Sample records for fm chirp waveforms

  1. Generating nonlinear FM chirp waveforms for radar.

    SciTech Connect

    Doerry, Armin Walter

    2006-09-01

    Nonlinear FM waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM waveform with equivalent sidelobe filtering. This report presents design and implementation techniques for Nonlinear FM waveforms.

  2. SAR processing with non-linear FM chirp waveforms.

    SciTech Connect

    Doerry, Armin Walter

    2006-12-01

    Nonlinear FM (NLFM) waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM (LFM) waveform with equivalent sidelobe filtering. This report presents details of processing NLFM waveforms in both range and Doppler dimensions, with special emphasis on compensating intra-pulse Doppler, often cited as a weakness of NLFM waveforms.

  3. Multiplexed chirp waveform synthesizer

    DOEpatents

    Dudley, Peter A.; Tise, Bert L.

    2003-09-02

    A synthesizer for generating a desired chirp signal has M parallel channels, where M is an integer greater than 1, each channel including a chirp waveform synthesizer generating at an output a portion of a digital representation of the desired chirp signal; and a multiplexer for multiplexing the M outputs to create a digital representation of the desired chirp signal. Preferably, each channel receives input information that is a function of information representing the desired chirp signal.

  4. Simplified Homodyne Detection for FM Chirped Lidar

    E-print Network

    Adany, Peter

    2007-12-14

    ................................................................4 CHAPTER 2 – RADAR AND LIDAR TOPICS....................................................................6 2.1 REVIEW OF EXISTING LIDAR SYSTEMS..............................................................6 Geoscience Laser Altimeter System (GLAS..............................................................................18 2.3 PULSE COMPRESSION........................................................................................19 A Basic Pulse Compression Method................................................................20 Linear FM Chirp with Analog Mixing...

  5. High Resolution Pulse Compression Imaging Using Super Resolution FM-Chirp Correlation Method (SCM)

    NASA Astrophysics Data System (ADS)

    Fujiwara, M.; Okubo, K.; Tagawa, N.

    This study addresses the issue of the super-resolution pulse compression technique (PCT) for ultrasound imaging. Time resolution of multiple ultrasonic echoes using the FM-Chirp PCT is limited by the bandwidth of the sweep-frequency. That is, the resolution depends on the sharpness of auto-correlation function. We propose the Super resolution FM-Chirp correlation Method (SCM) and evaluate its performance. This method is based on the multiple signal classification (MUSIC) algorithm. Our simulations were made for the model assuming multiple signals reflected from some scatterers. We confirmed that SCM detects time delay of complicated reflected signals successfully with high resolution.

  6. Generation of a widely tunable linearly chirped microwave waveform based on spectral filtering and unbalanced dispersion.

    PubMed

    Zhang, Hao; Zou, Weiwen; Chen, Jianping

    2015-03-15

    We propose a method to generate a widely tunable linearly chirped microwave waveform based on spectral filtering and unbalanced dispersion. Heterodyne beating between two differently dispersed optical pulses in a photodetector produces the linearly chirped microwave waveform. Desired waveforms with flexible and independent control of the center frequency and sweep bandwidth can be obtained by simply tuning two optical filters. Simulation and experimental investigations are carried out, and the results are in good agreement. The measured microwave waveform has ?5.2-ns pulse duration and ?64-GHz sweep bandwidth, corresponding to a time-bandwidth product of ?166.4 and a compression ratio of ?248. PMID:25768188

  7. Generating nonlinear FM chirp radar signals by multiple integrations

    SciTech Connect

    Doerry, Armin W. (Albuquerque, NM)

    2011-02-01

    A phase component of a nonlinear frequency modulated (NLFM) chirp radar pulse can be produced by performing digital integration operations over a time interval defined by the pulse width. Each digital integration operation includes applying to a respectively corresponding input parameter value a respectively corresponding number of instances of digital integration.

  8. Mode selection in a multimode SAW oscillator using FM chirp mixing signal injection.

    PubMed

    Saw, C B; Smith, P M; Edmonson, P J; Campbell, C K

    1988-01-01

    Mode-selection control of a multimode surface-acoustic-wave (SAW) oscillator has been obtained using SAW linear FM chirp signal injection. The prototype 60-100-MHz SAW oscillator design employed a single-phase unidirectional transducer (SPUDT) low-loss comb filter in the feedback loop, with minimum insertion loss of approximately 3.7 dB. Mode selection was achieved using an injection signal derived from the mixed output of two 27.5-52.5-MHz up- and down-chirp SAW filters. Mode switching times of less, similar2 mus were obtained. The device could be useful as a local oscillator on frequency-agile radars, where hopping is required over a moderate number of frequencies. PMID:18290165

  9. Impact of radar systematic error on the orthogonal frequency division multiplexing chirp waveform orthogonality

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Liang, Xingdong; Chen, Longyong; Ding, Chibiao

    2015-01-01

    Orthogonal frequency division multiplexing (OFDM) chirp waveform, which is composed of two successive identical linear frequency modulated subpulses, is a newly proposed orthogonal waveform scheme for multiinput multioutput synthetic aperture radar (SAR) systems. However, according to the waveform model, radar systematic error, which introduces phase or amplitude difference between the subpulses of the OFDM waveform, significantly degrades the orthogonality. The impact of radar systematic error on the waveform orthogonality is mainly caused by the systematic nonlinearity rather than the thermal noise or the frequency-dependent systematic error. Due to the influence of the causal filters, the first subpulse leaks into the second one. The leaked signal interacts with the second subpulse in the nonlinear components of the transmitter. This interaction renders a dramatic phase distortion in the beginning of the second subpulse. The resultant distortion, which leads to a phase difference between the subpulses, seriously damages the waveform's orthogonality. The impact of radar systematic error on the waveform orthogonality is addressed. Moreover, the impact of the systematic nonlinearity on the waveform is avoided by adding a standby between the subpulses. Theoretical analysis is validated by practical experiments based on a C-band SAR system.

  10. Complex, aperiodic random signal modulation on pulse-LFM chirp radar waveform

    NASA Astrophysics Data System (ADS)

    Govoni, Mark A.; Li, Hongbin

    2010-04-01

    In an effort to enhance the security of radar, the plausibility of using a complex, aperiodic random signal to modulate a pulse linear frequency modulation (LFM) or "chirp" radar waveform across both its fast-time and slow-time samples is investigated. A non-conventional threat is considered when illustrating the effectiveness of the proposed waveform as an electronic counter-countermeasure (ECCM). Results are derived using stretch processing and are assessed using the receiver cross-correlation function with a consideration for the unmodulated case as a basis for comparison. A tailored radar ambiguity function is also included in the analysis, and is used to demonstrate how the proposed waveform possesses an ideal characteristic suitable for combating today's electronic warfare (EW) threats while preserving its inherent functionality to detect targets.

  11. Ultrafast chirped optical waveform recorder using referenced heterodyning and a time microscope

    DOEpatents

    Bennett, Corey Vincent (Livermore, CA)

    2011-11-22

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  12. Ultrafast chirped optical waveform recording using referenced heterodyning and a time microscope

    DOEpatents

    Bennett, Corey Vincent

    2010-06-15

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  13. Variable-chirped microwave waveform generator based on reconfigurable microwave photonic filter

    NASA Astrophysics Data System (ADS)

    Chen, Dalei; Wang, Rong; Pu, Tao; Fang, Tao; Xiang, Peng; Zheng, Jiling; Wei, Zhihu; Xiong, Jintian

    2014-09-01

    An optical approach to generating chirped microwave signal using a photonic microwave delay-line filter (PMDLF) with a quadratic phase response is proposed and demonstrated. In this scheme, a narrow band Gaussian pulse is used as the original signal. In order to eliminate the need for a wideband original microwave chirped-free signal, a mixer and a radio frequency signal are used to up-convert the spectrum of the original signal and the dispersion curve is tuned to minimize the attenuation caused by the fiber dispersion. Then the required frequency response can be reconstructed by a nonuniformly spaced PMDLF. Since the majority of the power of the original signal can bypass the filter, the power of the generated chirped microwave signal will be increased. A reconstruction example of a desired frequency response with a central frequency of 10 GHz is provided, and the generation of the corresponding chirped microwave signal is demonstrated by numerical simulations.

  14. Synthetic aperture acoustic imaging of canonical targets with a 2-15 kHz linear FM chirp

    NASA Astrophysics Data System (ADS)

    Vignola, Joseph F.; Judge, John A.; Good, Chelsea E.; Bishop, Steven S.; Gugino, Peter M.; Soumekh, Mehrdad

    2011-06-01

    Synthetic aperture image reconstruction applied to outdoor acoustic recordings is presented. Acoustic imaging is an alternate method having several military relevant advantages such as being immune to RF jamming, superior spatial resolution, capable of standoff side and forward-looking scanning, and relatively low cost, weight and size when compared to 0.5 - 3 GHz ground penetrating radar technologies. Synthetic aperture acoustic imaging is similar to synthetic aperture radar, but more akin to synthetic aperture sonar technologies owing to the nature of longitudinal or compressive wave propagation in the surrounding acoustic medium. The system's transceiver is a quasi mono-static microphone and audio speaker pair mounted on a rail 5meters in length. Received data sampling rate is 80 kHz with a 2- 15 kHz Linear Frequency Modulated (LFM) chirp, with a pulse repetition frequency (PRF) of 10 Hz and an inter-pulse period (IPP) of 50 milliseconds. Targets are positioned within the acoustic scene at slant range of two to ten meters on grass, dirt or gravel surfaces, and with and without intervening metallic chain link fencing. Acoustic image reconstruction results in means for literal interpretation and quantifiable analyses. A rudimentary technique characterizes acoustic scatter at the ground surfaces. Targets within the acoustic scene are first digitally spotlighted and further processed, providing frequency and aspect angle dependent signature information.

  15. CHIRP Doppler radar

    NASA Astrophysics Data System (ADS)

    Bernfeld, M.

    1984-04-01

    The present investigation is concerned with the concept of a combination of the clinical procedure of reconstruction tomography with the radar processing for linear FM pulse compression. An approach based on such a combination is to be employed to map radar backscatter energy. Radar systems employing pulse compression of linear frequency modulated (CHIRP) pulses are considered along with the inversion formula employed by reconstruction tomography. The conventional system enabling radar backscatter mapping is based on pulse-Doppler radar which basically incorporates range-gated spectrum analysis. CHIRP Doppler radar represents a potential alternative. Advantages are related to an absence of requirements to maintain coherence from pulse to pulse, and the suppression of interference due to second-time-around signals. Raabe (1976) has discussed an application involving the imaging of the wakes of reentering space vehicles.

  16. Coherent lidar imaging of dust clouds: waveform comparison with the poly-phase (P4) modulation waveform

    NASA Astrophysics Data System (ADS)

    Youmans, Douglas G.

    2008-04-01

    A dust or aerosol cloud represents a convenient target to examine the capabilities of range-resolved Doppler and intensity (RRDI) or inverse synthetic aperture ladar (ISAR) imaging coherent laser radar, known as coherent "lidar" for optically thin targets. The poly-phase P4 ladar waveform and its RRDI images are described and compared with previous pulse-burst, linear-FM chirp pulse-compression, pseudo-random phase modulation waveforms, and several other waveforms which have not been utilized to date. A "dust cloud" has very many independently moving point scatterers with velocities that are approximately Gaussian randomly distributed in x,y,z with standard deviations of about 10% of the mean wind + aerosol velocity. This is contrary to a hard-target where the point scatterers are rigidly attached and moving together. The dust cloud produced speckle effects for the various ladar waveforms are compared. In addition, a reference set of four corner-cube retro-reflectors within the dust cloud further illustrates the differences in the various waveform capabilities and resolution.

  17. The Development and Implementation of Chirped-Pulse Frequency Combs at Millimeter Wavelengths

    NASA Astrophysics Data System (ADS)

    Steber, Amanda L.; Harris, Brent J.; Neill, Justin L.; Lehmann, Kevin K.; Pate, Brooks H.

    2012-06-01

    Technological advances in such areas as active multiplier chains and high-speed digital electronics are enabling the development of sensitive high-throughput spectroscopic instruments in the millimeter and submillimeter ranges. Recently there has been an effort to develop multiplexed direct absorption spectroscopy techniques that use frequency comb sources derived from phase-locked pulse trains (often created using ultrafast lasers). We have used a high-speed arbitrary waveform generator (AWG with 12 GHz sample rate) to create frequency combs at mm-wave wavelengths using a chirped pulse as the repeating waveform. This waveform has important advantages including 100% duty cycle for the light output and compatibility with the use of frequency multiplier chains that extend the bandwidth of the comb proportional to the frequency multiplication factor. A new spectrometer operating in the 260-290 GHz range using active multiplier chains has been constructed to test the capabilities of chirped-pulse frequency comb spectroscopy for molecular rotational spectroscopy. The spectral properties of the mm-wave combs generated following x24 frequency multiplication, methods for compressed bandwidth detection using a dual-comb approach, and frequency comb analogs of FM spectroscopy will be presented.

  18. UTILIZING A CHIRP SONAR TO ACCURATELY CHARACTERIZE NEWLY DEPOSITED MATERIAL AT THE CALCASIEU OCEAN DREDGED MATERIAL DISPOSAL SITE, LOUISIANA

    EPA Science Inventory

    The distribution of dredged sediments is measured at the Calcasieu Ocean Dredged Material Disposal Site (ODMDS) using a chirp sonar immediately after disposal and two months later. ubbottom reflection data, generated by a chirp sonar transmitting a 4 to 20 kHz FM sweep, is proces...

  19. Frequency-hopped-waveform synthesis with a surface-acoustic-wave tapped delay line

    Microsoft Academic Search

    G. Manes; P. Grant

    1976-01-01

    A coherent frequency-hopped-waveform synthesizer, based on the detection of contradirected chirp signals within a surface-acoustic-wave tapped delay line, is reported. Attractive features are programmable bandwidth and hop duration through control of external chirps, plus the capability to synthesize many simultaneous coherent outputs.

  20. Phase-locking and coherent power combining of broadband linearly chirped optical waves.

    PubMed

    Satyan, Naresh; Vasilyev, Arseny; Rakuljic, George; White, Jeffrey O; Yariv, Amnon

    2012-11-01

    We propose, analyze and demonstrate the optoelectronic phase-locking of optical waves whose frequencies are chirped continuously and rapidly with time. The optical waves are derived from a common optoelectronic swept-frequency laser based on a semiconductor laser in a negative feedback loop, with a precisely linear frequency chirp of 400 GHz in 2 ms. In contrast to monochromatic waves, a differential delay between two linearly chirped optical waves results in a mutual frequency difference, and an acoustooptic frequency shifter is therefore used to phase-lock the two waves. We demonstrate and characterize homodyne and heterodyne optical phase-locked loops with rapidly chirped waves, and show the ability to precisely control the phase of the chirped optical waveform using a digital electronic oscillator. A loop bandwidth of ~ 60 kHz, and a residual phase error variance of < 0.01 rad(2) between the chirped waves is obtained. Further, we demonstrate the simultaneous phase-locking of two optical paths to a common master waveform, and the ability to electronically control the resultant two-element optical phased array. The results of this work enable coherent power combining of high-power fiber amplifiers-where a rapidly chirping seed laser reduces stimulated Brillouin scattering-and electronic beam steering of chirped optical waves. PMID:23187338

  1. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2004-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital ONEs or ZEROs. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental natural laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  2. Carrier Modulation Via Waveform Probability Density Function

    NASA Technical Reports Server (NTRS)

    Williams, Glenn L.

    2006-01-01

    Beyond the classic modes of carrier modulation by varying amplitude (AM), phase (PM), or frequency (FM), we extend the modulation domain of an analog carrier signal to include a class of general modulations which are distinguished by their probability density function histogram. Separate waveform states are easily created by varying the pdf of the transmitted waveform. Individual waveform states are assignable as proxies for digital one's or zero's. At the receiver, these states are easily detected by accumulating sampled waveform statistics and performing periodic pattern matching, correlation, or statistical filtering. No fundamental physical laws are broken in the detection process. We show how a typical modulation scheme would work in the digital domain and suggest how to build an analog version. We propose that clever variations of the modulating waveform (and thus the histogram) can provide simple steganographic encoding.

  3. Waveform analysis

    NASA Astrophysics Data System (ADS)

    2010-04-01

    Accurate characterization of ultrafast optical pulses is important for applications such as spectroscopy and communications research. S. J. Ben Yoo from the University of California at Davis explains his team's scheme for real-time measurement of the amplitude and phase of arbitrary and non-repetitive waveforms.

  4. Chirp signal matching and signal power optimization in pulse-echo mode ultrasonic nondestructive testing

    Microsoft Academic Search

    Martin Pollakowski; Helmut Ermert

    1994-01-01

    Chirp pulse compression is a signal correlation technique that uses frequency modulated pulses as transmitted signals. Usually, signals with linear frequency modulation are applied. They can be generated rather easily, but their spectra are not totally matched to the transfer function of ultrasonic systems. In pulse-echo mode operation, with signal duration and consequently the time-bandwidth product being critical parameters, waveforms

  5. Frequency chirping in external modulators

    Microsoft Academic Search

    Fumio Koyama; KENICHI IGA

    1988-01-01

    A general formula is given that expresses frequency chirping in some types of external intensity modulators, such as the loss modulator, directional-coupler-type modulator, Mach-Zehnder interferometry-type modulator, and total-internal-reflection-type modulator. The chirping phenomenon treated is caused by the phase modulation due to an accompanied refractive index change. It is uniquely expressed in terms of an ?-parameter that contributes to frequency chirping

  6. Super-resolution processing for multi-functional LPI waveforms

    NASA Astrophysics Data System (ADS)

    Li, Zhengzheng; Zhang, Yan; Wang, Shang; Cai, Jingxiao

    2014-05-01

    Super-resolution (SR) is a radar processing technique closely related to the pulse compression (or correlation receiver). There are many super-resolution algorithms developed for the improved range resolution and reduced sidelobe contaminations. Traditionally, the waveforms used for the SR have been either phase-coding (such as LKP3 code, Barker code) or the frequency modulation (chirp, or nonlinear frequency modulation). There are, however, an important class of waveforms which are either random in nature (such as random noise waveform), or randomly modulated for multiple function operations (such as the ADS-B radar signals in [1]). These waveforms have the advantages of low-probability-of-intercept (LPI). If the existing SR techniques can be applied to these waveforms, there will be much more flexibility for using these waveforms in actual sensing missions. Also, SR usually has great advantage that the final output (as estimation of ground truth) is largely independent of the waveform. Such benefits are attractive to many important primary radar applications. In this paper the general introduction of the SR algorithms are provided first, and some implementation considerations are discussed. The selected algorithms are applied to the typical LPI waveforms, and the results are discussed. It is observed that SR algorithms can be reliably used for LPI waveforms, on the other hand, practical considerations should be kept in mind in order to obtain the optimal estimation results.

  7. Transionospheric chirp event classifier

    SciTech Connect

    Argo, P.E.; Fitzgerald, T.J.; Freeman, M.J.

    1995-09-01

    In this paper we will discuss a project designed to provide computer recognition of the transionospheric chirps/pulses measured by the Blackbeard (BB) satellite, and expected to be measured by the upcoming FORTE satellite. The Blackbeard data has been perused by human means -- this has been satisfactory for the relatively small amount of data taken by Blackbeard. But with the advent of the FORTE system, which by some accounts might ``see`` thousands of events per day, it is important to provide a software/hardware method of accurately analyzing the data. In fact, we are providing an onboard DSP system for FORTE, which will test the usefulness of our Event Classifier techniques in situ. At present we are constrained to work with data from the Blackbeard satellite, and will discuss the progress made to date.

  8. FM 6-22 (FM 22-100) Army Leadership

    E-print Network

    US Army Corps of Engineers

    FM 6-22 (FM 22-100) Army Leadership Competent, Confident, and Agile OCTOBER 2006 DISTRIBUTION and complex security environment we face. FM 6-22 is the Army's keystone field manual on leadership. It establishes leadership doctrine and fundamental principles for all officers, noncommissioned officers

  9. JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 32, NO. 20, OCTOBER 15, 2014 3573 Generation of Linearly Chirped Microwave

    E-print Network

    Yao, Jianping

    ), in the order of 102 or 103 , is required. In the electrical domain, such an LCMW can be generated usingJOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 32, NO. 20, OCTOBER 15, 2014 3573 Generation of Linearly Chirped Microwave Waveform With an Increased Time-Bandwidth Product Based on a Tunable Optoelectronic

  10. Photonic chirped radio-frequency generator with ultra-fast sweeping rate and ultra-wide sweeping range.

    PubMed

    Wun, Jhih-Min; Wei, Chia-Chien; Chen, Jyehong; Goh, Chee Seong; Set, S Y; Shi, Jin-Wei

    2013-05-01

    A high-performance photonic sweeping-frequency (chirped) radio-frequency (RF) generator has been demonstrated. By use of a novel wavelength sweeping distributed-feedback (DFB) laser, which is operated based on the linewidth enhancement effect, a fixed wavelength narrow-linewidth DFB laser, and a wideband (dc to 50 GHz) photodiode module for the hetero-dyne beating RF signal generation, a very clear chirped RF waveform can be captured by a fast real-time scope. A very-high frequency sweeping rate (10.3 GHz/?s) with an ultra-wide RF frequency sweeping range (~40 GHz) have been demonstrated. The high-repeatability (~97%) in sweeping frequency has been verified by analyzing tens of repetitive chirped waveforms. PMID:23670004

  11. First results of a deep tow CHIRP sonar seafloor imaging system

    USGS Publications Warehouse

    Parent, M.; Fang, Changle; O'Brien, Thomas F.; Danforth, William W.

    1993-01-01

    The latest and most innovative technology has been applied towards the development of a full-ocean depth multi-sensor sonar system using linear swept-FM (Chirp) technology. The seafloor imaging system (SIS- 7000) described herein uses Chirp sidescan sonar to provide high resolution imagery at long range, and Chirp subbottom sonar to provide high resolution profiles in both the near bottom and deeper subbottom. The tow vehicle contains a suite of full-ocean depth instrumentation for measuring various oceanographic parameters and for monitoring vehicle status. Top side systems include a sonar display and data logging system as well as real-time sensor status display and tow vehicle control system. This paper will present an overview of this system, describe its technology and capabilities, and present some initial results. 

  12. Digital FM double errors

    Microsoft Academic Search

    R. F. Pawula

    2001-01-01

    This paper evaluates the double-error probability (average probability of two consecutive bit errors) in digital FM for a noncoherent limiter\\/discriminator receiver with either integrate and dump or sample and hold (S&H) bit detection. A remarkably simple relationship is found relating the S&H double-error probability to the optimum coherent CPFSK bit error probability of Osborne and Luntz (1974)

  13. A 32x32 pixel focal plane array ladar system using chirped amplitude modulation

    Microsoft Academic Search

    Barry L. Stann; Keith Aliberti; Daniel Carothers; John Dammann; Gerard Dang; Mark M. Giza; William B. Lawler; Brian C. Redman; Deborah R. Simon

    2004-01-01

    The Army Research Laboratory is researching system architectures and components required to build a 32x32 pixel scannerless ladar breadboard. The 32x32 pixel architecture achieves ranging based on a frequency modulation\\/continuous wave (FM\\/cw) technique implemented by directly amplitude modulating a near-IR diode laser transmitter with a radio frequency (RF) subcarrier that is linearly frequency modulated (i.e. chirped amplitude modulation). The backscattered

  14. Adaptive MIMO radar waveforms

    Microsoft Academic Search

    Daniel J. Rabideau; Lexington MA

    2008-01-01

    Multiple-Input, Multiple-Output (MIMO) radars enhance performance by transmitting and receiving coded waveforms from multiple locations. To date, the theoretical literature on MIMO radar has focused largely on the use of ldquoorthogonal waveforms.rdquo Practical approaches to approximate orthogonality (e.g., via waveforms characterized by low cross-correlation and low autocorrelation sidelobe levels) have also started to emerge. We show, however, that such waveforms

  15. Waveform-Generating Program

    NASA Technical Reports Server (NTRS)

    Hopson, Charles B.

    1991-01-01

    GENERATE (Digital Generation of Complex Waveforms) computer program is flexible and reliable software tool for advanced generation of waveforms. User employs standard arithmetic operator (+, -, x, /, and parentheses) to simulate any combination of eight commonly used basic waveforms at desired amplitude and frequency. Creates data file based on user's selections from menu. Provides necessary equations describing eight basic waveforms and enables user to combine them arithmetically. Basic waveforms offered as building blocks; sine, ramp, exponential, logarithmic, step, clipped sine, square, and sawtooth. Also contains routine for plotting output waveform data on terminal with Tektronics (or equivalent) emulator, providing visual confirmation of desirability of waveform. Developed by use of VMS FORTRAN on DEC VAX 3600 computer.

  16. Full-field reconstruction of ultrashort waveforms by time to space conversion interferogram analysis.

    PubMed

    Shayovitz, Dror; Herrmann, Harald; Sohler, Wolfgang; Ricken, Raimund; Silberhorn, Christine; Marom, Dan M

    2014-08-25

    Accurate amplitude and phase measurements of ultrashort optical waveforms are essential for their use in a wide range of scientific disciplines. Here we report the first demonstration of full-field optical reconstruction of ultrashort waveforms using a time-to-space converter, followed by a spatial recording of an interferogram. The algorithm-free technique is demonstrated by measuring ultrashort pulses that are widely frequency chirped from negative to positive, as well as phase modulated pulse packets. Amplitude and phase measurements were recorded for pulses ranging from 0.5 ps to 10 ps duration, with measured dimensionless chirp parameter values from -30 to 30. The inherently single-shot nature of time-to-space conversion enables full-field measurement of complex and non-repetitive waveforms. PMID:25321230

  17. Tone signal generator for producing multioperator tone signals using an operator circuit including a waveform generator, a selector and an enveloper

    DOEpatents

    Dong, Q.; Jenkins, M.V.; Bernadas, S.R.

    1997-09-09

    A frequency modulation (FM) tone signal generator for generating a FM tone signal is disclosed. The tone signal generator includes a waveform generator having a plurality of wave tables, a selector and an enveloper. The waveform generator furnishes a waveform signal in response to a phase angle address signal. Each wave table stores a different waveform. The selector selects one of the wave tables in response to a plurality of selection signals such that the selected wave table largely provides the waveform signal upon being addressed largely by the phase angle address signal. Selection of the selected wave table varies with each selection signal. The enveloper impresses an envelope signal on the waveform signal. The envelope signal is used as a carrier or modulator for generating the FM tone signal. 17 figs.

  18. Hybrid chirped pulse amplification system

    DOEpatents

    Barty, Christopher P.; Jovanovic, Igor

    2005-03-29

    A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

  19. Waveform: Acoustics/Electroacoustics

    NSDL National Science Digital Library

    This webpage from the Handbook for Acoustic Ecology provides a description of waveform, a pattern of sound pressure variation. Information includes linked explanations of numerous related terms like sound pressure, amplitude, and the law of superposition. Also incorporated into the site are sound clips of various waveforms such as sine, sawtooth, and triangle waves.

  20. An MSK Radar Waveform

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater spectral efficiency than the MSK waveform, such as linear frequency modulation (LFM) and Costas frequency hopping, have a fixed peak sidelobe level that is therefore not configurable, and can be exceeded by high contrast targets. Furthermore, in the case of a multistatic experiment observing a target in motion, self-interference from the transmitter to the receiver is mitigated by the MSK waveform. Waveforms that have delay Doppler coupling, such as LFM, provide no such protection.

  1. Arterial waveform analysis.

    PubMed

    Esper, Stephen A; Pinsky, Michael R

    2014-12-01

    The bedside measurement of continuous arterial pressure values from waveform analysis has been routinely available via indwelling arterial catheterization for >50 years. Invasive blood pressure monitoring has been utilized in critically ill patients, in both the operating room and critical care units, to facilitate rapid diagnoses of cardiovascular insufficiency and monitor response to treatments aimed at correcting abnormalities before the consequences of either hypo- or hypertension are seen. Minimally invasive techniques to estimate cardiac output (CO) have gained increased appeal. This has led to the increased interest in arterial waveform analysis to provide this important information, as it is measured continuously in many operating rooms and intensive care units. Arterial waveform analysis also allows for the calculation of many so-called derived parameters intrinsically created by this pulse pressure profile. These include estimates of left ventricular stroke volume (SV), CO, vascular resistance, and during positive-pressure breathing, SV variation, and pulse pressure variation. This article focuses on the principles of arterial waveform analysis and their determinants, components of the arterial system, and arterial pulse contour. It will also address the advantage of measuring real-time CO by the arterial waveform and the benefits to measuring SV variation. Arterial waveform analysis has gained a large interest in the overall assessment and management of the critically ill and those at a risk of hemodynamic deterioration. PMID:25480767

  2. Low frequency AC waveform generator

    DOEpatents

    Bilharz, Oscar W. (Scotia, NY)

    1986-01-01

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stabilization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform itself. The cosine is synthesized by squaring the triangular waveform, raising the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  3. Transionospheric signal detection with chirped wavelets

    SciTech Connect

    Doser, A.B.; Dunham, M.E.

    1997-11-01

    Chirped wavelets are utilized to detect dispersed signals in the joint time scale domain. Specifically, pulses that become dispersed by transmission through the ionosphere and are received by satellites as nonlinear chirps are investigated. Since the dispersion greatly lowers the signal to noise ratios, it is difficult to isolate the signals in the time domain. Satellite data are examined with discrete wavelet expansions. Detection is accomplished via a template matching threshold scheme. Quantitative experimental results demonstrate that the chirped wavelet detection scheme is successful in detecting the transionospheric pulses at very low signal to noise ratios.

  4. Phase-shifted distributed feedback laser with linearly chirped grating fabricated by reconstruction equivalent chirp technique

    NASA Astrophysics Data System (ADS)

    Li, Lianyan; Lu, Linlin; Li, Simin; Guo, Renjia; Shi, Yuechun; Chen, Xiangfei

    2014-09-01

    The phase-shifted distributed feedback (DFB) semiconductor laser with linearly chirped grating based on reconstruction equivalent chirp (REC) technique is theoretically analyzed and experimentally demonstrated for the first time. The asymmetric property of the lasing spectrum is analyzed according to the normalized threshold gain, and the different spectra from each facet of the laser are compared. Due to the low cost and fabrication flexibility, REC technique provides a promising way for the future practical applications of DFB lasers with chirped gratings.

  5. Adaptive Chirp Beamforming for Direction-of-Arrival Estimation of Wideband Chirp Signals in Sensor Arrays

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Soo; Choi, Byung-Woong; Bae, Eun-Hyon; Lee, Kyun-Kyung

    An adaptive chirp beamforming method is proposed to solve the bias problem in the direction-of-arrival (DOA) estimation of wideband chirp signals that have identical time-frequency parameters yet emanate from different directions. The proposed method, based on the steered minimum variance (STMV) method, exploits the time-frequency structure of a chirp signal to improve the DOA estimation performance by effectively suppressing the wideband chirp interferences causing the bias. Simulations are performed to demonstrate the effectiveness of the proposed method.

  6. CHIRP

    Cancer.gov

    Skip to Main Content Headlines Pediatric Oncology Branch Home > Pediatric Psycho-Oncology Professionals > Training Headline Title Pediatric Psycho-Oncology Professionals Pediatric Psychology Postdoctoral Fellowship University of Louisville School of

  7. Optical chirped beam amplification and propagation

    DOEpatents

    Barty, Christopher P.

    2004-10-12

    A short pulse laser system uses dispersive optics in a chirped-beam amplification architecture to produce high peak power pulses and high peak intensities without the potential for intensity dependent damage to downstream optical components after amplification.

  8. FM 3-04.113 (FM 1-113) Utility and Cargo Helicopter Operations

    E-print Network

    US Army Corps of Engineers

    FM 3-04.113 (FM 1-113) Utility and Cargo Helicopter Operations December 2007 DISTRIBUTION Helicopter Operations Contents Page PREFACE ........................................................................................ 1-3 Assault Helicopter Battalion

  9. Application of the effective Fisher matrix to the frequency domain inspiral waveforms

    NASA Astrophysics Data System (ADS)

    Cho, Hee-Suk; Lee, Chang-Hwan

    2014-12-01

    The Fisher matrix (FM) has been generally used to predict the accuracy of the gravitational wave parameter estimation. Although the limitation of the FM has been well known, it is still mainly used due to its very low computational cost compared to the Monte Carlo simulations. Recently, Rodriguez et al (2013 Phys. Rev. D 88 084013) performed Markov chain Monte Carlo (MCMC) simulations using a frequency domain inspiral waveform model (TaylorF2) for nonspinning binary systems with total masses M?slant 20{{M}? }, and they found systematic differences between the predictions from FM and MCMC for M\\gt 10{{M}? }. On the other hand, an effective Fisher matrix (eFM) was recently introduced by Cho et al (2013 Phys. Rev. D 87 24004). The eFM is a semi-analytic approach to the standard FM, in which the derivative is taken of a quadratic function fitted to the local overlap surface. In this work, we apply the eFM method to the TaylorF2 waveform for nonspinning binary systems with a moderately high signal-to-noise ratio (SNR˜ 15) and find that the eFM can reproduce the MCMC error bounds in Rodriguez et al well, even for high masses. By comparing the eFM standard deviation directly with the 1-? confidence interval of the marginalized overlap that approximates the MCMC posterior distribution, we show that the eFM can be acceptable in all mass regions for the estimation of the MCMC error bounds. We also investigate the dependence on the signal strength.

  10. Low frequency ac waveform generator

    DOEpatents

    Bilharz, O.W.

    1983-11-22

    Low frequency sine, cosine, triangle and square waves are synthesized in circuitry which allows variation in the waveform amplitude and frequency while exhibiting good stability and without requiring significant stablization time. A triangle waveform is formed by a ramped integration process controlled by a saturation amplifier circuit which produces the necessary hysteresis for the triangle waveform. The output of the saturation circuit is tapped to produce the square waveform. The sine waveform is synthesized by taking the absolute value of the triangular waveform, raising this absolute value to a predetermined power, multiplying the raised absolute value of the triangle wave with the triangle wave itself and properly scaling the resultant waveform and subtracting it from the triangular waveform to a predetermined power and adding the squared waveform raised to the predetermined power with a DC reference and subtracting the squared waveform therefrom, with all waveforms properly scaled. The resultant waveform is then multiplied with a square wave in order to correct the polarity and produce the resultant cosine waveform.

  11. Interplay of the Chirps and Chirped Pulse Compression in a High-gain Seeded Free-electron Laser

    SciTech Connect

    Wu, Juhao; /SLAC; Murphy, J.B.; /LBNL, ALS; Emma, P.J.; /SLAC; Wang, X.J.; Watanabe, T.; /LBNL, ALS; Zhong, Xinming; /Beijing Normal U.

    2007-01-03

    In a seeded high-gain Free-electron Laser (FEL), where a coherent laser pulse interacts with an ultra-relativistic electron beam, the seed laser pulse can be frequency chirped, and the electron beam can be energy chirped. Besides these two chirps, the FEL interaction introduces an intrinsic frequency chirp in the FEL even if the above mentioned two chirps are absent. In this paper we examine the interplay of these three chirps. The problem is formulated as an initial value problem, and solved via a Green function approach. Besides the chirp evolution, we also give analytical expressions for the pulse duration and bandwidth of the FEL, which remains fully longitudinally coherent in the high gain exponential growth regime. Because the chirps are normally introduced for a final compression of the FEL pulse, some conceptual issues are discussed. We show that in order to get a short pulse duration, an energy chirp in the electron beam is necessary.

  12. Adaptive chirp-Fourier transform for chirp estimation with applications in ISAR imaging of maneuvering targets

    NASA Astrophysics Data System (ADS)

    Xia, Xiang-Gen; Wang, Genyuan; Chen, Victor C.

    2001-03-01

    This paper first reviews some basic properties of the discrete chirp-Fourier transform and then present an adaptive chirp- Fourier transform, a generalization of the amplitude and phase estimation of sinusoids (APES) algorithm proposed by Li and Stoica for sinusoidal signals. We finally applied it to the ISAR imaging of maneuvering targets.

  13. Optical waveform generation using a directly modulated laser

    NASA Astrophysics Data System (ADS)

    Cartledge, John C.; Karar, Abdullah S.; Roberts, Kim

    2013-10-01

    The capability of a directly modulated laser (DML) can be dramatically enhanced through precise control of the drive current waveform based on digital signal processing (DSP) and a digital-to-analog convertor (DAC). In this paper, a novel method to pre-compensate fiber dispersion for metro and regional networks is described for a bit rate of 10.709 Gb/s using a DML. A look-up table (LUT) for the drive current is optimized for dispersion mitigation. The entries of the LUT are determined based on the effects of the DML adiabatic and transient chirp on pulse propagation, the nonlinear mapping between the input current and the output optical power, and the bandwidth of the DML package. A DAC operating at 2 samples per bit (21.418 GSa/s with 6 bit resolution) converts the digital samples at the output of the LUT to an analog current waveform driving the DML. Experimental results for a bit rate of 10.709 Gb/s and on-off keying demonstrate a transmission reach of 252 km using a DML intended for 2.5 Gb/s operation and 608 km using a chirp managed laser intended for 10 Gb/s operation. Using this approach (DSP + DAC), the generation of 10.709 Gb/s differential phase shift keying (DPSK) and 56 Gb/s 16-ary quadrature amplitude modulation, sub-carrier multiplexed (QAM SCM) optical signals using the direct modulation of a passive feedback laser is also presented. 6-bit DACs operating at sampling rates of 21.418 GSa/s and 28 GSa/s, respectively, was used to generate the requisite analog current waveform.

  14. High precision triangular waveform generator

    Microsoft Academic Search

    1983-01-01

    An ultra-linear ramp generator having separately programmable ascending and descending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by

  15. Optical FM Demodulation by Fibre Bragg Grating

    Microsoft Academic Search

    Jaroslaw Z. Sotor; Arkadiusz J. Antonczak; Krzysztof M. Abramski

    2007-01-01

    In this paper the application of fibre Bragg grating (FBG) as a FM demodulator is presented. Two types of FBG were investigated: with and without athermal package. Main factors limited application of FBG to FM demodulation such as thermal stability, slope of the FBG and dark current of photodetector were discussed. Maximum and minimum FM deviation possible to demodulate for

  16. a Chirped-Pulse Fourier Transform Spectrometer Operating from 110 TO 170 GHZ

    NASA Astrophysics Data System (ADS)

    Bernier, Lauren E.; Shipman, Steven

    2014-06-01

    A chirped-pulse Fourier transform spectrometer operating from 110 - 170 GHz was constructed. The design of this spectrometer is directly adapted from that of the 260 - 295 GHz chirped-pulse spectrometer built by Steber and co-workers at the University of Virginia. In this instrument, an arbitrary waveform generator (AWG) produces a chirped pulse which is frequency shifted to a range between 9.2 and 14.1 GHz and then multiplied by a factor of 12 via an active multiplier chain to a range between 110 and 170 GHz. As in the Pate lab design, the AWG also serves as a local oscillator (LO) source; this LO is multiplied and used to downconvert the molecular emission, allowing it to be collected by a 40 GS/s digitizer. Benchmark measurements were taken for methanol at room temperature, and details of the instrument's performance will be discussed. A.L. Steber, B.J. Harris, J.L. Neill, and B.H. Pate, J. Mol. Spectrosc., 280, 3 (2012)

  17. FM use of BM PPT

    E-print Network

    Brady, L.

    2012-01-01

    Accuracy Interoperability/ IFC Support 2 3 4 5 6 7 8 9 10 1 0 Maturity Level ? Link to fire strategy / evacuation plan ? Link to security strategy ? Thermal modelling building changes ? Link to digital Signage. ? Using BIM (hand held... FM Team Embedded within Design development MCC : Cabinet Office BIM Workshops MCC : Cabinet Office Soft Landings Workshop Transferring BIM data for operational use. C-Pad C O B i e - U K - 2 0 1 2 Manual Data EDMS Content...

  18. Quantum optical waveform conversion

    E-print Network

    D Kielpinski; JF Corney; HM Wiseman

    2010-10-11

    Currently proposed architectures for long-distance quantum communication rely on networks of quantum processors connected by optical communications channels [1,2]. The key resource for such networks is the entanglement of matter-based quantum systems with quantum optical fields for information transmission. The optical interaction bandwidth of these material systems is a tiny fraction of that available for optical communication, and the temporal shape of the quantum optical output pulse is often poorly suited for long-distance transmission. Here we demonstrate that nonlinear mixing of a quantum light pulse with a spectrally tailored classical field can compress the quantum pulse by more than a factor of 100 and flexibly reshape its temporal waveform, while preserving all quantum properties, including entanglement. Waveform conversion can be used with heralded arrays of quantum light emitters to enable quantum communication at the full data rate of optical telecommunications.

  19. Multiscale full waveform inversion

    NASA Astrophysics Data System (ADS)

    Fichtner, Andreas; Trampert, Jeannot; Cupillard, Paul; Saygin, Erdinc; Taymaz, Tuncay; Capdeville, Yann; Villaseñor, Antonio

    2013-07-01

    We develop and apply a full waveform inversion method that incorporates seismic data on a wide range of spatio-temporal scales, thereby constraining the details of both crustal and upper-mantle structure. This is intended to further our understanding of crust-mantle interactions that shape the nature of plate tectonics, and to be a step towards improved tomographic models of strongly scale-dependent earth properties, such as attenuation and anisotropy. The inversion for detailed regional earth structure consistently embedded within a large-scale model requires locally refined numerical meshes that allow us to (1) model regional wave propagation at high frequencies, and (2) capture the inferred fine-scale heterogeneities. The smallest local grid spacing sets the upper bound of the largest possible time step used to iteratively advance the seismic wave field. This limitation leads to extreme computational costs in the presence of fine-scale structure, and it inhibits the construction of full waveform tomographic models that describe earth structure on multiple scales. To reduce computational requirements to a feasible level, we design a multigrid approach based on the decomposition of a multiscale earth model with widely varying grid spacings into a family of single-scale models where the grid spacing is approximately uniform. Each of the single-scale models contains a tractable number of grid points, which ensures computational efficiency. The multi-to-single-scale decomposition is the foundation of iterative, gradient-based optimization schemes that simultaneously and consistently invert data on all scales for one multi-scale model. We demonstrate the applicability of our method in a full waveform inversion for Eurasia, with a special focus on Anatolia where coverage is particularly dense. Continental-scale structure is constrained by complete seismic waveforms in the 30-200 s period range. In addition to the well-known structural elements of the Eurasian mantle, our model reveals a variety of subtle features, such as the Armorican Massif, the Rhine Graben and the Massif Central. Anatolia is covered by waveforms with 8-200 s period, meaning that the details of both crustal and mantle structure are resolved consistently. The final model contains numerous previously undiscovered structures, including the extension-related updoming of lower-crustal material beneath the Menderes Massif in western Anatolia. Furthermore, the final model for the Anatolian region confirms estimates of crustal depth from receiver function analysis, and it accurately explains cross-correlations of ambient seismic noise at 10 s period that have not been used in the tomographic inversion. This provides strong independent evidence that detailed 3-D structure is well resolved.

  20. Chirp generated acoustic wavefield images

    NASA Astrophysics Data System (ADS)

    Michaels, Thomas E.; Michaels, Jennifer E.; Lee, Sang Jun; Chen, Xin

    2011-04-01

    Guided waves are being considered for structural health monitoring (SHM) applications, and they can also be used to reduce subsequent inspection times once defects are detected. One proposed SHM method is to use an array of permanently attached piezoelectric transducers to generate and receive guided waves between the various transducer pairs. The interrogation can be done on a continuous or periodic basis to assess the health of the structure. Once defects are suspected in the structure, the traditional approach is to disassemble components for conventional nondestructive evaluation (NDE); however, this is an expensive and time consuming process. A less expensive alternative to conventional NDE is to record acoustic wavefield images of guided waves generated from the attached transducers. These images clearly show details of guided waves as they propagate outward from the source, reflect from structural discontinuities and specimen boundaries, and scatter from any damage sites within the structure. However, the recorded waves are typically narrowband to enable effective visualization of echoes that are relatively compact in time. In this paper, we consider wavefield images that are recorded from a chirp excitation, which offers the advantage of high quality broadband data from a single excitation. However, responses are not directly useful because the received echoes are too extended in time. Signals are post-processed to obtain multiple narrowband and broadband responses containing echoes that are more compact in time to enable visualization of guided waves interacting with structural features. This technique is demonstrated on an aluminum plate that contains attached stiffeners and glued-on piezoelectric disc transducers. Wavefield data are recorded using an air-coupled transducer scanned over the plate surface while one of the attached transducers acts as a guided wave source. Waves interacting with the stiffener and the inactive discs are analyzed via broadband and narrowband processing at multiple frequencies.

  1. Improved transmission performance resulting from the reduced chirp of a semiconductor laser coupled to an external high-Q resonator

    SciTech Connect

    Cartledge, J.C. (Bellcore, Red Bank, NJ (US))

    1990-05-01

    The coupling of a Fabry--Perot laser to an external high-{ital Q} resonator, whose resonance frequencies are not altered by changes in the carrier density, yields a dynamic single-longitudinal-mode laser with a significantly reduced transient frequency chirp. The improvement in the receiver sensitivity due to the reduced chirp is examined for NRZ and RZ intensity modulation, direct detection systems operating in the 1.55-{mu}m wavelength region with conventional single-mode optical fiber. The methodology involves a solving modified rate equations numerically for the optical power and phase of the external resonator laser in response to an injected current waveform, modeling the signal transmission properties of single-mode optical fibers by convolution and modulus squared operations, and using a truncated pulse train approximation to evaluate the probability of error in the presence of intersymbol interference, shot noise, APD multiplication noise, and preamplifier circuit noise.

  2. Enhancement of sound in chirped sonic crystals

    NASA Astrophysics Data System (ADS)

    Romero-García, V.; Picó, R.; Cebrecos, A.; Sánchez-Morcillo, V. J.; Staliunas, K.

    2013-03-01

    We propose and experimentally demonstrate a mechanism of sound wave concentration based on soft reflections in chirped sonic crystals. The reported controlled field enhancement occurs at around particular (bright) planes in the crystal and is related to a progressive slowing down of the sound wave as it propagates along the material. At these bright planes, a substantial concentration of the energy (with a local increase up to 20 times) was obtained for a linear chirp and for frequencies around the first band gap. A simple couple mode theory is proposed that interprets and estimates the observed effects. Wave concentration energy can be applied to increase the efficiency of detectors and absorbers.

  3. Dispersive propagation of a chirped laser pulse

    NASA Astrophysics Data System (ADS)

    Hallidy, W. H.

    Dispersive effects on the phase of a chirped infrared CO2 laser pulse propagating vertically through the atmosphere are determined. The dispersion is modeled using a Voigt type of integral. The line strength and line broadening are calculated as functions of height using the McClatchey tables for their sea level values. Changes in phase over the chirp width are then found by numerical integration with respect to height for heights to 50 km for the CO2 P20 and P22 lines in the 1.4-micron band.

  4. High precision triangular waveform generator

    DOEpatents

    Mueller, Theodore R. (Oak Ridge, TN)

    1983-01-01

    An ultra-linear ramp generator having separately programmable ascending and descending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  5. On the relationship between pump chirp and single-photon chirp in spontaneous parametric downconversion

    E-print Network

    X. Sanchez-Lozano; A. B. U'Ren; J. L. Lucio

    2012-06-04

    We study the chronocyclic character, i.e. the joint temporal and spectral properties, of the single-photon constituents of photon pairs generated by spontaneous parametric down conversion. In particular we study how single photon properties, including purity and single-photon chirp, depend on photon pair properties, including the type of signal-idler spectral and correlations and the level of pump chirp.

  6. Time reversed photonic beamforming of arbitrary waveform ladar arrays

    NASA Astrophysics Data System (ADS)

    Cox, Joseph L.; Zmuda, Henry; Bussjaeger, Rebecca J.; Erdmann, Reinhard K.; Fanto, Michael L.; Hayduk, Michael J.; Malowicki, John E.

    2007-04-01

    Herein is described a novel approach of performing adaptive photonic beam forming of an array of optical fibers with the expressed purpose of performing laser ranging. The beam forming technique leverages the concepts of time reversal, previously implemented in the sonar community, and wherein photonic implementation has recently been described for use by beamforming of ultra-wideband radar arrays. Photonic beam forming is also capable of combining the optical output of several fiber lasers into a coherent source, exactly phase matched on a pre-determined target. By implementing electro-optically modulated pulses from frequency chirped femtosecond-scale laser pulses, ladar waveforms can be generated with arbitrary spectral and temporal characteristics within the limitations of the wide-band system. Also described is a means of generating angle/angle/range measurements of illuminated targets.

