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.
Configurations for short period rf undulators
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Kuzikov, S. V.; Jiang, Y.; Marshall, T. C.; Sotnikov, G. V.; Hirshfield, J. L.
2013-07-01T23:59:59.000Z
Several configurations for rf undulators energized at millimeter wavelengths and designed to produce coherent nanometer radiation from sub-GeV electron beams are analyzed and compared with one another. These configurations include a traveling-wave resonant ring, a standing wave resonator, and a resonator operating close to cutoff.
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...
Cooperative accumulation of coherent undulator radiation emitted from periodic electron bunches
Seo, Y. H. [Department of Electrophysics, Kwangwoon University, Seoul 139-701 (Korea, Republic of)
2013-01-15T23:59:59.000Z
Cavity build-up of coherent undulator synchrotron radiation emitted by periodic electron bunches is investigated. At the optimal off-grazing resonance, the bunch slippage relative to the radiation pulse introduces an initial transient period during which radiation accumulates cooperatively as if it is emitted by a single bunch. The power growth during the period is quadratic to the number of bunches. The number of cooperative bunches is {approx}2 Script-Small-L {sub s}{sup 2}, where Script-Small-L {sub s} denotes the slippage length in units of the resonant wavelength.
Fabrication of a Short-Period Nb3Sn Superconducting Undulator
Dietderich, Daniel; Dietderich, Daniel; Godeke, Arno; Prestemon, Soren; Pipersky, Paul T.; Liggins, Nate L.; Higley, Hugh C.; Marks, Steve; Schlueter, Ross D.
2007-06-01T23:59:59.000Z
Lawrence Berkeley National Laboratory develops high-field Nb{sub 3}Sn magnets for HEP applications. In the past few years, this experience has been extended to the design and fabrication of undulator magnets. Some undulator applications require devices that can operate in the presence of a heat load from a beam. The use of Nb{sub 3}Sn permits operation of a device at both a marginally higher temperature (5-8K) and a higher J{sub c}, compared to NbTi devices, without requiring a larger magnetic gap. A half-undulator device consisting of 6 periods (12 coil packs) of 14.5 mm period was designed, wound, reacted, potted and tested. It reached the short sample current limit of 717A in 4 quenches. The non-Cu Jc of the strand was over 7,600 A/mm{sup 2} and the Cu current density at quench was over 8,000 A/mm{sup 2}. Magnetic field models show that if a complete device was fabricated with the same parameters one could obtain beam fields of 1.1 T and 1.6 T for pole gaps of 8 mm and 6 mm, respectively.
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.
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.
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.
LCLS-II Undulator Tolerance Analysis
Nuhn, H.-D.; /SLAC; Marks, S.; /LBL, Berkeley; Wu, J.; /SLAC
2012-06-06T23:59:59.000Z
The SLAC National Accelerator Laboratory is building a new FEL user facility, LCLS-II, as a major upgrade to the Linear Coherent Light Source (LCLS). The upgrade will include two new Free Electron Lasers (FELs), to generate soft (SXR) and hard x-ray (HXR) SASE FEL radiation, based on planar, variable gap hybrid undulators with two different undulator periods (SXU: 55 mm, HXU: 32 mm). An algebraic FEL tolerance analysis for the undulator lines, including tuning, alignment, and phase correction tolerances has been performed. The methods and results are presented in this paper.
Crossed elliptical polarization undulator
Sasaki, Shigemi
1997-05-01T23:59:59.000Z
The first switching of polarization direction is possible by installing two identical helical undulators in series in a same straight section in a storage ring. By setting each undulator in a circular polarization mode in opposite handedness, one can obtain linearly polarized radiation with any required polarization direction depending on the modulator setting between two undulators. This scheme can be used without any major degradation of polarization degree in any low energy low emittance storage ring.
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.
Reference Undulator Measurement Results
Wolf, Zachary; Levashov, Yurii; /SLAC; ,
2011-08-18T23:59:59.000Z
The LCLS reference undulator has been measured 22 times during the course of undulator tuning. These measurements provide estimates of various statistical errors. This note gives a summary of the reference undulator measurements and it provides estimates of the undulator tuning errors. We measured the reference undulator many times during the tuning of the LCLS undulators. These data sets give estimates of the random errors in the tuned undulators. The measured trajectories in the reference undulator are stable and straight to within {+-}2 {micro}m. Changes in the phase errors are less than {+-}2 deg between data sets. The phase advance in the cell varies by less than {+-}2 deg between data sets. The rms variation between data sets of the first integral of B{sub x} is 9.98 {micro}Tm, and the rms variation of the second integral of B{sub x} is 17.4 {micro}Tm{sup 2}. The rms variation of the first integral of B{sub y} is 6.65 {micro}Tm, and the rms variation of the second integral of B{sub y} is 12.3 {micro}Tm{sup 2}. The rms variation of the x-position of the fiducialized beam axis is 35 {micro}m in the final production run This corresponds to an rms uncertainty in the K value of {Delta}K/K = 2.7 x 10{sup -5}. The rms variation of the y-position of the fiducialized beam axis is 4 {micro}m in the final production run.
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.
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.
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.
Performance Evaluation of Undulator Radiation at CEBAF
Chuyu Liu, Geoffrey Krafft, Guimei Wang
2010-05-01T23:59:59.000Z
The performance of undulator radiation (UR) at CEBAF with a 3.5 m helical undulator is evaluated and compared with APS undulator-A radiation in terms of brilliance, peak brilliance, spectral flux, flux density and intensity distribution.
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.
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...
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.
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
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.
New Science with the APS Superconducting Undulator
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| 2003 | 2002 | 2001 2000 Subscribe to APS News rss feed New Science with the APS Superconducting Undulator JULY 24, 2013 Bookmark and Share The Nature Materials cover. From...
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.
LCLS Undulator Quadrupole Fiducialization Plan
Wolf, Zachary; Levashov, Michael; Lundahl, Eric; Reese, Ed; LeCocq, Catherine; Ruland, Robert; /SLAC; ,
2010-11-24T23:59:59.000Z
This note presents the fiducialization plan for the LCLS undulator quadrupoles. The note begins by summarizing the requirements for the fiducialization. A 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 formats are presented. The LCLS is made up of 33 assemblies consisting of an undulator, quadrupole, beam finder wire, and other components mounted on a girder. The components must be mounted in such a way that the beam passes down the axis of each component. In this note, we describe how the ideal beam axis is related to tooling balls on the quadrupole. This step, called fiducialization, is necessary because the ideal beam axis is determined magnetically, whereas tangible objects must be used to locate the quadrupole. The note begins with the list of fiducialization requirements. The laboratory in which the work will be performed and the relevant equipment is then briefly described. This is followed by a discussion of the methods used to perform the fiducialization and the methods used to check the results. A detailed fiducialization plan is presented in which all the steps of fiducialization are enumerated. A discussion of the resulting data files and directory structure concludes the note.
Algorithms to Automate LCLS Undulator Tuning
Wolf, Zachary
2010-12-03T23:59:59.000Z
Automation of the LCLS undulator tuning offers many advantages to the project. Automation can make a substantial reduction in the amount of time the tuning takes. Undulator tuning is fairly complex and automation can make the final tuning less dependent on the skill of the operator. Also, algorithms are fixed and can be scrutinized and reviewed, as opposed to an individual doing the tuning by hand. This note presents algorithms implemented in a computer program written for LCLS undulator tuning. The LCLS undulators must meet the following specifications. The maximum trajectory walkoff must be less than 5 {micro}m over 10 m. The first field integral must be below 40 x 10{sup -6} Tm. The second field integral must be below 50 x 10{sup -6} Tm{sup 2}. The phase error between the electron motion and the radiation field must be less than 10 degrees in an undulator. The K parameter must have the value of 3.5000 {+-} 0.0005. The phase matching from the break regions into the undulator must be accurate to better than 10 degrees. A phase change of 113 x 2{pi} must take place over a distance of 3.656 m centered on the undulator. Achieving these requirements is the goal of the tuning process. Most of the tuning is done with Hall probe measurements. The field integrals are checked using long coil measurements. An analysis program written in Matlab takes the Hall probe measurements and computes the trajectories, phase errors, K value, etc. The analysis program and its calculation techniques were described in a previous note. In this note, a second Matlab program containing tuning algorithms is described. The algorithms to determine the required number and placement of the shims are discussed in detail. This note describes the operation of a computer program which was written to automate LCLS undulator tuning. The algorithms used to compute the shim sizes and locations are discussed.
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.
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 ...
Air Temperature in the Undulator Hall
Not Available
2010-12-07T23:59:59.000Z
Various analyses have been performed recently to estimate the performance of the air conditioning (HVAC) system planned for the Undulator Hall. This reports summarizes the results and provides an upgrade plan to be used if new requirements are needed in the future. The estimates predict that with the planned loads the tunnel air temperature will be well within the allowed tolerance during normal operation.
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 Long Coil Measurement System Tests
Wolf, Zachary; Levashov, Yurii; /SLAC; ,
2010-11-24T23:59:59.000Z
The first and second field integrals in the LCLS undulators must be below a specified limit. To accurately measure the field integrals, a long coil system is used. This note describes a set of tests which were used to check the performance of the long coil system. A long coil system was constructed to measure the first and second field integrals of the LCLS undulators. The long coil measurements of the background fields were compared to field integrals obtained by sampling the background fields and numerically calculating the integrals. This test showed that the long coil has the sensitivity required to measure at the levels specified for the field integrals. Tests were also performed by making long coil measurements of short magnets of known strength placed at various positions The long coil measurements agreed with the known field integrals obtained by independent measurements and calculation. Our tests showed that the long coil measurements are a valid way to determine whether the LCLS undulator field integrals are below the specified limits.
Magnetic Measurement Results of the LCLS Undulator Quadrupoles
Anderson, Scott; Caban, Keith; Nuhn, Heinz-Dieter; Reese, Ed; Wolf, Zachary; /SLAC; ,
2011-08-18T23:59:59.000Z
This note details the magnetic measurements and the magnetic center fiducializations that were performed on all of the thirty-six LCLS undulator quadrupoles. Temperature rise, standardization reproducibility, vacuum chamber effects and magnetic center reproducibility measurements are also presented. The Linac Coherent Light Source (LCLS) undulator beam line has 33 girders, each with a LCLS undulator quadrupole which focuses and steers the beam through the beam line. Each quadrupole has main quadrupole coils, as well as separate horizontal and vertical trim coils. Thirty-six quadrupoles, thirty-three installed and three spares were, manufactured for the LCLS undulator system and all were measured to confirm that they met requirement specifications for integrated gradient, harmonics and for magnetic center shifts after current changes. The horizontal and vertical dipole trims of each quadrupole were similarly characterized. Each quadrupole was also fiducialized to its magnetic center. All characterizing measurements on the undulator quads were performed with their mirror plates on and after a standardization of three cycles from -6 to +6 to -6 amps. Since the undulator quadrupoles could be used as a focusing or defocusing magnet depending on their location, all quadrupoles were characterized as focusing and as defocusing quadrupoles. A subset of the undulator quadrupoles were used to verify that the undulator quadrupole design met specifications for temperature rise, standardization reproducibility and magnetic center reproducibility after splitting. The effects of the mirror plates on the undulator quadrupoles were also measured.
A Benchmark Construction of Positron Crystal Undulator
Tikhomirov, Victor V
2015-01-01T23:59:59.000Z
Optimization of a positron crystal undulator (CU) is addressed. The ways to assure both the maximum intensity and minimum spectral width of positron CU radiation are outlined. We claim that the minimum CU spectrum width of 3 -- 4% is reached at the positron energies of a few GeV and that the optimal bending radius of crystals planes in CU ranges from 3 to 5 critical bending radii for channeled particles. Following suggested approach a benchmark positron CU construction is devised and its functioning is illustrated using the simulation method widely tested by experimental data.
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.
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.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Variable Polarizing Undulator Device Length 4.8 m Undulator Period 12.5 cm First Harmonic Range 250 to 2500 eV (Horizontal Linear Polarization) 440 to 2500 eV (Vertical Linear...
Position Stability Monitoring of THEthe LCLS Undulator Quadrupoles
Nuhn, Heinz Dieter; Gassner, Georg; Peters, Franz; /SLAC
2012-03-26T23:59:59.000Z
X-ray FELs demand that the positions of undulator components be stable to less than 1 {mu}m per day. Simultaneously, the undulator length increases significantly in order to saturate at x-ray wavelengths. To minimize the impact of the outside environment, the Linac Coherent Light Source (LCLS) undulator is placed underground, but reliable data about ground motion inside such a tunnel was not available in the required stability range during the planning phase. Therefore, a new position monitor system had been developed and installed with the LCLS undulator. This system is capable of measuring x, y, roll, pitch and yaw of each of the 33 undulator quadrupoles with respect to stretched wires. Instrument resolution is about 10 nm and instrument drift is negligible. Position data of individual quadrupoles can be correlated along the entire 132-m long undulator. The system has been under continuous operation since 2009. This report describes long term experiences with the running system and the observed positional stability of the undulator quadrupoles.
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.
SCIENTIFIC POTENTIAL AND DESIGN CONSIDERATIONS FOK AN UNDULATOR...
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design approach. A tunable "clamshell" undulator device was cnosen with a first harmonic tunable from 35 to 110 eV to operate on a 1 GeV storage ring. Higher harmonics will...
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.
On the Kinematics of Undulator Girder Motion
Welch, J; /SLAC; ,
2011-08-18T23:59:59.000Z
The theory of rigid body kinematics is used to derive equations that govern the control and measurement of the position and orientation of undulator girders. The equations form the basis of the girder matlab software on the LCLS control system. The equations are linear for small motion and easily inverted as desired. For reference, some relevant girder geometrical data is also given. Equations 6-8 relate the linear potentiometer readings to the motion of the girder. Equations 9-11 relate the cam shaft angles to the motion of the girder. Both sets are easily inverted to either obtain the girder motion from the angles or readings, or, to find the angles and readings that would give a desired motion. The motion of any point on the girder can be calculated by applying either sets of equations to the two cam-planes and extrapolating in the z coordinate using equation 19. The formulation of the equations is quite general and easily coded via matrix and vector methods. They form the basis of the girder matlab software on the LCLS control system.
First results of a superconducting undulator on the ACO storage ring (*) (**)
Paris-Sud XI, Université de
L-547 First results of a superconducting undulator on the ACO storage ring (*) (**) C. Bazin (1), M. 2014 A superconducting undulator has been fixed on the ACO storage ring. It has been observed
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...
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.
Influence of surface traction on soft robot undulation
Liu, David R.
