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Sample records for pulse compression workshop

  1. International magnetic pulse compression workshop: (Proceedings)

    Energy Technology Data Exchange (ETDEWEB)

    Kirbie, H.C.; Newton, M.A.; Siemens, P.D.

    1991-04-01

    A few individuals have tried to broaden the understanding of specific and salient pulsed-power topics. One such attempt is this documentation of a workshop on magnetic switching as it applies primarily to pulse compression (power transformation), affording a truly international perspective by its participants under the initiative and leadership of Hugh Kirbie and Mark Newton of the Lawrence Livermore National Laboratory (LLNL) and supported by other interested organizations. During the course of the Workshop at Granlibakken, a great deal of information was amassed and a keen insight into both the problems and opportunities as to the use of this switching approach was developed. The segmented workshop format proved ideal for identifying key aspects affecting optimum performance in a variety of applications. Individual groups of experts addressed network and system modeling, magnetic materials, power conditioning, core cooling and dielectrics, and finally circuits and application. At the end, they came together to consolidate their input and formulate the workshop's conclusions, identifying roadblocks or suggesting research projects, particularly as they apply to magnetic switching's trump card--its high-average-power-handling capability (at least on a burst-mode basis). The workshop was especially productive both in the quality and quantity of information transfer in an environment conducive to a free and open exchange of ideas. We will not delve into the organization proper of this meeting, rather we wish to commend to the interested reader this volume, which provides the definitive and most up-to-date compilation on the subject of magnetic pulse compression from underlying principles to current state of the art as well as the prognosis for the future of magnetic pulse compression as a consensus of the workshop's organizers and participants.

  2. Excimer Laser Pulse Compress With Pulse Feedback

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>To attain a shorter laser pulse, a compressing technique called pulse feedback was developed from the saturation gain switch applied to the amplification in a discharge pumping excimer laser cavity. It can

  3. Space and Earth Science Data Compression Workshop

    Science.gov (United States)

    Tilton, James C. (Editor)

    1991-01-01

    The workshop explored opportunities for data compression to enhance the collection and analysis of space and Earth science data. The focus was on scientists' data requirements, as well as constraints imposed by the data collection, transmission, distribution, and archival systems. The workshop consisted of several invited papers; two described information systems for space and Earth science data, four depicted analysis scenarios for extracting information of scientific interest from data collected by Earth orbiting and deep space platforms, and a final one was a general tutorial on image data compression.

  4. Binary-phase compression of stretched pulses

    Science.gov (United States)

    Lozovoy, Vadim V.; Nairat, Muath; Dantus, Marcos

    2017-10-01

    Pulse stretching and compression are essential for the energy scale-up of ultrafast lasers. Here, we consider a radical approach using spectral binary phases, containing only two values (0 and π) for stretching and compressing laser pulses. We numerically explore different strategies and present results for pulse compression of factors up to a million back to the transform limit and experimentally obtain results for pulse compression of a factor of one hundred, in close agreement with numerical calculations. Imperfections resulting from binary-phase compression are addressed by considering cross-polarized wave generation filtering, and show that this approach leads to compressed pulses with contrast ratios greater than ten orders of magnitude. This new concept of binary-phase stretching and compression, if implemented in a multi-layer optic, could eliminate the need for traditional pulse stretchers and more importantly expensive compressors.

  5. Pulse compression and prepulse suppression apparatus

    Science.gov (United States)

    Dane, C.B.; Hackel, L.A.; George, E.V.; Miller, J.L.; Krupke, W.F.

    1993-11-09

    A pulse compression and prepulse suppression apparatus (10) for time compressing the output of a laser (14). A pump pulse (46) is separated from a seed pulse (48) by a first polarized beam splitter (20) according to the orientation of a half wave plate (18). The seed pulse (48) is directed into an SBS oscillator (44) by two plane mirrors (22, 26) and a corner mirror (24), the corner mirror (24) being movable to adjust timing. The pump pulse (46) is directed into an SBS amplifier 34 wherein SBS occurs. The seed pulse (48), having been propagated from the SBS oscillator (44), is then directed through the SBS amplifier (34) wherein it sweeps the energy of the pump pulse (46) out of the SBS amplifier (34) and is simultaneously compressed, and the time compressed pump pulse (46) is emitted as a pulse output (52). A second polarized beam splitter (38) directs any undepleted pump pulse 58 away from the SBS oscillator (44).

  6. Combined Industry, Space and Earth Science Data Compression Workshop

    Science.gov (United States)

    Kiely, Aaron B. (Editor); Renner, Robert L. (Editor)

    1996-01-01

    The sixth annual Space and Earth Science Data Compression Workshop and the third annual Data Compression Industry Workshop were held as a single combined workshop. The workshop was held April 4, 1996 in Snowbird, Utah in conjunction with the 1996 IEEE Data Compression Conference, which was held at the same location March 31 - April 3, 1996. The Space and Earth Science Data Compression sessions seek to explore opportunities for data compression to enhance the collection, analysis, and retrieval of space and earth science data. Of particular interest is data compression research that is integrated into, or has the potential to be integrated into, a particular space or earth science data information system. Preference is given to data compression research that takes into account the scien- tist's data requirements, and the constraints imposed by the data collection, transmission, distribution and archival systems.

  7. Pulse compression by use of deformable mirrors.

    Science.gov (United States)

    Zeek, E; Maginnis, K; Backus, S; Russek, U; Murnane, M; Mourou, G; Kapteyn, H; Vdovin, G

    1999-04-01

    An electrostatically deformable, gold-coated, silicon nitride membrane mirror was used as a phase modulator to compress pulses from 92 to 15 fs. Both an iterative genetic algorithm and single-step dispersion compensation based on frequency-resolved optical gating calibration of the mirror were used to compress pulses to within 10% of the transform limit. Frequency-resolved optical gating was used to characterize the pulses and to test the range of the deformable-mirror-based compressor.

  8. Method for Generating a Compressed Optical Pulse

    DEFF Research Database (Denmark)

    2015-01-01

    There is presented a method of for generating a compressed optical pulse (112) comprising emitting from a wavelength tunable microcavity laser system (102), comprising an optical cavity (104) with a mechanically adjustable cavity length (L), a primary optical pulse (111) having a primary temporal...... width (Tl) while adjusting the optical cavity length (L) so that said primary optical pulse comprises temporally separated photons of different wavelengths, and transmitting said pulse through a dispersive medium (114), so as to generate a compressed optical pulse (112) with a secondary temporal width...

  9. Cascaded Soliton Compression of Energetic Femtosecond Pulses at 1030 nm

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin

    2012-01-01

    We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved.......We discuss soliton compression with cascaded second-harmonic generation of energetic femtosecond pulses at 1030 nm. We discuss problems encountered with soliton compression of long pulses and show that sub-10 fs compressed pulses can be achieved....

  10. Pulse Compression Technique of Radio Fuze

    Institute of Scientific and Technical Information of China (English)

    HU Xiu-juan; DENG Jia-hao; SANG Hui-ping

    2006-01-01

    The advantages of using phase-coded pulse compression technique for radio fuze systems are evaluated. With building mathematical models a matched filter has be en implemented successfully. Various simulations for pulse compression waveform coding were done to evaluate the performance of fuze system under noisy environment. The results of the simulation and the data analysis show that the phase-coded pulse compression gets a good result in the signal identification of the radio fuze with matched filter. Simultaneously, a suitable sidelobe suppression filter is established by simulation, the suppressed sidelobe level is acceptable to radio fuze application.

  11. Evolution Strategies for Laser Pulse Compression

    NARCIS (Netherlands)

    Monmarché, Nicolas; Fanciulli, Riccardo; Willmes, Lars; Talbi, El-Ghazali; Savolainen, Janne; Collet, Pierre; Schoenauer, Marc; van der Walle, P.; Lutton, Evelyne; Back, Thomas; Herek, Jennifer Lynn

    2008-01-01

    This study describes first steps taken to bring evolutionary optimization technology from computer simulations to real world experimentation in physics laboratories. The approach taken considers a well understood Laser Pulse Compression problem accessible both to simulation and laboratory experiment

  12. RF pulse compression for future linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.

    1995-05-01

    Future (nonsuperconducting) linear colliders will require very high values of peak rf power per meter of accelerating structure. The role of rf pulse compression in producing this power is examined within the context of overall rf system design for three future colliders at energies of 1.0--1.5 TeV, 5 TeV and 25 TeV. In order keep the average AC input power and the length of the accelerator within reasonable limits, a collider in the 1.0--1.5 TeV energy range will probably be built at an x-band rf frequency, and will require a peak power on the order of 150--200 MW per meter of accelerating structure. A 5 TeV collider at 34 GHz with a reasonable length (35 km) and AC input power (225 MW) would require about 550 MW per meter of structure. Two-beam accelerators can achieve peak powers of this order by applying dc pulse compression techniques (induction linac modules) to produce the drive beam. Klystron-driven colliders achieve high peak power by a combination of dc pulse compression (modulators) and rf pulse compression, with about the same overall rf system efficiency (30--40%) as a two-beam collider. A high gain (6.8) three-stage binary pulse compression system with high efficiency (80%) is described, which (compared to a SLED-11 system) can be used to reduce the klystron peak power by about a factor of two, or alternately, to cut the number of klystrons in half for a 1.0--1.5 TeV x-band collider. For a 5 TeV klystron-driven collider, a high gain, high efficiency rf pulse compression system is essential.

  13. Binary rf pulse compression experiment at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Lavine, T.L.; Spalek, G.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Wilson, P.B.

    1990-06-01

    Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range, to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at low-power (1-kW) and high-power (15-MW) input levels in initial testing with a TWT and a klystron. Rf pulses initially 770 nsec long have been compressed to 60 nsec. Peak power gains of 1.8 per stage, and 5.5 for three stages, have been measured. This corresponds to a peak power compression efficiency of about 90% per stage, or about 70% for three stages, consistent with the individual component losses. The principle of operation of a binary pulse compressor (BPC) is described in detail elsewhere. We recently have implemented and operated at SLAC a high-power (high-vacuum) three-stage X-band BPC. First results from the high-power three-stage BPC experiment are reported here.

  14. Proceedings of Pulsed Magnet Design and Measurement Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Shaftan, T.; Heese, R.; Ozaki,S.

    2010-01-19

    The goals of the Workshop are to assess the design of pulsed system at the NSLS-II and establish mitigation strategies for critical issues during development. The focus of the Workshop is on resolving questions related to the set-up of the pulsed magnet laboratory, on measuring the pulsed magnet's current waveforms and fields, and on achieving tight tolerances on the magnet's alignment and field quality.

  15. High reflection mirrors for pulse compression gratings.

    Science.gov (United States)

    Palmier, S; Neauport, J; Baclet, N; Lavastre, E; Dupuy, G

    2009-10-26

    We report an experimental investigation of high reflection mirrors used to fabricate gratings for pulse compression application at the wavelength of 1.053microm. Two kinds of mirrors are studied: the mixed Metal MultiLayer Dielectric (MMLD) mirrors which combine a gold metal layer with some e-beam evaporated dielectric bilayers on the top and the standard e-beam evaporated MultiLayer Dielectric (MLD) mirrors. Various samples were manufactured, damage tested at a pulse duration of 500fs. Damage sites were subsequently observed by means of Nomarski microscopy and white light interferometer microscopy. The comparison of the results evidences that if MMLD design can offer damage performances rather similar to MLD design, it also exhibits lower stresses; being thus an optimal mirror substrate for a pulse compression grating operating under vacuum.

  16. 76 FR 4338 - Research and Development Strategies for Compressed & Cryo-Compressed Hydrogen Storage Workshops

    Science.gov (United States)

    2011-01-25

    ... Research and Development Strategies for Compressed & Cryo- Compressed Hydrogen Storage Workshops AGENCY... Development Manager, Fuel Cell Technology Program, EE-2H, 1000 Independence Ave., SE., Washington, DC 20585... 14th will be to identify strategies to lower the cost of high pressure hydrogen storage systems...

  17. The OMV Data Compression System Science Data Compression Workshop

    Science.gov (United States)

    Lewis, Garton H., Jr.

    1989-01-01

    The Video Compression Unit (VCU), Video Reconstruction Unit (VRU), theory and algorithms for implementation of Orbital Maneuvering Vehicle (OMV) source coding, docking mode, channel coding, error containment, and video tape preprocessed space imagery are presented in viewgraph format.

  18. 1994 Science Information Management and Data Compression Workshop

    Science.gov (United States)

    Tilton, James C. (Editor)

    1994-01-01

    This document is the proceedings from the 'Science Information Management and Data Compression Workshop,' which was held on September 26-27, 1994, at the NASA Goddard Space Flight Center, Greenbelt, Maryland. The Workshop explored promising computational approaches for handling the collection, ingestion, archival and retrieval of large quantities of data in future Earth and space science missions. It consisted of eleven presentations covering a range of information management and data compression approaches that are being or have been integrated into actual or prototypical Earth or space science data information systems, or that hold promise for such an application. The workshop was organized by James C. Tilton and Robert F. Cromp of the NASA Goddard Space Flight Center.

  19. The 1995 Science Information Management and Data Compression Workshop

    Science.gov (United States)

    Tilton, James C. (Editor)

    1995-01-01

    This document is the proceedings from the 'Science Information Management and Data Compression Workshop,' which was held on October 26-27, 1995, at the NASA Goddard Space Flight Center, Greenbelt, Maryland. The Workshop explored promising computational approaches for handling the collection, ingestion, archival, and retrieval of large quantities of data in future Earth and space science missions. It consisted of fourteen presentations covering a range of information management and data compression approaches that are being or have been integrated into actual or prototypical Earth or space science data information systems, or that hold promise for such an application. The Workshop was organized by James C. Tilton and Robert F. Cromp of the NASA Goddard Space Flight Center.