  7. Self-imaging chirped holographic optical waveguides.

    PubMed

    Grebel, H; Graziani, J L; Vijayalakshmi, S; Shacklette, L W; Stengel, K M; Eldada, L; Norwood, R; Yardley, J T

    1997-12-20

    To manipulate light propagation in optical waveguides, we have studied holographic, chirped structures within the waveguide's core. The holographic structures were embedded along the wave propagation direction and extended throughout the entire guide. Various self-imaging guides have been analyzed and realized to demonstrate the effect of different structures. PMID:18264499

  8. Self-Imaging Chirped Holographic Optical Waveguides

    Microsoft Academic Search

    Haim Grebel; Jean-Luc Graziani; Sankaran Vijayalakshmi; Lawrence W. Shacklette; Kelly M. T. Stengel; Louay Eldada; Robert Norwood; James T. Yardley

    1997-01-01

    To manipulate light propagation in optical waveguides, we have studied holographic, chirped structures within the waveguide s core. The holographic structures were embedded along the wave propagation direction and extended throughout the entire guide. Various self-imaging guides have been analyzed and realized to demonstrate the effect of different structures.

  9. Unambiguous evaluation of a chirp measurement standard

    NASA Astrophysics Data System (ADS)

    Seewig, Jörg; Eifler, Matthias; Wiora, Georg

    2014-10-01

    This article describes an automated evaluation method for the chirp standard. Chirp calibration standards provide a way to describe the transfer behavior of different spatial frequencies as they contain sinusoidal functions of varying wavelengths (Krüger-Sehm et al 2007 chirp calibration standards for surface measuring instruments Tech. Mess. tm 74 572–76 Pehnelt et al 2011 Comparative analysis of optical surface measuring systems with a chip calibration standard Tech. Mess. tm 78 457–62). By introducing a new, automated evaluation method, an improvement for the application of the chirp standard can be achieved. The data-preprocessing for topography and profile measurement data and the fit of the geometric elements are described. Automated evaluation can reduce the labor required to evaluate measured data and make it easier to compare different evaluations in the course of standardization. The algorithm can be used to characterize the so-called ‘small scale fidelity’ of an optical instrument. The term ‘small scale fidelity’ is currently discussed in the optical group of working group no. 16 of the ISO technical committee 213.

  10. FM 2-22.3 (FM 34-52) HUMAN INTELLIGENCE

    E-print Network

    US Army Corps of Engineers

    FM 2-22.3 (FM 34-52) HUMAN INTELLIGENCE COLLECTOR OPERATIONS HEADQUARTERS, DEPARTMENT OF THE ARMY Washington, DC, 6 September 2006 Human Intelligence Collector Operations Contents Page PREFACE...................................................................................................1-1 Intelligence Battlefield Operating System

  11. STRS Compliant FPGA Waveform Development

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer; Downey, Joseph; Mortensen, Dale

    2008-01-01

    The Space Telecommunications Radio System (STRS) Architecture Standard describes a standard for NASA space software defined radios (SDRs). It provides a common framework that can be used to develop and operate a space SDR in a reconfigurable and reprogrammable manner. One goal of the STRS Architecture is to promote waveform reuse among multiple software defined radios. Many space domain waveforms are designed to run in the special signal processing (SSP) hardware. However, the STRS Architecture is currently incomplete in defining a standard for designing waveforms in the SSP hardware. Therefore, the STRS Architecture needs to be extended to encompass waveform development in the SSP hardware. The extension of STRS to the SSP hardware will promote easier waveform reconfiguration and reuse. A transmit waveform for space applications was developed to determine ways to extend the STRS Architecture to a field programmable gate array (FPGA). These extensions include a standard hardware abstraction layer for FPGAs and a standard interface between waveform functions running inside a FPGA. A FPGA-based transmit waveform implementation of the proposed standard interfaces on a laboratory breadboard SDR will be discussed.

  12. The Climate Hazards group InfraRed Precipitation (CHIRP) with Stations (CHIRPS): Development and Validation

    NASA Astrophysics Data System (ADS)

    Peterson, P.; Funk, C. C.; Husak, G. J.; Pedreros, D. H.; Landsfeld, M.; Verdin, J. P.; Shukla, S.

    2013-12-01

    CHIRP and CHIRPS are new quasi-global precipitation products with daily to seasonal time scales, a 0.05° resolution, and a 1981 to near real-time period of record. Developed by the Climate Hazards Group at UCSB and scientists at the U.S. Geological Survey Earth Resources Observation and Science Center specifically for drought early warning and environmental monitoring, CHIRPS provides moderate latency precipitation estimates that place observed hydrologic extremes in their historic context. Three main types of information are used in the CHIRPS: (1) global 0.05° precipitation climatologies, (2) time-varying grids of satellite-based precipitation estimates, and (3) in situ precipitation observations. CHIRP: The global grids of long-term (1980-2009) average precipitation were estimated for each month based on station data, averaged satellite observations, and physiographic parameters. 1981-present time-varying grids of satellite precipitation were derived from spatially varying regression models based on pentadal cold cloud duration (CCD) values and TRMM V7 training data. The CCD time-series were derived from the CPC and NOAA B1 datasets. Pentadal CCD-percent anomaly values were multiplied by pentadal climatology fields to produce low bias pentadal precipitation estimates. CHIRPS: The CHG station blending procedure uses the satellite-observed spatial covariance structure to assign relative weights to neighboring stations and the CHIRP values. The CHIRPS blending procedure is based on the expected correlation between precipitation at a given target location and precipitation at the locations of the neighboring observation stations. These correlations are estimated using the CHIRP fields. The CHG has developed an extensive archive of in situ daily, pentadal and monthly precipitation totals. The CHG database has over half a billion daily rainfall observations since 1980 and another half billion before 1980. Most of these observations come from four sets of global climate observations: the monthly Global Historical Climate Network version 2 archive, the daily Global Historical Climate Network archive, the Global Summary of the Day dataset (GSOD), and the daily Global Telecommunication System (GTS) archive provided by NOAA's Climate Prediction Center (CPC). A screening procedure was developed to flag and remove potential false zeros from the daily data, since these potentially spurious data can artificially suppress rainfall totals. Validation: Our validation focused on precipitation products with global coverage, long periods of record and near real-time availability: CHIRP, CHIRPS, CPC-Unified, CFS Reanalysis and ECMWF datasets were compared to GPCC and high quality datasets from Uganda, Colombia and the Sahel. The CHIRP and CHIRPS are shown to have low systematic errors (bias) and low mean absolute errors. Analyses in Uganda, Colombia and the Sahel indicate that the ECMWF, CPC-Unified and CFS-Reanalysis have large inhomogeneities, making them unsuitable for drought monitoring. The CHIRPS performance appears quite similar to research quality products like the GPCC and GPCP, but with higher resolution and lower latency.

  13. Design constraints of optical parametric chirped pulse amplification based on chirped quasi-phase-matching gratings.

    PubMed

    Phillips, C R; Mayer, B W; Gallmann, L; Fejer, M M; Keller, U

    2014-04-21

    Chirped quasi-phase-matching (QPM) gratings offer efficient, ultra-broadband optical parametric chirped pulse amplification (OPCPA) in the mid-infrared as well as other spectral regions. Only recently, however, has this potential begun to be realized [1]. In this paper, we study the design of chirped QPM-based OPCPA in detail, revealing several important constraints which must be accounted for in order to obtain broad-band, high-quality amplification. We determine these constraints in terms of the underlying saturated nonlinear processes, and explain how they were met when designing our mid-IR OPCPA system. The issues considered include gain and saturation based on the basic three-wave mixing equations; suppression of unwanted non-collinear gain-guided modes; minimizing and characterizing nonlinear losses associated with random duty cycle errors in the QPM grating; avoiding coincidentally-phase-matched nonlinear processes; and controlling the temporal/spectral characteristics of the saturated nonlinear interaction in order to maintain the chirped-pulse structure required for OPCPA. The issues considered place constraints both on the QPM devices as well as the OPCPA system. The resulting experimental guidelines are detailed. Our results represent the first comprehensive discussion of chirped QPM devices operated in strongly nonlinear regimes, and provide a roadmap for advancing and experimentally implementing OPCPA systems based on these devices. PMID:24787850

  14. Mechanism of electron acceleration by chirped laser pulse

    SciTech Connect

    Wu, X. Y.; Wang, P. X. [Department of Nuclear Science and Technology, Institute of Modern Physics, Fudan University, Shanghai 200433, China and Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education (China); Kawata, S. [Department of Advanced Interdisciplinary Science, Center for Optical Research and Education, Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585 (Japan)

    2012-05-28

    We studied the mechanism of electron acceleration by a chirped laser pulse. We found that, because of the chirp effect, a region exists where the laser wave phase experienced by the electron varies slowly, so that the electron can be accelerated for a long time. The mechanism of chirped laser acceleration is different to that of the capture and acceleration scenario, although both of them have a main acceleration stage in which the electrons are trapped for long periods.

  15. 47 CFR 73.297 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false FM stereophonic sound broadcasting. 73.297 Section 73...Stations § 73.297 FM stereophonic sound broadcasting. (a) An FM broadcast...stereophonic (biphonic, quadraphonic, etc.) sound programs upon installation of...

  16. 47 CFR 73.297 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false FM stereophonic sound broadcasting. 73.297 Section 73...Stations § 73.297 FM stereophonic sound broadcasting. (a) An FM broadcast...stereophonic (biphonic, quadraphonic, etc.) sound programs upon installation of...

  17. 47 CFR 73.297 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false FM stereophonic sound broadcasting. 73.297 Section 73...Stations § 73.297 FM stereophonic sound broadcasting. (a) An FM broadcast...stereophonic (biphonic, quadraphonic, etc.) sound programs upon installation of...

  18. 47 CFR 73.297 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false FM stereophonic sound broadcasting. 73.297 Section 73...Stations § 73.297 FM stereophonic sound broadcasting. (a) An FM broadcast...stereophonic (biphonic, quadraphonic, etc.) sound programs upon installation of...

  19. Incoherent-light temporal stretching of high-speed intensity waveforms.

    PubMed

    Li, Bo; Azaña, José

    2014-07-15

    We propose and demonstrate experimentally the first incoherent-light scheme for temporal imaging (magnification) of intensity waveforms. The scheme is based on a time-domain equivalent of a pinhole camera under incoherent illumination, involving two dispersive lines and temporal intensity modulation with a short gate. We report incoherent-light temporal stretching of radiofrequency waveforms by a magnification factor of 2.86, with a time-bandwidth product exceeding 160, i.e., a resolution of ~50 ps over a temporal aperture of ~8 ns, totally avoiding the use of chirp-controlled pulsed lasers. This work opens up new perspectives for realization of many critical high-speed signal-processing modules using practical incoherent light-wave schemes. PMID:25121697

  20. Online waveform processing for demanding target situations

    NASA Astrophysics Data System (ADS)

    Pfennigbauer, Martin; Wolf, Clifford; Weinkopf, Josef; Ullrich, Andreas

    2014-06-01

    RIEGL LIDAR instruments are based on echo digitization and provide point cloud data by online waveform processing or full waveform data for external full waveform analysis or both. The advantages of online waveform processing of being fast and highly accurate for most typical target situation are made up by full waveform processing for demanding echo signal shapes when employing sophisticated algorithms. It is investigated how online waveform processing performs in turbid media and where the limitations are by analyzing experimental results when measuring in a fog chamber. An algorithm is proposed to determine the visibility range from the echo waveforms return of the medium.

  1. STRS Compliant FPGA Waveform Development

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer; Downey, Joseph

    2008-01-01

    The Space Telecommunications Radio System (STRS) Architecture Standard describes a standard for NASA space software defined radios (SDRs). It provides a common framework that can be used to develop and operate a space SDR in a reconfigurable and reprogrammable manner. One goal of the STRS Architecture is to promote waveform reuse among multiple software defined radios. Many space domain waveforms are designed to run in the special signal processing (SSP) hardware. However, the STRS Architecture is currently incomplete in defining a standard for designing waveforms in the SSP hardware. Therefore, the STRS Architecture needs to be extended to encompass waveform development in the SSP hardware. A transmit waveform for space applications was developed to determine ways to extend the STRS Architecture to a field programmable gate array (FPGA). These extensions include a standard hardware abstraction layer for FPGAs and a standard interface between waveform functions running inside a FPGA. Current standards were researched and new standard interfaces were proposed. The implementation of the proposed standard interfaces on a laboratory breadboard SDR will be presented.

  2. LIABILITY INSURANCE University Policy No: FM5300

    E-print Network

    Victoria, University of

    1 LIABILITY INSURANCE University Policy No: FM5300 Classification: Financial Management Approving, its officers, employees, volunteers and certain other named insureds, Comprehensive General Liability, Errors and Omissions and other insurance policies. These policies contain certain exclusions requiring

  3. Polyphase-Coded FM Waveform Optimization within a LINC Transmit Architecture

    E-print Network

    Ryan, Lane

    2014-05-31

    and at the end of the pulse is still well defined. 31 0 1 2 3 4 5 6 -40 -20 0 Time(us) A m p l i t u d e ( d B ) 0 1 2 3 4 5 6 0 0.5 1 Time(us) N o r m a l i z e d A m p l i t u d e Received Reference Received Reference Figure 5.9. Amplitude... -30 -20 -10 0 Normalized Pulse Width P o w e r ( d B ) LFM Sim w/o hardware opt Figure 5.17. LFM and simulation optimized PCFM 40 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 -60 -50 -40 -30 -20 -10 0 Normalized Pulse Width P o w e r ( d B...

  4. Point Response Characteristics for the CERES/EOS-PM, FM3 & FM4 instruments.

    NASA Technical Reports Server (NTRS)

    Paden, Jack; Smith, G. Louis; Lee, Robert B., III; Pandey, Dhirendra K.; Priestley, Kory J.; Thomas, Susan; Wilson, Robert S.

    1999-01-01

    This paper describes the point source functions (PSF s) of the Clouds and the Earth s Radiant Energy System (CERES,) Earth Observing System (EOS,) afternoon platform (PM,) Flight Model 3 (FM3,) and Flight Model 4 (FM4) scanning instruments. The PSF (also known as the Point Response Function, or PRF) is vital to the accurate geo-location of the remotely sensed radiance measurements acquired by the instrument. This paper compares the characteristics of the FM3 and FM4 instruments with the earlier Proto Flight Model (PFM) on the Tropical Rainfall Measuring Mission (TRMM) platform, and the FM1 and FM2 Models on the EOS morning orbiting (AM) platform, which has recently been renamed "Terra". All of the PSF s were found to be quite comparable, and the previously noted "spreading" characteristic of the window (water vapor) channel PSF is analyzed Keywords: PSF, PRF, CERES, TRMM, EOS, Earth Radiation Budget

  5. Interfacing AM/FM with distribution SCADA

    SciTech Connect

    Horton, M.A. (Union Electric Co., St. Louis, MO (United States))

    1993-01-01

    This article examines an upgrade to Union Electric's (UE's) distribution SCADA system by interfacing it with UE's automated mapping and facility management (AM/FM) system to give dispatchers a way to relate facility outages geographically with a real-time monitoring system. The topics of the article are the original SCADA system, the AM/FM system, and the new SCADA system, the man-machine and machine-machine interface, and further applications.

  6. SCADA -- AM/FM interface: Platforms, technology

    SciTech Connect

    Gilbert, R.F. (Valmet, Automation, Inc., Houston, TX (United States))

    1994-05-01

    Efficient utility operations is enhanced by close interoperation between automated mapping/facility management (AM/FM) and supervisory control and data acquisition (SCADA) systems. Important benefits of such integration are improvements in service quality and reduced maintenance costs. Development of an AM/FM -- SCADA interface to provide automatic database and display generation for SCADA through AM/FM functions is continuing by Valmet Automation. To minimize or eliminate vendor-dependence, the AM/FM-SCADA interface is compliant with the Electric Power Research Institute's (EPRI) utility communication architecture (UCA). The utility industry is changing at an unprecedented rate. To remain a leader, or even to keep pace, utilities must be flexible and innovative. Competition forces companies to become more streamlined and efficient. These forces make the requirements for automation go beyond simple SCADA. Among several developing trends in the industry is the emergence of AM/FM. Collectively, these trends indicate the need to increase efficiency in the design, operation and maintenance of the transmission and distribution system. To accomplish its mission, SCADA and AM/FM must be a highly integrated system to provide timely information to its users. Open systems, the client-server paradigm and better information integration tools facilitate meeting these needs. UCA specification provides the technological glue, to achieve application integration between heterogeneous systems.

  7. Chirp characteristics of silicon Mach-Zehnder modulators

    Microsoft Academic Search

    Yuxin Wei; Yong Zhao; Guoyi Li; Jianyi Yang; Minghua Wang; Xiaoqing Jiang

    2010-01-01

    Chirp characteristics of silicon based Mach-Zehnder-interferometer (MZI) modulators with PIN diode and PN diode are fully analyzed, respectively. Simulation result shows that the chirp parameter is negative and influenced by the carrier absorption effect, the amplitude and frequency of applied sinusoidal modulating signals

  8. Chirped optical solitons in single-mode birefringent fibers

    NASA Astrophysics Data System (ADS)

    Mahmood, M. F.

    1996-12-01

    The trapping behavior of two chirped solitons forming a bound state in a single-mode birefringent fiber is investigated on the basis of a model of coupled nonlinear Schroedinger equations. The positive initial chirp plays an important role in controlling the threshold amplitude for soliton trapping without causing excessive pulse broadening.

  9. Chirp on Crickets: Teaching Compilers Using an Embedded Robot Controller

    E-print Network

    Chirp on Crickets: Teaching Compilers Using an Embedded Robot Controller Li Xu Department into the simple yet versatile Handy Cricket educational robot con- troller. As a compiler, the Chirp design with code generation for the Cricket controller. They will test their work on both phys- ical Cricket

  10. Hyperspectral Imaging with Stimulated Raman Scattering by Chirped Femtosecond Lasers

    E-print Network

    Xie, Xiaoliang Sunney

    Hyperspectral Imaging with Stimulated Raman Scattering by Chirped Femtosecond Lasers Dan Fu, Gary imaging system using chirped femtosecond lasers to achieve rapid Raman spectra acquisition while retaining laser beams with an energy difference tuned to the vibrational frequency of the molecule of interest

  11. Chirp: a practical global filesystem for cluster and Grid computing

    Microsoft Academic Search

    Douglas Thain; Christopher Moretti; Jeffrey Hemmes

    2009-01-01

    Traditional distributed £lesystem technologies designed for local and campus area networks do not adapt well to wide area grid computing environments. To address this problem, we have designed the Chirp distributed £lesystem, which is designed from the ground up to meet the needs of grid computing. Chirp is easily deployed without special privileges, provides strong andexible security mechanisms, tunable consistency

  12. Waveform-dependent absorbing metasurfaces.

    PubMed

    Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2013-12-13

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW's), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications. PMID:24483674

  13. Waveform-dependent absorbing metasurfaces

    E-print Network

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2014-01-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  14. Chirped fiber Bragg grating detonation velocity sensing

    NASA Astrophysics Data System (ADS)

    Rodriguez, G.; Sandberg, R. L.; McCulloch, Q.; Jackson, S. I.; Vincent, S. W.; Udd, E.

    2013-01-01

    An all optical-fiber-based approach to measuring high explosive detonation front position and velocity is described. By measuring total light return using an incoherent light source reflected from a linearly chirped fiber Bragg grating sensor in contact with the explosive, dynamic mapping of the detonation front position and velocity versus time is obtained. We demonstrate two calibration procedures and provide several examples of detonation front measurements: PBX 9502 cylindrical rate stick, radial detonation front in PBX 9501, and PBX 9501 detonation along curved meridian line. In the cylindrical rate stick measurement, excellent agreement with complementary diagnostics (electrical pins and streak camera imaging) is achieved, demonstrating accuracy in the detonation front velocity to below the 0.3% level when compared to the results from the pin data. Finally, an estimate on the linear spatial and temporal resolution of the system shows that sub-mm and sub-?s levels are attainable with proper consideration of the recording speed, detection sensitivity, spectrum, and chirp properties of the grating.

  15. Chirped fiber Bragg grating detonation velocity sensing.

    PubMed

    Rodriguez, G; Sandberg, R L; McCulloch, Q; Jackson, S I; Vincent, S W; Udd, E

    2013-01-01

    An all optical-fiber-based approach to measuring high explosive detonation front position and velocity is described. By measuring total light return using an incoherent light source reflected from a linearly chirped fiber Bragg grating sensor in contact with the explosive, dynamic mapping of the detonation front position and velocity versus time is obtained. We demonstrate two calibration procedures and provide several examples of detonation front measurements: PBX 9502 cylindrical rate stick, radial detonation front in PBX 9501, and PBX 9501 detonation along curved meridian line. In the cylindrical rate stick measurement, excellent agreement with complementary diagnostics (electrical pins and streak camera imaging) is achieved, demonstrating accuracy in the detonation front velocity to below the 0.3% level when compared to the results from the pin data. Finally, an estimate on the linear spatial and temporal resolution of the system shows that sub-mm and sub-?s levels are attainable with proper consideration of the recording speed, detection sensitivity, spectrum, and chirp properties of the grating. PMID:23387683

  16. Oral thrombostatin FM19 inhibits prostate cancer.

    PubMed

    Nieman, Marvin T; LaRusch, Gretchen; Fang, Chao; Zhou, Yihua; Schmaier, Alvin H

    2010-11-01

    Thrombin stimulates proliferation, invasion and metastasis by cleaving protease-activated receptor 1 (PAR1) on human prostate cancer cells. Current direct thrombin inhibitors pose risks for bleeding in the cancer patients. We have developed an oral reversible direct thrombin inhibitor called FM19. FM19 inhibits thrombin-induced calcium mobilisation of PC3 cells with an IC50 of 15 ?M with a 95% confidence interval of 7.3-31.6 ?M. Thrombin stimulation increases PC3 cell invasion three-fold from 27.1 ± 11.4 to 66 ± 11.6. FM19 or bivalirudin reduces cell invasion at ?0.1 ?M (p?0.02). After inoculation with PC3 cells, nude mice were treated with oral FM19 at 3 mg/ml in the drinking water. The treated mice did not have long bleeding times and only a 1.4-fold increase in their thrombin clotting time. However, with treatment, the mice have a reduced rate of tumour growth 0.26 ± 0.17 fold change/day vs. 0.55 ± 0.35 for untreated (p = 0.038), reduced fold change in tumour size 5.3 ± 0.47 to 8.9 ± 1.8 (untreated) (p=0.048), and reduced overall tumour weight 0.5 ± 0.31 g vs. 0.82 ± 0.32 g (untreated) (p=0.04). On microscopic examination, FM19 treatment reduces the number of large vessels in the tumours from 4.6 ± 2.1 per high-powered field in untreated samples to 1.4 ± 1.4 in treated samples (p?0.04). These studies show FM19 reduces prostate tumour growth in vivo at a concentration below that needed for anticoagulation. These data suggest novel opportunities for oral direct thrombin inhibitors in cancer therapy. PMID:20886199

  17. Frequency specificity of chirp-evoked auditory brainstem responses

    NASA Astrophysics Data System (ADS)

    Wegner, Oliver; Dau, Torsten

    2002-03-01

    This study examines the usefulness of the upward chirp stimulus developed by Dau et al. [J. Acoust. Soc. Am. 107, 1530-1540 (2000)] for retrieving frequency-specific information. The chirp was designed to produce simultaneous displacement maxima along the cochlear partition by compensating for frequency-dependent traveling-time differences. In the first experiment, auditory brainstem responses (ABR) elicited by the click and the broadband chirp were obtained in the presence of high-pass masking noise, with cutoff frequencies of 0.5, 1, 2, 4, and 8 kHz. Results revealed a larger wave-V amplitude for chirp than for click stimulation in all masking conditions. Wave-V amplitude for the chirp increased continuously with increasing high-pass cutoff frequency while it remains nearly constant for the click for cutoff frequencies greater than 1 kHz. The same two stimuli were tested in the presence of a notched-noise masker with one-octave wide spectral notches corresponding to the cutoff frequencies used in the first experiment. The recordings were compared with derived responses, calculated offline, from the high-pass masking conditions. No significant difference in response amplitude between click and chirp stimulation was found for the notched-noise responses as well as for the derived responses. In the second experiment, responses were obtained using narrow-band stimuli. A low-frequency chirp and a 250-Hz tone pulse with comparable duration and magnitude spectrum were used as stimuli. The narrow-band chirp elicited a larger response amplitude than the tone pulse at low and medium stimulation levels. Overall, the results of the present study further demonstrate the importance of considering peripheral processing for the formation of ABR. The chirp might be of particular interest for assessing low-frequency information.

  18. Chirped pulse amplification in single mode Tm:fiber using a chirped Bragg grating

    NASA Astrophysics Data System (ADS)

    Sims, R. Andrew; Kadwani, Pankaj; Ebendorff-Heideprem, Heike; Shah, Lawrence; Monro, Tanya M.; Richardson, Martin

    2013-05-01

    We report femtosecond pulse generation and chirped pulse amplification in Tm:fiber. A mode-locked oscillator operating in the soliton regime produced 800 fs pulses with 5 nm spectral bandwidth, at 40 pJ pulse energy. This oscillator seeded a pre-amplifier that utilizes a Raman soliton self-frequency shift to produce wavelength tunable pulses with 3 nJ energy, reduced pulse duration of 150 fs, and increased bandwidth of 30 nm. For further amplification, the pulses were stretched up to 160 ps using a chirped Bragg grating (CBG). Stretched pulses were amplified to 85 nJ after compression in single-mode Tm:fiber and recompressed with the CBG as short as 400 fs. Compressed pulses were coupled into a highly nonlinear tellurite fiber to investigate the potential of this ultrashort pulse 2-?m fiber source as a pump for mid-IR supercontinuum generation.

  19. Multiterawatt laser system based on optical parametric chirped pulse amplification.

    PubMed

    Yang, Xiaodong; Xu, Zhi-Zhan; Leng, Yu-Xin; Lu, Hai-He; Lin, Li-Huang; Zhang, Zheng-Quan; Li, Ru-Xin; Zhang, Wen-Qi; Yin, Ding-Jun; Tang, Bing

    2002-07-01

    A compact multiterawatt laser system based on optical parametric chirped pulse amplification is demonstrated. Chirped pulses are amplified from 20 pJ to 900 mJ by two lithium triborate optical parametric preamplifiers and a final KDP optical parametric power amplifier with a pump energy of 5 J at 532 nm from Nd:YAG-Nd:glass hybrid amplifiers. After compression, we obtained a final output of 570-mJ-155-fs pulses with a peak power of 3.67 TW, which is the highest output power from an optical parametric chirped pulse amplification laser, to the best of our knowledge. PMID:18026385

  20. Three-Dimensional Analysis of Frequency-Chirped FELs

    SciTech Connect

    Huang, Z.

    2010-09-14

    Frequency-chirped free-electron lasers (FELs) are useful to generate a large photon bandwidth or a shorter x-ray pulse duration. In this paper, we present a three-dimensional analysis of a high-gain FEL driven by the energy-chirped electron beam. We show that the FEL eigenmode equation is the same for a frequency-chirped FEL as for an undulator-tapered FEL. We study the transverse effects of such FELs including mode properties and transverse coherence.

  1. High-precision triangular-waveform generator

    Microsoft Academic Search

    1981-01-01

    An ultra-linear ramp generator having separately programmable ascending and decending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by

  2. Chirped-Superlattice, Blocked-Intersubband QWIP

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath; Ting, David; Bandara, Sumith

    2004-01-01

    An Al(x)Ga(1-x)As/GaAs quantum-well infrared photodetector (QWIP) of the blocked-intersubband-detector (BID) type, now undergoing development, features a chirped (that is, aperiodic) superlattice. The purpose of the chirped superlattice is to increase the quantum efficiency of the device. A somewhat lengthy background discussion is necessary to give meaning to a brief description of the present developmental QWIP. A BID QWIP was described in "MQW Based Block Intersubband Detector for Low-Background Operation" (NPO-21073), NASA Tech Briefs Vol. 25, No. 7 (July 2001), page 46. To recapitulate: The BID design was conceived in response to the deleterious effects of operation of a QWIP at low temperature under low background radiation. These effects can be summarized as a buildup of space charge and an associated high impedance and diminution of responsivity with increasing modulation frequency. The BID design, which reduces these deleterious effects, calls for a heavily doped multiple-quantum-well (MQW) emitter section with barriers that are thinner than in prior MQW devices. The thinning of the barriers results in a large overlap of sublevel wave functions, thereby creating a miniband. Because of sequential resonant quantum-mechanical tunneling of electrons from the negative ohmic contact to and between wells, any space charge is quickly neutralized. At the same time, what would otherwise be a large component of dark current attributable to tunneling current through the whole device is suppressed by placing a relatively thick, undoped, impurity-free AlxGa1 x As blocking barrier layer between the MQW emitter section and the positive ohmic contact. [This layer is similar to the thick, undoped Al(x)Ga(1-x)As layers used in photodetectors of the blocked-impurity-band (BIB) type.] Notwithstanding the aforementioned advantage afforded by the BID design, the responsivity of a BID QWIP is very low because of low collection efficiency, which, in turn, is a result of low electrostatic- potential drop across the superlattice emitter. Because the emitter must be electrically conductive to prevent the buildup of space charge in depleted quantum wells, most of the externally applied bias voltage drop occurs across the blocking-barrier layer. This completes the background discussion. In the developmental QWIP, the periodic superlattice of the prior BID design is to be replaced with the chirped superlattice, which is expected to provide a built-in electric field. As a result, the efficiency of collection of photoexcited charge carriers (and, hence, the net quantum efficiency and thus responsivity) should increase significantly.

  3. FY05 FM Dial Summary Report

    SciTech Connect

    Harper, Warren W.; Strasburg, Jana D.; Golovich, Elizabeth C.; Thompson, Jason S.; Stewart, Timothy L.; Batdorf, Michael T.

    2005-12-01

    Pacific Northwest National Laboratory's Infrared Sensors team is focused on developing methods for standoff detection of nuclear proliferation. In FY05, PNNL continued the development of the FM DIAL (frequency-modulated differential absorption LIDAR) experiment. Additional improvements to the FM DIAL trailer provided greater stability during field campaigns which made it easier to explore new locations for field campaigns. In addition to the Hanford Townsite, successful experiments were conducted at the Marine Science Laboratory in Sequim, WA and the Nevada Test Site located outside Las Vegas, NV. The range of chemicals that can be detected by FM DIAL has also increased. Prior to FY05, distributed feedback quantum cascade lasers (DFB-QCL) were used in the FM DIAL experiments. With these lasers, only simple chemicals with narrow (1-2 cm-1) absorption spectra, such as CO2 and N2O, could be detected. Fabry-Perot (FP) QC lasers have much broader spectra (20-40 cm-1) which allows for the detection of larger chemicals and a wider array of chemicals that can be detected. A FP-QCL has been characterized and used during initial studies detecting DMMP (dimethyl methylphosphonate).

  4. Enlightening News and Views FM Employees

    E-print Network

    Oyet, Alwell

    they have put into the design and construction of this display. The Better Work Supervisor Tip: Be a good coach. Instead of telling people what to do, mentor them so they can do it themselves. #12;FM Light 2 parents of their first child, a baby boy. Jack Allan was born in March 2008 at 9 lbs. Mom is back to work

  5. Enlightening News and Views FM Employees

    E-print Network

    deYoung, Brad

    #12;FM Light 2 Community Garden Interested in having your own plot at the Memorial University Community Garden this year? Deadline for applications is Friday, March 25, 2011. Current Memo- rial students in touch with what's happening at the garden, join the Community Garden mailing list by sending an e

  6. > RADIO TUDIANTE CISM 89,3 FM

    E-print Network

    Charette, André

    3 0 > RADIO �TUDIANTE ­ CISM 89,3 FM Pavillon J.-A.-DeSève 2332, boul. �douard-Montpetit Local C@pol.umontreal.ca Revue du Département de science politique de l'UdeM. Radio > ATELIERS DE FORMATION EN RADIO (ACTIVIT�S

  7. Determining the response of an FM receiver

    NASA Technical Reports Server (NTRS)

    Perry, J. C.

    1979-01-01

    Frequency response to frequency-modulation (FM) receiver is measured with aid of phase-modulation (PM) transmitter by applying correction to output power level. As modulating frequency is increased, output level obtained in response to PM input is reduced by 6 db per octane.

  8. HOSPITALITY EXPENDITURE University Policy No: FM5600

    E-print Network

    Herwig, Falk

    .00 The purpose of this policy is to ensure that Hospitality expenditures paid by the university are managedPage 1 HOSPITALITY EXPENDITURE POLICY University Policy No: FM5600 Classification: Financial Management Approving authority: Vice-President Finance and Operations Effective date: September, 2012

  9. Dispersion compensation in chirped pulse amplification systems

    DOEpatents

    Bayramian, Andrew James; Molander, William A.

    2014-07-15

    A chirped pulse amplification system includes a laser source providing an input laser pulse along an optical path. The input laser pulse is characterized by a first temporal duration. The system also includes a multi-pass pulse stretcher disposed along the optical path. The multi-pass pulse stretcher includes a first set of mirrors operable to receive input light in a first plane and output light in a second plane parallel to the first plane and a first diffraction grating. The pulse stretcher also includes a second set of mirrors operable to receive light diffracted from the first diffraction grating and a second diffraction grating. The pulse stretcher further includes a reflective element operable to reflect light diffracted from the second diffraction grating. The system further includes an amplifier, a pulse compressor, and a passive dispersion compensator disposed along the optical path.

  10. Chirped pulse amplification: Present and future

    SciTech Connect

    Maine, P.; Strickland, D.; Pessot, M.; Squier, J.; Bado, P.; Mourou, G.; Harter, D.

    1988-01-01

    Short pulses with ultrahigh peak powers have been generated in Nd: glass and Alexandrite using the Chirped Pulse Amplification (CPA) technique. This technique has been successful in producing picosecond terawatt pulses with a table-top laser system. In the near future, CPA will be applied to large laser systems such as NOVA to produce petawatt pulses (1 kJ in a 1 ps pulse) with focused intensities exceeding 10/sup /plus/21/ W/cm/sup 2/. These pulses will be associated with electric fields in excess of 100 e/a/sub o//sup 2/ and blackbody energy densities equivalent to 3 /times/ 10/sup 10/ J/cm/sup 3/. This petawatt source will have important applications in x-ray laser research and will lead to fundamentally new experiments in atomic, nuclear, solid-state, plasma, and high-energy density physics. A review of present and future designs are discussed. 17 refs., 5 figs.

  11. Quantum Fluctuations in the Chirped Pendulum

    E-print Network

    K. W. Murch; R. Vijay; I. Barth; O. Naaman; J. Aumentado; L. Friedland; I. Siddiqi

    2010-08-26

    An anharmonic oscillator when driven with a fast, frequency chirped voltage pulse can oscillate with either small or large amplitude depending on whether the drive voltage is below or above a critical value-a well studied classical phenomenon known as autoresonance. Using a 6 GHz superconducting resonator embedded with a Josephson tunnel junction, we have studied for the first time the role of noise in this non-equilibrium system and find that the width of the threshold for capture into autoresonance decreases as the square root of T, and saturates below 150 mK due to zero point motion of the oscillator. This unique scaling results from the non-equilibrium excitation where fluctuations, both quantum and classical, only determine the initial oscillator motion and not its subsequent dynamics. We have investigated this paradigm in an electrical circuit but our findings are applicable to all out of equilibrium nonlinear oscillators.

  12. Versatile Dual-Channel Waveform Generator

    NASA Technical Reports Server (NTRS)

    Staples, Edward J.; Lie, Sen; Ching, Michael; Budinger, James M.

    1994-01-01

    Programmable waveform generator synthesizes two independent waveforms simultaneously at frequencies up to 250 MHz. Can be in phase or out of phase with each other. Use of commercial integrated circuits helps keep cost low. Operation governed by BASIC source code enabling any user equipped with suitable personal computer to specify waveforms. User can modify source code to satisfy special needs. Other applications include simulation of Doppler waveforms for radar, and of video signals for testing color displays and computer monitors. With eventual substitution of gallium arsenide integrated circuits for its present silicon integrated circuits, instrument able to generate waveforms with 14-bit precision and sample rates as high as 2 GHz.

  13. Sinewave parameter estimation using the fast fan-chirp transform

    E-print Network

    Dunn, Robert B.

    Sinewave analysis/synthesis has long been an important tool for audio analysis, modification and synthesis. The recently introduced fan-chirp Transform (FChT) [2,3] has been shown to improve the fidelity of sinewave parameter ...

  14. Iterative direction-of-arrival estimation with wideband chirp signals

    NASA Astrophysics Data System (ADS)

    Wang, Genyuan; Xia, Xiang-Gen; Chen, Victor C.

    1999-11-01

    Amin et. al. recently developed a time-frequency MUSIC algorithm with narrow band models for the estimation of direction of arrival (DOA) when the source signals are chirps. In this research, we consider wideband models. The joint time-frequency analysis is first used to estimate the chirp rates of the source signals and then the DOA is estimated by the MUSIC algorithm with an iterative approach.

  15. Automated Analysis, Classification, and Display of Waveforms

    NASA Technical Reports Server (NTRS)

    Kwan, Chiman; Xu, Roger; Mayhew, David; Zhang, Frank; Zide, Alan; Bonggren, Jeff

    2004-01-01

    A computer program partly automates the analysis, classification, and display of waveforms represented by digital samples. In the original application for which the program was developed, the raw waveform data to be analyzed by the program are acquired from space-shuttle auxiliary power units (APUs) at a sampling rate of 100 Hz. The program could also be modified for application to other waveforms -- for example, electrocardiograms. The program begins by performing principal-component analysis (PCA) of 50 normal-mode APU waveforms. Each waveform is segmented. A covariance matrix is formed by use of the segmented waveforms. Three eigenvectors corresponding to three principal components are calculated. To generate features, each waveform is then projected onto the eigenvectors. These features are displayed on a three-dimensional diagram, facilitating the visualization of the trend of APU operations.

  16. Sampled chirped fiber gratings as distributed pressure sensors

    NASA Astrophysics Data System (ADS)

    Tjin, Swee Chuan; Mohanty, Lipi; Ngo, Nam Quoc

    2004-09-01

    Fiber gratings have been studied for their applications in sensing and communications. Many sensing applications of the uniform fiber Bragg grating, chirped fiber grating and long period grating have been studied, proposed and commercialized. Sampled chirped gratings have been studied for multichannel dispersion compensation in DWDM systems. In this paper, we show that the sampled chirped fiber grating can be used as a distributed pressure sensor. The chirp provides ease of manufacture of many gratings. The sampling results in many small, uniform grating-like structures. This fact can be used to simulate a distributed sensor over the length of the sampled chirped grating. When a surface comes into contact with the sensor, the distribution of the pressure determines the shift in central wavelength of the various sub-gratings. The sub-grating that experiences the maximum pressure will show maximum wavelength shift whereas adjacent sub-gratings will show less shift. This can also give the location of the pressure. The sensor design comprises of a sampled chirped grating embedded in unidirectional fiber-reinforced composite prepreg. The prepreg enhances the mechanical strength and the unidirectional embedding reduces birefringence. The number of layers in the prepreg stack varies the sensitivity. Such distributed pressure sensors can be applied in robotics, ergonomics, and in the biomedical field.

  17. 47 CFR 73.597 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false FM stereophonic sound broadcasting. 73.597 Section 73...Stations § 73.597 FM stereophonic sound broadcasting. A noncommercial educational...authority from the FCC, transmit stereophonic sound programs upon installation of...

  18. 47 CFR 73.322 - FM stereophonic sound transmission standards.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false FM stereophonic sound transmission standards. 73.322 Section...Stations § 73.322 FM stereophonic sound transmission standards. (a) An...one channel of a two channel (biphonic) sound transmission, modulation of the...

  19. 47 CFR 73.322 - FM stereophonic sound transmission standards.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false FM stereophonic sound transmission standards. 73.322 Section...Stations § 73.322 FM stereophonic sound transmission standards. (a) An...one channel of a two channel (biphonic) sound transmission, modulation of the...

  20. 47 CFR 73.597 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false FM stereophonic sound broadcasting. 73.597 Section 73...Stations § 73.597 FM stereophonic sound broadcasting. A noncommercial educational...authority from the FCC, transmit stereophonic sound programs upon installation of...

  1. 47 CFR 73.597 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false FM stereophonic sound broadcasting. 73.597 Section 73...Stations § 73.597 FM stereophonic sound broadcasting. A noncommercial educational...authority from the FCC, transmit stereophonic sound programs upon installation of...

  2. 47 CFR 73.597 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false FM stereophonic sound broadcasting. 73.597 Section 73...Stations § 73.597 FM stereophonic sound broadcasting. A noncommercial educational...authority from the FCC, transmit stereophonic sound programs upon installation of...

  3. 47 CFR 73.597 - FM stereophonic sound broadcasting.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false FM stereophonic sound broadcasting. 73.597 Section 73...Stations § 73.597 FM stereophonic sound broadcasting. A noncommercial educational...authority from the FCC, transmit stereophonic sound programs upon installation of...

  4. 47 CFR 73.322 - FM stereophonic sound transmission standards.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false FM stereophonic sound transmission standards. 73.322 Section...Stations § 73.322 FM stereophonic sound transmission standards. (a) An...one channel of a two channel (biphonic) sound transmission, modulation of the...

  5. 47 CFR 73.322 - FM stereophonic sound transmission standards.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false FM stereophonic sound transmission standards. 73.322 Section...Stations § 73.322 FM stereophonic sound transmission standards. (a) An...one channel of a two channel (biphonic) sound transmission, modulation of the...

  6. 47 CFR 73.322 - FM stereophonic sound transmission standards.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...false FM stereophonic sound transmission standards...322 FM stereophonic sound transmission standards...the stereophonic pilot frequency in a transmission system...19 kHz ±2 Hz, must frequency modulate the main carrier...channel (biphonic) sound transmission,...

  7. DistillationTheory.fm 2 September 1999 Distillation Theory.

    E-print Network

    Skogestad, Sigurd

    1 DistillationTheory.fm 2 September 1999 Distillation Theory. by Ivar J. Halvorsen and Sigurd, Norway #12;2 DistillationTheory.fm 2 September 1999 Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Material Balance on a Distillation Stage

  8. A modified adaptive algorithm of dealing with the high chirp when chirped pulses propagating in optical fiber

    NASA Astrophysics Data System (ADS)

    Wu, Lianglong; Fu, Xiquan; Guo, Xing

    2013-03-01

    In this paper, we propose a modified adaptive algorithm (MAA) of dealing with the high chirp to efficiently simulate the propagation of chirped pulses along an optical fiber for the propagation distance shorter than the "temporal focal length". The basis of the MAA is that the chirp term of initial pulse is treated as the rapidly varying part by means of the idea of the slowly varying envelope approximation (SVEA). Numerical simulations show that the performance of the MAA is validated, and that the proposed method can decrease the number of sampling points by orders of magnitude. In addition, the computational efficiency of the MAA compared with the time-domain beam propagation method (BPM) can be enhanced with the increase of the chirp of initial pulse.

  9. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 4 2012-10-01 2012-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  10. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 4 2011-10-01 2011-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  11. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 4 2014-10-01 2014-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  12. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 4 2010-10-01 2010-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  13. 47 CFR 73.599 - NCE-FM engineering charts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 4 2013-10-01 2013-10-01 false NCE-FM engineering charts. 73.599 Section 73.599 Telecommunication...Educational FM Broadcast Stations § 73.599 NCE-FM engineering charts. This section consists of the following...

  14. Modulate Internet Radio Into FM Using GNU Radio

    E-print Network

    Yu, Chansu

    1 Modulate Internet Radio Into FM Using GNU Radio By: Elie Salameh Outline. · Fm in gnu radio · Audio Streams in Internet Radio · Gnu & Audio Files · Sox command · Playlist ".pls" · Recording internet radio #12;2 Project description · Using gnu radio to modulate internet radio into fm. · Using usrp

  15. Improved performance of coded digital FM

    Microsoft Academic Search

    R. F. Pawula

    1999-01-01

    The performance of convolutionally encoded narrow-band digital FM with Viterbi decoding was considered in some detail by Simon (1983) for a noncoherent limiter\\/discriminator (L\\/D) with integrate and dump (I&D) bit detection. Employing a new threshold receiver which averages the output of the I&D detector with the output of a sample and hold (S&H) detector, a 3-dB improvement over Simon's results

  16. Interfacing AM\\/FM with distribution SCADA

    Microsoft Academic Search

    M. A. Horton

    1993-01-01

    Union Electric Company (UE) decided to upgrade its existing distribution SCADA system and improve dispatching\\/operating efficiencies by interfacing it with UE's automated mapping and facility management (AM\\/FM) system, thus giving the dispatchers a way to relate facility outages geographically with a real-time monitoring system. This interfaced system will improve the efficiency in the management of UE's power distribution and the

  17. FD-CHIRP: hosted payload system engineering lessons

    NASA Astrophysics Data System (ADS)

    Schueler, Carl F.

    2012-10-01

    The Commercially Hosted Infrared Payload (CHIRP) Flight Demonstration (FD-CHIRP) launched 21 Sept 2011 was designated a "resounding success" as the first Wide Field-of-View (WFOV) staring infrared (IR) sensor flown in geostationary earth orbit (GEO) with a primary mission of Missile Warning (MW). FD-CHIRP was an Air Force research and development project initiated in July 2008 via an unsolicited industry proposal aimed to mature and reduce the risk of WFOV sensors and ground processing technologies. Unlike the Defense Support Program (DSP) and the Space Based Infrared System (SBIRS) which were acquired via traditional integrated sensor and satellite design, FDCHIRP was developed using the "commercially hosted" approach. The FD-CHIRP host spacecraft and sensor were independently designed, creating significant development risk to the industry proposer, especially under a Firm Fixed Price contract. Yet, within 39 months of contract initiation, FD-CHIRP was launched and successfully operated in GEO to 30 June 2012 at a total cost of 111M including the 82.9M CHIRP commercial-hosting contract and a $28M sensor upgrade. The commercial-hosting contract included sensor and spacecraft modifications, integration and test, design and development of secure Mission Operations and Analysis Centers, launch, and nearly a year of GEO operations with 70 Mbps secure data acquisition. The Air Force extended the contract for six months to continue operations through the end of calendar 2012. This paper outlines system engineering challenges FD-CHIRP overcame and key lessons to smooth development of future commercially hosted missions.

  18. A chirped photonic-crystal fibre

    NASA Astrophysics Data System (ADS)

    Skibina, Julia S.; Iliew, Rumen; Bethge, Jens; Bock, Martin; Fischer, Dorit; Beloglasov, Valentin I.; Wedell, Reiner; Steinmeyer, Günter

    2008-11-01

    Photonic crystals have widely increased the facility to guide and confine light at wavelengths close to the optical wavelength. Because they can include extremely sharp bends, photonic-crystal waveguides are a key element in future integrated optical devices. Moreover, they enable the manipulation of the spontaneous emission properties of luminescent devices, the localization of light in microcavities, and they may serve to generate negative refraction. A special class of these devices are the hollow-core photonic-crystal fibres, which confine the light by means of a periodic cladding, consisting of several layers of identical cells. This design resonantly decreases the transmission losses of such fibres to values of a few dB km-1 in a narrow wavelength range. However, the rather narrowband transmission bands and the detrimental third-order dispersion characteristics of this single-cell design generally render application of such hollow-core fibres difficult in the femtosecond range. Therefore, no fibre-based concept can currently provide guiding of sub-100 fs pulses over extended distances. By introducing a radial chirp into the photonic crystal, we here demonstrate a novel concept for photonic-crystal fibres that breaks with the paradigm of lattice homogeneity and enables a new degree of freedom in photonic-crystal-fibre design, eliminating much of the pulse duration restriction of earlier approaches.

  19. High-precision triangular-waveform generator

    DOEpatents

    Mueller, T.R.