, assist in human motor tasks, and reduce manufacturing costs. As with natural invertebrates, soft robotsArticle Influence of surface traction on soft robot undulation The International Journal of Robotics Research 32(13) 15771584 © The Author(s) 2013 Reprints and permissions: sagepub
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.
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.
A. B. Kukushkin; V. A. Rantsev-Kartinov
2002-05-30T23:59:59.000Z
The presence of skeletal structures of the same distinctive topology (cartwheels, tubules, etc.), in the range 10^{-5} - 10^23 cm, and a trend toward self-similarity of these structures are found. These evidences come from the electron micrography of dust deposits in tokamak (10^{-6} - 10^{-3}cm), the images of plasma taken in laboratory electric discharges -- tokamaks, Z-pinches, plasma focus and vacuum spark (10^{-2} - 10 cm), hail particles (1-10 cm), the images of tornado (10^3 - 10^5 cm), the Hubble Space Telescope and Chandra X-Ray Observatory public archives' images (up to 10^23 cm). The redshift surveys of galaxies and quasars suggests the possibility to draw the above similarity farther, up to 10^26 cm. The above similarity hints at the presence of a baryonic cold dark skeleton (BCDS) of the Universe, which -- in the entire range 10^{-5} - 10^26 cm -- may contain ordinary matter in a fractal condensed form like that in the above-mentioned dust skeletons and hail particles. The probable compatibility of the BCDS with the major cosmological facts (Hubble's expansion and cosmic microwave background) is suggested. Our former hypotheses (and the respective proof-of-concept studies) for the probable microscopic mechanisms of skeleton's assembling, chemical composition, and survivability in ambient hot plasmas are discussed briefly. The respective major cosmological implication is that the purely gravitational description of the large-scale structure of the Universe is likely to be appended with a contribution of quantum electromagnetism, presumably in the form of a skeleton self-assembled from tubular nanostructures (carbon nanotubes or similar nanostructures of other chemical elements).
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.
The E166 Experiment: Undulator-Based Production of Polarized Positrons
Schuler, K.Peter; /DESY
2007-10-29T23:59:59.000Z
A proof-of-principle experiment has been carried out in the Final Focus Test Beam (FFTB) at SLAC to demonstrate production of polarized positrons in a manner suitable for implementation at the ILC. A helical undulator of 2.54 mm period and 1-m length produced circularly polarized photons of first harmonic endpoint energy of 8 MeV when traversed by a 46.6 GeV electron beam. The polarized photons were converted to polarized positrons in a 0.2-radiation-length tungsten target. The polarization of these positrons was measured at several energies, with a peak value of {approx} 80% according to a preliminary analysis of the transmission polarimetry of photons obtained on reconversion of the positrons in a second tungsten target.
The E166 Experiment: Undulator-Based Production of Polarized Positrons
Schueler, K. Peter [DESY, D-22607 Hamburg (Germany)
2008-02-06T23:59:59.000Z
A proof-of-principle experiment has been carried out in the Final Focus Test Beam (FFTB) at SLAC to demonstrate production of polarized positrons in a manner suitable for implementation at the ILC. A helical undulator of 2.54 mm period and 1-m length produced circularly polarized photons of first harmonic endpoint energy of 8 MeV when traversed by a 46.6 GeV electron beam. The polarized photons were converted to polarized positrons in a 0.2-radiation-length tungsten target. The polarization of these positrons was measured at several energies, with a peak value in excess of 80%, by transmission polarimetry of photons obtained on reconversion of the positrons in a second tungsten target.
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
Optimization of the LCLS X-ray FEL output performance in the presence of strong undulator wakefields
Reiche, S; Emma, P; Fawley, W M; Huang, Z; Nuhn, H D; Stupakov, G V
2005-01-01T23:59:59.000Z
Optimization of the LCLS X-ray FEL output performance in the presence of strong undulator wakefields
Bane, K L F; Tu, J J
2006-01-01T23:59:59.000Z
Reflectivity Measurements for Copper and Aluminumin the Far Infrared and the Resistive Wall Impedance in the LCLS Undulator
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
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.
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.
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....
Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic
Bakeman, M.S.; Van Tilborg, J.; Nakamura, K.; Gonsalves, A.; Osterhoff, J.; Sokollik, T.; Lin, C.; Robinson, K.E.; Schroeder, C.B.; Toth, Cs.; Weingartner, R.; Gruner, F.; Esarey, E.; Leemans, W.P.
2010-06-01T23:59:59.000Z
The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented.
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.
Levashov, Yu.
2010-12-13T23:59:59.000Z
Fiducialization of the LCLS undulators will be based on magnetic measurements by Hall probe. Pointed magnets, proposed by I.Vasserman for quadrupole lens fiducialization will be used as an intermediate reference. A prototype of the pointed magnet fixture has been made and tested. In this note we will describe a procedure for measuring the position of the center of the Hall probe sensitive area with respect to the undulator fiducial marks. The pointed magnet calibration procedure, a two-point algorithm for locating the magnetic center of the fixture, and test results are presented.
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.
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.
Roughness Tolerance Studies for the Undulator Beam Pipe Chamber of LCLS-II
Bane, K
2014-01-01T23:59:59.000Z
We investigate the effect of wall roughness on the wakefield-induced energy variation in the undulator beam pipe of LCLS-II. We find that a wall roughness equivalent to an rms surface slope of 30 mr increases the total induced energy variation within the bunch (due to the resistive wall wake) by a modest 20%.
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
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.
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
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
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
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.
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
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
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.
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.
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
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Protection Obeying Environmental Laws Individual Permit Storm Water Analytical Period Storm Water Analytical Period The Individual Permit authorizes the discharge of storm...
Shu, D.; Kuzay, T.M.
1995-10-20T23:59:59.000Z
A compact filter/mask/window assembly has been designed for undulator beamline commissioning activity at the Advanced Photon Source beamlines. The assembly consists of one 300-{mu}m graphite filter, one 127-{mu}m CVD diamond filter and two 250-{mu}m beryllium windows. A water-cooled Glidcop fixed mask with a 4.5-mm {times} 4.5-mm output optical aperture and a 0.96-mrad {times} 1.6-mrad beam missteering acceptance is a major part in the assembly. The CVD diamond filter which is mounted on the downstream side of the fixed mask is designed to also function as a transmitting x-ray beam position monitor. The sum signal from the latter can be used to monitor the physical condition of the graphite filter and prevent any possible chain reaction damage to the beryllium windows downstream. In this paper, the design concept as well as the detailed structural design of the commissioning window are presented. Further applications of the commissioning window commissioning window components are also discussed.
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: 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...
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
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
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 ...
LCLS CDR Chapter 8 - Undulator
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9 5 - -/e),,s - 6157Bioenergy09913 35 FEL78
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.
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.
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.
Compact betatron with four controlling-field periodicity elements
Chakhlov, V.L.; Pushin, V.S.; Burov, G.I.; Zvontsov, A.A.; Zvorygin, V.P.; Zrelov, Yu.D.
1987-01-01T23:59:59.000Z
A compact 3-MeV betatron is described. The electromagnet of the betatron uses removable four-element poles, which form a magnetic field with azimuthal variation. The betatron accelerates 2 x 10/sup 10/ particles per cycle. The cycle repetition frequency is up to 400 Hz. The radius of the equilibrium orbit is 4.5 cm. The maximum interpole gap is 4 cm. The depth of magnetic-field variation on the equilibrium radius is 0.15.
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.
Broadband solar absorption enhancement via periodic
Province, 230009, P. R. China. Solution processed colloidal quantum dot (CQD) solar cells have greatBroadband solar absorption enhancement via periodic nanostructuring of electrodes Michael M. Adachi demonstrate a bottom- illuminated periodic nanostructured CQD solar cell that enhances broadband absorption
Metallurgy Department Progress Report for the Period
Dlcfc^ooWS imsm "-"' Metallurgy Department Progress Report for the Period 1 January to 31 December 1962 (Uw National Laboratory, DK-4000 Roskilde, Denmark July 1963 #12;Risø-R-486 METALLURGY DEPARTMENT PROGRESS REPORT FOR THE PERIOD 1 JANUARY TO 31 DECEMBER 1982 Abstract. The activities of the Metallurgy
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.
DEVELOPMENT OF RASASASTRA IN MEDIEVAL PERIOD*
Harishankar Sharma
1984-01-01T23:59:59.000Z
ABSTRACT: The paper deals with the historical development of Rasasastra in Medieval period. Knowledge of Rasa has been in existence from the time immemorial. Exploration of natural resources for the benefit of human beings is the object of this therapy. It is a medical science recognized during vedic periods for the betterment of even Devas. Medieval period can be treated as a golden age for the development of this science. Looking at its aim and objects, methodology and therapeutics, it was recognized as a medical science with an independent philosophical background in 14 th century, by Madhavacharya in his Sarva Darsana Samgraha.
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
Paris-Sud XI, UniversitÃ© de
periods often appear in industry due to a machine breakdown (stochastic) or preventive maintenance of machine unavailability. However, in some cases (e.g. preventive maintenance), the maintenance of a machineSingle-machine scheduling with periodic and exible periodic maintenance to minimize maximum
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...
Enforcement Policy Statement: Compliance Period for Regional...
Broader source: Energy.gov (indexed) [DOE]
Compliance Period for Regional Standards Applicable to Central Air Conditioners April 24, 2014 On June 27, 2011, the U.S. Department of Energy (DOE) published in the Federal...
Analytical homogenization method for periodic composite materials
Chen, Ying
We present an easy-to-implement technique for determining the effective properties of composite materials with periodic microstructures, as well as the field distributions in them. Our method is based on the transformation ...
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.
Periodic subsystem density-functional theory
Genova, Alessandro; Pavanello, Michele, E-mail: m.pavanello@rutgers.edu [Department of Chemistry, Rutgers University, Newark, New Jersey 07102 (United States); Ceresoli, Davide [Department of Chemistry, Rutgers University, Newark, New Jersey 07102 (United States); CNR-ISTM, Institute of Molecular Sciences and Technologies, Milano (Italy)
2014-11-07T23:59:59.000Z
By partitioning the electron density into subsystem contributions, the Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) has recently emerged as a powerful tool for reducing the computational scaling of Kohn–Sham DFT. To date, however, FDE has been employed to molecular systems only. Periodic systems, such as metals, semiconductors, and other crystalline solids have been outside the applicability of FDE, mostly because of the lack of a periodic FDE implementation. To fill this gap, in this work we aim at extending FDE to treat subsystems of molecular and periodic character. This goal is achieved by a dual approach. On one side, the development of a theoretical framework for periodic subsystem DFT. On the other, the realization of the method into a parallel computer code. We find that periodic FDE is capable of reproducing total electron densities and (to a lesser extent) also interaction energies of molecular systems weakly interacting with metallic surfaces. In the pilot calculations considered, we find that FDE fails in those cases where there is appreciable density overlap between the subsystems. Conversely, we find FDE to be in semiquantitative agreement with Kohn–Sham DFT when the inter-subsystem density overlap is low. We also conclude that to make FDE a suitable method for describing molecular adsorption at surfaces, kinetic energy density functionals that go beyond the GGA level must be employed.
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.
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
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
Utility Building Analysis Billing Period: NOV -2013
Ciocan-Fontanine, Ionut
ELECTRICITY Consumption MUNICIPAL WATER Consumption 8 CCF STEAM Consumption CHILLED WATER Consumption GAS Building Analysis Billing Period: NOV - 2013 032 JACKSON HALL: 150,393 Square Feet ELECTRICITY Consumption,550 Square Feet ELECTRICITY Consumption 114,185 KWHRS MUNICIPAL WATER Consumption 1,423 CCF STEAM Consumption
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
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.
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.
Policy Flash 2013-41 Contracts Periods of Performance Exceeding...
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41 Contracts Periods of Performance Exceeding 5 Years Policy Flash 2013-41 Contracts Periods of Performance Exceeding 5 Years Attached is Policy Flash 2013-41 Contracts Periods of...
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
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.
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.
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Periodic Cluster Mutations and Related Integrable Maps
Allan P Fordy
2014-03-31T23:59:59.000Z
One of the remarkable properties of cluster algebras is that any cluster, obtained from a sequence of mutations from an initial cluster, can be written as a Laurent polynomial in the initial cluster (known as the "Laurent phenomenon"). There are many nonlinear recurrences which exhibit the Laurent phenomenon and thus unexpectedly generate integer sequences. The mutation of a typical quiver will not generate a recurrence, but rather an erratic sequence of exchange relations. How do we "design" a quiver which gives rise to a given recurrence? A key role is played by the concept of "periodic cluster mutation", introduced in 2009. Each recurrence corresponds to a finite dimensional map. In the context of cluster mutations, these are called "cluster maps". What properties do cluster maps have? Are they integrable in some standard sense? In this review I describe how integrable maps arise in the context of cluster mutations. I first explain the concept of "periodic cluster mutation", giving some classification results. I then give a review of what is meant by an integrable map and apply this to cluster maps. Two classes of integrable maps are related to interesting monodromy problems, which generate interesting Poisson algebras of functions, used to prove complete integrability and a linearisation. A connections to the Hirota-Miwa equation is explained.
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.
Quasi-Periodic Oscillations from Magnetorotational Turbulence
Phil Arras; Omer Blaes; Neal J. Turner
2006-02-13T23:59:59.000Z
Quasi-periodic oscillations (QPOs) in the X-ray lightcurves of accreting neutron star and black hole binaries have been widely interpreted as being due to standing wave modes in accretion disks. These disks are thought to be highly turbulent due to the magnetorotational instability (MRI). We study wave excitation by MRI turbulence in the shearing box geometry. We demonstrate that axisymmetric sound waves and radial epicyclic motions driven by MRI turbulence give rise to narrow, distinct peaks in the temporal power spectrum. Inertial waves, on the other hand, do not give rise to distinct peaks which rise significantly above the continuum noise spectrum set by MRI turbulence, even when the fluid motions are projected onto the eigenfunctions of the modes. This is a serious problem for QPO models based on inertial waves.
Periodic table for topological insulators and superconductors
Alexei Kitaev
2009-01-20T23:59:59.000Z
Gapped phases of noninteracting fermions, with and without charge conservation and time-reversal symmetry, are classified using Bott periodicity. The symmetry and spatial dimension determines a general universality class, which corresponds to one of the 2 types of complex and 8 types of real Clifford algebras. The phases within a given class are further characterized by a topological invariant, an element of some Abelian group that can be 0, Z, or Z_2. The interface between two infinite phases with different topological numbers must carry some gapless mode. Topological properties of finite systems are described in terms of K-homology. This classification is robust with respect to disorder, provided electron states near the Fermi energy are absent or localized. In some cases (e.g., integer quantum Hall systems) the K-theoretic classification is stable to interactions, but a counterexample is also given.
