Be star disk and experiences giant outbursts, a radiatively cooling dominated disk is formed around the NS, which spins up the NS and is responsible for the short-period subpopulation. In BeXBs that are dominated by normal outbursts or are persistent, the accretion flow is advection-dominated or quasi-spherical. The spin-up process is accordingly inefficient, leading to longer periods of the neuron stars. The potential relation between the subpopulations and the supernova mechanism is also discussed.
Dwarf Nova-like Outburst of Short Period Intermediate Polar HT Camelopardalis
Ryoko Ishioka; Taichi Kato; Makoto Uemura; Gary W. Billings; Koichi Morikawa; Ken'ichi Torii; Kenji Tanabe; Arto Oksanen; Harri Hyvonen; Hitoshi Itoh
2002-06-12T23:59:59.000Z
We report the first time-series observations of the short outburst of the proposed intermediate polar HT Cam (=RX J0757.0+6306). On 2001 December 29, we detected the object was undergoing a bright outburst at the magnitude of $m_{vis}=12.2$. Following this detection, we started international joint observations through VSNET. The light curve showed a gradual decline for the first 0.5 d. Following this short plateau phase, the rate of decline dramatically increased to more than 4 mag d$^{-1}$. Within 1.5 d from the outburst detection, the object almost declined to the quiescent level. During the rapidly declining phase, long-term modulations with a period of 86 min and strong pulses with a period of 8.6 min were observed. We concluded that 86 min and 8.6 min are the orbital period and the spin period of HT Cam, respectively. By the detection of the spin period, we confirmed the IP classification of HT Cam. However, its outburst behavior rather resembles that of dwarf novae. The discrepancy between the declining rates of the total flux and the pulse flux strongly suggests that the disk instabilities were taking place during the outburst.
Study of multi-periodic coronal pulsations during an X-class solar flare
Chowdhury, Partha; Dwivedi, B N; Sych, Robert; Moon, Y -J
2015-01-01T23:59:59.000Z
We investigate quasi-periodic coronal pulsations during the decay phase of an X 3.2 class flare on 14 May 2013, using soft X-ray data from the RHESSI satellite. Periodogram analyses of soft X-ray light curves show that 53 s and 72 s periods co-exist in the 3-6, 6-12 and 12-25 KeV energy bands. Considering the typical length of the flaring loop system and observed periodicities, we find that they are associated with multiple (first two harmonics) of fast magnetoacoustic sausage waves. The phase relationship of soft X-ray emissions in different energy bands using cross-correlation technique show that these modes are standing in nature as we do not find the phase lag. Considering the period ratio, we diagnose the local plasma conditions of the flaring region by invoking MHD seismology. The period ratio P1/2P2 is found to be 0.65, which indicates that such oscillations are most likely excited in longitudinal density stratified loops.
Periodic auroral forms and geomagnetic field oscillations in the 1400 MLT region
Potemra, T.A. (Johns Hopkins Univ., Laurel, MD (United States)); Vo, H.; Venkatesan, D.; Cogger, L.L. (Univ. of Calgary, Alberta (Canada)); Erlandson, R.E.; Zanetti, L.J.; Bythrow, P.F.; Anderson, B.J. (Johns Hopkins Univ., Laurel, MD (United States))
1990-05-01T23:59:59.000Z
The UV images obtained with the Viking satellite often show bright features which resemble beads or pearls aligned in the east-west direction between noon and 1800 MLT. Viking acquired a series of 25 UV images during a 28-min period on July 29, 1986, which showed a distinct series of periodic bright features in this region. Magnetic field and hot plasma measurements obtained by Viking confirm that the UV emissions are colocated with the field line projection of an upward-flowing region 1 Birkeland current and precipitating energetic ({approximately}200 eV) electrons. The magnetic field and electric field measurements show transverse oscillations with a nearly constant period of about 3.5 min from 67{degree} invariant latitude equatorward up to the location of the large-scale Birkeland current system near 76{degree} invariant latitude. The electric field oscillations lead the magnetic field oscillations by about a quarter-period. The authors interpret the observed oscillations as standing Alfven waves driven at a frequency near the local resonance frequency by a large-scale wave in the boundary layer. They propose that the energy flux of the precipitating low-energy electrons in this afternoon region is modulated by this boundary wave and produces the periodic UV emission features. The results of this study support the view that large-scale oscillations of magnetospheric boundaries, possibly associated with the Kelvin-Helmholtz instability, can modulate currents, particles, and auroral forms.
Analysis of electromagnetic scattering by nearly periodic structures: an LDRD report.
Johnson, William Arthur; Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Wilton, Donald R. (University of Houston, Houston, TX); Basilio, Lorena I.; Peters, David William; Capolino, F. (University of Houston, Houston, TX)
2006-10-01T23:59:59.000Z
In this LDRD we examine techniques to analyze the electromagnetic scattering from structures that are nearly periodic. Nearly periodic could mean that one of the structure's unit cells is different from all the others--a defect. It could also mean that the structure is truncated, or butted up against another periodic structure to form a seam. Straightforward electromagnetic analysis of these nearly periodic structures requires us to grid the entire structure, which would overwhelm today's computers and the computers in the foreseeable future. In this report we will examine various approximations that allow us to continue to exploit some aspects of the structure's periodicity and thereby reduce the number of unknowns required for analysis. We will use the Green's Function Interpolation with a Fast Fourier Transform (GIFFT) to examine isolated defects both in the form of a source dipole over a meta-material slab and as a rotated dipole in a finite array of dipoles. We will look at the numerically exact solution of a one-dimensional seam. In order to solve a two-dimensional seam, we formulate an efficient way to calculate the Green's function of a 1d array of point sources. We next formulate ways of calculating the far-field due to a seam and due to array truncation based on both array theory and high-frequency asymptotic methods. We compare the high-frequency and GIFFT results. Finally, we use GIFFT to solve a simple, two-dimensional seam problem.
Short-period X-ray oscillations in super-soft novae and persistent SSS
Ness, J -U; Osborne, J P; Kuulkers, E; Henze, M; Piro, A L; Drake, J J; Dobrotka, A; Schwarz, G; Starrfield, S; Kretschmar, P; Hirsch, M; Wilms, J
2015-01-01T23:59:59.000Z
Transient short-period <100s oscillations have been found in the X-ray light curves of three novae during their SSS phase and in one persistent SSS. We pursue an observational approach to determine possible driving mechanisms and relations to fundamental system parameters such as the white dwarf mass. We performed a systematic search for short-period oscillations in all available XMM-Newton and Chandra X-ray light curves of persistent SSS and novae during their SSS phase. To study time evolution, we divided each light curve into short time segments and computed power spectra. We then constructed dynamic power spectra from which we identified transient periodic signals even when only present for a short time. From all time segments of each system, we computed fractions of time when periodic signals were detected. In addition to the previously known systems with short-period oscillations, RS Oph (35s), KT Eri (35s), V339 Del (54s), and Cal 83 (67s), we found one additional system, LMC 2009a (33s), and also c...
Discovery of four periodic methanol masers and updated light curve for a further one
Szymczak, M; Bartkiewicz, A
2015-01-01T23:59:59.000Z
We report the discovery of 6.7 GHz methanol maser periodic flares in four massive star forming regions and the updated light curve for the known periodic source G22.357+0.066. The observations were carried out with the Torun 32 m radio telescope between June 2009 and April 2014. Flux density variations with period of 120 to 245 d were detected for some or all spectral features. A variability pattern with a fast rise and relatively slow fall on time-scale of 30-60 d dominated. A reverse pattern was observed for some features of G22.357+0.066, while sinusoidal-like variations were detected in G25.411+0.105. A weak burst lasting ~520 d with the velocity drift of 0.24 km/s/yr occurred in G22.357+0.066. For three sources for which high resolution maps are available, we found that the features with periodic behaviour are separated by more than 500 au from those without any periodicity. This suggests that the maser flares are not triggered by large-scale homogeneous variations in either the background seed photon fl...
Modification of the Carbon and Beryllium Walls in JET by Erosion, Redeposition and Deuterium Trapping after the 1991 Discharge Period
Broader source: Energy.gov [DOE]
Energy Efficiency Program for Residential Products: Energy Conservation Standards for Residential Dishwashers, Reopening of the Comment Period
MAP3S precipitation chemistry network. Third periodic summary report, July 1978-December 1979
Not Available
1980-05-01T23:59:59.000Z
The MAP3S Precipitation Chemistry Network consists of eight collection sites in the northeastern United States. Precipitation event samples are collected by cooperating site operators, using specially developed sampling equipment. In this, the third periodic summary report, are listed field and concentration data for the period July 1, 1978 to December 31, 1979. Over three years' samples have been collected at most of the sites, which went into operation between September 1976 and October 1978. Samples are chemically analyzed at a central laboratory for 13 pollutant species. Weekly samples in addition to event samples were collected over a 1 1/2 year period at three sites. Analysis of one year's results indicates that there is little difference between the concentrations collected by the two methods in terms of seasonal precipitation-weighted means for all species except dissolved SO/sub 2/. Event samples tend to average about 25% higher in SO/sub 2/ than weekly samples.
Zuo-Bing Wu
2008-03-17T23:59:59.000Z
In this paper, a method to construct topological template in terms of symbolic dynamics for the diamagnetic Kepler problem is proposed. To confirm the topological template, rotation numbers of invariant manifolds around unstable periodic orbits in a phase space are taken as an object of comparison. The rotation numbers are determined from the definition and connected with symbolic sequences encoding the periodic orbits in a reduced Poincar\\'e section. Only symbolic codes with inverse ordering in the forward mapping can contribute to the rotation of invariant manifolds around the periodic orbits. By using symbolic ordering, the reduced Poincar\\'e section is constricted along stable manifolds and a topological template, which preserves the ordering of forward sequences and can be used to extract the rotation numbers, is established. The rotation numbers computed from the topological template are the same as those computed from their original definition.
A study on periodic solutions for the circular restricted three-body problem
Gao, F. B. [School of Mathematical Science, Yangzhou University, Yangzhou 225002 (China); Zhang, W., E-mail: gaofabao@sina.com, E-mail: gaofabao@gmail.com [College of Mechanical Engineering, Beijing University of Technology, Beijing 100124 China (China)
2014-12-01T23:59:59.000Z
For the circular restricted three-body problem (CR3BP) in the inertial frame, we interpret the fact that there is no non-trivial 2?-periodic solution of the problem's homogeneous system. Furthermore, based on Reissig's theory, the existence of periodic solutions for the CR3BP is proved rigorously by using the above fact in conjunction with an a priori estimate. It is significant that the existence of periodic solutions of the CR3BP is mainly influenced by factors such as initial values, primary masses, and selection of the problem's control function. In addition, it is notable that the analytic proof of Poincaré's first class solutions is addressed for all values of the mass parameter in the interval (0, 1), the value of which must be sufficiently small according to previously published literature.
Periods and damping rates of fast sausage oscillations in multi-shelled coronal loops
Chen, Shao-Xia; Xia, Li-Dong; Yu, Hui
2015-01-01T23:59:59.000Z
Standing sausage modes are important in interpreting quasi-periodic pulsations in the lightcurves of solar flares. Their periods and damping times play an important role in seismologically diagnosing key parameters like the magnetic field strength in regions where flare energy is released. Usually such applications are based on theoretical results neglecting unresolved fine structures in magnetized loops. However, the existence of fine structuring is suggested on both theoretical and observational grounds. Adopting the framework of cold magnetohydrodynamics (MHD), we model coronal loops as magnetized cylinders with a transverse equilibrium density profile comprising a monolithic part and a modulation due to fine structuring in the form of concentric shells. The equation governing the transverse velocity perturbation is solved with an initial-value-problem approach, and the effects of fine structuring on the periods $P$ and damping times $\\tau$ of global, leaky, standing sausage modes are examined. A parameter...
Analysis and Control of Period-Doubling Bifurcation in Buck Converters Using Harmonic Balance
Chung-Chieh Fang; Eyad H. Abed
2012-10-27T23:59:59.000Z
Period doubling bifurcation in buck converters is studied by using the harmonic balance method. A simple dynamic model of a buck converter in continuous conduction mode under voltage mode or current mode control is derived. This model consists of the feedback connection of a linear system and a nonlinear one. An exact harmonic balance analysis is used to obtain a necessary and sufficient condition for a period doubling bifurcation to occur. If such a bifurcation occurs, the analysis also provides information on its exact location. Using the condition for bifurcation, a feedforward control is designed to eliminate the period doubling bifurcation. This results in a wider range of allowed source voltage, and also in improved line regulation.
Christopher Beetle; Benjamin Bromley; Richard H. Price
2006-02-08T23:59:59.000Z
The periodic standing wave approach to binary inspiral assumes rigid rotation of gravitational fields and hence helically symmetric solutions. To exploit the symmetry, numerical computations must solve for ``helical scalars,'' fields that are functions only of corotating coordinates, the labels on the helical Killing trajectories. Here we present the formalism for describing linearized general relativity in terms of helical scalars and we present solutions to the mixed partial differential equations of the linearized gravity problem (and to a toy nonlinear problem) using the adapted coordinates and numerical techniques previously developed for scalar periodic standing wave computations. We argue that the formalism developed may suffice for periodic standing wave computations for post-Minkowskian computations and for full general relativity.
Tonn, Bruce Edward [ORNL; Rose, Erin M [ORNL; Schmoyer, Richard L [ORNL; Eisenberg, Joel Fred [ORNL; Ternes, Mark P [ORNL; Schweitzer, Martin [ORNL; Hendrick, Timothy P [ORNL
2012-08-01T23:59:59.000Z
This report describes the third major evaluation of the Program, encompassing program years 2009 to 2011. In this report, this period of time is referred to as the ARRA Period. This is a special period of time for the Program because the American Recovery and Reinvestment Act (ARRA) of 2009 has allocated $5 billion of funding for the Program. In normal program years, WAP s annual appropriation is in the range of $200-250 million, supporting the weatherization of approximately 100,000 homes. With the addition of ARRA funding during these program years, the expectation is that weatherization activity will exceed 300,000 homes per year. In addition to saving energy and reducing low-income energy bills, expanded WAP funding is expected to stimulate the economy by providing new jobs in the weatherization field and allowing low-income households to spend more money on goods and services by spending less on energy.