  20. Control of high power pulse extracted from the maximally compressed pulse in a nonlinear optical fiber

    CERN Document Server

    Yang, Guangye; Jia, Suotang; Mihalache, Dumitru

    2013-01-01

    We address the possibility to control high power pulses extracted from the maximally compressed pulse in a nonlinear optical fiber by adjusting the initial excitation parameters. The numerical results show that the power, location and splitting order number of the maximally compressed pulse and the transmission features of high power pulses extracted from the maximally compressed pulse can be manipulated through adjusting the modulation amplitude, width, and phase of the initial Gaussian-type perturbation pulse on a continuous wave background.

  1. Saturable inductor and transformer structures for magnetic pulse compression

    Science.gov (United States)

    Birx, Daniel L.; Reginato, Louis L.

    1990-01-01

    Saturable inductor and transformer for magnetic compression of an electronic pulse, using a continuous electrical conductor looped several times around a tightly packed core of saturable inductor material.

  2. Pulse-compression ghost imaging lidar via coherent detection

    CERN Document Server

    Deng, Chenjin; Han, Shensheng

    2016-01-01

    Ghost imaging (GI) lidar, as a novel remote sensing technique,has been receiving increasing interest in recent years. By combining pulse-compression technique and coherent detection with GI, we propose a new lidar system called pulse-compression GI lidar. Our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar can obtain the target's spatial intensity distribution, range and moving velocity. Compared with conventional pulsed GI lidar system, pulse-compression GI lidar, without decreasing the range resolution, is easy to obtain high single pulse energy with the use of a long pulse, and the mechanism of coherent detection can eliminate the influence of the stray light, which can dramatically improve the detection sensitivity and detection range.

  3. Pulse-compression ghost imaging lidar via coherent detection.

    Science.gov (United States)

    Deng, Chenjin; Gong, Wenlin; Han, Shensheng

    2016-11-14

    Ghost imaging (GI) lidar, as a novel remote sensing technique, has been receiving increasing interest in recent years. By combining pulse-compression technique and coherent detection with GI, we propose a new lidar system called pulse-compression GI lidar. Our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar can obtain the target's spatial intensity distribution, range and moving velocity. Compared with conventional pulsed GI lidar system, pulse-compression GI lidar, without decreasing the range resolution, is easy to obtain high single pulse energy with the use of a long pulse, and the mechanism of coherent detection can eliminate the influence of the stray light, which is helpful to improve the detection sensitivity and detection range.

  4. Workshop on Fundamental Science using Pulsed Power

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, Alan [Univ. of Texas, Austin, TX (United States)

    2016-02-20

    The project objective was to fund travel to a workshop organized by the Institute for High Energy Density Science (IHEDS) at the University of Texas at Austin. In so doing the intent was to a) Grow the national academic High Energy Density Science (HEDS) community, b) Expand high impact, discovery driven fundamental HEDS, and c) Facilitate user-oriented research

  5. Observation of soliton pulse compression in photonic crystal waveguides

    CERN Document Server

    Colman, P; Combrié, S; Sagnes, I; Wong, C W; De Rossi, A

    2010-01-01

    We demonstrate soliton-effect pulse compression in mm-long photonic crystal waveguides resulting from strong anomalous dispersion and self-phase modulation. Compression from 3ps to 580fs, at low pulse energies(~10pJ), is measured via autocorrelation.

  6. Time-lens based optical packet pulse compression and retiming

    DEFF Research Database (Denmark)

    Laguardia Areal, Janaina; Hu, Hao; Palushani, Evarist

    2010-01-01

    compression, as well. The overall design is: (1) Pulses are converted from NRZ to RZ; (2) pulses are synchronized, retimed and further compressed at the specially designed time-lens; and (3) with adequate optical delays, frames from different input interfaces are added, with a simple optical coupler...

  7. Fibonacci-like photonic structure for femtosecond pulse compression.

    Science.gov (United States)

    Makarava, L N; Nazarov, M M; Ozheredov, I A; Shkurinov, A P; Smirnov, A G; Zhukovsky, S V

    2007-03-01

    The compression of femtosecond laser pulses by linear quasiperiodic and periodic photonic multilayer structures is studied both experimentally and theoretically. We compare the compression performance of a Fibonacci and a periodic structure with similar total thickness and the same number of layers, and find the performance to be higher in the Fibonacci case, as predicted by numerical simulation. This compression enhancement takes place due to the larger group velocity dispersion at a defect resonance of the transmission spectrum of the Fibonacci structure. We demonstrate that the Fibonacci structure with the thickness of only 2.8 microm can compress a phase-modulated laser pulse by up to 30%. The possibility for compression of laser pulses with different characteristics in a single multilayer is explored. The operation of the compressor in the reflection regime has been modeled, and we show numerically that the reflected laser pulse is subjected to real compression: not only does its duration decrease but also its amplitude rises.

  8. Compressive spectrum sensing of radar pulses based on photonic techniques.

    Science.gov (United States)

    Guo, Qiang; Liang, Yunhua; Chen, Minghua; Chen, Hongwei; Xie, Shizhong

    2015-02-23

    We present a photonic-assisted compressive sampling (CS) system which can acquire about 10(6) radar pulses per second spanning from 500 MHz to 5 GHz with a 520-MHz analog-to-digital converter (ADC). A rectangular pulse, a linear frequency modulated (LFM) pulse and a pulse stream is respectively reconstructed faithfully through this system with a sliding window-based recovery algorithm, demonstrating the feasibility of the proposed photonic-assisted CS system in spectral estimation for radar pulses.

  9. All-optical three-dimensional electron pulse compression

    CERN Document Server

    Wong, Liang Jie; Rohwer, Timm; Gedik, Nuh; Johnson, Steven G

    2014-01-01

    We propose an all-optical, three-dimensional electron pulse compression scheme in which Hermite-Gaussian optical modes are used to fashion a three-dimensional optical trap in the electron pulse's rest frame. We show that the correct choices of optical incidence angles are necessary for optimal compression. We obtain analytical expressions for the net impulse imparted by Hermite-Gaussian free-space modes of arbitrary order. Although we focus on electrons, our theory applies to any charged particle and any particle with non-zero polarizability in the Rayleigh regime. We verify our theory numerically using exact solutions to Maxwell's equations for first-order Hermite-Gaussian beams, demonstrating single-electron pulse compression factors of $>10^{2}$ in both longitudinal and transverse dimensions with experimentally realizable optical pulses. The proposed scheme is useful in ultrafast electron imaging for both single- and multi-electron pulse compression, and as a means of circumventing temporal distortions in ...

  10. Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique

    Science.gov (United States)

    Li, Lihua; Coon, Michael; McLinden, Matthew

    2013-01-01

    Pulse compression has been widely used in radars so that low-power, long RF pulses can be transmitted, rather than a highpower short pulse. Pulse compression radars offer a number of advantages over high-power short pulsed radars, such as no need of high-power RF circuitry, no need of high-voltage electronics, compact size and light weight, better range resolution, and better reliability. However, range sidelobe associated with pulse compression has prevented the use of this technique on spaceborne radars since surface returns detected by range sidelobes may mask the returns from a nearby weak cloud or precipitation particles. Research on adaptive pulse compression was carried out utilizing a field-programmable gate array (FPGA) waveform generation board and a radar transceiver simulator. The results have shown significant improvements in pulse compression sidelobe performance. Microwave and millimeter-wave radars present many technological challenges for Earth and planetary science applications. The traditional tube-based radars use high-voltage power supply/modulators and high-power RF transmitters; therefore, these radars usually have large size, heavy weight, and reliability issues for space and airborne platforms. Pulse compression technology has provided a path toward meeting many of these radar challenges. Recent advances in digital waveform generation, digital receivers, and solid-state power amplifiers have opened a new era for applying pulse compression to the development of compact and high-performance airborne and spaceborne remote sensing radars. The primary objective of this innovative effort is to develop and test a new pulse compression technique to achieve ultrarange sidelobes so that this technique can be applied to spaceborne, airborne, and ground-based remote sensing radars to meet future science requirements. By using digital waveform generation, digital receiver, and solid-state power amplifier technologies, this improved pulse compression

  11. Pulse chirp increasing pulse compression followed by positive resonant radiation in fibers

    CERN Document Server

    McLenaghan, Joanna

    2016-01-01

    Pulse self-compression followed by the generation of resonant radiation is a well known phenomenon in non-linear optics. Resonant radiation is important as it allows for efficient and tunable wavelength conversion. We vary the chirp of the initial pulse and find in simulations and experiments that a small positive chirp enhances the pulse compression and strongly increases the generation of resonant radiation. This result corroborates previously published simulation results indicating an improved degree of pulse compression for a small positive chirp [1]. It also demonstrates how pulse evolution can be studied without cutting back the fiber.

  12. Pulse Compression And Raman Amplification In Optical Fibres

    Science.gov (United States)

    Byron, Kevin C.

    1988-06-01

    Experimental and theoretical investigations on Raman amplification in fibres have been carried out and simultaneous amplification and pulse compression observed. With a fibre design optimised for amplification high gain may be obtained at practical pump power levels.

  13. Divided-pulse nonlinear amplification and simultaneous compression

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Qiang; Zhang, Qingshan; Sun, Tingting; Chen, Jie; Wang, Yuqing; Guo, Zhengru; Yang, Kangwen [Shanghai Key Laboratory of Modern Optical System, and Engineering Research Center of Optical Instrument and System, Ministry of Education, School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Guo, Zhanhua [Shanghai Langyan Optoelectronic Science and Technology Co., LTD, Shanghai 200433 (China); Zeng, Heping, E-mail: hpzeng@phy.ecnu.edu.cn [Shanghai Key Laboratory of Modern Optical System, and Engineering Research Center of Optical Instrument and System, Ministry of Education, School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

    2015-03-09

    We report on a fiber laser system delivering 122 fs pulse duration and 600 mW average power at 1560 nm by the interplay between divided pulse amplification and nonlinear pulse compression. A small-core double-clad erbium-doped fiber with anomalous dispersion carries out the pulse amplification and simultaneously compresses the laser pulses such that a separate compressor is no longer necessary. A numeric simulation reveals the existence of an optimum fiber length for producing transform-limited pulses. Furthermore, frequency doubling to 780 nm with 240 mW average power and 98 fs pulse duration is achieved by using a periodically poled lithium niobate crystal at room temperature.

  14. Development of ultra-short high voltage pulse technology using magnetic pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Byung Heon; Kim, S. G.; Nam, S. M.; Lee, B. C.; Lee, S. M.; Jeong, Y. U.; Cho, S. O.; Jin, J. T.; Choi, H. L

    1998-01-01

    The control circuit for high voltage switches, the saturable inductor for magnetic assist, and the magnetic pulse compression circuit were designed, constructed, and tested. The core materials of saturable inductors in magnetic pulse compression circuit were amorphous metal and ferrite and total compression stages were 3. By the test, in high repetition rate, high pulse compression were certified. As a result of this test, it became possible to increase life-time of thyratrons and to replace thyratrons by solid-state semiconductor switches. (author). 16 refs., 16 tabs.

  15. Using electric fields for pulse compression and group velocity control

    CERN Document Server

    Li, Qian; Thuresson, Axel; Rippe, Lars; Kröll, Stefan

    2016-01-01

    In this article, we experimentally demonstrate a new way of controlling the group velocity of an optical pulse by using a combination of spectral hole burning, slow light effect and linear Stark effect in a rare-earth-ion-doped crystal. The group velocity can be changed continuously by a factor of 20 without significant pulse distortion or absorption of the pulse energy. With a similar technique, an optical pulse can also be compressed in time. Theoretical simulations were developed to simulate the group velocity control and the pulse compression processes. The group velocity as well as the pulse reshaping are solely controlled by external voltages which makes it promising in quantum information and quantum communication processes. It is also proposed that the group velocity can be changed even more in an Er doped crystal while at the same time having a transmission band matching the telecommunication wavelength.

  16. Proceedings of the workshop on ion source issues relevant to a pulsed spallation neutron source: Part 2 workshop presentations

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, L.; Leung, Ka-Ngo; Alonso, J. [eds.

    1994-10-01

    As part of the Lawrence Berkeley Laboratory Pulsed Spallation Source study, this Workshop was convened to address ion-source technology`s present status with respect to the next-generation Pulsed Spallation Source in the 1-5 MW range for the neutron scattering community. Considerations of Low Energy Beam Transport (LEBT) parameters and designs were included in the discussions throughout the Workshop. Ion-source requirements and actually-achieved performances were assessed, resulting in a determination of research and development requirements to bridge the gap. Part 1 of these Proceedings summarizes the Workshop; Part 2 contains viewgraphs of Workshop presentations.

  17. Nonlinear femtosecond pulse compression in cholesteric liquid crystals (Conference Presentation)

    Science.gov (United States)

    Liu, Yikun; Zhou, Jianying; Lin, Tsung-Hsien; Khoo, Iam-Choon

    2016-09-01

    Liquid crystals materials have the advantage of having a large nonlinear coefficient, but the response time is slow, normally up to several minisecond. This makes it is hard to apply in ultra fast optical devices. Recently, fentosecond (fs) nonlinear effect in choleteric liquid crystals is reported, nonlinear coefficient in the scale of 10-12 cm2/W is achieved. Base on this effect, in this work, fentosecond pulse compression technique in a miniature choleteric liquid crystal is demonstrated1,2. Cholesteric liquid crystals (CLC) is a kind of 1-dimensional phontonic structure with helical periodic. In a 10 μm thick CLC, femtosecond pulse with 100 fs is compressed to about 50 fs. CLC sample in planar texture with 500μm thick cell gap is further fabricated. In this sample, femtosecond pulse with 847 fs can be compressed to 286 fs. Due to the strong dispersion at the edge of photonic band gap, femtosecond pulse stretching and compensation can be achieve. In this experiment, laser pulse with duration 90 fs is stretched to above 2 picosecond in the first CLC sample and re-compressed to 120 fs in the second sample. Such technique might be applied in chirp pulse amplification. In conclusion, we report ultra fast nonlinear effect in cholesteric liquid crystals. Due to the strong dispersion and nonlinearity of CLC, femtosecond pulse manipulating devices can be achieved in the scale of micrometer.

