673 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Modulation"

open access

Photoluminescence Studies of Lateral Composition Modulated Short-Period AlAs/InAs Superlattices

We present low temperature photoluminescence data for a series of spontaneous lateral composition modulation in (AlAs){sub m}/(InAs){sub n} short period superlattices on InP with differing average lattice constants, i.e., varying global strain. The low temperature photoluminescence peak energies were found to be much lower than the corresponding energy expected for the equivalent In{sub x}Al{sub 1{minus}x}As alloy. The bandgap energy reductions are found to approach 500 meV and this reduction i… more

Date: January 4, 1999

Creator: Ahrenkiel, S. P.; Follstaedt, D. M.; Jones, E. D.; Lee, S. R.; Mascarenhas, A.; Mirecki-Millunchick, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Relativistically Self-Channeled Femtosecond Terawatt Lasers for High-Field Physics and X-Ray Generation

Optical channeling or refractive guiding processes involving the nonlinear interaction of intense femtosecond optical pulses with matter in the self-focussing regime has created exciting opportunities for next-generation laser plasma-based x-ray sources and directed energy applications. This fundamentally new form of extended paraxial electromagnetic propagation in nonlinear dispersive media such as underdense plasma is attributed to the interplay between normal optical diffraction and intensit… more

Date: January 1, 1999

Creator: Borisov, A. B.; Boyer, K.; Cameron, S. M.; Luk, T. S.; McPherson, A.; Nelson, T. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

Haiku

This short work was composed using a tuning system of the harmonic series of three fundamental pitches. The FM sounds were produced using a Yamaka TX81Z with articulation points from an Emulator II sample of a shakuhachi.

Access: Restricted to UNT Community Members. Login required if off-campus.

Date: 1987

Duration: 5 minutes

Creator: Harris, Ross, 1945-

Item Type: Sound

Partner: UNT Music Library

open access

Calibration of the modulation transfer function of surface profilometers with binary pseudo-random test standards: expanding the application range

A modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays [Proc. SPIE 7077-7 (2007), Opt. Eng. 47, 073602 (2008)] has been proven to be an effective MTF calibration method for a number of interferometric microscopes and a scatterometer [Nucl. Instr. and Meth. A616, 172 (2010)]. Here we report on a further expansion of the application range of the method. We describe the MTF calibration of a 6 inch phase shifting Fizeau interferometer. Beyond… more

Date: March 14, 2011

Creator: Yashchuk, Valeriy V.; Anderson, Erik H.; Barber, Samuel K.; Bouet, Nathalie; Cambie, Rossana; Conley, Raymond et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Complexity as Aging Non-Poisson Renewal Processes

The search for a satisfactory model for complexity, meant as an intermediate condition between total order and total disorder, is still subject of debate in the scientific community. In this dissertation the emergence of non-Poisson renewal processes in several complex systems is investigated. After reviewing the basics of renewal theory, another popular approach to complexity, called modulation, is introduced. I show how these two different approaches, given a suitable choice of the parameter … more

Date: May 2007

Creator: Bianco, Simone

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

An Innovative High-Temperature High-Pressure Measurement While Drilling (MWD) Tool

Measurement while drilling (MWD) tools specified to 150 C (302 F) that provide wellbore surveys, real-time inclination, and natural gamma ray detection are a commodity item in the oilfield services industry. MWD tools specified to 175 C (347 F) that routinely demonstrate highly reliable operation are available from only a few service companies. Commercial MWD tools that reliably operate to 200 C (392 F) for extended periods of time and offer features like real-time gamma ray, retrievability, an… more

Date: June 1, 2007

Creator: Boling, Brian

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

High Spectral Resolution X-ray Observation of Magnetic CVs: EX Hya

In magnetic cataclysmic variables (CVs) the primary is a highly magnetized white dwarf (WD) whose field controls the accretion flow close to the WD, leading to a shock and accretion column that radiate chiefly in X-rays. We present preliminary results from a 500 ks Chandra HETG observation of the brightest magnetic CV EX Hya. From the observational dataset we are able to measure the temperature and density at different points of the cooling accretion column using sensitive line ratios. We also … more

Date: April 7, 2008

Creator: Luna, G; Brickhouse, N S & Mauche, C W

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design and Evaluation of a Virtual Quadrant Receiver for 4-ary Pulse Position Modulation/Optical Code Division Multiple Access (4-ary PPM/O-CDMA)