Chemical Technology Division progress report for the period April 1, 1985 to December 31, 1986
Not Available
1987-08-01T23:59:59.000Z
This progress report summarizes the research and development efforts conducted in the Chemical Technology Division (Chem Tech) during the period April 1, 1985, through December 31, 1986. The following major areas are covered in the discussion: nuclear and chemical waste management, environmental control technology, basic science and technology, biotechnology research, transuranium-element processing, Nuclear Regulatory Commission programs, radioactive materials production, computer/engineering applications, fission energy, environmental cleanup projects, and various other work activities. As an appendix, the Administrative Summary presents a comprehensive compilation of publications, oral presentations, awards and recognitions, and patents of Chem Tech staff members during this report period. An organization chart, a staffing level and financial summary, and lists of seminars and Chem Tech consultants for the period are also included to provide additional information. 78 figs., 40 tabs.
Oscar P. Bruno; Stephen P. Shipman; Catalin Turc; Stephanos Venakides
2013-07-04T23:59:59.000Z
We present efficient methods for computing wave scattering by diffraction gratings that exhibit two-dimensional periodicity in three dimensional (3D) space. Applications include scattering in acoustics, electromagnetics and elasticity. Our approach uses boundary-integral equations. The quasi-periodic Green function is a doubly infinite sum of scaled 3D free-space outgoing Helmholtz Green functions. Their source points are located at the nodes of a periodicity lattice of the grating. For efficient numerical computation of the lattice sum, we employ a smooth truncation. Super-algebraic convergence to the Green function is achieved as the truncation radius increases, except at frequency-wavenumber pairs at which a Rayleigh wave is at exactly grazing incidence to the grating. At these "Wood frequencies", the term in the Fourier series representation of the Green function that corresponds to the grazing Rayleigh wave acquires an infinite coefficient and the lattice sum blows up. At Wood frequencies, we modify the Green function by adding two types of terms to it. The first type adds weighted spatial shifts of the Green function to itself with singularities below the grating; this yields algebraic convergence. The second-type terms are quasi-periodic plane wave solutions of the Helmholtz equation. They reinstate (with controlled coefficients) the grazing modes, effectively eliminated by the terms of first type. These modes are needed in the Green function for guaranteeing the well-posedness of the boundary-integral equation that yields the scattered field. We apply this approach to acoustic scattering by a doubly periodic 2D grating near and at Wood frequencies and scattering by a doubly periodic array of scatterers away from Wood frequencies.
Pump-probe imaging of laser-induced periodic surface structures after ultrafast irradiation of Si
Murphy, Ryan D. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)
2013-09-30T23:59:59.000Z
Ultrafast pump-probe microscopy has been used to investigate laser-induced periodic surface structure (LIPSS) formation on polished Si surfaces. A crater forms on the surface after irradiation by a 150 fs laser pulse, and a second, subsequent pulse forms LIPSS within the crater. Sequentially delayed images show that LIPSS with a periodicity slightly less than the fundamental laser wavelength of 780 nm appear on Si surfaces ?50 ps after arrival of the second pump laser pulse, well after the onset of melting. LIPSS are observed on the same timescale as material removal, suggesting that their formation involves material ejection.
Oceanography of Accreting Neutron Stars: Non-Radial Oscillations and Periodic X-Ray Variability
Lars Bildsten; Andrew Cumming; Greg Ushomirsky; Curt Cutler
1997-12-31T23:59:59.000Z
Observations of quasi-periodic oscillations (QPOs) in the luminosity from many accreting neutron stars (NS) have led us to investigate a source of periodicity prevalent in other stars: non-radial oscillations. After summarizing the structure of the atmosphere and ocean of an accreting NS, we discuss the various low l g-modes with frequencies in the 1-100 Hz range. Successful identification of a non-radial mode with an observed frequency would yield new information about the thermal and compositional makeup of the NS, as well as its radius. We close by discussing how rapid rotation changes the g-mode frequencies.
Los Alamos National Laboratory's Chemistry Division Presents Periodic Table of the Elements
Hochberg, Michael
144.2 61 Pm (147) 62 Sm 150.4 63 Eu 152.0 64 Gd 157.3 65 Tb 158.9 66 Dy 162.5 67 Ho 164.9 68 Er 167.lanl.gov/periodic/ (1 of 3) [5/17/2001 4:06:20 PM] #12;Lanthanide Series* 58 Ce 140.1 59 Pr 140.9 60 Nd) [5/17/2001 4:06:20 PM] #12;about this resource A Periodic Table of the Elements at Los Alamos
Shi, Xuesong; Jiang, Lan; Li, Xin, E-mail: lixin02@bit.edu.cn; Zhang, Kaihu; Yu, Dong; Yu, Yanwu [NanoManufacturing Fundamental Research Joint Laboratory of National Science Foundation of China, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081 (China); Lu, Yongfeng [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511 (United States)
2014-07-21T23:59:59.000Z
The dependence of periodic structures and ablated areas on temporal pulse shaping is studied upon irradiation of fused silica by femtosecond laser triple-pulse trains. Three types of periodic structures can be obtained by using pulse trains with designed pulse delays, in which the three-dimensional nanopillar arrays with ?100–150?nm diameters and ?200?nm heights are first fabricated in one step. These nanopillars arise from the break of the ridges of ripples in the upper portion, which is caused by the split of orthogonal ripples in the bottom part. The localized transient electron dynamics and corresponding material properties are considered for the morphological observations.
Joseph M. Starobin; Vivek Varadarajan
2011-06-02T23:59:59.000Z
We analyze the effects of spatially extended periodic forcing on the dynamics of one-dimensional excitation waves. Entrainment of unstable primary waves has been studied numerically for different amplitudes and frequencies of additional sub-threshold stimuli. We determined entrainment regimes under which excitation blocks were transformed into consistent 1:1 responses. These responses were spatially homogeneous and synchronized in the entire excitable medium. Compared to primary pulses, pulses entrained by secondary stimulations were stable at considerably shorter periods which decreased at higher amplitudes and greater number of secondary stimuli. Our results suggest a practical methodology for stabilization of excitation in reaction-diffusion media with regions of reduced excitability.
Limit Distribution of Averages over Unstable Periodic Orbits Forming Chaotic Attractor
Denis S. Goldobin
2012-08-08T23:59:59.000Z
We address the question of representativeness of a single long unstable periodic orbit for properties of the chaotic attractor it is embedded in. Y. Saiki and M. Yamada [Phys. Rev. E 79, 015201(R) (2009)] have recently suggested the hypothesis that there exist a limit distribution of averages over unstable periodic orbits with given number of loops, N, which is not a Dirac delta-function for infinitely long orbits. In this paper we show that the limit distribution is actually a delta-function and standard deviations decay as 1/sqrt(N) for large enough N.
Periodic striations on beryllium and tungsten surfaces by indirect femtosecond laser irradiation
Lungu, C. P.; Tico?, C. M., E-mail: catalin.ticos@inflpr.ro; Poro?nicu, C.; Jepu, I.; Lungu, M.; Marcu, A.; Luculescu, C.; Cojocaru, G.; Ursescu, D.; B?nici, R.; Ungureanu, G. R. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania)] [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania)
2014-03-10T23:59:59.000Z
Femtosecond laser pulses with ??=?800?nm were focused in air at one atmosphere and in deuterium (D) at low pressure. Submicron periodic structures were observed on surfaces made of Be, W and a mixture of Be-W immersed in these gases and placed nearly parallel with the laser beam, at 300??m from the focal spot. In air, no structures were observed on Be. For the Be-W mixture, the periodic structures were uniform and parallel when formed in D but irregular in air. In this last case the striations were organized into small patches of 1 to 2 ?m in size.
Short period fluctuations of sea level in the West Florida Keys
Hsu, Sangem
1978-01-01T23:59:59.000Z
stages at each station. It is found that seiches at Vaca Key show strong correlations with weather conditions and also that short period fluctuations at several stations are influenced by effects of non-linear residual tidal currents (effects through... Fluctuations of Sea Level at Stations with Data Recorded in April. 4. 3 Short Period Fluctuations of Sea Level at Stations with Data Recorded in June. 21 21 24 vi 4. 4 Residual Tidal Currents 4. 5 Seiches in Vaca Key 4. 6 The Effects of Friction...
QUASI-PERIODICITIES OF THE BL LACERTAE OBJECT PKS 2155–304
Sandrinelli, A.; Treves, A. [Università degli Studi dell' Insubria, Via Valleggio 11, I-22100 Como (Italy); Covino, S., E-mail: asandrinelli@yahoo.it [INAF-Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, I-23807 Merate (Italy)
2014-09-20T23:59:59.000Z
We have searched for periodicities in our VRIJHK photometry of PKS 2155–304, which covers the years 2005-2012. A peak of the Fourier spectrum with high significance is found at T ? 315 days, confirming the recent findings by Zhang et al. The examination of the gamma-ray light curves from the Fermi archives yields a significant signal at ?2T, which, while nominally significant, involves data spanning only ?6T. Assuming a black hole mass of 10{sup 9} M {sub ?}, the Keplerian distance corresponding to the quasi-period T is ?10{sup 16} cm, about 50 Schwarzschild radii.
Boyd, Douglas Kevin
1986-01-01T23:59:59.000Z
PARAJE (DE FRA CRISTOBAL): INVESTIGATIONS OF A TERRITORIAL PERIOD HISPANIC VILLAGE SITE IN SOUTHERN NEW MEXICO A Thesis by DOUGLAS KE V I N BOYD Submitted to the Graduate College of Texas A8iM University in partial fulfillment... of the requirements for the degree of MASTER OF ARTS May 1986 Major Subj ect: Ant hropol ogy PARAJE (DE FRA CRISTOBAL): INVESTIGATIONS OF A TERRITORIAL PERIOD HISPANIC VILLAGE SITE IN SOUTHERN NEW MEXICO A Thesis by DOUGLAS KEVIN BOYD Approved as to style...
The quasi-periodic nature of wall slip for molten plastics in large amplitude oscillatory shear
Adrian, David Warren
1992-01-01T23:59:59.000Z
is not to be confused with a quasi-periodic spectrum like Figure 15 because of its strong continuous component. 0. 01 X 0. 001 0. 0001 0. 2 0. 4 0. 6 f (Hz) Figure 14. Chaotic amplitude spectrum of Duffing's equation. 0. 1 0. 01 X 0. 001 0. 0001 1E-05 0... amplitude spectrum for a viscoelastic melt in LAOS 6. Pipkin diagram, adapted from Dealy and Wissbrun (1990), 14 showing the regimes of oscillatory shear for a viscoelastic melt . . . . 15 7. Time domain plot of the quasi-periodic forced van der Pol...
Analysis of periodically-forced turbulence in the rapid distortion limit
O'Neil, Joshua Robert
2006-04-12T23:59:59.000Z
ANALYSIS OF PERIODICALLY-FORCED HOMOGENEOUS TURBULENCE IN THE RAPID DISTORTION LIMIT A Thesis by JOSHUA R. O?NEIL Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE December 2004 Major Subject: Aerospace Engineering ANALYSIS OF PERIODICALLY-FORCED HOMOGENEOUS TURBULENCE IN THE RAPID DISTORTION LIMIT A Thesis by JOSHUA R. O?NEIL Submitted to Texas A&M University in partial fulfillment of the requirements...
Complete Chaotic Mixing in an Electro-osmotic Flow by Destabilization of Key Periodic Pathlines
R. Chabreyrie; C. Chandre; P. Singh; N. Aubry
2011-02-07T23:59:59.000Z
The ability to generate complete, or almost complete, chaotic mixing is of great interest in numerous applications, particularly for microfluidics. For this purpose, we propose a strategy that allows us to quickly target the parameter values at which complete mixing occurs. The technique is applied to a time periodic, two-dimensional electro-osmotic flow with spatially and temporally varying Helmoltz-Smoluchowski slip boundary conditions. The strategy consists of following the linear stability of some key periodic pathlines in parameter space (i.e., amplitude and frequency of the forcing), particularly through the bifurcation points at which such pathlines become unstable.
Quantization and 2{pi} periodicity of the axion action in topological insulators
Vazifeh, M. M.; Franz, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, V6T 1Z1 (Canada)
2010-12-15T23:59:59.000Z
The Lagrangian describing the bulk electromagnetic response of a three-dimensional strong topological insulator contains a topological ''axion'' term of the form {theta}E{center_dot}B. It is often stated (without proof) that the corresponding action is quantized on periodic space time and therefore invariant under {theta}{yields}{theta}+2{pi}. Here we provide a simple, physically motivated proof of the axion action quantization on the periodic space time, assuming only that the vector potential is consistent with single valuedness of the electron wave functions in the underlying insulator.
The quasi-periodic nature of wall slip for molten plastics in large amplitude oscillatory shear
Adrian, David Warren
1992-01-01T23:59:59.000Z
is not to be confused with a quasi-periodic spectrum like Figure 15 because of its strong continuous component. 0. 01 X 0. 001 0. 0001 0. 2 0. 4 0. 6 f (Hz) Figure 14. Chaotic amplitude spectrum of Duffing's equation. 0. 1 0. 01 X 0. 001 0. 0001 1E-05 0... amplitude spectrum for a viscoelastic melt in LAOS 6. Pipkin diagram, adapted from Dealy and Wissbrun (1990), 14 showing the regimes of oscillatory shear for a viscoelastic melt . . . . 15 7. Time domain plot of the quasi-periodic forced van der Pol...
Small angle neutron scattering on periodically deformed polymers A. R. Rennie
Boyer, Edmond
765 Small angle neutron scattering on periodically deformed polymers A. R. Rennie Institut für Phys-768 SEPTEMBRE 1984, 1. Introduction. Neutron scattering has proved a useful tool for the investigation of a wide time for a small angle neutron scattering spectrum is several minutes. Obser- vation on rapidly
Barua, Rajeev
, and chemical content to enable precise application of agents such as water, fertilizer, and pesticideContention-Free Periodic Message Scheduler Medium Access Control in Wireless Sensor / Actuator implemented with a contention-free message scheduler. A message scheduler is used to determine which message
Tunable optical fiber devices based on broadband long-period gratings and pumped microfluidics
Rogers, John A.