  18. Excitation Waveform Design for Lamb Wave Pulse Compression.

    Science.gov (United States)

    Lin, Jing; Hua, Jiadong; Zeng, Liang; Luo, Zhi

    2016-01-01

    Most ultrasonic guided wave methods focus on tone burst excitation to reduce the effect of dispersion so as to facilitate signal interpretation. However, the resolution of the output cannot attain a very high value because time duration of the excitation waveform cannot be very small. To overcome this limitation, a pulse compression technique is introduced to Lamb wave propagation to achieve a δ-like correlation so as to obtain a high resolution for inspection. Ideal δ-like correlation is impossible as only a finite frequency bandwidth can propagate. The primary purpose of this paper is to design a proper excitation waveform for Lamb wave pulse compression, which shortens the correlation as close as possible to a δ function. To achieve this purpose, the performance of some typical signals is discussed in pulse compression, which include linear chirp (L-Chirp) signal, nonlinear chirp (NL-Chirp) signal, Barker code (BC), and Golay complementary code (GCC). In addition, how the excitation frequency range influences inspection resolution is investigated. A strategy for the frequency range determination is established subsequently. Finally, an experiment is carried out on an aluminum plate where these typical signals are used as excitations at different frequency ranges. The quantitative comparisons of the pulse compression responses validate the theoretical findings. By utilizing the experimental data, the improvement of pulse compression in resolution compared with tone burst excitation is also validated, and the robustness of the waveform design method to inaccuracies in the dispersion compensation is discussed as well.

  19. Spectral compression of single-photon-level laser pulse

    Science.gov (United States)

    Li, Yuanhua; Xiang, Tong; Nie, Yiyou; Sang, Minghuang; Chen, Xianfeng

    2017-01-01

    We experimentally demonstrate that the bandwidth of single photons laser pulse is compressed by a factor of 58 in a periodically poled lithium niobate (PPLN) waveguide chip. A positively chirped single photons laser pulse and a negatively chirped classical laser pulse are employed to produce a narrowband single photon pulse with new frequency through sum-frequency generation. In our experiment, the frequency and bandwidth of single photons at 1550 nm are simultaneously converted. Our results mark a critical step towards the realization of coherent photonic interface between quantum communication at 1550 nm and quantum memory in the near-visible window. PMID:28240245

  20. Short-Pulse Laser-Matter Computational Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Town, R; Tabak, M

    2004-11-02

    For three days at the end of August 2004, 55 plasma scientists met at the Four Points by Sheraton in Pleasanton to discuss some of the critical issues associated with the computational aspects of the interaction of short-pulse high-intensity lasers with matter. The workshop was organized around the following six key areas: (1) Laser propagation/interaction through various density plasmas: micro scale; (2) Anomalous electron transport effects: From micro to meso scale; (3) Electron transport through plasmas: From meso to macro scale; (4) Ion beam generation, transport, and focusing; (5) ''Atomic-scale'' electron and proton stopping powers; and (6) K{alpha} diagnostics.

  1. Compression of Electron Pulses for Femtosecond Electron Diffraction

    Science.gov (United States)

    Zandi, Omid; Yang, Jie; Centurion, Martin

    2014-05-01

    Our goal is to improve the temporal resolution in electron diffraction experiments to 100 fs by compressing the electron pulses using a time-varying electric field. The compressed pulse can be used for a better understanding of the dynamics of molecules under study. A bunch of 3 million electrons is generated at a photocathode by femtosecond UV laser pulses and accelerated to 100 keV in a static electric field. Then, the longitudinal component of the electric field of a microwave cavity is employed to compress the bunch. The cavity's frequency and phase are accurately tuned in such a way that the electric field is parallel to the bunch motion at its arrival and antiparallel to it at its exit. Compression in the transverse directions is done by magnetic lenses. Simulations have been done to predict the bunch profile at different positions and times by General Particle Tracer code. A streak camera has been built to measure the duration of the pulses. It uses the electric field of a discharging parallel plate capacitor to rotate the bunch so that angular spreading of the bunch is proportional to its duration. The capacitor is discharged by a laser pulse incident on a photo switch.

  2. Time-lens based optical packet pulse compression and retiming

    DEFF Research Database (Denmark)

    Laguardia Areal, Janaina; Hu, Hao; Palushani, Evarist;

    2010-01-01

    This paper presents a new optical circuit that performs both pulse compression and frame synchronization and retiming. Our design aims at directly multiplexing several 10G Ethernet data packets (frames) to a high-speed OTDM link. This scheme is optically transparent and does not require clock...

  3. Progress at SLAC on high-power rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Nantista, C.; Ruth, R.D. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Kroll, N.M. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)]|[California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

    1992-06-01

    Rf pulse compression is a technique for augmenting the peak power output of a klystron (typically 50--100 MW) to obtain the high peak power required to drive a linear collider at a high accelerating gradient (typically 200 MW/m is required for a gradient of 100 MV/m). The SLED pulse compression system, with a power gain of about 2.6, has been operational on the SLAC linac for more than a decade. Recently, a binary pulse-compression system with a power gain of about 5.2 has been tested up to an output power of 120 MW. Further high-power tests are in progress. Our current effort is focused on prototyping a so-called SLED-II pulse-compression system with a power gain of four. Over-moded TE{sub 01}-mode circular waveguide components, some with novel technical features, are used to reduce losses at the 11.4-GHz operating frequency.

  4. Progress at SLAC on high-power rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Nantista, C.; Ruth, R.D. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)); Kroll, N.M. (Stanford Linear Accelerator Center, Menlo Park, CA (United States) California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics)

    1992-06-01

    Rf pulse compression is a technique for augmenting the peak power output of a klystron (typically 50--100 MW) to obtain the high peak power required to drive a linear collider at a high accelerating gradient (typically 200 MW/m is required for a gradient of 100 MV/m). The SLED pulse compression system, with a power gain of about 2.6, has been operational on the SLAC linac for more than a decade. Recently, a binary pulse-compression system with a power gain of about 5.2 has been tested up to an output power of 120 MW. Further high-power tests are in progress. Our current effort is focused on prototyping a so-called SLED-II pulse-compression system with a power gain of four. Over-moded TE[sub 01]-mode circular waveguide components, some with novel technical features, are used to reduce losses at the 11.4-GHz operating frequency.

  5. The VELOCE pulsed power generator for isentropic compression experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Tommy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Asay, James Russell [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Chantrenne, Sophie J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hickman, Randall John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Willis, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Shay, Andrew W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Grine-Jones, Suzi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hall, Clint Allen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Baer, Melvin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Engineering Sciences Center

    2007-12-01

    Veloce is a medium-voltage, high-current, compact pulsed power generator developed for isentropic and shock compression experiments. Because of its increased availability and ease of operation, Veloce is well suited for studying isentropic compression experiments (ICE) in much greater detail than previously allowed with larger pulsed power machines such as the Z accelerator. Since the compact pulsed power technology used for dynamic material experiments has not been previously used, it is necessary to examine several key issues to ensure that accurate results are obtained. In the present experiments, issues such as panel and sample preparation, uniformity of loading, and edge effects were extensively examined. In addition, magnetohydrodynamic (MHD) simulations using the ALEGRA code were performed to interpret the experimental results and to design improved sample/panel configurations. Examples of recent ICE studies on aluminum are presented.

  6. SLED II: A new method of rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Ruth, R.D.

    1990-09-01

    In the SLED method of RF pulse compression, two high Q resonators store energy from an RF source for a relatively long time interval (typically 3 to 5 {mu}sec). Triggered by a reversal in RF phase, this stored energy is then released during a much shorter interval equal to the filling time of the accelerating structure. A peak power gain on the order of three and a compression efficiency on the order of 60% are typically attained. The shape of the output pulse is, however, a sharply decaying exponential. In SLED-II the two cavities are replaced by two lengths of resonant line, forming a Resonant Line SLED (RELS) and resulting in a flat output pulse. Therefore, RELS stages can be cascaded to give a greater peak power gain. Using two stages, a peak power gain greater than ten can be achieved with a reasonable compression efficiency. Unlike the BEC, the RELS compression factor per stage is not limited to two, albeit at the expense of intrinsic efficiency. Like the BEC, it uses long lines rather than short cavities.

  7. SLED II: A new method of rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Ruth, R.D.

    1990-09-01

    In the SLED method of RF pulse compression, two high Q resonators store energy from an RF source for a relatively long time interval (typically 3 to 5 {mu}sec). Triggered by a reversal in RF phase, this stored energy is then released during a much shorter interval equal to the filling time of the accelerating structure. A peak power gain on the order of three and a compression efficiency on the order of 60% are typically attained. The shape of the output pulse is, however, a sharply decaying exponential. In SLED-II the two cavities are replaced by two lengths of resonant line, forming a Resonant Line SLED (RELS) and resulting in a flat output pulse. Therefore, RELS stages can be cascaded to give a greater peak power gain. Using two stages, a peak power gain greater than ten can be achieved with a reasonable compression efficiency. Unlike the BEC, the RELS compression factor per stage is not limited to two, albeit at the expense of intrinsic efficiency. Like the BEC, it uses long lines rather than short cavities.

  8. Pulse temporal compression by two-stage stimulated Brillouin scattering and laser-induced breakdown

    Science.gov (United States)

    Liu, Zhaohong; Wang, Yulei; Wang, Hongli; Bai, Zhenxu; Li, Sensen; Zhang, Hengkang; Wang, Yirui; He, Weiming; Lin, Dianyang; Lu, Zhiwei

    2017-06-01

    A laser pulse temporal compression technique combining stimulated Brillouin scattering (SBS) and laser-induced breakdown (LIB) is proposed in which the leading edge of the laser pulse is compressed using SBS, and the low intensity trailing edge of the laser pulse is truncated by LIB. The feasibility of the proposed scheme is demonstrated by experiments in which a pulse duration of 8 ns is compressed to 170 ps. Higher compression ratios and higher efficiency are expected under optimal experimental conditions.

  9. A high-power SLED 2 pulse compression system

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, N.M. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Nantista, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics

    1992-03-01

    The enhancement of peak power by means of RF pulse compression has found important application for driving high energy electron linacs, the SLAC linac in particular. The SLAC Energy Doubler (SLED), however, yields a pulse shape in the form of a decaying exponential which limits the applicability of the method. Two methods of improving this situation have been suggested: binary pulse compression (BPC), in which the pulse is compressed by successive factors of two, and SLED II in which the pair of resonant cavities of SLED are replaced by long resonant delay lines (typically waveguides). Intermediate schemes in which the cavity pair is replaced by sequences of coupled cavities have also been considered. In this paper we describe our efforts towards the design and construction of high-power SLED II systems, which are intended to provide drivers for various advanced accelerator test facilities and potentially for the Next Linear Collider itself. The design path we have chosen requires the development of a number of microwave components in overmoded waveguide, and the bulk of this paper will be devoted to reporting our progress.

  10. Three-wave mixing mediated femtosecond pulse compression in β-barium borate.

    Science.gov (United States)

    Grün, A; Austin, Dane R; Cousin, Seth L; Biegert, J

    2015-10-15

    Nonlinear pulse compression mediated by three-wave mixing is demonstrated for ultrashort Ti:sapphire pulses in a type II phase-matched β-barium borate (BBO) crystal using noncollinear geometry. 170 μJ pulses at 800 nm with a pulse duration of 74 fs are compressed at their sum frequency to 32 fs with 55 μJ of pulse energy. Experiments and computer simulations demonstrate the potential of sum-frequency pulse compression to match the group velocities of the interacting waves to crystals that were initially not considered in the context of nonlinear pulse compression.

  11. Hollow-fiber compression of visible, 200 fs laser pulses to 40 fs pulse duration.

    Science.gov (United States)

    Procino, I; Velotta, R; Altucci, C; Amoruso, S; Bruzzese, R; Wang, X; Tosa, V; Sansone, G; Vozzi, C; Nisoli, M

    2007-07-01

    We demonstrate the use of a very simple, compact, and versatile method, based on the hollow-fiber compression technique, to shorten the temporal length of visible laser pulses of 100-300 fs to pulse durations shorter than approximately 50 fs. In particular, 200 fs, frequency-doubled, Nd:glass laser pulses (527 nm) were spectrally broadened to final bandwidths as large as 25 nm by nonlinear propagation through an Ar-filled hollow fiber. A compact, dispersive, prism-pair compressor was then used to produce as short as 40 fs, 150 microJ pulses. A very satisfactory agreement between numerical simulations and measurements is found.

  12. Two-klystron Binary Pulse Compression at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Vlieks, A.E.; Wang, J.W.; Wilson, P.B.

    1993-04-01

    The Binary Pulse Compression system installed at SLAC was tested using two klystrons, one with 10 MW and the other with 34 MW output. By compressing 560 ns klystron pulses into 70 ns, the measured BPC output was 175 MW, limited by the available power from the two klystrons. This output was used to provide 100-MW input to a 30-cell X-band structure in which a 100-MV/m gradient was obtained. This system, using the higher klystron outputs expected in the future has the potential to deliver the 350 MW needed to obtain 100 MV/m gradients in the 1.8-m NLC prototype structure. This note describes the timing, triggering, and phase coding used in the two-klystron experiment, and the expected and measured net-work response to three- or two-stage modulation.