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.
Steady periodic gravity waves with surface tension
Samuel Walsh
2009-11-06T23:59:59.000Z
In this paper we consider two-dimensional, stratified, steady water waves propagating over an impermeable flat bed and with a free surface. The motion is assumed to be driven by capillarity (that is, surface tension) on the surface and a gravitational force acting on the body of the fluid. We prove the existence of global continua of classical solutions that are periodic and traveling. This is accomplished by first constructing a 1-parameter family of laminar flow solutions, $\\mathcal{T}$, then applying bifurcation theory methods to obtain local curves of small amplitude solutions branching from $\\mathcal{T}$ at an eigenvalue of the linearized problem. Each solution curve is then continued globally by means of a degree theoretic theorem in the spirit of Rabinowitz. Finally, we complement the degree theoretic picture by proving an alternate global bifurcation theorem via the analytic continuation method of Dancer.
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.
CEQ Extends Comment Period on Revised Draft Guidance on Consideration...
Broader source: Energy.gov (indexed) [DOE]
comment period on its revised draft guidance on consideration of greenhouse gas (GHG) emissions and the effects of climate change in NEPA reviews. The comment period now ends on...
Transition Period High Water Marks - May 2009.indd
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
the Contract High Water Mark (CHWM) contracts in May 2009, BPA is publishing initial Transition Period High Water Marks (THWMs) and Above-Rate-Period High Water Mark (Above-RHWM)...
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
Focusing-to-defocusing crossover in nonlinear periodic structures
Focusing-to-defocusing crossover in nonlinear periodic structures Francis H. Bennet,* InÃ©s A. Amuli
Quarterly Construction Status Report Period Ending: June 30, 2013
Alpay, S. Pamir
Quarterly Construction Status Report Period Ending: June 30, 2013 Storrs and Regional Campuses University of Connecticut Health Center Quarterly Construction Status Report for Period Ending: June 30, 2013 #12;Quarterly Construction Status Report Period Ending: June 30, 2013 Project Number Project Index
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
Period of K system generator of pseudorandom numbers
Akopov, N Z; Floratos, Emmanuel G; Savvidy, G K
1996-01-01T23:59:59.000Z
We analyze the structure of the periodic trajectories of the matrix generator of pseudorandom numbers which has been proposed earlier. The structure of the periodic trajectories becomes more transparent when the rational sublattice coincides with the Galois field GF[p]. We are able to compute the period of the trajectories as a function of p and the dimension of the matrix d.
Period of K System Generator of Pseudorandom Numbers
N. Z. Akopov; G. G. Athanasiu; E. G. Floratos; G. K. Savvidy
1996-02-09T23:59:59.000Z
We analyze the structure of the periodic trajectories of the matrix generator of pseudorandom numbers which has been proposed earlier. The structure of the periodic trajectories becomes more transparent when the rational sublattice coincides with the Galois field $GF[p]$. We are able to compute the period of the trajectories as a function of $p$ and the dimension of the matrix $d$.
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
Quarterly Construction Status Report Period Ending: March 31, 2014
Alpay, S. Pamir
Quarterly Construction Status Report Period Ending: March 31, 2014 Storrs and Regional Campuses University of Connecticut Health Center Quarterly Construction Status Report for Period Ending: March 31, 2014 #12;Quarterly Construction Status Report Period Ending: March 31, 2014 Project Number Project
Period-luminosity and period-luminosity-colour relations for Mira variables at maximum light
S. M. Kanbur; M. A. Hendry; D. Clarke
1997-04-14T23:59:59.000Z
In this paper we confirm the existence of period-luminosity (PL) and period-luminosity-colour (PLC) relations at maximum light for O and C Mira variables in the LMC. We demonstrate that in the J and H bands the maximum light PL relations have a significantly smaller dispersion than their counterparts at mean light, while the K band and bolometric PL relations have a dispersion comparable to that at mean light. In the J, H and K bands the fitted PL relations for the O Miras are found to have smaller dispersion than those for the C Miras, at both mean and maximum light, while the converse is true for the relations based on bolometric magnitudes. The inclusion of a non-zero log period term is found to be highly significant in all cases except that of the C Miras in the J band, for which the data are found to be consistent with having constant absolute magnitude. This suggests the possibility of employing C Miras as standard candles. We suggest both a theoretical justification for the existence of Mira PL relations at maximum light and a possible explanation of why these relations should have a smaller dispersion than at mean light. The existence of such maximum light relations offers the possibility of extending the range and improving the accuracy of the Mira distance scale to Galactic globular clusters and to other galaxies.
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...
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.
EIS-0250: Notice of Public Comment Period Extension and Additional...
Broader source: Energy.gov (indexed) [DOE]
Period Extension and Additional Public Meeting Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County, NV...
Uranium Leasing Program Draft PEIS Public Comment Period Extended...
Broader source: Energy.gov (indexed) [DOE]
Uranium Leasing Program Draft PEIS Public Comment Period Extended to May 31, 2013 Draft ULPEIS comment extension community notification041813 (3).pdf More Documents & Publications...
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 ...
CV evolution: AM Her binaries and the period gap
R. F. Webbink; D. T. Wickramasinghe
2002-04-19T23:59:59.000Z
AM Her variables -- synchronised magnetic cataclysmic variables (CVs) -- exhibit a different period distribution from other CVs across the period gap. We show that non-AM Her systems may infiltrate the longer-period end of the period gap if they are metal-deficient, but that the position and width of the gap in orbital period is otherwise insensitive to other binary parameters (excepting the normalisation of the braking rate). In AM Her binaries, magnetic braking is reduced as the wind from the secondary star may be trapped within the magnetosphere of the white dwarf primary. This reduced braking fills the period gap from its short-period end as the dipole magnetic moment of the white dwarf increases. The consistency of these models with the observed distribution of CVs, both AM Her and non-AM Her type, provides compelling evidence supporting magnetic braking as the agent of angular momentum loss among long-period CVs, and its disruption as the explanation of the 2 - 3 hour period gap among nonmagnetic CVs.
Extension of Comment Period on the Draft Integrated, Interagency...
Extension of Comment Period on the Draft Integrated, Interagency Pre-Application (IIP) Process for Electric Transmission Projects Requiring Federal Authorizations Extension of...
Phase-locked rhythms in periodically stimulated heart cell aggregates
Glass, Leon
Phase-locked rhythms in periodically stimulated heart cell aggregates MICHAEL R. GUEVARA, ALVIN GUEVARA,MICHAEL R., ALVIN SHRIER,ANDLEONGLASS. Phase-locked rhythms in periodically stimulated heart cell, THE SINOATRIAL NODE acts as the pace- maker of the heart. As a result of the orderly spread of excitation
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
TIME-PERIODIC SOUND WAVE PROPAGATION COMPRESSIBLE EULER EQUATIONS
A PARADIGM FOR TIME-PERIODIC SOUND WAVE PROPAGATION IN THE COMPRESSIBLE EULER EQUATIONS BLAKE consistent with time-periodic sound wave propagation in the 3 Ã? 3 nonlinear compressible Euler equations description of shock-free waves that propagate through an oscillating entropy field without breaking or dis
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.
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
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
On the Mass-Period Correlation of the Extrasolar Planets
Shay Zucker; Tsevi Mazeh
2002-02-22T23:59:59.000Z
We report on a possible correlation between the masses and periods of the extrasolar planets, manifested as a paucity of massive planets with short orbital periods. Monte-Carlo simulations show the effect is significant, and is not solely due to an observational selection effect. We also show the effect is stronger than the one already implied by published models that assumed independent power-law distributions for the masses and periods of the extrasolar planets. Planets found in binary stellar systems may have an opposite correlation. The difference is highly significant despite the small number of planets in binary systems. We discuss the paucity of short-period massive planets in terms of some theories for the close-in giant planets. Almost all models can account for the deficit of massive planets with short periods, in particular the model that assumes migration driven by a planet-disk interaction, if the planet masses do not scale with their disk masses.
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
Mo, Yi-Lung; Stokoe, Kenneth H.; Perkins, Judy; Tang, Yu
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.
ancient glacial periods: Topics by E-print Network
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15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 MECHANISMS OF ABRUPT CLIMATE CHANGE OF THE LAST GLACIAL PERIOD Geosciences Websites Summary: MECHANISMS OF...
Wave propagation in periodic lattices with defects of smaller dimension
A. A. Kutsenko
2013-05-20T23:59:59.000Z
The procedure of evaluating of the spectrum for discrete periodic operators perturbed by operators of smaller dimensions is obtained. This result allows to obtain propagative, guided, localised spectra for different kind of physical operators on graphs with defects.
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.
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, ...
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information about Weber, Rodney 19 Type II and IV radio bursts in the active period October-November 2003 CERN Preprints Summary: In this report we present the Type II and IV...
Optimization models for improving periodic maintenance schedules by utilizing opportunities
Patriksson, Michael
to this as preventive maintenance activities at an oppor- tunity. The original opportunistic replacement problemOptimization models for improving periodic maintenance schedules by utilizing opportunities Torgny of Technology Abstract We present mathematical models for finding optimal opportunistic maintenance schedules
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WITH PERIODIC ACTIVE THERMAL IMAGING Physics Websites Summary: methods where the thermal evolution of a scene is recorded while some external time varying energyIMPACT OF A LOSSY...
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
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Variable Selection and Inference for Multi-period Forecasting Problems
Pesaran, M Hashem; Pick, Andreas; Timmermann, Allan
Variable Selection and Inference for Multi-period Forecasting Problems? M. Hashem Pesaran Cambridge University and USC Andreas Pick De Nederlandsche Bank and Cambridge University, CIMF Allan Timmermann UC San Diego and CREATES January 26, 2009...
Ultrasonic wave propagation in random and periodic particulate composites
Henderson, Benjamin Kyle
1996-01-01T23:59:59.000Z
ULTRASONIC WAVE PROPAGATION IN RANDOM AND PERIODIC PARTICULATE COMPOSITES A Thesis by BENJAMIN KYLE HENDERSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfilltnent of the requirements for the degree... of MASTER OF SCIENCE May 1996 Major Subject: Aerospace Engineering ULTRASONIC WAVE PROPAGATION IN RANDOM AND PERIODIC PARTICULATE COMPOSITES A Thesis by BENJAMIN KYLE HENDERSON Submitted to Texas ASM University in partial fulfillment...
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.
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.
Intermittent and sustained periodic windows in networked chaotic Rössler oscillators
He, Zhiwei; Sun, Yong [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China) [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhan, Meng, E-mail: zhanmeng@wipm.ac.cn [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)] [Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)
2013-12-15T23:59:59.000Z
Route to chaos (or periodicity) in dynamical systems is one of fundamental problems. Here, dynamical behaviors of coupled chaotic Rössler oscillators on complex networks are investigated and two different types of periodic windows with the variation of coupling strength are found. Under a moderate coupling, the periodic window is intermittent, and the attractors within the window extremely sensitively depend on the initial conditions, coupling parameter, and topology of the network. Therefore, after adding or removing one edge of network, the periodic attractor can be destroyed and substituted by a chaotic one, or vice versa. In contrast, under an extremely weak coupling, another type of periodic window appears, which insensitively depends on the initial conditions, coupling parameter, and network. It is sustained and unchanged for different types of network structure. It is also found that the phase differences of the oscillators are almost discrete and randomly distributed except that directly linked oscillators more likely have different phases. These dynamical behaviors have also been generally observed in other networked chaotic oscillators.
Time-periodic solutions of the Benjamin-Ono equation
Ambrose , D.M.; Wilkening, Jon
2008-04-01T23:59:59.000Z
We present a spectrally accurate numerical method for finding non-trivial time-periodic solutions of non-linear partial differential equations. The method is based on minimizing a functional (of the initial condition and the period) that is positive unless the solution is periodic, in which case it is zero. We solve an adjoint PDE to compute the gradient of this functional with respect to the initial condition. We include additional terms in the functional to specify the free parameters, which, in the case of the Benjamin-Ono equation, are the mean, a spatial phase, a temporal phase and the real part of one of the Fourier modes at t = 0. We use our method to study global paths of non-trivial time-periodic solutions connecting stationary and traveling waves of the Benjamin-Ono equation. As a starting guess for each path, we compute periodic solutions of the linearized problem by solving an infinite dimensional eigenvalue problem in closed form. We then use our numerical method to continue these solutions beyond the realm of linear theory until another traveling wave is reached (or until the solution blows up). By experimentation with data fitting, we identify the analytical form of the solutions on the path connecting the one-hump stationary solution to the two-hump traveling wave. We then derive exact formulas for these solutions by explicitly solving the system of ODE's governing the evolution of solitons using the ansatz suggested by the numerical simulations.
Counting of Sieber-Richter pairs of periodic orbits
Gutkin, Boris
2011-01-01T23:59:59.000Z
In the framework of the semiclassical approach the universal spectral correlations in the Hamiltonian systems with classical chaotic dynamics can be attributed to the systematic correlations between actions of periodic orbits which (up to the switch in the momentum direction) pass through approximately the same points of the phase space. By considering symbolic dynamics of the system one can introduce a natural ultrametric distance between periodic orbits and organize them into clusters. Each cluster consists of orbits approaching closely each other in the phase space. We study the distribution of cluster sizes for the backer's map in the asymptotic limit of long trajectories. This problem is equivalent to the one of counting degeneracies in the length spectrum of the {\\it de Bruijn} graphs. Based on this fact, we derive the probability $\\P_k$ that $k$ randomly chosen periodic orbits belong to the same cluster. Furthermore, we find asymptotic behaviour of the largest cluster size $|\\Cll_{\\max}|$ and derive th...
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.
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.
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.
Phase transitions in full counting statistics for periodic pumping
Dmitri A. Ivanov; Alexander G. Abanov
2010-07-16T23:59:59.000Z
We discuss the problem of full counting statistics for periodic pumping. The probability generating function is usually defined on a circle of the "physical" values of the counting parameter, with its periodicity corresponding to charge quantization. The extensive part of the generating function can either be an analytic function on this circle or have singularities. These two cases may be interpreted as different thermodynamic phases in time domain. We discuss several examples of phase transitions between these phases for classical and quantum systems. Finally, we prove a criterion for the "analytic" phase in the problem of a quantum pump for noninteracting fermions.