Tunable optical fiber devices based on broadband long-period gratings and pumped microfluidics; accepted 8 October 2003 This letter describes classes of tunable microfluidic fiber FF devices that use spectral range. Dynamic tuning is achieved by electrowetting-based pumping of microfluidic plugs back
Subsidence in the Michigan basin produced ~5 km of sedimentation over a period of more
ABSTRACT Subsidence in the Michigan basin produced ~5 km of sedimentation over a period of more a plate tectonic framework for the his- tory of the Michigan basin. INTRODUCTION The Michigan basin of the Michigan basin has led to numerous proposals for basin subsidence mechanisms, including thermal contraction
Solid State Division progress report for period ending March 31, 1992
Green, P.H.; Hinton, L.W. [eds.
1992-09-01T23:59:59.000Z
During this period, the division conducted a broad, interdisciplinary materials research program with emphasis on theoretical solid state physics, superconductivity, neutron scattering, synthesis and characterization of materials, ion beam and laser processing, and the structure of solids and surfaces. The High Flux Isotope Reactor was returned to full operation.
Multi-period Optimal Procurement and Demand Responses in the Presence of Uncertain Supply
Low, Steven H.
Multi-period Optimal Procurement and Demand Responses in the Presence of Uncertain Supply Libin markets, uncertainty in renewable generation, and real-time dynamic demand response. A load-serving entity day-ahead decision, propose real-time demand response algorithm, and study the effect of volume
Periodic Flux Variability of Stars due to the Reflex Doppler Effect Induced by Planetary Companions
Abraham Loeb; B. Scott Gaudi
2003-03-28T23:59:59.000Z
Upcoming space-based photometric satellites offer the possibility of detecting continuum flux variability at the micro-magnitude level. We show that the Doppler flux variability induced by the reflex motion of stars due to planetary companions has an amplitude of (3-alpha)K/c, where K is the reflex radial velocity amplitude and alpha is the logarithmic slope of source spectral flux in the observed frequency band. For many of the known close-in planetary systems with periods less than ~0.2 years, the periodic Doppler variability is of order a micromagnitude, and is significant relative to the variability caused by reflected light from the planetary companion. For companions with periods greater than ~0.2 years, the Doppler signal is larger than the reflected light signal. We show that the future photometric satellites should reach the sensitivity to detect this Doppler variability. In particular, the Kepler satellite should have the photon-noise sensitivity to detect at a signal-to-noise ratio > 5, all planets with minimum mass greater than 5 Jupiter masses, and periods less than 0.1 years around the 10,000 main-sequence stars with spectral types A through K and apparent magnitude V<12 in its field-of-view.
Modeling Red Blood Cell and Iron Dynamics in Patients Undergoing Periodic EPO and Iron Treatments
Modeling Red Blood Cell and Iron Dynamics in Patients Undergoing Periodic EPO and Iron Treatments H in the kidneys, that stimulates red blood cell (RBC) production. Without intervention, patients suffer from, erythrocyte, red blood cell, chronic kidney disease, dialysis, iron, neocytolysis, hepcidin, EPO, hemoglobin e
Global Clock, Physical Time Order and Pending Period Analysis in Multiprocessor Systems
Chen, Yunji; Hu, Weiwu
2009-01-01T23:59:59.000Z
In multiprocessor systems, various problems are treated with Lamport's logical clock and the resultant logical time orders between operations. However, one often needs to face the high complexities caused by the lack of logical time order information in practice. In this paper, we utilize the \\emph{global clock} to infuse the so-called \\emph{pending period} to each operation in a multiprocessor system, where the pending period is a time interval that contains the performed time of the operation. Further, we define the \\emph{physical time order} for any two operations with disjoint pending periods. The physical time order is obeyed by any real execution in multiprocessor systems due to that it is part of the truly happened operation orders restricted by global clock, and it is then proven to be independent and consistent with traditional logical time orders. The above novel yet fundamental concepts enables new effective approaches for analyzing multiprocessor systems, which are named \\emph{pending period analy...
Real-time Scheduling of periodic tasks in a monoprocessor system with rechargeable energy storage
Paris-Sud XI, Université de
Real-time Scheduling of periodic tasks in a monoprocessor system with rechargeable energy storage-time computing system that is powered through a renewable energy storage device. In this context, two constraints for the properties of the energy source, capacity of the energy storage as well as energy consumption of the tasks
Final report on Project ESEPP (LEAP+) for the period January 1, 1996 - August 1, 1998
Henley, Vernard Jr.
2000-03-10T23:59:59.000Z
This is the final report for the Project to Enhance Student Science and Engineering Preparation at the Pre-College Level (Project ESEPP) for the period from January 1, 1996 through August 1, 1998. This report summarizes the accomplishments of the program and its ability to meet the objectives described in the original proposal (1990).
Spatial periodicity in growth plate shear mechanical properties is disrupted by vitamin D deficiency
Cohen, Itai
Spatial periodicity in growth plate shear mechanical properties is disrupted by vitamin D modulus Vitamin D a b s t r a c t The growth plate is a highly organized section of cartilage in the long disruption caused by a dietary deficiency of vitamin D. The shear mechanical properties of the proximal
Testing eccentricity pumping mechanisms to model eccentric long period sdB binaries with MESA
Vos, Joris; Marchant, Pablo; Van Winckel, Hans
2015-01-01T23:59:59.000Z
Hot subdwarf-B stars in long-period binaries are found to be on eccentric orbits, even though current binary-evolution theory predicts those objects to be circularised before the onset of Roche-lobe overflow (RLOF). We aim to find binary-evolution mechanisms that can explain these eccentric long-period orbits, and reproduce the currently observed period-eccentricity diagram. Three different processes are considered; tidally-enhanced wind mass-loss, phase-dependent RLOF on eccentric orbits and the interaction between a circumbinary disk and the binary. The binary module of the stellar-evolution code MESA (Modules for Experiments in Stellar Astrophysics) is extended to include the eccentricity-pumping processes. The effects of different input parameters on the final period and eccentricity of a binary-evolution model are tested with MESA. The end products of models with only tidally-enhanced wind mass-loss can indeed be eccentric, but these models need to lose too much mass, and invariably end up with a helium ...
Broader source: Energy.gov [DOE]
This report provides the results of a review conducted by the Office of Nuclear Safety (AU-30) of the implementation of periodic Natural Phenomena Hazards (NPH) assessment reviews by sites reporting to the National Nuclear Security Administration (NNSA), and the Offices of Environmental Management, Nuclear Energy, and Science.
Modeling the Coastal Ocean over a Time Period of Several April 8, 2008
Frénod, Emmanuel
, lost objects or oil spill over long periods of time in near coastal ocean areas. Such methods would. The final target of this program is to develop methods to forecast the drift of things like con- tainers be of interest for services in charge of maritime safety, environmental studies or pollution impact assessment
X-ray periodicities in sources observed by the RXTE ASM
Shivamoggi, Vasudha B
2005-01-01T23:59:59.000Z
The X-ray intensities measured from 230 X-ray sources observed by the RXTE All-Sky Monitor (ASM) were analyzed for periodic behavior. The ASM has been observing sources for nine years in the 1.5-12 keV energy range. In ...
Quarterly RCRA Groundwater Monitoring Data for the Period April Through June 2006
Hartman, Mary J.
2006-11-01T23:59:59.000Z
This report provides information about RCRA groundwater monitoring for the period April through June 2006. Seventeen RCRA sites were sampled during the reporting quarter. Sampled sites include seven monitored under groundwater indicator evaluation (''detection'') programs, eight monitored under groundwater quality assessment programs, and two monitored under final-status programs.
Math 421, Fourier Analysis Suppose we sample a periodically varying quantity such as an intensity or
Offin, Dan
Math 421, Fourier Analysis Suppose we sample a periodically varying quantity such as an intensity tone 200 400 600 800 100012001400 5 10 15 20 25 The Fourier analysis of the tone Which button was pressed? A general method was found by Jean Baptiste Joseph Fourier (1768 - 1830) in 1807. His method
Kuladeep, Rajamudili; Dar, Mudasir H.; Rao, D. Narayana, E-mail: dnrsp@uohyd.ac.in, E-mail: dnr-laserlab@yahoo.com [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Deepak, K. L. N. [Department of Physics and Center for Research in Photonics, University of Ottawa, 150 Louis Pasteur, Ottawa K1N6N5, Ontario (Canada)
2014-09-21T23:59:59.000Z
In this communication, we demonstrate the generation of laser-induced periodic sub-wavelength surface structures (LIPSS) or ripples on a bulk aluminum (Al) and Al nanoparticles (NPs) by femtosecond (fs) laser direct writing technique. Laser irradiation was performed on Al surface at normal incidence in air and by immersing in ethanol (C?H?OH) and water (H?O) using linearly polarized Ti:sapphire fs laser pulses of ~110 fs pulse duration and ~800 nm wavelength. Field emission scanning electron microscope is utilized for imaging surface morphology of laser written structures and it reveals that the spatial periodicity as well as the surface morphology of the LIPSS depends on the surrounding dielectric medium and also on the various laser irradiation parameters. The observed LIPSS have been classified as low spatial frequency LIPSS which are perpendicularly oriented to the laser polarization with a periodicity from 460 to 620 nm and high spatial frequency LIPSS which spectacles a periodicity less than 100 nm with the orientation parallel to the polarization of the incident laser beam. Fabricated colloidal solutions, which contain the Al NPs, were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). TEM results reveal the formation of internal cavities in Al NPs both in ethanol and water. Formation mechanism of LIPSS and cavities inside the nanoparticles are discussed in detail.
Autophagic response of higher plant cells to a prolonged period of sucrose deprivation
Paris-Sud XI, Université de
, sudden temperature drop, water stress or the decrease of the circadian light period diminishes the rates in 3! P nuclear magnetic resonance (NMR) experi- ments. Cells harvested from the culture medium were acid (PCA) extraction (Roby et aL, 1987), sucrose and starch determi- nations (Journet et al., 1986
THE INCREASING ROTATION PERIOD OF COMET 10P/TEMPEL 2
Knight, Matthew M.; Schleicher, David G. [Lowell Observatory, 1400 W. Mars Hill Rd, Flagstaff, AZ 86001 (United States); Farnham, Tony L. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Schwieterman, Edward W., E-mail: knight@lowell.ed [Physics and Space Sciences, Florida Institute of Technology, 150 W. University Blvd., Melbourne, FL 32901 (United States)
2011-01-15T23:59:59.000Z
We imaged comet 10P/Tempel 2 on 32 nights from 1999 April through 2000 March. R-band light curves were obtained on 11 of these nights from 1999 April through 1999 June, prior to both the onset of significant coma activity and perihelion. Phasing of the data yields a double-peaked light curve and indicates a nucleus rotational period of 8.941 {+-} 0.002 hr with a peak-to-peak amplitude of {approx}0.75 mag. Our data are sufficient to rule out all other possible double-peaked solutions as well as the single- and triple-peaked solutions. This rotation period agrees with one of five possible solutions found in post-perihelion data from 1994 by Mueller and Ferrin (Icarus, 123, 463-477) and unambiguously eliminates their remaining four solutions. We applied our same techniques to published light curves from 1988 which were obtained at an equivalent orbital position and viewing geometry as in 1999. We found a rotation period of 8.932 {+-} 0.001 hr in 1988, consistent with the findings of previous authors and incompatible with our 1999 solution. This reveals that Tempel 2 spun-down by {approx}32 s between 1988 and 1999 (two intervening perihelion passages). If the spin-down is due to a systematic torque, then the rotation period prior to perihelion during the 2010 apparition is expected to be an additional 32 s longer than in 1999.
Linares, M.
We present a comprehensive study of the thermonuclear bursts and millihertz quasi-periodic oscillations (mHz QPOs) from the neutron star (NS) transient and 11 Hz X-ray pulsar IGR J17480–2446, located in the globular cluster ...
A Periodic Portfolio Scheduler for Scientific Computing in the Data Center
Feitelson, Dror
A Periodic Portfolio Scheduler for Scientific Computing in the Data Center Kefeng Deng1,2 , Ruben.S.Verboon@student.tudelft.nl, A.Iosup@tudelft.nl Abstract. The popularity of data centers in scientific computing has led to new of efficient scheduling algorithms for the data center is an increasingly costlier and more difficult challenge
Boyer, Edmond
Generation of polarization-entangled photons using type-II doubly periodically poled lithium the issue of the generation of non-degenerate cross-polarization-entangled photon pairs using type-conversion processes, namely ordinary pump photon down- conversion to either extraordinary signal and ordinary idler
Weekly Security Incident Log Period of Aug 12 -Aug 18, 2013
2013-001248 THOMPSON ROAD Gas leak Security , Toronto Fire, Toronto Police, and Occupational Health and Safety responded to a report of a natural gas leak in the area of the Life Science BuildingWeekly Security Incident Log Period of Aug 12 - Aug 18, 2013 Incident No. Reported Date Building
Weekly Security Incident Log Period of Feb 6 -Feb 12, 2012
Gas leak Security and Toronto Fire responded to a report of a natural gas odour in B-wing. TorontoWeekly Security Incident Log Period of Feb 6 - Feb 12, 2012 Incident No. Reported Date Building\\Const. Security, York Fire Prevention and Toronto Fire responded to a fire alarm. The cause of the alarm
Weekly Security Incident Log Period of Jul 9 -Jul 15, 2012
and Safety responded to a report of a natural gas odour in the building. The building was checked and no natural gas was found. Toronto Fire determined that all was in order. 7/12/2012 07:31 AM HazardousWeekly Security Incident Log Period of Jul 9 - Jul 15, 2012 Incident No. Reported Date Building
Weekly Security Incident Log Period of Apr 29 -May 5, 2013
2013-000845 YORK LANES RETAIL Gas leak Security, Toronto Fire and Enbridge Gas responded to a report of a natural gas odour in the building. The source of the odour was located in a restaurant kitchen. EnbridgeWeekly Security Incident Log Period of Apr 29 - May 5, 2013 Incident No. Reported Date Building
Copyright 2009 by ASME Laminar fully developed flow in streamwise-periodic
Bahrami, Majid
. Rough tubes or channels with ribs on their surfaces are examples of streamwise-periodic ducts which for straight channels of arbitrary cross-section, compact models are developed for linear and sinusoidal wall) very tall channels and compared with the available experimental and numerical data in the literature
POSSIBLE DISINTEGRATING SHORT-PERIOD SUPER-MERCURY ORBITING KIC 12557548
Chiang, E.