  13. Spread spectrum compressed sensing MRI using chirp radio frequency pulses

    CERN Document Server

    Qu, Xiaobo; Zhuang, Xiaoxing; Yan, Zhiyu; Guo, Di; Chen, Zhong

    2013-01-01

    Compressed sensing has shown great potential in reducing data acquisition time in magnetic resonance imaging (MRI). Recently, a spread spectrum compressed sensing MRI method modulates an image with a quadratic phase. It performs better than the conventional compressed sensing MRI with variable density sampling, since the coherence between the sensing and sparsity bases are reduced. However, spread spectrum in that method is implemented via a shim coil which limits its modulation intensity and is not convenient to operate. In this letter, we propose to apply chirp (linear frequency-swept) radio frequency pulses to easily control the spread spectrum. To accelerate the image reconstruction, an alternating direction algorithm is modified by exploiting the complex orthogonality of the quadratic phase encoding. Reconstruction on the acquired data demonstrates that more image features are preserved using the proposed approach than those of conventional CS-MRI.

  14. Optimization of the output power of a pulsed gas laser by using magnetic pulse compression

    Science.gov (United States)

    Louhibi, D.; Ghobrini, Mourad; Bourai, K.

    1999-12-01

    In pulsed gas lasers, the excitation of the active medium is produced through the discharge of a storage capacitor. Performances of these lasers were essentially linked to the type of switch used and also to its mode of operation. Thyratrons are the most common switches. Nevertheless, their technological limitations do not allow a high repetition rate, necessary for optimization of the output power of this type of laser. These limitations can be surpassed by combining the thyratron to a one stage of a magnetic pulse compression circuit. The mpc driver can improve the laser excitation pulse rise time and increase the repetition rate, increasing the laser output power of pulsed gas laser such as; nitrogen, excimer and copper vapor lasers. We have proposed in this paper a new configuration of magnetic pulse compression, the magnetic switch is place in our case in the charge circuit, and while in the typical utilization of magnetic pulse compression, it is placed in the discharge circuit. In this paper, we are more particularly interested in the design and the modeling of a saturate inductance that represents the magnetic switch in the proposed configuration of a thyratron - mpc circuit combination.

  15. Enhanced soliton-effect pulse compression by cross-phase modulation in optical fibers

    Institute of Scientific and Technical Information of China (English)

    曹文华; 刘颂豪

    2000-01-01

    A new method is proposed to enhance the soliton-effect compression of optical pulses. It consists of copropagating two optical pulses with close wavelengths in the anomalous group-velocity dispersion regime of single-mode fibers. Numerical simulations show that, as compared with the traditional single pulse compression method, cross-phase modulation can not only dramatically increase the compression ratio but also decrease the optimum fiber length. The effects of initial pulse-width mismatch, Raman self-scattering, and pulse walk-off on the pulse compression are also discussed.

  16. Recent progress in the development of pulse compression gratings

    Directory of Open Access Journals (Sweden)

    Hocquet S.

    2013-11-01

    Full Text Available The PETAL facility uses chirped pulse amplification (CPA technique. This system needs large pulse compression gratings that request damage threshold better than 4 J/cm2 in normal beam at 1.053 μm for 500 fs pulses. In this paper, we will show recent grating designs with either multilayer dielectrics or hybrid metal-dielectric structures. We have shown in previous works that damage threshold is driven by the enhancement of the near electric field inside the pillars of the grating. This was evidenced from a macroscopic point of view by means of laser damage testing. We will show that damage morphology during damage initiation at the scale of the grating groove is also consistent with this electric field dependence.

  17. Optical pulse compression using a nonlinear optical loop mirror constructed from dispersion decreasing fiber

    Institute of Scientific and Technical Information of China (English)

    CAO; Wenhua; LIU; Songhao

    2004-01-01

    A novel scheme to compress optical pulses is proposed and demonstrated numerically, which is based on a nonlinear optical loop mirror constructed from dispersion decreasing fiber (DDF). We show that, in contrast to the conventional soliton-effect pulse compression in which compressed pulses are always accompanied by pedestals and frequency chirps owning to nonlinear effects, the proposed scheme can completely suppress pulse pedestals and frequency chirps. Unlike the adiabatic compression technique in which DDF length must increase exponentially with input pulsewidth, the proposed scheme does not require adiabatic condition and therefore can be used to compress long pulses by using reasonable fiber lengths. For input pulses with peak powers higher than a threshold value, the compressed pulses can propagate like fundamental solitons. Furthermore, the scheme is fairly insensitive to small variations in the loop length and is more robust to higher-order nonlinear effects and initial frequency chirps than the adiabatic compression technique.

  18. Spatiotemporal reshaping and compression of high intensity femtosecond pulses

    Science.gov (United States)

    Trunov, V. I.; Pestryakov, E. V.; Petrov, V. V.; Kirpichnikov, A. V.; Frolov, S. A.; Harenko, D. S.; Bagayev, S. N.

    2007-06-01

    Experimental results of self-compression of femtosecond pulses under filamentation in argon and xenon are presented. The mode of a self-compression in xenon is realized for the first time. The dependence of the spectrum broadening from pressure of these gases, input energy and focusing parameters are studied in detail. The spectral and temporary profiles of the first and the second filaments at multiple filamentation are analyzed. Features of multiple filamentation are revealed in xenon. For the first time experimentally the effect of restriction a number of filaments and effective swapping of energy from one filament to another (more than 70 % of energy in two-filament mode without increasing of their amount is founded). The possible mechanism of the phenomenon related with the saturation of the third order nonlinearity in xenon and influence of the higher fifth-order susceptibility χ (5) are discussed.

  19. Short-pulse, compressed ion beams at the Neutralized Drift Compression Experiment

    Science.gov (United States)

    Seidl, P. A.; Barnard, J. J.; Davidson, R. C.; Friedman, A.; Gilson, E. P.; Grote, D.; Ji, Q.; Kaganovich, I. D.; Persaud, A.; Waldron, W. L.; Schenkel, T.

    2016-05-01

    We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory, with 1-mm beam spot size within 2.5 ns full-width at half maximum. The ion kinetic energy is 1.2 MeV. To enable the short pulse duration and mm-scale focal spot radius, the beam is neutralized in a 1.5-meter-long drift compression section following the last accelerator cell. A short-focal-length solenoid focuses the beam in the presence of the volumetric plasma that is near the target. In the accelerator, the line-charge density increases due to the velocity ramp imparted on the beam bunch. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including select topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Below the transition to melting, the short beam pulses offer an opportunity to study the multi-scale dynamics of radiation-induced damage in materials with pump-probe experiments, and to stabilize novel metastable phases of materials when short-pulse heating is followed by rapid quenching. First experiments used a lithium ion source; a new plasma-based helium ion source shows much greater charge delivered to the target.

  20. Pulse Compression with Very Low Sidelobes in an Airborne Rain Mapping Rada

    Science.gov (United States)

    Tanner, A.; Durden, S.; Im, E.; Li, F.; Ricketts, W.; Wilsons, W.

    1993-01-01

    The pulse compression system for an airborne rain mapping rada is described. This system uses time domain weighting of the transmit pulse and is able to achive a pulse compression sidelobe level of -55 dB. This is significantly lower than any values previously reported in the open literature.

  1. Linear optical pulse compression based on temporal zone plates.

    Science.gov (United States)

    Li, Bo; Li, Ming; Lou, Shuqin; Azaña, José

    2013-07-15

    We propose and demonstrate time-domain equivalents of spatial zone plates, namely temporal zone plates, as alternatives to conventional time lenses. Both temporal intensity zone plates, based on intensity-only temporal modulation, and temporal phase zone plates, based on phase-only temporal modulation, are introduced and studied. Temporal zone plates do not exhibit the limiting tradeoff between temporal aperture and frequency bandwidth (temporal resolution) of conventional linear time lenses. As a result, these zone plates can be ideally designed to offer a time-bandwidth product (TBP) as large as desired, practically limited by the achievable temporal modulation bandwidth (limiting the temporal resolution) and the amount of dispersion needed in the target processing systems (limiting the temporal aperture). We numerically and experimentally demonstrate linear optical pulse compression by using temporal zone plates based on linear electro-optic temporal modulation followed by fiber-optics dispersion. In the pulse-compression experiment based on temporal phase zone plates, we achieve a resolution of ~25.5 ps over a temporal aperture of ~5.77 ns, representing an experimental TBP larger than 226 using a phase-modulation amplitude of only ~0.8π rad. We also numerically study the potential of these devices to achieve temporal imaging of optical waveforms and present a comparative analysis on the performance of different temporal intensity and phase zone plates.

  2. Design of Excitatory Signal and Matched Filter for Compressed Pulsed Radar

    Directory of Open Access Journals (Sweden)

    Argel Gonzalez Padilla

    2013-11-01

    Full Text Available In this paper is presented pulse compression technique in radar, focusing on Linear Frequency Modulation (LFM. Matched Filter characteristics are the elements considered for pulse compression, algebraic operations are derived to avoid the signal phase effect received by detection capacity. A hardware system for pulse compression in language description hardware is implemented. The product obtained is a first step in radar techniques to improve resolution capacity.

  3. Short-Pulse, Compressed Ion Beams at the Neutralized Drift Compression Experiment

    CERN Document Server

    Seidl, Peter A; Davidson, Ronald C; Friedman, Alex; Gilson, Erik P; Grote, David; Ji, Qing; Kaganovich, I D; Persaud, Arun; Waldron, William L; Schenkel, Thomas

    2016-01-01

    We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory, with 1-mm beam spot size within 2.5 ns full-width at half maximum. The ion kinetic energy is 1.2 MeV. To enable the short pulse duration and mm-scale focal spot radius, the beam is neutralized in a 1.5-meter-long drift compression section following the last accelerator cell. A short-focal-length solenoid focuses the beam in the presence of the volumetric plasma that is near the target. In the accelerator, the line-charge density increases due to the velocity ramp imparted on the beam bunch. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including select topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Below the transition to melting, the short beam pulses offer an opportunity to study the multi-scale dynam...

  4. Nonlinear Pulse Compression and Reshaping Using Cross-Phase Modulation in a Dispersion-Shifted Fiber

    Institute of Scientific and Technical Information of China (English)

    S.; W.; Chan; K.; K.; Chow; C.; Shu

    2003-01-01

    Nonlinear pulse compression has been demonstrated by cross-phase modulation in a dispersion-shifted fiber. The output is obtained from filtering of the broadened optical spectrum and a pulse width reduction from 61 to 28 ps is achieved.

  5. Generating ultra-short energetic pulses with cascaded soliton compression in lithium niobate crystals

    DEFF Research Database (Denmark)

    Zhou, Binbin; Bache, Morten; Chong, A.;

    2010-01-01

    By launching energetic femtosecond pulses in a lithium niobate crystal, the phase mismatched second-harmonic generation process compresses the 50 fs input pulse at 1250 nm to 30 fs through a soliton effect.......By launching energetic femtosecond pulses in a lithium niobate crystal, the phase mismatched second-harmonic generation process compresses the 50 fs input pulse at 1250 nm to 30 fs through a soliton effect....

  6. Spectral Compression of Intense Femtosecond Pulses by Self Phase Modulation in Silica Glass

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Zhou, Binbin; Bache, Morten

    2012-01-01

    We experimentally demonstrate spectral compression of mJ fs pulses by self phase modulation in silica glass. Spectral narrowing by factor 2.4 of near-transform-limited pulses is shown, with good agreement between experiment and numerical simulation.......We experimentally demonstrate spectral compression of mJ fs pulses by self phase modulation in silica glass. Spectral narrowing by factor 2.4 of near-transform-limited pulses is shown, with good agreement between experiment and numerical simulation....

  7. Pulse generation and compression using an asymmetrical porous silicon-based Mach–Zehnder interferometer configuration

    Indian Academy of Sciences (India)

    SHU-WEN GUO; JIAN-WEI WU

    2016-12-01

    We propose an asymmetrical Mach–Zehnder interferometer (MZI) for efficient pulse generation and compression using porous silicon (PS) waveguide, fibre delay line and couplers. We show a pulse compression of about 0.4 ns at the output port with third-order super-Gaussian input pulse in ∼2 ns time duration and ∼40.3 W peak power level. Also, we show the possibility of obtaining compressed single- or double-pulse with judicious choice of various parameters like input peak power, delay time and input pulse width.

  8. Pulse compression radar reflectometry for density measurements on fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Costley, A.; Prentice, R. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Laviron, C. [Compagnie Generale des Matieres Nucleaires (COGEMA), 78 - Velizy-Villacoublay (France); Prentice, R. [Toulouse-3 Univ., 31 (France). Centre d`Etude Spatiale des Rayonnements

    1994-07-01

    On tokamaks and other toroidal machines, reflectometry is a very rapidly developing technique for density profile measurements, particularly near the edge. Its principle relies on the total reflection of an electromagnetic wave at a cutoff layer, where the critical density is reached and the local refractive index goes to zero. With the new fast frequency synthesizers now available, a method based on pulse compression radar is proposed for plasma reflectometry, overcoming the limitations of the previous reflectometry methods. The measurement can be made on a time-scale which is effectively very short relatively to the plasma fluctuations, and the very high reproducibility and stability of the source allows an absolute calibration of the waveguides to be made, which corrects for the effects of the parasitic reflections. 2 refs., 5 figs.