    1981-11-14

    An ultra-linear ramp generator having separately programmable ascending and decending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  20. Asymptotic Properties of the Least Squares Estimators of the Parameters of the Chirp Signals

    E-print Network

    Kundu, Debasis

    of Technology Kanpur Kanpur, Pin 208016 India Abstract: Chirp signals are quite common in different areas rejection is important chirp signals provide a successful digital modulation scheme. For instance, consider

  1. Sectional chirped volume Bragg grating compressors for high-power chirped-pulse amplification

    NASA Astrophysics Data System (ADS)

    Andrusyak, Oleksiy; Canioni, Lionel; Cohanoshi, Ion; Delaigue, Martin; Rotari, Eugeniu; Smirnov, Vadim; Glebov, Leonid

    2010-02-01

    Chirped Bragg Gratings (CBGs) recorded in photo-thermo-refractive (PTR) glass have been successfully used as ultrashort pulse stretchers and compressors in a variety of solid-state and fiber chirped pulse amplification (CPA) laser systems. Compared to traditional pairs of surface gratings, CBG-based stretchers and compressors offer significant advantage in compactness and robustness. They are insensitive to polarization, require virtually no alignment and can handle high average and peak power. At the current technology stage PTR-glass CBGs can provide up to 30 nm spectral bandwidth and up to 300 ps stretched pulse duration. In this paper we propose a concept of sectional CBGs, where multiple CBGs with different central wavelengths recorded in separate PTR-glass wafers are stacked and phased to form a single grating with effective thickness and bandwidth larger than each section. We present results of initial experiment in which pulses from a femtosecond oscillator centered at 1028 nm are stretched by a 32-mm thick CBG to about 160 ps and recompressed by a monolithic 32-mm CBG with 11 nm bandwidth and by a sectional CBG with two 16-mm thick sections each having ~ 5 nm bandwidth and offset central wavelengths: 1025.5 and 1031 nm. In both cases, compressed pulse duration of 350-400 fs, ~ 1.1 × transform-limit was obtained. These results allow CBG-based pulse stretchers and compressors with high stretch ratio and wide bandwidth to be constructed from multiple sections.

  2. Gravitational waveforms with controlled accuracy

    E-print Network

    Roberto Gomez

    2001-06-07

    A partially first-order form of the characteristic formulation is introduced to control the accuracy in the computation of gravitational waveforms produced by highly distorted single black hole spacetimes. Our approach is to reduce the system of equations to first-order differential form on the angular derivatives, while retaining the proven radial and time integration schemes of the standard characteristic formulation. This results in significantly improved accuracy over the standard mixed-order approach in the extremely nonlinear post-merger regime of binary black hole collisions.

  3. Enhancement of sound by soft reflections in exponentially chirped crystals

    NASA Astrophysics Data System (ADS)

    Cebrecos, A.; Picó, R.; Sánchez-Morcillo, V. J.; Staliunas, K.; Romero-García, V.; Garcia-Raffi, L. M.

    2014-12-01

    The enhancement of sound inside a two dimensional exponentially chirped crystal during the soft reflections of waves is experimentally and theoretically explored in this work. The control of this enhancement is achieved by a gradual variation of the dispersion in the system by means of a chirp of the lattice constant. The sound enhancement is produced at some planes of the crystal in which the wave is softly reflected due to a progressive slowing down of the sound wave. We find that the character of the sound enhancement depends on the function of the variation of dispersion, i.e., on the function of the chirp. A simple coupled mode theory is proposed to find the analytical solutions of the sound wave enhancement in the exponentially chirped crystal. Harmonic and time domain numerical simulations are performed to interpret the concept of the soft reflections, and to check the analytically calculated field distributions both in good agreement with experiments. Specially we obtain stronger sound enhancement than in linearly chirped crystals. This sound enhancement could motivate applications in energy harvesting, e.g., to increase the efficiency of detectors and absorbers.

  4. A wireless spread-spectrum communication system using SAW chirped delay lines

    Microsoft Academic Search

    Andreas Springer; Wolfgang Gugler; Mario Huemer; Rainer Koller; Robert Weigel

    2001-01-01

    We report on the use of broad-band chirp signals for spread-spectrum communications in indoor and industrial environments. The well-known pulse compression technique associated with chirp signals is exploited to achieve a highly robust communication system. For the generation and compression of the chirp signals, surface acoustic wave delay lines fabricated from an LiTaO3-X112rotY substrate are used. Center frequency, bandwidth, chirp

  5. A robust ultra-broad-band wireless communication system using SAW chirped delay lines

    Microsoft Academic Search

    Andreas Springer; Mario Huemer; Leonhard Reindl; Clemens C. W. Ruppel; Alfred Pohl; Franz Seifert; Wolfgang Gugler; Robert Weigel

    1998-01-01

    Design and performance of a low-cost wireless communication system for indoor and industrial environments are presented. The system is based on chirp-signal transmission to achieve a robust communication link. For the chirp expansion and compression, surface acoustic wave chirped delay lines fabricated from LiTaO3-X112rotY are used. Center frequency, bandwidth, and chirp rate are 348.8 MHz, 80 MHz, and ±40 MHz\\/?s,

  6. Analysis of Q burst waveforms

    NASA Astrophysics Data System (ADS)

    Ogawa, Toshio; Komatsu, Masayuki

    2007-04-01

    The electric field changes in ELF to VLF were observed with a ball antenna in fair weather at Kochi (latitude 33.3°N, longitude 133.4°E) during 2003-2004. Some 376 Q bursts were obtained, seven examples of which are analyzed in the present study. The continuous frequency spectra of the Q bursts and the background noises from 1.0 Hz to 11 kHz are compared, and it was found that the Q bursts prevail over the background in the frequency range from 1 to 300 Hz. The surplus is 20 dB (in amplitude) near the fundamental mode frequency. The "W"-type changes found in the initial portion of the Q burst waveforms are interpreted as the combined electromagnetic waveform of direct and antipodal waves from the causative lightning strokes. From the time intervals between the two waves, the source-receiver distances are estimated as far as 19 Mm. The pulses to excite the Schumann resonances in the Q bursts are clearly identified.

  7. Experimental investigation of chirp properties induced by signal amplification in quantum-dot semiconductor optical amplifiers.

    PubMed

    Matsuura, Motoharu; Ohta, Hiroaki; Seki, Ryota

    2015-03-15

    We experimentally show the dynamic frequency chirp properties induced by signal amplification in a quantum-dot semiconductor optical amplifier (QD-SOA) for the first time. We also compare the red and blue chirp peak values and temporal chirp changes while changing the gain and injected signal powers of the QD-SOA with those of a common SOA. PMID:25768145

  8. Goldstone Solar System Radar Waveform Generator

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Nguyen, Huy

    2012-01-01

    Due to distances and relative motions among the transmitter, target object, and receiver, the time-base between any transmitted and received signal will undergo distortion. Pre-distortion of the transmitted signal to compensate for this time-base distortion allows reception of an undistorted signal. In most radar applications, an arbitrary waveform generator (AWG) would be used to store the pre-calculated waveform and then play back this waveform during transmission. The Goldstone Solar System Radar (GSSR), however, has transmission durations that exceed the available memory storage of such a device. A waveform generator capable of real-time pre-distortion of a radar waveform to a given time-base distortion function is needed. To pre-distort the transmitted signal, both the baseband radar waveform and the RF carrier must be modified. In the GSSR, this occurs at the up-conversion mixing stage to an intermediate frequency (IF). A programmable oscillator (PO) is used to generate the IF along with a time-varying phase component that matches the time-base distortion of the RF carrier. This serves as the IF input to the waveform generator where it is mixed with a baseband radar waveform whose time-base has been distorted to match the given time-base distortion function producing the modulated IF output. An error control feedback loop is used to precisely control the time-base distortion of the baseband waveform, allowing its real-time generation. The waveform generator produces IF modulated radar waveforms whose time-base has been pre-distorted to match a given arbitrary function. The following waveforms are supported: continuous wave (CW), frequency hopped (FH), binary phase code (BPC), and linear frequency modulation (LFM). The waveform generator takes as input an IF with a time varying phase component that matches the time-base distortion of the carrier. The waveform generator supports interconnection with deep-space network (DSN) timing and frequency standards, and is controlled through a 1 Gb/s Ethernet UDP/IP interface. This real-time generation of a timebase distorted radar waveform for continuous transmission in a planetary radar is a unique capability.

  9. Chirped pulse inverse free-electron laser vacuum accelerator

    DOEpatents

    Hartemann, Frederic V. (Dublin, CA); Baldis, Hector A. (Pleasanton, CA); Landahl, Eric C. (Walnut Creek, CA)

    2002-01-01

    A chirped pulse inverse free-electron laser (IFEL) vacuum accelerator for high gradient laser acceleration in vacuum. By the use of an ultrashort (femtosecond), ultrahigh intensity chirped laser pulse both the IFEL interaction bandwidth and accelerating gradient are increased, thus yielding large gains in a compact system. In addition, the IFEL resonance condition can be maintained throughout the interaction region by using a chirped drive laser wave. In addition, diffraction can be alleviated by taking advantage of the laser optical bandwidth with negative dispersion focusing optics to produce a chromatic line focus. The combination of these features results in a compact, efficient vacuum laser accelerator which finds many applications including high energy physics, compact table-top laser accelerator for medical imaging and therapy, material science, and basic physics.

  10. Broadband-rejection filters using chirped and tilted fiber gratings

    NASA Astrophysics Data System (ADS)

    Liu, Fu; Guo, Tuan; Guan, Bai-Ou

    2014-11-01

    Broadband-trimming band-rejection filters based on chirped and tilted fiber Bragg gratings (CTFBG) are proposed and experimentally demonstrated. The flexible chirp-rate and wide tilt-angle provide the gratings with broadband filtering functions over a large range of bandwidth (from 10 nm to 150 nm), together with a low transmission loss (less than 1 dB) and a negligible back-reflection (lower than 20 dB). The slope profile of CTFBG in transmission can be easily tailored by adjusting the tilt angle, grating irradiation time and chirp rate-grating factor, and it is insensitive to polarization of launch condition. Furthermore, by coating the CTFBG with a suitable polymer (whose refractive index is close to that of the cladding glass), the cladding modes no longer form weakly discrete resonances and leave a smoothly varying attenuation spectrum for high-quality band rejection filters, edge filters and gain equalizers.

  11. Beam energy chirp effects in seeded free-electron lasers

    NASA Astrophysics Data System (ADS)

    Wang, Guanglei; Feng, Chao; Deng, Haixiao; Zhang, Tong; Wang, Dong

    2014-07-01

    Seeded free-electron lasers (FELs) hold great promise for generating high brilliance radiation pulses with a narrow bandwidth, which typically requires an electron bunch with relatively uniform energy distribution. However, it has been pointed out that the beam energy curvature generated in the acceleration process may degrade the output radiation pulse quality of seeded FELs. In this paper, we studied the beam energy chirp effects in various seeded FEL configurations. The theoretical and simulation results show that the performance degradation of high gain harmonic generation scheme is proportional to the beam energy chirp, while the advanced seeding schemes, e.g. echo-enabled harmonic generation and phase merging enhanced harmonic generation, are capable of eliminating the effect of the electron beam energy chirp.

  12. A portable CW/FM-CW Doppler radar for local investigation of severe storms

    SciTech Connect

    Unruh, W.P.; Wolf, M.A.; Bluestein, H.B.

    1988-01-01

    During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm. 2 refs., 2 figs.

  13. Multiple mechanisms shape FM sweep rate selectivity: complementary or redundant?

    PubMed Central

    Williams, Anthony J.; Fuzessery, Zoltan M.

    2012-01-01

    Auditory neurons in the inferior colliculus (IC) of the pallid bat have highly rate selective responses to downward frequency modulated (FM) sweeps attributable to the spectrotemporal pattern of their echolocation call (a brief FM pulse). Several mechanisms are known to shape FM rate selectivity within the pallid bat IC. Here we explore how two mechanisms, stimulus duration and high-frequency inhibition (HFI), can interact to shape FM rate selectivity within the same neuron. Results from extracellular recordings indicated that a derived duration-rate function (based on tonal response) was highly predictive of the shape of the FM rate response. Longpass duration selectivity for tones was predictive of slowpass rate selectivity for FM sweeps, both of which required long stimulus durations and remained intact following iontophoretic blockade of inhibitory input. Bandpass duration selectivity for tones, sensitive to only a narrow range of tone durations, was predictive of bandpass rate selectivity for FM sweeps. Conversion of the tone duration response from bandpass to longpass after blocking inhibition was coincident with a change in FM rate selectivity from bandpass to slowpass indicating an active inhibitory component to the formation of bandpass selectivity. Independent of the effect of duration tuning on FM rate selectivity, the presence of HFI acted as a fastpass FM rate filter by suppressing slow FM sweep rates. In cases where both mechanisms were present, both had to be eliminated, by removing inhibition, before bandpass FM rate selectivity was affected. It is unknown why the auditory system utilizes multiple mechanisms capable of shaping identical forms of FM rate selectivity though it may represent distinct but convergent modes of neural signaling directed at shaping response selectivity for important biologically relevant sounds. PMID:22912604

  14. C1, FM 3-22.27 (FM 23.27) Headquarters

    E-print Network

    US Army Corps of Engineers

    2006 MK 19, 40-mm GRENADE MACHINE GUN, MOD 3 1. Change FM 3-22.27, 28 November 2003 as follows: Remove HEADQUARTERS NO. 3-22.27 DEPARTMENTS OF THE ARMY WASHINGTON, DC, 14 September 2006 MK 19, 40-mm GRENADE MACHINE and Cleaning................................................................... 2-22 2-8. Operation Under

  15. Instrumental waveform distortion on ocean bottom seismometers

    Microsoft Academic Search

    Brian T. R. Lewis; Jonathan D. Tuthill

    1981-01-01

    Data from the 1978 Lopez Island OBS Intercomparison Experiment and deep sea data from University of Washington OBSs show that there is a considerable amount of waveform distortion resulting from the conversion of horizontal motion into vertical motion, here called cross-coupling distortion. This distortion, which substancially reduces the significance of waveform matching with synthetic seismograms, appears to result from rotation

  16. Principal component analysis of lifting waveforms

    Microsoft Academic Search

    Allan T. Wrigley; Wayne J. Albert; Kevin J. Deluzio; Joan M. Stevenson

    2006-01-01

    Background. One limiting factor in lifting research design has been the inability to effectively analyze waveform data, especially when differences in body mass, height, and load magnitude influence the derived kinetic variables. The purpose of this study was to demon- strate the sensitivity of principal component analysis to quantify clinically relevant differences in kinetic lifting waveforms over three load magnitudes

  17. Optimal adaptive waveform selection for target tracking

    Microsoft Academic Search

    B. L. Scala; M. Rezaeian; B. Moran

    2005-01-01

    Modern phased array radars, with flexible waveform generation and beam steering capability, are able to adaptively modify their performance to suit a variety of environments. This power has not yet been fully exploited, in part because of the lack of suitable scheduling algorithms. This paper describes an optimal adaptive waveform selection algorithm for target tracking. An adaptive scheduling algorithm that

  18. Dense Monoenergetic Proton Beams from Chirped Laser-Plasma Interaction

    NASA Astrophysics Data System (ADS)

    Galow, Benjamin J.; Salamin, Yousef I.; Liseykina, Tatyana V.; Harman, Zoltán; Keitel, Christoph H.

    2011-10-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultraintense (107 particles per bunch) and phase-space collimated beams of protons (energy spread of about 1%) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 1021W/cm2.

  19. Non-diffracting chirped Bessel waves in optical antiguides

    E-print Network

    Chremmos, Ioannis

    2015-01-01

    Chirped Bessel waves are introduced as stable (non-diffracting) solutions of the paraxial wave equation in optical antiguides with a power-law radial variation in their index of refraction. Through numerical simulations, we investigate the propagation of apodized (finite-energy) versions of such waves, with or without vorticity, in antiguides with practical parameters. The new waves exhibit a remarkable resistance against the defocusing effect of the unstable index potentials, outperforming standard Gaussians with the same full width at half maximum. The chirped profile persists even under conditions of eccentric launching or antiguide bending and is also capable of self-healing like standard diffraction-free beams in free space.

  20. Spectral windowing with chirped magneto-optical Bragg gratings

    NASA Astrophysics Data System (ADS)

    Jonsson, Fredrik; Flytzanis, Christos

    2005-01-01

    We present a theory on a novel class of magneto-optical devices operated by means of magneto-optically induced refractive-index perturbations in chirped Bragg gratings. The predicted effect of the introduced perturbation is an opening of a narrow transmission window in the band-blocking transmission of the chirped grating. The narrow transmission window is tunable in wavelength, and relative transmission and the effects of multiple, spatially separated perturbations can also be superimposed, hence allowing for tunable, magneto-optically operated, multichannel add-drop multiplexors suitable for modularization in integrated optics.

  1. Chirped pulse excitation of two-atom Rydberg states

    E-print Network

    Kuznetsova, Elena

    2015-01-01

    We analyze excitation of two ground state atoms to a double Rydberg state by a two-photon chirped optical pulse in the regime of adiabatic rapid passage. For intermediate Rydberg-Rydberg interaction strengths, relevant for atoms separated by $\\sim$ten $\\mu$m, adiabatic excitation can be achieved at experimentally feasible Rabi frequencies and chirp rates of the pulses, resulting in high transfer efficiencies. We also study the adiabatic transfer between ground and Rydberg states as a means to realize a controlled phase gate between atomic qubits.

  2. Analysis in the instantaneous frequency forms of a chirped laser pulse

    SciTech Connect

    Yuan, C. J.; Wu, X. Y.; Wang, P. X. [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education, China and Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433 (China); Wang, J. X. [State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062 (China)

    2011-10-15

    We analyze two forms of the instantaneous frequency of a linearly chirped laser pulse. Using a 3D test particle simulation, numerical results are presented for electrons accelerated by a chirped laser pulse with these two linearly chirped forms of the instantaneous frequency. We summarize that the linearly chirped frequency, {omega}(t)={omega}{sub 0}[1-{alpha}(t-z/c)] is reasonable, {omega}{sub 0} is laser frequency at z=0 and t=0, and {alpha} is the frequency chirp parameter.

  3. Injection and acceleration of electron bunch in a plasma wakefield produced by a chirped laser pulse

    SciTech Connect

    Afhami, Saeedeh; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir [Department of Physics, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114 (Iran, Islamic Republic of)

    2014-06-15

    An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.

  4. Quantum cascade laser FM spectroscopy of explosives

    NASA Astrophysics Data System (ADS)

    Gutmann, Zach; Clasp, Trocia; Lue, Chris; Johnson, Tiffani; Ingle, Taylor; Jamison, Janet; Buchanan, Roger; Reeve, Scott

    2013-05-01

    Polyisobutylene is an industrial polymer that is widely used in a number of applications including the manufacture of military grade explosives. We have examined the vapor emanating from a series of different molecular weight samples of polyisobutylene using high resolution Quantum Cascade Laser FM spectroscopy. The vapor phase spectra all exhibit a rovibrational structure similar to that for the gas phase isobutylene molecule. We have assigned the structure in the 890 cm-1 and 1380 cm-1 regions to the isobutylene ?28 and ?7 fundamental bands respectively. These spectroscopic signatures may prove useful for infrared sensing applications. Here we will present the infrared signatures along with recent GCMS data from a sample of C4, utilizing solid-phase microextraction vapor collection fibers, which confirm the presence of isobutylene as one of the volatile bouquet species in RDX-based explosives.

  5. What FM can offer DFCS design

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1990-01-01

    The results of aircrafts and spacecrafts flight tests are reported. It is shown that the problems of Digital Flight Control Systems (DFCS) are the problems of systems whose complexity has exceeded the reach of the intellectual tools employed. It is also shown that intuition, experience, and techniques derived from mechanical and analog systems are insufficient for complex, integrated, digital systems. Formal Methods (FM) of computer science can offer DFCS systematic techniques for the construction of trustworthy software, including: techniques for the precise specification of requirements and the development of designs; systematic approaches to the design and structuring of distributed and concurrent systems; fault tolerance algorithms; and systematic methods of testing and analytic methods of verification.

  6. Superfluid dynamics of 258Fm fission

    E-print Network

    Scamps, Guillaume; Lacroix, Denis

    2015-01-01

    Theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The slow, mostly adiabatic motion through the fission barrier is followed by a fast, non-adiabatic descent of the potential between the fragments. The latter stage is essentially unexplored. However, it is crucial as it generates most of the excitation energy in the fragments. The superfluid dynamics in the latter stage of fission is obtained with the time-dependent Hartree-Fock theory including BCS dynamical pairing correlations. The fission modes of the 258Fm nucleus are studied. The resulting fission fragment characteristics show a good agreement with experimental data. Quantum shell effects are shown to play a crucial role in the dynamics and formation of the fragments. The importance of quantum fluctuations beyond the independent particle/quasi-particle picture is underlined and qualitatively studied.

  7. Superfluid dynamics of 258Fm fission

    E-print Network

    Guillaume Scamps; Cédric Simenel; Denis Lacroix

    2015-01-15

    Theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The slow, mostly adiabatic motion through the fission barrier is followed by a fast, non-adiabatic descent of the potential between the fragments. The latter stage is essentially unexplored. However, it is crucial as it generates most of the excitation energy in the fragments. The superfluid dynamics in the latter stage of fission is obtained with the time-dependent Hartree-Fock theory including BCS dynamical pairing correlations. The fission modes of the 258Fm nucleus are studied. The resulting fission fragment characteristics show a good agreement with experimental data. Quantum shell effects are shown to play a crucial role in the dynamics and formation of the fragments. The importance of quantum fluctuations beyond the independent particle/quasi-particle picture is underlined and qualitatively studied.

  8. High-energy half-cycle cutoffs in high harmonic and rescattered electron spectra using waveform-controlled few-cycle infrared pulses

    NASA Astrophysics Data System (ADS)

    Geiseler, H.; Ishii, N.; Kaneshima, K.; Kitano, K.; Kanai, T.; Itatani, J.

    2014-10-01

    We developed a few-cycle waveform-controlled light source for infrared pulses at 1.6 ? m that is based on optical chirped-pulse amplification in Bi{{B}3}{{O}6} (BIBO) crystals pumped by Ti:sapphire lasers. Using this source, we observe soft x-ray high harmonics that extend up to a photon energy of ? 320 eV, as well as high-energy photoelectrons up to ? 1 keV. The spectra of the high harmonics and photoelectrons have clear signatures of half-cycle cutoffs that can be used to extract electronic and molecular dynamics on an attosecond time scale.

  9. Electron heating enhancement by frequency-chirped laser pulses

    SciTech Connect

    Yazdani, E.; Afarideh, H., E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Sadighi-Bonabi, R., E-mail: Sadighi@sharif.ir [Department of Physics, Sharif University of Technology, P.O. Box 11365-9567, Tehran (Iran, Islamic Republic of); Riazi, Z. [Physics and Accelerator School, Tehran (Iran, Islamic Republic of); Hora, H. [Department of Theoretical Physics, University of New South Wales, Sydney 2052 (Australia)

    2014-09-14

    Propagation of a chirped laser pulse with a circular polarization through an uprising plasma density profile is studied by using 1D-3V particle-in-cell simulation. The laser penetration depth is increased in an overdense plasma compared to an unchirped pulse. The induced transparency due to the laser frequency chirp results in an enhanced heating of hot electrons as well as increased maximum longitudinal electrostatic field at the back side of the solid target, which is very essential in target normal sheath acceleration regime of proton acceleration. For an applied chirp parameter between 0.008 and 0.01, the maximum amount of the electrostatic field is improved by a factor of 2. Furthermore, it is noticed that for a chirped laser pulse with a{sub 0}?=?5, because of increasing the plasma transparency length, the laser pulse can penetrate up to about n{sub e}???6n{sub c}, where n{sub c} is plasma critical density. It shows 63% increase in the effective critical density compared to the relativistic induced transparency regime for an unchirped condition.

  10. Few-cycle chirped-pulse parametric amplification

    Microsoft Academic Search

    A. Baltuska; N. Ishii; T. Fuji; X. Gu; N. Forget; D. Kaplan; A. Galvanauskas; F. Krausz

    2006-01-01

    We review progress in the development of kilohertz-repetition-rate few-cycle optical parametric chirped pulse amplifiers (OPCPA) in the near-IR (700-1000 nm) and IR (1700-2800 nm) spectral ranges. These sources hold promise for applications in extreme nonlinear optics and attosecond physics.

  11. Pulse compression on the Mark III FEL using energy chirping

    Microsoft Academic Search

    Eric B. Szarmes; Stephen V. Benson; John M. J. Madey

    1990-01-01

    We have performed preliminary simulations of the optical-pulse formation in the Mark III FEL using electron micropulses which exhibit a linear energy dependence on time, and have demonstrated optical pulses whose frequency chirps agree fairly well with those obtained analytically by assuming that the resonance condition determines the lasing wavelength during the pulse. In a typical case, we project pulse

  12. Chirped frequency transfer: a tool for synchronization and time transfer.

    PubMed

    Raupach, Sebastian M F; Grosche, Gesine

    2014-06-01

    We propose and demonstrate the phase-stabilized transfer of a chirped frequency as a tool for synchronization and time transfer. Technically, this is done by evaluating remote measurements of the transferred, chirped frequency. The gates of the frequency counters, here driven by a 10-MHz oscillation derived from a hydrogen maser, play a role analogous to the 1-pulse per second (PPS) signals usually employed for time transfer. In general, for time transfer, the gates consequently must be related to the external clock. Synchronizing observations based on frequency measurements, on the other hand, only requires a stable oscillator driving the frequency counters. In a proof of principle, we demonstrate the suppression of symmetrical delays, such as the geometrical path delay. We transfer an optical frequency chirped by around 240 kHz/s over a fiber link of around 149 km. We observe an accuracy and simultaneity, as well as a precision (Allan deviation, 18,000 s averaging interval) of the transferred frequency of around 2 × 10(-19). We apply chirped frequency transfer to remote measurements of the synchronization between two counters' gate intervals. Here, we find a precision of around 200 ps at an estimated overall uncertainty of around 500 ps. The measurement results agree with those obtained from reference measurements, being well within the uncertainty. In the present setup, timing offsets up to 4 min can be measured unambiguously. We indicate how this range can be extended further. PMID:24859656

  13. Detection algorithm of big bandwidth chirp signals based on STFT

    NASA Astrophysics Data System (ADS)

    Wang, Jinzhen; Wu, Juhong; Su, Shaoying; Chen, Zengping

    2014-10-01

    Aiming at solving the problem of detecting the wideband chirp signals under low Signal-to-Noise Ratio (SNR) condition, an effective signal detection algorithm based on Short-Time-Fourier-Transform (STFT) is proposed. Considering the characteristic of dispersion of noise spectrum and concentration of chirp spectrum, STFT is performed on chirp signals with Gauss window by fixed step, and these frequencies of peak spectrum obtained from every STFT are in correspondence to the time of every stepped window. Then, the frequencies are binarized and the approach similar to mnk method in time domain is used to detect the chirp pulse signal and determine the coarse starting time and ending time. Finally, the data segments, where the former starting time and ending time locate, are subdivided into many segments evenly, on which the STFT is implemented respectively. By that, the precise starting and ending time are attained. Simulations shows that when the SNR is higher than -28dB, the detection probability is not less than 99% and false alarm probability is zero, and also good estimation accuracy of starting and ending time is acquired. The algorithm is easy to realize and surpasses FFT in computation when the width of STFT window and step length are selected properly, so the presented algorithm has good engineering value.

  14. Constrained bandwidth waveforms with minimal dilation sensitivity

    NASA Astrophysics Data System (ADS)

    Ricker, Dennis W.

    1993-07-01

    The sensitivity of a waveform to velocity-induced time dilation is an important consideration when performing replica correlation for coherent echo location or communication. Bandpass waveforms which have envelopes which are insensitive to this effect may be efficiently processed by what are known as narrowband receivers in which envelope dilation is fixed and Doppler tested using simple spectrum analysis (fast Fourier transform (FFT)) processing. The peak level of the waveform ambiguity function (AF) is a measure of signal coherence and may be used to gauge the distortion of the waveform induced by the dilation effect. The degree of AF attenuation is shown to be proportional to the dilation parameter or velocity, waveform traveling wave (TW) product, and a sensitivity parameter which depends upon the envelope function utilized. Classes of symmetric, constrained bandwidth, phase modulated envelope functions are derived which are minimally dilation sensitive (Doppler tolerant). When the resulting waveforms are used with a simple correlation receiver structure and the echo data is derived from slowly fluctuating point scattering in white Gaussian noise, the receiver becomes an uncoupled joint estimator of delay and dilation (Doppler). In the case of the bandpass waveforms, it is shown that only odd symmetry of the phase modulation yields an uncoupled estimator. The envelopes may use various slowly varying even amplitude window functions affording a measure of freedom in the design of specific ambiguity properties.

  15. 47 CFR 73.3573 - Processing FM broadcast station applications.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...community of license of an FM station. (4) Non-reserved band...Rules permitting short spaced stations as set forth in § 73.215 as...exhibit must include a site map or, in the alternative...noncommercial educational FM stations, applications for such...

  16. HowardFM.Theroleoflaparoscopyintheevaluationofchronic pelvicpain:pitfallswithanegativelaparoscopy.JAmAssoc

    E-print Network

    Goldman, Steven A.

    GynecologicSurgery2000;5:3-12. · HowardFM.ChronicPelvicPaininWomen.AmerJManaged Care2001;7:1001-13. · HowardFM.GynecologicPain.In:HandbookofPain,twisting,pinsandneedles,numbness,andhypersensitivity. Thepainispiercingandverycomparabletoatoothache.Itoften startsinoneplaceandprogresses.Frequentlythereisalsourinary, anal pudendal neuralgia what should they do to get help? First

  17. Preparing Students to Take SOA/CAS Exam FM/2

    ERIC Educational Resources Information Center

    Marchand, Richard J.

    2014-01-01

    This paper provides suggestions for preparing students to take the actuarial examination on financial mathematics, SOA/CAS Exam FM/2. It is based on current practices employed at Slippery Rock University, a small public liberal arts university. Detailed descriptions of our Theory of Interest course and subsequent Exam FM/2 prep course are provided…

  18. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  19. Design of a 12 Channel FM Microwave Receiver.

    ERIC Educational Resources Information Center

    Risch, Craig O.; And Others

    The design, fabrication, and performance of elements of a low cost FM microwave satellite ground station receiver are described. It is capable of accepting 12 contiguous color television equivalent bandwidth channels in the 11.72 to 12.2 GHz band. Each channel is 40 MHz wide and incorporates a 4MHz guard band. The modulation format is wideband FM,…

  20. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  1. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  2. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  3. 47 CFR 73.4108 - FM transmitter site map submissions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false FM transmitter site map submissions. 73.4108 Section 73.4108 Telecommunication...to All Broadcast Stations § 73.4108 FM transmitter site map submissions. See Memorandum Opinion and Order and...

  4. FM-CW radar sensing of the lower atmosphere

    Microsoft Academic Search

    V. R. Noonkester; J. H. Richter

    1980-01-01

    FM-CW radars have revealed many unique marine boundary layer echoes in great detail and permit new interpretations when they are operated simultaneously with other remote sensors. Three different subject areas and associated observations are presented. First, an FM-CW radar can provide information on tropospheric radio propagation conditions through a refractive index profile updating procedure. Mesoscale variations in radio propagation conditions

  5. Radiation pattern shaping for FM broadcast-optimizing coverage

    Microsoft Academic Search

    Gerino P. Mappatao

    2010-01-01

    This paper describes how to configure the radiation pattern of an omnidirectional FM antenna to at least approximate a desired directional radiation pattern. The desired radiation pattern is based on the population location within the coverage area of an FM radio station. In this way, the station will transmit signal only in directions where the signal is needed, thereby the

  6. LISA Parameter Estimation using Numerical Merger Waveforms

    NASA Technical Reports Server (NTRS)

    Thorpe, J. I.; McWilliams, S.; Baker, J.

    2008-01-01

    Coalescing supermassive black holes are expected to provide the strongest sources for gravitational radiation detected by LISA. Recent advances in numerical relativity provide a detailed description of the waveforms of such signals. We present a preliminary study of LISA's sensitivity to waveform parameters using a hybrid numerical/analytic waveform describing the coalescence of two equal-mass, nonspinning black holes. The Synthetic LISA software package is used to simulate the instrument response and the Fisher information matrix method is used to estimate errors in the waveform parameters. Initial results indicate that inclusion of the merger signal can significantly improve the precision of some parameter estimates. For example, the median parameter errors for an ensemble of systems with total redshifted mass of 10(exp 6) deg M solar mass at a redshift of z is approximately 1 were found to decrease by a factor of slightly more than two when the merger was included.

  7. Delay modeling using ramp and realistic signal waveforms

    Microsoft Academic Search

    Rupal Gandhi; Jim Shiffer; Dhrumil Gandhi; Dimitrios Velenis

    2005-01-01

    Accurate estimation of circuit delay has become a primary requirement to ensure the correct synchronization of high speed synchronous integrated circuits. In this paper, the difference in circuit delay simulated using ramp and realistic signal waveforms is investigated. It is shown that the realistic signal waveform produces larger delay estimates than the ramp waveform. Ramp and realistic waveforms are also

  8. High-Voltage, Asymmetric-Waveform Generator

    NASA Technical Reports Server (NTRS)

    Beegle, Luther W.; Duong, Tuan A.; Duong, Vu A.; Kanik, Isik

    2008-01-01

    The shapes of waveforms generated by commercially available analytical separation devices, such as some types of mass spectrometers and differential mobility spectrometers are, in general, inadequate and result in resolution degradation in output spectra. A waveform generator was designed that would be able to circumvent these shortcomings. It is capable of generating an asymmetric waveform, having a peak amplitude as large as 2 kV and frequency of several megahertz, which can be applied to a capacitive load. In the original intended application, the capacitive load would consist of the drift plates in a differential-mobility spectrometer. The main advantage to be gained by developing the proposed generator is that the shape of the waveform is made nearly optimum for various analytical devices requiring asymmetric-waveform such as differential-mobility spectrometers. In addition, this waveform generator could easily be adjusted to modify the waveform in accordance with changed operational requirements for differential-mobility spectrometers. The capacitive nature of the load is an important consideration in the design of the proposed waveform generator. For example, the design provision for shaping the output waveform is based partly on the principle that (1) the potential (V) on a capacitor is given by V=q/C, where C is the capacitance and q is the charge stored in the capacitor; and, hence (2) the rate of increase or decrease of the potential is similarly proportional to the charging or discharging current. The proposed waveform generator would comprise four functional blocks: a sine-wave generator, a buffer, a voltage shifter, and a high-voltage switch (see Figure 1). The sine-wave generator would include a pair of operational amplifiers in a feedback configuration, the parameters of which would be chosen to obtain a sinusoidal timing signal of the desired frequency. The buffer would introduce a slight delay (approximately equal to 20 ns) but would otherwise leave the fundamental timing signal unchanged. The buffered timing signal would be fed as input to the level shifter. The output of the level shifter would serve as a timing and control signal for the high-voltage switch, causing the switch to alternately be (1) opened, allowing the capacitive load to be charged from a high-voltage DC power supply; then (2) closed to discharge the capacitive load to ground. Hence, the output waveform would closely approximate a series of exponential charging and discharging curves (see Figure 2).

  9. GRC GSFC TDRSS Waveform Metrics Report

    NASA Technical Reports Server (NTRS)

    Mortensen, Dale J.

    2013-01-01

    The report presents software metrics and porting metrics for the GGT Waveform. The porting was from a ground-based COTS SDR, the SDR-3000, to the CoNNeCT JPL SDR. The report does not address any of the Operating Environment (OE) software development, nor the original TDRSS waveform development at GSFC for the COTS SDR. With regard to STRS, the report presents compliance data and lessons learned.

  10. Group features of small seismic waveforms

    E-print Network

    Wenlong Liu; Yucheng Liu

    Abstract: This paper demonstrates several group features observed from small seismic waveforms and distinguishes abnormal group features that preceded destructive major shocks from normal ones. Important group features discussed in this paper include direction of seismic wave’s first motion, amplitude ratio, half period of the first motion, frequency components of earthquakes, and linearity of seismic waveform. The group features illustrated in this paper have been used as important criteria in earthquake prediction.

  11. Video compression transmission via FM radio

    NASA Astrophysics Data System (ADS)

    Do, Chat C.; Szu, Harold H.

    2001-03-01

    At this moment of technology, video still represents the most effective communication in the world. In recent study from Dr. Charles Hsu and Dr. Harold Szu, the video can be compressed highly using feature-preserving but lossy discrete wavelet transform (DWT) technology. The processes of DWT technology are to improve the video compression level, storage capacity, filtering, and restoration techniques. This technology would allow running real time video through radio with fairly quality performance due to their compression and computational complexity techniques. After the compression, the video can be stored and transmitted at 16kbps through any reliable media and still retain a reasonable video quality. Hsu and Szu have done serious simulations and successfully implemented in the brassboards. The main objective of this paper is to present how to transmit this highly compressed video to the users via FM radio link interactively by using special technique. This application can enable many radio users receive video through their radio receiver box. This application has more interested in developing countries where television transmission is hardly afforded for education, distance learning, telemedicine, low cost sports, one-way videoconference and entertainment broadcasting.

  12. Design, fabrication and characterization of a specially apodized chirped grating for reciprocal second harmonic generation.

    PubMed

    Bostani, Ameneh; Ahlawat, Meenu; Tehranchi, Amirhossein; Morandotti, Roberto; Kashyap, Raman

    2015-02-23

    A specially-designed apodized chirped PPLN based on particular positioning of poled regions within the periods has been realized theoretically and experimentally to demonstrate the reciprocal response in the SHG spectra over a 30-nm bandwidth, for up-chirp and down-chirp directions. The simulation results are compared with another apodized chirped PPLN for which the placement of poled regions is deviated from optimum positions. The average power difference is less than 0.75 dB and the standard deviations of extrema on second harmonic power responses are 1.34 dB and 1.64 dB for two up-chirp and down-chirp directions respectively. PMID:25836551

  13. Optical chirp z-transform processor with a simplified architecture.

    PubMed

    Ngo, Nam Quoc

    2014-12-29

    Using a simplified chirp z-transform (CZT) algorithm based on the discrete-time convolution method, this paper presents the synthesis of a simplified architecture of a reconfigurable optical chirp z-transform (OCZT) processor based on the silica-based planar lightwave circuit (PLC) technology. In the simplified architecture of the reconfigurable OCZT, the required number of optical components is small and there are no waveguide crossings which make fabrication easy. The design of a novel type of optical discrete Fourier transform (ODFT) processor as a special case of the synthesized OCZT is then presented to demonstrate its effectiveness. The designed ODFT can be potentially used as an optical demultiplexer at the receiver of an optical fiber orthogonal frequency division multiplexing (OFDM) transmission system. PMID:25607197

  14. Pulse compression on the Mark III FEL using energy chirping

    NASA Astrophysics Data System (ADS)

    Szarmes, Eric B.; Benson, Stephen V.; Madey, John M. J.

    1990-10-01

    We have performed preliminary simulations of the optical-pulse formation in the Mark III FEL using electron micropulses which exhibit a linear energy dependence on time, and have demonstrated optical pulses whose frequency chirps agree fairly well with those obtained analytically by assuming that the resonance condition determines the lasing wavelength during the pulse. In a typical case, we project pulse compression by a factor of 13.3, from an initial pulse width of 3.13 ps to a final pulse width of 236 fs, at a wavelength of 3.35 ?m and an electron energy chirp of +2% (energy increasing towards the back of the pulse). This represents an optical pulse less than half as short as the slippage length of 47 magnet periods for this wavelength.

  15. Chirp Measurements Of A Ten Joule Pulsed CO2 Oscillator

    NASA Astrophysics Data System (ADS)

    Hoag, Ethan D.

    1989-07-01

    Chirp measurements have been conducted on the pulsed output of an unstable resonator oscillating on the P20 line of the 10.6 micron band of an e-beam sustained CO2 gain medium. A heterodyne method was used, mixing the oscillator signal with a cw laser operating on the same line. The mode volume was approximately 5 liters at a pressure between 1/3 and 1/2 atm. The measurements were conducted at pulse lengths of the order of 20 microseconds and are useful in characterizing the device for use in radar applications. Chirp values of less than 1 MHz are observed during the first 10 ? sec, in the remainder of the pulse, values of several MHz are observed, with decreasing frequency.

  16. Chirp Measurements Of A Ten Joule Pulsed CO2 Oscillator

    NASA Astrophysics Data System (ADS)

    Hoag, Ethan D.

    1989-12-01

    Chirp measurements have been conducted on the pulsed output of an unstable resonator oscillating on the P20 line of the 10.6 micron band of an e-beam sustained CO2 gain medium. The mode volume was approximately 5 liters at a pressure between 1/3 and 1/2 atm. The measurements were conducted at pulse lengths of the order of 10 microseconds and are useful in characterizing the device for use in radar applications. A heterodyne technique was used, mixing the oscillator signal with a cw laser operating on the P20 line, but offset approximately 40 MHz in order to resolve uncertainties in the sense of the frequency deviation. Chirp values of less than 400 kHz are observed during the first 10 ?sec.

  17. Dense monoenergetic proton beams from chirped laser-plasma interaction.

    PubMed

    Galow, Benjamin J; Salamin, Yousef I; Liseykina, Tatyana V; Harman, Zoltán; Keitel, Christoph H

    2011-10-28

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultraintense (10(7) particles per bunch) and phase-space collimated beams of protons (energy spread of about 1%) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10(21) W/cm(2). PMID:22107638

  18. A 32x32 pixel focal plane array ladar system using chirped amplitude modulation

    NASA Astrophysics Data System (ADS)

    Stann, Barry L.; Aliberti, Keith; Carothers, Daniel; Dammann, John; Dang, Gerard; Giza, Mark M.; Lawler, William B.; Redman, Brian C.; Simon, Deborah R.

    2004-09-01

    The Army Research Laboratory is researching system architectures and components required to build a 32x32 pixel scannerless ladar breadboard. The 32x32 pixel architecture achieves ranging based on a frequency modulation/continuous wave (FM/cw) technique implemented by directly amplitude modulating a near-IR diode laser transmitter with a radio frequency (RF) subcarrier that is linearly frequency modulated (i.e. chirped amplitude modulation). The backscattered light is focused onto an array of metal-semiconductor-metal (MSM) detectors where it is detected and mixed with a delayed replica of the laser modulation signal that modulates the responsivity of each detector. The output of each detector is an intermediate frequency (IF) signal (a product of the mixing process) whose frequency is proportional to the target range. Pixel read-out is achieved using code division multiple access techniques as opposed to the usual time-multiplexed techniques to attain high effective frame rates. The raw data is captured with analog-to-digital converters and fed into a PC to demux the pixel data, compute the target ranges, and display the imagery. Last year we demonstrated system proof-of-principle for the first time and displayed an image of a scene collected in the lab that was somewhat corrupted by pixel-to-pixel cross-talk. This year we report on system modifications that reduced pixel-to-pixel cross-talk and new hardware and display codes that enable near real-time stereo display of imagery on the ladar's control computer. The results of imaging tests in the laboratory will also be presented.

  19. A robust ultra broadband wireless communication system using SAW chirped delay lines

    Microsoft Academic Search

    A. Springer; A. Pohl; W. Gugler; M. Huemer; L. Reindl; C. C. W. Ruppel; F. Seifert; R. Weigel

    1998-01-01

    Design and performance of SAW chirped delay lines on LiTaO3 -X112rotY for a wireless communication system are presented. Center frequency, bandwidth and chirp rate are 350 MHz, 80 MHz, and ±20 MHz\\/s, respectively. An optimized square-root weighting was chosen to reduce the sidelobes of the compressed pulse to -42 dB compared to the correlation peak. The chirp filters have been

  20. Pulse-shape effects on frequency chirping in single-frequency semiconductor lasers under current modulation

    Microsoft Academic Search

    T. Shen; G. Agrawal

    1986-01-01

    Directly modulated semiconductor lasers exhibit dynamic frequency shifts (chirping) due to gain-induced variations of the refractive index. Using the small-signal analysis of the single-mode rate equations, the effect of current-pulse shape on frequency chirping is analyzed, and the results are compared for the cases of sinusoidal and square-wave modulations. The chirp is generally larger for the square-wave case. However, its

  1. Multimillijoule chirped parametric amplification of few-cycle pulses

    Microsoft Academic Search

    N. Ishii; L. Turi; V. S. Yakovlev; T. Fuji; F. Krausz; A. Baltuska; R. Butkus; G. Veitas; V. Smilgevicius; R. Danielius; A. Piskarskas

    2005-01-01

    The concept of optical parametric chirped-pulse amplification is applied to attain pulses with energies up to 8 mJ and a bandwidth of more than 100 THz. Stretched broadband seed pulses from a Ti:sapphire oscillator are amplified in a multistage noncollinear type I phase-matched beta-barium borate parametric amplifier by use of an independent picosecond laser with lock-to-clock repetition rate synchronization. Partial

  2. Chirped multilayer coatings for increased x-ray throughput

    Microsoft Academic Search

    S. P. Vernon; D. G. Stearns; R. S. Rosen

    1993-01-01

    Chirped Mo--Si multilayer coatings, where the multilayer period is systematically varied throughout the deposition process, exhibit an increased x-ray bandwidth at normal incidence with a corresponding increase in the integrated reflectance of as much as 20% at [lambda][similar to]13 nm. The increased bandwidth is accompanied by a slight reduction in peak reflectance. The relation between the integrated and peak reflectance

  3. Excitation and control of chirped nonlinear ion-acoustic waves

    NASA Astrophysics Data System (ADS)

    Friedland, L.; Shagalov, A. G.

    2014-05-01

    Large-amplitude ion acoustic waves are excited and controlled by a chirped frequency driving perturbation. The process involves capturing into autoresonance (a continuous nonlinear synchronization) with the drive by passage through the linear resonance in the problem. The transition to autoresonance has a sharp threshold on the driving amplitude. The theory of this transition is developed beyond the Korteweg-de Vries limit by using the Whitham's averaged variational principle within the water bag model and compared with Vlasov-Poisson simulations.

  4. Chirping a two-photon transition in a multistate ladder

    SciTech Connect

    Merkel, Wolfgang; Mack, Holger; Schleich, Wolfgang P.; Lutz, Eric; Paulus, Gerhard G.; Girard, Bertrand [Institut fuer Quantenphysik, Universitaet Ulm, Albert-Einstein-Allee 11, D-89081 Ulm (Germany) and Department of Physics, Universitaet Augsburg, D-86135 Augsburg (Germany) and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States) and Laboratoire de Collisions, Agregats et Reactivite - UMR 5589, CNRS-Universite Paul Sabatier Toulouse 3, IRSAMC, Toulouse (France)

    2007-08-15

    We consider a two-photon transition in a specific ladder system driven by a chirped laser pulse. In the weak field limit, we find that the excited state probability amplitude arises due to interference of multiple quantum paths which are weighted by quadratic phase factors. The excited state population has the form of a Gauss sum which plays a prominent role in number theory.

  5. Superharmonic imaging with chirp coded excitation: filtering spectrally overlapped harmonics.

    PubMed

    Harput, Sevan; McLaughlan, James; Cowell, David M J; Freear, Steven

    2014-11-01

    Superharmonic imaging improves the spatial resolution by using the higher order harmonics generated in tissue. The superharmonic component is formed by combining the third, fourth, and fifth harmonics, which have low energy content and therefore poor SNR. This study uses coded excitation to increase the excitation energy. The SNR improvement is achieved on the receiver side by performing pulse compression with harmonic matched filters. The use of coded signals also introduces new filtering capabilities that are not possible with pulsed excitation. This is especially important when using wideband signals. For narrowband signals, the spectral boundaries of the harmonics are clearly separated and thus easy to filter; however, the available imaging bandwidth is underused. Wideband excitation is preferable for harmonic imaging applications to preserve axial resolution, but it generates spectrally overlapping harmonics that are not possible to filter in time and frequency domains. After pulse compression, this overlap increases the range side lobes, which appear as imaging artifacts and reduce the Bmode image quality. In this study, the isolation of higher order harmonics was achieved in another domain by using the fan chirp transform (FChT). To show the effect of excitation bandwidth in superharmonic imaging, measurements were performed by using linear frequency modulated chirp excitation with varying bandwidths of 10% to 50%. Superharmonic imaging was performed on a wire phantom using a wideband chirp excitation. Results were presented with and without applying the FChT filtering technique by comparing the spatial resolution and side lobe levels. Wideband excitation signals achieved a better resolution as expected, however range side lobes as high as -23 dB were observed for the superharmonic component of chirp excitation with 50% fractional bandwidth. The proposed filtering technique achieved >50 dB range side lobe suppression and improved the image quality without affecting the axial resolution. PMID:25389159

  6. Hyper dispersion pulse compressor for chirped pulse amplification systems

    DOEpatents

    Barty, Christopher P. J. (Hayward, CA)

    2011-11-29

    A grating pulse compressor configuration is introduced for increasing the optical dispersion for a given footprint and to make practical the application for chirped pulse amplification (CPA) to quasi-narrow bandwidth materials, such as Nd:YAG. The grating configurations often use cascaded pairs of gratings to increase angular dispersion an order of magnitude or more. Increased angular dispersion allows for decreased grating separation and a smaller compressor footprint.