We report on the discovery of stellar occultations, observed with Kepler, which recur periodically at 15.685 hr intervals, but which vary in depth from a maximum of 1.3% to a minimum that can be less than 0.2%. The star ...
Summary: An Approximately 1.3-Year Periodicity in ap and IMP 8 Solar Wind Observations
Richardson, John
of geomagnetic activity, the ap index (a measure of p geomagnetic disturbance) is examined to look peak [Paularena et al., 1995]. This agreement t in long-period behavior between a geomagnetic index NASA contract 959203 from JPL to MIT a N (Voyager). One of the authors (AS) currently holds ational
A biped static balance control and torque pattern learning under unknown periodic external forces
Ito, Satoshi
A biped static balance control and torque pattern learning under unknown periodic external forces balancing task in which an unknown external force is exerted, using so-called `ankle strategy' model. When an external force is pe- riodic, a human adaptively maintains the balance, next learns how much force should
Lynch-Stieglitz, Jean
as freely meandering jet in the open ocean. On a basin- wide scale, the Gulf Stream separation latitudePersistence of Gulf Stream separation during the Last Glacial Period: Implications for current at which the Gulf Stream separated from the western boundary of the Atlantic Ocean in the past. The modern
Spectral theory for a class of periodically perturbed unbounded Jacobi matrices: elementary methods
Spectral theory for a class of periodically perturbed unbounded Jacobi matrices: elementary methods of his 80th birthday Abstract We use elementary methods to give a full characterization of the spectral properties of unbounded Jacobi matrices with zero diagonal and o#Âdiagonal entries of the type # n = n # + c
STRESS-INDUCED PERIODIC FRACTURE PATTERNS IN THIN FILMS Alex A. Volinsky1
Volinsky, Alex A.
STRESS-INDUCED PERIODIC FRACTURE PATTERNS IN THIN FILMS Alex A. Volinsky1 , Neville R. Moody2 applied stresses in thin films can cause film fracture. In the case of compressive stress thin film is the key for causing thin film fracture, either in tension, or compression, although the influence
Einstein@Home all-sky search for periodic gravitational waves in LIGO S5 data
Barsotti, Lisa
This paper presents results of an all-sky search for periodic gravitational waves in the frequency range [50,1?190]??Hz and with frequency derivative range of ?[-20,1.1]×10[superscript -10]??Hz?s[superscript -1] for the ...
Investigation of long-period fiber gratings induced by high-intensity femtosecond UV laser pulses
Nikogosyan, David N.
efficiency with that for other existing meth- ods of recording. We studied the temperature sensing properties changes in the fiber core induced by thermal heating, were developed. They include the use of a CO2 laserInvestigation of long-period fiber gratings induced by high-intensity femtosecond UV laser pulses
SINE WAVE CANCELATION THROUGH A PERIODIC TRANSFER FUNCTION Pierre Granjon, Christine Servire
Paris-Sud XI, Université de
. Moreover, the transfer function of this process can be shown periodic, and therefore time-varying. Thus we, a stator coil is supplied with a current i(t). It generates an additional vibration signal v(t), which the error e(t). It is measured with an accelerometer on the stator frame. i(t) m(t) d(t) v
LARGE TORSIONAL OSCILLATIONS IN A SUSPENSION BRIDGE: MULTIPLE PERIODIC SOLUTIONS TO A NONLINEAR
Moore, Kristen
of the Tacoma Narrows Bridge, we solve the damped equation numerically and observe that multiple periodic the dramatic and finally destructive torsional oscillations of the Tacoma Narrows Bridge that preceded its observed on the Tacoma Narrows and other suspension bridges. Theoretical and numerical evidence to support
Periodic Broadcast with Dynamic Server Selection Ewa Kusmierek, Yingping Lu and David H.C. Du
Minnesota, University of
1 Periodic Broadcast with Dynamic Server Selection Ewa Kusmierek, Yingping Lu and David H.C. Du requirements and resource availability problem. Dynamic service selection enables clients to choose a server offering the best performance. Proper server selection is especially important for video streaming over
Modeling Alveolar Volume Changes During Periodic Breathing in Heterogeneously Ventilated Lungs
Jeavons, Peter
Modeling Alveolar Volume Changes During Periodic Breathing in Heterogeneously Ventilated Lungs SARA-uniform breathing pattern for a lung with an inhomogeneous gas distribution, such as that observed in some subjects of irregular breathing caused by small, poorly ventilated regions of the lung. Presented here is an extension
Lithographically induced self-assembly of periodic polymer micropillar Stephen Y. Choua)
importance to science and technology. Technologi- cally, self-assembly promises not only low cost and highLithographically induced self-assembly of periodic polymer micropillar arrays Stephen Y. Choua by placing a second plate called a mask a distance above the polymer film. The pillars, formed by rising
Periodic equivalence ratio modulation method and apparatus for controlling combustion instability
Richards, George A. (Morgantown, WV); Janus, Michael C. (Baltimore, MD); Griffith, Richard A. (Morgantown, WV)
2000-01-01T23:59:59.000Z
The periodic equivalence ratio modulation (PERM) method and apparatus significantly reduces and/or eliminates unstable conditions within a combustion chamber. The method involves modulating the equivalence ratio for the combustion device, such that the combustion device periodically operates outside of an identified unstable oscillation region. The equivalence ratio is modulated between preselected reference points, according to the shape of the oscillation region and operating parameters of the system. Preferably, the equivalence ratio is modulated from a first stable condition to a second stable condition, and, alternatively, the equivalence ratio is modulated from a stable condition to an unstable condition. The method is further applicable to multi-nozzle combustor designs, whereby individual nozzles are alternately modulated from stable to unstable conditions. Periodic equivalence ratio modulation (PERM) is accomplished by active control involving periodic, low frequency fuel modulation, whereby low frequency fuel pulses are injected into the main fuel delivery. Importantly, the fuel pulses are injected at a rate so as not to affect the desired time-average equivalence ratio for the combustion device.
Attractiveness of periodic orbits in parametrically forced systems with time-increasing friction
Bartuccelli, Michele
Attractiveness of periodic orbits in parametrically forced systems with time- increasing friction with time-increasing friction Michele Bartuccelli,1,a) Jonathan Deane,1,b) and Guido Gentile2,c) 1 oscillator in the presence of friction, and study numerically how time-varying friction affects the dynamics
Solid State Division progress report for period ending September 30, 1990
Green, P.H.; Hinton, L.W. (eds.)
1991-03-01T23:59:59.000Z
This report covers research progress in the Solid State Division from April 1, 1989, to September 30, 1990. During this period, division research programs were significantly enhanced by the restart of the High-Flux Isotope Reactor (HFIR) and by new initiatives in processing and characterization of materials.
the past 150-year period of reported global Second, historical information on solar
compared with the radia- tive relaxation time of layers storing the heat blocked by sunspots. This timethe past 150-year period of reported global warming. Second, historical information on solar increase in solar activity beyond present levels might make the sun dimmer, decreasing its average out- put
Periodic Communication Logics for the Decentralized Control of Multi-Agent Systems
Lemmon, Michael
Periodic Communication Logics for the Decentralized Control of Multi-Agent Systems Yashan Sun decision is not related to the current state of the system. We say the communication logic is closed and Michael D. Lemmon Abstract-- This paper studies a system consisting of several dynamical subsystems
A PERIOD-BASED GROUP MEMBERSHIP STRATEGY FOR NODES OF TDMA NETWORKS
Koopman, Philip
In automotive embedded systems, all nodes are not created equal. Automotive embedded systems generally have different periods. Current automotive buses such as the Controller Area Network (CAN) use a priority in order to provide a more predictable platform for safety assurance. Time Division Multiple Access (TDMA
Periodic equivalence ratio modulation method and apparatus for controlling combustion instability
Richards, G.A.; Janus, M.C.; Griffith, R.A.
2000-05-09T23:59:59.000Z
The periodic equivalence ratio modulation (PERM) method and apparatus significantly reduces and/or eliminates unstable conditions within a combustion chamber. The method involves modulating the equivalence ratio for the combustion device, such that the combustion device periodically operates outside of an identified unstable oscillation region. The equivalence ratio is modulated between preselected reference points, according to the shape of the oscillation region and operating parameters of the system. Preferably, the equivalence ratio is modulated from a first stable condition to a second stable condition, and, alternatively, the equivalence ratio is modulated from a stable condition to an unstable condition. The method is further applicable to multi-nozzle combustor designs, whereby individual nozzles are alternately modulated from stable to unstable conditions. Periodic equivalence ratio modulation (PERM) is accomplished by active control involving periodic, low frequency fuel modulation, whereby low frequency fuel pulses are injected into the main fuel delivery. Importantly, the fuel pulses are injected at a rate so as not to affect the desired time-average equivalence ratio for the combustion device.
Covariation of coastal water temperature and microbial pollution at interannual to tidal periods
Winant, Clinton D.
% of the 21,349,000 acres of shellfish harvesting waters in the U.S. were harvest-limited due to FIBCovariation of coastal water temperature and microbial pollution at interannual to tidal periods 30 March 2004. [1] Water temperature and fecal indicator bacteria levels covary along the shoreline
HTGR gas-turbine program. Semiannual progress report for period ending March 31, 1980
Not Available
1982-01-01T23:59:59.000Z
This report describes the conceptual design and analysis performed by General Atomic Company and its subcontractors for the US Department of Energy on the direct cycle gas turbine high-temperature gas-cooled reactor. The primary accomplishments for this period were cost reduction studies, turbomachinery failure analysis, and alternate plant concept evaluation.
An analysis of tomb reliefs depicting boat construction from the Old Kingdom period in Egypt
Rogers, Edward Morgan
1996-01-01T23:59:59.000Z
Among the aspects of daily life represented on the walls of private tombs during the Old Kingdom in Egypt are reliefs depicting the construction of boat hulls. Examination of the twenty known reliefs and relief fragments which date to this period...
An analytic approximation to the Diffusion Coefficient for the periodic Lorentz Gas
C. Angstmann; G. P. Morriss
2012-02-14T23:59:59.000Z
An approximate stochastic model for the topological dynamics of the periodic triangular Lorentz gas is constructed. The model, together with an extremum principle, is used to find a closed form approximation to the diffusion coefficient as a function of the lattice spacing. This approximation is superior to the popular Machta and Zwanzig result and agrees well with a range of numerical estimates.
Hopf bifurcations to quasi-periodic solutions for the two-dimensional plane Poiseuille flow
Barcelona, Universitat de
the branch of periodic flows which are born at the Hopf bifurcation of the laminar flow. It is known that topics in fluid mechanics. Poiseuille as well as Taylor Couette flow are test problems where of their geometry. The dynamics of plane Poiseuille flow departs from the laminar flow. The stability of the laminar
Spectral correlations in systems undergoing a transition from periodicity to disorder T. Dittrich
Pollner, PÃ©ter
! for the periodic case. The theoretical results agree very well with the spectral statistics obtained numerically Departamento de Fï¿½ â?? sica, Universidad de los Andes, A.A. 4976, Santafe â?? de Bogota â?? , Colombia B. Mehlig 25 November 1998! We study the spectral statistics for extended yet finite quasi
Asymptotic Ruin Probabilities of the Lvy Insurance Model under Periodic Taxation
Tang, Qihe
and that taxes are paid at a ...xed rate 2 [0; 1) whenever S is at a running maximum (called the loss-called loss-carry-forward taxation, meaning that taxes are paid at a certain ...xed rate immediately when the surplus of the company is at a running maximum. In this paper we assume periodic taxation under which
QUANTUM ENERGY EXPECTATION IN PERIODIC TIME-DEPENDENT HAMILTONIANS VIA GREEN
QUANTUM ENERGY EXPECTATION IN PERIODIC TIME-DEPENDENT HAMILTONIANS VIA GREEN FUNCTIONS C´ESAR R. DE. Introduction 1 2. Average Energy and Green Functions 4 3. Applications 10 3.1. Time-Independent Hamiltonians 10(t). For each positive and discrete observable A (which we call a probe energy), we derive a formula
ccsd-00082860,version1-28Jun2006 A periodic microfluidic bubbling oscillator
Boyer, Edmond
&Gamble). For the dispersed gas phase we use nitrogen supplied from a pressurized tank via a pressure reduction valve microfoams in lab-on-a-chip systems. In this letter we will show the generation of a micro- foam at constant input parameters both gas flow rate and bub- ble volume show a large periodic oscillation. We can
Local field enhancement on metallic periodic surface structures produced by femtosecond laser pulses
Ionin, Andrei A; Kudryashov, Sergei I; Ligachev, A E; Makarov, Sergei V; Mel'nik, N N; Rudenko, A A; Seleznev, L V; Sinitsyn, D V; Khmelnitskii, R A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2013-04-30T23:59:59.000Z
Periodic surface structures on aluminium are produced by femtosecond laser pulses for efficient excitation of surface electromagnetic waves using a strong objective (NA = 0.5). The local electromagnetic field enhancement on the structures is measured using the technique of surface-enhanced Raman scattering from pyridine molecules. (extreme light fields and their applications)
A Novel Global Op-miza-on Approach to the Mul-period Blending Problem
Grossmann, Ignacio E.