Controlling mobility via rapidly oscillating time-periodic stimulus
Prasun Sarkar; Alok Kumar Maity; Anindita Shit; Sudip Chattopadhyay; Jyotipratim Ray Chaudhuri; Suman K Banik
2014-03-26T23:59:59.000Z
To address the dynamics of a Brownian particle on a periodic symmetric substrate under high-frequency periodic forcing with a vanishing time average, we construct an effective Langevin dynamics by invoking Kapitza-Landau time window. Our result is then exploited to simulate the mobility both for original and effective dynamics which are in good agreement with theoretical predictions. This close agreement and the enhancement of mobility are very robust against the tailoring of amplitude-to-frequency ratio which substantiates the correctness of our calculation. Present results may be illuminating for understanding the dynamics of cold atoms in electromagnetic fields.
Overall Dynamic Properties of 3-D periodic elastic composites
Ankit Srivastava; Sia Nemat-Nasser
2011-05-27T23:59:59.000Z
A method for the homogenization of 3-D periodic elastic composites is presented. It allows for the evaluation of the averaged overall frequency dependent dynamic material constitutive tensors relating the averaged dynamic ?eld variable tensors of velocity, strain, stress, and linear momentum. The formulation is based on micromechanical modeling of a representative unit cell of a composite proposed by Nemat-Nasser & Hori (1993), Nemat-Nasser et. al. (1982) and Mura (1987) and is the 3-D generalization of the 1-D elastodynamic homogenization scheme presented by Nemat-Nasser & Srivastava (2011). We show that for 3-D periodic composites the overall compliance (stiffness) tensor is hermitian, irrespective of whether the corresponding unit cell is geometrically or materially symmetric.Overall mass density is shown to be a tensor and, like the overall compliance tensor, always hermitian. The average strain and linear momentum tensors are, however, coupled and the coupling tensors are shown to be each others' hermitian transpose. Finally we present a numerical example of a 3-D periodic composite composed of elastic cubes periodically distributed in an elastic matrix. The presented results corroborate the predictions of the theoretical treatment.
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.
Excitation and control of multi-phase periodic waves in
Fominov, Yakov
the phase of the excited wave by the driver ("phase-locking") control the wave by varying parametersExcitation and control of multi-phase periodic waves in sine-Gordon equation Arkadiy Shagalovµcr U ()eff U ()eff Threshold condition for phase-locking: µ > µcr = 0.41 > cr = 3.28 3/2 0m 3
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.
Diffusive propagation of wave packets in a fluctuating periodic potential
Eman Hamza; Yang Kang; Jeffrey Schenker
2010-10-05T23:59:59.000Z
We consider the evolution of a tight binding wave packet propagating in a fluctuating periodic potential. If the fluctuations stem from a stationary Markov process satisfying certain technical criteria, we show that the square amplitude of the wave packet after diffusive rescaling converges to a superposition of solutions of a heat equation.
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
On the Survival of Short-Period Terrestrial Planets
Rosemary A. Mardling; D. N. C. Lin
2004-06-30T23:59:59.000Z
The currently feasible method of detection of Earth-mass planets is transit photometry, with detection probability decreasing with a planet's distance from the star. The existence or otherwise of short-period terrestrial planets will tell us much about the planet formation process, and such planets are likely to be detected first if they exist. Tidal forces are intense for short-period planets, and result in decay of the orbit on a timescale which depends on properties of the star as long as the orbit is circular. However, if an eccentric companion planet exists, orbital eccentricity ($e_i$) is induced and the decay timescale depends on properties of the short-period planet, reducing by a factor of order $10^5 e_i^2$ if it is terrestrial. Here we examine the influence companion planets have on the tidal and dynamical evolution of short-period planets with terrestrial structure, and show that the relativistic potential of the star is fundamental to their survival.
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
Colloidal Inks for Directed Assembly of 3-D Periodic Structures
Lewis, Jennifer
during assembly, which simultaneously facilitated bonding and shape retention of the deposited elements the desired 3-D periodicity, places the most stringent demands on ink design. Direct-write techniques- controlled viscoelastic response; that is, they must be able to flow through a deposition nozzle
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
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
infeasible to transmit sensor data over long distances, or in an underground system of ... the case of static sensors, their placement to best protect people has been ... function of the event dynamics and type of events: (1) What is the QoM of a ... a class of periodic coverage algorithms considering the travel time overhead.
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
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
Total Estimated Contract Cost: Performance Period Total Fee Paid
Office of Environmental Management (EM)
Fee Paid 127,390,991 Contract Number: Fee Available Contract Period: Contract Type: Cost Plus Award Fee 4,104,318,749 28,500,000 31,597,837 0 39,171,018 32,871,600 EM...
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
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.
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...
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
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
1-ID: Sector 1, Insertion Device Beamline
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A No. of Poles 72 Undulator Period 3.3 cm Device Length 2.4 m Minimum Gap 11 mm Downstream insertion device No. of Poles 72 Undulator Period 2.3 cm Device Length 2.4 m Minimum...
Periodic photometric variability of the brown dwarf Kelu-1
F. J. Clarke; C. G. Tinney; K. R. Covey
2002-01-10T23:59:59.000Z
We have detected a strong periodicity of 1.80+/-0.05 hours in photometric observations of the brown dwarf Kelu-1. The peak-to-peak amplitude of the variation is ~1.1% (11.9+/-0.8 mmag) in a 41nm wide filter centred on 857nm and including the dust/temperature sensitive TiO & CrH bands. We have identified two plausible causes of variability: surface features rotating into- and out-of-view and so modulating the light curve at the rotation period; or, elliposidal variability caused by an orbiting companion. In the first scenario, we combine the observed vsin(i) of Kelu-1 and standard model radius to determine that the axis of rotation is inclined at 65+/-12 degrees to the line of sight.
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...
Wave propagation in periodic networks of thin fibers
S. Molchanov; B. Vainberg
2009-08-02T23:59:59.000Z
We will discuss a one-dimensional approximation for the problem of wave propagation in networks of thin fibers. The main objective here is to describe the boundary (gluing) conditions at branching points of the limiting one-dimensional graph. The results will be applied to Mach-Zehnder interferometers on chips and to periodic chains of the interferometers. The latter allows us to find parameters which guarantee the transparency and slowing down of wave packets.
Spatially Dispersive Inhomogeneous Electromagnetic Media with Periodic Structure
Gratus, Jonathan
2015-01-01T23:59:59.000Z
Spatially dispersive (also known as non-local) electromagnetic media are considered where the parameters defining the permittivity relation vary periodically. Maxwell's equations give rise to a difference equation corresponding to the Floquet modes. A complete set of approximate solutions is calculated which are valid when the inhomogeneity is small. This is applied to inhomogeneous wire media. A new feature arises when considering spatially dispersive media, that is the existence of coupled modes.
A climatological analysis of the freeze period of Texas
Donahue, Christopher Alan
1991-01-01T23:59:59.000Z
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Synoptic Patterns Sample Calculations and Applications CONCLUSIONS AND RECOMMENDATIONS. . . 31 41 45 59 70 76 VI 81 APPENDIX Computer Programs 83 VITA 90 LIST OF TABLES Table Page 1 Periods of record for substations 17 2 Sample of data... of the freeze in parentheses. . . . . . . . . 64 16 Dates of 10% and 90% first and last freeze probabilities 75 tx LIST OF FIGURES Figure Page Map of the study area with the substation locations indicated . 2 Station history for Corsicana, Texas 16...
PARC Periodical: Volume 5, Issue 3 | 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeedingBiomass and BiofuelsOversightand SimulatedEQUILIBRIUM4,Periodical:
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
On 3D instabilities of 2D time-periodic flows - Department of ...
The Karman vortex street, the 2D periodically shedding wake of a circular cylinder, is the prototypical example. We shall consider this as well as a periodically ...
Properties of an axially periodic magnetic field in a betatron
Zvontsov, A.A.; Filinova, V.A.; Chakhlov, V.L.
1983-07-01T23:59:59.000Z
It is shown by solving an equation for the vector potential A (r, z) of the magnetic field that under appropriate conditions the focusing properties of a betatron magnetic field are periodic with respect to the z coordinate. Under these conditions there may be several equilibrium orbits lying in parallel planes z = 0, z = z/sub 01/ xxx, z = mz/sub 01/ in the accelerator. An equation is derived for the distance z/sub 01/ between the equilibrium orbit planes for a given orbit radius r/sub 0/ and field decay exponent n/sub 0/. The operation of such accelerators is described.
Light bullets in nonlinear periodically curved waveguide arrays
Matuszewski, Michal; Garanovich, Ivan L. [Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Sukhorukov, Andrey A. [Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Centre for Ultra-high Bandwidth Devices for Optical Systems (CUDOS), Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia)
2010-04-15T23:59:59.000Z
We predict that stable mobile spatiotemporal solitons can exist in arrays of periodically curved optical waveguides. We find two-dimensional light bullets in planar arrays with harmonic waveguide bending and three-dimensional bullets in square lattices with helical waveguide bending using variational formalism. Stability of the light-bullet solutions is confirmed by the direct numerical simulations which show that the light bullets can freely move across the curved arrays. This mobility property is a distinguishing characteristic compared to previously considered discrete light bullets which were trapped to a specific lattice site. These results suggest new possibilities for flexible spatiotemporal manipulation of optical pulses in photonic lattices.
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.
Holographic classification of Topological Insulators and its 8-fold periodicity
André LeClair; Denis Bernard
2012-05-16T23:59:59.000Z
Using generic properties of Clifford algebras in any spatial dimension, we explicitly classify Dirac hamiltonians with zero modes protected by the discrete symmetries of time-reversal, particle-hole symmetry, and chirality. Assuming the boundary states of topological insulators are Dirac fermions, we thereby holographically reproduce the Periodic Table of topological insulators found by Kitaev and Ryu. et. al, without using topological invariants nor K-theory. In addition we find candidate Z_2 topological insulators in classes AI, AII in dimensions 0,4 mod 8 and in classes C, D in dimensions 2,6 mod 8.
Dense periodic packings of tetrahedra with small repeating units
Yoav Kallus; Veit Elser; Simon Gravel
2010-03-19T23:59:59.000Z
We present a one-parameter family of periodic packings of regular tetrahedra, with the packing fraction $100/117\\approx0.8547$, that are simple in the sense that they are transitive and their repeating units involve only four tetrahedra. The construction of the packings was inspired from results of a numerical search that yielded a similar packing. We present an analytic construction of the packings and a description of their properties. We also present a transitive packing with a repeating unit of two tetrahedra and a packing fraction $\\frac{139+40\\sqrt{10}}{369}\\approx0.7194$.
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].
EIS-0391: Notice to Extend Scoping Period | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
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 DataDepartment of Energy Your Density Isn't Your Destiny:Revised FindingDepartment of Energy :to Extend Scoping Period EIS-0391: Notice
Tsallis Distribution Decorated With Log-Periodic Oscillation
Wilk, Grzegorz
2015-01-01T23:59:59.000Z
In many situations, in all branches of physics, one encounters power-like behavior of some variables which are best described by a Tsallis distribution characterized by a nonextensivity parameter $q$ and scale parameter $T$. However, there exist experimental results which can be described only by a Tsallis distributions which are additionally decorated by some log-periodic oscillating factor. We argue that such a factor can originate from allowing for a complex nonextensivity parameter $q$. The possible information conveyed by such an approach (like the occurrence of complex heat capacity, the notion of complex probability or complex multiplicative noise) will also be discussed.
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.
Periodic forcing of graphene as geometric ripples on its surface
Tridev Mishra; Tapomoy Guha Sarkar; Jayendra N. Bandyopadhyay
2014-10-27T23:59:59.000Z
We explore the possibility of using modulated high frequency periodic driving of mono-layer graphene to create effects of curved geometry. The low energy continuum limit of graphene is modeled using Dirac equation in (2+1) dimensions. We suggest that the modifications to the Dirac equation when written in a curved background space can also be induced by a suitable driving scheme. The time dependent system yields, in the approximate limit of high frequency pulsing, an effective time independent Hamiltonian that governs the time evolution, except for an initial and a final kick. We use a specific form of 4-phase pulsed forcing with suitably tuned choice of modulating operators to mimic the effects of weak metric perturbations and thereby effectively induce mild wrinkles on the surface. The strength of the perturbation is found to be directly related to omega^{-1} the time period of the driving field at the leading order. We apply the method to engineer some specific `nearly flat' metrics and we find that the imprint of curvilinear geometry modifies the band structure significantly. The emergence of band gap at the Dirac point is crucial in this regard. We suggest that this method shall be useful in studying the response of various properties of such materials to non-trivial geometry without requiring any actual physical deformations.
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...
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 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 (
ANL/APS/TB-3 Undulator A Characteristics and Specifications
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
at the closed gap of 1.15 cm, the first harmonic has an energy width of Ll 0.1 keY (Ei 4.2 keY) while the third harmonic has a width of 0.14 keY (E3 12.6 keY). When the...
HYBRID UNDULATORS AND WIGGLERS LS-18 S.H. Kim
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
than 1.5, it is seen that the decreasing rates of the peak brilliance with increasing harmonic numbers are rather slow. Because of considerable computing time for the spectral...
Dependence of Undulator Spectra on Viewing Slits S. H. Kim
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
magnetic field of By Bo sin (2ZAU)' may be expressed as (1) where v is the harmonic number of the radiated photon energy and gv(p,q) is given in LS-8.(1) In Eq. (1),...
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, ...
Feedback Control of the Sawtooth Period through Real Time Control of the Ion Cyclotron Resonance Frequency
Broader source: Energy.gov [DOE]
Energy Conservation Program for Consumer Products: Test Procedures for Furnaces and Boilers, Comment Period Extension
Aliev, Gazi N., E-mail: g.aliev@bath.ac.uk; Goller, Bernhard [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom)
2014-09-07T23:59:59.000Z
A one-dimensional Fibonacci phononic crystal and a distributed Bragg reflector were constructed from porous silicon. The structures had the same number of layers and similar acoustic impedance mismatch, and were electrochemically etched in highly boron doped silicon wafers. The thickness of the individual layers in the stacks was approximately 2??m. Both types of hypersonic band gap structure were studied by direct measurement of the transmittance of longitudinal acoustic waves in the 0.1–2.6?GHz range. Acoustic band gaps deeper than 50?dB were detected in both structures. The experimental results were compared with model calculations employing the transfer matrix method. The acoustic properties of periodic and quasi-periodic structures in which half-wave retarding bi-layers do not consist of two quarter-wave retarding layers are discussed. The strong correlation between width and depth of gaps in the transmission spectra is demonstrated. The dominant mechanisms of acoustic losses in porous multilayer structures are discussed. The elastic constants remain proportional over our range of porosity, and hence, the Grüneisen parameter is constant. This simplifies the expression for the porosity dependence of the Akhiezer damping.