  9. Few-cycle fiber pulse compression and evolution of negative resonant radiation

    CERN Document Server

    McLenaghan, Joanna

    2013-01-01

    We present numerical simulations and experimental observations of the spectral expansion of fs-pulses compressing in optical fibers. Using the input pulse frequency chirp we are able to scan through the pulse compression spectra and observe in detail the emergence of negative-frequency resonant radiation (NRR), a recently discovered pulse instability coupling to negative frequencies [Rubino et al., PRL 108, 253901 (2012)]. We observe how the compressing pulse is exciting NRR as long as it overlaps spectrally with the resonant frequency. Furthermore, we observe that optimal pulse compression can be achieved at an optimal input chirp and for an optimal fiber length. The results are important for Kerr-effect pulse compressors, to generate novel light sources, as well as for the observation of quantum vacuum radiation.

  10. Compression of realistic laser pulses in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, John

    2009-01-01

    Dispersive compression of chirped few-picosecond pulses at the microjoule level in a hollow-core photonic bandgap fiber is studied numerically. The performance of ideal parabolic input pulses is compared to pulses from a narrowband picosecond oscillator broadened by self-phase modulation during...

  11. ASIC Design and Implementation for Digital Pulse Compression Chip

    Institute of Scientific and Technical Information of China (English)

    高俊峰; 韩月秋; 王巍

    2004-01-01

    A novel ASIC design of changeable-point digital pulse compression (DPC) chip is presented. System hardware resource is reduced to one third of the traditional design method through operations sharing hardware, i.e. let FFT, complex multiplication and IFFT be fulfilled with the same hardware structure. Block-floating-point scaling is used to enhance the dynamic range and computation accuracy. This design applies parallel pipeline structure and the radix-4 butterfly operation to improve the processing speed. In addition, a triple-memory-space(TMS) configuration is used that allows input, computation and output operations to be overlapped, so that the dual-butterfly unit is never left in an idle state waiting for I/O operation. The whole design is implemented with only one chip of XC2V500-5 FPGA. It can implement 1 024-point DPC within 91.6 μs.The output data is converted to floating-point formation to achieve seamless interface with TMS320C6701. The validity of the design is verified by simulation and measurement results.

  12. Suppression of stimulated Brillouin scattering with phase modulator in soliton pulse compression

    Institute of Scientific and Technical Information of China (English)

    Bo Lü; Taorong Gong; Ming Chen; Muguang Wang; Tangjun Li; Genxiang Chen; Shuisheng Jian

    2009-01-01

    A phase modulator is employed in the scheme of soliton pulse compression with dispersion shifted fiber (DSF). Stimulated Brillouin scattering (SBS) effect, as a negative influence here, can be dramatically suppressed after optical phase modulation. The experimental result shows that the launched power required for high-order soliton pulse compression has been significantly increased by 11 dB under the condition of 100-MHz phase modulation. Accordingly, the experiment of picosecond pulse compression generated from electro-absorption sampling window (EASW) has also been implemented.

  13. Optimal Design and Experimental characterisation of short optical pulse compression using CDPF

    DEFF Research Database (Denmark)

    Yujun, Qian; Quist, S.

    1999-01-01

    We present optimal design and experimental characterisation ofoptical pulse compression using a comblike dispersion-profiled fibre(CDPF). A pulse train at 10GHz with puslewidth of 1ps and side-lobesuppression of 30dB can be obtained.......We present optimal design and experimental characterisation ofoptical pulse compression using a comblike dispersion-profiled fibre(CDPF). A pulse train at 10GHz with puslewidth of 1ps and side-lobesuppression of 30dB can be obtained....

  14. Efficient spectral shift and compression of femtosecond pulses by parametric amplification of chirped light.

    Science.gov (United States)

    Nejbauer, Michał; Radzewicz, Czesław

    2012-01-30

    We present a method for an efficient spectral shift and compression of pulses from a femtosecond laser system. The method enables generation of broadly tunable (615-985 nm) narrow bandwidth (≈10 cm(-1)) pulses from the femtosecond pulses at 1030 nm. It employs a direct parametric amplification--without spectral filtering--of highly chirped white light by a narrow bandwidth (pulse. The system, when pumped with just 200 μJ of the fundamental femtosecond pulse energy, generates pulses with energies of 3-9 μJ and an excellent beam quality in the entire tuning range.

  15. High power microwave system based on power combining and pulse compression of conventional klystrons

    CERN Document Server

    Xiong, Zheng-Feng; Cheng, Cheng; Ning, Hui; Tang, Chuan-Xiang

    2015-01-01

    A high power microwave system based on power combining and pulse compression of conventional klystrons is introduced in this paper. This system mainly consists of pulse modulator, power combiner, driving source of klystrons and pulse compressor. A solid state induction modulator and pulse transformer were used to drive two 50 MW S-band klystrons with pulse widths 4 {\\mu}s in parallel, after power combining and pulse compression, the tested peak power had reached about 210 MW with pulse widths nearly 400 ns at 25 Hz, while the experimental maximum output power was just limited by the power capacity of loads. This type of high power microwave system has widely application prospect in RF system of large scale particle accelerators, high power radar transmitters and high level electromagnetic environment generators.

  16. Compressed 6 ps pulse in nonlinear amplification of a Q-switched microchip laser

    Science.gov (United States)

    Diao, Ruxin; Liu, Zuosheng; Niu, Fuzeng; Wang, Aimin; Taira, Takunori; Zhang, Zhigang

    2017-02-01

    We present a passively Q-switched Nd:YVO4 crystal microchip laser with a 6 ps pulse width, which is based on SPM-induced spectral broadening and pulse compression. The passive Q-switching is obtained by a semiconductor saturable absorber mirror. The laser’s seed source centered at 1064 nm pulses with a duration of 80 ps, at a repetition rate of 600 kHz corresponding to an average output power of 10 mW. After amplification and compression, the pulses were compressed to 6 ps with a maximum pulse energy of 0.5 µJ.

  17. High-energy-throughput pulse compression by off-axis group-delay compensation in a laser-induced filament

    Energy Technology Data Exchange (ETDEWEB)

    Voronin, A. A. [Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Alisauskas, S.; Muecke, O. D.; Pugzlys, A.; Baltuska, A. [Photonics Institute, Vienna University of Technology, Gusshausstrasse 27-387, 1040 Vienna (Austria); Zheltikov, A. M. [Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843-3257 (United States)

    2011-08-15

    Off-axial beam dynamics of ultrashort laser pulses in a filament enable a radical energy-throughput improvement for filamentation-assisted pulse compression. We identify regimes where a weakly diverging wave, produced on the trailing edge of the pulse, catches up with a strongly diverging component, arising in the central part of the pulse, allowing sub-100-fs millijoule infrared laser pulses to be compressed to 20-25-fs pulse widths with energy throughputs in excess of 70%. Theoretical predictions have been verified by experimental results on filamentation-assisted compression of 70-fs, 1.5-{mu}m laser pulses in high-pressure argon.

  18. Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: I. general description

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, Igor D., E-mail: ikaganov@pppl.gov [Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Massidda, Scott; Startsev, Edward A.; Davidson, Ronald C. [Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Vay, Jean-Luc [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Friedman, Alex [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States)

    2012-06-21

    Neutralized drift compression offers an effective means for particle beam pulse compression and current amplification. In neutralized drift compression, a linear longitudinal velocity tilt (head-to-tail gradient) is applied to the non-relativistic beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam current can increase by more than a factor of 100 in the longitudinal direction. We have performed an analytical study of how errors in the velocity tilt acquired by the beam in the induction bunching module limit the maximum longitudinal compression. It is found that the compression ratio is determined by the relative errors in the velocity tilt. That is, one-percent errors may limit the compression to a factor of one hundred. However, a part of the beam pulse where the errors are small may compress to much higher values, which are determined by the initial thermal spread of the beam pulse. It is also shown that sharp jumps in the compressed current density profile can be produced due to overlaying of different parts of the pulse near the focal plane. Examples of slowly varying and rapidly varying errors compared to the beam pulse duration are studied. For beam velocity errors given by a cubic function, the compression ratio can be described analytically. In this limit, a significant portion of the beam pulse is located in the broad wings of the pulse and is poorly compressed. The central part of the compressed pulse is determined by the thermal spread. The scaling law for maximum compression ratio is derived. In addition to a smooth variation in the velocity tilt, fast-changing errors during the pulse may appear in the induction bunching module if the voltage pulse is formed by several pulsed elements. Different parts of the pulse compress nearly simultaneously at the target and the compressed profile may have many peaks. The maximum compression is a function of both thermal spread and the velocity errors. The effects of the

  19. Advanced numerical studies of the neutralized drift compression of intense ion beam pulses

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2007-10-01

    Full Text Available Longitudinal bunch compression of intense ion beams for warm dense matter and heavy ion fusion applications occurs by imposing an axial velocity tilt onto an ion beam across the acceleration gap of a linear induction accelerator, and subsequently allowing the beam to drift through plasma in order to neutralize its space-charge and current as the pulse compresses. The detailed physics and implications of acceleration gap effects and focusing aberration on optimum longitudinal compression are quantitatively reviewed using particle-in-cell simulations, showing their dependence on many system parameters. Finite-size gap effects are shown to result in compression reduction, due to an increase in the effective longitudinal temperature imparted to the beam, and a decrease in intended fractional tilt. Sensitivity of the focal plane quality to initial longitudinal beam temperature is explored, where slower particles are shown to experience increased levels of focusing aberration compared to faster particles. A plateau effect in axial compression is shown to occur for larger initial pulse lengths, where the increases in focusing aberration over the longer drift lengths involved dominate the increases in relative compression, indicating a trade-off between current compression and pulse duration. The dependence on intended fractional tilt is also discussed and agrees well with theory. A balance between longer initial pulse lengths and larger tilts is suggested, since both increase the current compression, but have opposite effects on the final pulse length, drift length, and amount of longitudinal focusing aberration. Quantitative examples are outlined that explore the sensitive dependence of compression on the initial kinetic energy and thermal distribution of the beam particles. Simultaneous transverse and longitudinal current density compression can be achieved in the laboratory using a strong final-focus solenoid, and simulations addressing the effects

  20. Generation of high energy, 30 fs pulses at 527 nm by hollow-fiber compression technique.

    Science.gov (United States)

    Xia, J; Altucci, C; Amoruso, S; Bruzzese, R; Velotta, R; Wang, X

    2008-03-17

    The compression of 300-fs-long, chirp-free laser pulses at 527 nm down to 30 fs is reported. The laser pulses, originated from a frequency-doubled, mode-locked Nd:glass laser, were compressed by a 0.7-m-long, 150-microm-bore-diameter, argon-filled hollow fiber, and a pair of SF10 prisms with a final energy of 160 microJ. These are the shortest, high energy pulses ever produced by direct pulse compression at the central wavelength of 527 nm. The spectral broadening of the pulses propagating inside the hollow fiber was experimentally examined for various filling-gas pressures and input pulse energies. The spectral width of the pulses was broadened up to 25 nm, and 27 nm for argon- and krypton-filled hollow fiber, respectively, at a gas pressure lower than 2 bar. The physical limitations of the hollow-fiber pulse compression technique applied in the visible range are also studied.

  1. High-Power Multimode X-Band RF Pulse Compression System for Future Linear Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Tantawi, S.G.; Nantista, C.D.; Dolgashev, V.A.; Pearson, C.; Nelson, J.; Jobe, K.; Chan, J.; Fant, K.; Frisch, J.; /SLAC; Atkinson, D.; /LLNL, Livermore

    2005-08-10

    We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC). The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II) pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

  2. Report on the international workshop on cold moderators for pulsed neutron sources.

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, J. M.

    1999-01-06

    The International Workshop on Cold Moderators for Pulsed Neutron Sources resulted from the coincidence of two forces. Our sponsors in the Materials Sciences Branch of DOE's Office of Energy Research and the community of moderator and neutron facility developers both realized that it was time. The Neutron Sources Working Group of the Megascience Forum of the Organization for Economic Cooperation and Development offered to contribute its support by publishing the proceedings, which with DOE and Argonne sponsorship cemented the initiative. The purposes of the workshop were: to recall and improve the theoretical groundwork of time-dependent neutron thermalization; to pose and examine the needs for and benefits of cold moderators for neutron scattering and other applications of pulsed neutron sources; to summarize experience with pulsed source, cold moderators, their performance, effectiveness, successes, problems and solutions, and the needs for operational data; to compile and evaluate new ideas for cold moderator materials and geometries; to review methods of measuring and characterizing pulsed source cold moderator performance; to appraise methods of calculating needed source characteristics and to evaluate the needs and prospects for improvements; to assess the state of knowledge of data needed for calculating the neutronic and engineering performance of cold moderators; and to outline the needs for facilities for testing various aspects of pulsed source cold moderator performance.

  3. Pulse Compression by Filamentation in Argon with an Acoustic Optical Programmable Dispersive Filter for Predispersion Compensation

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-Wei; JIANG Yong-Liang; LENG Yu-Xin; LIU Jun; GE Xiao-Chun; LI Ru-Xin; XU Zhi-Zhan

    2006-01-01

    @@ We have experimentally demonstrated pulses 0.4 mJ in duration smaller than 12 fs with an excellent spatial beam profile by self-guided propagation in argon. The original 52fs pulses from the chirped pulsed amplification laser system are first precompressed to 32 fs by inserting an acoustic optical programmable dispersive filter instrument into the laser system for spectrum reshaping and dispersion compensation, and the pulse spectrum is subsequently broadened by filamentation in an argon cell. By using chirped mirrors for post-dispersion compensation, the pulses are successfully compressed to smaller than 12fs.