Overall Flows Individual Components (Blending) · Flow/Inventory Bounds · OperaA Novel Global Op-miza-on Approach to the Mul-period Blending Problem Sco · Minimize total cost of blending opera-on Fs3,t Cs3 Fs2,t Cs2 Fd1,t CL d1-CU d1
UC Berkeley Heat/Ventilation Curtailment Period DECEMBER 24, 2011 through JANUARY 1, 2012
California at Irvine, University of
UC Berkeley Heat/Ventilation Curtailment Period DECEMBER 24, 2011 through JANUARY 1, 2012 Each year and January 1, 2012 in order to conserve energy, most campus buildings will be closed and heat and ventilation://hrweb.berkeley.edu/ for more information. Barrows Hall BUILDINGS SCHEDULED TO BE WITHOUT HEAT/VENTILATION Bechtel Engineering
Transiting Planets with LSST II. Period Detection of Planets Orbiting 1 Solar Mass Hosts
Jacklin, Savannah R; Pepper, Joshua; Stassun, Keivan G
2015-01-01T23:59:59.000Z
The Large Synoptic Survey Telescope (LSST) will photometrically monitor ~1 billion stars for ten years. The resulting light curves can be used to detect transiting exoplanets. In particular, as demonstrated by Lund et al. (2015), LSST will probe stellar populations currently undersampled in most exoplanet transit surveys, including out to extragalactic distances. In this paper we test the efficiency of the box-fitting least-squares (BLS) algorithm for accurately recovering the periods of transiting exoplanets using simulated LSST data. We model planets with a range of radii orbiting a solar-mass star at a distance of 7 kpc, with orbital periods ranging from 0.5 to 20 d. We find that typical LSST observations will be able to reliably detect Hot Jupiters with periods shorter than ~3 d. At the same time, we find that the LSST deep drilling cadence is extremely powerful: the BLS algorithm successfully recovers at least 30% of sub-Saturn-size exoplanets with orbital periods as long as 20 d.
All-sky search for periodic gravitational waves in the full S5 LIGO data
Barsotti, Lisa
We report on an all-sky search for periodic gravitational waves in the frequency band 50–800 Hz and with the frequency time derivative in the range of 0 through -6×10[superscript -9]??Hz/s. Such a signal could be produced ...
Switching periodic membranes via pattern transformation and shape memory Jongmin Shim,b
Switching periodic membranes via pattern transformation and shape memory effect Jie Li,a Jongmin in shape memory polymer (SMP) membranes consisting of a hexagonal array of micron-sized circular holes a stamp. In both scenarios, the original color displays can be recovered. Introduction Shape memory
Risk neutral valuation of options in multi-period discrete-time markets
Risk neutral valuation of options in multi- period discrete-time markets In this lecture we study is the discounted expectation of its payoff under a martingale measure and use it to price call and put options Let F be an algebra of subsets of the finite sample space . Definition. A real-valued function (or
Daraio, Chiara
2014-01-01T23:59:59.000Z
. INTRODUCTION The periodic arrangement of small-scale building blocks results in acoustic or mechanical directions [1012] as well as resonant phenomena capable of absorbing energy on lower scales by local engineered material systems leads to an interesting or ben- eficial effective dynamic behavior
JOURNAL DE PHYSIQUE IV Colloque C9, supplCmentau Journal de Physique III, Volume 4, novembre 1994
Boyer, Edmond
beamline (ID6) whose source is a high beta undulator (px=27m, Pz=13m). 2. SINGLELENS EXPERIMENTS 2.1 Setup. 3. HIGH ENERGY X-RAY TELESCOPE We used a 42mm-period undulator on the first harmonic (gap=45mm). The high energy x-ray telescope setup based on two circular BFL is presented in Fig.2. We used Si-444
Long Term Simulations Of Astrophysical Jets; Energy Structure and Quasi-Periodic Ejection
Ahmed Ibrahim; Kazunari Shibata
2007-04-23T23:59:59.000Z
We have performed self-consistent 2.5-dimensional nonsteady MHD numerical simulations of jet formation as long as possible, including the dynamics of accretion disks. Although the previous nonsteady MHD simulations for astrophysical jets revealed that the characteristics of nonsteady jets are similar to those of steady jets, the calculation time of these simulations is very short compared with the time scale of observed jets. Thus we have investigated long term evolutions of mass accretion rate, mass outflow rate, jet velocity, and various energy flux. We found that the ejection of jet is quasi-periodic. The period of the ejection is related to the time needed for the initial magnetic filed to be twisted to generate toroidal filed. We compare our results with both the steady state theory and previous 2.5-dimensional nonsteady MHD simulations.
Murphy, Ryan D. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)
2014-06-09T23:59:59.000Z
Laser-induced periodic surface structures (LIPSS) are formed near 110?nm-tall Au microstructured edges on Si substrates after single-pulse femtosecond irradiation with a 150 fs pulse centered near a 780 nm wavelength. We investigate the contributions of Fresnel diffraction from step-edges and surface plasmon polariton (SPP) excitation to LIPSS formation on Au and Si surfaces. For certain laser polarization vector orientations, LIPSS formation is dominated by SPP excitation; however, when SPP excitation is minimized, Fresnel diffraction dominates. The LIPSS orientation and period distributions are shown to depend on which mechanism is activated. These results support previous observations of the laser polarization vector influencing LIPSS formation on bulk surfaces.
Geometrical investigation of the kinetic evolution of the magnetic field in a periodic flux rope
Restante, A. L.; Lapenta, G. [Afdeling Plasma-astrofysica, Departement Wiskunde, KULeuven, University of Leuven, Leuven (Belgium)] [Afdeling Plasma-astrofysica, Departement Wiskunde, KULeuven, University of Leuven, Leuven (Belgium); Markidis, S. [High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden)] [High Performance Computing and Visualization (HPCViz) Department, KTH Royal Institute of Technology, Stockholm (Sweden); Intrator, T. [Los Alamos National Laboratory, M.S. E526, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, M.S. E526, Los Alamos, New Mexico 87545 (United States)
2013-08-15T23:59:59.000Z
Flux ropes are bundles of magnetic field wrapped around an axis. Many laboratory, space, and astrophysics processes can be represented using this idealized concept. Here, a massively parallel 3D kinetic simulation of a periodic flux rope undergoing the kink instability is studied. The focus is on the topology of the magnetic field and its geometric structures. The analysis considers various techniques such as Poincaré maps and the quasi-separatrix layer (QSL). These are used to highlight regions with expansion or compression and changes in the connectivity of magnetic field lines and consequently to outline regions where heating and current may be generated due to magnetic reconnection. The present study is, to our knowledge, the first QSL analysis of a fully kinetic 3D particle in cell simulation and focuses the existing QSL method of analysis to periodic systems.
Hydraulic Characteristics of the Lower Snake River During Periods of Juvenile Fall Chinook Migration
Cook, Chris B.; Dibrani, Berhon; Richmond, Marshall C.; Bleich, Matthew D.; Titzler, P. Scott; Fu, Tao
2006-01-30T23:59:59.000Z
This report documents a four-year study to assess hydraulic conditions in the lower Snake River. The work was conducted for the Bonneville Power Administration, U.S. Department of Energy, by the Pacific Northwest National Laboratory. Cold water released from the Dworshak Reservoir hypolimnion during mid- to late-summer months cools the Clearwater River far below equilibrium temperature. The volume of released cold water augments the Clearwater River, and the combined total discharge is on the order of the Snake River discharge when the two rivers meet at their confluence near the upstream edge of Lower Granite Reservoir. With typical temperature differences between the Clearwater and Snake rivers of 10°C or more during July and August, the density difference between the two rivers during summer flow augmentation periods is sufficient to stratify Lower Granite Reservoir as well as the other three reservoirs downstream. Because cooling of the river is desirable for migrating juvenile fall Chinook salmon (Oncorhynchus tshawytscha) during this same time period, the amount of mixing and cold water entrained into Lower Granite Reservoir’s epilimnion at the Clearwater/Snake River confluence is of key biological importance to juvenile fall Chinook salmon. Data collected during this project indicates the three reservoirs downstream of Lower Granite also stratify as direct result of flow augmentation from Dworshak Reservoir. These four lower Snake reservoirs are also heavily influenced by wind forcing at the water’s surface, and during periods of low river discharge, often behave like a two-layer lake. During these periods of stratification, lower river discharge, and wind forcing, the water in the upper layer of the reservoir is held in place or moves slightly upstream. This upper layer is also exposed to surface heating and may warm up to temperatures close to equilibrium temperature. The depth of this upper warm layer and its direction of travel may also be of key biological importance to juvenile fall Chinook salmon. This report describes field data collection, modeling, and analysis of hydrodynamic and temperature conditions in the Lower Granite Reservoir during the summer flow augmentation periods of 2002, 2003, and 2004 plus a brief one-week period in 2005 of Lower Monumental, Little Goose, and Lower Granite Reservoirs. Circulation patterns in all four lower Snake River reservoirs were numerically simulated for periods of 2002, 2003, 2004, and 2005 using CE-QUAL-W2. Simulation results show that these models are sufficiently capable of matching diurnal and long term temperature and velocity changes in the reservoirs. In addition, the confluence zone of the Clearwater and Snake rivers was modeled using the 3-D model Flow3-D. This model was used to better understand mixing processing and entrainment. Once calibrated and validated, the reservoir models were used to investigate downstream impacts of alternative reservoir operation schemes, such as increasing or decreasing the ratio of Clearwater to Snake discharge. Simulation results were also linked with the particle tracking model FINS to better understand alterations of integrated metrics due to alternative operation schemes. These findings indicate that significant alterations in water temperature throughout the lower Snake River are possible by altering hypolimnetic discharges from Dworshak Reservoir and may have a significant impact on the behavior of migrating juvenile fall Chinook salmon during periods of flow augmentation.
Entangled three-particle states in magnetic field: Periodic correlations and density matrices
Amitabha Chakrabarti; Anirban Chakraborti
2010-04-28T23:59:59.000Z
We present a novel study of the time evolutions of entangled states of three spin-1/2 particles in the presence of a constant external magnetic field, which causes the individual spins to precess and leads to remarkable periodicities in the correlations and density matrices. The emerging patterns of periodicity are studied explicitly for different entangled states and in detail for a particular initial configuration of the velocities. Contributions to precession of anomalous magnetic moments are analysed and general results are also obtained. We then introduce an electric field orthogonal to the magnetic field, linking to the preceding case via a suitable Lorentz transformation, and obtain the corresponding Wigner rotations of the spin states. Finally, we point out for the first time that the entangled states corresponding to well-known ones in the study of 3-particle entanglements, may be classified systematically using a particular coupling of three angular momenta.
Glann Seaborg's Contributions to Heavy Element Science and the Periodic Table
Hobart, David E. [Los Alamos National Laboratory
2012-08-17T23:59:59.000Z
In celebrating the centennial anniversary of the birth of Glenn T. Seaborg it is fitting that we recount and pay tribute to his legacy. Many know of the scientific accomplishments of this man who became a legend and anyone who has attended his lectures can attest to how informative, educational, and entertaining he was. He had a beguiling and whimsical sense of humor and used this to drive home his points and share his passion and quest for discovery. The periodic table is a fundamental cornerstone of science and remains a central unifying principal. Seaborg was the architect of the actinide series of elements and their proper placement in the periodic table and co-discoverer of ten transuranium elements - one of which bears his name, element 106, seaborgium. The work and achievements of this Nobel laureate have touched the lives of many and his legacy will continue for generations to come.
Optimized shooting method for finding periodic orbits of nonlinear dynamical systems
W. Dednam; A. E. Botha
2014-08-14T23:59:59.000Z
An alternative numerical method is developed to find stable and unstable periodic orbits of nonlinear dynamical systems. The method exploits the high-efficiency of the Levenberg-Marquardt algorithm for medium-sized problems and has the additional advantage of being relatively simple to implement. It is also applicable to both autonomous and non-autonomous systems. As an example of its use, it is employed to find periodic orbits in the R\\"ossler system, a coupled R\\"ossler system, as well as an eight-dimensional model of a flexible rotor-bearing; problems which have been treated previously via two related methods. The results agree with the previous methods and are seen to be more accurate in some cases. A simple implementation of the method, written in the Python programming language, is provided as an Appendix.
QUASI-PERIODIC FORMALDEHYDE MASER FLARES IN THE MASSIVE PROTOSTELLAR OBJECT IRAS 18566+0408
Araya, E. D. [Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States); Hofner, P.; Goss, W. M. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Kurtz, S. [Centro de RadioastronomIa y Astrofisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 3-72, 58089 Morelia, Michoacan (Mexico); Richards, A. M. S. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Linz, H. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Olmi, L. [University of Puerto Rico at Rio Piedras, Physics Department, P.O. Box 23343, San Juan, PR 00931 (Puerto Rico); Sewilo, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
2010-07-10T23:59:59.000Z
We report results of an extensive observational campaign of the 6 cm formaldehyde maser in the young massive stellar object IRAS 18566+0408 (G37.55+0.20) conducted from 2002 to 2009. Using the Arecibo Telescope, the Very Large Array, and the Green Bank Telescope, we discovered quasi-periodic formaldehyde flares (P {approx} 237 days). Based on Arecibo observations, we also discovered correlated variability between formaldehyde (H{sub 2}CO) and methanol (CH{sub 3}OH) masers. The H{sub 2}CO and CH{sub 3}OH masers are not spatially coincident, as demonstrated by different line velocities and high angular resolution MERLIN observations. The flares could be caused by variations in the infrared radiation field, possibly modulated by periodic accretion onto a young binary system.
Ozbay, E.; Tuttle, G.; Michel, E.; Ho, K.M.; Biswas, R.; Chan, C.T.; Soukoulis, C.
1995-04-11T23:59:59.000Z
A method is disclosed for fabricating a periodic dielectric structure which exhibits a photonic band gap. Alignment holes are formed in a wafer of dielectric material having a given crystal orientation. A planar layer of elongate rods is then formed in a section of the wafer. The formation of the rods includes the step of selectively removing the dielectric material of the wafer between the rods. The formation of alignment holes and layers of elongate rods and wafers is then repeated to form a plurality of patterned wafers. A stack of patterned wafers is then formed by rotating each successive wafer with respect to the next-previous wafer, and then placing the successive wafer on the stack. This stacking results in a stack of patterned wafers having a four-layer periodicity exhibiting a photonic band gap. 42 figures.