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.
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.
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.
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...
Ratchet transport and periodic structures in parameter space
Alan Celestino; Cesar Manchein; Holokx A. Albuquerque; Marcus W. Beims
2011-11-06T23:59:59.000Z
Ratchet models are prominent candidates to describe the transport phenomenum in nature in the absence of external bias. This work analyzes the parameter space of a discrete ratchet model and gives direct connections between chaotic domains and a family of isoperiodic stable structures with the ratchet current. The isoperiodic structures appear along preferred direction in the parameter space giving a guide to follow the current, which usually increases inside the structures but is independent of the corresponding period. One of such structures has the shrimp-shaped form which is known to be an universal structure in the parameter space of dissipative systems. Currents in parameter space provide a direct measure of the momentum asymmetry of the multistable and chaotic attractors times the size of the corresponding basin of attraction. Transport structures are shown to exist in the parameter space of the Langevin equation with an external oscillating force.
Periodic forcing of a 555-IC based hysteretic oscillator
Moises Santillan
2014-08-12T23:59:59.000Z
In this work we designed and developed a master-slave electronic oscillatory system (based on the 555-timer IC working in the astable mode), and investigated its dynamic behavior regarding synchronization. For that purpose we measured the circulation number corresponding to the phase-locking rhythm achieved in a large set of values of the normalized forcing period (NFP) and of the coupling strength between the master and the slave oscillators. In particular we were interested in the system behavior in the strong-coupling limit, because such problem has not been extensively studied from an experimental perspective. Our results indicate the existence of a degenerate codimension-2 bifurcation point at NFP=1:2, where all the phase-locking regions converge in the very strong coupling limit. These findings were corroborated by a mathematical model we developed to that end.
Transverse commensurability effect for vortices on periodic pinning arrays
Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
Using computer simulations, we demonstrate a type of commensurability that occurs for vortices moving longitudinally through periodic pinning arrays in the presence of an additional transverse driving force. As a function of vortex density, there is a series of broad maxima in the transverse critical depinning force that do not fall at the matching fields where the number of vortices equals an integer multiple of the number of pinning sites. The commensurability effects are associated with dynamical states in which evenly spaced structures consisting of one or more moving rows of vortices form between rows of pinning sites. Remarkably, the critical transverse depinning force can be more than an order of magnitude larger than the longitudinal depinning force.
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.
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).
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.
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.
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.
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.
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.
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
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...
Wave propagation and instabilities in monolithic and periodically structured elastomeric materials; revised manuscript received 3 October 2008; published 14 November 2008 Wave propagation in elastomeric states can influence wave propagation and hence interpretation of data. In the case of periodically
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
A STUDY OF THE SHORTEST-PERIOD PLANETS FOUND WITH KEPLER
Kotson, Michael C.
We present the results of a survey aimed at discovering and studying transiting planets with orbital periods shorter than one day (ultra-short-period, or USP, planets), using data from the Kepler spacecraft. We computed ...
PERIODIC SOLUTIONS WITH NONCONSTANT SIGN IN ABEL EQUATIONS OF THE SECOND KIND
PolitÃ¨cnica de Catalunya, Universitat
PERIODIC SOLUTIONS WITH NONCONSTANT SIGN IN ABEL EQUATIONS OF THE SECOND KIND JOSEP M. OLM, XAVIER, is equivalent. Key words and phrases. Abel differential equations, periodic solutions. 1 #12;2 JOSEP M. OLM
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
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.
RF properties of periodic accelerating structures for linear colliders
Wang, J.W.
1989-07-01T23:59:59.000Z
With the advent of the SLAC electron-positron linear collider (SLC) in the 100 GeV center-of-mass energy range, research and development work on even higher energy machines of this type has started in several laboratories in the United States, Europe, the Soviet Union and Japan. These linear colliders appear to provide the only promising approach to studying e/sup /plus//e/sup /minus// physics at center-of-mass energies approaching 1 TeV. This thesis concerns itself with the study of radio frequency properties of periodic accelerating structures for linear colliders and their interaction with bunched beams. The topics that have been investigated are: experimental measurements of the energy loss of single bunches to longitudinal modes in two types of structures, using an equivalent signal on a coaxial wire to simulate the beam; a method of canceling the energy spread created within a single bunch by longitudinal wakefields, through appropriate shaping of the longitudinal charge distribution of the bunch; derivation of the complete transient beam-loading equation for a train of bunches passing through a constant-gradient accelerator section, with application to the calculation and minimization of multi-bunch energy spread; detailed study of field emission and radio frequency breakdown in disk-loaded structures at S-, C- and X-band frequencies under extremely high-gradient conditions, with special attention to thermal effects, radiation, sparking, emission of gases, surface damage through explosive emission and its possible control through RF-gas processing. 53 refs., 49 figs., 9 tabs.
Direct Energy Conversion Fission Reactor for the period December 1, 1999 through February 29, 2000
Brown, L.C.
2000-03-20T23:59:59.000Z
OAK B135 Direct Energy Conversion Fission Reactor for the period December 1, 1999 through February 29, 2000
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
Fabrication of 200 nm period nanomagnet arrays using interference lithography and a negative resist
Murphy, Thomas E.
period array of holes in a positive resist and electrodeposited magnetic nickel and cobalt pillars.4 We
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
Margaliot, Michael
, the biological system must entrain or phase-lock to the periodic excitation. Entrainment is also important entrain or phase-lock to the periodic excitation. In other words, in response to a periodic excitation in biological systems (sometimes called phase locking [2]) and, more generally, biological oscillators
Glass, Leon
Entrainment and termination of reentrant wave propagation in a periodically stimulated ring periodic stimulation of a class of cardiac arrhythmias caused by reentrant wave propagation in the human wave of circulation. In analogy with earlier results found from the periodic stimulation
Year Budget Period 1 5/1/2012 4/30/2013
Kay, Mark A.
/1/2014 Â 4/30/2015 Year Budget Period 4 5/1/2015 date of the budget period funded by the FY15 funds Ã? The Final Financial of the end date of the last budget period funded by the FY14 funds Ã? Departments
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.
A Low-Charge, Hard X-Ray FEL Driven with an X-band Injector and Accelerator
Sun, Yipeng; Adolphsen, Chris; Limborg-Deprey, Cecile; Raubenheimer, Tor; Wu, Juhao; /SLAC
2012-02-17T23:59:59.000Z
After the successful operation of FLASH (Free-Electron Laser in Hamburg) and LCLS (Linac Coherent Light Source), soft and hard X-ray Free Electron Lasers (FELs) are being built, designed or proposed at many accelerator laboratories. Acceleration employing lower frequency RF cavities, ranging from L-band to C-band, is usually adopted in these designs. In the first stage bunch compression, higher-frequency harmonic RF system is employed to linearize the beam's longitudinal phase space, which is nonlinearly chirped during the lower frequency RF acceleration process. In this paper, a hard X-ray FEL design using an all X-band accelerator at 11.424 GHz (from photo-cathode RF gun to linac end) is presented, without the assistance of any harmonic RF linearization. It achieves LCLS-like performance at low charge using X-band linac drivers, which is more versatile, efficient and compact than ones using S-band or C-band rf technology. It employs initially 42 microns long (RMS), low charge (10 pC) electron bunches from an X-band photoinjector. An overall bunch compression ratio of roughly 100 times is proposed in a two stage bunch compressor system. The start-to-end macro-particle 3-D simulation employing several computer codes is presented in this paper, where space charge, wakefields, incoherent and coherent synchrotron radiation (ISR and CSR) effects are included. Employing an undulator with a short period of 1.5 cm, a Genesis FEL simulation shows successful lasing at a wavelength of 0.15 nm with a pulse length of 2 fs and a power saturation length as short as 20 meters, which is equivalent to LCLS low charge mode. Its overall length of both accelerators and undulators is 180 meters (much shorter than the effective LCLS overall length of 1230 meters, including an accelerator length of 1100 meters and an undulator length of 130 meters), which makes it possible to be built in places where only limited space is available.
Low-Charge, Hard X-Ray Free Electron Laser Driven with an X-Band Injector and Accelerator
Sun, Yipeng; Adolphsen, Chris; Limborg-Deprey, Cecile; Raubenheimer, Tor; Wu, Juhao; /SLAC
2012-04-17T23:59:59.000Z
After the successful operation of the Free Electron Laser in Hamburg (FLASH) and the Linac Coherent Light Source (LCLS), soft and hard x-ray free electron lasers (FELs) are being built, designed, or proposed at many accelerator laboratories. Acceleration employing lower frequency rf cavities, ranging from L-band to C-band, is usually adopted in these designs. In the first stage bunch compression, higher-frequency harmonic rf system is employed to linearize the beam's longitudinal phase space, which is nonlinearly chirped during the lower frequency rf acceleration process. In this paper, a hard x-ray FEL design using an all X-band accelerator at 11.424 GHz (from photocathode rf gun to linac end) is presented, without the assistance of any harmonic rf linearization. It achieves LCLS-like performance at low charge using X-band linac drivers, which is more versatile, efficient, and compact than ones using S-band or C-band rf technology. It employs initially 42 microns long (rms), low-charge (10 pC) electron bunches from an X-band photoinjector. An overall bunch compression ratio of roughly 100 times is proposed in a two stage bunch compressor system. The start-to-end macroparticle 3D simulation employing several computer codes is presented in this paper, where space charge, wakefields, and incoherent and coherent synchrotron radiation effects are included. Employing an undulator with a short period of 1.5 cm, a Genesis FEL simulation shows successful lasing at a wavelength of 0.15 nm with a pulse length of 2 fs and a power saturation length as short as 20 meters, which is equivalent to LCLS low-charge mode. Its overall length of both accelerators and undulators is 180 meters (much shorter than the effective LCLS overall length of 1230 meters, including an accelerator length of 1100 meters and an undulator length of 130 meters), which makes it possible to be built in places where only limited space is available.
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.
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...
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 ...
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...
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...
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...
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
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
Approximations to wave propagation through doubly-periodic arrays of scatterers
Approximations to wave propagation through doubly-periodic arrays of scatterers P. Mc Abstract The propagation of waves through a doubly-periodic array of identical rigid scatterers of matched asymptotic expansions is used to obtain the dispersion relation corresponding to wave propagation
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
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
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
Covariation of coastal water temperature and microbial pollution at interannual to tidal periods
Winant, Clinton D.
Covariation of coastal water temperature and microbial pollution at interannual to tidal periods, California, USA Daniel B. Lluch-Cota Centro de Investigaciones Biologicas del Noroeste, La Paz, Mexico-period cooling are coincident with elevated levels of microbial pollution in the surf zone. This relationship can
Instability inside a rotating gas cylinder subject to axial periodic strain Y. Duguet,a
Paris-Sud XI, UniversitÃ© de
of viscous flow inside a closed circular cylinder rotating about its axis, periodically compressed by meansInstability inside a rotating gas cylinder subject to axial periodic strain Y. Duguet,a J. F. Scott are known to support inertial oscillations whose frequencies are less than twice the basic rotation rate.1
Commensurability effects induced by a periodic array of nanoscale anti-dots in Nb superconductor
Metlushko, Vitali
Commensurability effects induced by a periodic array of nanoscale anti-dots in Nb superconductor A. PACS: 74.25.Ha; 74.76.)w Keywords: Nanostructures; Anti-dots; Commensurability 1. Introduction atomic layers on periodical substrate [5], magnetic bubble arrays [6] and the magnetically induced Wigner
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
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
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
ON THE EXISTENCE OF STEADY PERIODIC CAPILLARY-GRAVITY STRATIFIED WATER WAVES
points for steady water waves. The condition which ensures the lack of stagnation points for 1991ON THE EXISTENCE OF STEADY PERIODIC CAPILLARY-GRAVITY STRATIFIED WATER WAVES DAVID HENRY AND BOGDANVASILE MATIOC Abstract. We prove the existence of small steady periodic capillary-gravity water waves
Ungerleider, Leslie G.
Program Director/Principal Investigator (Last, First, Middle): DETAILED BUDGET FOR INITIAL BUDGET SUBTOTAL DIRECT COSTS FOR INITIAL BUDGET PERIOD (Item 7a, Face Page) $ CONSORTIUM/CONTRACTUAL COSTS FACILITIES AND ADMINISTRATIVE COSTS TOTAL DIRECT COSTS FOR INITIAL BUDGET PERIOD $ PHS 398 (Rev. 6/09) Page
Baker, Chris I.
Program Director/Principal Investigator (Last, First, Middle): DETAILED BUDGET FOR INITIAL BUDGET SUBTOTAL DIRECT COSTS FOR INITIAL BUDGET PERIOD (Item 7a, Face Page) $ CONSORTIUM/CONTRACTUAL COSTS FACILITIES AND ADMINISTRATIVE COSTS TOTAL DIRECT COSTS FOR INITIAL BUDGET PERIOD $ Page Form Page 4 PHS 398
An inverse free electron laser accelerator experiment
Wernick, I.; Marshall, T.C.
1992-01-01T23:59:59.000Z
A free electron laser was configured as an autoaccelerator to test the principle of accelerating electrons by stimulated absorption of radiation ([lambda] = 1.65mm) by an electron beam (750kV) traversing an undulator. Radiation is produced in the first section of a constant period undulator (1[sub w1] = 1.43cm) and then absorbed ([approximately] 40%) in a second undulator, having a tapered period (1[sub w2] = 1.8 [minus] 2.25cm), which results in the acceleration of a subgroup ([approximately] 9%) of electrons to [approximately] 1MeV.
An inverse free electron laser accelerator experiment
Wernick, I.; Marshall, T.C.
1992-12-31T23:59:59.000Z
A free electron laser was configured as an autoaccelerator to test the principle of accelerating electrons by stimulated absorption of radiation ({lambda} = 1.65mm) by an electron beam (750kV) traversing an undulator. Radiation is produced in the first section of a constant period undulator (1{sub w1} = 1.43cm) and then absorbed ({approximately} 40%) in a second undulator, having a tapered period (1{sub w2} = 1.8 {minus} 2.25cm), which results in the acceleration of a subgroup ({approximately} 9%) of electrons to {approximately} 1MeV.