  4. Nonlinear pulse compression of picosecond parabolic-like pulses synthesized with a long period fiber grating filter.

    Science.gov (United States)

    Krcmarík, David; Slavík, Radan; Park, Yongwoo; Azaña, José

    2009-04-27

    tract: We demonstrate high quality pulse compression at high repetition rates by use of spectral broadening of short parabolic-like pulses in a normally-dispersive highly nonlinear fiber (HNLF) followed by linear dispersion compensation with a conventional SMF-28 fiber. The key contribution of this work is on the use of a simple and efficient long-period fiber grating (LPFG) filter for synthesizing the desired parabolic-like pulses from sech(2)-like input optical pulses; this all-fiber low-loss filter enables reducing significantly the required input pulse power as compared with the use of previous all-fiber pulse re-shaping solutions (e.g. fiber Bragg gratings). A detailed numerical analysis has been performed in order to optimize the system's performance, including investigation of the optimal initial pulse shape to be launched into the HNLF fiber. We found that the pulse shape launched into the HNLF is critically important for suppressing the undesired wave breaking in the nonlinear spectral broadening process. The optimal shape is found to be independent on the parameters of normally dispersive HNLFs. In our experiments, 1.5-ps pulses emitted by a 10-GHz mode-locked laser are first reshaped into 3.2-ps parabolic-like pulses using our LPFG-based pulse reshaper. Flat spectrum broadening of the amplified initial parabolic-like pulses has been generated using propagation through a commercially-available HNLF. Pulses of 260 fs duration with satellite peak and pedestal suppression greater than 17 dB have been obtained after the linear dispersion compensation fiber. The generated pulses exhibit a 20-nm wide supercontinuum energy spectrum that has almost a square-like spectral profile with >85% of the pulse energy contained in its FWHM spectral bandwidth.

  5. Temporal and lateral electron pulse compression by a compact spherical electrostatic capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Grzelakowski, Krzysztof P., E-mail: kgrzelakowski@op.pl [OPTICON Nanotechnology, Muchoborska 18, PL54-424 Wrocław (Poland); Tromp, Rudolf M. [IBM Research Division, T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)

    2013-07-15

    A novel solution for high intensity electron pulse compression in both space and time is proposed in this paper. Based on the unique properties of the central-force electrostatic field of a spherical electrostatic capacitor, the newly developed α-Spherical Deflector Analyzer (α-SDA) with 2π total deflection is utilized for the practical realization of femtosecond electron pulse compression. The mirror symmetry of the system at π deflection causes not only the cancellation of the geometrical and chromatic aberrations at 2π, but also leads to aberration-free time reversal of the electron pulse in the exit plane. As a consequence, the time-divergent electrons at the input are transformed to a time-convergent pulse at the output. In the symmetric case with the first time compression exactly at π, the shortest electron pulse behind the α-SDA analyzer is a mirror symmetric to the original electron pulse at the photocathode. It results in extremely short final electron pulses that are limited only by the duration of the laser pulse, the emittance of the electron bunch, and by imperfections of the real system. - Highlights: • We propose a new method for spatial and temporal compression of ultrafast electron pulses. • Compact in-line construction is based on the idea of the spherical electrostatic capacitor (α-SDA). • It is free of chromatic, geometrical and temporal aberrations after 2π deflection. • Contrary to other methods it enables time reversal of the pulse with static electric fields only. • Spatial and temporal focus can be independently fine-adjusted at the target position.

  6. Complete temporal characterisation of asymmetric pulse compression in a laser wakefield

    CERN Document Server

    Schreiber, J; Mangles, S P D; Kamperidis, C; Kneip, S; Nagel, S R; Palmer, C A J; Rajeev, P P; Najmudin, Z

    2010-01-01

    We present complete experimental characterisation of the temporal shape of an intense ultrashort 200-TW laser pulse driving a laser wakefield. The phase of the pulse was uniquely measured using (second order) frequency resolved optical gating (FROG). The pulses are asymmetrically compressed, and exhibit a positive chirp consistent with the expected asymmetric self-phase modulation due to photon acceleration/deceleration in a relativistic plasma wave. The measured pulse duration decreases linearly with increasing length and density of the plasma, in quantitative agreement with the intensity dependent group velocity variation in the plasma wave.

  7. Subpicosecond pulse compression in nonlinear photonic crystal waveguides based on the formation of high-order optical solitons

    Institute of Scientific and Technical Information of China (English)

    Chen Xiong-Wen; Lin Xu-Sheng; Lan Sheng

    2005-01-01

    We investigate by numerical simulation the compression of subpicosecond pulses in two-dimensional nonlinear photonic crystal (PC) waveguides. The compression originates from the generation of high-order optical solitons through the interplay of the huge group-velocity dispersion and the enhanced self-phase modulation in nonlinear PC waveguides.Both the formation of Bragg grating solitons and gap solitons can lead to efficient pulse compression. The compression factors under different excitation power densities and the optimum length for subpicosecond pulse compression have been determined. As a compressor, the total length of the nonlinear PC waveguide is only ten micrometres and therefore can be easily incorporated into PC integrated circuits.

  8. High-degree pulse compression and high-coherence supercontinuum generation in a convex dispersion profile

    Science.gov (United States)

    Li, Qian; Kutz, J. Nathan; Wai, P. K. A.

    2013-08-01

    We consider the non-adiabatic pulse compression of cascaded soliton propagating in three consecutive optical fiber segments, each of which has a convex dispersion profile with two zero-dispersion wavelengths. The convex dispersion profile provides an accurate description of the chromatic dispersion over the whole frequency range, thus allowing for a comprehensive theoretical treatment of the cascaded third order soliton compression when ultrashort pulses (DFDF) has a convex curvature in its dispersion profile which varies along length of fiber. Compared to DFDF, the cascading of fiber segments with convex dispersion that stays constant along the fiber length greatly reduces the manufacture difficulties and provides a much simpler engineering design in practice. High-degree pulse compression and high-coherence supercontinuum generation are demonstrated.

  9. High-power radio-frequency binary pulse-compression experiment at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Lavine, T.L.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Spalek, G.; Wilson, P.B.

    1991-05-01

    Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at power levels up to 25-MW input (from an X-Band klystron) and up to 120-MW output (compressed to 60 nsec). Peak power gains greater than 5.2 have been measured. 5 refs., 6 figs., 5 tabs.

  10. Characteristics of perfluorinated amine media for stimulated Brillouin scattering in hundreds of picoseconds pulse compression at 532 nm

    Institute of Scientific and Technical Information of China (English)

    Wuliji Hasi; Hang Zhao; Dianyang Lin; Weiming He; Zhiwei Lü

    2015-01-01

    The characteristics of stimulated Brillouin scattering (SBS) in perfluorinated amine media and the experimental structure used in hundreds of picoseconds pulse compression at 532 nm are demonstrated.A two-stage SBS pulse compression structure is adopted for this work.The compact double-cell SBS compression structure and the scattering media FC-70 are chosen to compress the incident light from 9.5 to about 1 ns in the first stage.Then,the light is used as the pumping source for the second pulse compression.In the second stage,using a single-cell SBS structure in a pulse compression system,perfluorinated amine media with different phonon lifetimes,such as FC-3283,FC-40,FC-43,and FC-70,are chosen to run the comparative experimental study.The narrowest compressed pulse times obtained are 294,274,277,and 194 ps;they respectively correspond to the above listed media.The average width of the compressed pulse width is 320 ps for FC-3283,with a fluctuation range of 87 ps.For FC-40,the average pulse width is 320 ps,with a fluctuation range of 72 ps.And for FC-43,the average pulse width is 335 ps,with a fluctuation range of 88 ps.However,the average pulse width is only 280 ps for FC-70,with a fluctuation range of 57 ps.The highest energy reflectivity is more than 80% for all of the media.The experimental results show that a two-stage SBS pulse compression system has lower pump energy requirements,thus making it easier to achieve a compressed pulse waveform.The results also show that the shorter the phonon lifetime of the medium,the narrower the obtained compressed pulse width.

  11. Compressive strength evaluation of structural lightweight concrete by non-destructive ultrasonic pulse velocity method.

    Science.gov (United States)

    Bogas, J Alexandre; Gomes, M Glória; Gomes, Augusto

    2013-07-01

    In this paper the compressive strength of a wide range of structural lightweight aggregate concrete mixes is evaluated by the non-destructive ultrasonic pulse velocity method. This study involves about 84 different compositions tested between 3 and 180 days for compressive strengths ranging from about 30 to 80 MPa. The influence of several factors on the relation between the ultrasonic pulse velocity and compressive strength is examined. These factors include the cement type and content, amount of water, type of admixture, initial wetting conditions, type and volume of aggregate and the partial replacement of normal weight coarse and fine aggregates by lightweight aggregates. It is found that lightweight and normal weight concretes are affected differently by mix design parameters. In addition, the prediction of the concrete's compressive strength by means of the non-destructive ultrasonic pulse velocity test is studied. Based on the dependence of the ultrasonic pulse velocity on the density and elasticity of concrete, a simplified expression is proposed to estimate the compressive strength, regardless the type of concrete and its composition. More than 200 results for different types of aggregates and concrete compositions were analyzed and high correlation coefficients were obtained.

  12. High-power rf pulse compression with SLED-II at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Nantista, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Kroll, N.M. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Tantawi, S.G.; Vlieks, A.E.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1993-04-01

    Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE{sub 01} mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator).

  13. High-power rf pulse compression with SLED-II at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Nantista, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Kroll, N.M. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Tantawi, S.G.; Vlieks, A.E.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1993-04-01

    Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE{sub 01} mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator).

  14. Design and fabrication of hollow-core photonic crystal fibers for high-power ultrashort pulse transportation and pulse compression.

    Science.gov (United States)

    Wang, Y Y; Peng, Xiang; Alharbi, M; Dutin, C Fourcade; Bradley, T D; Gérôme, F; Mielke, Michael; Booth, Timothy; Benabid, F

    2012-08-01

    We report on the recent design and fabrication of kagome-type hollow-core photonic crystal fibers for the purpose of high-power ultrashort pulse transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all kagome fibers) of 40 dB/km over a broadband transmission centered at 1500 nm. We show that the large core size, low attenuation, broadband transmission, single-mode guidance, and low dispersion make it an ideal host for high-power laser beam transportation. By filling the fiber with helium gas, a 74 μJ, 850 fs, and 40 kHz repetition rate ultrashort pulse at 1550 nm has been faithfully delivered at the fiber output with little propagation pulse distortion. Compression of a 105 μJ laser pulse from 850 fs down to 300 fs has been achieved by operating the fiber in ambient air.

  15. High-power multimode X-band rf pulse compression system for future linear colliders

    Directory of Open Access Journals (Sweden)

    Sami G. Tantawi

    2005-04-01

    Full Text Available We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC. The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

  16. Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: II. Analysis of experimental data of the Neutralized Drift Compression eXperiment-I (NDCX-I)

    Science.gov (United States)

    Massidda, Scott; Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.; Lidia, Steven M.; Seidl, Peter; Friedman, Alex

    2012-06-01

    Neutralized drift compression offers an effective means for particle beam focusing and current amplification with applications to heavy ion fusion. In the Neutralized Drift Compression eXperiment-I (NDCX-I), a non-relativistic ion beam pulse is passed through an inductive bunching module that produces a longitudinal velocity modulation. Due to the applied velocity tilt, the beam pulse compresses during neutralized drift. The ion beam pulse can be compressed by a factor of more than 100; however, errors in the velocity modulation affect the compression ratio in complex ways. We have performed a study of how the longitudinal compression of a typical NDCX-I ion beam pulse is affected by the initial errors in the acquired velocity modulation. Without any voltage errors, an ideal compression is limited only by the initial energy spread of the ion beam, ΔΕb. In the presence of large voltage errors, δU≫ΔEb, the maximum compression ratio is found to be inversely proportional to the geometric mean of the relative error in velocity modulation and the relative intrinsic energy spread of the beam ions. Although small parts of a beam pulse can achieve high local values of compression ratio, the acquired velocity errors cause these parts to compress at different times, limiting the overall compression of the ion beam pulse.

  17. Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: II. Analysis of experimental data of the Neutralized Drift Compression eXperiment-I (NDCX-I)

    Energy Technology Data Exchange (ETDEWEB)

    Massidda, Scott [Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Kaganovich, Igor D., E-mail: ikaganov@pppl.gov [Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Startsev, Edward A.; Davidson, Ronald C. [Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Lidia, Steven M.; Seidl, Peter [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Friedman, Alex [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States)

    2012-06-21

    Neutralized drift compression offers an effective means for particle beam focusing and current amplification with applications to heavy ion fusion. In the Neutralized Drift Compression eXperiment-I (NDCX-I), a non-relativistic ion beam pulse is passed through an inductive bunching module that produces a longitudinal velocity modulation. Due to the applied velocity tilt, the beam pulse compresses during neutralized drift. The ion beam pulse can be compressed by a factor of more than 100; however, errors in the velocity modulation affect the compression ratio in complex ways. We have performed a study of how the longitudinal compression of a typical NDCX-I ion beam pulse is affected by the initial errors in the acquired velocity modulation. Without any voltage errors, an ideal compression is limited only by the initial energy spread of the ion beam, {Delta}{Epsilon}{sub b}. In the presence of large voltage errors, {delta}U Double-Nested-Greater-Than {Delta}E{sub b}, the maximum compression ratio is found to be inversely proportional to the geometric mean of the relative error in velocity modulation and the relative intrinsic energy spread of the beam ions. Although small parts of a beam pulse can achieve high local values of compression ratio, the acquired velocity errors cause these parts to compress at different times, limiting the overall compression of the ion beam pulse.