M-ary pulse position modulation (M-ary PPM) is an alternative to on-off-keying (OOK) that transmits multiple bits as a single symbol occupying a frame of M slots. PPM does not require thresholding as in OOK signaling, instead performing a comparison test among all slots in a frame to make the slot decision. Combining PPM with optical code division multiple access (PPM/O-CDMA) adds the benefit of supporting multiple concurrent, asynchronous bursty PPM users. While the advantages of PPM/O-CDMA ar… more

Date: December 29, 2006

Creator: Mendez, A J; Hernandez, V J; Gagliardi, R M & Bennett, C V

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Proposal of An Experiment on Bunch Length Modulation in DAFNE

Obtaining very short bunches is an issue especially for colliders but also for CSR sources. The modulation of the bunch length in a strong rf focusing regime had been proposed, corresponding to a high value of the synchrotron tune. A ring structure where the function R56 along the ring oscillates between large positive and negative values will produce bunch length modulation. The synchrotron frequency can be tuned both by the rf power and by the integral of the function R56, up to the limit of … more

Date: January 20, 2006

Creator: Biscari, C.; Alesini, D.; Benedetti, G.; Biagini, M. E.; Boni, R.; Boscolo, M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Gridded Electron Guns and Modulation of Intense Beams

Gridded guns are useful for producing modulated electron beams. This modulation is generally limited to simple gating of the beam, but may be used to apply structure to the beam pulse shape. In intense beams, this structure spawns space charge waves whose dynamics depend in part on the relative strengths of the velocity and density variations which comprise the initial current modulation. In this paper, we calculate the strengths of beam current and velocity modulation produced in a gridded ele… more

Date: May 2, 2006

Creator: Harris, J R & O'Shea, P G

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Chromaticity Measurements Using Phase Modulated RF and Vector Signal Analyzers

Chromaticity measurements are usually done by changing the energy of the beam by a known amount and measuring the change in betatron tune with a spectrum analyzer. The energy change is done by adjusting the RF frequency. The change in RF frequency is made large enough so that the change in betatron tune can be seen. If synchrotron motion is present in the beam, then measuring the change in betatron tune can be difficult. This note will outline a method to measure the change in betatron tune by … more

Date: February 16, 2001

Creator: McGinnis, Dave

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Design of the Second-Generation ILC Marx Modulator

SLAC National Accelerator Laboratory (SLAC) has initiated a program to design and build a Marx-topology modulator to produce a relatively compact, low-cost, high availability klystron modulator for the International Linear Collider (ILC). Building upon the success of the P1 Marx, the SLAC P2 Marx is a second-generation modulator whose design further emphasizes the qualities of modularity and high-availability. This paper outlines highlights of this design and presents single-cell performance da… more

Date: September 14, 2010

Creator: Kemp, M. A.; Benwell, A.; Burkhart, C.; Larsen, R.; MacNair, D.; Nguyen, M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

On the Theory of the Modulation Instability in Optical Fibre Amplifiers

The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW radiation break-up and growth of multiple pulses. This can be both a detrimental effect limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model and the r… more

Date: May 10, 2010

Creator: Turitsyn, S K; Rubenchik, A M & Fedoruk, M P

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Magnetic Recorder for Nuclear Pulse Application. Period Covered: October 6, 1959 to December 5, 1959

Data on analog magnetic tape charactcristics are presented along with results from conventional and modulator playback system operational tests. Theoretical considerations imply that the modulator head should be loss sensitive to short term variations in record and playback tape speed. It is also pointed out that although a tape recorder operating at 7.5 in./sec has only 12 kcs bandwidth for sinusoidal wave forms. the record and play-back amplifiers for pulse recording can operate with other ba… more

Date: December 14, 1959

Creator: Burgwald, G. M. & Norton, R. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

QUAD FAMILY CENTERING.

It is well known that beam position monitors (BPM) utilizing signals from pickup electrodes (PUE) provide good resolution and relative accuracy. The absolute accuracy (i.e. position of the orbit in the vacuum chamber) is not very good due to the various reasons. To overcome the limitation it was suggested to use magnetic centers of quadrupoles for the calibration of the BPM [1]. The proposed method provides accuracy better then 200 microns for centering of the beam position monitors using modul… more

Date: November 1, 2005

Creator: PINAYEV, I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A D-moduli problem?