Propagation of travelling waves in sub-excitable systems driven by noise and periodic forcing
Fen-Ni Si; Quan-Xing Liu; Jin-Zhong Zhang; Lu-Qun Zhou
2007-11-23T23:59:59.000Z
It has been reported that traveling waves propagate periodically and stably in sub-excitable systems driven by noise [Phys. Rev. Lett. \\textbf{88}, 138301 (2002)]. As a further investigation, here we observe different types of traveling waves under different noises and periodic forces, using a simplified Oregonator model. Depending on different noises and periodic forces, we have observed different types of wave propagation (or their disappearance). Moreover, the reversal phenomena are observed in this system based on the numerical experiments in the one-dimensional space. As an explanation, we regard it as the effect of periodic forces. Thus, we give qualitative explanations to how reversal phenomena stably appear, which seem to arise from the mixing function of the periodic force and the noise. And the output period and three velocities (the normal, the positive and the negative) of the travelling waves are defined and their relationship with the periodic forces, along with the types of waves, are also studied in sub-excitable system under a fixed noise intensity.
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.
Office of Environmental Management (EM)
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33Frequently Asked QuestionsDepartmentGas and| Department of Energy WindowProgram |ImproperFee
Diaz, H.F. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Research Labs.; Hughes, M.K. [Arizona Univ., Tucson, AZ (United States). Lab. of Tree-Ring Research
1992-12-31T23:59:59.000Z
The workshop will focus on climatic variations during the Medieval Warm Period or Little Climatic Optimum. The nominal time interval assigned to this period is AD 900--1300, but climate information available during the century or two preceding and following this episode is welcome. The aims of the workshop will be to: examine the available evidence for the existence of this episode; assess the spatial and temporal synchronicity of the climatic signals; discuss possible forcing mechanisms; and identify areas and paleoenvironmental records where additional research efforts are needed to improve our knowledge of this period. This document consists of abstracts of eighteen papers presented at the meeting.
Nemat-Nasser, Sia
Homogenized dynamic constitutive relation for Bloch-wave propagation in periodic composites composites has been made only very recently. Here we discuss the explicit form of the effective dynamic properties of composites with tailored microstructure necessitates a systematic homogenization procedure
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
Dental analysis of Classic period population variability in the Maya area
Scherer, Andrew Kenneth
2005-02-17T23:59:59.000Z
In this dissertation I examine population history and structure in the Maya area during the Classic period (A.D. 250-900). Within the Maya area, archaeologists have identified regional variation in material culture between ...
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....
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.
Skinner, L.; McCave, I. N.; Carter, L.; Fallon, S.; Scrivner, A. E.; Primeau, F.
2014-12-15T23:59:59.000Z
It has been proposed that the ventilation of the deep Pacific carbon pool was not significantly reduced during the last glacial period, posing a problem for canonical theories of glacial–interglacial CO2 change. However, using radiocarbon dates...
The effect of disorder on the wave propagation in one-dimensional periodic optical systems
Yuri A. Godin; Stanislav Molchanov; Boris Vainberg
2011-10-18T23:59:59.000Z
The influence of disorder on the transmission through periodic waveguides is studied. Using a canonical form of the transfer matrix we investigate dependence of the Lyapunov exponent $\\gamma$ on the frequency $\
Simulation of adiabatic thermal beams in a periodic solenoidal magnetic focusing field
Barton, T. J.
Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [ K.?R. Samokhvalova, J. Zhou and C. Chen ...
Periodic orbit bifurcations as an ionization mechanism: The bichromatically driven hydrogen atom
S. Huang; C. Chandre; T. Uzer
2007-12-17T23:59:59.000Z
We investigate the multiphoton ionization of hydrogen driven by a strong bichromatic microwave field. In a regime where classical and quantum simulations agree, periodic orbit analysis captures the mechanism: Through the linear stability of periodic orbits we match qualitatively the variation of experimental ionization rates with control parameters such as the amplitudes of the two modes of the field or their relative phases. Moreover, we discuss an empirical formula which reproduces quantum simulations to a high degree of accuracy. This quantitative agreement shows the mechanism by which short periodic orbits organize the dynamics in multiphoton ionization. We also analyze the effect of longer pulse durations. Finally we compare our results with those based on the peak amplitude rule. Both qualitative and quantitative analyses are implemented for different mode locked fields. In parameter space, the localization of the period doubling and halving allows one to predict the set of parameters (amplitudes and phase lag) where ionization occurs.
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 ...
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 ...
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
Fejer, Martin M.
- conversion interactions.2 5 There have been several reports that periodically poled lithium niobate (PPLN s is a parameter that depends on the properties of the host crystal, donors, and traps and nd is the dark
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 ...
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 ...
Semiclassical analysis for a Schrodinger operator with a U(2) artificial gauge: the periodic case
Paris-Sud XI, UniversitÃ© de
: semiclassical asymptotic, spectrum, eigenvalues, Schrodinger, periodic potential, BKW method, width of the first Preliminary: the artificial gauge model 3 3 Proof of Theorem 2.1 5 4 Asymptotic of the first band 6 5 B.K.W
Semiclassical analysis for a Schrodinger operator with a U(2) artificial gauge: the periodic case
Paris-Sud XI, UniversitÃ© de
: semiclassical asymptotic, spectrum, eigenvalues, Schrodinger, periodic potential, BKW method, width of the first Preliminary: the artificial gauge model 3 3 Proof of Theorem 2.1 5 4 Asymptotic of the first band 7 5 B.K.W
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.
Ergodic theory and visualization. II. Harmonic mesochronic plots visualize (quasi)periodic sets
Zoran Levnaji?; Igor Mezi?
2014-07-26T23:59:59.000Z
We present a new method of analysis of measure-preserving dynamical systems, based on frequency analysis and ergodic theory, which extends our earlier work [1]. Our method employs the novel concept of harmonic time average [2], and is realized as a computational algorithms for visualization of periodic and quasi-periodic sets or arbitrary periodicity in the phase space. Besides identifying all periodic sets, our method is useful in detecting chaotic phase space regions with a good precision. The range of method's applicability is illustrated using well-known Chirikov standard map, while its full potential is presented by studying higher-dimensional measure-preserving systems, in particular Froeschl\\'e map and extended standard map.
Public Comment Period for Portsmouth Site D&D and Waste Disposition...
Office of Environmental Management (EM)
2014 8:00AM EST to March 11, 2015 5:00PM EDT Public Comment Period for the Process Buildings and Complex Facilities Decontamination and Decommissioning and Site-Wide Waste...
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...
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.
Spatial Periodic Forcing Can Displace Patterns It Is Intended to Control
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Mau, Yair; Hagberg, Aric; Meron, Ehud
2012-07-01T23:59:59.000Z
Spatial periodic forcing of pattern-forming systems is an important, but lightly studied, method of controlling patterns. It can be used to control the amplitude and wave number of one-dimensional periodic patterns, to stabilize unstable patterns, and to induce them below instability onset. We show that, although in one spatial dimension the forcing acts to reinforce the patterns, in two dimensions it acts to destabilize or displace them by inducing two-dimensional rectangular and oblique patterns.
Effect of the hepatoma growth period on host plasma and liver lipid concentrations
Matocha, Martha Frances
1979-01-01T23:59:59.000Z
EFFECT OF THE HEPATOMA GROWTH PERIOD ON HOST PLASMA AND LIVER LIPID CONCENTRATIONS A Thesis by MARTHA FRANCES MATOCHA Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE August 1979 Niajor Sub ect: Biochem. 'stry EFFECT OF THE HEPATOMA GROWTH PERIOD ON HOST PLASMA AND LIVER LIPID CONCENTRATIONS A Thesis MARTHA FRANCES MATOCHA Approved as to style and content by: (Chairman of Committee) (Mern...
An improved correlation method for determining the period of a torsion pendulum
Luo Jie; Wang Dianhong [Faculty of Mechanical and Electronic Information, China University of Geosciences, Wuhan 430074 (China)
2008-09-15T23:59:59.000Z
Considering variation of environment temperature and unhomogeneity of background gravitational field, an improved correlation method was proposed to determine the variational period of a torsion pendulum with high precision. The result of processing experimental data shows that the uncertainty of determining the period with this method has been improved about twofolds than traditional correlation method, which is significant for the determination of gravitational constant with time-of-swing method.
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.
Development of Advanced Concept for Shortening Construction Period of ABWR Plant
Hiroshi Ijichi; Toshio Yamashita; Masahiro Tsutagawa; Hiroya Mori [Toshiba Corporation (Japan); Nobuaki Ooshima; Jun Miura [Hitachi Ltd. (Japan); Minoru Kanechika [Kajima Corporation (Japan); Nobuaki Miura [Shimizu Corporation (Japan)
2002-07-01T23:59:59.000Z
Construction of a nuclear power plant (NPP) requires a very long period because of large amount of construction materials and many issues for negotiation among multiple sections. Shortening the construction period advances the date of return on an investment, and can also result in reduced construction cost. Therefore, the study of this subject has a very high priority for utilities. We achieved a construction period of 37 months from the first concrete work to fuel loading (F/L) (51.5 months from the inspection of the foundation (I/F) to the start of commercial operation (C/O)) at the Kashiwazaki-Kariwa NPPs No. 6 and 7 (KK-6/7), which are the first ABWR plants in the world. At TEPCO's next plant, we think that a construction period of less than 36 months (45 months from I/F to C/O) can be realized based on conventional methods such as early start of equipment installation and blocking of equipment to be brought in advance. Furthermore, we are studying the feasibility of a 21.5-month construction period (30 months from I/F to C/O) with advanced ideas and methods. The important concepts for a 21.5-month construction period are adoption of a new building structure that is the steel plate reinforced concrete (SC) structure and promotion of extensive modularization of equipment and building structure. With introducing these new concepts, we are planning the master schedule (M/S) and finding solutions to conflicts in the schedule of area release from building construction work to equipment installation work (schedule-conflicts.) In this report, we present the shortest construction period and an effective method to put it into practice for the conventional general arrangement (GA) of ABWR. In the future, we will continue the study on the improvement of building configuration and arrangements, and make clear of the concept for large composite modules of building structures and equipment. (authors)
THE SPECTROSCOPIC SIGNATURE OF QUASI-PERIODIC UPFLOWS IN ACTIVE REGION TIMESERIES
Tian Hui; McIntosh, Scott W. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 8037 (United States); De Pontieu, Bart, E-mail: htian@ucar.edu, E-mail: mscott@ucar.edu, E-mail: bdp@lmsal.com [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States)
2011-02-01T23:59:59.000Z
Quasi-periodic propagating disturbances are frequently observed in coronal intensity image sequences. These disturbances have historically been interpreted as being the signature of slow-mode magnetoacoustic waves propagating into the corona. The detailed analysis of Hinode EUV Imaging Spectrometer (EIS) timeseries observations of an active region (known to contain propagating disturbances) shows strongly correlated, quasi-periodic, oscillations in intensity, Doppler shift, and line width. No frequency doubling is visible in the latter. The enhancements in the moments of the line profile are generally accompanied by a faint, quasi-periodically occurring, excess emission at {approx}100 km s{sup -1} in the blue wing of coronal emission lines. The correspondence of quasi-periodic excess wing emission and the moments of the line profile indicates that repetitive high-velocity upflows are responsible for the oscillatory behavior observed. Furthermore, we show that the same quasi-periodic upflows can be directly identified in a simultaneous image sequence obtained by the Hinode X-Ray Telescope. These results are consistent with the recent assertion of De Pontieu and McIntosh that the wave interpretation of the data is not unique. Indeed, given that several instances are seen to propagate along the direction of the EIS slit that clearly shows in-phase, quasi-periodic variations of intensity, velocity, width (without frequency doubling), and blue wing enhanced emission, this data set would appear to provide a compelling example that upflows are more likely to be the main cause of the quasi-periodicities observed here, as such correspondences are hard to reconcile in the wave paradigm.
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.
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.
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...
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.
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.
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
Othman, Mohamed; Capolino, Filippo
2014-01-01T23:59:59.000Z
We show the existence of a new regime of operation for travelling wave tubes (TWTs) composed of slow-wave periodic structures that support two or more electromagnetic modes, with at least two synchronized with an electron beam. The interaction between the slow-wave structure and an electron beam is quantified using a multi transmission line approach (MTL) and transfer matrix analysis leading to the identification of modes with complex Bloch wavenumber. In particular, we report a new operation condition for TWTs based on an electron beam synchronous to two modes exhibiting a degeneracy condition near a band edge in a MTL slow-wave periodic structure. We show a phenomenological change in the band structure of periodic TWT where we observe at least two growing modal cooperating solutions as opposed to a uniform MTL interacting with an electron beam where there is strictly only one growing mode solution.
On the Stability of the 421-day Periodicity in A0538-66
Katherine E. McGowan; Phil A. Charles
2002-11-01T23:59:59.000Z
In this paper we analyse 70 years of archival Harvard and Schmidt plate data of the 16.6 d Be X-ray binary A0538-66 in order to search for the presence of the long-term period of 420.82 +/- 0.79 d found in MACHO photometry (Alcock et al. 2001). We find evidence for a long-term period of 421.29 +/- 0.95 d in the archival data, and examine its stability. We also combine the archival and MACHO datasets in order to improve the accuracy of the orbital period determination, using a cycle-counting analysis to refine its value to 16.6460 +/- 0.0004 d. We also test the model proposed in our previous paper (Alcock et al. 2001) with observations documented in the literature for A0538-66 from 1980-1995, constraining the system inclination to be i > 74.9 +/- 6.5 deg.
Broadband asymmetric acoustic transmission by a plate with quasi-periodic surface ridges
Li, Chunhui; Ke, Manzhu, E-mail: mzke@whu.edu.cn; Ye, Yangtao; Xu, Shengjun; Qiu, Chunyin; Liu, Zhengyou [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)
2014-07-14T23:59:59.000Z
In this paper, an acoustic system with broadband asymmetric transmission is designed and fabricated, which consists of a water-immersed aluminum plate engraved with quasi-periodically-patterned ridges on single surface. It demonstrates that when the acoustic waves are launched into the system from the structured side, they can couple into the Lamb modes in the plate efficiently and attain a high transmission; on the contrary, when the waves are incident from the opposite flat side, the coupling is weak, and the transmission is low. Superior to systems with periodic patterning, this quasi-periodically-patterned system has a broad working frequency range due to the collective contributions from the multiple diffractions specific to the structure.
Controlled motion of Janus particles in periodically phase-separating binary fluids
Takeaki Araki; Shintaro Fukai
2015-04-03T23:59:59.000Z
We numerically investigate the propelled motions of a Janus particle in a periodically phase-separating binary fluid mixture. In this study, the surface of the particle tail prefers one of the binary fluid components and the particle head is neutral in the wettability. During the demixing period, the more wettable phase is selectively adsorbed to the particle tail. Growths of the adsorbed domains induce the hydrodynamic flow in the vicinity of the particle tail, and this asymmetric pumping flow drives the particle toward the particle head. During the mixing period, the particle motion almost ceases because the mixing primarily occurs via diffusion and the resulting hydrodynamic flow is negligibly small. Repeating this cycle unboundedly moves the Janus particle toward the head. The dependencies of the composition and the repeat frequency on the particle motion are discussed.