  18. Doppler Properties of Polyphase Coded Pulse Compression Waveforms.

    Science.gov (United States)

    1982-09-30

    phase structure. An example is shown in Fig. 12 for a PI code. Each code can be generated or compressed with the same standard FFT phase filter shown...in Fig. 13. The phase shifts used before and after the FFT phase filter depend on the particular code. One way to reduce the 4-dB cyclic variation of...could be achieved by the use of additional phase shifters and delay lines in the F, output ports of the FFT phase filter shown in Fig. 12. EXPANSION r r

  19. Compact rf polarizer and its application to pulse compression systems

    Science.gov (United States)

    Franzi, Matthew; Wang, Juwen; Dolgashev, Valery; Tantawi, Sami

    2016-06-01

    We present a novel method of reducing the footprint and increasing the efficiency of the modern multi-MW rf pulse compressor. This system utilizes a high power rf polarizer to couple two circular waveguide modes in quadrature to a single resonant cavity in order to replicate the response of a traditional two cavity configuration using a 4-port hybrid. The 11.424 GHz, high-Q, spherical cavity has a 5.875 cm radius and is fed by the circularly polarized signal to simultaneously excite the degenerate T E114 modes. The overcoupled spherical cavity has a Q0 of 9.4 ×104 and coupling factor (β ) of 7.69 thus providing a loaded quality factor QL of 1.06 ×104 with a fill time of 150 ns. Cold tests of the polarizer demonstrated good agreement with the numerical design, showing transmission of -0.05 dB and reflection back to the input rectangular WR 90 waveguide less than -40 dB over a 100 MHz bandwidth. This novel rf pulse compressor was tested at SLAC using XL-4 Klystron that provided rf power up to 32 MW and generated peak output power of 205 MW and an average of 135 MW over the discharged signal. A general network analysis of the polarizer is discussed as well as the design and high power test of the rf pulse compressor.

  20. On the effects of quantization on mismatched pulse compression filters designed using L-p norm minimization techniques

    CSIR Research Space (South Africa)

    Cilliers, Jacques E

    2007-10-01

    Full Text Available In [1] the authors introduced a technique for generating mismatched pulse compression filters for linear frequency chirp signals. The technique minimizes the sum of the pulse compression sidelobes in a p L –norm sense. It was shown that extremely...

  1. Sub-20 fs energetic near-IR pulses generated with cascaded soliton compression in short lithium niobate crystals

    DEFF Research Database (Denmark)

    Zhou, Binbin; Chong, Andy; Wise, Frank W.;

    2011-01-01

    We show experimentally that sub-20 fs near-infrared pulses can be generated through soliton compression of energetic femtosecond pulses.e compression relies on cascaded type-0 second-harmonic generation in a just 1 mm long lithium niobate crystal....

  2. Possibility of Ion Beam Pulse Compression by X-Ray Conversion

    Science.gov (United States)

    Yabe, Takashi

    1985-02-01

    A previously proposed scheme for ion beam pulse compression is reexamined from a different viewpoint. It is shown that the criticisms made by Unterseer and Meyer-ter-Vehn are not reasonable in a real target configuration. In addition, the spherically converging effect is shown to offer further advantages.

  3. Radio frequency pulse compression experiments at SLAC (Stanford Linear Accelerator Center)

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Miller, R.H.; Nantista, C.; Spalek, G.; Wilson, P.B.

    1991-01-01

    Proposed future positron-electron linear colliders would be capable of investigating fundamental processes of interest in the 0.5--5 TeV beam-energy range. At the SLAC Linear Collider (SLC) gradient of about 20 MV/m this would imply prohibitive lengths of about 50--250 kilometers per linac. We can reduce the length by increasing the gradient but this implies high peak power, on the order of 400-- to 1000-MW at X-Band. One possible way to generate high peak power is to generate a relatively long pulse at a relatively low power and compress it into a short pulse with higher peak power. It is possible to compress before DC to RF conversion, as is done using magnetic switching for induction linacs, or after DC to RF conversion, as is done for the SLC. Using RF pulse compression it is possible to boost the 50-- to 100-MW output that has already been obtained from high-power X-Band klystrons the levels required by the linear colliders. In this note only radio frequency pulse compression (RFPC) is considered.

  4. Investigation of a pulse compression technique for medical ultrasound: a simulation study.

    Science.gov (United States)

    Rao, N A

    1994-03-01

    Pulse compression techniques that are capable of producing a large signal-to-noise (SNR) enhancement, have been used successfully in many different fields. For medical applications, frequency-dependent attenuation in soft tissue can limit the usefulness of this method. In the paper, this issue is examined through model-simulation studies. Frequency-modulation (FM) chirp, considered in the study, is just one form of pulse coding technique. Pulse propagation effects in soft tissue are modelled as a linear zero phase filter. A method to perform simulations and estimate the effective time-bandwidth product K is outlined. K describes the SNR enhancement attainable under limitations imposed by the soft-tissue medium. An effective time-bandwidth product is evaluated as a function of soft-tissue linear attenuation coefficient alpha o, scatterer depth z and the bandwidth of the interrogating FM pulse, under realistic conditions. Results indicate that, under certain conditions, K can be significantly lower than its expected value in a non-attenuating medium. It is argued that although limitations exist, pulse compression techniques can still be used to improve resolution or increase penetrational depth. The real advantage over conventional short-pulse imaging comes from the possibility that these improvements can be accomplished without increasing the peak intensity of the interrogating pulse above any threshold levels set by possible bio-effect considerations.

  5. Controlled supercontinuum generation for optimal pulse compression : a time-warp analysis of nonlinear propagation of ultra-broad-band pulses

    NARCIS (Netherlands)

    Spanner, M; Pshenichnikov, M; Olvo, [No Value; Ivanov, M

    2003-01-01

    We describe the virtues of the pump-probe approach for controlled supercontinuum generation in nonlinear media, using the example of pulse compression by cross-phase modulation in dielectrics. Optimization of a strong (pump) pulse and a weak (probe) pulse at the input into the medium opens the route

  6. A scheme of pulse compression lidar with enhanced modulated bandwidth for detection through scattering media

    Science.gov (United States)

    Yang, Cheng-hua; Zhang, Yong; Jin, Chen-fei; Xu, Lu; Yang, Xu; Wang, Qiang; Liu, Yue-hao; Zhao, Yuan

    2016-12-01

    This paper presents a scheme of pulse compression lidar with enhanced electrical modulated bandwidth. An ultra-wideband linear frequency modulated signal with a bandwidth of 50 GHz is generated using femtosecond laser and superimposed linear chirp fiber Bragg gratings in the transmitter, which separates the echo of the target from the backward scattered noise with low modulated frequency. An optical pulse compression system based on a negative dispersion fiber Bragg grating is used to compress the ultra-wideband linear frequency modulated signal in the receiver. SNR and range resolution of the proposed scheme are numerically simulated to prove its feasibility. The simulation results indicate that an enhancement of SNR by 15.8 dB can be achieved using the scheme, and the range resolution of the scheme increases from 0.68 m to 0.0027 m. It is therefore concluded that the proposed scheme is suitable for detection through scattering media.

  7. Characterization and compression of dissipative-soliton-resonance pulses in fiber lasers

    CERN Document Server

    Li, Daojing; Zhou, Junyu; Zhao, Luming; Tang, Dingyuan; Shen, Deyuan

    2016-01-01

    We report numerical and experimental studies of dissipative-soliton-resonance (DSR) in a fiber laser with a nonlinear optical loop mirror. The DSR pulse presents temporally a flat-top profile and a clamped peak power. Its spectrum has a rectangle profile with characteristic steep edges. It shows a unique behavior as pulse energy increases: The rectangle part of the spectrum is unchanged while the newly emerging spectrum sits on the center part and forms a peak. Experimental observations match well with the numerical results. Moreover, compression of the DSR pulses is both numerically and experimentally demonstrated for the first time. An experimentally obtained DSR pulse of 63 ps duration is compressed down to 760 fs, with low-intensity pedestals using a grating pair. Before being compressed to its narrowest width, the pulse firstly evolves into a cat-ear profile, and the corresponding autocorrelation trace shows a crown shape, which distinguishes itself from properties of other solitons formed in fiber laser...

  8. The fast extraction kicker for J-PARC with a novel pulse compression system

    Energy Technology Data Exchange (ETDEWEB)

    Koseki, Kunio, E-mail: kunio.koseki@kek.jp; Matsumoto, Hiroshi

    2014-03-01

    A fast extraction kicker magnet for the main ring of J-PARC has been developed. A lumped constant type magnet is employed for its structural simplicity and stability in high-voltage operation. A disadvantage of the lumped constant type, a slow rise time, was alleviated by the adoption of a newly developed magnetic pulse compression system. The effectiveness of the magnetic pulse compression system in sharpening the excitation current was confirmed both by a circuit simulation and experimentally. The newly developed fast extraction kicker system was operated successfully with a 30 kV charging voltage of the pulsed power supply. The required rise time of less than 1.1 μs was achieved in the measurement.

  9. Soliton compression to ultra-short pulses using cascaded quadratic nonlinearities in silica photonic crystal fibers

    DEFF Research Database (Denmark)

    Bache, Morten; Lægsgaard, Jesper; Bang, Ole;

    2007-01-01

    We investigate the possibility of using poled silica photonic crystal fibers for self-defocusing soliton compression with cascaded quadratic nonlinearities. Such a configuration has promise due to the desirable possibility of reducing the group-velocity mismatch. However, this unfortunately leads...... nonlinearity, and show that compression of nJ pulses to few-cycle duration is possible in such a fiber. A small amount of group-velocity mismatch optimizes the compression.......We investigate the possibility of using poled silica photonic crystal fibers for self-defocusing soliton compression with cascaded quadratic nonlinearities. Such a configuration has promise due to the desirable possibility of reducing the group-velocity mismatch. However, this unfortunately leads...

  10. On the trade-off between mainlobe width and peak sidelobe level of mismatched pulse compression filters for linear chirp waveforms

    CSIR Research Space (South Africa)

    Cilliers, Jacques E

    2009-09-01

    Full Text Available In previous paper the authors introduced a technique for generating mismatched pulse compression filters for linear frequency chirp signals. The technique minimizes the sum of the pulse compression sidelobes in an Lp norm sense. It was shown...

  11. A pulse-compression-ring circuit for high-efficiency electric propulsion.

    Science.gov (United States)

    Owens, Thomas L

    2008-03-01

    A highly efficient, highly reliable pulsed-power system has been developed for use in high power, repetitively pulsed inductive plasma thrusters. The pulsed inductive thruster ejects plasma propellant at a high velocity using a Lorentz force developed through inductive coupling to the plasma. Having greatly increased propellant-utilization efficiency compared to chemical rockets, this type of electric propulsion system may one day propel spacecraft on long-duration deep-space missions. High system reliability and electrical efficiency are extremely important for these extended missions. In the prototype pulsed-power system described here, exceptional reliability is achieved using a pulse-compression circuit driven by both active solid-state switching and passive magnetic switching. High efficiency is achieved using a novel ring architecture that recovers unused energy in a pulse-compression system with minimal circuit loss after each impulse. As an added benefit, voltage reversal is eliminated in the ring topology, resulting in long lifetimes for energy-storage capacitors. System tests were performed using an adjustable inductive load at a voltage level of 3.3 kV, a peak current of 20 kA, and a current switching rate of 15 kA/micros.

  12. Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression

    Science.gov (United States)

    Varshnay, N. K.; Singh, A.; Benerji, N. S.

    2017-02-01

    Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression suitable for material processing applications are presented here. The laser incorporates in-built compact gas circulation and gas cooling to ensure fresh gas mixture between the electrodes for repetitive operation. A magnetically coupled tangential blower is used for gas circulation inside the laser chamber for repetitive operation. The exciter consists of C-C energy transfer circuit and thyratron is used as a high-voltage main switch with single-stage magnetic pulse compression (MPC) between thyratron and the laser electrodes. Low inductance of the laser head and uniform and intense pre-ionization are the main features of the electric circuit used in the laser. A 250 ns rise time voltage pulse was compressed to 100 ns duration with a single-stage magnetic pulse compressor using Ni-Zn ferrite cores. The laser can generate about 150 mJ at ˜100 Hz rep-rate reliably from a discharge volume of 100 cm 3. 2D spatial laser beam profile generated is presented here. The profile shows that the laser beam is completely filled with flat-top which is suitable for material processing applications. The SEM image of the microhole generated on copper target is presented here.

  13. Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression

    Indian Academy of Sciences (India)

    N K VARSHNAY; A A SINGH; N S BENERJI

    2017-02-01

    Performance characteristics of an excimer laser (XeCl) with single-stage magnetic pulse compression suitable for material processing applications are presented here. The laser incorporates in-built compact gas circulation and gas cooling to ensure fresh gas mixture between the electrodes for repetitive operation. A magnetically coupled tangential blower is used for gas circulation inside the laser chamber for repetitive operation. The exciter consists of C–C energy transfer circuit and thyratron is used as a high-voltage main switch with singlestage magnetic pulse compression (MPC) between thyratron and the laser electrodes. Low inductance of the laser head and uniform and intense pre-ionization are the main features of the electric circuit used in the laser. A 250 ns rise time voltage pulse was compressed to 100 ns duration with a single-stage magnetic pulse compressor using Ni–Zn ferrite cores. The laser can generate about 150 mJ at ∼100 Hz rep-rate reliably from a discharge volumeof 100 cm$^3$. 2D spatial laser beam profile generated is presented here. The profile shows that the laser beam is completely filled with flat-top which is suitable for material processing applications. The SEM image of the microhole generated on copper target is presented here.