  7. Progress Towards Chirped-Pulse Fourier Transform Thz Spectroscopy

    NASA Astrophysics Data System (ADS)

    Douglass, Kevin O.; Plusquellic, David F.; Gerecht, Eyal

    2010-06-01

    New opportunities are provided by the development of higher power THz frequency multiplier sources, the development of a broadband Chirped-Pulse FTMW spectroscopy technique at microwave and mm Wave frequencies, and recently demonstrated heterodyne hot electron bolometer detection technology in the THz frequency region with near quantum noise-limited performance and high spectral resolution. Combining these three technologies and extending the chirped-pulse technique to 0.85 THz enables a host of new applications. NIST is currently pursing applications as a point sensor for greenhouse gases, volatile organic compounds, and potentially human breath. The generation and detection of phase stable chirped pulses at 850 GHz will be demonstrated. A description of the experimental setup and preliminary data will be presented for nitrous oxide. G.G. Brown, B.C. Dian, K.O. Douglass, S.M. Geyer, S. Shipman and B.H. Pate, Rev.Sci.Instrum. 79 (2008) 053103. E. Gerecht, D. Gu, L. You, K.S. Yngvesson, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES. 56, (2008) 1083.

  8. An improved processing sequence for uncorrelated Chirp sonar data

    NASA Astrophysics Data System (ADS)

    Baradello, Luca

    2014-12-01

    Chirp sonar systems can be used to obtain high resolution seismic reflection images of the sub-seafloor during marine surveys. The exact knowledge of the Chirp signature allows the use of deterministic algorithms to process the data, similarly to that applied to Vibroseis data on land. Here, it is described an innovative processing sequence to be applied to uncorrelated Chirp data, which can improve vertical and lateral resolution compared to conventional methods. It includes application of a Wiener filter to transform a frequency-modulated sweep into a minimum-phase pulse sequence. In this way, the data become causal and can undergo predictive deconvolution to reduce ringing and enhance vertical resolution. Afterwards, FX-deconvolution and Stolt migration can be applied to obtain an improved imaging of the subsurface. The result of this procedure is a seismic reflection image with higher resolution than traditional ones, which are normally represented using the envelope function of the signal. This technique can be particularly useful for engineering-geotechnical surveys and archaeological investigations that require a fine detail imaging of the uppermost meters of the sub-seafloor.

  9. Kinetic view of chirped optical lattice gas heating

    NASA Astrophysics Data System (ADS)

    Graul, J. S.; Gimelshein, S. F.; Lilly, T. C.

    2014-12-01

    With a focus on optical lattice gas heating, direct simulation Monte Carlo was used to investigate the interaction between molecular nitrogen, argon and methane, initially at 300 K and 0.8 atm, with pulsed, chirped optical lattices. Created from two 700 mJ, 532 nm, flattop laser pulses, the optical lattice parameters simulated are based on published optical lattice-based experiments, to ensure that pulse energies and durations do not exceed published optical breakdown (ionization) thresholds. Resultant translational gas temperatures, as well as induced bulk velocities, were used quantify energy and momentum deposition. To maximize available gas temperature changes achieved using the technique, laser pulses were linearly chirped to produce lattice velocities able to more effectively facilitate energy deposition throughout the pulse duration. From the initial conditions, the maximum, end pulse axial translational temperature obtained in nitrogen was approximately 755 K, at a lattice velocity of 400 m/s linearly chirped at 25 Gm/s2 over the 40 ns pulse duration. To date, this stands as the single largest, numerically-predicted temperature change from optical lattice gas heating under the numerical integration of real world energy and laser-based limitations.

  10. Chirp Z-transform spectral zoom optimization with MATLAB.

    SciTech Connect

    Martin, Grant D.

    2005-11-01

    The MATLAB language has become a standard for rapid prototyping throughout all disciplines of engineering because the environment is easy to understand and use. Many of the basic functions included in MATLAB are those operations that are necessary to carry out larger algorithms such as the chirp z-transform spectral zoom. These functions include, but are not limited to mathematical operators, logical operators, array indexing, and the Fast Fourier Transform (FFT). However, despite its ease of use, MATLAB's technical computing language is interpreted and thus is not always capable of the memory management and performance of a compiled language. There are however, several optimizations that can be made within the chirp z-transform spectral zoom algorithm itself, and also to the MATLAB implementation in order to take full advantage of the computing environment and lower processing time and improve memory usage. To that end, this document's purpose is two-fold. The first demonstrates how to perform a chirp z-transform spectral zoom as well as an optimization within the algorithm that improves performance and memory usage. The second demonstrates a minor MATLAB language usage technique that can reduce overhead memory costs and improve performance.

  11. Gaussian Decomposition of Laser Altimeter Waveforms

    NASA Technical Reports Server (NTRS)

    Hofton, Michelle A.; Minster, J. Bernard; Blair, J. Bryan

    1999-01-01

    We develop a method to decompose a laser altimeter return waveform into its Gaussian components assuming that the position of each Gaussian within the waveform can be used to calculate the mean elevation of a specific reflecting surface within the laser footprint. We estimate the number of Gaussian components from the number of inflection points of a smoothed copy of the laser waveform, and obtain initial estimates of the Gaussian half-widths and positions from the positions of its consecutive inflection points. Initial amplitude estimates are obtained using a non-negative least-squares method. To reduce the likelihood of fitting the background noise within the waveform and to minimize the number of Gaussians needed in the approximation, we rank the "importance" of each Gaussian in the decomposition using its initial half-width and amplitude estimates. The initial parameter estimates of all Gaussians ranked "important" are optimized using the Levenburg-Marquardt method. If the sum of the Gaussians does not approximate the return waveform to a prescribed accuracy, then additional Gaussians are included in the optimization procedure. The Gaussian decomposition method is demonstrated on data collected by the airborne Laser Vegetation Imaging Sensor (LVIS) in October 1997 over the Sequoia National Forest, California.

  12. University Policy No.: FM5205 Classification: Financial Management

    E-print Network

    Victoria, University of

    University Policy No.: FM5205 Classification: Financial Management CAPITAL EXPENDITURES on equipment, furniture, site development, utilities and landscaping) that are required to complete a building members, one of whom shall be the Executive Director of Facilities Management. The Executive Director

  13. University Policy No.: FM5105 Classification: Financial Management

    E-print Network

    Victoria, University of

    University Policy No.: FM5105 Classification: Financial Management Approving Authority: Board responsive and responsible source. Purchasing and supply management functions at the University of Victoria for acquiring goods, equipment, services and construction for all academic, administrative, and affiliated

  14. 75 FR 41092 - FM TABLE OF ALLOTMENTS, Kingsland, Texas

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-15

    ...to conform to the 1992 USA-Mexico FM Broadcast Agreement...copying during normal business hours in the FCC Reference...burden ``for small business concerns with fewer than...pursuant to the Small Business Paperwork Relief...

  15. Horizontal Branch stars as AmFm/HgMn stars

    E-print Network

    G. Michaud; J. Richer

    2008-02-12

    Recent observations and models for horizontal branch stars are briefly described and compared to models for AmFm stars. The limitations of those models are emphasized by a comparison to observations and models for HgMn stars.

  16. FM 4-02.19 DENTAL SERVICE SUPPORT OPERATIONS

    E-print Network

    US Army Corps of Engineers

    FM 4-02.19 July 2009 DENTAL SERVICE SUPPORT OPERATIONS DISTRIBUTION RESTRICTION: Approved of the Army Washington, DC, 31 July 2009 Dental Service Support Operations Contents Page PREFACE .............................................................................................................iv Chapter 1 OVERVIEW OF DENTAL SERVICE SUPPORT............................................... 1

  17. 72. Credit FM. Overview of powerhouse from gallery. Notice cooling ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. Credit FM. Overview of powerhouse from gallery. Notice cooling duct on generator (now removed) and spare gate valve in far corner. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  18. 68. Credit FM. Detail showing operators. Note cooling duct (now ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    68. Credit FM. Detail showing operators. Note cooling duct (now removed), governor (now removed), hand-operated needle valve controls (now removed). - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  19. 56. Credit FM. East elevation taken from along penstock. Note ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. Credit FM. East elevation taken from along penstock. Note additions to the east side and the north side of the building. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  20. 59. Credit FM. Flood waters on South Battle Creek next ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    59. Credit FM. Flood waters on South Battle Creek next to powerhouse. Note height of water in relation to tailraces. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  1. 75 FR 27977 - FM Table of Allotments, Fairbanks, Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-19

    ...RM-11600] FM Table of Allotments, Fairbanks, Alaska AGENCY: Federal Communications...thirteenth and fourteenth local service at Fairbanks, Alaska. Both stations can be allotted at Fairbanks in compliance with the Commission's...

  2. Extraction of phase nonlinearities from an FM radar system

    E-print Network

    Weigel, Henry Samuel

    1986-01-01

    EXTRACTION OF PHASE NONLINEARITIES FROM AN FM RADAR SYSTEM A Thesis by HENRY SAMUEL WEIGEL IV Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December... 19B6 Major Subject: Electrical Engineering EXTRACTION OF PHASE NONLINEARITIES FROM AN FM RADAR SYSTEM A Thesis by HENRY SAMUEL WEIGEL IV Approved as to style and content by: Dr. R. W. Newton (Co-Chairman of Committee) D . B. R. Jean (Co...

  3. Wavelet analysis of the impedance cardiogram waveforms

    NASA Astrophysics Data System (ADS)

    Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.

    2012-12-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  4. The Focusing DIRC with Waveform Digitizing Electronics

    SciTech Connect

    Ruckman, L.L.; /Hawaii U.; Nishimura, K.; /Hawaii U.; Varner, G.S.; /Hawaii U.; Vavra, J.; /SLAC; Aston, D.; /SLAC; Leith, D.W.G.S.; /SLAC; Ratcliff, B.; /SLAC

    2012-06-15

    We have tested a novel Cherenkov imaging detector called the Focusing DIRC (FDIRC) with waveform digitizing electronics. The prototype's concept is based on the BaBar DIRC with several important improvements: (a) much faster, pixelated photon detectors, (b) a mirror that makes the photon detector smaller and less sensitive to background in future applications, and (c) electronics capable of measuring single photon resolution to {sigma} {approx} 150 ps, which allows for correction due to chromatic error. In this test, the prototype has been instrumented with seven Hamamatsu H-8500 MaPMTs. Waveforms from {approx}450 pixels are digitized with waveform sampling electronics based on the BLAB2 ASIC, operating at a sampling speed of {approx}2.5 GSa/s. This version of the FDIRC prototype was tested in a large cosmic ray telescope providing muon tracks with {approx}1 mrad angular resolution and a muon momentum cutoff of {ge} 1.6 GeV/c.

  5. 47 CFR 73.827 - Interference to the input signals of FM translator or FM booster stations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...translator station's receive antenna. (2) Complies with the minimum LPFM/FM translator distance separation calculated in accordance with the following formula: du = 133.5 antilog [(Peu + Gru ? Grd ? Ed )/20], where du =...

  6. 47 CFR 73.827 - Interference to the input signals of FM translator or FM booster stations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...below 34 dB at all locations, (2) Complies with the minimum LPFM/FM translator distance separation calculated in accordance with the following formula: du = 133.5 antilog [(Peu + Gru ? Grd ? Ed )/20], where du =...

  7. Quasi-orthogonal wideband radar waveforms based on chaotic systems

    E-print Network

    Willsey, Matt (Matt S.)

    2007-01-01

    With the development of A/D converters possessing sufficiently high sampling rates, it is now feasible to use arbitrary, wideband waveforms in radar applications. Large sets of quasi-orthogonal, wideband waveforms can be ...

  8. Radar altimeter waveform modeled parameter recovery. [SEASAT-1 data

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Satellite-borne radar altimeters include waveform sampling gates providing point samples of the transmitted radar pulse after its scattering from the ocean's surface. Averages of the waveform sampler data can be fitted by varying parameters in a model mean return waveform. The theoretical waveform model used is described as well as a general iterative nonlinear least squares procedures used to obtain estimates of parameters characterizing the modeled waveform for SEASAT-1 data. The six waveform parameters recovered by the fitting procedure are: (1) amplitude; (2) time origin, or track point; (3) ocean surface rms roughness; (4) noise baseline; (5) ocean surface skewness; and (6) altitude or off-nadir angle. Additional practical processing considerations are addressed and FORTRAN source listing for subroutines used in the waveform fitting are included. While the description is for the Seasat-1 altimeter waveform data analysis, the work can easily be generalized and extended to other radar altimeter systems.

  9. Focal Mechanism Determination using High Frequency, Full Waveform Information

    E-print Network

    Li, Junlun

    2009-01-01

    In this research, we use high frequency waveform information to determine the focal mechanisms of small local earthquakes at an oil reservoir. During the waveform inversion, we maximize both the phase and amplitude matching ...

  10. JTRS/SCA and Custom/SDR Waveform Comparison

    NASA Technical Reports Server (NTRS)

    Oldham, Daniel R.; Scardelletti, Maximilian C.

    2007-01-01

    This paper compares two waveform implementations generating the same RF signal using the same SDR development system. Both waveforms implement a satellite modem using QPSK modulation at 1M BPS data rates with one half rate convolutional encoding. Both waveforms are partitioned the same across the general purpose processor (GPP) and the field programmable gate array (FPGA). Both waveforms implement the same equivalent set of radio functions on the GPP and FPGA. The GPP implements the majority of the radio functions and the FPGA implements the final digital RF modulator stage. One waveform is implemented directly on the SDR development system and the second waveform is implemented using the JTRS/SCA model. This paper contrasts the amount of resources to implement both waveforms and demonstrates the importance of waveform partitioning across the SDR development system.

  11. A Fractional Fourier Transform Analysis of a Bubble Excited by an Ultrasonic Chirp

    E-print Network

    Mottram, Nigel

    A Fractional Fourier Transform Analysis of a Bubble Excited by an Ultrasonic Chirp Euan Barlow. 2 #12;1 Introduction When a bubble is insonified by an ultrasonic signal it oscillates perturbation of the bubble's radius to show that using an ultrasonic chirp signal as the forcing function

  12. Effects of Energy Chirp on Echo-Enabled Harmonic Generation Free-Electron Lasers

    SciTech Connect

    Huang, Z.; Ratner, D.; Stupakov, G.; Xiang, D.; /SLAC

    2009-02-23

    We study effects of energy chirp on echo-enabled harmonic generation (EEHG). Analytical expressions are compared with numerical simulations for both harmonic and bunching factors. We also discuss the EEHG free-electron laser bandwidth increase due to an energy-modulated beam and its pulse length dependence on the electron energy chirp.

  13. Light synthesis with linearly chirped fibre Bragg gratings (FBGs) for optical coherence tomography (OCT) applications

    Microsoft Academic Search

    Enock Jonathan

    2005-01-01

    A simple technique of using a combination of linearly chirped fibre Bragg gratings (FBGs) to generate light to enhance depth resolution in optical coherence tomography (OCT) is introduced. A [3×3] fused fibre coupler was used to couple and redistribute super luminescent diode (SLD) light to linearly chirped FBGs connected to the fibre output arms of the coupler. Reflected and\\/or transmitted

  14. Chirped pulse amplification of 300 fs pulses in an alexandrite regenerative amplifier

    Microsoft Academic Search

    Maurice Pessot; Jeff Squier; Philippe Bado; Gerard Mourou; Donald J. Harter

    1989-01-01

    The amplification of fsec dye-laser pulses up to the 3.5-mJ level in an alexandrite regenerative amplifier is discussed. An expansion\\/compression system using different gratings allows chirped amplification techniques to be used to produce peak powers upwards of 1 GW. Limitations in the chirped pulse amplification of ultrashort pulses due to intracavity dispersive elements are discussued.

  15. Passive coherent beam combining of two femtosecond fiber chirped-pulse amplifiers

    E-print Network

    Boyer, Edmond

    Passive coherent beam combining of two femtosecond fiber chirped-pulse amplifiers Louis Daniault,1 femtosecond chirped- pulse amplifiers. The setup consists in the use of a well-balanced amplifying Sagnac amplifiers have great advantages to amplify ultrashort femtosecond pulses. Indeed, their geometry offers

  16. Frequency chirp and pulse shape effects in self-modulated laser wakefield acceleratorsa...

    E-print Network

    Geddes, Cameron Guy Robinson

    Frequency chirp and pulse shape effects in self-modulated laser wakefield acceleratorsa... C. B Received 7 November 2002; accepted 20 January 2003 The effect of asymmetric laser pulses on plasma wave of asymmetries in frequency chirp and tempo- ral pulse shape on the laser-excitation of plasma waves. Sec- tion

  17. Frequency chirp and pulse shape effects in self-modulated laser wakefield accelerators

    Microsoft Academic Search

    C. B. Schroeder; E. Esarey; C. G. R. Geddes; Cs. Tóth; B. A. Shadwick; J. van Tilborg; J. Faure; W. P. Leemans

    2003-01-01

    The effect of asymmetric laser pulses on plasma wave excitation in a self-modulated laser wakefield accelerator is examined. Laser pulse shape and frequency chirp asymmetries, controlled experimentally in the laser system through a grating pair compressor, are shown to strongly enhance measured electron yields for certain asymmetries. It is shown analytically that a positive (negative) frequency chirp enhances (suppresses) the

  18. Frequency chirp and pulse shape effects in self-modulated laser wakefield accelerators

    Microsoft Academic Search

    C. B. Schroeder; E. Esarey; C. G. R. Geddes; Cs. Toth; B. A. Shadwick; J. van Tilborg; J. Faure; W. P. Leemans

    2002-01-01

    The effect of asymmetric laser pulses on plasma wave excitation in a self-modulated laser wakefield accelerator is examined. Laser pulse shape and frequency chirp asymmetries, controlled experimentally in the laser system through a grating pair compressor, are shown to strongly enhance measured electron yields for certain asymmetries. It is shown analytically that a positive (negative) frequency chirp enhances (suppresses) the

  19. Simple measurement of fiber dispersion and of chirp parameter of intensity modulated light emitter

    Microsoft Academic Search

    F. Devaux; Y. Sorel; J. F. Kerdiles

    1993-01-01

    We report a novel method to measure two important parameters for optical fiber intensity modulated transmission systems: dispersion of optical fibers and chirp parameter of modulated light emitters. The method is easy, quick, and accurate for chirp parameter in the -10-to-10 range

  20. Anim. Behav., 1997, 54, 15531562 Female house crickets, Acheta domesticus, prefer the chirps of large males

    E-print Network

    Gray, David A.

    Anim. Behav., 1997, 54, 1553­1562 Female house crickets, Acheta domesticus, prefer the chirps and analysed the calling songs of male house crickets, Acheta domesticus. The analyses showed that chirps choice and sperm com- petition (Møller 1994). Many of these components can be separated in field crickets

  1. Mono-bit digital chirp receiver using mono-bit IFM (instantaneous frequency measurement) receiver as a core

    Microsoft Academic Search

    David M. Lin; Lihyeh L. Liou; Steve Benson; Henry Chen

    2011-01-01

    This paper describes the design and intricacies of a wideband digital chirp receiver utilizing a one-bit ADC (Analog to Digital Converter) to measure the carrier frequency and chirp rate of unknown received signals which have very high chip rates. The core of the chirp receiver is composed of monobit IFM receivers which are low cost and very accurate.

  2. Superradiant Linear Raman Amplification in Plasma Using a Chirped Pump Pulse B. Ersfeld and D. A. Jaroszynski

    E-print Network

    Strathclyde, University of

    Superradiant Linear Raman Amplification in Plasma Using a Chirped Pump Pulse B. Ersfeld and D. A backscattering from a chirped pump pulse in plasma shows that an ultrashort probe pulse will grow superradiantly. Linear chirped pulse amplification in plasma could provide a very broad-bandwidth alternative to solid

  3. 3336 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 27, NO. 16, AUGUST 15, 2009 Chirped Microwave Pulse Generation Based on

    E-print Network

    Yao, Jianping

    Generation Based on Optical Spectral Shaping and Wavelength-to-Time Mapping Using a Sagnac Loop Mirror and the chirp profile of the generated chirped microwave pulse can be controlled by simply tuning the time delay in the Sagnac loop mirror. A simple mathematical model to describe the chirped microwave pulse generation

  4. Experimental demonstration of a multi-wavelength distributed feedback semiconductor laser array with an equivalent chirped grating profile based on the equivalent chirp technology.

    PubMed

    Li, Wangzhe; Zhang, Xia; Yao, Jianping

    2013-08-26

    We report, to the best of our knowledge, the first realization of a multi-wavelength distributed feedback (DFB) semiconductor laser array with an equivalent chirped grating profile based on equivalent chirp technology. All the lasers in the laser array have an identical grating period with an equivalent chirped grating structure, which are realized by nonuniform sampling of the gratings. Different wavelengths are achieved by changing the sampling functions. A multi-wavelength DFB semiconductor laser array is fabricated and the lasing performance is evaluated. The results show that the equivalent chirp technology is an effective solution for monolithic integration of a multi-wavelength laser array with potential for large volume fabrication. PMID:24105542

  5. Improving service delivery in FM: case study of a UK hospital facilities directorate

    Microsoft Academic Search

    M. Sarshar

    2006-01-01

    Purpose – The purpose of this paper is to describe a case study of SPICE FM implementation in the Facilities Directorate of a major UK hospital. SPICE FM is a process improvement framework for FM organisations, which was developed through university research in the UK. SPICE FM identified strengths and weaknesses of the facilities operation and provides specific guidelines for

  6. Dynamic optical arbitrary waveform generation and measurement

    E-print Network

    Kolner, Brian H.

    Dynamic optical arbitrary waveform generation and measurement Ryan P. Scott,* Nicolas K. Fontaine, Jonathan P. Heritage, and S. J. B. Yoo Department of Electrical and Computer Engineering, University(7), 2701­2719 (2006). 4. N. K. Fontaine, R. P. Scott, J. Cao, A. Karalar, W. Jiang, K. Okamoto, J. P

  7. Parameter Estimation using Numerical Merger Waveforms

    NASA Technical Reports Server (NTRS)

    Thorpe, J. I.; McWilliams, S.; Kelly, B.; Fahey, R.; Arnaud, K.; Baker, J.

    2008-01-01

    Results: Developed parameter estimation model integrating complete waveforms and improved instrumental models. Initial results for equal-mass non-spinning systems indicate moderate improvement in most parameters, significant improvement in some Near-term improvement: a) Improved statistics; b) T-channel; c) Larger parameter space coverage. Combination with other results: a) Higher harmonics; b) Spin precession; c) Instrumental effects.

  8. Waveform Selectivity at the Same Frequency

    PubMed Central

    Wakatsuchi, Hiroki; Anzai, Daisuke; Rushton, Jeremiah J.; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F.

    2015-01-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of circuit elements are then combined to absorb or transmit specific waveforms in between. This waveform selectivity gives us another degree of freedom to control electromagnetic waves in various fields including wireless communications, as our simulation reveals that the metasurfaces are capable of varying bit error rates in response to different waveforms. PMID:25866071

  9. Efficient waveform recall in absorbing media

    Microsoft Academic Search

    Carrie S. Cornish; Mohammad Azadeh; W. Randall Babbitt; Leung Tsang

    1998-01-01

    We have found that highly efficient waveform recall is possible in coherent transient systems in which the storage is optically thick. Coherent transients may be used in a variety of information storage and processing applications with advantages over traditional electronic methods. However, it is believed that a serious problem in application of photon echoes in practical systems is the relatively

  10. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

    SciTech Connect

    Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

    2008-06-17

    Earthquake source parameters underpin several aspects of nuclear explosion monitoring. Such aspects are: calibration of moment magnitudes (including coda magnitudes) and magnitude and distance amplitude corrections (MDAC); source depths; discrimination by isotropic moment tensor components; and waveform modeling for structure (including waveform tomography). This project seeks to improve methods for and broaden the applicability of estimating source parameters from broadband waveforms using the Cut-and-Paste (CAP) methodology. The CAP method uses a library of Green’s functions for a one-dimensional (1D, depth-varying) seismic velocity model. The method separates the main arrivals of the regional waveform into 5 windows: Pnl (vertical and radial components), Rayleigh (vertical and radial components) and Love (transverse component). Source parameters are estimated by grid search over strike, dip, rake and depth and seismic moment or equivalently moment magnitude, MW, are adjusted to fit the amplitudes. Key to the CAP method is allowing the synthetic seismograms to shift in time relative to the data in order to account for path-propagation errors (delays) in the 1D seismic velocity model used to compute the Green’s functions. The CAP method has been shown to improve estimates of source parameters, especially when delay and amplitude biases are calibrated using high signal-to-noise data from moderate earthquakes, CAP+.

  11. A transformer of closely spaced pulsed waveforms

    NASA Technical Reports Server (NTRS)

    Niedra, J.

    1970-01-01

    Passive circuit, using diodes, transistors, and magnetic cores, transforms the voltage of repetitive positive or negative pulses. It combines a pulse transformer with switching devices to effect a resonant flux reset and can transform various pulsed waveforms that have a nonzero average value and are relatively cosely spaced in time.

  12. Waveform selectivity at the same frequency.

    PubMed

    Wakatsuchi, Hiroki; Anzai, Daisuke; Rushton, Jeremiah J; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F

    2015-01-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of circuit elements are then combined to absorb or transmit specific waveforms in between. This waveform selectivity gives us another degree of freedom to control electromagnetic waves in various fields including wireless communications, as our simulation reveals that the metasurfaces are capable of varying bit error rates in response to different waveforms. PMID:25866071

  13. Adaptive RF-photonic arbitrary waveform generator

    Microsoft Academic Search

    Jason Chou; Yan Han; Bahram Jalali

    2003-01-01

    Optical and radio-frequency waveforms with wide-band arbitrary modulation are generated using spectral shaping of a supercontinuum source followed by wavelength-to-time mapping. Adaptive computer control is used to mitigate the nonideal features inherent in the optical source and in the spectrum modulation process.

  14. Optimal adaptive waveform selection for target detection

    Microsoft Academic Search

    B. F. La Scala; W. Moran; R. J. Evans

    2003-01-01

    Modern phased array radars are able to adaptively modify their performance to the environment. To make full use of this capability, scheduling algorithms need to be designed. This paper poses the problem of adaptive waveform scheduling for detecting new targets in the context of finite horizon stochastic dynamic programming. The result is a scheduling algorithm that minimises the time taken

  15. Transverse-to-longitudinal Emittance-exchange with an Energy Chirped Beam

    SciTech Connect

    Thangaraj, J.; Ruan, J.; Johnson, A.S.; Thurman-Keup, R.; Lumpkin, A.H.; Santucci, J.; Sun, Y.-E; Maxwell, T.; Edwards, H.; /Fermilab

    2012-05-01

    Emittance exchange has been proposed to increase the performance of free electron lasers by tailoring the phase space of an electron beam. The principle of emittance exchange - where the transverse phase space of the electron beam is exchanged with the longitudinal phase space - has been demonstrated recently at the A0 photoinjector. The experiment used a low charge bunch (250 pC) with no energy chirp. Theory predicts an improvement in the emittance exchange scheme when the incoming beam has an energy chirp imparted on it. The energy chirp helps to overcome the thick lens effect of the deflecting mode cavity and other second order effects that might lead to an incomplete emittance exchange at higher charges. In this work, we report experimental and simulation results from operating the emittance exchange beam line using an energy chirped beam with higher charge (500 pC) at different RF-chirp settings.

  16. CE-Chirp® ABR in cerebellopontine angle surgery neuromonitoring: technical assessment in four cases.

    PubMed

    Di Scipio, Ettore; Mastronardi, Luciano

    2015-04-01

    Continuous monitoring of wave V of auditory brainstem response (ABR), also called brainstem auditory evoked potential (BAEP), is the most common method used in intraoperative neuromonitoring (IONM) functionality of cochlear nerve during surgery in cerebellopontine angle (CPA). CE-Chirp® ABR represents a recent development of classical ABR. CE-Chirp® is a new acoustic stimulus used in newborn hearing testing, designed to provide enhanced neural synchronicity and faster detection of larger amplitude wave V. In four cases, CE-Chirp® ABR was performed during cerebellopontine angle (CPA) surgery. CE-Chirp® ABR represented a safe and effective method in neuromonitoring functionality of vestibulocochlear nerve. A faster neuromonitoring feedback to surgical equipe was possible with CE-Chirp ABR®. PMID:25697141

  17. Backward Raman amplification in plasmas with chirped wideband pump and seed pulses

    NASA Astrophysics Data System (ADS)

    Wu, Zhao-Hui; Wei, Xiao-Feng; Zuo, Yan-Lei; Liu, Lan-Qin; Zhang, Zhi-Meng; Li, Min; Zhou, Yu-Liang; Su, Jing-Qin

    2015-01-01

    Chirped wideband pump and seed pulses are usually considered for backward Raman amplification (BRA) in plasmas to achieve an extremely high-power laser pulse. However, current theoretical models only contain either a chirped pump or a chirped seed. In this paper, modified three-wave coupling equations are proposed for the BRA in the plasmas with both chirped wideband pump and seed. The simulation results can more precisely describe the experiments, such as the Princeton University experiment. The optimized chirp and bandwidth are determined based on the simulation to enhance the output intensity and efficiency. Project supported by the National Natural Science Foundation of China (Grant No. 11305157) and the Development Foundation of China Academy of Engineering Physics Laboratory (CAEPL) (Grant No. 2013A0401019).

  18. Chirped Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows

    NASA Astrophysics Data System (ADS)

    Abeysekera, Chamara; Oldham, James; Prozument, Kirill; Joalland, Baptiste; Park, Barratt; Field, Robert W.; Sims, Ian; Suits, Arthur; Zack, Lindsay

    2014-06-01

    We present preliminary results describing the development of a new instrument that combines two powerful techniques: Chirped Pulse-Fourier Transform MicroWave (CP-FTMW) spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates and perform unique spectroscopic, kinetics and dynamics measurements. We have constructed a new high-power K_a-band, 26-40 GHz, chirped pulse spectrometer with sub-MHz resolution, analogous to the revolutionary CP-FTMW spectroscopic technique developed in the Pate group at University of Virginia. In order to study smaller molecules, the E-band, 60-90 GHz, CP capability was added to our spectrometer. A novel strategy for generating uniform supersonic flow through a Laval nozzle is introduced. High throughput pulsed piezo-valve is used to produce cold (30 K) uniform flow with large volumes of 150 cm^3 and densities of 1014 molecules/cm3 with modest pumping facilities. The uniform flow conditions for a variety of noble gases extend as far as 20 cm from the Laval nozzle and a single compound turbo-molecular pump maintains the operating pressure. Two competing design considerations are critical to the performance of the system: a low temperature flow is needed to maximize the population difference between rotational levels, and high gas number densities are needed to ensure rapid cooling to achieve the uniform flow conditions. At the same time, collision times shorter than the chirp duration will give inaccurate intensities and reduced signal levels due to collisional dephasing of free induction decay. Details of the instrument and future directions and challenges will be discussed.

  19. Chirped laser dispersion spectroscopy with differential frequency generation source.

    PubMed

    Nikodem, Michal; Krzempek, Karol; Karwat, Renata; Dudzik, Grzegorz; Abramski, Krzysztof; Wysocki, Gerard

    2014-08-01

    A feasibility study of open-path methane detection at 3.4 ?m using chirped laser dispersion spectroscopy (CLaDS) based on nonlinear differential frequency generation (DFG) laser source is performed. Application of a DFG source based on telecom laser sources and modulators allows mid-infrared CLaDS system to be optimized for measurements of gases at atmospheric conditions for which modulation in the GHz range is required. Excellent agreement between observed CLaDS signals and spectroscopic models has been observed. PMID:25078192

  20. Attenuated total reflectance spectroscopy with chirped-pulse upconversion.

    PubMed

    Shirai, Hideto; Duchesne, Constance; Furutani, Yuji; Fuji, Takao

    2014-12-01

    Chirped-pulse upconversion technique has been applied to attenuated total reflectance (ATR) infrared spectroscopy. An extremely broadband infrared pulse was sent to an ATR diamond prism and the reflected pulse was converted to the visible by using four-wave mixing in krypton gas. Absorption spectra of liquids in the range from 200 to 5500 cm(-1) were measured with a visible spectrometer on a single-shot basis. The system was applied to observe the dynamics of exchanging process of two solvents, water and acetone, which give clear vibrational spectral contrast. We observed that the exchange was finished within ? 10 ms. PMID:25606893

  1. Design of arbitrary waveform generator based on SDRAM

    Microsoft Academic Search

    Daqiang Qiu; Qunzhan Li; Fuling Zhou

    2009-01-01

    To solve the problems of the difficulty to generate long period waveform, of the complicated operation and inconvenient control, a scheme that is based on the combination of large capacity storage and virtual instruments technique of arbitrary waveform generator (AWG), is proposed. The storage capacity has been raised up to 8M by utilizing synchronous DRAM (SDRAM) as a waveform data

  2. Agilent 33210A 10 MHz Function/Arbitrary Waveform Generator

    E-print Network

    California at San Diego, University of

    Agilent 33210A 10 MHz Function/Arbitrary Waveform Generator Data Sheet · 10 MHz Sine and Square at an affordable price The Agilent Technologies 33210A Function/Arbitrary Waveform Generator is the latest addition- volatile memory. The Agilent IntuiLink Arbitrary Waveform software allows you to easily create, edit

  3. Bazhen Fm matured reservoir evaluation (West Siberia, Russia)

    NASA Astrophysics Data System (ADS)

    Parnachev, S.; Skripkin, A.; Baranov, V.; Zakharov, S.

    2015-02-01

    The depletion of the traditional sources of hydrocarbons leads to the situation when the biggest players of the oil and gas production market turn to unconventional reserves. Commercial shale oil and gas production levels in the USA have largely determined world prospects for oil and gas industry development. Russia takes one of the leading place in the world in terms of shale oil resources. The main source rock of the West Siberia, the biggest oil and gas basin in Russia under development, the Bazhen Fm and its stratigraphic and lithologic analogs, is located in the territory of over 1,000,000 square kilometers. Provided it has similar key properties (organic carbon content, porosity, permeability) with the deposits of the Bakken Fm and Green River Fm, USA, it is still extremely poorly described with laboratory methods. We have performed the laboratory analysis of core samples from a well drilled in Bazhen Fm deposits with matured organic matter (Tmax>435 °C). It was demonstrated the applicability of the improved steady-state gas flow method to evaluate the permeability of nanopermeable rocks. The role of natural fracturing in forming voids was determided that allows regarding potential Bazhen Fm reservoirs as systems with dual porosity and dual permeability.

  4. Research on a kind of high precision and fast signal processing algorithm for FM/CW laser radar

    NASA Astrophysics Data System (ADS)

    Xu, Xinke; Liu, Guodong; Chen, Fengdong; Liu, Bingguo; Zhuang, Zhitao; Lu, Cheng; Gan, Yu

    2014-12-01

    Range accuracy and efficiency are two important indicators for Frequency modulated continuous wave (FM/CW) laser radar, improving the accuracy and efficiency of extracting beat frequency are key factors for them. Multiple Modulation Zoom Spectrum Analysis (ZFFT) and the Chirp-Z Transform (CZT) are two widely used methods for improving frequency estimation. The paper through analyze advantages and disadvantages of these methods, proposes a high accuracy and fast signal processing method which is ZFFT-CZT, it combines advantages that ZFFT can reduce data size, and CZT can zoom in frequency of any interested band. The processing of ZFFT-CZT is following: firstly ZFFT is conducted by conducting Fourier transform on short time signal to calculate amount of frequency shift, and transforming high-frequency signal into low-frequency signal of long time sampling, then CZT is conducted by choosing any interested band to continue subdividing the spectral peaks, which can reduce picket fence effect. By simulate experiment based on ZFFT-CZT method, two closed targets at distance of 50m and 50.001m are measured, and the measurement errors are 40?m and 34?m respectively. It proved that ZFFT-CZT has a small amount of calculation, which can meet the requirement of high precision frequency extraction.

  5. Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential

    NASA Astrophysics Data System (ADS)

    Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai

    2012-02-01

    Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

  6. An improved high-voltage waveform generator

    Microsoft Academic Search

    P. T. Krein; D. J. Kervin; J. M. Crowley

    1983-01-01

    An improved high-voltage low-frequency waveform generator is described. It is based on a design by Miller et al. (1975) with the addition of a feedback control loop. The device can supply up to 27 kV and 2 mA from 0-100 Hz, and up to 10 kV at 1 kHz. Total harmonic distortion is reduced from the earlier device to under

  7. Resolution Analysis in Full Waveform Inversion

    NASA Astrophysics Data System (ADS)

    Fichtner, A.; Trampert, J.

    2011-12-01

    Full waveform inversion is a tomographic technique that is based on numerical wave propagation through complex media combined with adjoint or scattering integral methods for the computation of Fréchet kernels. While the tomographic method itself has advanced substantially, an essential aspect of the inverse problem has been ignored almost completely: The quantification of resolution and uncertainties. We propose a new method for the quantitative resolution analysis in full seismic waveform inversion that overcomes the limitations of synthetic inversions while being computationally more efficient and applicable to any misfit measure. The method rests on (1) the local quadratic approximation of the misfit functional in the vicinity of an optimal Earth model, (2) the parametrisation of the Hessian in terms of a parent function, and (3) the computation of the space-dependent parameters via Fourier transforms of the Hessian, calculated with the help of adjoint techniques. In the simplest case of a Gaussian approximation we can infer rigorously defined 3D distributions of direction-dependent resolution lengths and the image distortion introduced by the tomographic method. We illustrate these concepts with a realistic full waveform inversion for upper-mantle structure beneath Europe. As a corollary to the method for resolution analysis we propose several improvements to full waveform inversion techniques. These include a pre-conditioner for optimisation schemes of the conjugate-gradient type, a new family of Newton-like methods, an approach to adaptive parametrisation independent from ray theory, and a strategy for objective functional design that aims at maximising resolution. The computational requirements of our approach are less than for a typical synthetic inversion, but yield a much more complete picture of resolution and trade-offs. It allows for adaptations to exploration scenarios and other wave equation based tomography techniques that employ, for instance, georadar or microwave data.

  8. MIMO Radar Waveform Constraints for GMTI

    Microsoft Academic Search

    K. W. Forsythe; D. W. Bliss

    2010-01-01

    Ground moving-target indication (GMTI) provides both an opportunity and challenge for coherent multiple-input multiple-output (MIMO) radar. MIMO techniques can improve a radar's angle estimation and the minimum detectable velocity (MDV) for a target. However, the challenge of clutter mitigation places significant constraints on MIMO radar waveforms. In this paper, the loss of target return because of clutter mitigation (signal-to-noise ratio

  9. Design of chirped fly's eye uniformizer for ArF lithography illumination system

    NASA Astrophysics Data System (ADS)

    Xiao, Lei; Li, Yanqiu; Wei, Lidong

    2014-11-01

    Fly's eye uniformizer is the key part of ArF lithography illumination system, whose main function is to illuminate the reticle uniformly. Due to the periodic structure of regular fly's eye uniformizer and the high coherence of the ArF laser, the output intensity distribution is modulated with equidistant sharp intensity peaks (interference speckle pattern) which disturbed the uniformity on the reticle. In this paper, we design a chirped fly's eye uniformizer which consists of chirped fly's eye and a condenser for illumination system in ArF lithography system. The chirped fly's eye consists of individually shaped micro-lenses defined by a parametric description which can be derived completely from analytical functions. The micro-lenses with different thicknesses in the chirped fly's eye have a function of delaying the optical path which reducing the laser coherence and speckle pattern on the reticle. Detailed design process of the chirped fly's eye uniformizer for numerical aperture (NA) 0.75 lithography illumination system is presented. Light intensity distribution on reticle produced by regular and chirped fly's eye uniformizer are analyzed and compared by the method of wave optics, and the results show that chirped can restrain sharp intensity peaks efficiently. Furthermore, the chirped fly's eye uniformizer has been traced in LightTools software under conventional and annual illumination modes, and the non-uniformity of the non-scan and scan direction on the reticle reached 0.75% and 1.24% respectively. The simulation results show that the chirped fly's eye uniformizer can provide high illumination uniformity and reduce the speckle pattern efficiently without additional elements.

  10. Satellite and Instrument Influences on ICESat Waveforms

    NASA Astrophysics Data System (ADS)

    Webb, C. E.; Urban, T. J.; Neuenschwander, A. L.; Gutierrez, R.; Schutz, B. E.

    2007-12-01

    The White Sands Space Harbor (WSSH) has served as the principal ground calibration site throughout the Ice, Cloud and land Elevation Satellite (ICESat) mission. The Center for Space Research (CSR) at the University of Texas at Austin continues to conduct various experiments designed to validate the timing, geolocation and geometric characteristics of individual laser footprints on the surface. In addition, two airborne lidar surveys of the calibration site and surrounding area were conducted during the mission, first in 2003 and again in 2007. Chosen for its limited surface roughness and topographic flatness, this area has been targeted 3-4 times in each of the 12 ICESat mapping campaigns to date, yielding a significant altimetry data set. The derived surface elevations are compared with those from the airborne lidar surveys, as well as those obtained by the Shuttle Radar Topography Mission (SRTM). Furthermore, the Geoscience Laser Altimetry System (GLAS) onboard ICESat records a digitized waveform for each laser pulse returned from the surface. The two methods currently used to fit such signals in ICESat data processing are examined and compared for the WSSH waveforms. The first fits up to two distinct Gaussians and provides a surface elevation at the location of the maximum peak. The second fits up to six overlapping Gaussians and provides a surface elevation at the centroid of the pulse. Observed differences in the reported elevations are discussed in terms of the satellite's off-nadir targeting geometry, the laser energy, and the skewness of the returned waveforms.

  11. Peculiarities of laser phase behavior associated with the accelerated electron in a chirped laser pulse

    SciTech Connect

    Song, Q.; Wu, X. Y. [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education and Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433 (China); Wang, J. X. [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education and Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433 (China); State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062 (China); Kawata, S. [Center for Optical Research and Education, Department of Advanced Interdisciplinary Science, Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585 (Japan); Wang, P. X., E-mail: wpx@fudan.edu.cn [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education and Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433 (China); Center for Optical Research and Education, Department of Advanced Interdisciplinary Science, Graduate School of Engineering, Utsunomiya University, Utsunomiya 321-8585 (Japan)

    2014-05-15

    In this paper, we qualitatively analyzed peculiarities of laser phase behavior associated with the accelerated electron in a chirped laser pulse. We unveiled the relationship between the changes in the orientation of the electron trajectory and the cusps in magnitude of the phase velocity of the optical field along the electron trajectory in a chirped laser pulse. We also explained how the chirp effect induced the singular point of the phase velocity. Finally, we discussed the phase velocity and phase witnessed by the electron in the particle's moving instantaneous frame.

  12. Self-deflecting plasmonic lattice solitons and surface modes in chirped plasmonic arrays

    NASA Astrophysics Data System (ADS)

    Li, Chunyan; Cui, Ran; Ye, Fangwei; Kartashov, Yaroslav V.; Torner, Lluis; Chen, Xianfeng

    2015-03-01

    We show that chirped metal-dielectric waveguide arrays with focusing cubic nonlinearity can support plasmonic lattice solitons that undergo self-deflection in the transverse plane. Such lattice solitons are deeply-subwavelength self-sustained excitations, although they cover several periods of the array. Upon propagation,the excitations accelerate in the transverse plane and follow trajectories curved in the direction in which the separation between neighboring metallic layers decreases, a phenomenon that yields considerable deflection angles. The deflection angle can be controlled by varying the array chirp. We also reveal the existence of surface modes at the boundary of truncated plasmonic chirped arraythat form even in the absence of nonlinearity.

  13. Control of optical properties of hybrid materials with chirped femtosecond laser pulses under strong coupling conditions.

    PubMed

    Sukharev, Maxim

    2014-08-28

    The interaction of chirped femtosecond laser pulses with hybrid materials--materials comprised of plasmon sustaining structures and resonant molecules--is scrutinized using a self-consistent model of coupled Maxwell-Bloch equations. The optical properties of such systems are examined with the example of periodic sinusoidal gratings. It is shown that under strong coupling conditions one can control light transmission using chirped pulses in a spatiotemporal manner. The temporal origin of control relies on chirps non-symmetric in time while the space control is achieved via spatial localization of electromagnetic energy due to plasmon resonances. PMID:25173035

  14. Self-deflecting plasmonic lattice solitons and sur-face modes in chirped plasmonic arrays

    E-print Network

    Li, Chunyan; Ye, Fangwei; Kartashov, Yaroslav V; Torner, Lluis; Chen, Xianfeng

    2015-01-01

    We show that chirped metal-dielectric waveguide arrays with focusing cubic nonlinearity can support plasmonic lattice solitons that undergo self-deflection in the transverse plane. Such lattice solitons are deeply-subwavelength self-sustained excitations, although they cover several periods of the array. Upon propagation,the excitations accelerate in the transverse plane and follow trajectories curved in the direction in which the separation between neighboring metallic layers decreases, a phenomenon that yields considerable deflection angles. The deflection angle can be controlled by varying the array chirp. We also reveal the existence of surface modes at the boundary of truncated plasmonic chirped arraythat form even in the absence of nonlinearity.

  15. Automated Chirp Detection with Diffusion Entropy: Application to Infrasound from Sprites

    E-print Network

    Ignaccolo, M; Farges, T; Fullekrug, M

    2005-01-01

    We study the performance of three different methods to automatically detect a chirp in background noise. (1) The standard deviation detector uses the computation of the signal to noise ratio. (2) The spectral covariance detector is based on the recognition of the chirp in the spectrogram. (3) The CASSANDRA detector uses diffusion entropy analysis to detect periodic patterns in noise. All three detectors are applied to an infrasound recording for detecting chirps produced by sprites. The CASSANDRA detector provides the best trade off between the false alarm rate and the detection efficiency.

  16. 75 FR 13236 - FM Table of Allotments, Port Angeles, Washington

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ...RM-11481] FM Table of Allotments, Port Angeles, Washington AGENCY: Federal Communications...Channel 271A for vacant Channel 229A at Port Angeles, Washington. DATES: Effective March...that the channel substitution at Port Angeles serves the public interest because...

  17. INDIRECT COSTS OF RESEARCH University Policy No: FM5400

    E-print Network

    Victoria, University of

    , animal care and environmental assessment). 5.00 Research Funding Agreement means funding provided through1 INDIRECT COSTS OF RESEARCH University Policy No: FM5400 Classification: Financial Management Research Funding Agreements PURPOSE 1.00 The purpose of this policy is to set out the principles for making

  18. College of Medicine FM Family and Community Medicine

    E-print Network

    MacAdam, Keith

    College of Medicine FM Family and Community Medicine KEY: # = new course * = course changed, FAMILY MEDICINE. (1-3) With the advice and approval of his or her faculty adviser, the first-year student may choose approved electives offered by the Department of Family and Community Medicine. The intent

  19. KDD IN FM: KNOWLEDGE DISCOVERY IN FACILITIES MANAGEMENT DATABASES

    E-print Network

    Coenen, Frans

    , the first ques­ tion faced by the practitioner is, which of these are most likely to be effective in that they have evolved within the organisation over a long period of time; as such they tend to be large practitioners wishing to apply KDD to FM (and a necessary prerequisite to data mining) is how to address

  20. Femtosecond Chirp-Free Transient Absorption Method And Apparatus

    DOEpatents

    McBranch, Duncan W. (Santa Fe, NM); Klimov, Victor I. (White Rock, NM)

    2001-02-20

    A method and apparatus for femtosecond transient absorption comprising phase-sensitive detection, spectral scanning and simultaneous controlling of a translation stage to obtain TA spectra information having at least a sensitivity two orders of magnitude higher than that for single-shot methods, with direct, simultaneous compensation for chirp as the data is acquired. The present invention includes a amplified delay translation stage which generates a splittable frequency-doubled laser signal at a predetermined frequency f, a controllable means for synchronously modulating one of the laser signals at a repetition rate of f/2, applying the laser signals to a material to be sample, and acquiring data from the excited sample while simultaneously controlling the controllable means for synchronously modulating.

  1. Chirped-Pulse Fourier Transform Microwave Spectroscopy of 3-METHOXYPROPYLAMINE

    NASA Astrophysics Data System (ADS)

    McCabe, Morgan N.; Shipman, Steven; Arnold, Sean; Chewning, J. Chase; Smith, Miranda; Brown, Gordon

    2014-06-01

    The rotational spectrum of 3-methoxypropylamine was collected from 8.0 to 18.5 GHz with the Coker College chirped-pulse FTMW molecular beam spectrometer. Ab initio predictions using the B3LYP-D3 dispersion-corrected density functional gave high quality starting geometries, enabling us to quickly assign the spectrum of the lowest energy conformer, which has a g'gt configuration (moving from the amine end to the methoxy end of the molecule). Attempts were also made to collect the spectrum of this molecule in the room-temperature waveguide instrument at New College, but these attempts were unsuccessful as the molecule rapidly reacts with the copper walls of the waveguide to produce ammonia.