X-ray Variability and Period Determinations in the Eclipsing Polar DP Leo
C. R. Robinson; F. A. Cordova
1994-08-15T23:59:59.000Z
An analysis of ROSAT observations for the eclipsing magnetic cataclysmic binary DP Leo provides constraints on the origin, size, temperature, variability and structure of the soft X-ray emission region on the surface of the white dwarf. These data, when combined with prior observations, show a progression of approximately 2 degrees per year in the impact position of the accretion stream onto the white dwarf. One explanation for the observed drift in stream position is that a magnetic activity cycle on the secondary produces orbital period oscillations. These oscillations result in an orbital period which cycles above and below the rotational period of the nearly synchronous white dwarf. The accretion stream and X-ray emission regions are modeled to fit the observational data. A distance to the system is also calculated. [An erroneous value for the cyclotron luminosity, included in an earlier paper version of the preprint, is corrected here.
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.
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.
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.
Long-Period Objects in the Extrasolar Planetary Systems 47 UMa and 14 Her
Robert A. Wittenmyer; Michael Endl; William D. Cochran
2006-09-05T23:59:59.000Z
The possible existence of additional long-period planetary-mass objects in the extrasolar planetary systems 47 UMa and 14 Her is investigated. We combine all available radial-velocity data on these stars, spanning up to 18 years. For the 47 UMa system, we show that while a second planet improves the fit to all available data, there is still substantial ambiguity as to the orbital parameters of the proposed planetary companion 47 UMa c. We also present new observations which clearly support a long-period companion in the 14 Her system. With a period of 6906+/-70 days, 14 Her c may be in a 4:1 resonance with the inner planet. We also present revised orbital solutions for 7 previously known planets incorporating recent additional data obtained with the 2.7m Harlan J. Smith Telescope at McDonald Observatory.
BoseEinstein condensates in spatially periodic potentials Kirstine BergSrensen 1 and Klaus Mlmer 2
Berg-SÃ¸rensen, Kirstine
BoseÂEinstein condensates in spatially periodic potentials Kirstine BergÂSÃ¸rensen 1 and Klaus theoretically the properties of a BoseÂEinstein condensate located in a spatially periodic potential. The excitations of the condensate are obtained from linear equations involving the periodic potential
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
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.
Propagation of matter wave solitons in periodic and random nonlinear potentials
Fatkhulla Kh. Abdullaev; Josselin Garnier
2005-11-10T23:59:59.000Z
We study the motion of bright matter wave solitons in nonlinear potentials, produced by periodic or random spatial variations of the atomic scattering length. We obtain analytical results for the soliton motion, the radiation of matter wave, and the radiative soliton decay in such configurations of the Bose-Einstein condensate. The stable regimes of propagation are analyzed. The results are in remarkable agreement with the numerical simulations of the Gross-Pitaevskii equation with periodic or random spatial variations of the mean field interactions.
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.
Getting More For Your Money: Identifying and Confirming Long-Period Planets with Kepler
Jennifer C. Yee; B. Scott Gaudi
2008-07-16T23:59:59.000Z
Kepler will monitor enough stars that it is likely to detect single transits of planets with periods longer than the mission lifetime. We show that by combining the Kepler photometry of such transits with precise radial velocity (RV) observations taken over ~3 months, and assuming circular orbits, it is possible to estimate the periods of these transiting planets to better than 20% (for planets with radii greater than that of Neptune) and the masses to within a factor of 2 (for planet masses m_p > M_Jup). We also explore the effects of eccentricity on our estimates of these uncertainties.
Orbital period derivative of a binary system using an exact orbital energy equation
Vikram H. Zaveri
2014-11-07T23:59:59.000Z
It is proposed that the equations of motion in periodic relativity which yielded major predictions of general relativity without utilizing Riemannian geometry and geodesic trajectories are exact in nature and can be applied to pulsars and inspiraling compact binaries for analyzing orbital period derivative and two polarization gravitational wave forms. Exactness of these equations eliminates the need for higher order xPN corrections to the orbital energy part of the balance equation. This is mainly due to the introduction of dynamic WEP which states that the gravitational mass is equal to the relativistic mass.
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...
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.
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.
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.
McGaugh, Emily Cozette
1996-01-01T23:59:59.000Z
(1883) GOOD 3~0, 690 3, 442, 784 3, 602+33 4, 367, 766 HOUSEKEEPING (1885) 4, 437, 978 4, 673, 416 REDBOOK 1, 980, 153 2, 048, 407 2, 288, 170 2, 689, 510 2, 808, 729 2, 994, 059 (1903) READER'S DIGEST N/A 10, 000, 000 11, 024, 410 12, 184, 516 12.... Civil Rights, Transition. SUMMARY AND CONCLUSIONS. S ummary. Conclusions. BIBLIOGRAPHY. VITA . . Page tv v 1 2 3 7 13 15 19 20 23 26 26 26 32 37 LIST OF TABLES TABLES 1 Black Periodicals Circulation. 2 White Periodicals...
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...
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...
MULTI-PERIOD CAPACITY PLANNING FOR INTEGRATED PRODUCT-PROCESS DESIGN
Saitou, Kazuhiro "Kazu"
the quality of the finished products and minimize the total production cost dur- ing the periods. The product the quality of the 415 #12;finished products and minimizes the total cost of production. The product quality and operating costs of a production facility and the quality of finished prod- ucts. Given forecasted market
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
Real-time Scheduling of periodic tasks in a monoprocessor system with rechargeable energy storage
Paris-Sud XI, UniversitÃ© 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
A MEDIEVAL WARM PERIOD l)13 C RECORD FROM THE GAURA CU MUSCA CAVE, SW ROMANIA
Forray, Ferenc
A MEDIEVAL WARM PERIOD l)13 C RECORD FROM THE GAURA CU MUSCA CAVE, SW ROMANIA Bogdan P. ONAC1 Â· 2, Romania (2) School of Geosciences, University of South Florida, 4202 E. Fowler Ave., NES 107, Tampa, FL and Romania. B. Geological map of the region {modified fromlancu et al., 1995). The mapof the Gaura cu Musca
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 ...
Proceedings Published 2007 by the American Chemical Society Double Direct Templating of Periodically
Braun, Paul
of Periodically Nanostructured Inorganic Hollow Microspheres Paul V. Braun, Alejandro Wolosiuk, Dongyeon Son, Dara, and Frederick Seitz Materials Research Laboratory, Urbana, IL 61801 INTRODUCTION Hollow capsules are both technologically and scientifically interesting. `Smart' nano and micro containers could lead to structures
Double Direct Templating of Periodically Nanostructured ZnS Hollow Microspheres
Braun, Paul
Double Direct Templating of Periodically Nanostructured ZnS Hollow Microspheres Alejandro Wolosiuk 61801 Received July 22, 2005; E-mail: pbraun@uiuc.edu Hollow capsules are both technologically and scientifically interesting. "Smart" nano- and microcontainers could lead new catalysts, structures
RESEARCH COUNCILS' INDIVIDUAL MERIT PROMOTION SCHEME INDIVIDUAL MERIT PROMOTION PERIODIC REVIEW
Brierley, Andrew
GUIDANCE NOTES Please read these guidance notes carefully before completing the form. You may also wish in the development and exploitation of technologies 6. Provide a CV that summarises your career to date; include that have had an impact on your career progression; for example, periods of maternity leave, part
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
SEARCHES FOR PERIODIC NEUTRINO EMISSION FROM BINARY SYSTEMS WITH 22 AND 40 STRINGS OF ICECUBE
Abbasi, R.; Aguilar, J. A.; Andeen, K.; Baker, M. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Abdou, Y. [Department of Physics and Astronomy, University of Gent, B-9000 Gent (Belgium); Abu-Zayyad, T. [Department of Physics, University of Wisconsin, River Falls, WI 54022 (United States); Ackermann, M.; Bazo Alba, J. L. [DESY, D-15735 Zeuthen (Germany); Adams, J. [Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Ahlers, M. [Department of Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Allen, M. M. [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Altmann, D. [III. Physikalisches Institut, RWTH Aachen University, D-52056 Aachen (Germany); Auffenberg, J. [Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany); Bai, X. [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Barwick, S. W. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Bay, R. [Department of Physics, University of California, Berkeley, CA 94720 (United States); Beattie, K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Beatty, J. J. [Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Bechet, S. [Universite Libre de Bruxelles, Science Faculty CP230, B-1050 Brussels (Belgium); Becker, J. K. [Fakultaet fuer Physik and Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Collaboration: IceCube Collaboration; and others
2012-04-01T23:59:59.000Z
In this paper, we present the results of searches for periodic neutrino emission from a catalog of binary systems. Such modulation, observed in the photon flux, would be caused by the geometry of these systems. In the analysis, the period is fixed by these photon observations, while the phase and duration of the neutrino emission are treated as free parameters to be fit with the data. If the emission occurs during {approx}20% or less of the total period, this analysis achieves better sensitivity than a time-integrated analysis. We use the IceCube data taken from 2007 May 31 to 2008 April 5 with its 22 string configuration and from 2008 April 5 to 2009 May 20 with its 40 string configuration. No evidence for neutrino emission is found, with the strongest excess occurring for Cygnus X-3 at 2.1{sigma} significance after accounting for trials. Neutrino flux upper limits for both periodic and time-integrated emission are provided.
What hides behind extended periods of youth unemployment in Bosnia and Herzegovina?
Paris-Sud XI, UniversitÃ© de
What hides behind extended periods of youth unemployment in Bosnia and Herzegovina? Evidence from This paper provides the first empirical analysis on youth unemployment duration in Bosnia and ongoing economic and political reforms, the old economic structure and patterns of em- ployment in Bosnia
QUANTUM ENERGY EXPECTATION IN PERIODIC TIME-DEPENDENT HAMILTONIANS VIA GREEN
QUANTUM ENERGY EXPECTATION IN PERIODIC TIME-DEPENDENT HAMILTONIANS VIA GREEN FUNCTIONS CÂ´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
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{sub 2}H{sub 5}OH) and water (H{sub 2}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.
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.
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).
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 ...
Day, Nathan Allan
1994-01-01T23:59:59.000Z
of inclusions with both periodic and random arrangements. Transducer sets having center frequencies of 0.25 MHz to 2.25 MHz were used for the tests. The rigid-body resonance of the particles was observed. The frequency of this resonance was found to be dependent...
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.
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
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
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 ...
Periodic orbit analysis of a system with continuous symmetry - a tutorial
Nazmi Burak Budanur; Daniel Borrero-Echeverry; Predrag Cvitanovi?
2015-02-06T23:59:59.000Z
Dynamical systems with translational or rotational symmetry arise frequently in studies of spatially extended physical systems, such as Navier-Stokes flows on periodic domains. In these cases, it is natural to express the state of the fluid in terms of a Fourier series truncated to a finite number of modes. Here, we study a 4-dimensional two-mode SO(2)-equivariant model of this type, the smallest possible truncation that retains the symmetry but is high-dimensional enough to allow for chaotic dynamics. A crucial step in the analysis of such a system is symmetry reduction. We use the model to illustrate different symmetry-reduction techniques. Its relative equilibria are conveniently determined by rewriting the dynamics in terms of a symmetry-invariant polynomial basis. However, for the analysis of its chaotic dynamics, the `method of slices', which is applicable to very high-dimensional problems, is preferable. We show that a Poincar\\'e section taken on the `slice' can be used to further reduce this flow to what is for all practical purposes a unimodal map. This enables us to systematically determine all relative periodic orbits and their symbolic dynamics up to any desired period. We then present cycle averaging formulas adequate for systems with continuous symmetry and use them to compute dynamical averages using relative periodic orbits. The convergence of such computations is discussed.
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.
Is the apparent period-doubling in Blazhko stars actually an illusion?
Bryant, Paul H
2015-01-01T23:59:59.000Z
It is known that the light curves of many Blazhko stars exhibit intervals in which successive pulsation maxima alternate between two levels in a way that is characteristic of period-doubling. In addition, hydrodynamical models of these stars have clearly demonstrated period-doubling bifurcations. As a result, it is now generally accepted that these stars do indeed exhibit period-doubling. Here we present strong evidence that this assumption is incorrect. The alternating peak heights likely result from the presence of one or more near-resonant modes which appear in the stellar spectra and are significantly offset from 3/2 times the fundamental frequency. A previous explanation for the presence of these peaks is shown to be inadequate. The phase-slip of the dominant near-resonant peak in RR Lyr is shown to be fully correlated with the parity of the observed alternations, providing further strong evidence that the process is nonresonant and cannot be characterized as period-doubling. The dominant near-resonant p...
Post Common Envelope Binaries from SDSS - III. Seven new orbital periods
Rebassa-Mansergas, A; Schreiber, M R; Southworth, J; Schwope, A D; Gomez-Moran, A Nebot; Aungwerojwit, A; Rodríguez-Gil, P; Karamanavis, V; Krumpe, M; Tremou, E; Schwarz, R; Staude, A; Vogel, J
2008-01-01T23:59:59.000Z
We present follow-up spectroscopy and photometry of 11 post common envelope binary (PCEB) candidates identified from multiple Sloan Digital Sky Survey (SDSS) spectroscopy in an earlier paper. Radial velocity measurements using the \\Lines{Na}{I}{8183.27,8194.81} absorption doublet were performed for nine of these systems and provided measurements of six orbital periods in the range $\\Porb= 2.7-17.4$ h. Three PCEB candidates did not show significant radial velocity variations in the follow-up data, and we discuss the implications for the use of SDSS spectroscopy alone to identify PCEBs. Differential photometry confirmed one of our spectroscopic orbital periods and provided one additional \\Porb measurement. Binary parameters are estimated for the seven objects for which we have measured the orbital period and the radial velocity amplitude of the low-mass companion star, $K_\\mathrm{sec}$. So far, we have published nine SDSS PCEBs orbital periods, all of them $\\Porb1$ day, and that during the common envelope phase...