Analytical Chemistry Division. Annual progress report for period ending December 31, 1981
Lyon, W.S. (ed.)
1982-04-01T23:59:59.000Z
The functions of the Analytical Chemistry Division fall into three general categories: (1) analytical research, development, and implementation; (2) programmatic research, development and utilization; (3) technical support. The Division is organized into five major sections each of which may carry out any type of work falling into the thre categories mentioned above. Chapters 1 through 5 of this report highlight progress within the five sections which are: analytical methodology; mass and emission spectrometry; analytical technical support; bio/organic analysis section; and nuclear and radiochemical analysis. A short summary introduces each chapter to indicate work scope. Information about quality assurance and safety programs is presented in Chapter 6, along with a tabulation of analyses rendered. Chapter 7 covers supplementary activities. Chapter 8 is on presentation of research results (publications, articles reviewed or referred for periodicals). Approximately 56 articles, 31 proceedings publications and 33 reports have been published, and 119 oral presentations given during this reporting period.
Tracking multiple generation and suppression of secondary electrons on periodic triangular surface
Li, S.; Wang, J. G.; Zhu, M.; Peng, J. C.; Xie, J. L.; Wu, X. L.; Guo, L. T. [Laboratory on Science and Technology of High Power Microwave, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China)] [Laboratory on Science and Technology of High Power Microwave, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China); Chang, C.; Xiong, Z. F. [Laboratory on Science and Technology of High Power Microwave, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China) [Laboratory on Science and Technology of High Power Microwave, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China); Department of Engineering Physics, Tsinghua University, Beijing 10084 (China)
2013-12-15T23:59:59.000Z
To research the dynamic course of multipactor suppression on the periodically patterned surface, tens of electron collision processes are tracked by numerical calculation. The influences of microwave frequency, amplitude of RF electric field, slope angle, the local field enhancement, and the tilted incident electric field on the multipactor suppression are studied by tracking multi-generation electrons' trajectories, hopping and flight time, collision energy, and secondary emission yield. Meanwhile, the dynamic processes of secondary electrons on the periodic surface are analyzed by particle-in-cell (PIC) simulation. The PIC results are consistent with the analytical results in which the electrons fly reciprocatingly between the slopes and impact on the slopes; the methods of increasing the slope angle, enlarging the RF field, and lowering the frequency in a certain range are helpful to enhance the multipactor suppression steadily and persistently.
Quasi-periodic events in crystal plasticity and the self-organized avalanche oscillator
Stefanos Papanikolaou; Dennis M. Dimiduk; Woosong Choi; James P. Sethna; Michael D. Uchic; Chris F. Woodward; Stefano Zapperi
2013-05-11T23:59:59.000Z
When external stresses in a system - physical, social or virtual - are relieved through impulsive events, it is natural to focus on the attributes of these avalanches. However, during the quiescent periods in between, stresses may be relieved through competing processes, such as slowly flowing water between earthquakes or thermally activated dislocation flow between plastic bursts. Such unassuming, smooth responses can have dramatic effects on the avalanche properties. Here we report a thorough experimental investigation of slowly compressed Ni microcrystals, covering three orders of magnitude in nominal strain rate, that exhibits unconventional quasi-periodic avalanche bursts and higher critical exponents as the strain rate is decreased. Our analytic and computational study naturally extends dislocation avalanche modeling to incorporate dislocation relaxations and reveals the emergence of the self-organized avalanche oscillator, a novel critical state exhibiting oscillatory approaches toward a depinning critical point. We demonstrate that the predictions of our theory are faithfully exhibited in our experiments.
Short-rotation woody-crops program. Quarterly progress report for period ending May 31, 1981
Cushman, J.H.; Ranney, J.W.
1982-04-01T23:59:59.000Z
Progress of twenty projects in the Short Rotation Woody Crops Program is summarized for the period March 1 through May 31, 1981. Individual quarterly reports included from each of the projects discuss accomplishments within specific project objectives and identify recent papers and publications resulting from the research. The major project activities are species screening and genetic selection, stand establishment and cultural treatment, and harvest, collection, transportation, and storage.
Solid State Division progress report for period ending September 30, 1984
Green, P.H.; Watson, D.M. (eds.)
1985-03-01T23:59:59.000Z
During the reporting period, relatively minor changes have occurred in the research areas of interest to the Division. Nearly all the research of the Division can be classified broadly as mission-oriented basic research. Topics covered include: theoretical solid state physics; surface and near-surface properties of solids; defects in solids; transport properties of solids; neutron scattering; and preparation and characterization of research materials. (GHT)
Solid State Division progress report for period ending March 31, 1997
Green, P.H.; Hinton, L.W. [eds.
1997-12-01T23:59:59.000Z
This report covers research progress in the Solid State Division from April 1, 1995, through March 31, 1997. During this period, the division conducted a broad, interdisciplinary materials research program in support of Department of Energy science and technology missions. The report includes brief summaries of research activities in condensed matter theory, neutron scattering, synthesis and characterization of materials, ion beam and laser processing, and the structure of solids and surfaces. An addendum includes listings of division publications and professional activities.
Dissociation of nitrogen in a pulse-periodic dielectric barrier discharge at atmospheric pressure
Popov, N. A., E-mail: npopov@mics.msu.su [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)
2013-05-15T23:59:59.000Z
Nitrogen molecule dissociation in a pulse-periodic atmospheric-pressure dielectric barrier discharge is numerically analyzed. It is shown that the quenching rate of predissociation states at atmospheric pressure is relatively low and the production of nitrogen atoms in this case can be adequately described using the cross section for electron-impact dissociation of N{sub 2} molecules taken from the paper by P.C. Cosby [J. Chem. Phys. 98, 9544 (1993)].
Strain relaxation in short-period polar GaN/AlN superlattices
Kandaswamy, P. K.; Jalabert, D.; Monroy, E. [Equipe Mixte CEA-CNRS Nanophysique et Semiconducteurs, INAC/SP2M/NPSC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Bougerol, C. [Equipe Mixte CEA-CNRS Nanophysique et Semiconducteurs, Institut Neel, 25 rue des Martyrs, 38042 Grenoble (France); Ruterana, P. [CIMAP, CNRS-ENSICAEN-CEA-UCBN, 6 Boulevard du Marechal Juin, 14050 Caen Cedex (France)
2009-07-01T23:59:59.000Z
We have investigated the strain relaxation mechanisms in short-period polar GaN/AlN superlattices deposited by plasma-assisted molecular-beam epitaxy, and designed to display intersubband transitions at 1.55 mum. In a first stage, we have identified the growth conditions to minimize strain relaxation, using a Ga excess to reduce the (0001) surface free energy of both GaN and AlN. Under these growth conditions, crack propagation is not observed, even for the tensile-strained superlattices grown on GaN templates. The initial misfit relaxation in the vicinity of the buffer occurs by the formation of a-type dislocations. The final strain state of the superlattice, reached after 10-20 periods, is independent of the substrate (either GaN or AlN templates). Once the steady-state conditions are reached, we observe a periodic partial relaxation of quantum wells and barriers. High-resolution transmission electron microscopy indicates that the periodic relaxation can be related to the presence of basal and prismatic stacking faults creating clusters with an in-plane length of tens of nanometers. The effect of these defects on the optical performance of the superlattices is discussed by simulation of electronic structure using an 8x8kcentre dotp Schroedinger-Poisson solver. In the presence of basal stacking faults at the quantum well interfaces, the deviation of the e{sub 1}-e{sub 2} intersubband transition with respect to the nominal value is expected to be smaller than the measured absorption line width.
Markus Schmuck; Peter Berg
2012-04-30T23:59:59.000Z
We formally derive an effective catalyst layer model comprising the reduction of oxygen for periodically distributed pore geometries. By assumption, the pores are completely filled with water and the surrounding walls consist of catalyst particles which are attached to an electron conducting microstructure. The macroscopic transport equations are established by a multi-scale approach, based on microscopic phenomena at the pore level, and serve as a first step toward future optimization of catalyst layer designs.
Schmuck, Markus
2012-01-01T23:59:59.000Z
We formally derive an effective catalyst layer model comprising the reduction of oxygen for periodically distributed pore geometries. By assumption, the pores are completely filled with water and the surrounding walls consist of catalyst particles which are attached to an electron conducting microstructure. The macroscopic transport equations are established by a multi-scale approach, based on microscopic phenomena at the pore level, and serve as a first step toward future optimization of catalyst layer designs.
Quantum Energy Expectation in Periodic Time-Dependent hamiltonians via Green Functions
Cesar R. de Oliveira; Mariza S. Simsen
2009-07-31T23:59:59.000Z
Let $U_F$ be the Floquet operator of a time periodic hamiltonian $H(t)$. For each positive and discrete observable $A$ (which we call a {\\em probe energy}), we derive a formula for the Laplace time average of its expectation value up to time $T$ in terms of its eigenvalues and Green functions at the circle of radius $e^{1/T}$. Some simple applications are provided which support its usefulness.
A low-dimensional model system for quasi-periodic plasma perturbations
Constantinescu, D. [Department of Applied Mathematics, University of Craiova, Association Euratom-MECI (Romania); Dumbrajs, O. [Institute of Solid State Physics, University of Latvia, Association Euratom-UL (Latvia); Igochine, V.; Lackner, K.; Meyer-Spasche, R.; Zohm, H. [Max-Planck Institut fuer Plasmaphysik, Association Euratom-IPP (Germany)
2011-06-15T23:59:59.000Z
Larger scale plasma instabilities not leading to an immediate termination of a discharge often result in periodic nonlinear perturbations of the plasma. A minimal possible model is formulated for description of the system with drive and relaxation processes which have different time scales. The model is based on two equations: the first being responsible for the relaxation dynamics and the second for the drive. The model can be generalized to describe the pellet injection.
Exact periodic solutions of the Liouville equation and the "snake" of density in JET
Spineanu, F
2004-01-01T23:59:59.000Z
The "snake" is a persistent density perturbation at the rational q-surfaces after pellet injection. Together with other phenomena (density pinch and profile resiliancy) it can be traced back to the extremum of an action functional for line-vortices in 3D. In a field theoretical formulation this leads to the Liouville equation. We provide explicit method of calculating solutions to the Liouville eq. on periodic domains and obtain, in particular, localised perturbations similar to the experimentally observed "snakes".
A computerized methodology for selecting projects in multi-period bridge management systems
Rebolledo Valenzuela, Carlos Esteban
1990-01-01T23:59:59.000Z
-effective decisions in a short or in a long range scenario. The purpose of this research is to develop and computerize a multi- period optimization procedure that will select the best set of replacement/rehabilitation projects for a given system of bridges.... 1. 1 Project Significance According to a Report to Congress by the Federal Highway Administration (FHWA, 1987), it is estimated that more than $50 billion would be needed to replace or rehabilitate today's deficient bridges in the United States...
P. A. Patsis; E. M. Xilouris
2005-12-09T23:59:59.000Z
The vertical profiles of disc galaxies are built by the material trapped around stable periodic orbits, which form their "skeletons". According to this, the knowledge of the stability of the main families of periodic orbits in appropriate 3D models, can predict possible morphologies for edge-on disc galaxies. In a pilot survey we compare the orbital structures which lead to the appearance of "peanuts" and "X"-like features with the edge-on profiles of three disc galaxies (IC 2531, NGC 4013 and UGC 2048). The subtraction from the images of a model representing the axisymmetric component of the galaxies reveals the contribution of the non-axisymmetric terms. We find a direct correspondence between the orbital profiles of 3D bars in models and the observed main morphological features of the residuals. We also apply a simple unsharp masking technique in order to study the sharpest features of the images. Our basic conclusion is that the morphology of the boxy "bulges" of these galaxies can be explained by considering disc material trapped around stable 3D periodic orbits. In most models these building-blocks periodic orbits are bifurcated from the planar central family of a non-axisymmetric component, usually a bar, at low order vertical resonances. In such a case the boxy "bulges" are parts of bars seen edge-on. For the three galaxies we study the families associated with the "peanut" or "X"-shape morphology are most probably bifurcations at the vertical 2/1 or 4/1 resonance.
PARC Periodical-Volume 5, Issue 4 | Photosynthetic Antenna Research Center
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaPLawrence County,1980) |NumberOfMeasuringStations Jump to: navigation,DemandChargePeriod4 Jump
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousPlasmaPLawrence County,1980) |NumberOfMeasuringStations Jump to: navigation,DemandChargePeriod4
Peter Kuchment; Andrew Raich
2011-10-02T23:59:59.000Z
Precise asymptotics known for the Green's function of the Laplace operator have found their analogs for periodic elliptic operators of the second order at and below the bottom of the spectrum. Due to the band-gap structure of the spectra of such operators, the question arises whether similar results can be obtained near or at the edges of spectral gaps. As the result of this work shows, this is possible at a spectral edge in dimensions d>2.
Engineering Physics and Mathematics Division progress report for period ending December 31, 1992
Ward, R.C.
1993-05-01T23:59:59.000Z
In this report, our research is described through abstracts of journal articles, technical reports, and presentations organized into sections following the five major operating units in the division: Mathematical Sciences, Intelligent Systems, Nuclear Data and Measurement Analysis, Nuclear Analysis and Shielding, and the Engineering Physics Information Centers. Each section begins with an introduction highlighting honors, awards, and significant research accomplishments in that unit during the reporting period.
Piezoelectrics by Design: A Route through Short-period Perovskite Superlattices
Das, Hena; Saha-Dasgupta, T
2010-01-01T23:59:59.000Z
Using first-principles density functional theory, we study piezoelectricity in short-period superlattices made with combination of ferroelectric and paraelectric components and exhibiting polar discontinuities. We show that piezoelectric response of such a superlattice can be tuned both in terms of sign and magnitude with a choice of its components. As these superlattices with nonswitchable polarization do not undergo ferroelectric transitions, we predict them to exhibit a robust piezoelectric response with weaker temperature dependence compared to their bulk counterparts.