  2. Chirped-pulse millimeter-wave spectroscopy: Spectrum, dynamics, and manipulation of Rydberg–Rydberg transitions

    E-print Network

    Colombo, Anthony P.

    2013-01-01

    We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of Rydberg–Rydberg transitions is that they have enormous electric dipole transition ...

  3. Strain-independent temperature measurements using a standard and a Chirped fibre Bragg Grating

    Microsoft Academic Search

    Anbhawa Nand; Daniel J. Kitcher; Scott A. Wade; Greg W. Baxter; Rhys Jones; S. F. Collins

    2006-01-01

    Chirped fibre Bragg gratings (CFBGs) fabricated in hydrogenated plain telecom fibre have a temperature coefficient approximately 20% higher than standard FBGs with identical strain coefficients. Thus a simple technique for strain-independent temperature measurement is proposed.

  4. Theoretical analysis of third order interferometric autocorrelation signals for enhanced sensitivity towards pulse chirp and asymmetry

    NASA Astrophysics Data System (ADS)

    Sharma, P. K.; Pandey, S. L.

    2011-11-01

    In this paper, we report theoretical analysis of third order interferometric autocorrelation to achieve enhanced sensitivity towards pulse chirp and asymmetry. The analysis is based on interferometric correlative envelope (ICE) functions and ICE difference signals derived from interferometric autocorrelation signals. The third order ICE signals are compared with second order ICE signals obtained from a second order interferometric autocorrelation signals. It is shown that one out of six third order ICED signals may be used to obtain simultaneous detection and measurement of pulse chirp as well as pulse asymmetry of the chirped ultrashort laser pulse. This is in contrast to use of two out of three second order ICED signals for simultaneous detection of pulse chirp and asymmetry.

  5. Bubble-Based Acoustic Radiation Force Using Chirp Insonation to Reduce Standing Wave Effects

    PubMed Central

    Erpelding, Todd N.; Hollman, Kyle W.; O’Donnell, Matthew

    2007-01-01

    Bubble-based acoustic radiation force can measure local viscoelastic properties of tissue. High intensity acoustic waves applied to laser-generated bubbles induce displacements inversely proportional to local Young’s modulus. In certain instances, long pulse durations are desirable but are susceptible to standing wave artifacts, which corrupt displacement measurements. Chirp pulse acoustic radiation force was investigated as a method to reduce standing wave artifacts. Chirp pulses with linear frequency sweep magnitudes of 100, 200, and 300 kHz centered around 1.5 MHz were applied to glass beads within gelatin phantoms and laser-generated bubbles within porcine lenses. The ultrasound transducer was translated axially to vary standing wave conditions, while comparing displacements using chirp pulses and 1.5 MHz tone burst pulses of the same duration and peak rarefactional pressure. Results demonstrated significant reduction in standing wave effects using chirp pulses, with displacement proportional to acoustic intensity and bubble size. PMID:17306697

  6. The use of chirped pulse millimeter-wave spectroscopy in chemical dynamics and kinetics

    E-print Network

    Shaver, Rachel Glyn

    2013-01-01

    .Chirped-pulse millimeter wave (CPmmW) spectroscopy is a revolutionary technique that has taken advantage of advances in electronics to give high signal to noise broadband rotational spectra in a very short period of time ...

  7. Controlled spatiotemporal plasmon excitation of silver nanoparticles with chirped optical pulses

    Microsoft Academic Search

    T.-W. Lee; S. K. Gray

    2005-01-01

    Numerical studies of chirped optical pulses interacting with cone-shaped silver nanoparticles are discussed. We show how localized excitations on the nanoparticles can be generated and controlled in a spatiotemporal manner and discuss a potential application.

  8. Effective temporal resolution in pump-probe spectroscopy with strongly chirped pulses

    SciTech Connect

    Polli, D.; Lanzani, G. [IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); CNST, Istituto Italiano di Tecnologia, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Brida, D.; Cerullo, G. [IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Mukamel, S. [Chemistry Department, University of California, Irvine, Irvine, California 92697-2025 (United States)

    2010-11-15

    This paper introduces a general theoretical description of femtosecond pump-probe spectroscopy with chirped pulses whose joint spectral and temporal profile is expressed by Wigner spectrograms. We demonstrate that the actual experimental time resolution intimately depends on the pulse-sample interaction and that the commonly used instrumental response function needs to be replaced by a sample-dependent effective response function. We also show that, using the proper configurations in excitation and/or detection, it is possible to overcome the temporal smearing of the measured dynamics due to chirp-induced pulse broadening and recover the temporal resolution that would be afforded by the transform-limited pulses. We verify these predictions with experiments using broadband chirped pump and probe pulses. Our results allow optimization of the temporal resolution in the common case when the chirp of the pump and/or probe pulse is not corrected and may be extended to a broad range of time-resolved experiments.

  9. Effect of frequency chirp on supercontinuum generation in silicon waveguides with two zero-dispersion wavelengths

    NASA Astrophysics Data System (ADS)

    Cao, Yanmei; Zhang, Libin; Fei, Yonghao; Lei, Xun; Chen, Shaowu

    2015-01-01

    The influence of initial chirp on supercontinuum generation in SOI rib waveguide with two zero-dispersion wavelengths was studied numerically, based on the generalized nonlinear Schrödinger equation (GNSE). The full-width at half-maximum (FWHM) and the peak power of the pre-chirped hyperbolic secant in the simulation are 50 fs and 50 W, respectively. The simulation results indicate that a positive initial chirp makes the energy transfer to the normal dispersion zone by affecting self-phase modulation (SPM) and four-wave mixing (FWM) processes, and therefore enhances the supercontinuum bandwidth as well as improves the spectral flatness. In particular, at the optimal initial chirp parameter of C=3, the bandwidth at -10 dB level increases to about 1620 nm (from 1140 to 2760 nm), exceeding an octave-spanning.

  10. Practical design of optical diagnostics for chirped-pulse free-electron lasers

    Microsoft Academic Search

    Eric B. Szarmes; John M. J. Madey

    1992-01-01

    In recent years there have been several proposals to operate rf-linac-driven FELs with chirped electron and optical micropulses for use in fast time-resolved experiments. We have been actively pursuing this application on the Mark-III infrared FEL at Duke University, and have designed and procured an apparatus to achieve broad-band compression of chirped optical pulses between roughly 2.5 mum and 4.1

  11. Stretching and compressing of short laser pulses by chirped volume Bragg gratings: analytic and numerical modeling

    NASA Astrophysics Data System (ADS)

    Kaim, Sergiy; Mokhov, Sergiy; Zeldovich, Boris Y.; Glebov, Leonid B.

    2014-05-01

    The theory of stretching and compression of short light pulses by chirped volume Bragg gratings (CBGs) is reviewed based on spectral decomposition of short pulses and on wavelength-dependent coupled wave equations. Analytic theory of diffraction efficiency of CBG with constant chirp and approximate theory time-delay dispersion is presented. Comparison of approximate analytic results with exact numeric coupled-wave modeling shows excellent agreement for smooth heterogeneities of CBGs.

  12. Chirped pulse amplification of 300 fs pulses in an Alexandrite regenerative amplifier

    SciTech Connect

    Pessot, M.; Squier, J.; Bado, P.; Mourou, G. (Lab. for Laser Energetics, Univ. of Rochester, Rochester, NY (US)); Harter, D.J. (Allied Signal In., Corporate Technology, Morristown, NJ (US))

    1989-01-01

    The authors demonstrate the amplification of femtosecond dye laser pulses up to the 3.5 mJ level in an alexandrite regenerative amplifier. An expansion/compression system using diffraction gratings allows chirped pulse amplification techniques to be used to produce peak powers upwards of 1 GW. Limitations in the chirped pulse amplification of ultrashort pulses due to intracavity dispersive elements are discussed.

  13. Multiplexed Chirped Pulse Quantum Cascade Laser Measurements of Ammonia and Other Small Molecules

    NASA Astrophysics Data System (ADS)

    Picken, Craig; Langford, Nigel; Duxbury, Geoffrey

    2014-06-01

    Spectrometers based on Quantum Cascade (QC) lasers can be run in either continuous or pulsed operation. Although the instrumentation based upon the most recent versions of continuously operating QC lasers can have higher resolution than chirped lasers, using chirped pulse QC lasers can give an advantage when rapid changes in gas composition occur. For example, when jet engines are being tested, a variety of temperature dependent effects on the trace gas concentrations of the plume may be observed. Most pulsed QC lasers are operated in the down chirped mode, in which the chirp rate slows during the pulse. In our spectrometer the changes in frequency are recorded using two Ge etalons, one with a free spectral range of 0.0495 cm-1, and the other with a fringe spacing of 0.0195 cm-1.They can also be deployed in multiplex schemes in which two or more down-chirped lasers are used. In this paper we wish to show examples of the use of multiplexed chirped pulse lasers to allow overlapping spectra to be recorded. The examples of multiplex methods used are taken partly from measurements of 14NH3 and 15NH3 in the region from 1630 to 1622 cm-1, and partly from the use of other chirped pulse lasers operating in the 8 ?m region. Among the effects seen are rapid passage effects caused by the rapid down-chirp, and the use of gases such as nitrogen to cause variation in the shape of the collisional broadened absorption lines.

  14. 75 FR 1621 - Radio Broadcasting Services; AM or FM Proposals To Change the Community of License

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-12

    ...Station WALR-FM, Facility ID 48728, BPH-20091124ABA, From GREENVILLE, GA, To...FRANDSON, Station KZHK, Facility ID 40519, BPH-20090813ABE, From BUNKERVILLE, NV...Station WBBT- FM, Facility ID 31859, BPH-20091125ABI, From POWHATAN, VA,...

  15. 47 CFR 73.4154 - Network/AM, FM station affiliation agreements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Telecommunication 4 2011-10-01 2011-10-01 false Network/AM, FM station affiliation agreements. 73.4154 Section... Rules Applicable to All Broadcast Stations § 73.4154 Network/AM, FM station affiliation agreements. See...

  16. 47 CFR 73.4154 - Network/AM, FM station affiliation agreements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Telecommunication 4 2010-10-01 2010-10-01 false Network/AM, FM station affiliation agreements. 73.4154 Section... Rules Applicable to All Broadcast Stations § 73.4154 Network/AM, FM station affiliation agreements. See...

  17. Demonstration of high-fidelity dynamic optical arbitrary waveform generation.

    PubMed

    Fontaine, Nicolas K; Geisler, David J; Scott, Ryan P; He, Tingting; Heritage, Jonathan P; Yoo, S J B

    2010-10-25

    We experimentally demonstrate a dynamic line-by-line optical arbitrary waveform generation technique capable of generating continuous and bandwidth scalable high-fidelity waveforms without update rate limitations. Two quadrature modulators are used to create up to three spectral slices that are coherently combined by a passband-shaped multiplexer into a single contiguous spectrum to form complex optical waveforms with up to 30 GHz of bandwidth and 6 ns record lengths. PMID:21164638

  18. Detecting Subtle Differences in Behavior Using Waveform Display Analysis

    Microsoft Academic Search

    Keith M Campbell; Robert M Rohland; Michael J McGrath; Stephanie D Satoskar; Frank H Burton

    1998-01-01

    CAMPBELL, K. M., R. M. ROHLAND, M. J. McGRATH, S. D. SATOSKAR AND F. H. BURTON. Detecting subtle differences in behavior using waveform display analysis. Physiol Behav 64(1) 83–91, 1998. We have devised a method, behavioral waveform display analysis, to analyze complex ethological information by measuring behavior in real time and visualizing it as a time-dependent, multistate waveform. To facilitate

  19. Waveform Monitoring of Electric Discharge Machining by Wavelet Transform

    Microsoft Academic Search

    S. F. Yu; B. Y. Lee; W. S. Lin

    2001-01-01

    The waveform affects the quality and mechanical performance of a workpiece during electric discharge machining (EDM). This\\u000a study uses the wavelet transform to process the waveform of EDM. The data of the waveform are obtained from the voltage and\\u000a current between the workpiece and the electrode of the electric discharge machine, and are then calculated by the wavelet\\u000a transform. The

  20. Seismic waveform inversion using neural networks

    NASA Astrophysics Data System (ADS)

    De Wit, R. W.; Trampert, J.

    2012-12-01

    Full waveform tomography aims to extract all available information on Earth structure and seismic sources from seismograms. The strongly non-linear nature of this inverse problem is often addressed through simplifying assumptions for the physical theory or data selection, thus potentially neglecting valuable information. Furthermore, the assessment of the quality of the inferred model is often lacking. This calls for the development of methods that fully appreciate the non-linear nature of the inverse problem, whilst providing a quantification of the uncertainties in the final model. We propose to invert seismic waveforms in a fully non-linear way by using artificial neural networks. Neural networks can be viewed as powerful and flexible non-linear filters. They are very common in speech, handwriting and pattern recognition. Mixture Density Networks (MDN) allow us to obtain marginal posterior probability density functions (pdfs) of all model parameters, conditioned on the data. An MDN can approximate an arbitrary conditional pdf as a linear combination of Gaussian kernels. Seismograms serve as input, Earth structure parameters are the so-called targets and network training aims to learn the relationship between input and targets. The network is trained on a large synthetic data set, which we construct by drawing many random Earth models from a prior model pdf and solving the forward problem for each of these models, thus generating synthetic seismograms. As a first step, we aim to construct a 1D Earth model. Training sets are constructed using the Mineos package, which computes synthetic seismograms in a spherically symmetric non-rotating Earth by summing normal modes. We train a network on the body waveforms present in these seismograms. Once the network has been trained, it can be presented with new unseen input data, in our case the body waves in real seismograms. We thus obtain the posterior pdf which represents our final state of knowledge given the information in the training set and the real data.

  1. Resolution analysis in full waveform inversion

    NASA Astrophysics Data System (ADS)

    Fichtner, Andreas; Trampert, Jeannot

    2011-12-01

    We propose a new method for the quantitative resolution analysis in full seismic waveform inversion that overcomes the limitations of classical synthetic inversions while being computationally more efficient and applicable to any misfit measure. The method rests on (1) the local quadratic approximation of the misfit functional in the vicinity of an optimal earth model, (2) the parametrization of the Hessian in terms of a parent function and its successive derivatives and (3) the computation of the space-dependent parameters via Fourier transforms of the Hessian, calculated with the help of adjoint techniques. In the simplest case of a Gaussian approximation, we can infer rigorously defined 3-D distributions of direction-dependent resolution lengths and the image distortion introduced by the tomographic method. We illustrate these concepts with a realistic full waveform inversion for upper-mantle structure beneath Europe. As a corollary to the method for resolution analysis, we propose several improvements to full waveform inversion techniques. These include a pre-conditioner for optimization schemes of the conjugate-gradient type, a new family of Newton-like methods, an approach to adaptive parametrization independent from ray theory and a strategy for objective functional design that aims at maximizing resolution. The computational requirements of our approach are less than for a typical synthetic inversion, but yield a much more complete picture of resolution and trade-offs. While the examples presented in this paper are rather specific, the underlying idea is very general. It allows for problem-dependent variations of the theme and for adaptations to exploration scenarios and other wave-equation-based tomography techniques that employ, for instance, georadar or microwave data.

  2. Chirp rate is independent of male condition in a synchronising bushcricket.

    PubMed

    Hartbauer, M; Kratzer, S; Römer, H

    2006-03-01

    Males of the bushcricket Mecopoda elongata synchronise their chirps with neighbouring males, but because synchrony is imperfect, one male's chirp preceeds the other by some 50-200 ms. Since a male's intrinsic chirp rate is critical for the establishment of the leader role in a duet, and females prefer the leader in a choice situation, we investigated a possible condition dependence of this male trait. In a duet leader males are usually those calling at a higher intrinsic rate; therefore, we investigated whether calling at a higher rate indicates male condition. The calling metabolism was quantified in a respirometer; the factorial slope of males calling at a high rate was three times higher compared to males calling at lower rates. Males produce on average 3.4 singing bouts/per night, and there is a significant increase in chirp periods (CPs) with successive singing bouts. Call properties were investigated throughout a male's life; chirp period increases significantly with age. Two groups of males were reared on either a low- or a high-nutrition diet, and the influence of male condition on different song parameters was investigated. CPs in two feeding regimes did not differ significantly, although males of the low-nutrition diet group were significantly affected by nutrition with respect to mortality, a delayed last moult and reduced weight as adults. We therefore conclude that solo chirp rates do not reflect phenotypic male condition properly. PMID:16289569

  3. Recovering strain readings from chirping fiber Bragg gratings in composite overwrapped pressure vessels

    NASA Astrophysics Data System (ADS)

    Strutner, Scott M.; Pena, Frank; Piazza, Anthony; Parker, Allen R.; Richards, W. Lance; Carman, Gregory P.

    2014-04-01

    This study reports on signal recovery of optical fiber Bragg gratings embedded in a carbon fiber composite overwrapped pressure vessel's (COPV) structure which have become chirped due to microcracks. COPVs are commonly used for the storage of high pressure liquids and gases. They utilize a thin metal liner to seal in contents, with a composite overwrap to strengthen the vessel with minimal additional mass. A COPV was instrumented with an array of surface mounted and embedded fiber Bragg gratings (FBGs) for structural health monitoring (SHM) via strain sensing of the material. FBGs have been studied as strain sensors for the last couple decades. Many of the embedded FBGs reflected a multi-peak, chirped response which was not able to be interpreted well by the current monitoring algorithm. Literature and this study found that the chirping correlated with microcracks. As loading increases, so does the number of chirped FBGs and microcracks. This study uses optical frequency domain reflectometry (OFDR) to demultiplex the array of FBGs, and then sub- divide individual FBGs. When a FBG is sub-divided using OFDR, the gratings' strain along its length is recovered. The sub-divided chirped FBGs have strain gradients along their length from microcracks. Applying this to all chirped gratings, nearly the entirety of the embedded sensors' readings can be recovered into a series of single peak responses, which show very large local strains throughout the structure. This study reports on this success in recovering embedded FBGs signal, and the strain gradient from microcracks.

  4. Few-cycle optical waveform synthesis

    Microsoft Academic Search

    A. Poppe; R. Holzwarth; A. Apolonski; G. Tempea; Ch. Spielmann; T. W. Hänsch; F. Krausz

    2001-01-01

    .   We demonstrate cycle-slip-free electronic control of the carrier-envelope phase evolution of few-femtosecond light pulses,\\u000a optical access to its sub-cycle fluctuations and suppression of the amplitude noise of a mode-locked laser by phase control.\\u000a As a result, few-cycle light waveforms can now be synthesized with electric and magnetic fields reproducible to within a known\\u000a phase error (<0.3 rad) and an unprecedentedly

  5. Fundamental relationships inherent to lidar waveforms for classification

    NASA Astrophysics Data System (ADS)

    Neuenschwander, Amy; Magruder, Lori; Londo, Alexis; Tweddale, Scott

    2009-05-01

    Full-waveform laser altimetry has been used in the research community since the mid-1990s and this technology holds great potential for the science and defense communities. Laser waveforms are a digital recording of the entire temporal profile from the reflected laser energy. The shape of the returned laser waveform is a function of both laser and surface properties. Waveform metrics were extracted for each waveform and include peak amplitude, peak standard deviation, integrated canopy energy, integrated ground energy, total waveform energy, ratio between canopy and ground energy, rise time to the first peak, fall time of the last peak, and vegetation height. The utilization of such metrics provides a potential for discriminating and identifying discrete targets on a per-shot basis. Analysis of the entire reflected laser energy profile provides a detailed description of distributed targets/features along the laser line-of-sight. Waveform data collected over Camp Shelby, Mississippi reveal separation of conifer from broadleaf vegetation. Metrics such as integrated canopy energy and fall time were found to be higher in hardwood forest than pine forest. Other landscape features such as the presence of a burn are also detected with full-waveform data, which would otherwise be missed with discrete return elevation data. With new full-waveform systems entering the commercial sector, new possibilities emerge to utilize the lidar data to classify land cover as well as quantify surface parameters.

  6. Focal waveforms for various source waveforms driving a prolate-spheroidal impulse radiating antenna (IRA)

    NASA Astrophysics Data System (ADS)

    Altunc, Serhat; Baum, Carl E.; Christodoulou, Christos G.; Schamiloglu, Edl; Buchenauer, C. Jerald

    2008-08-01

    Impulse radiating antennas (IRAs) are designed to radiate very fast pulses in a narrow beam with low dispersion and high field amplitude. For this reason they have been used in a variety of applications. IRAs have been developed for use in the transient far-field region using parabolic reflectors. However, in this paper we focus in the near field region and develop the field waveform at the second focus of a prolate-spheroidal IRA. Certain skin cancers can be killed by the application of a high-amplitude electric field pulse. This can be accomplished by either inserting electrodes near the skin cancer or by applying fast, high-electric field pulses without direct contact. We investigate a new manifestation of an IRA, in which we use a prolate spheroid as a reflector instead of a parabolic reflector and focus in the near-field region instead of the far-field region. This technique minimizes skin damage associated with inserting electrodes near the tumor. Analytical and experimental behaviors for the focal waveforms of two and four-feed arm prolate-spheroidal IRAs are explored. With appropriate choice of the driving waveform we maximize the impulse field at the second focus. The focal waveform of a prolate-spheroidal IRA has been explained theoretically and verified experimentally.

  7. A combined waveform relaxation: waveform relaxation newton algorithm for efficient parallel circuit simulation

    Microsoft Academic Search

    Patrick Odent; Luc J. M. Claesen; Hugo De Man

    1990-01-01

    This paper presents two new techniques for accelerating circuit simulation. The first technique is an improvement of the parallel Waveform Relaxation Newton (WRN) method. The computations of all the timepoints are executed concurrently. Static task partitioning is shown to be an efficient method to limit the scheduling overhead. The second technique combines in a dynamic way the efficiency of the

  8. Pervasive post-Eocene faulting and folding in unconsolidated sediments of the Mississippi River, Central U.S. as imaged by high-resolution CHIRP seismic data

    NASA Astrophysics Data System (ADS)

    Fave, X. J.; Magnani, M.; Waldron, B. A.; McIntosh, K. D.; Saustrup, S.; Guo, L.

    2010-12-01

    Despite being located in the stable continental interior of the North American plate, in 1811-1812 the New Madrid Seismic Zone (NMSZ) experienced among the largest magnitude historical earthquakes that ever occurred in the U.S. Paleoseismological evidence shows that large earthquakes have been occurring every 500 yr in the region for the past few thousand years, and historical and instrumental seismicity demonstrate that the NMSZ fault system is actively deforming today. By contrast, motion rates emerging from almost twenty years of geodetic observations substantiate a very slow rate of deformation across the NMSZ faults, suggesting that present velocities are not representative of the long-term deformation rate of the NMSZ fault system, and that deformation has likely been accommodated along structures additional to the NMSZ. In the summer of 2010, a high-resolution marine seismic reflection survey was carried out along the Mississippi River as part of a multi-year cooperative effort to investigate the spatial and temporal distribution of deformation in the Mississippi Embayment. Coincident to the seismic reflection profile, the survey also acquired ~300 km of CHIRP (Edgetech SB-512i) data from Cape Girardeau, MO to Caruthersville, MO. The CHIRP used a 0.7-1.2 kHz source pulse and recorded to a depth of 5-50 m sub-bottom. Here we present the preliminary interpretation of part of the CHIRP profile along the Mississippi River north of Hickman, KY, where the survey imaged a highly reflective sedimentary package down to a depth of ~50 m. The sedimentary sequence is about 20 m thick and appears to be bounded at the top and at the bottom by angular unconformities. The package is mildly folded and pervasively faulted, in some cases by extensional faults that exhibit up to 2 m of displacement and that reach the riverbed. Based on exposure of Eocene deposits 7 km to the east of the study area, and on the correlation of electric and gamma logs of nearby oil, gas and water wells, projected from 12 km to the west and which penetrated the Eocene units at a depth of 67 m, we determined that the reflective package corresponds to one of the elements of the Jackson Fm, (i.e. the top of the Eocene and of the Tertiary sequences), sealed at the top by the basal unconformity of the Mississippi River Quaternary alluvium and at the bottom by the Claiborne Group deposits. ¬

  9. Resonant tunneling and the bimodal symmetric fission of sup 258 Fm

    SciTech Connect

    Bhandari, B.S. (Department of Physics, Faculty of Science, University of Garyounis, Benghazi, Libya (LY))

    1991-02-25

    The concept of resonant tunneling is invoked to explain the sharp drop in the measured spontaneous-fission half-life when going from {sup 256}Fm to {sup 258}Fm. Various consequences of such a suggestion on the other observed characteristics of the bimodal symmetric fission of {sup 258}Fm are briefly discussed.

  10. Design of Wearable Multi-resonance Folded Dipole Antenna for FM Reception Using Conductive Textile

    E-print Network

    Nam, Sangwook

    Design of Wearable Multi-resonance Folded Dipole Antenna for FM Reception Using Conductive Textile used Metal Composite embroidery Yarns (MECYs) for FM reception antenna. If the antenna is designed, the FM antenna needs to maintain approximately 87 ~ 130MHz wide bandwidth for a marginal design, although

  11. 75 FR 9530 - FM TABLE OF ALLOTMENTS, French Lick, Indiana, and Irvington, Kentucky.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-03

    ...RM-11412] FM TABLE OF ALLOTMENTS, French Lick, Indiana, and Irvington, Kentucky...modifies the license of Station WFLQ(FM), French Lick, Indiana, to specify operation...the licensee of Station WFLQ(FM), French Lick, Indiana, to show cause why...

  12. Who Does What? Office for Research Safety (ORS), Facilities Management (FM), Risk Management (RM), University Police

    E-print Network

    Shull, Kenneth R.

    ) How can I get my emergency shower tested? FM Emergency shower testing involves turning on the shower are also connected to alarms that notify FM when they are in use. How can I get my a faucet or deck.) How can I get my chemical fume hood fixed if it has a DO NOT USE sign on it? FM When Salus

  13. Automatic Calibration of Modified FM Synthesis to Harmonic Sounds using Genetic Algorithms

    E-print Network

    Smyth, Tamara

    Automatic Calibration of Modified FM Synthesis to Harmonic Sounds using Genetic Algorithms Matthieu scheme. Genetic algorithms (GA) have been used rather exten- sively for this purpose, and in particular to further explore its modified counterpart, Modified FM (ModFM), which has not been used as widely, and its

  14. AM and high-harmonic FM laser mode locking

    Microsoft Academic Search

    Ryan P. Scott; Corey V. Bennett; Brian H. Kolner

    1997-01-01

    We demonstrate a new technique of active mode locking that combines amplitude-modulated ~AM! mode locking at the cavity fundamental repetition rate with frequency-modulated ~FM! mode locking at a high harmonic. This method combines the advantages of pulse shortening by high-harmonic mode locking while preserving the higher peak powers available at the fundamental repetition rate. We demonstrate this technique using a

  15. fishmeal (FM) (121 kg FM and 74 kg barley grain/t), whereas in the goat trial, FM mixture (FG) was composed (kg/t) of 769 barley grain, 112 SBM, 50 FM, the other ingredients remaining the

    E-print Network

    Paris-Sud XI, Université de

    digesta and NRNA/totalN ratio of bacteria isolated by differential centrifugation of duodenal content no difference between treatments in ewe milk fat (C 44 vs FE 43 g/kg) or protein content (C 54 vs FE 53 g fed FM produced milk with a higher fat (C 32 vs FG 36 g/kg) and protein (C 38 vs FG 41 g/kg) content

  16. Analytical Approaches to Guide SLS Fault Management (FM) Development

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    2012-01-01

    Extensive analysis is needed to determine the right set of FM capabilities to provide the most coverage without significantly increasing the cost, reliability (FP/FN), and complexity of the overall vehicle systems. Strong collaboration with the stakeholders is required to support the determination of the best triggers and response options. The SLS Fault Management process has been documented in the Space Launch System Program (SLSP) Fault Management Plan (SLS-PLAN-085).

  17. The Marriage of Spectroscopy and Dynamics: Chirped-Pulse Fourier-Transform Mm-Wave Cp-Ft Spectroscopy in Pulsed Uniform Supersonic Flows

    NASA Astrophysics Data System (ADS)

    Abeysekera, Chamara; Oldham, James M.; Suits, Arthur G.; Park, G. Barratt; Field, Robert W.

    2012-06-01

    A new experimental scheme is presented that combines two powerful emerging technologies: chirped-pulse Fourier-transform mm-Wave spectroscopy and pulsed uniform supersonic flows. It promises a nearly universal detection method that can deliver quantitative isomer, conformer, and vibrational level specific detection, characterization of unstable reaction products and intermediates, and perform unique spectroscopic, kinetics, and dynamics measurements. Chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy, pioneered by Pate and coworkers, allows rapid acquisition of broadband microwave spectrum through advancements in waveform generation and oscilloscope technology. This revolutionary approach has successfully been adapted to higher frequencies by the Field group at MIT. Our new apparatus will exploit amplified chirped pulses in the range of 26-40 GHz, in combination with a pulsed uniform supersonic flow from a Laval nozzle. This nozzle source, pioneered by Rowe, Sims, and Smith for low temperature kinetics studies, produces thermalized reactants at high densities and low temperatures perfectly suitable for reaction dynamics experiments studied using the CP-mmW approach. This combination of techniques shall enhance the thousand-fold improvement in data acquisition rate achieved in the CP method by a further 2-3 orders of magnitude. A pulsed flow alleviates the challenges of continuous uniform flow, e.g. large gas loads and reactant consumption rates. In contrast to other pulsed Laval systems currently in use, we will use a fast piezo valve and small chambers to achieve the desired pressures while minimizing the gas load, so that a 10 Hz repetition rate can be achieved with one turbomolecular pump. The proposed technique will be suitable for many diverse fields, including fundamental studies in spectroscopy and reaction dynamics, reaction kinetics, combustion, atmospheric chemistry, and astrochemistry. We expect a significant advancement in the ability to detect absolute populations of complex reaction products under near-nascent conditions, providing the powerful method of reaction dynamics with a universal spectroscopic probe capable of capturing the details of complex chemistry for specific product isomers and conformers.

  18. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

    SciTech Connect

    Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

    2007-12-10

    We conduct a detailed test of a recently developed technique, CAPloc, in recovering source parameters from a few stations against results from a large broadband network. The method uses a library of 1D Green’s functions which are broken into segments and matched to waveform observations with adjustable timing shifts. These shifts can be established by calibration against a distribution of well-located earthquake and assembled in tomographic images for predicting various phase-delays. Synthetics generated from 2D cross-sections through these models indicates that 1D synthetic waveforms are sufficient in modeling but simply shifted in time for hard-rock sites. This simplification allows the source inversion for both mechanism and location to be easily obtained by grid search. We test one-station mechanisms for 160 events against the array for both PAS and GSC which have data since 1960. While one station solutions work well (about 90%), joint solutions produce more reliable and defensible results. Inverting for both mechanism and location also works well except for certain difficult paths that cross deep basins or propagate along mountain ridges.

  19. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

    SciTech Connect

    Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

    2009-01-27

    Abstract We conduct a detailed test of a recently developed technique, CAPloc, in recovering source parameters from a few stations against results from a large broadband network in Southern California. The method uses a library of 1D Green’s functions which are broken into segments and matched to waveform observations with adjustable timing shifts. These shifts can be established by calibration against a distribution of well-located earthquakes and assembled in tomographic images for predicting various phase-delays. Synthetics generated from 2D cross-sections through these models indicates that 1D synthetic waveforms are sufficient in modeling but simply shifted in time for most hard-rock sites. This simplification allows the source inversion for both mechanism and location to easily obtain by grid search. We test one-station mechanisms for 160 events against the array for both PAS and GSC which have data since 1960. While individual solutions work well (about 90%), joint solutions produce more reliable and defensible results. Inverting for both mechanism and location also works well except for certain complex paths across deep basins and along mountain ridges.

  20. Target discrimination technique utilizing noise waveforms

    NASA Astrophysics Data System (ADS)

    Woodington, Gordon; DeLuca, Mark; Moro, Richard; Lemus, Daniel; Vela, Russell; Narayanan, Ram

    2011-06-01

    Noise waveforms generated using low cost diodes are a simple way for radars to transmit a wideband (> 4 GHz) multi-bit pseudorandom code for use in a cross correlation receiver. This type of waveform also has the advantage of being difficult to intercept and is less prone to interfere with adjacent systems. Radar designed to operate over this wide frequency range can take advantage of unique target Radar Cross Section (RCS) ripple versus frequency for objects of different materials and sizes. Specifically the periodicity and amplitude of the ripple is dependent on the shape and size of a target. Since background clutter does not display this variation, RCS variation determines whether a known target is present in a return. This paper will present the radar hardware and signal processing techniques used to maximize a target's unique spectral response against a cluttered background. The system operates CW over a 4-8 GHz bandwidth requiring the need to address issues regarding range resolution and far out undesired returns. Lessons learned from field observations and mitigation techniques incorporated in the system are included. This paper also deals with the signal processing technique used for detection, then discrimination. Detection thresholds are set and triggered by a simple correlation peak level. Discrimination involves inspection of the spectral return. A comparison performed in real time to a stored library value determines the presence of known objects. Measured data provided demonstrates the ability of the radar to discriminate multiple targets against multiple backgrounds.

  1. Propagation effects on a monocycle waveform

    NASA Astrophysics Data System (ADS)

    Saffold, James A.; Engler, Harold F.

    1993-05-01

    It is well documented that multipath interference at low grazing angles is an issue for detection and tracking. As the conventional systems, a propagation factor is derived which quantifies system loss due to amplitude fading and phase distortion caused by the interference of 'free space' signals with multipath. For an ultrawide bandwidth (UWB) monocycle waveform operating at UHF, the earth's surface generally appears smooth and supports dominant coherent (specular) reflection. For interference patterns dominated by specular multipath, a closed form of the gain/loss (G) expected at the output of a matched filter (used as the UWB radar's receiver model) was derived and evaluated for a frequency dispersive and non- dispersive terrain model. The frequency dependence of the gain/loss function and the relative weighting of the multipath fields for the scenario analyzed was found to be dominated by the line spectrum of the UWB waveform S(f). In addition, for multipath to have any significant effect in a single monocycle's period, the propagation delay or time- difference-on-arrival (TDOA) of the single bounce and double bounce multipath interference terms must satisfy time coincidence criteria. The propagation factor (PFuwb) derived in this paper averages the range and frequency variations of the derived gain/loss function G(f,R) into a single value which can be used as input to a UWB system loss factor for short range air defense (SRAD) scenarios.

  2. Fast prediction and evaluation of gravitational waveforms using surrogate models

    E-print Network

    Scott E. Field; Chad R. Galley; Jan S. Hesthaven; Jason Kaye; Manuel Tiglio

    2014-02-28

    [Abridged] We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and in more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced-order model that can be used as a surrogate for the true/fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order m L + m c_f online operations where c_f denotes the fitting function operation count and, typically, m << L. We generate accurate surrogate models for Effective One Body (EOB) waveforms of non-spinning binary black hole coalescences with durations as long as 10^5 M, mass ratios from 1 to 10, and for multiple harmonic modes. We find that these surrogates are three orders of magnitude faster to evaluate as compared to the cost of generating EOB waveforms in standard ways. Surrogate model building for other waveform models follow the same steps and have the same low online scaling cost. For expensive numerical simulations of binary black hole coalescences we thus anticipate large speedups in generating new waveforms with a surrogate. As waveform generation is one of the dominant costs in parameter estimation algorithms and parameter space exploration, surrogate models offer a new and practical way to dramatically accelerate such studies without impacting accuracy.

  3. A Study of Mexican Free-Tailed Bat Chirp Syllables: Bayesian Functional Mixed Models for Nonstationary Acoustic Time Series

    PubMed Central

    MARTINEZ, Josue G.; BOHN, Kirsten M.; CARROLL, Raymond J.

    2013-01-01

    We describe a new approach to analyze chirp syllables of free-tailed bats from two regions of Texas in which they are predominant: Austin and College Station. Our goal is to characterize any systematic regional differences in the mating chirps and assess whether individual bats have signature chirps. The data are analyzed by modeling spectrograms of the chirps as responses in a Bayesian functional mixed model. Given the variable chirp lengths, we compute the spectrograms on a relative time scale interpretable as the relative chirp position, using a variable window overlap based on chirp length. We use 2D wavelet transforms to capture correlation within the spectrogram in our modeling and obtain adaptive regularization of the estimates and inference for the regions-specific spectrograms. Our model includes random effect spectrograms at the bat level to account for correlation among chirps from the same bat, and to assess relative variability in chirp spectrograms within and between bats. The modeling of spectrograms using functional mixed models is a general approach for the analysis of replicated nonstationary time series, such as our acoustical signals, to relate aspects of the signals to various predictors, while accounting for between-signal structure. This can be done on raw spectrograms when all signals are of the same length, and can be done using spectrograms defined on a relative time scale for signals of variable length in settings where the idea of defining correspondence across signals based on relative position is sensible. PMID:23997376

  4. A Study of Mexican Free-Tailed Bat Chirp Syllables: Bayesian Functional Mixed Models for Nonstationary Acoustic Time Series.

    PubMed

    Martinez, Josue G; Bohn, Kirsten M; Carroll, Raymond J; Morris, Jeffrey S

    2013-06-01

    We describe a new approach to analyze chirp syllables of free-tailed bats from two regions of Texas in which they are predominant: Austin and College Station. Our goal is to characterize any systematic regional differences in the mating chirps and assess whether individual bats have signature chirps. The data are analyzed by modeling spectrograms of the chirps as responses in a Bayesian functional mixed model. Given the variable chirp lengths, we compute the spectrograms on a relative time scale interpretable as the relative chirp position, using a variable window overlap based on chirp length. We use 2D wavelet transforms to capture correlation within the spectrogram in our modeling and obtain adaptive regularization of the estimates and inference for the regions-specific spectrograms. Our model includes random effect spectrograms at the bat level to account for correlation among chirps from the same bat, and to assess relative variability in chirp spectrograms within and between bats. The modeling of spectrograms using functional mixed models is a general approach for the analysis of replicated nonstationary time series, such as our acoustical signals, to relate aspects of the signals to various predictors, while accounting for between-signal structure. This can be done on raw spectrograms when all signals are of the same length, and can be done using spectrograms defined on a relative time scale for signals of variable length in settings where the idea of defining correspondence across signals based on relative position is sensible. PMID:23997376

  5. Chromatin isolation by RNA purification (ChIRP).

    PubMed

    Chu, Ci; Quinn, Jeffrey; Chang, Howard Y

    2012-01-01

    Long noncoding RNAs are key regulators of chromatin states for important biological processes such as dosage compensation, imprinting, and developmental gene expression (1,2,3,4,5,6,7). The recent discovery of thousands of lncRNAs in association with specific chromatin modification complexes, such as Polycomb Repressive Complex 2 (PRC2) that mediates histone H3 lysine 27 trimethylation (H3K27me3), suggests broad roles for numerous lncRNAs in managing chromatin states in a gene-specific fashion (8,9). While some lncRNAs are thought to work in cis on neighboring genes, other lncRNAs work in trans to regulate distantly located genes. For instance, Drosophila lncRNAs roX1 and roX2 bind numerous regions on the X chromosome of male cells, and are critical for dosage compensation (10,11). However, the exact locations of their binding sites are not known at high resolution. Similarly, human lncRNA HOTAIR can affect PRC2 occupancy on hundreds of genes genome-wide( 3,12,13), but how specificity is achieved is unclear. LncRNAs can also serve as modular scaffolds to recruit the assembly of multiple protein complexes. The classic trans-acting RNA scaffold is the TERC RNA that serves as the template and scaffold for the telomerase complex (14); HOTAIR can also serve as a scaffold for PRC2 and a H3K4 demethylase complex (13). Prior studies mapping RNA occupancy at chromatin have revealed substantial insights (15,16), but only at a single gene locus at a time. The occupancy sites of most lncRNAs are not known, and the roles of lncRNAs in chromatin regulation have been mostly inferred from the indirect effects of lncRNA perturbation. Just as chromatin immunoprecipitation followed by microarray or deep sequencing (ChIP-chip or ChIP-seq, respectively) has greatly improved our understanding of protein-DNA interactions on a genomic scale, here we illustrate a recently published strategy to map long RNA occupancy genome-wide at high resolution (17). This method, Chromatin Isolation by RNA Purification (ChIRP) (Figure 1), is based on affinity capture of target lncRNA:chromatin complex by tiling antisense-oligos, which then generates a map of genomic binding sites at a resolution of several hundred bases with high sensitivity and low background. ChIRP is applicable to many lncRNAs because the design of affinity-probes is straightforward given the RNA sequence and requires no knowledge of the RNA's structure or functional domains. PMID:22472705

  6. Coupled Waveform Analysis in Dynamic Characterization of Lossy Solids

    E-print Network

    Guzina, Bojan

    Coupled Waveform Analysis in Dynamic Characterization of Lossy Solids Bojan B. Guzina, M.ASCE,1-infinite solid, a rational analytical and computational framework is developed for nonintrusive, wave; Damping; Viscoelasticity; Solids. Introduction Inverse analysis of the waveforms stemming from a surficial

  7. Method and apparatus for resonant frequency waveform modulation

    DOEpatents

    Taubman, Matthew S [Richland, WA

    2011-06-07

    A resonant modulator device and process are described that provide enhanced resonant frequency waveforms to electrical devices including, e.g., laser devices. Faster, larger, and more complex modulation waveforms are obtained than can be obtained by use of conventional current controllers alone.

  8. Gravitational waveforms from the evaporating ACO cosmic string loop

    NASA Astrophysics Data System (ADS)

    Anderson, Malcolm

    2009-04-01

    The linearly polarized gravitational waveforms from a certain type of rotating, evaporating cosmic string—the Allen-Casper-Ottewill loop—are constructed and plotted over the lifetime of the loop. The formulae for the waveforms are simple and exact, and describe waves which attenuate self-similarly, with the amplitude and period of the waves falling off linearly with time.

  9. Wideband Waveform Optimization with Energy Detector Receiver in Cognitive Radio

    E-print Network

    Qiu, Robert Caiming

    Wideband Waveform Optimization with Energy Detector Receiver in Cognitive Radio Zhen Hu Department investigates the transmitted waveform optimization issues for wideband cognitive radio with energy detector receiver. The motivation is to provide a cheap cognitive radio network with simple and cheap cognitive

  10. Cognitive radio - an adaptive waveform with spectral sharing capability

    Microsoft Academic Search

    Vasu D. Chakravarthy; A. K. Shaw; Michael A. Temple; James P. Stephens

    2005-01-01

    The growth of wireless applications and spectral limitations are serious concerns for both the military and civilian communities. Cognitive radio (CR) technologies expand spectrum efficiency using elements of space, time and frequency diversity that up to now have not been exploited. An adaptive waveform (AW) generation technique is presented which adapts to the changing electromagnetic environment and synthesizes waveform features

  11. Multigrid Waveform Relaxation for Anisotropic Partial Di erential Equations

    E-print Network

    elliptic case to waveform relaxation methods for the time- dependent parabolic case. We study line. In the sta- tionary case standard multigrid waveform relaxation methods brake down when applied relaxation methods. Line relaxa- tion, semicoarsening and multiple semicoarsening are proposed as methods

  12. An optimal design method for magnetic resonance imaging gradient waveforms.

    PubMed

    Simonetti, O P; Duerk, J L; Chankong, V

    1993-01-01

    A method of using nonlinear constrained optimization to design gradient waveforms for magnetic resonance imaging is described. Formulation and solution of the waveform optimization problem are described and example waveforms are presented for a variety of design objectives and constraint sets. Most design objectives can be expressed as linear or quadratic functions of the discrete parameter set, and most constraint functions are linear. Thus, linear and quadratic programming techniques can be utilized to solve the optimization problem. Among the objectives considered are: minimize RMS current; minimize waveform slewing; minimize waveform moments to reduce motion induced dephasing; minimize echo time (TE) for given imaging and motion refocusing conditions; maximize the gradient amplitude during RF application and sampling and the area of the phase encoding waveform to maximize resolution; and minimize or maximize the gradient b factor or diffusion sensitivity. This optimal design procedure produces physically realizable waveforms which optimally achieve specific imaging and motion artifact reduction goals, and it is likely to reduce waveform design time by making it more scientifically (rather than heuristically) based. PMID:18218425

  13. Noncooperative waveform adaptation games in multiuser wireless communications

    Microsoft Academic Search

    Stefano Buzzi; H. Vincent Poor; Daniela Saturnino

    2009-01-01

    This article provided a survey of waveform adaptation algorithms for multiuser wireless communications based on noncooperative game theory. Emphasis has been given to the problem of spreading code optimization in CDMA systems, a research topic that has attracted the interest of many researchers for years, and some space has also been devoted to other applications of waveform adaptation algorithms, such

  14. Back-side-coated chirped mirrors with ultra-smooth broadband dispersion characteristics

    NASA Astrophysics Data System (ADS)

    Matuschek, N.; Gallmann, L.; Sutter, D. H.; Steinmeyer, G.; Keller, U.

    We demonstrate a new technique for the design of chirped mirrors with extremely smooth dispersion characteristics over an extended ultra-broadband wavelength range. Our approach suppresses spectral dispersion oscillations, which can lead to unwanted strong spectral modulations and limit the bandwidth of mode-locked laser pulses. Dispersion oscillations are significantly reduced by coating the chirped mirror structure on the back side of a substrate, providing ideal impedance matching between coating and ambient medium. An anti-reflection coating may be added on the front side of the substrate, geometrically separated from the chirped mirror. The chirped mirror structure and the anti-reflection coating are non-interfering and can be independently designed and optimized. The separation of both coating sections provides a much better solution for the impedance-matching problems than previous approaches to chirped mirror design. We show by a theoretical analysis and numerical simulations that minimum dispersion oscillations are achieved if the index of the substrate is identical to the index of one of the coating materials and if double-chirping is used for the chirped mirror structure. Based on this analysis, we design a mirror that supports a bandwidth of 220 THz with group delay dispersion oscillations of about 2 fs2 (rms), an order-of magnitude improvement compared to previous designs of similar bandwidth. In a first experimental demonstration of back-side-coated (BASIC) mirrors, we achieve nearly transform-limited and virtually unchirped pulses of 5.8 fs duration from a Kerr-lens mode-locked Ti:sapphire laser. BASIC mirrors are particularly suited for higher-order dispersion compensation schemes. They support the extremely broad spectra of few-cycle pulses and promise to provide clean pulse shapes in this regime.

  15. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

    SciTech Connect

    Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

    2008-10-17

    This quarter, we have focused on several tasks: (1) Building a high-quality catalog of earthquake source parameters for the Middle East and East Asia. In East Asia, we computed source parameters using the CAP method for a set of events studied by Herrman et al., (MRR, 2006) using a complete waveform technique. Results indicated excellent agreement with the moment magnitudes in the range 3.5 -5.5. Below magnitude 3.5 the scatter increases. For events with more than 2-3 observations at different azimuths, we found good agreement of focal mechanisms. Depths were generally consistent, although differences of up to 10 km were found. These results suggest that CAP modeling provides estimates of source parameters at least as reliable as complete waveform modeling techniques. However, East Asia and the Yellow Sea Korean Paraplatform (YSKP) region studied are relatively laterally homogeneous and may not benefit from the CAP method’s flexibility to shift waveform segments to account for path-dependent model errors. A more challenging region to study is the Middle East where strong variations in sedimentary basin, crustal thickness and crustal and mantle seismic velocities greatly impact regional wave propagation. We applied the CAP method to a set of events in and around Iran and found good agreement between estimated focal mechanisms and those reported by the Global Centroid Moment Tensor (CMT) catalog. We found a possible bias in the moment magnitudes that may be due to the thick low-velocity crust in the Iranian Plateau. (2) Testing Methods on a Lifetime Regional Data Set. In particular, the recent 2/21/08 Nevada Event and Aftershock Sequence occurred in the middle of USArray, producing over a thousand records per event. The tectonic setting is quite similar to Central Iran and thus provides an excellent testbed for CAP+ at ranges out to 10°, including extensive observations of crustal thinning and thickening and various Pnl complexities. Broadband modeling in 1D, 2D, and 3D will be presented. (3) Shallow Crustal Structure and Sparse Network Source Inversions for Southern California. We conducted a detailed test of a recently developed technique, CAPloc, in recovering source parameters including location and depth based on tomographic maps. We tested two-station solutions against 160 well determined events which worked well except for paths crossing deep basins and along mountain ridges.