Post Common Envelope Binaries from SDSS - III. Seven new orbital periods
A. Rebassa-Mansergas; B. T. Gaensicke; M. R. Schreiber; J. Southworth; A. D. Schwope; A. Nebot Gomez-Moran; A. Aungwerojwit; P. Rodriguez-Gil; V. Karamanavis; M. Krumpe; E. Tremou; R. Schwarz; A. Staude; J. Vogel
2008-08-15T23:59:59.000Z
We present follow-up spectroscopy and photometry of 11 post common envelope binary (PCEB) candidates identified from multiple Sloan Digital Sky Survey (SDSS) spectroscopy in an earlier paper. Radial velocity measurements using the \\Lines{Na}{I}{8183.27,8194.81} absorption doublet were performed for nine of these systems and provided measurements of six orbital periods in the range $\\Porb= 2.7-17.4$ h. Three PCEB candidates did not show significant radial velocity variations in the follow-up data, and we discuss the implications for the use of SDSS spectroscopy alone to identify PCEBs. Differential photometry confirmed one of our spectroscopic orbital periods and provided one additional \\Porb measurement. Binary parameters are estimated for the seven objects for which we have measured the orbital period and the radial velocity amplitude of the low-mass companion star, $K_\\mathrm{sec}$. So far, we have published nine SDSS PCEBs orbital periods, all of them $\\Porb1$ day, and that during the common envelope phase the orbital energy of the binary star is maybe less efficiently used to expell the envelope than frequently assumed.
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.
Wolkowicz, Gail S. K.
, the single-species growth model, has a threshold between global extinction and uniform persistenceDifferential and Integral Equations Volume...., Number....., pp. N-SPECIES COMPETITION is proved and then applied to models of single-species growth and n-species competition in a periodically
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)
Weekly Security Incident Log Period of May 14 -May 20, 2012
Weekly Security Incident Log Period of May 14 - May 20, 2012 Incident No. Reported Date Building-000955 PARKING GARAGE - ARBORETUM LANE (PS2) Mech\\Electrical Security responded to a report that an automotive York Security responded to a report of an unknown male causing a disturbance in the food court
West, David Edward
2014-12-12T23:59:59.000Z
Micron-sized, spanwise-periodic, discrete roughness elements (DREs) were applied to and tested on a 30° swept-wing model in order to study their effects on boundary-layer transition in flight where stationary crossflow waves are the dominant...
Periodically Controlled Hybrid Systems Verifying A Controller for An Autonomous Vehicle
Murray, Richard M.
Periodically Controlled Hybrid Systems Verifying A Controller for An Autonomous Vehicle Tichakorn Hybrid Au- tomata (PCHA) for describing a class of hybrid control systems. In a PCHA, control actions of the planner-controller subsystem of an autonomous ground vehicle, and in deriving geometric properties
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
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
Parrondo, Juan M.R.
Reversible ratchets as Brownian particles in an adiabatically changing periodic potential Juan M. R of particles is induced without any energy consumption. These cycles can be called reversible ratchets called ratch- ets, since they are somehow inspired by the discussion in Ref. 16 of a ratchet working
Jonckheere, Thibaut
Chaotic Hamiltonian ratchets for pulsed periodic double-well potentials: Classical correlations and the ratchet current N. A. C. Hutchings,1 M. R. Isherwood,1 T. Jonckheere,2 and T. S. Monteiro1 1 Department, ratchet currents, and time scales of a new ratchet in a fully chaotic Hamiltonian system, introduced
Ratchet Effects Induced by Terahertz Radiation in Heterostructures with a Lateral Periodic Potential
Ganichev, Sergey
Ratchet Effects Induced by Terahertz Radiation in Heterostructures with a Lateral Periodic of the Seebeck ratchet effect. The effect is measured in semiconductor heterostructures with a one ratchet effect, we observe a photon helicity dependent response and propose a microscopic mechanism
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
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
Wright, Angela Shanna
2004-01-01T23:59:59.000Z
/Lo), linseed oil (Hi/Lo), low (Lo/Mod) or high (Lo/Hi) menhaden fish oil. Plasma was collected on days 0, 3, 7, 14, 28, 42, and 56 of gestation, days 10 and 28 of lactation, and days 4, 10, 16, 28, 70, and 84 of the neonatal period. Electrophoresis was run...
Cornell-Bahir Dar University Master's Program Report for the period November 2007 to February 2011
Walter, M.Todd
1 Cornell-Bahir Dar University Master's Program Report for the period November 2007 to February 2011 The Cornell University/Bahir Dar University (CU/BDU) Master's of Professional Studies (MPS. In January 2010 another 14 students came to the Bahir Dar campus. This is the first graduate degree program
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
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.
Frictional powders: Ratcheting under periodic strain in 3D , C. T. David2
Luding, Stefan
and Coulomb friction. In the simplest case visco-elastic rules can be imposed at each contact, differentFrictional powders: Ratcheting under periodic strain in 3D S. Luding1 , C. T. David2 , R. Garcia of friction leads to a transition from ratcheting to shake-down, i.e., the accumulation of strain stops
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...
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
Globally synchronous ice core volcanic tracers and abrupt cooling during the last glacial period
Price, P. Buford
Globally synchronous ice core volcanic tracers and abrupt cooling during the last glacial period R ash layers determined by remote optical borehole logging and core assays. We find that the Antarctic. These globally coincident volcanics were associated with abrupt cooling, often simultaneous with onsets or sudden
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
EXTENDING THE CONCEPTS OF RETURN PERIOD AND RETURN LEVEL TO A CHANGING CLIMATE
Katz, Richard
-Stationarity in Extremes (3) Risk Communication under Stationarity (4) Risk Communication under Climate Change (5;#12;(4) Risk Communication Under Climate Change Â· One Approach -- "Effective" return level Permit "return levelEXTENDING THE CONCEPTS OF RETURN PERIOD AND RETURN LEVEL TO A CHANGING CLIMATE Rick Katz Institute
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.
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 ...
Development/Plasticity/Repair A Refractory Period for Rejuvenating GABAergic Synaptic
Gruner, Daniel S.
Development/Plasticity/Repair A Refractory Period for Rejuvenating GABAergic Synaptic Transmission and Ocular Dominance Plasticity with Dark Exposure Shiyong Huang,1* Yu Gu,2* Elizabeth M. Quinlan,2 Dark exposure initiated in adulthood reactivates robust ocular dominance plasticity in the visual
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
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
Ruoxi Xiang; Michael Small
2014-06-18T23:59:59.000Z
In this work, the topologies of networks constructed from time series from an underlying system undergo a period doubling cascade have been explored by means of the prevalence of different motifs using an efficient computational motif detection algorithm. By doing this we adopt a refinement based on the $k$ nearest neighbor recurrence-based network has been proposed. We demonstrate that the refinement of network construction together with the study of prevalence of different motifs allows a full explosion of the evolving period doubling cascade route to chaos in both discrete and continuous dynamical systems. Further, this links the phase space time series topologies to the corresponding network topologies, and thus helps to understand the empirical "superfamily" phenomenon, as shown by Xu.
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.
The BVRI Light Curves And Period Analysis Of The Beta Lyrae System XX Leonis
P. Zasche; M. Wolf; P. Svoboda
2007-11-19T23:59:59.000Z
The contact eclipsing binary system XX Leonis (P = 0.97 days, sp A8) has been analysed using the PHOEBE programme, based on the Wilson Devinney code. The BVRI light curves were obtained during spring 2006 using the 20-cm telescope and ST-7 CCD detector. The effective temperature of the primary component determined from the photometric analysis is T=(7889+/-61)K, the inclination of the orbit is i=(89.98+/-2.45)deg and the photometric mass ratio q=(0.41+/-0.01). Also the third body hypothesis was suggested, based on the period analysis using 57 minimum times and resulting the period of the third body p3= (52.96+/-0.01)yr, amplitude A=(0.057+/-0.029)d and eccentricity e=(0.79+/-0.08) which gives the minimum mass m3,min=(3.6+/-0.8)M_sun.
Periodic Optical Outbursts from the Be/Neutron Star Binary AX J0049.4-7323
A. P. Cowley; P. C. Schmidtke
2003-11-17T23:59:59.000Z
The optical light curve of the Be/neutron star binary AX J0049.4-7323 has been investigated using data from the MACHO and OGLE-II projects. This X-ray source, whose neutron star has a very slow rotation rate (P_pulse=755.5 sec), shows optical outbursts every 394 days. The regularity of these outbursts suggests that their recurrence time is the orbital period of the system. During the outbursts the system brightens and becomes slightly redder. A possible interpretation is that a portion of the equatorial disk is excited as the neutron star passes through it during periastron passage. In the intervals between outbursts the light curve shows 11-day quasi-periodic varability which may be associated with the rotation of the Be star's extended disk.
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.
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.
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.
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.
Stephen P. Shipman
2014-04-24T23:59:59.000Z
It is known that, if a locally perturbed periodic self-adjoint operator on a combinatorial or quantum graph admits an eigenvalue embedded in the continuous spectrum, then the associated eigenfunction is compactly supported--that is, if the Fermi surface is irreducible, which occurs generically in dimension two or higher. This article constructs a class of operators whose Fermi surface is reducible for all energies by coupling several periodic systems. The components of the Fermi surface correspond to decoupled spaces of hybrid states, and in certain frequency bands, some components contribute oscillatory hybrid states (corresponding to spectrum) and other components contribute only exponential ones. This separation allows a localized defect to suppress the oscillatory (radiation) modes and retain the evanescent ones, thereby leading to embedded eigenvalues whose associated eigenfunctions decay exponentially but are not compactly supported.
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.
The Long Period AM Her-like Cataclysmic Variable RXJ051541+0104.6
F. M. Walter; S. J. Wolk; N. R. Adams
1994-08-29T23:59:59.000Z
We report the discovery of a new catacysmic variable system, RXJ051541+0104.6. The optical spectrum has a blue continuum with superposed H~I and He~I and II emission lines. The soft X-ray spectrum is well fit with a 50~eV black body. The X-ray and optical data are suggestive of an AM~Herculis system. The X-ray light curve shows extreme variability on timescales of seconds, and suggests an orbital period of order 8~hours, nearly twice that of the longest catalogued AM~Her period. When bright, the X-ray light curve breaks up into a series of discrete bursts, which may be due to accretion of dense blobs of material of about 10$^{17}$~gm mass.
Trends in Aqueous Hydration Across the 4f Period Assessed by Reliable Computational Methods
Kuta, Jadwiga; Clark, Aurora E.
2010-09-06T23:59:59.000Z
The geometric and electronic structures, as well as the thermodynamic properties of trivalent lanthanide hydrates {Ln(H?O)?,? ³? and Ln(H?O)?,?(H?O)??,?? ³?, Ln = La – Lu} have been examined using unrestricted density functional theory (UDFT), unrestricted M€oller-Plesset perturbation theory (UMP2), and multiconfigurational self-consistent field methods (MCSCF). While Ln-hydrates with 2-5 unpaired f-electrons have some multiconfigurational character, the correlation energy lies within 5-7 kcal/mol across the period and for varying coordination numbers. As such DFT yields structural parameters and thermodynamic data quite close to experimental values. Both UDFT and UMP2 predict free energies of water addition to the Ln(H?O)? ³? species to become less favorable across the period; however, it is a non-linear function of the surface charge density of the ion. UDFT further predicts that the symmetry of the metal-water bond lengths is sensitive to the specific f-electron configuration, presumably because of repulsive interactions between filled f-orbitals and water lone-pairs. Within the Ln(H?O)?,?(H?O)??,?? ³?clusters, interactions between solvation shells overrides this orbital effect, increasing the accuracy of the geometric parameters and calculated vibrational frequencies. Calculated atomic charges indicate that the water ligands each donate 0.1 to 0.2 electrons to the Ln(III) metals, with increasing electron donation across the period. Significant polarization and charge transfer between solvation shells is also observed. The relationship between empirical effective charges and calculated atomic charges is discussed with suggestions for reconciling the trends across the period.
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.
Dental analysis of Classic period population variability in the Maya area
Scherer, Andrew Kenneth
2005-02-17T23:59:59.000Z
collected dental nonmetric and metric traits on 977 skeletons, from 18 Classic period sites, representing seven different archaeological zones. I corrected the data for intraobserver error. For the dental nonmetric data, I developed a Maya-specific trait.... I analyzed the dental nonmetric and metric datasets with both univariate and multivariate tests. I found, with a log likelihood ratio, that 50% of the nonmetric traits exhibited statistically significant differences between Maya sites. I...
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.
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.
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.
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...
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.
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.
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".
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.
Worthington, Josiah Wistar
1966-01-01T23:59:59.000Z
of afterripening to chilling requirement of' parent V. SUMMARY AND CONCLUSIONS 20 26 29 LITERATURE CITED APPENDIX 34 Seed hydration as affected by soaking period Seed germination as influenced by seed hydration during afterripening 35 Germination of.... Influence of stratification time on germi- nation of S-37 and Okinawa peach seeds Page 22 LIST OF FIGURES 1. Seed hydration a. influenced by soaking Page 16 2. Afterripening effectiveness as influenced by pre- soaking seeds 17 3. Germination...
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.
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.
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.
PLANET HUNTERS: ASSESSING THE KEPLER INVENTORY OF SHORT-PERIOD PLANETS
Schwamb, Megan E. [Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520 (United States); Lintott, Chris J.; Lynn, Stuart; Smith, Arfon M.; Simpson, Robert J. [Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Fischer, Debra A.; Giguere, Matthew J.; Brewer, John M. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Parrish, Michael [Adler Planetarium, 1300 S. Lake Shore Drive, Chicago, IL 60605 (United States); Schawinski, Kevin, E-mail: megan.schwamb@yale.edu [Department of Physics, Yale University, New Haven, CT 06511 (United States)
2012-08-01T23:59:59.000Z
We present the results from a search of data from the first 33.5 days of the Kepler science mission (Quarter 1) for exoplanet transits by the Planet Hunters citizen science project. Planet Hunters enlists members of the general public to visually identify transits in the publicly released Kepler light curves via the World Wide Web. Over 24,000 volunteers reviewed the Kepler Quarter 1 data set. We examine the abundance of {>=}2 R{sub Circled-Plus} planets on short-period (<15 days) orbits based on Planet Hunters detections. We present these results along with an analysis of the detection efficiency of human classifiers to identify planetary transits including a comparison to the Kepler inventory of planet candidates. Although performance drops rapidly for smaller radii, {>=}4 R{sub Circled-Plus} Planet Hunters {>=}85% efficient at identifying transit signals for planets with periods less than 15 days for the Kepler sample of target stars. Our high efficiency rate for simulated transits along with recovery of the majority of Kepler {>=}4 R{sub Circled-Plus} planets suggests that the Kepler inventory of {>=}4 R{sub Circled-Plus} short-period planets is nearly complete.
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.
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...
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...