Partovi-Azar, Pouya
2015-01-01T23:59:59.000Z
We extend the method of Silvestrelli [P. L. Silvestrelli, J. Chem. Phys. 139, 054106 (2013)] to approximate long-range van der Waals interactions at the density functional theory level based on maximally localized Wannier functions combined with the quantum harmonic oscillator model, to periodic systems. Applying this scheme to study London dispersion forces between graphene and water layers, we demonstrate that collective many-body effects beyond simple additive pair-wise interactions are essential to accurately describe van der Waals forces.
Pouya Partovi-Azar; T. D. Kühne
2015-04-17T23:59:59.000Z
We extend the method of Silvestrelli [P. L. Silvestrelli, J. Chem. Phys. 139, 054106 (2013)] to approximate long-range van der Waals interactions at the density functional theory level based on maximally localized Wannier functions combined with the quantum harmonic oscillator model, to periodic systems. Applying this scheme to study London dispersion forces between graphene and water layers, we demonstrate that collective many-body effects beyond simple additive pair-wise interactions are essential to accurately describe van der Waals forces.
Concepts for operational period panel seal design at the Waste Isolation Pilot Plant
Hansen, F.D. [Sandia National Labs., Albuquerque, NM (United States); Lin, M.S. [Parsons, Brinckerhoff, Quade and Douglas, Inc., San Francisco, CA (United States); Van Sambeek, L.L. [RE/SPEC, Inc., Rapid City, SD (United States)
1993-07-01T23:59:59.000Z
Concepts for underground panel or drift seals at the Waste Isolation Pilot Plant are developed to satisfy sealing requirements of the operational period. The concepts are divided into two groups. In the ``NOW`` group, design concepts are considered in which a sleeve structure is installed in the panel access immediately after excavation and before waste is emplaced. In the ``LATER`` group, no special measures are taken during excavation or before waste emplacement; the seal is installed at a later date, perhaps up to 35 years after the drift is excavated. Three concepts are presented in both the NOW and LATER groups. A rigid sleeve, a yielding sleeve, and steel rings with inflatable tubes are proposed as NOW concepts. One steel ring concept and two concrete monoliths are proposed for seals emplaced in older drifts. Advantages and disadvantages are listed for each concept. Based on the available information, it appears most feasible to recommend a LATER concept using a concrete monolith as a preferred seal for the operational period. Each concept includes the potential of remedial grout and/or construction of a chamber that could be used for monitoring leakage from a closed panel during the operational period. Supporting in situ demonstrations of elements of the concepts are recommended.
Separation of suspended particles in microfluidic systems by directional-locking in periodic fields
John Herrmann; Michael Karweit; German Drazer
2009-04-16T23:59:59.000Z
We investigate the transport and separation of overdamped particles under the action of a uniform external force in a two-dimensional periodic energy landscape. Exact results are obtained for the deterministic transport in a square lattice of parabolic, repulsive centers that correspond to a piecewise-continuous linear-force model. The trajectories are periodic and commensurate with the obstacle lattice and exhibit phase-locking behavior in that the particle moves at the same average migration angle for a range of orientation of the external force. The migration angle as a function of the orientation of the external force has a Devil's staircase structure. The first transition in the migration angle was analyzed in terms of a Poincare map, showing that it corresponds to a tangent bifurcation. Numerical results show that the limiting behavior for impenetrable obstacles is equivalent to the high Peclet number limit in the case of transport of particles in a periodic pattern of solid obstacles. Finally, we show how separation occurs in these systems depending on the properties of the particles.
Chaotic Dynamics of One-Dimensional Systems with Periodic Boundary Conditions
Pankaj Kumar; Bruce N. Miller
2014-10-01T23:59:59.000Z
We provide appropriate tools for the analysis of dynamics and chaos for one-dimensional systems with periodic boundary conditions. Our approach allows for the investigation of the dependence of the largest Lyapunov exponent on various initial conditions of the system. The method employs an effective approach for defining the phase-space distance appropriate for systems with periodic boundary and allows for an unambiguous test-orbit rescaling in the phase space required to calculate the Lyapunov exponents. We elucidate our technique by applying it to investigate the chaotic dynamics of a one-dimensional plasma with periodic boundary. Exact analytic expressions are derived for the electric field and potential using Ewald sums thereby making it possible to follow the time-evolution of the plasma in simulation without any special treatment of the boundary. By employing a set of event-driven algorithms, we calculate the largest Lyapunov exponent, the radial distribution function and the kinetic pressure by following the evolution of the system in phase space without resorting to numerical manipulation of the equations of motion. Simulation results are presented and analyzed for the one-dimensional plasma with a view to examining the dynamical and chaotic behavior exhibited by small and large versions of the system.
Classification of Floquet Statistical Distribution for Time-Periodic Open Systems
Dong E. Liu
2015-04-07T23:59:59.000Z
How to understand the order of Floquet stationary states in the presence of external bath coupling and their statistical mechanics is challenging; the answers are important for preparations and control of those Floquet states. Here, we propose a scheme to classify the statistical distribution of Floquet states for time-periodic systems which couple to an external heat bath. If an effective Hamiltonian and a system-bath coupling operator, which are all time-independent, can be simultaneously obtained via a time-periodic unitary transformation, the statistical mechanics of the Floquet states is equivalent to the equilibrium statistical mechanics of the effective Hamiltonian. In the large driving frequency cases, we also show that the conditions of this theorem can be weakened to: the time-period part in the system Hamiltonian commutes with the system-bath coupling operator. A Floquet-Markov approach is applied to numerically compute the Floquet state occupation distribution of a bosonic chain, and the results agree with the theoretical predictions.
Do the recent severe droughts in the Amazonia have the same period of length?
Zou, Yong; Sampaio, Gilvan; Mário, Antônio; Kurths, Jürgen
2015-01-01T23:59:59.000Z
We propose a new measure based on drought period length to assess the temporal difference between the recent two severe droughts of 2005 and 2010 in the Amazonia. The sensitivity of the measure is demonstrated by disclosing the distinct spatial responding mechanisms of the Northeastern and Southwestern Amazon (NA, SA) to the surrounding sea surface temperature (SST) variabilities. The Pacific and Atlantic oceans have different roles on the precipitation patterns in Amazonia. More specifically, the very dry periods in the NA are influenced by El Ni\\~no events, while the very dry periods in the SA are affected by the anomalously warming of the SST in the North Atlantic. We show convincingly that the drought 2005 hit SA, which is caused by the North Atlantic only. There are two phases in the drought 2010: (i) it was started in the NA in August 2009 affected by the El Ni\\~no event, and (ii) later shifted the center of action to SA resulted from anomalously high SST in North Atlantic, which further intensifies the...
A search for periodicities from a ULX in the LINER galaxy NGC 4736
Avdan, H; Akyuz, A; Balman, S
2014-01-01T23:59:59.000Z
We report our findings on a new quasi-periodic oscillation (QPO) and a long period from the ultraluminous X-ray source (ULX) X-2 in nearby galaxy NGC 4736 based on the Chandra and XMM-Newton archival data. To examine the timing properties, power density spectra of the source have been obtained using Fast Fourier Transform. Also the spectral parameters of the source have been calculated by obtaining and fitting the energy spectra. Power density spectrum of this source reveals a QPO peak at $0.73_{-0.14}^{+0.16}$ mHz with an fractional rms variability of 16% using the Chandra data (in the year 2000-lower state of the source). The XMM-Newton data analysis indicates a peak at $0.53_{-0.35}^{+0.09}$ mHz with a fractional rms variation of 5% (in the year 2006-higher state of the source). These recovered QPOs overlap within errors and may be the same oscillation. In addition, we detect a long periodicity or a QPO in the Chandra data of about $(5.2\\pm2.0)\\times10^{-5}$ Hz ($\\sim$ 5.4 hrs) over 3 $\\sigma$ confidence l...
TESTING CONVECTIVE-CORE OVERSHOOTING USING PERIOD SPACINGS OF DIPOLE MODES IN RED GIANTS
Montalban, J.; Noels, A.; Dupret, M.-A.; Scuflaire, R. [Institut d'Astrophysique et Geophysique de l'Universite de Liege, Allee du six Aout, 17 B-4000 Liege (Belgium)] [Institut d'Astrophysique et Geophysique de l'Universite de Liege, Allee du six Aout, 17 B-4000 Liege (Belgium); Miglio, A. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)] [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Ventura, P. [Osservatorio Astronomico di Roma-INAF, via Frascati 33, I-00040 Monteporzio Catone, Rome (Italy)] [Osservatorio Astronomico di Roma-INAF, via Frascati 33, I-00040 Monteporzio Catone, Rome (Italy)
2013-04-01T23:59:59.000Z
Uncertainties on central mixing in main-sequence (MS) and core He-burning (He-B) phases affect key predictions of stellar evolution such as late evolutionary phases, chemical enrichment, ages, etc. We propose a test of the extension of extra-mixing in two relevant evolutionary phases based on period spacing ({Delta}P) of solar-like oscillating giants. From stellar models and their corresponding adiabatic frequencies (respectively, computed with ATON and LOSC codes), we provide the first predictions of the observable {Delta}P for stars in the red giant branch and in the red clump (RC). We find (1) a clear correlation between {Delta}P and the mass of the helium core (M{sub He}); the latter in intermediate-mass stars depends on the MS overshooting, and hence it can be used to set constraints on extra-mixing during MS when coupled with chemical composition; and (2) a linear dependence of the average value of the asymptotic period spacing (({Delta}P){sub a}) on the size of the convective core during the He-B phase. A first comparison with the inferred asymptotic period spacing for Kepler RC stars also suggests the need for extra-mixing during this phase, as evinced from other observational facts.
Imaging and Spectral Observations of Quasi-Periodic Pulsations in a Solar Flare
Li, D; Zhang, Q M
2015-01-01T23:59:59.000Z
We explore the Quasi-Periodic Pulsations (QPPs) in a solar flare observed by Fermi Gamma-ray Burst Monitor (GBM), Solar Dynamics Observatory (SDO), Solar Terrestrial Relations Observatory (STEREO), and Interface Region Imaging Spectrograph (IRIS) on 2014 September 10. QPPs are identified as the regular and periodic peaks on the rapidly-varying components, which are the light curves after removing the slowly-varying components. The QPPs display only three peaks at the beginning on the hard X-ray (HXR) emissions, but ten peaks on the chromospheric and coronal line emissions, and more than seven peaks (each peak is corresponding to a type III burst on the dynamic spectra) at the radio emissions. An uniform quasi-period about 4 minutes are detected among them. AIA imaging observations exhibit that the 4-min QPPs originate from the flare ribbon, and tend to appear on the ribbon front. IRIS spectral observations show that each peak of the QPPs tends to a broad line width and a red Doppler velocity at C I, O IV, Si ...
Interband Coherence Induced Correction to Adiabatic Pumping in Periodically Driven Systems
Hailong Wang; Longwen Zhou; Jiangbin Gong
2015-03-03T23:59:59.000Z
Periodic driving can create topological phases of matter absent in static systems. In terms of the displacement of the position expectation value of a time-evolving wavepacket in a closed system, a type of adiabatic dynamics in periodically driven systems is studied for general initial states possessing coherence between different Floquet bands. Under one symmetry assumption, the displacement of the wavepacket center over one adiabatic cycle is found to be comprised by two components independent of the time scale of the adiabatic cycle: a weighted integral of the Berry curvature summed over all Floquet bands, plus an interband coherence induced correction. The found correction is beyond a naive application of the quantum adiabatic theorem but survives in the adiabatic limit due to interband coherence. Our theoretical results are hence of general interest towards an improved understanding of the quantum adiabatic theorem. Our theory is checked using a periodically driven superlattice model with nontrivial topological phases. In addition to probing topological phase transitions, the adiabatic dynamics studied in this work is now also anticipated to be useful in manifesting coherence and decoherence effects in the representation of Floquet bands.
A triple origin for the lack of tight coplanar circumbinary planets around short-period binaries
Hamers, Adrian S; Zwart, Simon F Portegies
2015-01-01T23:59:59.000Z
Detection of transiting circumbinary planets is more tractable around short-period binaries, however, no such binaries were found with orbits shorter than 7 days. Short-period main sequence binaries have been suggested to form in triple systems, through a combination of secular Kozai-Lidov cycles and tidal friction (KLCTF). Here, we show that coplanar circumbinary transiting planets are unlikely to exist around short-period binaries, due to triple evolution. We use secular analysis, $N$-body simulations and analytic considerations as well as population synthesis models to characterize their overall properties. We find that the existence of a circumbinary planet in a triple is likely to produce one of the following outcomes. (1) Sufficiently massive planets in tight and/or coplanar orbits around the inner binary can partially or completely quench the KL evolution, `shielding' the inner binary from the secular effects of the tertiary, and not allowing the KLCTF process to take place. In this case, the inner bin...
Three Packets of Minerals of the Periodic Table of Chemical Elements and Chemical Compounds
Labushev, Mikhail M
2013-01-01T23:59:59.000Z
The concepts of alpha- and beta-packets of the periodic table of chemical elements and chemical compounds are defined. The first of the 47 minerals alpha-packets is composed. In it all minerals are arranged in increasing Iav index of proportionality of atomic weights of composing chemical elements, the same way as chemical elements are located in increasing atomic weights in the Periodic table. The packet includes 93 known minerals and two compounds - N2O5 and CO2 - being actually minerals. Beta-packet of oxides and hydroxides minerals includes 88 known minerals and five chemical compounds - N2O5, CO2, CO, SO3 and SO2. Two minerals of the packet have not been determined yet. Besides, beta-packet of minerals with sulfur, selenium or arsenic is composed, with one mineral not defined yet. The results of the calculations can be used for further development of the Periodic Table of Chemical Elements and Chemical Compounds and their properties investigation.