  16. Single shot amplitude and phase characterization of optical arbitrary waveforms.

    PubMed

    Supradeepa, V R; Leaird, Daniel E; Weiner, Andrew M

    2009-08-01

    Using a time-gated dual quadrature spectral interferometry technique, for the first time we demonstrate single-shot characterization of both spectral amplitude and phase of approximately 1THz bandwidth optical arbitrary waveforms generated from a 10 GHz frequency comb. Our measurements provide a temporal resolution of 1ps over a record length of 100ps. Singleshot characterization becomes particularly relevant when waveform synthesis operations are updated at the repetition rate of the comb allowing creation of potentially infinite record length waveforms. We first demonstrate unambiguous single shot retrieval using rapidly updating waveforms. We then perform additional single-shot measurements of static user-defined waveforms generated via line-by-line pulse shaping. PMID:19654851

  17. Frequency-domain direct waveform inversion based on perturbation theory

    NASA Astrophysics Data System (ADS)

    Kwak, Sangmin; Kim, Youngseo; Shin, Changsoo

    2014-05-01

    A direct waveform inversion based on perturbation theory is proposed to delineate a subsurface velocity structure from seismic data. This technique can directly compute the difference between the actual subsurface velocity and an initial guess of the velocity, while full waveform inversion updates the velocity model in the directions of reducing the data residual. Unlike full waveform inversion using the steepest descent method, the direct waveform inversion does not require a proper step length to iteratively update the velocity model. We present an algorithm for the waveform inversion method in the frequency domain and numerical examples demonstrating how the inversion method can reconstruct subsurface velocity structures using surface seismic data. The time-domain seismograms synthesized in the inversion procedure match the corresponding shot-gather seismograms of field data.

  18. Wavelet analysis of electric adjustable speed drive waveforms

    SciTech Connect

    Czarkowski, D. [Polytechnic Univ., Brooklyn, NY (United States). Dept. of Electrical Engineering; Domijan, A. Jr. [Univ. of Florida, Gainesville, FL (United States). Dept. of Electrical and Computer Engineering

    1998-10-01

    The three most common adjustable speed drives (ASDs) used in HVAC equipment, namely, pulse-width modulated (PWM) induction drive, brushless-dc drive, and switched-reluctance drive, generate non-periodic and nonstationary electric waveforms with sharp edges and transients. Deficiencies of Fourier transform methods in analysis of such ASD waveforms prompted an application of the wavelet transform. Results of discrete wavelet transform (DWT) analysis of PWM inverter-fed motor waveforms are presented. The best mother wavelet for analysis of the recorded waveforms is selected. Data compression properties of the selected mother wavelet are compared to those of the fast Fourier transform (FFT). Multilevel feature detection of ASD waveforms using the DWT is shown.

  19. Mismatch characteristics of optical parametric chirped pulse amplification

    NASA Astrophysics Data System (ADS)

    Novák, O.; Tur?i?ová, H.; Divoký, M.; Huynh, J.; Straka, P.

    2014-02-01

    The stability of an optical parametric chirped pulse amplifier (OPCPA) is influenced by time and the angular matching of the input beams. We derived the Gaussian dependence of the monochromatic signal gain on the small mismatch between the signal and pump beams. Gain characteristics were also calculated for polychromatic amplification and the impact of different beam mismatches and interaction geometries was explained. The asymmetry of the energy gain, and the square root dependence of the phase matched wavelength on beam angles were found. The predicted dependences were verified in a noncollinear OPCPA system with LBO and KDP crystal amplifying pulses of a Ti:sapphire laser around a central wavelength of 800 nm, pumped by the third harmonic frequency of an iodine gas laser at a wavelength of 438 nm. The widths of the gain curves in the dependence on both the pump–signal or the phase matching angles varied from several tenths to a few milliradians. The gain curve widths dependent on the pump–signal pulse delay were about two thirds of the pump pulse width for moderate pumping and about a half of the pump pulse width for pumping on the order of GW cm?2. A stable gain output is achieved if angular and temporal fluctuations are fractions of the measured gain curve widths, and when the signal direction is between the pump and the crystal principal axis (i.e. in the psz geometry).

  20. Binary black hole merger dynamics and waveforms

    NASA Technical Reports Server (NTRS)

    Baker, John G.; Centrella, Joan; Choi, Dae-II; Koppitz, Michael; vanMeter, James

    2006-01-01

    We apply recently developed techniques for simulations of moving black holes to study dynamics and radiation generation in the last few orbits and merger of a binary black hole system. Our analysis produces a consistent picture from the gravitational wave forms and dynamical black hole trajectories for a set of simulations with black holes beginning on circular-orbit trajectories at a variety of initial separations. We find profound agreement at the level of 1% among the simulations for the last orbit, merger and ringdown, resulting in a final black hole with spin parameter a/m = 0.69. Consequently, we are confident that this part of our waveform result accurately represents the predictions from Einstein's General Relativity for the final burst of gravitational radiation resulting from the merger of an astrophysical system of equal-mass non-spinning black holes. We also find good agreement at a level of roughly 10% for the radiation generated in the preceding few orbits.

  1. Waveform Synthesizer For Imaging And Ranging Applications

    DOEpatents

    Dubbert, Dale F. (Cedar Crest, NM); Dudley, Peter A. (Albuquerque, NM); Doerry, Armin W. (Albuquerque, NM); Tise, Bertice L. (Albuquerque, NM)

    2004-12-28

    Frequency dependent corrections are provided for Local Oscillator (LO) feed-through. An operational procedure filters LO feed-through effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver, unwanted energies, such as LO feed-through energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of LO feed-through can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

  2. Waveform Selectivity at the Same Frequency

    E-print Network

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F

    2014-01-01

    Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of the circuit elements are then combined to absorb or tran...

  3. Waveform Synthesizer For Imaging And Ranging Applications

    DOEpatents

    DUDLEY, PETER A.; [et al

    2004-11-30

    Frequency dependent corrections are provided for quadrature imbalance. An operational procedure filters imbalance effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver; unwanted energies, such as imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of quadrature imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

  4. DIODE LASER MEASUREMENTS OF HF CONCENTRATIONS PRODUCED FROM HEPTANE/AIR PAN FIRES EXTINGUISHED BY FE-36, FM-200, FE-36 PLUS APP, AND FM-200 PLUS APP

    EPA Science Inventory

    Tunable diode laser absorption spectroscopy (TDLAS) is used to measure the time evolution of hydrogen fluoride (HF) concentrations produced from a series of enclosed heptane/air pan fires extinguished by FE-36, FM-200, FE-35 plus ammonium polyphosphate (APP), or FM-200 plus APP. ...

  5. Characteristics of nonlinear imaging of broadband laser stacked by chirped pulses

    NASA Astrophysics Data System (ADS)

    Wang, Youwen; You, Kaiming; Chen, Liezun; Lu, Shizhuan; Dai, Zhiping; Ling, Xiaohui

    2014-11-01

    Nanosecond-level pulses of specific shape is usually generated by stacking chirped pulses for high-power inertial confinement fusion driver, in which nonlinear imaging of scatterers may damage precious optical elements. We present a numerical study of the characteristics of nonlinear imaging of scatterers in broadband laser stacked by chirped pulses to disclose the dependence of location and intensity of images on the parameters of the stacked pulse. It is shown that, for sub-nanosecond long sub-pulses with chirp or transform-limited sub-pulses, the time-mean intensity and location of images through normally dispersive and anomalously dispersive self-focusing medium slab are almost identical; While for picosecond-level short sub-pulses with chirp, the time-mean intensity of images for weak normal dispersion is slightly higher than that for weak anomalous dispersion through a thin nonlinear slab; the result is opposite to that for strong dispersion in a thick nonlinear slab; Furthermore, for given time delay between neighboring sub-pulses, the time-mean intensity of images varies periodically with chirp of the sub-pulse increasing; for a given pulse width of sub-pulse, the time-mean intensity of images decreases with the time delay between neighboring sub-pulses increasing; additionally, there is a little difference in the time-mean intensity of images of the laser stacked by different numbers of sub-pulses. Finally, the obtained results are also given physical explanations.

  6. Stimulated Brillouin scattering suppression with a chirped laser seed: comparison of dynamical model to experimental data

    NASA Astrophysics Data System (ADS)

    Petersen, Eliot; Yang, Zhi; White, Jeffrey O.; Rakuljic, George; Satyan, Naresh; Vasilyev, Arseny; Yariv, Amnon

    2014-03-01

    When scaling CW single-mode fiber amplifiers to high power, the first nonlinear limitation that appears for narrowlinewidth seed lasers is stimulated Brillouin scattering (SBS). We present a dynamical simulation of Brillouin scattering in a Yb-doped fiber amplifier that numerically solves the differential equations in z and t describing the laser, Stokes and pump waves, the inversion, and the density fluctuations that seed the scattering process. We compare the model to experimental data, and show that a linearly chirped seed laser is an efficient form of SBS suppression; especially for long delivery fibers. The frequency chirp decreases the interaction length by chirping through the Brillouin resonance in a time that is short compared to the fiber transit time. The seed has a highly linear chirp of 1014 - 1016 Hz/s at 1064 nm which preserves a well-defined phase relationship in time. This method of SBS suppression retains a long effective coherence length for purposes of coherent combining, while at high chirps appears to the SBS as a large linewidth, increasing the threshold. An increase in fiber length increases the laser bandwidth as seen by the SBS, leading to a fiberlength- independent SBS threshold.

  7. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models

    NASA Astrophysics Data System (ADS)

    Field, Scott E.; Galley, Chad R.; Hesthaven, Jan S.; Kaye, Jason; Tiglio, Manuel

    2014-07-01

    We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mcfit) online operations, where cfit denotes the fitting function operation count and, typically, m ?L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 105M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in generating new waveforms with a surrogate. As waveform generation is one of the dominant costs in parameter estimation algorithms and parameter space exploration, surrogate models offer a new and practical way to dramatically accelerate such studies without impacting accuracy. Surrogates built in this paper, as well as others, are available from GWSurrogate, a publicly available python package.

  8. Multi channel FM reflection profiler for buried pipeline surveying

    SciTech Connect

    Schock, S.G.; LeBlanc, L.R. [Florida Atlantic Univ., Boca Raton, FL (United States). Dept. of Ocean Engineering

    1996-12-31

    A towed multi-channel FM acoustic reflection profiler has been developed for locating and generating images of buried objects. One significant application of this sonar is buried pipeline surveying. The multi-channel reflection profiler uses 16 line arrays mounted in a towed vehicle to determine the position and burial depth of an 18 inch steel pipe filled with concrete buried under 1.5 meters of sand. This sonar will allow a survey vessel to continuously track a buried pipeline providing a continuous record of pipe burial depth and position.

  9. Studies relating to FM television and telemetry transmitters

    NASA Technical Reports Server (NTRS)

    Albritton, W. P.; Honnell, M. A.

    1972-01-01

    The Auburn University Model S-2 FM television transmitter was examined to determine if the performance and reliability could be improved by application of new techniques and devices developed since completion of the original design work. In particular this study examined the possibility of increased use of integrated circuits. It was determined that improvements in both performance and reliability were possible. In addition a study was conducted to determine the feasibility of converting the transmitter to handle telemetry signals. The study revealed that this conversion was feasible and the modifications were made to the prototype model for verification.

  10. 76 FR 28983 - Media Bureau Seeks Comment on the Economic Impact of Low-Power FM Stations on Full-Service...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-19

    ...of Low-Power FM Stations on Full-Service Commercial FM Stations...of low-power FM stations on full-service commercial FM stations...May 10, 2011. The complete text of the document is available...low-power FM stations will have on full-service commercial FM...

  11. Lidar waveform stacking techniques for faint ground return extraction

    NASA Astrophysics Data System (ADS)

    Magruder, Lori A.; Neuenschwander, Amy L.; Marmillion, Scott P.

    2010-01-01

    Innovative algorithm development for small-footprint full-waveform lidar data processing extends this technology's capabilities to more complicated acquisition scenarios then previously determined, namely success of surveys over obscured areas. Waveform decomposition and the extraction of waveform metrics provide a straightforward approach to identifying vertical structure within each laser measurement. However, there are some limitations in this approach as faint returns within the waveform go undetected within the classical processing chain. These faint returns are the result of reduced energy levels due to obscurant scattering, attenuation and absorption. Lidar surveys over non-homogeneous wooded regions indicate that there are meaningful ground returns within dense tree coverage if extracted correctly from the data. By using a waveform stacking technique with appropriate waveforms in near geospatial proximity to the original, these faint returns can be augmented and detected during data processing. In comparison to the traditional approach, the waveform stacking technique provides up to a 60% increase in perceived ground returns with the faint signal extraction for the particular datasets analyzed over a broadleaf forest in Mississippi. The enhanced capability in the presence of foliage provides a decrease in operational effort associated with data density, dwell or targeting techniques, in addition to required survey expense.

  12. Deconvolution of multi-peak ICESat/GLAS waveforms

    NASA Astrophysics Data System (ADS)

    Neuenschwander, A.; Urban, T. J.; Webb, C. E.; Schutz, B.

    2007-12-01

    Although primarily designed for cryosphere studies, data from ICESat/GLAS currently provide the only source of global vegetation height mapping. The objective of this research is to examine the methodological techniques and accuracy of lidar waveform analysis for 3d vertical structure using ICESat/GLAS. This research will investigate the ranging techniques and methods (deconvolution and decomposition) for discriminating various features or reflecting surfaces within each returned waveform. The returned waveform energy detected by the digitizer is a function of the scattering elements within the energy path and the impulse response of the system. By knowing the impulse response of the system, this signal can be removed from the return waveform to improve separability between targets along the laser path. Heights derived from the deconvolution methodology will be assessed against heights derived from Gaussian decomposition of the returned waveform. Here, the assumption that the return waveform is a modeled composite of Gaussian distributions from multiple scatters falling along the laser path. This is currently the technique (up to 6 Gaussians) that is implemented on ICESat/GLAS processing. The White Sands Missile Range (WSMR) Space Harbor area in New Mexico is used as a precision calibration and validation site for ICESat, with experiments operated and maintained by the University of Texas at Austin Center for Space Research (UTCSR). The returned waveforms from an array of corner-cube reflectors placed on poles of known heights located at the WSMR will be used to evaluate the deconvolution and decomposition results.

  13. Shoreline Mapping Using Lidar Red-Channel Waveforms

    NASA Astrophysics Data System (ADS)

    Pe'Eri, S.; Philpot, W. D.; Guenther, G. C.; Gardner, J. V.

    2006-12-01

    The determination of the shoreline is the basis for defining boundaries between private, state, and federal ownership and jurisdictions, including the territorial sea and the Exclusive Economic Zone. Though the use of airborne lidar bathymetry (ALB) is not new, there is still a need for more reliable results using ALB in defining the shorelines. Previous algorithms for defining the shoreline (land-water determination) have used; (1) the presence of a saturated peak in the infrared-channel waveforms, or (2) a ratio between the green-channel, red- channel and infrared-channel waveforms. Research and development for both algorithms were applied to the older SHOALS-400 lidar that varies in dynamic range and waveform record length from the current SHOALS- 1000/3000 lidars. Observations of the red-channel waveforms show a strong dependence between the waveform and the presence of water. Different waveform characteristics are found from water and land returns (bare earth and vegetation coverage). We present here an algorithm for distinguishing land or water using the lidar red-channel waveforms. The data for this study are from (1) the 2000-2001 USGS surveys in Lake Michigan and Lake Tahoe, CA using the SHOALS-400 lidar system and (2) the NOAA survey in the Isles of Shoals, NH-ME using the SHOALS-1000. The algorithm shows good preliminary results both for the older and the current SHOALS systems. Aerial photogrammetry was used as reference data to support the findings.

  14. Extension of high-order harmonic generation cutoff via coherent control of intense few-cycle chirped laser pulses

    E-print Network

    Carrera, Juan J.; Chu, Shih-I

    2007-03-16

    We present an ab initio quantum investigation of the high-order harmonic generation (HHG) cutoff extension using intense few-cycle chirped laser pulses. For a few-cycle chirped driving laser pulse, it is shown that significant cutoff extension can...

  15. Detecting subtle differences in behavior using waveform display analysis.

    PubMed

    Campbell, K M; Rohland, R M; McGrath, M J; Satoskar, S D; Burton, F H

    1998-04-01

    We have devised a method, behavioral waveform display analysis, to analyze complex ethological information by measuring behavior in real time and visualizing it as a time-dependent, multistate waveform. To facilitate the generation and statistical analysis of behavioral waveform displays, we have designed a simple Macintosh-based software program. When keystrokes coded to particular behavioral states are entered in real time, this software measures and collates the time, frequency, and duration of each behavioral state. These data can then be displayed either in a tabular format for statistical analysis of behavioral duration and frequency or as graphical coordinates for creating waveform displays by direct importing into graphing programs. An illustration of the use of waveform display analysis to detect anomalous behaviors in cocaine- and amphetamine-treated mice, some of which are not detectable by a standard time-sampling assay, is shown. Both waveform display and time-sampling analysis detected drug-induced changes in sniffing, bar hanging, digging, and rearing. However, unlike time-sampling analysis, waveform display analysis also detected changes in the total duration, frequency, and average duration of these behaviors as well as additional changes in gnawing and locomotion. Additionally, visual scanning of behavioral waveform displays detected drug-induced changes in the patterns of behavior not detectable by time-sampling, including 1) a staged progression to a limited behavioral repertoire consisting of sniffing, locomotion, and rearing; 2) rapid switching between these remaining few behaviors; 3) a delayed onset of postinjection rearing relative to sniffing and locomotion; and 4) the absence of other transient stereotypies during the onset of drug action. These data indicate that behavioral waveform display provides an approach for the detection, visualization, and statistical analysis of aspects of complex behavior not amenable to detection by time-sampling methods. PMID:9661986

  16. Experimental demonstration of energy-chirp compensation by a tunable dielectric-based structure.

    PubMed

    Antipov, S; Baturin, S; Jing, C; Fedurin, M; Kanareykin, A; Swinson, C; Schoessow, P; Gai, W; Zholents, A

    2014-03-21

    A tunable energy-chirp compensator was used to remove a correlated energy chirp from the 60-MeV beam at the Brookhaven National Laboratory Accelerator Test Facility. The compensator operates through the interaction of the wakefield of the electron bunch with itself and consists of a planar structure comprised of two alumina bars with copper-plated backs separated by an adjustable beam aperture. By changing the gap size, the correlated energy chirp of the electron bunch was completely removed. Calculations show that this device, properly scaled to account for the electron bunch charge and length, can be used to remove residual correlated energy spread at the end of the linacs used for free-electron lasers. The experimental results are shown to be in good agreement with numerical simulations. Application of this technique can significantly simplify linac design and improve free-electron lasers performance. PMID:24702378

  17. Self-deflecting plasmonic lattice solitons and surface modes in chirped plasmonic arrays.

    PubMed

    Li, Chunyan; Cui, Ran; Ye, Fangwei; Kartashov, Yaroslav V; Torner, Lluis; Chen, Xianfeng

    2015-03-15

    We show that chirped metal-dielectric waveguide arrays with focusing cubic nonlinearity can support plasmonic lattice solitons that undergo self-deflection in the transverse plane. Such lattice solitons are deeply subwavelength self-sustained excitations, although they cover several periods of the array. Upon propagation, the excitations accelerate in the transverse plane and follow trajectories curved in the direction in which the separation between neighboring metallic layers decreases, a phenomenon that yields considerable deflection angles. The deflection angle can be controlled by varying the array chirp. We also reveal the existence of surface modes at the boundary of truncated plasmonic chirped array that form even in the absence of nonlinearity. PMID:25768141

  18. Self-referenced characterization of femtosecond laser pulses by chirp scan.

    PubMed

    Loriot, Vincent; Gitzinger, Gregory; Forget, Nicolas

    2013-10-21

    We investigate a variant of the d-scan technique, an intuitive pulse characterization method for retrieving the spectral phase of ultrashort laser pulses. In this variant a ramp of quadratic spectral phases is applied to the input pulses and the second harmonic spectra of the resulting pulses are measured for each chirp value. We demonstrate that a given field envelope produces a unique and unequivocal chirp-scan map and that, under some asymptotic assumptions, both the spectral amplitude and phase of the measured pulse can be retrieved analytically from only two measurements. An iterative algorithm can exploit the redundancy of the information contained in the chirp-scan map to discard experimental noise, artifacts, calibration errors and improve the reconstruction of both the spectral intensity and phase. This technique is compared to two reference characterization techniques (FROG and SRSI). Finally, we perform d-scan measurements with a simple grating-pair compressor. PMID:24150331

  19. Algorithm of matched filtering overcoming nonlinear chirp effect in synthetic aperture ladar

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Xu, Nan; Liu, Liren

    2009-08-01

    Linear chirp laser signal is often employed as the transmitted signal of synthetic aperture laser radar (SAL). However, actual properties of frequency sweep of fiber laser always produces nonlinear terms such as quadratic and higher order terms. Existence of nonlinear terms of frequency produces phase errors during pulse time, leading to blurring of target in range direction and further reduces imaging resolution of range direction. It makes compensation of the nonlinear chirp from laser source a requirement. In this paper, we develop an algorithm of matched filtering in frequency spectrum to overcome the phase error from nonlinear chirp. The results of simulation show that the image in range direction can be well compressed. At the same time, we also analyze effects of signal compression in the range direction under different parameter situations such as reference channel length as well as ratio of nonlinear contribution.

  20. Predicting and testing the chirp rate of whistler-mode chorus

    NASA Astrophysics Data System (ADS)

    Cully, C. M.

    2010-12-01

    Chorus emissions are a striking feature of the electromagnetic wave environment near Earth's radiation belts. These bursts of whistler-mode waves exhibit characteristic frequency sweeps (chirps) believed to result from nonlinear wave-particle interactions. Based on the theory of Omura [2008], we demonstrate how to predict the chirp rate of observed chorus elements. The predicted chirp rates are a function of the wave amplitude, and are calculated from available observations leaving no free parameters. We test these predictions against observations from the THEMIS satellites. The predictions agree well with the observations, both in terms of the absolute sweep rates and their relation to the wave amplitudes, lending strong support to the theory that these waves are the result of cyclotron-resonant wave-particle trapping.

  1. Experimental Demonstration of Energy-Chirp Compensation by a Tunable Dielectric-Based Structure

    NASA Astrophysics Data System (ADS)

    Antipov, S.; Baturin, S.; Jing, C.; Fedurin, M.; Kanareykin, A.; Swinson, C.; Schoessow, P.; Gai, W.; Zholents, A.

    2014-03-01

    A tunable energy-chirp compensator was used to remove a correlated energy chirp from the 60-MeV beam at the Brookhaven National Laboratory Accelerator Test Facility. The compensator operates through the interaction of the wakefield of the electron bunch with itself and consists of a planar structure comprised of two alumina bars with copper-plated backs separated by an adjustable beam aperture. By changing the gap size, the correlated energy chirp of the electron bunch was completely removed. Calculations show that this device, properly scaled to account for the electron bunch charge and length, can be used to remove residual correlated energy spread at the end of the linacs used for free-electron lasers. The experimental results are shown to be in good agreement with numerical simulations. Application of this technique can significantly simplify linac design and improve free-electron lasers performance.

  2. Generation of an isolated sub-40-as pulse using two-color laser pulses: Combined chirp effects

    SciTech Connect

    Feng, Liqiang [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China); Chu, Tianshu [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 (China); Institute for Computational Sciences and Engineering, Laboratory of New Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao, 266071 (China)

    2011-11-15

    In this paper, we theoretically discuss the combined chirp effects on the isolated attosecond generation when a model Ar is exposed to an intense 5-fs, 800-nm fundamental chirped pulse combined with a weak 10-fs, 1200-nm controlling chirped pulse. It shows that for the case of the chirp parameters {beta}{sub 1} = 6.1 (corresponding to the 800-nm field) and {beta}{sub 2} = 4.0 (corresponding to the 1200-nm field), both the harmonic cutoff energy and the supercontinuum can be remarkably extended resulting in a 663-eV bandwidth. Moreover, due to the introduction of the chirps, the short quantum path is selected to contribute to the harmonic spectrum. Finally, by superposing a properly selected harmonic spectrum in the supercontinuum region, an isolated pulse as short as 31 as (5 as) is generated without (with) phase compensation.

  3. Gravitational waveforms for black hole binaries with unequal masses

    E-print Network

    Márton Tápai; Zoltán Keresztes; László Árpád Gergely

    2012-10-25

    We derived a post-Newtonian (PN) inspiral only gravitational waveform for unequal mass, spinning black hole binaries. Towards the end of the inspiral the larger spin dominates over the orbital angular momentum (while the smaller spin is negligible), hence the name Spin-Dominated Waveforms (SDW). Such systems are common sources for future gravitational wave detectors and during the inspiral the largest amplitude waves are emitted exactly in its last part. The SDW waveforms emerge as a double expansion in the PN parameter and the ratio of the orbital angular momentum to the dominant spin.

  4. A 10 tesla table-top controlled waveform magnet

    NASA Astrophysics Data System (ADS)

    Roy Choudhury, Aditya N.; Venkataraman, V.

    2012-06-01

    Controlled Waveform Magnets (CWMs) are a special class of pulsed magnets which provide semi-continuous, shape-controlled high magnetic field pulses. In this work we report a table-top CWM, driven by a capacitor bank, capable of producing virtually any user-shaped magnetic field waveform up to 10 Tesla. Insulated Gate Bipolar Transistor (IGBT) chips were paralleled to form the high current switch. Specimen pulse shapes including flat-tops up to 10 Tesla, and linear as well as some sinusoidal-top magnetic field waveforms have been successfully generated.

  5. General Dynamic (GD) Launch Waveform On-Orbit Performance Report

    NASA Technical Reports Server (NTRS)

    Briones, Janette C.; Shalkhauser, Mary Jo

    2014-01-01

    The purpose of this report is to present the results from the GD SDR on-orbit performance testing using the launch waveform over TDRSS. The tests include the evaluation of well-tested waveform modes, the operation of RF links that are expected to have high margins, the verification of forward return link operation (including full duplex), the verification of non-coherent operational models, and the verification of radio at-launch operational frequencies. This report also outlines the launch waveform tests conducted and comparisons to the results obtained from ground testing.

  6. Enhance cognitive radar security by designing optimal waveform

    NASA Astrophysics Data System (ADS)

    Wang, Songbai; Wang, Jian; Chen, Jianshu; Shan, Xiuming

    2011-10-01

    In this paper, we consider cognitive radar security in the presence of interceptors. By designing waveform, the cognitive radar will spread its most power to match the target channel for estimation and remove the spectrum that matches the interception channel for security. We firstly propose the signal model of a typical scenario, and then use the mutual information criterion to guide waveform design. By solving a convex optimization problem, we can obtain a globally optimal waveform. This paper also presents numerical examples to verify effectiveness of the idea and the approaches.

  7. Variability of extracellular spike waveforms of cortical neurons.

    PubMed

    Fee, M S; Mitra, P P; Kleinfeld, D

    1996-12-01

    1. Here we study the variability in extracellular records of action potentials. Our work is motivated, in part, by the need to construct effective algorithms to classify single-unit waveforms from multiunit recordings. 2. We used microwire electrode pairs (stereotrodes) to record from primary somatosensory cortex of awake, behaving rat. Our data consist of continuous records of extracellular activity and segmented records of extracellular spikes. Spectral and principal component techniques are used to analyze mean single-unit wave-forms, the variability between different instances of a single-unit waveform, and the underlying background activity. 3. The spectrum of the variability between different instances of a single-unit waveforms is not white, and falls off above 1 kHz with a frequency dependence of roughly f-2. This spectrum is different from that of the mean spike waveforms, which falls off roughly as f-4, but is essentially identical with the spectrum of background activity. The spatial coherence of the variability on the 10-micron scale also falls off at high frequencies. 4. The variability between different instances of a single-unit waveform is dominated by a relatively small number of principal components. As a consequence, there is a large anisotropy in the cluster of the spike waveforms. 5. The background noise cannot be represented as a stationary Gaussian random process. In particular, we observed that the spectrum changes significantly between successive 20-ms intervals. Furthermore, the total power in the background activity exhibits larger fluctuations than is consistent with a stationary Gaussian random process. 6. Roughly half of the single-unit spike waveforms exhibit systematic changes as a function of the interspike interval. Although this results in a non-Gaussian distribution in the space of waveforms, the distribution can be modeled by a scalar function of the interspike interval. 7. We use a set of 44 mean single-unit waveforms to define the space of differences between spike waveforms. This characterization, together with that of the background activity, is used to construct a filter that optimizes the detection of differences between single-unit waveforms. Further, an information theoretic measure is defined that characterizes the detectability. PMID:8985880

  8. Gravitational radiation reaction and inspiral waveforms in the adiabatic limit.

    PubMed

    Hughes, Scott A; Drasco, Steve; Flanagan, Eanna E; Franklin, Joel

    2005-06-10

    We describe progress evolving an important limit of binaries in general relativity: stellar mass compact objects spiraling into much larger black holes. Such systems are of great observational interest. We have developed tools to compute for the first time the radiation from generic orbits. Using global conservation laws, we find the orbital evolution and waveforms for special cases. For generic orbits, inspirals and waveforms can be found by augmenting our approach with an adiabatic self-force rule due to Mino. Such waveforms should be accurate enough for gravitational-wave searches. PMID:16090377

  9. Frequency Correction for MIRO Chirp Transformation Spectroscopy Spectrum

    NASA Technical Reports Server (NTRS)

    Lee, Seungwon

    2012-01-01

    This software processes the flyby spectra of the Chirp Transform Spectrometer (CTS) of the Microwave Instrument for Rosetta Orbiter (MIRO). The tool corrects the effect of Doppler shift and local-oscillator (LO) frequency shift during the flyby mode of MIRO operations. The frequency correction for CTS flyby spectra is performed and is integrated with multiple spectra into a high signal-to-noise averaged spectrum at the rest-frame RF frequency. This innovation also generates the 8 molecular line spectra by dividing continuous 4,096-channel CTS spectra. The 8 line spectra can then be readily used for scientific investigations. A spectral line that is at its rest frequency in the frame of the Earth or an asteroid will be observed with a time-varying Doppler shift as seen by MIRO. The frequency shift is toward the higher RF frequencies on approach, and toward lower RF frequencies on departure. The magnitude of the shift depends on the flyby velocity. The result of time-varying Doppler shift is that of an observed spectral line will be seen to move from channel to channel in the CTS spectrometer. The direction (higher or lower frequency) in the spectrometer depends on the spectral line frequency under consideration. In order to analyze the flyby spectra, two steps are required. First, individual spectra must be corrected for the Doppler shift so that individual spectra can be superimposed at the same rest frequency for integration purposes. Second, a correction needs to be applied to the CTS spectra to account for the LO frequency shifts that are applied to asteroid mode.

  10. Evaluation of chirp reversal power modulation sequence for contrast agent imaging

    NASA Astrophysics Data System (ADS)

    Novell, A.; Sennoga, CA; Escoffre, JM; Chaline, J.; Bouakaz, A.

    2014-09-01

    Over the last decade, significant research effort has been focused on the use of chirp for contrast agent imaging because chirps are known to significantly increase imaging contrast-to-noise ratio (CNR). New imaging schemes, such as chirp reversal (CR), have been developed to improve contrast detection by increasing non-linear microbubble responses. In this study we evaluated the contrast enhancement efficiency of various chirped imaging sequences in combination with well-established imaging schemes such as power modulation (PM) and pulse inversion (PI). The imaging schemes tested were implemented on a fully programmable open scanner and evaluated by ultrasonically scanning (excitation frequency of 2.5?MHz amplitude of 350?kPa) a tissue-mimicking flow phantom comprising a 4?mm diameter tube through which aqueous dispersions (dilution fraction of 1/2000) of the commercial ultrasound contrast agent, SonoVue® were continuously circulated. The recovery of non-linear microbubble responses after chirp compression requires the development and the optimization of a specific filter. A compression filter was therefore designed and used to compress and extract several non-linear components from the received microbubble responses. The results showed that using chirps increased the image CNR by approximately 10?dB, as compared to conventional Gaussian apodized sine burst excitation but degraded the axial resolution by a factor of 1.4, at -3?dB. We demonstrated that the highest CNR and contrast-to-noise ratio (CTR) were achievable when CR was combined with PM as compared to other imaging schemes such as PI.

  11. Chirped pulse Raman amplification in Ba(NO3)2 crystals

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyang; Lu, Jun; Li, Wenkai; Xu, Yi; Lu, Xiaoming; Leng, Yuxin; Li, Ruxin

    2015-04-01

    In this study, 35.5% conversion efficiency is obtained at the first Stokes component frequency (873 nm) upon two-stage chirped pulse Raman amplification in a Ba(NO3)2 crystal by an 8 mJ, 620 ps, 800 nm pump laser. A maximum energy of 4.22 mJ with 3.82% rms stability at the first Stokes pulse can be obtained under 35 mJ pump energy. Moreover, the chirped first Stokes pulse can be compressed to 143 fs.

  12. Microjoule pulse energy from a chirped-pulse Ti:sapphire oscillator with cavity dumping.

    PubMed

    Siegel, Martin; Pfullmann, Nils; Palmer, Guido; Rausch, Stefan; Binhammer, Thomas; Kovacev, Milutin; Morgner, Uwe

    2009-03-15

    We demonstrate a chirped-pulse Ti:sapphire laser oscillator with both Kerr-lens and semiconductor- saturable-absorber-mirror-assisted mode locking generating 1.1 microJ pulses at 1 MHz pulse repetition rate. The pulses are coupled out of the laser cavity by means of an acousto-optical cavity dumper, have a spectral width that supports a Fourier limit of 74 fs, and currently have a chirped-pulse duration of 5 ps. After compressing the pulses, this laser will be an ideal tool for efficient high-harmonic generation directly from a laser oscillator. PMID:19282917

  13. Practical design of optical diagnostics for chirped-pulse free-electron lasers

    NASA Astrophysics Data System (ADS)

    Szarmes, Eric B.; Madey, John M. J.

    1992-07-01

    In recent years there have been several proposals to operate rf-linac-driven FELs with chirped electron and optical micropulses for use in fast time-resolved experiments. We have been actively pursuing this application on the Mark-III infrared FEL at Duke University, and have designed and procured an apparatus to achieve broad-band compression of chirped optical pulses between roughly 2.5 ?m and 4.1 ?m, with subsequent measurement of pulse widths as short as 200 fs. The principles of design for this experiment will be reviewed, and extensions of the design to other wavelengths will be considered.

  14. Noise filtering in parametric amplification by dressing the seed beam with spatial chirp.

    PubMed

    Wang, Jing; Ma, Jingui; Wang, Yongzhi; Yuan, Peng; Xie, Guoqiang; Qian, Liejia

    2014-04-15

    We report a method for filtering out the noises produced in optical parametric chirped-pulse amplifiers by dressing the seed beam with spatial chirp. After dechirping the amplified signal with a compressor, the noises experience a spatiotemporal coupling, making themselves highly distinguishable from the compressed signal in space, and hence supporting noise filtering effectively and expediently in the spatial domain, which would otherwise not be possible. Numerical simulations performed for the proposed method show the capabilities of an order of magnitude reduction in the noise energy and several orders of magnitude enhancement in the temporal contrast. PMID:24979013

  15. Reflectivity of linear and nonlinear gamma radiated apodized chirped Bragg grating under ocean

    SciTech Connect

    Hamdalla, Taymour A. [Faculty of Science, Alexandria University, Alexandria (Egypt); Faculty of Science, Tabuk University, Tabuk (Saudi Arabia)

    2012-09-06

    In this paper, the effect Co{sup 60} gamma radiation is investigated on the effective refractive index of apodized chirped Bragg grating. Nine apodization profiles are considered. Comparison between the reflectivity of the gamma radiated and non radiated fiber Bragg grating has been carried out. The electric field of signals propagating through the apodized chirped fiber Bragg grating (ACFBG) is first calculated from which, new values for the refractive index are determined. The nonlinear effects appear on the ACFBG reflectivity. The effect of nonlinearity and undersea temperature and pressure on the grating is also studied.

  16. Dynamics of surface solitons at the edge of chirped optical lattices

    NASA Astrophysics Data System (ADS)

    Kartashov, Yaroslav V.; Vysloukh, Victor A.; Torner, Lluis

    2007-07-01

    We address soliton formation at the edge of chirped optical lattices imprinted in Kerr-type nonlinear media. We find families of power thresholdless surface waves that do not exist at other types of lattice interfaces. Such solitons form due to combined action of internal reflection at the interface, distributed Bragg-type reflection, and focusing nonlinearity. Remarkably, we discover that surfaces of chirped lattices are soliton attractors: Below an energy threshold, solitons launched well within the lattice self-bend toward the interface, and then stick to it.

  17. Chirped pulse reflectivity and frequency domain interferometry in laser driven shock experiments.

    PubMed

    Benuzzi-Mounaix, A; Koenig, M; Boudenne, J M; Hall, T A; Batani, D; Scianitti, F; Masini, A; Di Santo, D

    1999-09-01

    We show the simultaneous applicability of the frequency domain interferometry and the chirped pulse reflectometry techniques to measure shock parameters. The experiment has been realized with the laser at the Laboratoire pour l'Utilisation des Lasers Intenses (LULI) with a 550-ps pulse duration and an intensity on target approximately 5 x 10(13) W/cm(2) to produce a shock in a layered aluminum-fused silica target. A second low energy, partially compressed chirped probe beam was used to irradiate the target rear side and the reflected light has been analyzed with a spectrometer, achieving a temporal resolution of the order of 1 ps. PMID:11970183

  18. Inversion method for initial tsunami waveform reconstruction

    NASA Astrophysics Data System (ADS)

    Voronin, V. V.; Voronina, T. A.; Tcheverda, V. A.

    2014-12-01

    This paper deals with the application of r-solution method to recover the initial tsunami waveform in a tsunami source area by remote water-level measurements. Wave propagation is considered within the scope of a linear shallow-water theory. An ill-posed inverse problem is regularized by means of least square inversion using a truncated SVD approach. The properties of obtained solution are determined to a large extent by the properties of an inverse operator, which were numerically investigated. The method presented allows one to control instability of the numerical solution and to obtain an acceptable result in spite of ill-posedness of the problem. It is shown that the accuracy of tsunami source reconstruction strongly depends on the signal-to-noise ratio, the azimuthal coverage of recording stations with respect to the source area and bathymetric features along the wave path. The numerical experiments were carried out with synthetic data and various computational domains including a real bathymetry. The method proposed allows us to make a preliminary prediction of the efficiency of the inversion with a given set of the recording stations and to find out the most informative part of the existing observation system. This essential property of the method can prove to be useful in designing a monitoring system for tsunamis.

  19. Femtosecond Nanofocusing with Full Optical Waveform Control

    SciTech Connect

    Berweger, Samuel; Atkin, Joanna M.; Xu, Xiaoji G.; Olmon, Robert L.; Raschke, Markus Bernd

    2011-10-12

    The simultaneous nanometer spatial confinement and femtosecond temporal control of an optical excitation has been a long-standing challenge in optics. Previous approaches using surface plasmon polariton (SPP) resonant nanostructures or SPP waveguides have suffered from, for example, mode mismatch, or possible dependence on the phase of the driving laser field to achieve spatial localization. Here we take advantage of the intrinsic phase- and amplitude-independent nanofocusing ability of a conical noble metal tip with weak wavelength dependence over a broad bandwidth to achieve a 10 nm spatially and few-femtosecond temporally confined excitation. In combination with spectral pulse shaping and feedback on the second-harmonic response of the tip apex, we demonstrate deterministic arbitrary optical waveform control. In addition, the high efficiency of the nanofocusing tip provided by the continuous micro- to nanoscale mode transformation opens the door for spectroscopy of elementary optical excitations in matter on their natural length and time scales and enables applications from ultrafast nano-opto-electronics to single molecule quantum coherent control.

  20. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

    SciTech Connect

    Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

    2009-04-30

    High-Resolution Source Parameters using Calibration from Ambient Seismic Noise (ASN) Zhongwen Zhan, Shengji Wei, Sidao Ni, and Don V. Helmberger Abstract Several new methods have been developed to retrieve local Green's functions based on the cross-correlation of ambient seismic noise (station-to-station) and conventional (source-to-station) inversions. The latter methods provide the most broadband results but require accurate source parameters for phase-delay recovery which depends on the starting model. Considerable progress is being made in providing such information from 3D modeling, Tape et al. (2008), using Adjoint Tomography. But to match waveforms for the recent Chino Hills event still requires shifting synthetics to align on data. This means that it is difficult to use 3D simulations to refine source locations in near-real time. We can avoid the 3D problems by applying the CAP method and storing shifts from past events, Tan (2006), and/or using ASN, Shapiro et al. (2005), to predict lags for surface waves. Here, we directly compare results from CAP predictions with ASN results using stations near the Chino Hills event. We use the same SC seismic model as used in the Library of Earthquakes to generate Green's functions for noise (single force) for comparison with ASN correlations and allow Cap delays. We apply these delays or corrections to determine precise Centroid locations.

  1. Flagellar waveform analysis of swimming algal cells

    NASA Astrophysics Data System (ADS)

    Kurtuldu, Huseyin; Johnson, Karl; Gollub, Jerry

    2011-11-01

    The twin flagella of the green alga Chlamydomas reinhardtii are driven by dynein molecular motors to oscillate at about 50-60 Hz in a breaststroke motion. For decades, Chlamydomas has been used as a model organism for studies of flagellar motility, and of genetic disorders of ciliary motion. However, little is known experimentally about the flagellar waveforms, and the resulting time-dependent force distribution along the 250 nm diameter flagella. Here, we study flagellar dynamics experimentally by confining cells in quasi-2D liquid films. From simultaneous measurements of the cell body velocity and the time-dependent velocities along the center lines of the two flagella, we determine the drag coefficients, and estimate the power expended by the body and the flagella, comparing our findings with measurementsootnotetextJ.S. Guasto et al., Phys. Rev. Lett. 105, 168102 (2010) based on the induced fluid flow field. We contrast the results for the quite different beating patterns of synchronous and asynchronous flagella, respectively.

  2. Monaural and binaural processing of complex waveforms

    NASA Astrophysics Data System (ADS)

    Trahiotis, Constantine; Bernstein, Leslie R.

    1993-01-01

    Data were collected concerning the amount of comodulation masking release (CMR) obtained when coherent envelope information is presented successively rather than simultaneously. It was determined that off-frequency information, which produces a CMR, can provide only a small release from masking when presented prior and subsequent to the temporal interval containing the signal. Three papers were published and a fourth is undergoing revision. One assessed sensitivity to interaural correlation of the envelope of high-frequency waveforms and whether such sensitivity might account for detectability in an MLD paradigm. Another showed sensitivity to antiphasic sinusoids added only to the envelopes of high-frequency bands of noise as a function of the frequency of the sinusoid and the bandwidth of the masker. A third, with Dr. R. M. Stem, depicts how straightness weighting can be accomplished by a second, physiologically demonstrated, stage of neural processing. The complex, cross-correlation-based model was extended to account for how interaural insensitive disparities in combination with interaural temporal disparities affects lateralization. Software was written for experiments concerning effects of forward masking fringes on the high-frequency MLD and to perform the theoretical analyses of stimuli used in the successive CMR paradigm.

  3. Waveform synthesis for imaging and ranging applications

    DOEpatents

    Doerry, Armin W.; Dudley, Peter A.; Dubert, Dale F.; Tise, Bertice L.

    2004-12-07

    Frequency dependent corrections are provided for quadrature imbalance and Local Oscillator (LO) feed-through. An operational procedure filters imbalance and LO feed-through effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver; unwanted energies, such as LO feed-through and/or imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of LO feed-through and imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.

  4. In silico estimates of cell electroporation by electrical incapacitation waveforms

    E-print Network

    Weaver, James C.

    We use a system model of a cell and approximate magnitudes of electrical incapacitation (EI) device waveforms to estimate conditions that lead to responses with or without electroporation (EP) of cell membranes near ...

  5. Subpicosecond single-shot waveform measurement using temporal imaging

    SciTech Connect

    Bennett, C V; Kolner, B H

    1999-07-19

    Experimental results from a new single-transient optical recorder with < 300 fs resolution are presented. The system uses a 103x temporal imaging system to expand the waveform which is then recorded with a streak camera.

  6. Acoustic Waveform Logging - Advances In Theory And Application

    E-print Network

    Cheng, C. H.

    Full-waveform acoustic logging has made significant advances in both theory and application in recent years, and these advances have greatly increased the capability of log analysts to measure the physical properties of ...

  7. Solving seismological problems using sgraph program: II-waveform modeling

    SciTech Connect

    Abdelwahed, Mohamed F. [Geological Hazards Research Unit, King Abdulaziz University (Saudi Arabia) and National Research Institute of Astronomy and Geophysics (NRIAG), Helwan (Egypt)

    2012-09-26

    One of the seismological programs to manipulate seismic data is SGRAPH program. It consists of integrated tools to perform advanced seismological techniques. SGRAPH is considered a new system for maintaining and analyze seismic waveform data in a stand-alone Windows-based application that manipulate a wide range of data formats. SGRAPH was described in detail in the first part of this paper. In this part, I discuss the advanced techniques including in the program and its applications in seismology. Because of the numerous tools included in the program, only SGRAPH is sufficient to perform the basic waveform analysis and to solve advanced seismological problems. In the first part of this paper, the application of the source parameters estimation and hypocentral location was given. Here, I discuss SGRAPH waveform modeling tools. This paper exhibits examples of how to apply the SGRAPH tools to perform waveform modeling for estimating the focal mechanism and crustal structure of local earthquakes.

  8. Optimization of Geoscience Laser Altimeter System waveform metrics to support vegetation measurements

    E-print Network

    Lefsky, Michael

    noise and signal-to-noise ratio of the waveform, as the background noise contribution to the waveforms on the power level or the signal-to-noise ratio of waveforms best minimized differences in waveform extent of Lidar, College of Natural Resources, Colorado State University, Fort Collins, CO 80523, USA b Research

  9. Compression strategies for LiDAR waveform cube

    NASA Astrophysics Data System (ADS)

    Jó?ków, Grzegorz; Toth, Charles; Quirk, Mihaela; Grejner-Brzezinska, Dorota

    2015-01-01

    Full-waveform LiDAR data (FWD) provide a wealth of information about the shape and materials of the surveyed areas. Unlike discrete data that retains only a few strong returns, FWD generally keeps the whole signal, at all times, regardless of the signal intensity. Hence, FWD will have an increasingly well-deserved role in mapping and beyond, in the much desired classification in the raw data format. Full-waveform systems currently perform only the recording of the waveform data at the acquisition stage; the return extraction is mostly deferred to post-processing. Although the full waveform preserves most of the details of the real data, it presents a serious practical challenge for a wide use: much larger datasets compared to those from the classical discrete return systems. Atop the need for more storage space, the acquisition speed of the FWD may also limit the pulse rate on most systems that cannot store data fast enough, and thus, reduces the perceived system performance. This work introduces a waveform cube model to compress waveforms in selected subsets of the cube, aimed at achieving decreased storage while maintaining the maximum pulse rate of FWD systems. In our experiments, the waveform cube is compressed using classical methods for 2D imagery that are further tested to assess the feasibility of the proposed solution. The spatial distribution of airborne waveform data is irregular; however, the manner of the FWD acquisition allows the organization of the waveforms in a regular 3D structure similar to familiar multi-component imagery, as those of hyper-spectral cubes or 3D volumetric tomography scans. This study presents the performance analysis of several lossy compression methods applied to the LiDAR waveform cube, including JPEG-1, JPEG-2000, and PCA-based techniques. Wide ranges of tests performed on real airborne datasets have demonstrated the benefits of the JPEG-2000 Standard where high compression rates incur fairly small data degradation. In addition, the JPEG-2000 Standard-compliant compression implementation can be fast and, thus, used in real-time systems, as compressed data sequences can be formed progressively during the waveform data collection. We conclude from our experiments that 2D image compression strategies are feasible and efficient approaches, thus they might be applied during the acquisition of the FWD sensors.