No Description Available.

Date: January 20, 2000

Creator: Gaillard, Mary K. & Giedt, Joel

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

THE GENERATION OF 400 MW RF PULSES AT X-BAND USING RESONANT DELAY LINES

We present theory and experimental data for a resonant-delay-line pulse-compression system. The system is fed by two high power klystrons at X-band. The output power is four times bigger than the input power. The system produces flat-top output pulses. The system uses evacuated room-temperature copper delay lines as a means of storing energy. These lines achieved a quality factor greater than 4.3 x 10{sup 5}, with total losses due to external components measured at 4%. We compare theory with ex… more

Date: March 8, 1999

Creator: Tantawi, Sami

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

NOTE ON A CLASS OF AMPLITUDE MODULATION DETECTORS.

No Description Available.

Date: January 1, 1964

Creator: Washburn, B. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Limits on spin-dependent wimp-nucleon interactions from the cryogenic dark matter search

The Cryogenic Dark Matter Search (CDMS) is an experiment to detect weakly interacting massive particles (WIMPs) based on their interactions with Ge and Si nuclei. We report the results of an analysis of data from the first two runs of CDMS at the Soudan Underground Laboratory in terms of spin-dependent WIMP-nucleon interactions on {sup 73}Ge and {sup 29}Si. These data exclude new regions of spin-dependent WIMP-nucleon interaction parameter space, including regions relevant to spin-dependent int… more

Date: September 1, 2005

Creator: Akerib, D. S.; Armel-Funkhouser, M. S.; Attisha, M. J.; Bailey, C. N.; Baudis, L.; Bauer, Daniel A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Solid-State Modulator R&D at LLNL

The Beam Research Program at Lawrence Livermore National Laboratory (LLNL) has been developing solid-state modulators for accelerator applications for several years. These modulators are based on inductive adder circuit topology and have demonstrated great versatility with regard to pulse width and pulse repetition rate while maintaining fast pulse rise and fall times. These modulators are also capable of being scaled to higher output voltage and power levels. An explanation of the circuit oper… more

Date: December 4, 2002

Creator: Cook, E. G.; Allen, F. V.; Anaya, E. M.; Gower, E. J.; Hawkins, S. A.; Hickman, B. C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Performance of actinic EUVL mask imaging using a zoneplatemicroscope

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a dual-mode, scanning and imaging extreme-ultraviolet (EUV) microscope designed for pre-commercial EUV mask research. Dramatic improvements in image quality have been made by the replacement of several critical optical elements, and the introduction of scanning illumination to improve uniformity and contrast. We report high quality actinic EUV mask imaging with resolutions as low as 100-nm half-pitch, (20-nm, 5x wafer equivalent size), and … more

Date: August 20, 2007

Creator: Goldberg, Kenneth A.; Naulleau, Patrick P.; Barty, Anton; Rekawa,Senajith B.; Kemp, Charles D.; Gunion, Robert F. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modulational effects in accelerators

We discuss effects of field modulations in accelerators, specifically those that can be used for operational beam diagnostics and beam halo control. In transverse beam dynamics, combined effects of nonlinear resonances and tune modulations influence diffusion rates with applied tune modulation has been demonstrated. In the longitudinal domain, applied RF phase and voltage modulations provide mechanisms for parasitic halo transport, useful in slow crystal extraction. Experimental experiences wit… more

Date: December 1, 1997

Creator: Satogata, T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Hadron beam-beam diffusion in 2.5-D

The standard analysis of modulational diffusion for general nonlinearities is qualitatively summarized, and compared to the particular case of a beam-beam simulation with two kicks per turn, plus tune modulation. A simulation with realistic Tevatron parameters shows amplitude growth over long timescales of order 10{sup 4} synchrotron periods. The simulated amplitude growth is qualitatively similar to the predictions of modulational diffusion, showing large discrete steps in the evolution speed … more

Date: July 1, 1999

Creator: Satogata, T. & Peggs, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Pulse transformer R and D for NLC klystron pulse modulator

The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a r… more

Date: July 1, 1997

Creator: Akemoto, M.; Gold, S.; Krasnykh, A. & Koontz, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department