Three Packets of Minerals of the Periodic Table of Chemical Elements and Chemical Compounds
Mikhail M. Labushev
2013-03-20T23:59:59.000Z
The concepts of alpha- and beta-packets of the periodic table of chemical elements and chemical compounds are defined. The first of the 47 minerals alpha-packets is composed. In it all minerals are arranged in increasing Iav index of proportionality of atomic weights of composing chemical elements, the same way as chemical elements are located in increasing atomic weights in the Periodic table. The packet includes 93 known minerals and two compounds - N2O5 and CO2 - being actually minerals. Beta-packet of oxides and hydroxides minerals includes 88 known minerals and five chemical compounds - N2O5, CO2, CO, SO3 and SO2. Two minerals of the packet have not been determined yet. Besides, beta-packet of minerals with sulfur, selenium or arsenic is composed, with one mineral not defined yet. The results of the calculations can be used for further development of the Periodic Table of Chemical Elements and Chemical Compounds and their properties investigation.
QUASI-PERIODIC OSCILLATIONS AND BROADBAND VARIABILITY IN SHORT MAGNETAR BURSTS
Huppenkothen, Daniela; Watts, Anna L.; Uttley, Phil; Van der Horst, Alexander J.; Van der Klis, Michiel [Astronomical Institute ''Anton Pannekoek'', University of Amsterdam, Postbus 94249, 1090-GE Amsterdam (Netherlands); Kouveliotou, Chryssa [Office of Science and Technology, ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Goegues, Ersin [Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I -Tuzla, Istanbul 34956 (Turkey); Granot, Jonathan [The Open University of Israel, 1 University Road, P.O. Box 808, Ra'anana 43537 (Israel); Vaughan, Simon [X-Ray and Observational Astronomy Group, University of Leicester, Leicester LE1 7RH (United Kingdom); Finger, Mark H., E-mail: D.Huppenkothen@uva.nl [Universities Space Research Association, Huntsville, AL 35805 (United States)
2013-05-01T23:59:59.000Z
The discovery of quasi-periodic oscillations (QPOs) in magnetar giant flares has opened up prospects for neutron star asteroseismology. However, with only three giant flares ever recorded, and only two with data of sufficient quality to search for QPOs, such analysis is seriously data limited. We set out a procedure for doing QPO searches in the far more numerous, short, less energetic magnetar bursts. The short, transient nature of these bursts requires the implementation of sophisticated statistical techniques to make reliable inferences. Using Bayesian statistics, we model the periodogram as a combination of red noise at low frequencies and white noise at high frequencies, which we show is a conservative approach to the problem. We use empirical models to make inferences about the potential signature of periodic and QPOs at these frequencies. We compare our method with previously used techniques and find that although it is on the whole more conservative, it is also more reliable in ruling out false positives. We illustrate our Bayesian method by applying it to a sample of 27 bursts from the magnetar SGR J0501+4516 observed by the Fermi Gamma-ray Burst Monitor, and we find no evidence for the presence of QPOs in any of the bursts in the unbinned spectra, but do find a candidate detection in the binned spectra of one burst. However, whether this signal is due to a genuine quasi-periodic process, or can be attributed to unmodeled effects in the noise is at this point a matter of interpretation.
Femtosecond laser-induced periodic surface structure on the Ti-based nanolayered thin films
Petrovi?, Suzana M.; Gakovi?, B.; Peruško, D. [Institute of Nuclear Science—Vin?a, University of Belgrade, POB 522, 11001 Belgrade (Serbia)] [Institute of Nuclear Science—Vin?a, University of Belgrade, POB 522, 11001 Belgrade (Serbia); Stratakis, E. [Institute of Electronic Structure and Laser, Foundation for Research and Technology–Hellas, P.O. Box 1527, Gr-711 10 Heraklion (Greece) [Institute of Electronic Structure and Laser, Foundation for Research and Technology–Hellas, P.O. Box 1527, Gr-711 10 Heraklion (Greece); Department of Materials Science and Technology, University of Crete, 710 03 Heraklion, Crete (Greece); Bogdanovi?-Radovi?, I. [Ru?er Boškovi? Institute, P.O. Box 180, 10002 Zagreb (Croatia)] [Ru?er Boškovi? Institute, P.O. Box 180, 10002 Zagreb (Croatia); ?ekada, M. [Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)] [Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Fotakis, C. [Institute of Electronic Structure and Laser, Foundation for Research and Technology–Hellas, P.O. Box 1527, Gr-711 10 Heraklion (Greece) [Institute of Electronic Structure and Laser, Foundation for Research and Technology–Hellas, P.O. Box 1527, Gr-711 10 Heraklion (Greece); Department of Physics, University of Crete, 714 09 Heraklion, Crete (Greece); Jelenkovi?, B. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia)] [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia)
2013-12-21T23:59:59.000Z
Laser-induced periodic surface structures (LIPSSs) and chemical composition changes of Ti-based nanolayered thin films (Al/Ti, Ni/Ti) after femtosecond (fs) laser pulses action were studied. Irradiation is performed using linearly polarized Ti:Sapphire fs laser pulses of 40 fs pulse duration and 800 nm wavelength. The low spatial frequency LIPSS (LSFL), oriented perpendicular to the laser polarization with periods slightly lower than the irradiation wavelength, was typically formed at elevated laser fluences. On the contrary, high spatial frequency LIPSS (HSFL) with uniform period of 155 nm, parallel to the laser light polarization, appeared at low laser fluences, as well as in the wings of the Gaussian laser beam distribution for higher used fluence. LSFL formation was associated with the material ablation process and accompanied by the intense formation of nanoparticles, especially in the Ni/Ti system. The composition changes at the surface of both multilayer systems in the LSFL area indicated the intermixing between layers and the substrate. Concentration and distribution of all constitutive elements in the irradiated area with formed HSFLs were almost unchanged.
Looking for granulation and periodicity imprints in the sunspot time series
Lopes, Ilidio
2015-01-01T23:59:59.000Z
The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral density of daily data series using the Mexican hat wavelet, we found a power spectrum with a well-defined shape, characterized by three features. The first term is the 22 yr solar magnetic cycle, estimated in our work to be of 18.43 yr. The second term is related to the daily volatility of sunspots. This term is most likely produced by the turbulent motions linked to the solar granulation. The last term corresponds to a periodic source associated with the solar magnetic activity, for which the maximum of power spectral density occurs at 22.67 days. This value is part of the 22-27 day periodicity region that shows an above-average intensity in the power spectra. The origin of this 22.67 day periodic process is not clearly identified, and there is a possibility that it can be...
Liao, Yang; Cui, Yun; Qiao, Lingling; Bellouard, Yves; Sugioka, Koji; Cheng, Ya
2015-01-01T23:59:59.000Z
We present direct experimental observation of the morphological evolution during the formation of nanogratings with sub-100-nm periods with the increasing number of pulses. Theoretical simulation shows that the constructive interference of the scattering light from original nanoplanes will create an intensity maximum located between the two adjacent nanoplanes, resulting in shortening of the nanograting period by half. The proposed mechanism enables explaining the formation of nanogratings with periods beyond that predicted by the nanoplasmonic model.
de Aguiar, M.A.M.; Malta, C.P.; Baranger, M.; Davies, K.T.R.
1987-12-01T23:59:59.000Z
Numerical and analytical studies of the types of period n-upling bifurcations undergone by classical periodic trajectories of non-integrable Hamiltonians with two degrees of freedom are made. The Hamiltonians studied possess time reversal and reflection symmetries and we found that these symmetries give rise to additional types of period n-upling bifurcations. The analytical study explains most of the numerically observed birfucations. copyright 1987 Academic Press, Inc.
Gheorghe Mihai
2010-02-12T23:59:59.000Z
In this paper, a new mathematical method of electrical circuits calculus is proposed based on the theory of the complex linear operators in matrix form. The newly proposed method generalizes the theory of complex representation of electrical quantities in sinusoidal periodic regime to the non-sinusoidal periodic regime.
Optical Klystron Enhancement to SASE X-ray FELs
Ding, Yuantao; Emma, Paul; Huang, Zhirong; Kumar, Vinit
2006-04-07T23:59:59.000Z
The optical klystron enhancement to self-amplified spontaneous emission (SASE) free electron lasers (FELs) is studied in theory and in simulations. In contrast to a seeded FEL, the optical klystron gain in a SASE FEL is not sensitive to any phase mismatch between the radiation and the microbunched electron beam. The FEL performance with the addition of four optical klystrons located at the undulator long breaks in the Linac Coherent Light Source (LCLS) shows significant improvement if the uncorrelated energy spread at the undulator entrance can be controlled to a very small level. In addition, FEL saturation at shorter x-ray wavelengths (around 1.0 A) within the LCLS undulator length becomes possible. We also discuss the application of the optical klystron in a compact x-ray FEL design that employs relatively low electron beam energy together with a shorter-period undulator.
Impact of Paint Color on Rest Period Climate Control Loads in Long-Haul Trucks: Preprint
Lustbader, J.; Kreutzer, C.; Jeffers, M.; Adelman, S.; Yeakel, S.; Brontz, P.; Olson, K.; Ohlinger, J.
2014-02-01T23:59:59.000Z
Cab climate conditioning is one of the primary reasons for operating the main engine in a long-haul truck during driver rest periods. In the United States, sleeper cab trucks use approximately 667 million gallons of fuel annually for rest period idling. The U.S. Department of Energy's National Renewable Energy Laboratory's (NREL) CoolCab Project works closely with industry to design efficient thermal management systems for long-haul trucks that minimize engine idling and fuel use while maintaining occupant comfort. Heat transfer to the vehicle interior from opaque exterior surfaces is one of the major heat pathways that contribute to air conditioning loads during long-haul truck daytime rest period idling. To quantify the impact of paint color and the opportunity for advanced paints, NREL collaborated with Volvo Group North America, PPG Industries, and Dometic Environmental Corporation. Initial screening simulations using CoolCalc, NREL's rapid HVAC load estimation tool, showed promising air-conditioning load reductions due to paint color selection. Tests conducted at NREL's Vehicle Testing and Integration Facility using long-haul truck cab sections, 'test bucks,' showed a 31.1% of maximum possible reduction in rise over ambient temperature and a 20.8% reduction in daily electric air conditioning energy use by switching from black to white paint. Additionally, changing from blue to an advanced color-matched solar reflective blue paint resulted in a 7.3% reduction in daily electric air conditioning energy use for weather conditions tested in Colorado. National-level modeling results using weather data from major U.S. cities indicated that the increase in heating loads due to lighter paint colors is much smaller than the reduction in cooling loads.
Paris-Sud XI, Université de
/Simulink simulations. Key words: power system harmonics, power electronic, linear time periodic modeling, PWM, control1 POWER ELECTRONICS HARMONIC ANALYSIS BASED ON THE LINEAR TIME PERIODIC MODELING. APPLICATIONS in power electronic systems. The considered system is described by a set of differential equations, which
ern Ocean was much more vigorous in the period from 1350 to 1880 A.D. than in the
Zhou, Chongwu
. Oceanogr. 14, 666 (1984). 19. Evidence of deep penetration of CFCs in the Southern Ocean [A. H. Orsi, G. Cern Ocean was much more vigorous in the period from 1350 to 1880 A.D. than in the recent past. Our of a subordinate role for deep convection in the Southern Ocean during this time period (21). Our conclusion
Daley, Monica A.
disruption or severe weather conditions GUIDANCE ON EMPLOYEE ATTENDANCE AT WORK DURING PERIODS OF MAJOR TRAVEL DISRUPTION OR SEVERE WEATHER CONDITIONS 1.0 INTRODUCTION AND SCOPE 1.1 The College's expectation work and returning home during periods of severe weather or when there are major travel disruptions. 1
Gajic, Zoran
3.6 Fourier Analysis MATLAB Laboratory Experiment Purpose: This experiment demonstrates approximations of periodic signals by truncated Fourier series as defined in formula (3.4). Using MATLAB students, and to find the system response due to periodic inputs. Part 1. Find the trigonometric form of the Fourier
Effect of nanodot areal density and period on thermal conductivity in SiGe/Si nanodot superlattices
Haller, Gary L.
Effect of nanodot areal density and period on thermal conductivity in SiGe/Si nanodot superlattices-plane thermal conductivity in SiGe/Si nanodot superlattices NDSLs . For all ND areal densities considered, we found that in SiGe/Si NDSLs decreased monotonically with decreasing period and reached values lower than
The Effect of Periodic Silane Burst on the Properties of GaN on Si (111) Substrates
Zang, Keyan
The periodic silane burst technique was employed during metalorganic chemical vapor deposition of epitaxial GaN on AlN buffer layers grown on Si (111). Periodic silicon delta doping during growth of both the AlN and GaN ...
03.612 Time Off for Voting. 1. Purpose. To provide staff members a reasonable period of time off
03.612 Time Off for Voting. 1. Purpose. To provide staff members a reasonable period of time off a reasonable period of time off during the regular work day for voting on an official election day. This time should be reported as time worked and is not charged against vacation leave, comp time or salary
Toru Miyazawa
2011-12-26T23:59:59.000Z
We consider one-dimensional Fokker-Planck and Schr\\"odinger equations with a potential which approaches a periodic function at spatial infinity. We extend the low-energy expansion method, which was introduced in previous papers, to be applicable to such asymptotically periodic cases. Using this method, we study the low-energy behavior of the Green function.
and differentially reallocate energy among these output variables. The way that animals prioritize the allocation516 Energy Reallocation during and after Periods of Nutritional Stress in Steller Sea Lions: Low subjected to periods of energy restriction and subsequent re- feeding during winter and summer to determine
Marques, Francisco
period T , St = h2 /T . The two-dimensional time-periodic basic state consists of the boundary layer at x= ± /2; b oscillatory glass floor; c end walls at z= ± /2; d floor of the acrylic con- tainer; e dynamic seals; f free-surface groove and solid wall position at y=h; g Teflon slide pads for oscillatory
1O.-ON THE INFLUENCE OF LIGHT ON THE PERIODICAL DEPTH-MIGRATIONS OF PELAGIC ANIMAIS
1O.-ON THE INFLUENCE OF LIGHT ON THE PERIODICAL DEPTH- MIGRATIONS OF PELAGIC ANIMAIS BY JACQUES it certain that this periodical depth migration of sea animals is determitied to a certain extent at least and of freshawater lakes is confined chiefly to two regions, one extending from the surface of the sea to a depth