  10. FM-GA and CM-GA for gene microarray analysis.

    PubMed

    Liang, Lily R; Palomino, Rommel A Benites; Lu, Zhao; Mandal, Vinay; Kumar, Deepak

    2010-01-01

    In this paper, we propose two new approaches, FM-GA and CM-GA, to identify significant genes from microarray datasets. FM-GA and CM-GA combine our innovative FM-test and CM-test with genetic algorithm (GA), respectively, and leverage the strengths of GA. The performance of FM-GA and CM-GA was evaluated by the classification accuracy of decision trees constructed with the selected genes. Experiments were conducted to demonstrate the superiority of the proposed method over other approaches. PMID:20865502

  11. Mass distributions for thermal-neutron-induced fission of 255Fm and 251Cf

    Microsoft Academic Search

    K. F. Flynn; J. E. Gindler; R. K. Sjoblom; L. E. Glendenin

    1975-01-01

    Mass distributions for thermal-neutron-induced fission (n, f) of 255Fm and 251Cf have been determined radiochemically. Both mass distributions are asymmetric with a peak-to-valley ratio of about 2.6 for 255Fm and about 13 for 251Cf. Cross sections were determined to be 3200+\\/-320 b for 255Fm(n, f) and 5300+\\/-530 b for 251Cf(n, f). NUCLEAR REACTIONS, FISSION 255Fm(n, f), 251Cf(n, f), E=0.025 eV;

  12. Speech waveform encoding using contour gain vector quantization

    E-print Network

    Malone, Kevin Thomas

    1985-01-01

    SPEECH WAVEFORM ENCODING USING CONTOUR GAIN VECTOR QUANTIZATION A Thesis by KEVIN THOMAS MALONE Submitted to the Graduate College of Texas A k M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May... 1985 Major Subject: Electrical Engineering SPEECH WAVEFORM ENCODING USING CONTOUR GAIN VECTOR QUANTIZATION A Thesis by KEVIN THOMAS MALONE Approved as to style and content by: Thomas R. Fischer (Chairman of Committee) Noel R. Strader (Member...

  13. Waveform-space-time adaptive processing for distributed aperture radars

    Microsoft Academic Search

    Raviraj S. Adve; Richard A. Schneible; Gerard Genello; Paul Antonik

    2005-01-01

    This paper presents the preliminary development of adaptive signal processing for distributed, waveform diverse, antenna arrays. The long term goal is to develop practical waveform-time-space adaptive processing algorithms for distributed apertures. A crucial issue identified in previous works is that, in practice, the target and interfering sources are not in the far-field of the antenna array. Recent work by the

  14. HBM tester waveforms, equivalent circuits, and socket capacitance

    Microsoft Academic Search

    Timothy J. Maloney

    2010-01-01

    The Tektronix CT2 current probe is used to acquire more accurate Human Body Model waveforms with 0-ohm and 500 ohm tester loads than a CT1, owing to the CT2's low-frequency performance. The integrals and centroids of these waveforms then readily yield precise values of tester circuit elements and effective socket capacitance. Expressions are derived for effective socket capacitance resulting from

  15. System and Method for Generating a Frequency Modulated Linear Laser Waveform

    NASA Technical Reports Server (NTRS)

    Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)

    2014-01-01

    A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

  16. Quantification of wave reflection using peripheral blood pressure waveforms.

    PubMed

    Kim, Chang-Sei; Fazeli, Nima; McMurtry, M Sean; Finegan, Barry A; Hahn, Jin-Oh

    2015-01-01

    This paper presents a novel minimally invasive method for quantifying blood pressure (BP) wave reflection in the arterial tree. In this method, two peripheral BP waveforms are analyzed to obtain an estimate of central aortic BP waveform, which is used together with a peripheral BP waveform to compute forward and backward pressure waves. These forward and backward waves are then used to quantify the strength of wave reflection in the arterial tree. Two unique strengths of the proposed method are that 1) it replaces highly invasive central aortic BP and flow waveforms required in many existing methods by less invasive peripheral BP waveforms, and 2) it does not require estimation of characteristic impedance. The feasibility of the proposed method was examined in an experimental swine subject under a wide range of physiologic states and in 13 cardiac surgery patients. In the swine subject, the method was comparable to the reference method based on central aortic BP and flow. In cardiac surgery patients, the method was able to estimate forward and backward pressure waves in the absence of any central aortic waveforms: on the average, the root-mean-squared error between actual versus computed forward and backward pressure waves was less than 5 mmHg, and the error between actual versus computed reflection index was less than 0.03. PMID:25561452

  17. Retracking CryoSat waveforms for near-real-time ocean forecast products, platform attitude, and other applications

    NASA Astrophysics Data System (ADS)

    Smith, W. H.; Scharroo, R.; Lillibridge, J. L.; Leuliette, E. W.

    2011-12-01

    The SIRAL altimeter on CryoSat, launched in 2010, can operate in three modes: the low-rate mode (LRM) behaves as a conventional altimeter; the SAR mode allows more precise range and more focused footprint through use of synthetic aperture radar (SAR), also known as delay-Doppler, processing; the SARIN mode, or interferometric SAR, also affords across-track slope determination from interferometry. We have been working on several CryoSat studies over this year and will present some highlights. For the conventional LRM mode, we have built a retracker that processes near-real-time (FDM: Fast Delivery Mode) and Level 1-B data at 20 Hz to yield wind speed, wave height, and sea surface height anomaly. These data are being fed to NOAA's National Centers for Environmental Prediction. The retracking also estimates the off-nadir mispointing angle of the satellite. After accounting for an effect due to orbit height variations, we find that the off-nadir angle estimates are sufficiently accurate that we have used them to calibrate biases in the pitch and roll of the spacecraft platform reported by the platform attitude control system. These biases account for mis-alignment between the star tracker bench and the antenna boresight. We have Full Bit Rate (FBR) data in SAR mode for some ocean passes, including portions crossing coastlines, both from ocean to land and from land to ocean. FBR data includes all the raw I and Q samples of the raw radar echoes, prior to the range FFT that deramps the chirp, or the azimuth FFT that initiates the delay-Doppler SAR focusing calculation. We are currently working on these data with several applications in mind: (1) We can use these data to trace exactly what happens as the instrument crosses a coastline. (2) We can use these data to derive a LRM (conventional) waveform as well as a SAR waveform, and can compare the performance of these two modes under the same conditions (sea state, propagation, etc.) (3) We can test a conjecture by J R Jensen (IEEE TGARS 1999 37(2), 651-658) that waveform sampling rates should be doubled prior to forming the summed squared power, since squaring doubles frequency. This will show whether higher resolution is potentially available from conventional altimeters. Two forthcoming altimeter satellites, Sentinel-3 and Jason-CS, will have instrument heritage from CryoSat's SIRAL. Therefore the altimeter community should be interested in these new capabilities that we can test with CryoSat.

  18. A LINEARIZATION METHOD FOR A UWB VCO-BASED CHIRP GENERATOR USING DUAL COMPENSATION

    E-print Network

    Gomez-Garcia Alvestegui, Daniel

    2011-12-31

    of a VCO-based chirp generator with 6 GHz of bandwidth. The linearization system is composed of a Phase Lock Loop (PLL) and an external compensation added to the loop. The nonlinear behavior of the VCO was treated as added disturbances to the loop...

  19. Extended Koch's model for chirp assessment in semiconductor singlemode lasers operating at high currents

    NASA Astrophysics Data System (ADS)

    Morgado, José A. P.; Cartaxo, Adolfo V. T.

    2012-11-01

    Semiconductor singlemode laser chirp models that discriminate the adiabatic and the transient frequency chirp components are very relevant and useful, as they allow evaluating per se the effects of both chirp components on directly modulated (DM) laser communication system performance. For this purpose, Koch's model has been extensively used, showing high accuracy for low and moderate laser current regimes. This paper aims at proposing an extended Koch's (e-Koch's) model that allows its accurate use in high current regimes for an arbitrary functional form of the laser nonlinear gain compression factor. High current regimes are commonly found in high bit-rate optical communication systems, in order to achieve sufficient laser intensity modulation bandwidth. Frequency chirping predictions by the proposed model, assessed by numerical simulation, show good agreement with the ones estimated by the laser rate equations, for both linear and logarithmic carrier density dependent laser gain models. It is also shown that e-Koch's model provides good estimates of the performance of 40 Gbit/s DM laser multi-span system.

  20. Fiber optical parametric chirped-pulse amplification in the femtosecond regime

    E-print Network

    Paris-Sud XI, Université de

    . Ishii, L. Turi, V. S. Yakovlev, T. Fuji, F. Krausz, A. Baltuska, R. Butkus, G. Veitas, V. Smilgevicius, R. Danielus, and A. Piskarskas, "Multimillijoule chirped parametric amplification of few. 30, 1974­1976 (2005). 3. I. Jovanovic, C. G. Brown, C. A. Ebbers, C. P. J. Barty, N. Forget, and C

  1. Investigation of wavelength variations of fibre Bragg grating features using a chirped phase mask

    Microsoft Academic Search

    Sui P Yam; D J Kitcher; S A Wade; G W Baxter; S F Collins

    2008-01-01

    A simple scheme, using a chirped phase mask, for studying the wavelength dependence of fibre Bragg grating (FBG) responses in the region of of the Bragg wavelength, which are due to the use of a non-ideal phase mask, is presented. Comparison of the FBG responses in the regions of of the Bragg wavelength (i.e. ?1030 nm) and the usual Bragg

  2. Powerful femtosecond pulse generation by chirped and stretched pulse parametric amplification in BBO crystal

    Microsoft Academic Search

    A. Dubietis; G. Jonusauskas; A. Piskarskas

    1992-01-01

    Chirped pulses have been parametrically amplified by a factor of ~2×104 without bandwidth limitation in BBO crystal. Pulses were compressed down to 70 fs, and ~0.9 GW output power has been obtained. A special technique to match temporal profiles of signal and pump pulses was used.

  3. Individual acoustic variation in Belding's ground squirrel alarm chirps in the High Sierra Nevada (L)

    E-print Network

    Patricelli, Gail

    Individual acoustic variation in Belding's ground squirrel alarm chirps in the High Sierra Nevada membership and is important in kin and social group recognition. Belding's ground squirrels Spermophilus's ground squirrels from four different lakes in the High Sierra Nevada. Results demonstrate that alarm

  4. Time Reversed Transmission with Chirp Signaling for UWB Communications and Its Application in

    E-print Network

    Qiu, Robert Caiming

    for this purpose. Periodically modulated radar returns from jet engines can be modeled as a chirp [6]. This view. II. PULSE PROPAGATION IN RECTANGULAR METAL CAVITY The measurement is performed using frequency domain. The rectangular confined metal cavity in Fig. 1 measures 16 feet by 8 feet by 8 feet. The materials of the walls

  5. The monitoring and multiplexing of fiber optic sensors using chirped laser sources

    E-print Network

    Wan, Xiaoke

    2004-09-30

    A wide band linearly chirped erbium-doped fiber laser has been developed. The erbium-doped fiber laser using a rotating mirror/grating combination as one of the reflectors in a Fabry-Perot laser cavity has been tuned over a 46 nm spectral range...

  6. Simultaneous compression and characterization of ultrashort laser pulses using chirped mirrors and glass wedges.

    PubMed

    Miranda, Miguel; Fordell, Thomas; Arnold, Cord; L'Huillier, Anne; Crespo, Helder

    2012-01-01

    We present a simple and robust technique to retrieve the phase of ultrashort laser pulses, based on a chirped mirror and glass wedges compressor. It uses the compression system itself as a diagnostic tool, thereby making unnecessary the use of complementary diagnostic tools. We used this technique to compress and characterize 7.1 fs laser pulses from an ultrafast laser oscillator. PMID:22274393

  7. ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS

    SciTech Connect

    Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

    2008-04-15

    The recent Nevada Earthquake (M=6) produced an extraordinary set of crustal guided waves. In this study, we examine the three-component data at all the USArray stations in terms of how well existing models perform in predicting the various phases, Rayleigh waves, Love waves, and Pnl waves. To establish the source parameters, we applied the Cut and Paste Code up to distance of 5° for an average local crustal model which produced a normal mechanism (strike=35°,dip=41°,rake=-85°) at a depth of 9 km and Mw=5.9. Assuming this mechanism, we generated synthetics at all distances for a number of 1D and 3D models. The Pnl observations fit the synthetics for the simple models well both in timing (VPn=7.9km/s) and waveform fits out to a distance of about 5°. Beyond this distance a great deal of complexity can be seen to the northwest apparently caused by shallow subducted slab material. These paths require considerable crustal thinning and higher P-velocities. Small delays and advances outline the various tectonic province to the south, Colorado Plateau, etc. with velocities compatible with that reported on by Song et al.(1996). Five-second Rayleigh waves (Airy Phase) can be observed throughout the whole array and show a great deal of variation ( up to 30s). In general, the Love waves are better behaved than the Rayleigh waves. We are presently adding higher frequency to the source description by including source complexity. Preliminary inversions suggest rupture to northeast with a shallow asperity. We are, also, inverting the aftershocks to extend the frequencies to 2 Hz and beyond following the calibration method outlined in Tan and Helmberger (2007). This will allow accurate directivity measurements for events with magnitude larger than 3.5. Thus, we will address the energy decay with distance as s function of frequency band for the various source types.

  8. Full Waveform Inversion of Solar Interior Flows

    NASA Astrophysics Data System (ADS)

    Hanasoge, Shravan M.

    2014-12-01

    The inference of flows of material in the interior of the Sun is a subject of major interest in helioseismology. Here, we apply techniques of full waveform inversion (FWI) to synthetic data to test flow inversions. In this idealized setup, we do not model seismic realization noise, training the focus entirely on the problem of whether a chosen supergranulation flow model can be seismically recovered. We define the misfit functional as a sum of L 2 norm deviations in travel times between prediction and observation, as measured using short-distance filtered f and p 1 and large-distance unfiltered p modes. FWI allows for the introduction of measurements of choice and iteratively improving the background model, while monitoring the evolution of the misfit in all desired categories. Although the misfit is seen to uniformly reduce in all categories, convergence to the true model is very slow, possibly because it is trapped in a local minimum. The primary source of error is inaccurate depth localization, which, due to density stratification, leads to wrong ratios of horizontal and vertical flow velocities ("cross talk"). In the present formulation, the lack of sufficient temporal frequency and spatial resolution makes it difficult to accurately localize flow profiles at depth. We therefore suggest that the most efficient way to discover the global minimum is to perform a probabilistic forward search, involving calculating the misfit associated with a broad range of models (generated, for instance, by a Monte Carlo algorithm) and locating the deepest minimum. Such techniques possess the added advantage of being able to quantify model uncertainty as well as realization noise (data uncertainty).

  9. Accuracy of numerical relativity waveforms from binary neutron star mergers and their comparison with post-Newtonian waveforms

    E-print Network

    Sebastiano Bernuzzi; Marcus Thierfelder; Bernd Bruegmann

    2012-05-22

    We present numerical relativity simulations of nine-orbit equal-mass binary neutron star covering the quasicircular late inspiral and merger. The extracted gravitational waveforms are analyzed for convergence and accuracy. Second order convergence is observed up to contact, i.e. about 3-4 cycles to merger; error estimates can be made up to this point. The uncertainties on the phase and the amplitude are dominated by truncation errors and can be minimized to 0.13 rad and less then 1%, respectively, by using several simulations and extrapolating in resolution. In the latter case finite-radius extraction uncertainties become a source of error of the same order and have to be taken into account. The waveforms are tested against accuracy standards for data analysis. The uncertainties on the waveforms are such that accuracy standards are generically not met for signal-to-noise ratios relevant for detection, except for some best cases using extrapolation from several runs. A detailed analysis of the errors is thus imperative for the use of numerical relativity waveforms from binary neutron stars in quantitative studies. The waveforms are compared with the post-Newtonian Taylor T4 approximants both for point-particle and including the analytically known tidal corrections. The T4 approximants accumulate significant phase differences of 2 rad at contact and 4 rad at merger, underestimating the influence of finite size effects. Tidal signatures in the waveforms are thus important at least during the last six orbits of the merger process.

  10. Accuracy of numerical relativity waveforms from binary neutron star mergers and their comparison with post-Newtonian waveforms

    NASA Astrophysics Data System (ADS)

    Bernuzzi, Sebastiano; Thierfelder, Marcus; Brügmann, Bernd

    2012-05-01

    We present numerical relativity simulations of nine-orbit equal-mass binary neutron star covering the quasicircular late inspiral and merger. The extracted gravitational waveforms are analyzed for convergence and accuracy. Second-order convergence is observed up to contact, i.e. about 3-4 cycles to merger; error estimates can be made up to this point. The uncertainties on the phase and the amplitude are dominated by truncation errors and can be minimized to 0.13 rad and ?1%, respectively, by using several simulations and extrapolating in resolution. In the latter case finite-radius extraction uncertainties become a source of error of the same order and have to be taken into account. The waveforms are tested against accuracy standards for data analysis. The uncertainties on the waveforms are such that accuracy standards are generically not met for signal-to-noise ratios relevant for detection, except for some best cases using extrapolation from several runs. A detailed analysis of the errors is thus imperative for the use of numerical relativity waveforms from binary neutron stars in quantitative studies. The waveforms are compared with the post-Newtonian Taylor T4 approximants both for point-particle and including the analytically known tidal corrections. The T4 approximants accumulate significant phase differences of 2 rad at contact and 4 rad at merger, underestimating the influence of finite-size effects. Tidal signatures in the waveforms are thus important at least during the last six orbits of the merger process.

  11. The role of the FM component in shaping the number of impulses and response latency of inferior collicular neurons of Hipposideros armiger elicited by CF-FM sounds.

    PubMed

    Fu, Zi-Ying; Xu, Na; Wang, Jing; Tang, Jia; Jen, Philip Hung-Sun; Chen, Qi-Cai

    2014-07-25

    Previous studies show that when stimulated with constant frequency-frequency modulated (CF-FM) sounds, the inferior collicular neurons of the leaf-nosed bat, Hipposideros armiger, either discharge impulses only to the CF component (single-on, SO neurons) or to both CF and FM components (double-on, DO neurons). In this study, we specifically determine the role of the FM component in shaping the number of impulses and response latency of these two types of neurons in response to CF-FM sounds. Adding the FM component to the CF sounds significantly decreases the number of impulses of both SO and DO neurons but shortens the response latency of DO neurons in response to the CF component of the CF-FM sounds. The possible neural mechanisms underlying these seemingly paradoxical observations are briefly discussed based on our preliminary intracellular recording studies. Biological relevance of these findings in relation to different phases of bats' hunting is also discussed. PMID:24915297

  12. Effects of the initial chirp and fibre loss on the soliton mechanism of picosecond pulse compression in optical fibres

    SciTech Connect

    Yang Xingyu; Yang Guangqiang [Department of Physics, Inner Mongolia University, Huhhot (China)

    2001-08-31

    The effect of the initial chirp and fibre loss on the efficiency of soliton-effect picosecond pulse compression are analysed by simulating numerically the transmission of picosecond pulse in fibres by the split-step Fourier method. Analysis of changes in the compression factor, the optimum fibre length, and the compression efficiency showed that the initial chirp and fibre loss affect the compression of a picosecond pulse in opposite ways. A further study revealed that an additional properly created initial chirp provides good pulse compression. (nonlinear optical phenomena)

  13. Chirped-pulse manipulated carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs

    SciTech Connect

    Lee, Chao-Kuei, E-mail: chuckcklee@yahoo.com [Department of Photonics, National Sun-Yat-Sen University, Kaohsiung 80400, Taiwan (China); Lin, Yuan-Yao [Department of Electrical Engineering, Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30010, Taiwan (China); Lin, Sung-Hui [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lin, Gong-Ru [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Sec. 4, Taipei 10617, Taiwan (China); Pan, Ci-Ling [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Physics, National Tsing Hwa University, Hsinchu 30010, Taiwan (China)

    2014-04-28

    Chirped pulse controlled carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs are investigated by degenerate pump-probe technique. Varying the chirped condition of excited pulse from negative to positive increases the carrier relaxation time so as to modify the dispersion and reshape current pulse in time domain. The spectral dependence of carrier dynamics is analytically derived and explained by Shockley-Read Hall model. This observation enables the new feasibility of controlling carrier dynamics in ultrafast optical devices via the chirped pulse excitations.

  14. Building Climate Service Capacities in Eastern Africa with CHIRP and GeoCLIM

    NASA Astrophysics Data System (ADS)

    Pedreros, D. H.; Magadzire, T.; Funk, C. C.; Verdin, J. P.; Peterson, P.; Landsfeld, M.; Husak, G. J.

    2013-12-01

    In developing countries there is a great need for capacity building within national and regional climate agencies to develop and analyze historical and real time gridded rainfall datasets. These datasets are of key importance for monitoring climate and agricultural food production at decadal and seasonal time scales, and for informing local decision makers. The Famine Early Warning Systems Network (FEWS NET), working together with the U.S. Geological Survey (USGS) and the Climate Hazards Group (CHG) of the University of California Santa Barbara, has developed an integrated set of data products and tools to support the development of African climate services. The core data product is the Climate Hazards Group Infrared Precipitation (CHIRP) dataset. The CHIRP is a new rainfall dataset resulting from the blending of satellite estimated precipitation with high resolution precipitation climatology. The CHIRP depicts rainfall on five day totals at 5km spatial resolution from 1981 to present. The CHG is developing and deploying a standalone tool - the GeoCLIM - which will allow national and regional meteorological agencies to blend the CHIRP with station observations, run simple crop water balance models, and conduct climatological, trend, and time series analysis. Blending satellite estimates and gauge data helps overcome limited in situ observing networks. Furthermore, the GeoCLIM combines rainfall, soil, and evapotranspiration data with crop hydrological requirements to calculate agricultural water balance, presented as the Water Requirement Satisfaction Index (WRSI). The WRSI is a measurement of the degree in which a crop's hydrological requirements have been satisfied by rainfall. We present the results of a training session for personnel of the East African Intergovernmental Authority on Development Climate Prediction and Applications Center. The two week training program included the use of the GeoCLIM to improve CHIRP using station data, and to calculate and analyze trends in rainfall, WRSI, and drought frequency in the region.

  15. 47 CFR 73.1210 - TV/FM dual-language broadcasting in Puerto Rico.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false TV/FM dual-language broadcasting in Puerto Rico. 73...Stations § 73.1210 TV/FM dual-language broadcasting in Puerto Rico. (a) For the purpose of this section, dual-language broadcasting shall be understood...

  16. 47 CFR 73.1210 - TV/FM dual-language broadcasting in Puerto Rico.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false TV/FM dual-language broadcasting in Puerto Rico. 73...Stations § 73.1210 TV/FM dual-language broadcasting in Puerto Rico. (a) For the purpose of this section, dual-language broadcasting shall be understood...

  17. The U's Facilities Management Department (FM) conducted an internal review of its fire alarm testing

    E-print Network

    Webb, Peter

    Benefits The U's Facilities Management Department (FM) conducted an internal review of its fire alarm testing process in 2009 that resulted in annual savings of approximately $578,000. The fire alarm and repaired by FM employees. The review compared this service model to one where fire alarm services would

  18. FM-dyes as experimental probes for dissecting vesicle trafficking in living plant cells

    Microsoft Academic Search

    S. Bolte; C. Talbot; Y. Boutte; O. Catrice; N. D. Read; B. Satiat-Jeunemaitre

    2004-01-01

    Summary FM-dyes are widely used to study endocytosis, vesicle traffick- ing and organelle organization in living eukaryotic cells. The increasing use of FM-dyes in plant cells has provoked much debate with regard to their suitability as endocytosis markers, which organelles they stain and the precise pathways they follow through the vesicle trafficking network. A primary aim of this article is

  19. 77 FR 24954 - Radio Broadcasting Services; AM or FM Proposals to Change the Community of License

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-26

    ...C., Station KCVM, Facility ID 17227, BPH-20120327ALB, From HUDSON, IA, To EVANSDALE...Station KLYR-FM, Facility ID 22057, BPH-20120208ADK, From CLARKSVILLE, AR...Station WKOV-FM, Facility ID 29691, BPH-20120326ALC, From FRAZEYSBURG,...

  20. Descriptive Study of Noncommercial FM Radio Stations Affiliated with Colleges and Universities.

    ERIC Educational Resources Information Center

    Leidman, Mary Beth; Lamberski, Richard J.

    Designed to establish a framework for current and future documentation of FM radio in institutions of higher education, this study examined the state of noncommercial FM radio stations affiliated with colleges and universities. Topics investigated included: (1) basic descriptions of institutions housing noncommercial radio stations; (2) operating…

  1. A Novel Approach for Finding the Spectrum of Periodically Modulated FM Carriers

    Microsoft Academic Search

    D. Yavuz; U. Inan

    1978-01-01

    A new technique for finding the frequency spectrum of a carrier frequency modulated by a periodic signal is presented. The technique is based on the frequency modulation (FM) equation due to Hess, which in the frequency domain is a double convolution equation. The technique reduces the FM spectrum problem to the solution of a set of linear equations in which

  2. Estimation of earthquake source parameters by the inversion of waveform data: synthetic waveforms

    USGS Publications Warehouse

    Sipkin, S.A.

    1982-01-01

    Two methods are presented for the recovery of a time-dependent moment-tensor source from waveform data. One procedure utilizes multichannel signal-enhancement theory; in the other a multichannel vector-deconvolution approach, developed by Oldenburg (1982) and based on Backus-Gilbert inverse theory, is used. These methods have the advantage of being extremely flexible; both may be used either routinely or as research tools for studying particular earthquakes in detail. Both methods are also robust with respect to small errors in the Green's functions and may be used to refine estimates of source depth by minimizing the misfits to the data. The multichannel vector-deconvolution approach, although it requires more interaction, also allows a trade-off between resolution and accuracy, and complete statistics for the solution are obtained. The procedures have been tested using a number of synthetic body-wave data sets, including point and complex sources, with satisfactory results. ?? 1982.

  3. Where post-Newtonian and numerical-relativity waveforms meet

    E-print Network

    Mark Hannam; Sascha Husa; Jose A. Gonzalez; Ulrich Sperhake; Bernd Bruegmann

    2007-10-16

    We analyze numerical-relativity (NR) waveforms that cover nine orbits (18 gravitational-wave cycles) before merger of an equal-mass system with low eccentricity, with numerical uncertainties of 0.25 radians in the phase and less than 2% in the amplitude; such accuracy allows a direct comparison with post-Newtonian (PN) waveforms. We focus on one of the PN approximants that has been proposed for use in gravitational-wave data analysis, the restricted 3.5PN ``TaylorT1'' waveforms, and compare these with a section of the numerical waveform from the second to the eighth orbit, which is about one and a half orbits before merger. This corresponds to a gravitational-wave frequency range of $M\\omega = 0.0455$ to 0.1. Depending on the method of matching PN and NR waveforms, the accumulated phase disagreement over this frequency range can be within numerical uncertainty. Similar results are found in comparisons with an alternative PN approximant, 3PN ``TaylorT3''. The amplitude disagreement, on the other hand, is around 6%, but roughly constant for all 13 cycles that are compared, suggesting that only 4.5 orbits need be simulated to match PN and NR waves with the same accuracy as is possible with nine orbits. If, however, we model the amplitude up to 2.5PN order, the amplitude disagreement is roughly within numerical uncertainty up to about 11 cycles before merger.

  4. Selection and generation of waveforms for differential mobility spectrometry

    NASA Astrophysics Data System (ADS)

    Krylov, Evgeny V.; Coy, Stephen L.; Vandermey, John; Schneider, Bradley B.; Covey, Thomas R.; Nazarov, Erkinjon G.

    2010-02-01

    Devices based on differential mobility spectrometry (DMS) are used in a number of ways, including applications as ion prefilters for API-MS systems, as detectors or selectors in hybrid instruments (GC-DMS, DMS-IMS), and in standalone systems for chemical detection and identification. DMS ion separation is based on the relative difference between high field and low field ion mobility known as the alpha dependence, and requires the application of an intense asymmetric electric field known as the DMS separation field, typically in the megahertz frequency range. DMS performance depends on the waveform and on the magnitude of this separation field. In this paper, we analyze the relationship between separation waveform and DMS resolution and consider feasible separation field generators. We examine ideal and practical DMS separation field waveforms and discuss separation field generator circuit types and their implementations. To facilitate optimization of the generator designs, we present a set of relations that connect ion alpha dependence to DMS separation fields. Using these relationships we evaluate the DMS separation power of common generator types as a function of their waveform parameters. Optimal waveforms for the major types of DMS separation generators are determined for ions with various alpha dependences. These calculations are validated by comparison with experimental data.

  5. Ocular pressure waveform reflects ventricular bigeminy and aortic insufficiency

    PubMed Central

    Kassem, Jean B; Katz, Steven E; Mahmoud, Ashraf M; Small, Robert H; Raman, Subha V; Roberts, Cynthia J

    2015-01-01

    Ocular pulse amplitude (OPA) is defined as the difference between maximum and minimum intraocular pressure (IOP) during a cardiac cycle. Average values of OPA range from 1 to 4 mmHg. The purpose of this investigation is to determine the source of an irregular IOP waveform with elevated OPA in a 48-year-old male. Ocular pressure waveforms had an unusual shape consistent with early ventricular contraction. With a normal IOP, OPA was 9 mmHg, which is extraordinarily high. The subject was examined by a cardiologist and was determined to be in ventricular bigeminy. In addition, he had bounding carotid pulses and echocardiogram confirmed aortic insufficiency. After replacement of the aortic valve, the bigeminy resolved and the ocular pulse waveform became regular in appearance with an OPA of 1.6–2.0 mmHg. The ocular pressure waveform is a direct reflection of hemodynamics. Evaluating this waveform may provide an additional opportunity for screening subjects for cardiovascular anomalies and arrhythmias. PMID:25686065

  6. A scalable, fast, and multichannel arbitrary waveform generator

    NASA Astrophysics Data System (ADS)

    Baig, M. T.; Johanning, M.; Wiese, A.; Heidbrink, S.; Ziolkowski, M.; Wunderlich, C.

    2013-12-01

    This article reports on the development of a multichannel arbitrary waveform generator that simultaneously generates arbitrary voltage waveforms on 24 independent channels with a dynamic update rate of up to 25 Msps. A real-time execution of a single waveform and/or sequence of multiple waveforms in succession, with a user programmable arbitrary sequence order is provided under the control of a stand-alone sequencer circuit implemented using a field programmable gate array. The device is operated using an internal clock and can be synced to other devices by means of transistor-transistor logic (TTL) pulses. The device can provide up to 24 independent voltages in the range of up to ± 9 V with a dynamic update-rate of up to 25 Msps and a power consumption of less than 35 W. Every channel can be programmed for 16 independent arbitrary waveforms that can be accessed during run time with a minimum switching delay of 160 ns. The device has a low-noise of 250 ?Vrms and provides a stable long-term operation with a drift rate below 10 ?V/min and a maximum deviation less than ± 300 ?Vpp over a period of 2 h.

  7. Selection and generation of waveforms for differential mobility spectrometry

    SciTech Connect

    Krylov, Evgeny V.; Coy, Stephen L.; Nazarov, Erkinjon G. [Sionex Corporation, 8-A Preston Ct., Bedford, Massachusetts 01730 (United States); Vandermey, John; Schneider, Bradley B.; Covey, Thomas R. [MDS Analytical Technologies, 71 Four Valley Drive, Concord, Ontario L4K 4V8 (Canada)

    2010-02-15

    Devices based on differential mobility spectrometry (DMS) are used in a number of ways, including applications as ion prefilters for API-MS systems, as detectors or selectors in hybrid instruments (GC-DMS, DMS-IMS), and in standalone systems for chemical detection and identification. DMS ion separation is based on the relative difference between high field and low field ion mobility known as the alpha dependence, and requires the application of an intense asymmetric electric field known as the DMS separation field, typically in the megahertz frequency range. DMS performance depends on the waveform and on the magnitude of this separation field. In this paper, we analyze the relationship between separation waveform and DMS resolution and consider feasible separation field generators. We examine ideal and practical DMS separation field waveforms and discuss separation field generator circuit types and their implementations. To facilitate optimization of the generator designs, we present a set of relations that connect ion alpha dependence to DMS separation fields. Using these relationships we evaluate the DMS separation power of common generator types as a function of their waveform parameters. Optimal waveforms for the major types of DMS separation generators are determined for ions with various alpha dependences. These calculations are validated by comparison with experimental data.

  8. Chirped-beam two-stage free-electron laser for high-power femtosecond x-ray pulse generation

    NASA Astrophysics Data System (ADS)

    Schroeder, Carl B.; Pellegrini, Claudio; Reiche, Sven; Arthur, John; Emma, Paul

    2002-08-01

    A method for generating femtosecond-duration x-ray pulses with a free-electron laser is presented. This method uses an energy-chirped electron beam propagating through an undulator to produce a frequency-chirped x-ray pulse by self-amplified spontaneous emission. A short temporal pulse is created by use of a monochromator to select a narrow radiation bandwidth. A second undulator is used to amplify the short-duration radiation. The radiation characteristics produced by a chirped-beam two-stage free-electron laser are calculated, and the performance of the chirped-beam two-stage option for the Linac Coherent Light Source is considered. 2002 Optical Society of America

  9. A chirped-pulse Fourier-transform microwave/pulsed uniform flow spectrometer. II. Performance and applications for reaction dynamics

    E-print Network

    Abeysekera, Chamara

    This second paper in a series of two reports on the performance of a new instrument for studying chemical reaction dynamics and kinetics at low temperatures. Our approach employs chirped-pulse Fourier-transform microwave ...

  10. Satellite analog FDMA/FM to digital TDMA conversion

    NASA Technical Reports Server (NTRS)

    Driggers, T.; Nguyen, T.; Kolavennu, V.

    1987-01-01

    The results of a study which investigated design issues regarding the use of analog to digital (A/D) conversion on board a satellite are presented. The need for A/D, and of course D/A as well, conversion arose from a satellite design which required analog FDMA/FM up and down links to/from a digitally modulated intersatellite link. There are also some advantages when one must interconnect a large number of various spot beams which are using analog, and therefore cannot take advantage of SS/TDMA switching among the beams, thus resulting in low fill factors. Various tradeoffs were performed regarding the implementation of on-board A/D processing, including mass, power, and costs. The various technologies which were considered included flash ADCs, surface acoustic wave (SAW) devices, and digital signal processing (DSP) chips. Impact analyses were also performed to determine the effect on ground stations to convert to digital if the A/D approach were not implemented.

  11. Optical performances of the FM JEM-X masks

    NASA Astrophysics Data System (ADS)

    Reglero, V.; Rodrigo, J.; Velasco, T.; Gasent, J. L.; Chato, R.; Alamo, J.; Suso, J.; Blay, P.; Martínez, S.; Doñate, M.; Reina, M.; Sabau, D.; Ruiz-Urien, I.; Santos, I.; Zarauz, J.; Vázquez, J.

    2001-09-01

    The JEM-X Signal Multiplexing Systems are large HURA codes "written" in a pure tungsten plate 0.5 mm thick. 24.247 hexagonal pixels (25% open) are spread over a total area of 535 mm diameter. The tungsten plate is embedded in a mechanical structure formed by a Ti ring, a pretensioning system (Cu-Be) and an exoskeleton structure that provides the required stiffness. The JEM-X masks differ from the SPI and IBIS masks on the absence of a code support structure covering the mask assembly. Open pixels are fully transparent to X-rays. The scope of this paper is to report the optical performances of the FM JEM-X masks defined by uncertainties on the pixel location (centroid) and size coming from the manufacturing and assembly processes. Stability of the code elements under thermoelastic deformations is also discussed. As a general statement, JEM-X Mask optical properties are nearly one order of magnitude better than specified in 1994 during the ESA instrument selection.

  12. A radio-frequency sheath model for complex waveforms

    NASA Astrophysics Data System (ADS)

    Turner, M. M.; Chabert, P.

    2014-04-01

    Plasma sheaths driven by radio-frequency voltages occur in contexts ranging from plasma processing to magnetically confined fusion experiments. An analytical understanding of such sheaths is therefore important, both intrinsically and as an element in more elaborate theoretical structures. Radio-frequency sheaths are commonly excited by highly anharmonic waveforms, but no analytical model exists for this general case. We present a mathematically simple sheath model that is in good agreement with earlier models for single frequency excitation, yet can be solved for arbitrary excitation waveforms. As examples, we discuss dual-frequency and pulse-like waveforms. The model employs the ansatz that the time-averaged electron density is a constant fraction of the ion density. In the cases we discuss, the error introduced by this approximation is small, and in general it can be quantified through an internal consistency condition of the model. This simple and accurate model is likely to have wide application.

  13. The magnetic pumping of plasmas with sawtooth waveforms

    NASA Technical Reports Server (NTRS)

    Borovsky, Joseph E.; Hansen, Paul J.

    1990-01-01

    The pumping of plasmas by sawtooth-waveform magnetic induction variations is studied theoretically and by means of computer simulations. A sawtooth is a cycle waveform that is characterized by a slow increase in the magnetic induction followed by a rapid drop in the induction. Two types of sawtooth pumping are analyzed, and the types classified as to whether or not the first adiabatic invariants of the plasma particles are conserved during the rapid drops in the magnetic induction. When the invariants are conserved, the sawtooth waveforms are found to be less efficient than square waves for pumping plasmas. When the adiabatic invariations are not conserved, the pumping efficiency is found to be a slight improvement over square waves. Both types of pumping are applied to a hypothetical tokamak plasma and it is concluded that neither type of sawtooth pumping is practical for heating magnetically confined fusion plasmas.

  14. A 10 tesla table-top controlled waveform magnet

    NASA Astrophysics Data System (ADS)

    Roy Choudhury, Aditya N.; Venkataraman, V.

    2012-04-01

    Controlled waveform magnets (CWMs) are a class of pulsed magnets whose pulse shape with time can be programmed by the user. With a CWM, the user gains control not only over the magnitude of the field but also over its rate of change. In this work we present a table-top CWM, driven by a capacitor bank, capable of producing virtually any user-shaped magnetic field waveform up to 10 tesla. Insulated gate bipolar transistor chips have been paralleled to form the high current switch and paralleled chips of SiC Schottky diodes form the crowbar diode module. Sample controlled waveforms including flat-tops up to 10 tesla and some triangular magnetic field pulses have been successfully generated for 10-20 ms with a ripple <1%.

  15. A radio-frequency sheath model for complex waveforms

    SciTech Connect

    Turner, M. M. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland); Chabert, P. [Laboratoire de Physique des Plasmas, Centre National de la Recherche Scientifique, Ecole Polytechnique, Université Pierre et Marie Curie, Paris XI, 91128 Palaiseau (France)

    2014-04-21

    Plasma sheaths driven by radio-frequency voltages occur in contexts ranging from plasma processing to magnetically confined fusion experiments. An analytical understanding of such sheaths is therefore important, both intrinsically and as an element in more elaborate theoretical structures. Radio-frequency sheaths are commonly excited by highly anharmonic waveforms, but no analytical model exists for this general case. We present a mathematically simple sheath model that is in good agreement with earlier models for single frequency excitation, yet can be solved for arbitrary excitation waveforms. As examples, we discuss dual-frequency and pulse-like waveforms. The model employs the ansatz that the time-averaged electron density is a constant fraction of the ion density. In the cases we discuss, the error introduced by this approximation is small, and in general it can be quantified through an internal consistency condition of the model. This simple and accurate model is likely to have wide application.

  16. A new and efficient theoretical model to analyze chirped grating distributed feedback lasers

    NASA Astrophysics Data System (ADS)

    Arif, Muhammad

    Threshold conditions of a distributed feedback (DFB) laser with a linearly chirped grating are investigated using a new and efficient method. DFB laser with chirped grating is found to have significant effects on the lasing characteristics. The coupled wave equations for these lasers are derived and solved using a power series method to obtain the threshold condition. A Newton- Raphson routine is used to solve the threshold conditions numerically to obtain threshold gain and lasing wavelengths. To prove the validity of this model, it is applied to both conventional index-coupled and complex- coupled DFB lasers. The threshold gain margins are calculated as functions of the ratio of the gain coupling to index coupling (|?g|/|? n|), and the phase difference between the index and gain gratings. It was found that for coupling coefficient |?|l < 0.9, the laser shows a mode degeneracy at particular values of the ratio |? g|/|?n|, for cleaved facets. We found that at phase differences ?/2 and 3?/2, between the gain and index grating, for an AR-coated complex-coupled laser, the laser becomes multimode and a different mode starts to lase. We also studied the effect of the facet reflectivity (both magnitude and phase) on the gain margin of a complex- coupled DFB laser. Although, the gain margin varies slowly with the magnitude of the facet reflectivity, it shows large variations as a function of the phase. Spatial hole burning was found to be minimum at phase difference n?, n = 0, 1, ... and maximum at phase differences ?/2 and 3?/2. The single mode gain margin of an index-coupled linearly chirped CG-DFB is calculated for different chirping factors and coupling constants. We found that there is clearly an optimum chirping for which the single mode gain margin is maximum. The gain margins were calculated also for different positions of the cavity center. The effect of the facet reflectivities and their phases on the gain margin was investigated. We found the gain margin is maximum and the Spatial Hole Burning (SHB) is minimum for the cavity center at the middle of the laser cavity. Effect of chirping on the threshold gain, gain margin and spatial hole burning (SHB) for different parameters, such as the coupling coefficients, facet reflectivities, etc., of these lasers are studied. Single mode yield of these lasers are calculated and compared with that of a uniform grating DFB laser.

  17. Simultaneous ranging and velocimetry of fast moving targets using oppositely chirped pulses from a mode-locked laser.

    PubMed

    Piracha, Mohammad U; Nguyen, Dat; Ozdur, Ibrahim; Delfyett, Peter J

    2011-06-01

    A lidar system based on the coherent detection of oppositely chirped pulses generated using a 20 MHz mode locked laser and chirped fiber Bragg gratings is presented. Sub millimeter resolution ranging is performed with > 25 dB signal to noise ratio. Simultaneous, range and Doppler velocity measurements are experimentally demonstrated using a target moving at > 330 km/h inside the laboratory. PMID:21716350

  18. Performance limitations of an optical RZ-DPSK transmission system affected by frequency chirp, chromatic dispersion and polarization mode dispersion

    Microsoft Academic Search

    Lazhar Kassa-Baghdouche; Lotfy Mokhtar Simohamed

    2011-01-01

    The performance limitations due to the combined effects of frequency chirp and CD or PMD in a 40 Gbit\\/s optical Return-to-Zero Differential Phase-Shift-Keying (RZDPSK) transmission system are numerically simulated. By means of numerical simulations, we optimize the bandwidths of the optical and electrical receiver’s filters. Then, the impact of the Chirp factor (C) on the Bit Error Rate (BER) performance

  19. Genetic waveform modeling for the crustal structure in Northeast Japan

    NASA Astrophysics Data System (ADS)

    Abdelwahed, Mohamed F.; Zhao, Dapeng

    2014-08-01

    We propose a genetic algorithm (GA) search procedure for waveform modeling of local crustal earthquakes for optimal one-dimensional (1-D) crustal velocity model. Both waveforms and travel-time data are used for the structure determination. The use of travel times in model evaluation improves the waveform modeling performance in the sense of computation speed and accuracy. We applied this method to broadband waveforms of a local crustal earthquake (M 4.2) in Northeast Japan. P-wave velocities of the crustal model are found to be 4.95 ± 0.30, 5.9 ± 0.02, and 6.51 ± 0.20 km/s for a surface layer, upper crust and lower crust, respectively. The surface layer thickness and the Conrad and Moho depths are found to be 3.01 ± 0.8, 17.77 ± 0.4 and 34.59 ± 1.0 km, respectively. For epicentral distances <200 km, our synthetic waveforms match the observed ones generally well. Early arrivals are mainly observed at stations near the Pacific coast in the forearc area having a thinner crust. In contrast, delayed arrivals appear at stations near the volcanic front and back-arc areas where low-velocity anomalies exist due to the effect of the Pacific slab dehydration and the hot upwelling flows in the mantle wedge. In general, our results agree well with the main tectonic setting of the study area, which confirms the reliability of the proposed approach. Despite a 1-D velocity model is too simple to represent the complex crustal structure, it is still required for the conventional routine analysis of seismology, such as earthquake location and source parameter studies. The current approach is considered as a step toward the genetic full waveform modeling for the 3-D velocity model estimation.

  20. Perturbative extraction of gravitational waveforms generated with Numerical Relativity

    E-print Network

    H. Nakano; J. Healy; C. O. Lousto; Y. Zlochower

    2015-03-02

    We derive an analytical expression for extracting the gravitational waveforms at null infinity using the Weyl scalar $\\psi_4$ measured at a finite radius. Our expression is based on a series solution in orders of 1/r to the equations for gravitational perturbations about a spinning black hole. We compute this expression to order $1/r^2$ and include the spin parameter $a$ of the Kerr background. We test the accuracy of this extraction procedure by measuring the waveform for a merging black-hole binary at ten different extraction radii (in the range r/M=75-190) and for three different resolutions in the convergence regime. We find that the extraction formula provides a set of values for the radiated energy and momenta that at finite extraction radii converges towards the expected values with increasing resolution, which is not the case for the `raw' waveform at finite radius. We also examine the phase and amplitude errors in the waveform as a function of observer location and again observe the benefits of using our extraction formula. The leading corrections to the phase are ${\\cal O}(1/r)$ and to the amplitude are ${\\cal O}(1/r^2)$. This method provides a simple and practical way of estimating the waveform at infinity, and may be especially useful for scenarios such as well separated binaries, where the radiation zone is far from the sources, that would otherwise require extended simulation grids in order to extrapolate the `raw' waveform to infinity. Thus this method saves important computational resources and provides an estimate of errors.

  1. Partitioned Waveform Inversion Applied to Eurasia and Northern Africa

    SciTech Connect

    bedle, H; Matzel, E; Flanagan, M

    2006-07-27

    This report summarizes the data analysis achieved during Heather Bedle's eleven-week Technical Scholar internship at Lawrence Livermore National Labs during the early summer 2006. The work completed during this internship resulted in constraints on the crustal and upper mantle S-velocity structure in Northern Africa, the Mediterranean, the Middle East, and Europe, through the fitting of regional waveform data. This data extends current raypath coverage and will be included in a joint inversion along with data from surface wave group velocity measurements, S and P teleseismic arrival time data, and receiver function data to create an improved velocity model of the upper mantle in this region. The tectonic structure of the North African/Mediterranean/Europe/Middle Eastern study region is extremely heterogeneous. This region consists of, among others, stable cratons and platforms such as the West Africa Craton, and Baltica in Northern Europe; oceanic subduction zones throughout the Mediterranean Sea where the African and Eurasian plate collide; regions of continental collision as the Arabian Plate moves northward into the Turkish Plate; and rifting in the Red Sea, separating the Arabian and Nubian shields. With such diverse tectonic structures, many of the waveforms were difficult to fit. This is not unexpected as the waveforms are fit using an averaged structure. In many cases the raypaths encounter several tectonic features, complicating the waveform, and making it hard for the software to converge on a 1D average structure. Overall, the quality of the waveform data was average, with roughly 30% of the waveforms being discarded due to excessive noise that interfered with the frequency ranges of interest. An inversion for the 3D S-velocity structure of this region was also performed following the methodology of Partitioned Waveform Inversion (Nolet, 1990; Van der Lee and Nolet, 1997). The addition of the newly fit waveforms drastically extends the range of the model. The model now extends as far east in Africa to cover Chad and Niger, and reaches south to cover Zambia. The model is also stretched eastward to cover the eastern half of India, and northward to cover the southern portion of Scandinavia.

  2. Optical arbitrary waveform characterization via dual-quadrature spectral interferometry.

    PubMed

    Supradeepa, V R; Leaird, Daniel E; Weiner, Andrew M

    2009-01-01

    We introduce the use of dual-quadrature spectral interferometry for amplitude and phase characterization of 100% duty factor optical arbitrary waveforms generated via spectral line-by-line pulse shaping. We demonstrate this technique for measurement of optical arbitrary waveforms composed of approximately 30 spectral lines from a 10 GHz frequency comb with 1.4 micros data acquisition time at an average power level of 10 microwatts. We then demonstrate coherent spectral phase measurements of pulses strongly dispersed by propagation over 50 km of optical fiber. PMID:19129869

  3. Method for waveform feature extraction from seismic signals

    SciTech Connect

    Chittineni, C.

    1986-12-30

    A method is described for processing seismic signal data comprising: inputting seismic signal data in at least one groups of related trace signals; summing and determining average signals for a selected number of successive traces in each of the at least one groups; determining the correlation matrix for the at least one groups and constructing plural orthonormal basis waveforms; estimating the common signals of the at least one groups of a linear combination of selected ones of the orthonormal basis waveforms; and outputting the common signals as a noise reduced representation of the at least one groups of seismic signal data.

  4. The waveform correlation event detection system global prototype software design

    SciTech Connect

    Beiriger, J.I.; Moore, S.G.; Trujillo, J.R.; Young, C.J.

    1997-12-01

    The WCEDS prototype software system was developed to investigate the usefulness of waveform correlation methods for CTBT monitoring. The WCEDS prototype performs global seismic event detection and has been used in numerous experiments. This report documents the software system design, presenting an overview of the system operation, describing the system functions, tracing the information flow through the system, discussing the software structures, and describing the subsystem services and interactions. The effectiveness of the software design in meeting project objectives is considered, as well as opportunities for code refuse and lessons learned from the development process. The report concludes with recommendations for modifications and additions envisioned for regional waveform-correlation-based detector.

  5. The response of phospholipid-encapsulated microbubbles to chirp-coded excitation: Implications for high-frequency nonlinear imaging

    PubMed Central

    Shekhar, Himanshu; Doyley, Marvin M.

    2013-01-01

    The current excitation strategy for harmonic and subharmonic imaging (HI and SHI) uses short sine-bursts. However, alternate pulsing strategies may be useful for enhancing nonlinear emissions from ultrasound contrast agents. The goal of this study was to corroborate the hypothesis that chirp-coded excitation can improve the performance of high-frequency HI and SHI. A secondary goal was to understand the mechanisms that govern the response of ultrasound contrast agents to chirp-coded and sine-burst excitation schemes. Numerical simulations and acoustic measurements were conducted to evaluate the response of a commercial contrast agent (Targestar-P®) to chirp-coded and sine-burst excitation (10?MHz frequency, peak pressures 290 kPa). The results of the acoustic measurements revealed an improvement in signal-to-noise ratio by 4 to 14?dB, and a two- to threefold reduction in the subharmonic threshold with chirp-coded excitation. Simulations conducted with the Marmottant model suggest that an increase in expansion-dominated radial excursion of microbubbles was the mechanism responsible for the stronger nonlinear response. Additionally, chirp-coded excitation detected the nonlinear response for a wider range of agent concentrations than sine-bursts. Therefore, chirp-coded excitation could be a viable approach for enhancing the performance of HI and SHI. PMID:23654417

  6. 40 CFR Table 34 to Subpart G of... - Fraction Measured (Fm) and Fraction Emitted (Fe) For HAP Compounds in Wastewater Streams

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Fraction Measured (Fm) and Fraction Emitted (Fe) For HAP Compounds in Wastewater Streams...Measured (Fm ) and Fraction Emitted (Fe ) For HAP Compounds in Wastewater Streams Chemical name CAS Number a Fm Fe Acetaldehyde 75070 1.00...

  7. Research progress on a focal plane array ladar system using a laser diode transmitter and FM/cw radar principles

    NASA Astrophysics Data System (ADS)

    Stann, Barry L.; Abou-Auf, Ahmed; Aliberti, Keith; Giza, Mark M.; Ovrebo, Greg; Ruff, William C.; Simon, Deborah R.; Stead, Michael R.

    2002-07-01

    The Army Research Laboratory is developing scannerless ladar systems for smart munition and reconnaissance applications. Here we report on progress attained over the past year related to the construction of a 32x32 pixel ladar. The 32x32 pixel architecture achieves ranging based on a frequency modulation/continuous wave (FM/cw) technique implemented by directly amplitude modulating a near-IR diode laser transmitter with a radio frequency (rf) subcarrier that is linearly frequency modulated. The diode's output is collected and projected to form an illumination field in the downrange image area. The returned signal is focused onto an array of metal-semiconductor-metal (MSM) detectors where it is detected and mixed with a delayed replica of the laser modulation signal that modulates the responsivity of each detector. The output of each detector is an intermediate frequency (IF) signal (a product of the mixing process) whose frequency is proportional to the target range. This IF signal is continuously sampled over each period of the rf modulation. Following this, a N channel signal processor based-on field-programmable gate arrays calculates the discrete Fourier transform over the IF waveform in each pixel to establish the ranges to all the scatterers and their respective amplitudes. Over the past year, we have built one and two-dimensional self-mixing MSM detector arrays at .8 and 1.55 micrometers , designed and built circuit boards for reading data out of a 32x32 pixel array, and designed an N channel FPGA signal processor for high-speed formation of range gates. In this paper we report on the development and performance of these components and the results of system tests conducted in the laboratory.

  8. FM dyes enter via a store-operated calcium channel and modify calcium signaling of cultured astrocytes

    PubMed Central

    Li, Dongdong; Hérault, Karine; Oheim, Martin; Ropert, Nicole

    2009-01-01

    The amphiphilic fluorescent styryl pyridinium dyes FM1-43 and FM4-64 are used to probe activity-dependent synaptic vesicle cycling in neurons. Cultured astrocytes can internalize FM1-43 and FM4-64 inside vesicles but their uptake is insensitive to the elevation of cytosolic calcium (Ca2+) concentration and the underlying mechanism remains unclear. Here we used total internal reflection fluorescence microscopy and pharmacological tools to study the mechanisms of FM4-64 uptake into cultured astrocytes from mouse neocortex. Our data show that: (i) endocytosis is not a major route for FM4-64 uptake into astrocytes; (ii) FM4-64 enters astrocytes through an aqueous pore and strongly affects Ca2+ homeostasis; (iii) partitioning of FM4-64 into the outer leaflet of the plasma membrane results in a facilitation of store-operated Ca2+ entry (SOCE) channel gating; (iv) FM4-64 permeates and competes with Ca2+ for entry through a SOCE channel; (v) intracellular FM4-64 mobilizes Ca2+ from the endoplasmic reticulum stores, conveying a positive feedback to activate SOCE and to sustain dye uptake into astrocytes. Our study demonstrates that FM dyes are not markers of cycling vesicles in astrocytes and calls for a careful interpretation of FM fluorescence. PMID:20007370

  9. FM-selective Networks in Human Auditory Cortex Revealed Using fMRI and Multivariate Pattern Classification

    Microsoft Academic Search

    I-Hui Hsieh; Paul Fillmore; Feng Rong; Gregory Hickok; Kourosh Saberi

    2012-01-01

    Frequency modulation (FM) is an acoustic feature of nearly all complex sounds. Directional FM sweeps are especially pervasive in speech, music, animal vocalizations, and other natural sounds. Although the existence of FM-selective cells in the auditory cortex of animals has been documented, evidence in humans remains equivocal. Here we used multivariate pattern analysis to identify cortical selectivity for direction of

  10. 40 CFR Table 8 to Subpart Ggg of... - Fraction Measured (Fm) for HAP Compounds in Wastewater Streams

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 true Fraction Measured (Fm) for HAP Compounds in Wastewater Streams 8 Table 8 to Subpart GGG of Part 63 Protection...Part 63—Fraction Measured (Fm ) for HAP Compounds in Wastewater Streams Chemical name CAS No. a Fm Acetaldehyde...

  11. 40 CFR Table 8 to Subpart Ggg of... - Fraction Measured (Fm) for HAP Compounds in Wastewater Streams

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Fraction Measured (Fm) for HAP Compounds in Wastewater Streams 8 Table 8 to Subpart GGG of Part 63 Protection...Part 63—Fraction Measured (Fm ) for HAP Compounds in Wastewater Streams Chemical name CAS No. a Fm Acetaldehyde...

  12. 40 CFR Table 8 to Subpart Ggg of... - Fraction Measured (Fm) for HAP Compounds in Wastewater Streams

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2011-07-01 true Fraction Measured (Fm) for HAP Compounds in Wastewater Streams 8 Table 8 to Subpart GGG of Part 63 Protection...Part 63—Fraction Measured (Fm ) for HAP Compounds in Wastewater Streams Chemical name CAS No. a Fm Acetaldehyde...

  13. 40 CFR Table 8 to Subpart Ggg of... - Fraction Measured (Fm) for HAP Compounds in Wastewater Streams

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Fraction Measured (Fm) for HAP Compounds in Wastewater Streams 8 Table 8 to Subpart GGG of Part 63 Protection...Part 63—Fraction Measured (Fm ) for HAP Compounds in Wastewater Streams Chemical name CAS No. a Fm Acetaldehyde...

  14. 40 CFR Table 8 to Subpart Ggg of... - Fraction Measured (Fm) for HAP Compounds in Wastewater Streams

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Fraction Measured (Fm) for HAP Compounds in Wastewater Streams 8 Table 8 to Subpart GGG of Part 63 Protection...Part 63—Fraction Measured (Fm ) for HAP Compounds in Wastewater Streams Chemical name CAS No. a Fm Acetaldehyde...

  15. Low-chirp high-extinction-ratio modulator based on graphene-silicon waveguide.

    PubMed

    Yang, Longzhi; Hu, Ting; Hao, Ran; Qiu, Chen; Xu, Chao; Yu, Hui; Xu, Yang; Jiang, Xiaoqing; Li, Yubo; Yang, Jianyi

    2013-07-15

    We present a hybrid graphene-silicon waveguide, which consists of a lateral slot waveguide with three layers of graphene flakes inside. Through a theoretical analysis, an effective index variation for about 0.05 is found in the waveguide by applying a voltage on the graphene. We designed a Mach-Zehnder modulator based on this waveguide and demonstrated it can process signals nearly chirp-free. The calculation shows that the driving voltage is only 1 V even if the length of the arm is shortened to be 43.54 ?m. An extinction up to 34.7 dB and a minimum chirp parameter of -0.006 are obtained. Its insertion loss is roughly -1.37 dB. This modulator consumes low power and has a small footprint. It can potentially be ultrafast as well as CMOS compatible. PMID:23939097

  16. Ultrashort electron bunch generation by an energy chirping cell attached rf gun

    NASA Astrophysics Data System (ADS)

    Sakaue, K.; Koshiba, Y.; Mizugaki, M.; Washio, M.; Takatomi, T.; Urakawa, J.; Kuroda, R.

    2014-02-01

    We present a new design for a rf electron gun to be used in ultrashort (˜1 ps) electron bunch generation. Using both simulation and measurement we evaluated the principle of this new type rf gun and were able to confirm an ultrashort bunch generation. During simulation, a bunch length of less than 100 fs(rms) with a 100 pC/bunch charge was confirmed at the optimum operating condition. The principle is to produce a linearly distributed longitudinal phase space by using an attached output cell specially designed for energy chirping. Such phase space distribution can be rotated by the velocity difference in the bunch. We already fabricated an energy chirping cell attached rf gun and successfully observed 0.2 THz coherent synchrotron radiation, which corresponds to less than 500 fs bunch. Such an electron gun can be used as a compact THz light source and a new electron injector with an ultrashort bunch.

  17. FEMTOSECOND X-RAY PULSES FROM A FREQUENCY CHIRPED SASE FEL.

    SciTech Connect

    KRINSKY,S.HUANG,Z.

    2004-01-07

    We discuss the temporal and spectral properties of self-amplified spontaneous emission (SASE) utilizing an energy-chirped electron beam. A short temporal pulse is generated by using a monochromator to select a narrow radiation bandwidth from the frequency chirped SASE. For the filtered radiation, the minimum pulse length is limited by the intrinsic SASE bandwidth, while the number of modes and the energy fluctuation can be controlled through the monochromator bandwidth. Two cases are considered: (1) placing the monochromator at the end of a single long undulator; (2) placing the monochromator after an initial undulator and amplifying the short-duration output in a second undulator. We analyze these cases and show that tens of femtosecond x-ray pulses may be generated for the linac coherent light source.

  18. Making ultracold molecules in a two-color pump-dump photoassociation scheme using chirped pulses

    SciTech Connect

    Koch, Christiane P. [Laboratoire Aime Cotton, CNRS, Bat. 505, Campus d'Orsay, 91405 Orsay Cedex (France); Department of Physical Chemistry and Fritz Haber Research Center, Hebrew University, Jerusalem 91904 (Israel); Luc-Koenig, Eliane; Masnou-Seeuws, Francoise [Laboratoire Aime Cotton, CNRS, Bat. 505, Campus d'Orsay, 91405 Orsay Cedex (France)

    2006-03-15

    This theoretical paper investigates the formation of ground state molecules from ultracold cesium atoms in a two-color scheme. Following previous work on photoassociation with chirped picosecond pulses [Luc-Koenig et al., Phys. Rev. A, 70, 033414 (2004)], we investigate stabilization by a second (dump) pulse. By appropriately choosing the dump pulse parameters and time delay with respect to the photoassociation pulse, we show that a large number of deeply bound molecules are created in the ground triplet state. We discuss (i) broad-bandwidth dump pulses which maximize the probability to form molecules while creating a broad vibrational distribution as well as (ii) narrow-bandwidth pulses populating a single vibrational ground state level, bound by 113 cm{sup -1}. The use of chirped pulses makes the two-color scheme robust, simple, and efficient.

  19. Impact of modulator chirp in 100 Gbps class optical discrete multi-tone transmission system

    NASA Astrophysics Data System (ADS)

    Nishihara, Masato; Tanaka, Toshiki; Takahara, Tomoo; Li, Lei; Tao, Zhenning; Rasmussen, Jens C.

    2012-12-01

    Discrete multi-tone (DMT) technology is an attractive modulation technique for short reach optical transmission system. One of the main factors that limit the performance of the 1.5-?m band DMT system is the interplay between the chromatic dispersion of the transmission fiber and the chirp characteristic of the transmitter. We experimentally measured and compared the chirp characteristics of various modulator configurations, which are lithium-niobate Mach-Zehnder modulator, directly modulated laser, and electro-absorption modulator, by the frequency discriminator method using MZ interferometer. We also measured and compared the transmission characteristics of the transmitters using above-mentioned modulators and discuss the suitable transmitter configuration for DMT technology.

  20. Self-injected semiconductor distributed feedback lasers for frequency chirp stabilization.

    PubMed

    Kechaou, Khalil; Grillot, Frédéric; Provost, Jean-Guy; Thedrez, Bruno; Erasme, Didier

    2012-11-01

    It is well known that semiconductor distributed feedback lasers (DFB) are key devices for optical communications. However direct modulation applications are limited by the frequency chirp induced by current modulation. We demonstrate that a proper external control laser operation leads to chirp-to-power ratio (CPR) stabilization over a wide range of modulation frequencies as compared to the free-running case. Under experimentally selected optical feedback conditions, the CPR decreases significantly in the adiabatic regime from about 650 MHz/mW in the solitary case down to 65 MHz/mW. Experimental results are also confirmed by numerical investigations based on the transfer matrix method. Simulations point out the possible optimization of the CPR in the adiabatic regime by considering a judicious cavity design in conjunction with a proper external control. These results demonstrate important routes for improving the transmission performance in optical telecommunication systems. PMID:23187422

  1. Periodic compression of chirped femtosecond pulses in silicon waveguides under fourth-order dispersion

    NASA Astrophysics Data System (ADS)

    Mandeng Mandeng, Lucien; Ibraid Fewo, Serge; Tchawoua, Clément; Crépin Kofané, Timoléon

    2014-08-01

    We report the analysis of the compression mechanism for chirped femtosecond pulses in silicon-on-insulator waveguides under the effect of fourth-order dispersion (FOD) using the modified variational approach that involves Rayleigh's dissipation function (RDF). Our results show that the nonlinear compression in these waveguides is input pulse dependent. Moreover, this study leads to a nearly periodic-like dynamic induced by the interplay between self-phase modulation and FOD in a normal group-velocity dispersion. In addition, when large values of the initial chirp and absorption coefficients present in these waveguides are considered, the compression mechanism is completely destroyed, with the observation of at least one pulse amplification over a short distance of propagation prior to pulse broadening.

  2. All optical quantum storage based on spatial chirp of the control field

    E-print Network

    Xiwen Zhang; Alexey Kalachev; Olga Kocharovskaya

    2014-10-21

    We suggest an all-optical quantum memory scheme which is based on the off-resonant Raman interaction of a signal quantum field and a strong control field in a three-level atomic medium in the case, when the control field has a spatially varying frequency across the beam, called a spatial chirp. We show that the effect of such a spatial chirp is analogous to the effect of a controllable reversible inhomogeneous broadening (CRIB) of the atomic transition used in the gradient echo memory (GEM) scheme. However, the proposed scheme does not require temporal modulation of the control field or the atomic levels, and can be realized without additional electric or magnetic fields. It means that materials demonstrating neither linear Stark nor Zeeman effects can be used and/or materials which are placed in specific external fields remain undisturbed.

  3. Characterization of strong fiber Bragg gratings using an applied thermal chirp and iterative algorithm.

    PubMed

    Miller, Gary A; Peele, John R; Askins, Charles G; Cranch, Geoffrey A

    2011-12-20

    Coupling coefficients of various grating types and strengths are calculated from measurements of the complex reflectivity using an applied thermal chirp and optical frequency domain reflectometry (OFDR). The complex reflectivity is then utilized by a layer peeling algorithm to determine the coupling coefficient of the thermally chirped grating. A guess of the temperature profile enables the coupling coefficient of the unchirped grating to be estimated. An iterative algorithm is then used to converge on the exact coupling coefficient, employing an error minimization method applied to the reflectivity spectra. This technique removes the need for a reference grating while preserving the spatial resolution obtained with the initial OFDR measurement. Successful reconstruction of gratings with integrated |?|L ~ 9.0 are demonstrated with a spatial resolution of less than 100 ?m. PMID:22193191

  4. Forensic Application of FM-CW and Pulse Radar

    SciTech Connect

    S. K. Koppenjan; R. S. Freeland; M. L. Miller; R. E. Yoder

    2003-01-01

    Ground-penetrating radar (GPR) technology has supplied vital assistance in criminal investigations. However, law enforcement personnel desire further developments such that the technology is rapidly deployable, and that it provides both a simple user interface and sophisticated target identification. To assist in the development of target identification algorithms, our efforts involve gathering background GPR data for the various site conditions and circumstances that often typify clandestine burials. For this study, forensic anthropologists established shallow-grave plots at The University of Tennessee Anthropological Research Facility (ARF) that are specific to GPR research. These plots contain donated human cadavers lying in various configurations and depths, surrounded by assorted construction material and backfill debris. We scanned the plots using two GPR technologies: (1) a multi-frequency synthetic-aperture FM-CW radar (200-700 MHz) (GPR-X) developed by the U.S. Department of Energy's (DOE) Special Technologies Laboratory (STL), Bechtel Nevada (Koppenjan et al., 2000), and (2) a commercial pulse radar (SIR-20) manufactured by Geophysical Survey Systems, Inc. (400 and 900 MHz)(GSSI). The sweep-frequency data show the large biological mass decomposing within the torso as encircled ''hot spots.'' The 400-MHz pulse radar exhibit major horizontal reflectors above the body, with shadow reflectors (horizontal multiples) occurring beneath the body at 60 cm depth. The 400-MHz antenna was able to discern the grave walls and folded tarp covering the lower body. Under these moist, clay-rich conditions, the 900-MHz antenna was able to penetrate slightly beyond 30 cm beneath the concrete layer. However, neither system was able to penetrate beyond a one meter depth in the moist, clay-rich soil (fine, mixed, thermic Typic Paleudalf). Example scans from each system are provided, along with a discussion of the survey protocol and general performance.

  5. Chirp control of an electroabsorption modulator to be used for regeneration and wavelength conversion at 40 gbit\\/s in all-optical networking

    Microsoft Academic Search

    M. Y. Jamro; J. M. Senior

    2005-01-01

    Chirp control to produce low or negative values of chirp at the output of an electroabsorption modulator (EAM) is an important mechanism for reducing the signal degradation due to chromatic dispersion in high-speed transmission over standard single-mode fibre. An analytical model for the chirp performance of an EAM capable of optical regeneration and simultaneous wavelength conversion operating at 40 Gbit\\/s

  6. Deexcitation of high-Rydberg-state atoms with a chirped train of half-cycle pulses

    Microsoft Academic Search

    T. Kopyciuk; R. Parzynski

    2007-01-01

    Encouraged by the experiments on production of antihydrogen atoms in high Rydberg states we have calculated the effect of deexcitation towards lower states by a chirped train of identical unidirectional half-cycle pulses. The calculations exploit both the one-dimensional and impulse approximations providing convenient analytical formulas for the Rydberg-to-Rydberg transition amplitudes. The calculated deexcitation is shown in terms of the mean

  7. 1.5 ?m MQW-DFB laser diode with low chirp and low threshold current

    Microsoft Academic Search

    K. Mizuguchi; N. Yoshida; T. Kimura; A. Takemoto; Y. Ohkura; M. Tsugami; T. Murotani

    1989-01-01

    1.55-?m band InGaAs-InGaAsP multiple-quantum-well distributed feedback laser diodes have been successfully fabricated by metalorganic chemical vapor deposition. The threshold current is as low as 9 mA, and the slope efficiency is 0.2 mW\\/mA. A very low chirp of 3 Å at 2 Gbit\\/s NRZ modulation is obtained

  8. Tunable optical delay line in SOI implemented with step chirped Bragg gratings and serial grating arrays

    NASA Astrophysics Data System (ADS)

    Spasojevic, Mina; Chen, Lawrence R.

    2013-10-01

    Tunable optical delay devices have numerous applications in optical communications [1] and have been successfully implemented using slow light elements and fiber or waveguide gratings. There has been considerable interest in siliconon- insulator (SOI) as a technology platform for compact integration of optical signal processing systems. SOI-based delay lines have been realized using coupled ring resonators [2], photonic crystals [3], and various Bragg grating-based configurations including single or coupled chirped sidewall gratings [4,5] as well as tapered rib waveguide gratings [6]. By linearly chirping the period in sidewall gratings, relatively small delays (a few ps) over a bandwidth of tens of nm were demonstrated [4]; with tapered waveguides, significantly larger delays (300-500 ps) were obtained, albeit over a narrower bandwidth (< 2 nm) [6]. On the other hand, some signal processing applications may require large delays (e.g., tens to hundreds of ps) over large bandwidths (several to tens of nm). Several designs have been proposed to meet these requirements, e.g., a step-chirped rib waveguide grating providing 50 ps delay over 15 nm [7] or complementary apodized sidewall gratings providing up to 275 ps over 3 nm [8], however, they have not been realized experimentally. In this paper, we demonstrate discretely tunable optical delay lines that provide tens of ps delay (up to 65 ps) in steps of 15-32 ps over bandwidths of several tens of nm (35-70 nm). The devices are fabricated on SOI using electron beam lithography and implemented through two different approaches: serial sidewall Bragg grating arrays and the step-chirped sidewall Bragg gratings.

  9. Theory and design of a photoinjector-driven chirped pulse free-electron maser

    Microsoft Academic Search

    Gregory P. Le Sage; Helena X. C. Feng; Lisa L. Laurent; F. V. Hartemann; S. N. Fochs; M. D. Perry; G. A. Westenskow; J. P. Heritage

    1996-01-01

    An overview of the design parameters of a compact high-gradient high-luminosity X-band (8.568 GHz) photoinjector is followed by a more detailed description of each of its major subsystems: X-band RF gun, GHz repetition rate synchronously modelocked AlGaAs quantum well laser oscillator, and eight-pass Ti:Al2O3 chirped pulse laser amplifier. The photoinjector uses a high quantum efficiency (~5%) Cs2Te photocathode, and is

  10. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    PubMed

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth. PMID:20548342

  11. Microjoule pulse energy from a chirped-pulse Ti:sapphire oscillator with cavity-dumping

    Microsoft Academic Search

    M. Siegel; N. Pfullmann; G. Palmer; S. Rausch; T. Binhammer; U. Morgner

    2009-01-01

    In this paper, we report for the first time to our knowledge on a chirped-pulse Ti:sapphire laser oscillator with acousto-optical cavity-dumping that reaches pulse energies in excess of 1 muJ at a repetition rate of 1 MHz and with a spectral width supporting pulse durations below 80 fs. After the laser, a CW-pumped, cryogenically cooled amplifier is used to further

  12. 160-gb\\/s adaptive dispersion equalization using an asynchronous dispersion-induced chirp monitor

    Microsoft Academic Search

    Tetsuro Inui; Tetsuro Komukai; Kunihiko Mori; Toshio Morioka

    2005-01-01

    This paper describes an adaptive dispersion equalizer (ADE) that uses an asynchronous dispersion-induced chirp monitor and the detailed study of the first demonstration of 160-Gb\\/s adaptive dispersion equalization. The device successfully equalized the dispersion change over a 40°C temperature range (from 5°C to 45°C) and the dispersion slope of an 80-km dispersion-shifted fiber (DSF). The ADE will enhance the feasibility

  13. Two and Three Beam Pumped Optical Parametric Amplifier of Chirped Pulses

    NASA Astrophysics Data System (ADS)

    Ališauskas, S.; Butkus, R.; Pyragait?, V.; Smilgevi?ius, V.; Stabinis, A.; Piskarskas, A.

    2010-04-01

    We present two and three beam pumped optical parametric amplifier of broadband chirped pulses. The seed pulses from Ti:sapphire oscillator were stretched and amplified in a non-collinear geometry pumping with up to three beams derived from independent laser amplifiers. The signal with ˜90 nm bandwidth was amplified up to 0.72 mJ. The conversion efficiency dependence on intersection angles of pump beams is also revealed.

  14. Ultrahigh contrast from a frequency-doubled chirped-pulse-amplification beamline.

    PubMed

    Hillier, David; Danson, Colin; Duffield, Stuart; Egan, David; Elsmere, Stephen; Girling, Mark; Harvey, Ewan; Hopps, Nicholas; Norman, Michael; Parker, Stefan; Treadwell, Paul; Winter, David; Bett, Thomas

    2013-06-20

    This paper describes frequency-doubled operation of a high-energy chirped-pulse-amplification beamline. Efficient type-I second-harmonic generation was achieved using a 3 mm thick 320 mm aperture KDP crystal. Shots were fired at a range of energies achieving more than 100 J in a subpicosecond, 527 nm laser pulse with a power contrast of 10(14). PMID:23842168

  15. New stretcher scheme for a parametric amplifier of chirped pulses with frequency conversion

    SciTech Connect

    Freidman, Gennadii I; Yakovlev, I V [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2007-02-28

    The properties of hybrid prism-grating dispersion systems are studied. The scheme of a prism-grating stretcher matched to a standard compressor in the phase dispersion up to the fourth order inclusive is developed for a petawatt laser complex based on the optical parametric chirped-pulse amplification. The stretcher was used to obtain the {approx}200-TW peak power of laser radiation. (control of laser radiation parameters)

  16. Spectral broadening and self-compression of negatively chirped visible femtosecond pulses in fused silica

    SciTech Connect

    Aristov, A I; Grudtsyn, Ya V; Mikheev, L D; Polivin, A V; Stepanov, S G; Trofimov, V A; Yalovoi, V I

    2012-12-31

    This paper describes a new effect: spectral broadening and self-compression of negatively chirped visible femtosecond pulses as a result of nonlinear interaction of large-aperture beams with fused silica. We assume that the likely mechanism of the observed spectral broadening is the combined effect of self-phase modulation and four-wave mixing. (special issue devoted to the 90th anniversary of n.g. basov)

  17. Chirped lasers dispersion spectroscopy implemented with single- and dual-sideband electro-optical modulators.

    PubMed

    Nikodem, Michal; Plant, Genevieve; Wang, Zhenxing; Prucnal, Paul; Wysocki, Gerard

    2013-06-17

    We report new approaches for signal generation in Chirped Laser Dispersion Spectroscopy (CLaDS). Two optical arrangements based on electro-optical modulators significantly reduce CLaDS system complexity and enable optimum performance when applied to detection of GHz-wide molecular transitions. Proof-of-principle experiments in the near-infrared spectral range are presented and potential strategies for application in the mid-infrared are discussed. PMID:23787653

  18. Mapping attenuation beneath North America using waveform cross-correlation and cluster analysis

    E-print Network

    Shearer, Peter

    Mapping attenuation beneath North America using waveform cross- correlation and cluster analysis America using waveform cross-correlation and cluster analysis, and obtain images of the laterally varying anelastic structure of the upper mantle. Cluster analysis improves attenuation measurements

  19. The effects of electric and magnetic fields on the current spin polarization and magnetoresistance in a ferromagnetic/organic semiconductor/ferromagnetic (FM/OSC/FM) system

    NASA Astrophysics Data System (ADS)

    Wang, Yu-Mei; Ren, Jun-Feng; Yuan, Xiao-Bo; Dou, Zhao-Tao; Hu, Gui-Chao

    2012-10-01

    From experimental results of spin polarized injection and transport in organic semiconductors (OSCs), we theoretically study the current spin polarization and magnetoresistance under an electric and a magnetic field in a ferromagnetic/organic semiconductor/ferromagnetic (FM/OSC/FM) sandwich structure according to the spin drift-diffusion theory and Ohm's law. From the calculations, it is found that the interfacial current spin polarization is enhanced by several orders of magnitude through tuning the magnetic and electric fields by taking into account the specific characteristics of OSC. Furthermore, the effects of the electric and magnetic fields on the magnetoresistance are also discussed in the sandwich structure.

  20. Highly depth-resolved chirped pulse photothermal radar for bone diagnostics

    NASA Astrophysics Data System (ADS)

    Kaiplavil, Sreekumar; Mandelis, Andreas

    2011-07-01

    A novel chirped pulse photothermal (PT) radiometric radar with improved sensitivity over the conventional harmonically modulated thermal-wave radar technique and alternative pulsed laser photothermal radiometry is introduced for the diagnosis of biological samples, especially bones with tissue and skin overlayers. The constraints imposed by the laser safety (maximum permissible exposure) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (a few mm below the skin surface). A theoretical approach for improvement of signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal signal and making use of the photothermal radiometric nonlinearity has been introduced and verified by comparing the SNR of four distinct excitation wave forms (sine-wave, square-wave, constant-width and constant duty-cycle pulses) for chirping the pump laser, under constant exposure energy. At low frequencies fixed-pulsewidth chirps of large peak power were found to be superior to all other equal-energy modalities, with an SNR improvement up to two orders of magnitude. Distinct thickness-dependent characteristic delay times in a goat bone were obtained, establishing an active depth resolution range of ˜2.8 mm in a layered skin-fat-bone structure, a favorable result compared to the maximum reported pulsed photothermal radiometric depth resolution <1 mm in turbid biological media.

  1. Wideband-adjustable reflection-suppressed rejection filters using chirped and tilted fiber gratings.

    PubMed

    Liu, Fu; Guo, Tuan; Wu, Chuang; Guan, Bai-Ou; Lu, Chao; Tam, Hwa-Yaw; Albert, Jacques

    2014-10-01

    Wideband-adjustable band-rejection filters based on chirped and tilted fiber Bragg gratings (CTFBG) are proposed and experimentally demonstrated. The flexible chirp-rate and wide tilt-angle provide the gratings with broadband filtering functions over a large range of bandwidths (from 10 nm to 150 nm), together with a low insertion loss (less than 1 dB) and a negligible back-reflection (lower than -20 dB). The slope profile of CTFBG in transmission can be easily tailored by adjusting the tilt angle, grating irradiation time and chirp rate-grating factor, and it is insensitive to the polarization state of the input light, as well as to temperature, axial strain and surrounding refractive index. Furthermore, by coating the CTFBG with a suitable polymer (whose refractive index is close to that of the cladding glass), the cladding modes no longer form weakly discrete resonances and leave a smoothly varying attenuation spectrum for high-quality band-rejection filters, edge filters and gain equalizers. PMID:25322019

  2. Trends in ultrashort and ultrahigh power laser pulses based on optical parametric chirped pulse amplification

    NASA Astrophysics Data System (ADS)

    Xu, Lu; Yu, Liang-Hong; Chu, Yu-Xi; Gan, Ze-Biao; Liang, Xiao-Yan; Li, Ru-Xin; Xu, Zhi-Zhan

    2015-01-01

    Since the proof-of-principle demonstration of optical parametric amplification to efficiently amplify chirped laser pulses in 1992, optical parametric chirped pulse amplification (OPCPA) became the most promising method for the amplification of broadband optical pulses. In the meantime, we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers. The output power and pulse duration of these systems have ranged from a few gigawatts to hundreds of terawatts with a potential of tens of petawatts power level. Meanwhile, the output pulse duration based on optical parametric amplification has entered the range of few-optical-cycle field. In this paper, we overview the basic principles, trends in development, and current state of the ultrashort and laser systems based on OPCPA, respectively. Project supported by the National Natural Science Foundation of China (Grant Nos. 61378030 and 11127901), the National Basic Research Program of China(Grant No. 2011CB808101), and the International S&T Cooperation Program of China (Grant No. 2011DFA11300).

  3. FY07 LDRD Final Report Precision, Split Beam, Chirped-Pulse, Seed Laser Technology

    SciTech Connect

    Dawson, J W; Messerly, M J; Phan, H H; Crane, J K; Beach, R J; Siders, C W; Barty, C J

    2009-11-12

    The goal of this LDRD ER was to develop a robust and reliable technology to seed high-energy laser systems with chirped pulses that can be amplified to kilo-Joule energies and recompressed to sub-picosecond pulse widths creating extremely high peak powers suitable for petawatt class physics experiments. This LDRD project focused on the development of optical fiber laser technologies compatible with the current long pulse National Ignition Facility (NIF) seed laser. New technologies developed under this project include, high stability mode-locked fiber lasers, fiber based techniques for reduction of compressed pulse pedestals and prepulses, new compact stretchers based on chirped fiber Bragg gratings (CFBGs), new techniques for manipulation of chirped pulses prior to amplification and new high-energy fiber amplifiers. This project was highly successful and met virtually all of its goals. The National Ignition Campaign has found the results of this work to be very helpful. The LDRD developed system is being employed in experiments to engineer the Advanced Radiographic Capability (ARC) front end and the fully engineered version of the ARC Front End will employ much of the technology and techniques developed here.

  4. Helium in chirped laser fields as a time-asymmetric atomic switch

    SciTech Connect

    Kaprálová-Ž?ánská, Petra Ruth, E-mail: kapralova@jh-inst.cas.cz [Department of Radiation and Chemical Physics, Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8 (Czech Republic); J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8 (Czech Republic); Moiseyev, Nimrod, E-mail: nimrod@tx.technion.ac.il [Schulich Faculty of Chemistry and Faculty of Physics, Technion – Israel Institute of Technology, Haifa 32000 (Israel)

    2014-07-07

    Tuning the laser parameters exceptional points in the spectrum of the dressed laser helium atom are obtained. The weak linearly polarized laser couples the ground state and the doubly excited P-states of helium. We show here that for specific chirped laser pulses that encircle an exceptional point one can get the time-asymmetric phenomenon, where for a negative chirped laser pulse the ground state is transformed into the doubly excited auto-ionization state, while for a positive chirped laser pulse the resonance state is not populated and the neutral helium atoms remains in the ground state as the laser pulse is turned off. Moreover, we show that the results are very sensitive to the closed contour we choose. This time-asymmetric state exchange phenomenon can be considered as a time-asymmetric atomic switch. The optimal time-asymmetric switch is obtained when the closed loop that encircles the exceptional point is large, while for the smallest loops, the time-asymmetric phenomenon does not take place. A systematic way for studying the effect of the chosen closed contour that encircles the exceptional point on the time-asymmetric phenomenon is proposed.

  5. Temporal compression and shaping of chirped biphotons using Fresnel-inspired binary phase shaping

    NASA Astrophysics Data System (ADS)

    Li, Baihong; Xu, Yonggang; Zhu, Haifei; Lin, Fukun; Li, Yongfang

    2015-02-01

    Chirped biphotons generated via spontaneous parametric down-conversion in chirped quasi-phase-matched nonlinear crystals have ultrabroadband frequency spectra, while their correlation times are not ultranarrow, due to the nonlinear frequency dependence of the phase factor. Based on the idea of Fresnel zone lenses, we propose a Fresnel-inspired binary phase-shaping scheme for tailoring broadband biphoton spectra. By applying binary phase masks to the biphoton spectrum, a Fresnel zone lens was produced in the frequency domain, compressing the broadband temporal wave packets of the chirped biphotons to the Fourier-transform limit due to the effective removal of the quadratic phase. Furthermore, biphoton correlation trains can also be generated by properly shaping the biphoton spectrum with this scheme. This provides a method for biphoton compression and shaping, which avoids the length dependence and the impact of higher-order dispersion in a dispersive medium by using the phase compensation method. Our results could prove useful in quantum metrology, lithography, and coding of entangled photons.

  6. Imaging sediments in the deep, rough terrain at the Mid-Atlantic Ridge using AUV Sentry's CHIRP sub-bottom profiler

    NASA Astrophysics Data System (ADS)

    Yoerger, D.; Parnell-Turner, R. E.; Smith, D. K.; Cann, J. R.; Schouten, H.; Dick, H. J.; Kurras, G.; Duester, A.; Billings, A.; Kelley, S.

    2013-12-01

    AUV Sentry carries an Edgetch 2200M sub-bottom profiler, which uses a CHIRP signal (a broadband, swept waveform) in the 4 - 24 kHz range. The sub-bottom profiles obtained from AUV Sentry provide a new and exciting look at the detailed morphology of the sediments covering the deep seafloor. We obtained sub-bottom profiles on 11 Sentry dives during RV Knorr Cruise 210-05 in May-June 2013. Our study region was centered at 16.5N on the flanks of the Mid-Atlantic Ridge (MAR). Sentry flew at ~60 m above the seafloor traversing terrain that included features over 1 km in relief. The data were processed at sea using MBSystem and SeismicUnix software packages. Processing consisted of the following steps: data conversion from Edgetech jsf to SEGY format; bandpass filter to remove frequencies associated with other instruments on the vehicle; static correction according to vehicle depth; and depth conversion using a constant (water) velocity of 1500 m/s. The resulting images are excellent in quality. Sedimentary layers were identified above the acoustic basement, with thicknesses ranging from tens of centimeters to 4-5 m. Preliminary interpretation shows no evidence for reflections beneath the sediment - basement interface. We have used the high-resolution sub-bottom profiles to estimate sedimentation rate at this section of the MAR, and in combination with the other high-resolution products from Sentry we have been able to argue that some of the long-lived faults observed in the region are still active.

  7. Correcting low-frequency phase distortion in electroglottograph waveforms.

    PubMed

    Rothenberg, Martin

    2002-03-01

    Dynamic high-pass filtering with a -3 dB frequency that is a factor of ten or more below the voice fundamental frequency has a negligible effect on the amplitudes of the Fourier components of an EGG waveform. However, such a filter can significantly distort the waveform due to distortion in the phase or time alignment of these Fourier components. Such high-pass filtering can be introduced purposefully to stabilize the waveform by attenuating low-frequency noise, or may be an undesired effect of using an amplification or data acquisition system designed for acoustic signals. For a given voice fundamental frequency, the amount of distortion depends greatly on the order or attenuation characteristics of the filter and on the type of EGG waveform. Both a high-order filter and a breathy voice tend to increase the amount of distortion. If the characteristics of the high-pass filter are known, there are a number of digital filter techniques that can be used to reduce the phase distortion. However, it is shown that a relatively simple analogue network can also be used to obtain a correction that suffices for most applications. If the precise characteristics of the filter are not known, the response to a square wave can be used to adjust the compensator parameters for an optimal correction. PMID:12002884

  8. Virtual MIMO radar using OFDM-CDM waveforms

    Microsoft Academic Search

    S. Zazo; B. Bejar; J. Grajal

    2008-01-01

    This paper addresses a new perspective on the exploitation of diversity resembling recent seminal proposals with multiple antennas known as MIMO radar. Our focus pursues similar advantages as spatial MIMO systems but intending to achieve the desired resistance over fading or\\/and SNR increase without relying on multiple antennas. We design an OFDM-CDM waveform well inspired in modern communications systems that

  9. Optimal control theory with arbitrary superpositions of waveforms

    E-print Network

    Selina Meister; Jürgen T. Stockburger; Rebecca Schmidt; Joachim Ankerhold

    2014-11-20

    Standard optimal control methods perform optimization in the time domain. However, many experimental settings demand the expression of the control signal as a superposition of given waveforms, a case that cannot easily be accommodated using time-local constraints. Previous approaches [1,2] have circumvented this difficulty by performing optimization in a parameter space, using the chain rule to make a connection to the time domain. In this paper, we present an extension to Optimal Control Theory which allows gradient-based optimization for superpositions of arbitrary waveforms directly in a time-domain subspace. Its key is the use of the Moore-Penrose pseudoinverse as an efficient means of transforming between a time-local and waveform-based descriptions. To illustrate this optimization technique, we study the parametrically driven harmonic oscillator as model system and reduce its energy, considering both Hamiltonian dynamics and stochastic dynamics under the influence of a thermal reservoir. We demonstrate the viability and efficiency of the method for these test cases and find significant advantages in the case of waveforms which do not form an orthogonal basis.

  10. Notched spectrum: from probing waveforms to receive filters

    NASA Astrophysics Data System (ADS)

    Jiang, Yi; Gianelli, Christopher D.

    2013-05-01

    The increasing demand for wireless data services and communications is expanding the frequency footprint of both civilian and military wireless networks, and hence encroaches upon spectrum traditionally reserved for radar systems. To maximize spectral efficiency, it is desirable for a modern radar system to use waveforms with the ability to fit into tightly controlled spectral regions, which requires the formation of nulls with required notching levels on prescribed frequency stop-bands. Additionally, the waveform should posses a low peak-to-average ratio (PAR), and have good auto-correlation performance. In this work, we propose a novel method for the design of such a waveform using alternating convex optimization. The core module of the proposed algorithm is a fast Fourier transform, which makes the algorithm quite efficient and can handle waveform designs with up to 105 samples. Moreover, our algorithm can achieve a flexible tradeoff between PAR and reduced pass band ripple. A simple application in synthetic aperture radar is considered to highlight the performance of the design algorithm.

  11. Inferring Environmental Information from SHOALS-1000 Waveform Data

    NASA Astrophysics Data System (ADS)

    Tuell, G. H.; Park, J.

    2003-12-01

    In the SHOALS-1000 bathymetric laser system, water depth measurements are computed by time differencing the surface and bottom detections in multiple channels of the returned waveform data. The mechanics of this process are well understood and have been implemented in earlier generations of SHOALS technology (Guenther, 2000). Recently, there has been an increase in interest in using these waveforms to infer other environmental parameters. For example, (Wang and Philpot, 2003) have shown that the shape of the bottom return can be used to discriminate between land and water in very shallow water; (Elston, 2003) has shown that shape analysis can be used for benthic classification; and (Lee and Tuell, 2003) have shown that pseudoreflectance (an approximation of bottom reflectance at the laser wavelength) can also be used for classification. These are important innovations in that they contribute to our ability to conduct data fusion studies using decision-level algorithms as demonstrated by (Park, 2002). But other innovations are possible. Because the SHOALS waveforms are digitized at 1-ns intervals, it may soon be possible to use them to infer vertical structure of the water column. Here, we describe the data structure and availability of SHOALS waveform data and show pseudoreflectance imagery generated from recent data acquired at the South Florida Testing Facility.

  12. A compact, multichannel, and low noise arbitrary waveform generator

    SciTech Connect

    Govorkov, S. [Sema Systems, 302-5553 16th ave., Delta, British Columbia V4M 2H7 (Canada)] [Sema Systems, 302-5553 16th ave., Delta, British Columbia V4M 2H7 (Canada); Ivanov, B. I. [Leibniz-Institute of Photonic Technology, PO Box 100239, D-07702 Jena (Germany) [Leibniz-Institute of Photonic Technology, PO Box 100239, D-07702 Jena (Germany); Novosibirsk State Technical University, K.Marx-Ave. 20, Novosibirsk 630092 (Russian Federation); Il'ichev, E.; Meyer, H.-G. [Leibniz-Institute of Photonic Technology, PO Box 100239, D-07702 Jena (Germany)] [Leibniz-Institute of Photonic Technology, PO Box 100239, D-07702 Jena (Germany)

    2014-05-15

    A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 ? SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.

  13. Optimized Waveform Relaxation Solution of Electromagnetic and Circuit Problems

    E-print Network

    Gander, Martin J.

    a method for the parallel solution of time domain combined ElectroMagetic (EM) and circuit problems. The EM1 Optimized Waveform Relaxation Solution of Electromagnetic and Circuit Problems Martin J. Gander-- New algorithms are needed to solve electromagnetic problems using today's widely available parallel

  14. Waveform and packet structure of lion roars W. Baumjohann1

    E-print Network

    Paris-Sud XI, Université de

    Waveform and packet structure of lion roars W. Baumjohann1 , R. A. Treumann1 , E. Georgescu1Y2 , G-called lion roars, typically seen by the Equator-S magnetometer at the bottom of the magnetic troughs the ®rst search-coil magnetometer observa- tions of what they called lion roars inside magnetic troughs

  15. Deconvolution of sea state parameters from altimeter waveforms

    NASA Technical Reports Server (NTRS)

    Rodriguez, Ernesto; Chapman, Bruce; Chi, Chong-Yung; Liu, Eric

    1987-01-01

    The paper reports on an on-going effort at the JPL to estimate the accuracy of ocean state parameters which have been obtained from the specular point probability density function (pdf) of the ocean surface. This pdf is obtained by the deconvolution of the return waveform of oceanographic altimeters such as Seasat, Geosat, or Topex.

  16. A marked point process for modeling lidar waveforms.

    PubMed

    Mallet, Clément; Lafarge, Florent; Roux, Michel; Soergel, Uwe; Bretar, Frédéric; Heipke, Christian

    2010-12-01

    Lidar waveforms are 1-D signals representing a train of echoes caused by reflections at different targets. Modeling these echoes with the appropriate parametric function is useful to retrieve information about the physical characteristics of the targets. This paper presents a new probabilistic model based upon a marked point process which reconstructs the echoes from recorded discrete waveforms as a sequence of parametric curves. Such an approach allows to fit each mode of a waveform with the most suitable function and to deal with both, symmetric and asymmetric, echoes. The model takes into account a data term, which measures the coherence between the models and the waveforms, and a regularization term, which introduces prior knowledge on the reconstructed signal. The exploration of the associated configuration space is performed by a reversible jump Markov chain Monte Carlo (RJMCMC) sampler coupled with simulated annealing. Experiments with different kinds of lidar signals, especially from urban scenes, show the high potential of the proposed approach. To further demonstrate the advantages of the suggested method, actual laser scans are classified and the results are reported. PMID:20550992

  17. Consistency of Post-Newtonian Waveforms with Numerical Relativity

    NASA Technical Reports Server (NTRS)

    Baker, John G.; vanMeter, James R.; McWilliams, Sean T.; Centrella, Joan; Kelly, Bernard J.

    2007-01-01

    General relativity predicts the gravitational radiation signatures of mergers of compact binaries,such as coalescing binary black hole systems. Derivations of waveform predictions for such systems are required for optimal scientific analysis of observational gravitational wave data, and have so far been achieved primarily with the aid of the post-Newtonian (PN) approximation. The quaIity of this treatment is unclear, however, for the important late inspiral portion. We derive late-inspiral wave forms via a complementary approach, direct numerical simulation of Einstein's equations, which has recently matured sufficiently for such applications. We compare waveform phasing from simulations covering the last approximately 14 cycles of gravitational radiation from an equal-mass binary system of nonspinning black holes with corresponding 3PN and 3.5PN waveforms. We find phasing agreement consistent with internal error estimates based in either approach, at the level of one radian over approximately 10 cycles. The result suggests that PN waveforms for this system are effective roughly until the system reaches its last stable orbit just prior to the final merger.

  18. CLUTTER DOPPLER RANGE DEPENDENCY IN ORTHOGONAL-WAVEFORM-DIVERSITY-PROCESSING

    E-print Network

    Adve, Raviraj

    the benefits of combining frequency diversity and space time adaptive processing for distributed aperture represents an initial effort in the area of bistatic and multistatic space-time adap- tive processing (STAPCLUTTER DOPPLER RANGE DEPENDENCY IN ORTHOGONAL-WAVEFORM-DIVERSITY-PROCESSING FOR DISTRIBUTED

  19. Repeatability of electromyographic waveforms during the Naeryo Chagi in taekwondo

    Microsoft Academic Search

    Nickos Aggeloussis; Vassilis Gourgoulis; Maria Sertsou; Erasmia Giannakou; George Mavromatis

    2007-01-01

    The purpose of the research was to study the repeatability of electromyographic (EMG) waveforms of major lower limb muscles during the naeryo chagi (axe kick) in taekwondo. Six male and female athletes, aged between 20 and 24 years served as volunteers. All participants were black belt holders and per- formed the naeryo chagi with their right leg. The electromyog- raphic

  20. Charge-injection waveforms for iridium oxide (AIROF) microelectrodes

    Microsoft Academic Search

    S. F. Cogan; P. R. Troyk; J. Ehrlich; T. D. Plante; D. B. McCreery; L. Bullara

    2003-01-01

    The charge-injection limits of activated iridium oxide (AIROF) microelectrodes subjected to charge-balanced biphasic current pulsing are investigated as a function of anodic bias and asymmetry in the cathodic and anodic pulse widths. The use of asymmetric waveforms, in which the charge balancing anodic phase is delivered at a lower current density and longer pulse width, permits the use of anodic