  14. Parameter optimization of pulse compression in ultrasound imaging systems with coded excitation.

    Science.gov (United States)

    Behar, Vera; Adam, Dan

    2004-08-01

    A linear array imaging system with coded excitation is considered, where the proposed excitation/compression scheme maximizes the signal-to-noise ratio (SNR) and minimizes sidelobes at the output of the compression filter. A pulse with linear frequency modulation (LFM) is used for coded excitation. The excitation/compression scheme is based on the fast digital mismatched filtering. The parameter optimization of the excitation/compression scheme includes (i) choice of an optimal filtering function for the mismatched filtering; (ii) choice of an optimal window function for tapering of the chirp amplitude; (iii) optimization of a chirp-to-transducer bandwidth ratio; (iv) choice of an appropriate n-bit quantizer. The simulation results show that the excitation/compression scheme can be implemented as a Dolph-Chebyshev filter including amplitude tapering of the chirp with a Lanczos window. An example of such an optimized system is given where the chirp bandwidth is chosen to be 2.5 times the transducer bandwidth and equals 6 MHz: The sidelobes are suppressed to -80 dB, for a central frequency of 4 MHz, and to -94 dB, for a central frequency of 8 MHz. The corresponding improvement of the SNR is 18 and 21 dB, respectively, when compared to a conventional short pulse imaging system. Simulation of B-mode images demonstrates the advantage of coded excitation systems of detecting regions with low contrast.

  15. Performance characteristics of an induction linac magnetic pulse compression modulator at multi-kilohertz pulse repetition frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Sampayan, S.E.; Chambers, F.W.; Deadrick, F.J. [and others

    1991-05-01

    The ETA-II linear induction accelerator utilizes four pulse power conditioning chains. Magnetic pulse compression modulators (MAG1-Ds) form the last stage of each chain. A single power conditioning chain is used to drive the injector; the remaining three are used to drive 60 accelerator cells. Nominal parameters of the MAG1-D are an output voltage of greater than 120 kV, pulse width of 70 ns, and an output impedance of 2 ohms. Our operations goal for ETA-II is stable high average power operation at 5 kHz PRF. We have begun upgrading and characterizing the power conditioning chain on our High Average Power Test Stand (HAPTS). On HAPTS, the pulse to pulse amplitude stability has been improved to less than 0.7% (one sigma) and of order 3-5 ns random jitter about a systematic timing variation. In this paper we describe the status of our work to achieve the this paper we describe the status of our work to achieve the average power operation of ETA-II

  16. Compressive sensing reconstruction of feed-forward connectivity in pulse-coupled nonlinear networks

    Science.gov (United States)

    Barranca, Victor J.; Zhou, Douglas; Cai, David

    2016-06-01

    Utilizing the sparsity ubiquitous in real-world network connectivity, we develop a theoretical framework for efficiently reconstructing sparse feed-forward connections in a pulse-coupled nonlinear network through its output activities. Using only a small ensemble of random inputs, we solve this inverse problem through the compressive sensing theory based on a hidden linear structure intrinsic to the nonlinear network dynamics. The accuracy of the reconstruction is further verified by the fact that complex inputs can be well recovered using the reconstructed connectivity. We expect this Rapid Communication provides a new perspective for understanding the structure-function relationship as well as compressive sensing principle in nonlinear network dynamics.

  17. Compressive sensing reconstruction of feed-forward connectivity in pulse-coupled nonlinear networks.

    Science.gov (United States)

    Barranca, Victor J; Zhou, Douglas; Cai, David

    2016-06-01

    Utilizing the sparsity ubiquitous in real-world network connectivity, we develop a theoretical framework for efficiently reconstructing sparse feed-forward connections in a pulse-coupled nonlinear network through its output activities. Using only a small ensemble of random inputs, we solve this inverse problem through the compressive sensing theory based on a hidden linear structure intrinsic to the nonlinear network dynamics. The accuracy of the reconstruction is further verified by the fact that complex inputs can be well recovered using the reconstructed connectivity. We expect this Rapid Communication provides a new perspective for understanding the structure-function relationship as well as compressive sensing principle in nonlinear network dynamics.

  18. Beam dynamics analysis in pulse compression using electron beam compact simulator for Heavy Ion Fusion

    Directory of Open Access Journals (Sweden)

    Kikuchi Takashi

    2013-11-01

    Full Text Available In a final stage of an accelerator system for heavy ion inertial fusion (HIF, pulse shaping and beam current increase by bunch compression are required for effective pellet implosion. A compact simulator with an electron beam was constructed to understand the beam dynamics. In this study, we investigate theoretically and numerically the beam dynamics for the extreme bunch compression in the final stage of HIF accelerator complex. The theoretical and numerical results implied that the compact experimental device simulates the beam dynamics around the stagnation point for initial low temperature condition.

  19. Adaptive pulse compression for transform-limited 15-fs high-energy pulse generation.

    Science.gov (United States)

    Zeek, E; Bartels, R; Murnane, M M; Kapteyn, H C; Backus, S; Vdovin, G

    2000-04-15

    We demonstrate the use of a deformable-mirror pulse shaper, combined with an evolutionary optimization algorithm, to correct high-order residual phase aberrations in a 1-mJ, 1-kHz, 15-fs laser amplifier. Frequency-resolved optical gating measurements reveal that the output pulse duration of 15.2 fs is within our measurement error of the theoretical transform limit. This technique significantly reduces the pulse duration and the temporal prepulse energy of the pulse while increasing the peak intensity by 26%. It is demonstrated, for what is believed to be the first time, that the problem of pedestals in laser amplifiers can be addressed by spectral-domain correction.

  20. Adaptive pulse compression for transform-limited 15-fs high-energy pulse generation

    Energy Technology Data Exchange (ETDEWEB)

    Zeek, E.; Bartels, R.; Murnane, M. M.; Kapteyn, H. C.; Backus, S.; Vdovin, G.

    2000-04-15

    We demonstrate the use of a deformable-mirror pulse shaper, combined with an evolutionary optimization algorithm, to correct high-order residual phase aberrations in a 1-mJ, 1-kHz, 15-fs laser amplifier. Frequency-resolved optical gating measurements reveal that the output pulse duration of 15.2 fs is within our measurement error of the theoretical transform limit. This technique significantly reduces the pulse duration and the temporal prepulse energy of the pulse while increasing the peak intensity by 26%. It is demonstrated, for what is believed to be the first time, that the problem of pedestals in laser amplifiers can be addressed by spectral-domain correction. (c) 2000 Optical Society of America.

  1. Pulse Compression Based on Laser-Induced Optical Breakdown in Suspension

    Institute of Scientific and Technical Information of China (English)

    HASI Wu-Li-Ji; FU Mei-Ling; LU Huan-Huan; GONG Sheng; LU Zhi-Wei; LIN Dian-Yang; HE Wei-Ming

    2009-01-01

    Pulse compression based on laser-induced optical breakdown in suspension is investigated.The physical mechanism behind it is analyzed theoretically and validated in the Q-switched Nd:YAG laser system.A 12-ns pump pulse is suppressed to 5 ns with good fidelity in the front edge and sharp steepness in the trailing edge.The HT-270,which has a small gain coemcient and absorption coefficient,is used as a solvent,and therefore the disturbance induced by stimulated Brillouin scattering and absorption are minimized and the transmittivity is enhanced.

  2. Compression of fiber supercontinuum pulses to the Fourier-limit in a high-numerical-aperture focus

    DEFF Research Database (Denmark)

    Tu, Haohua; Liu, Yuan; Turchinovich, Dmitry

    2011-01-01

    A multiphoton intrapulse interference phase scan (MIIPS) adaptively and automatically compensates the combined phase distortion from a fiber supercontinuum source, a spatial light modulator pulse shaper, and a high-NA microscope objective, allowing Fourier-transform-limited compression...... of the supercontinuum pulses at the focus of the objective. A second-harmonic-generation-based method is employed to independently validate the transform-limited compression. The compressed pulses at the focus of the objective have a tunable duration of 10:8–38:9 fs (FWHM), a central wavelength of ∼1020nm, an average...

  3. Analysis of LAPAN-IPB image lossless compression using differential pulse code modulation and huffman coding

    Science.gov (United States)

    Hakim, P. R.; Permala, R.

    2017-01-01

    LAPAN-A3/IPB satellite is the latest Indonesian experimental microsatellite with remote sensing and earth surveillance missions. The satellite has three optical payloads, which are multispectral push-broom imager, digital matrix camera and video camera. To increase data transmission efficiency, the multispectral imager data can be compressed using either lossy or lossless compression method. This paper aims to analyze Differential Pulse Code Modulation (DPCM) method and Huffman coding that are used in LAPAN-IPB satellite image lossless compression. Based on several simulation and analysis that have been done, current LAPAN-IPB lossless compression algorithm has moderate performance. There are several aspects that can be improved from current configuration, which are the type of DPCM code used, the type of Huffman entropy-coding scheme, and the use of sub-image compression method. The key result of this research shows that at least two neighboring pixels should be used for DPCM calculation to increase compression performance. Meanwhile, varying Huffman tables with sub-image approach could also increase the performance if on-board computer can support for more complicated algorithm. These results can be used as references in designing Payload Data Handling System (PDHS) for an upcoming LAPAN-A4 satellite.

  4. High-contrast linear optical pulse compression using a temporal hologram.

    Science.gov (United States)

    Li, Bo; Fernández-Ruiz, Maria R; Lou, Shuqin; Azaña, José

    2015-03-01

    Temporal holograms can be realized by temporal amplitude-only modulation devices and used for generation and processing of complex (amplitude and phase) time-domain signals. Based on the temporal hologram concept, we numerically and experimentally demonstrate a novel design for linear optical pulse compression using temporal modulation of continuous-wave light combined with dispersion. The newly introduced scheme overcomes the undesired background problem that is intrinsic to designs based on temporal zone plates, while also offering an energy efficiency of ~25%. This pulse compression scheme can ideally provide an arbitrarily high time-bandwidth product using a low peak-power modulation driving signal, though in practice it is limited by the achievable modulation bandwidth and dispersion amount.

  5. Post-compression of high energy terawatt-level femtosecond pulses and application to high order harmonic generation

    CERN Document Server

    Hort, Ondřej; Cabasse, Amélie; Petit, Stéphane; Mével, Eric; Descamps, Dominique; Constant, Eric

    2015-01-01

    We perform a post-compression of high energy pulses by using optical-field ionization of low pressure helium gas in a guided geometry. We apply this approach to a TW chirped-pulse-amplification based Ti:Sapphire laser chain and show that spectral broadening can be controlled both with the input pulse energy and gas pressure. Under optimized conditions, we generate 10 fs pulses at TW level directly under vacuum and demonstrate a high stability of the post compressed pulse duration. These high energy post-compressed pulses are thereafter used to perform high harmonic generation in a loose focusing geometry. The XUV beam is characterized both spatially and spectrally on a single shot basis and structured continuous XUV spectra are observed.

  6. Generation, shaping, compression, characterization and application of intense ultrashort laser pulses

    CERN Document Server

    Cheng, Z

    2001-01-01

    Recently, the development of intense ultrashort laser pulses has attracted much interest because of their significant applications in many fields of science and technology. This thesis contributes to the generation, shaping, compression, characterization and application of intense ultrashort laser pulses as follows: 1. Laser pulses of 17.5-fs with a peak power of 0.1-TW at 1-kHz repetition rate have been generated by a compact single-stage ten-pass Ti:sapphire amplifier system with a high-order-dispersion-mirror compensator and a spectral shaping for the first time. The experimental results are in reasonable agreement with numerical calculations. 2. The first experimental study on arbitrary shaping of intense ultrashort pulses has been conducted in a kHz amplifier system capable of generating 27 fs pulses by using an acousto-optic programmable dispersive filter (AOPDF). 17-fs transform-limited pulses have been achieved and arbitrary shaping of these 17-fs pulses has been demonstrated both in the temporal and ...

  7. An exploding foil shockwave technique for magnetic flux compression and high voltage pulse generation

    CERN Document Server

    Goh, S E

    2002-01-01

    This thesis describes a novel electromagnetic shockwave technique for use in compressing magnetic flux and to serve as the basis for a new approach to producing fast-rising voltage pulses with amplitudes of several hundred kV. The shockwave is produced by an exploding foil driven electric gun that accelerates a Mylar flyer to impact with a sample of aluminium powder. Both Japanese and Russian researchers have previously published experimental results for shockwave magnetic flux compression using an explosive driver. The present research considers replacing the explosive energy of this driver by the electrostatic energy stored in a capacitor bank, thereby enabling experiments to be performed in a laboratory environment. Differences in performance that arise from the use of explosive and electrical driver are examined. A conventional electric gun system in planar geometry is developed to study the insulator-to-metallic transition in shock-compressed aluminium powder. This provides data on the conducting shock f...

  8. Cylindrical shockwave-induced compression mechanism in femtosecond laser Bessel pulse micro-drilling of PMMA

    Science.gov (United States)

    Wang, Guoyan; Yu, Yanwu; Jiang, Lan; Li, Xiaowei; Xie, Qian; Lu, Yongfeng

    2017-04-01

    Femtosecond (fs) laser Bessel pulses can be employed for high-quality and high-speed fabrication of high-aspect-ratio uniform microhole arrays. This technique exhibits prominent potential in three-dimensional packaging, fluidic devices, fiber sensing, biomedical devices, and aeronautics. However, the fundamental mechanisms remain mysterious. Using the femtosecond time-resolved pump-probe shadowgraph technique, this study revealed that the generation of cylindrical shockwaves inside the bulk material and the corresponding compression mechanism play key roles in the formation of high-aspect-ratio microholes. The phenomena were observed in all experiments of Bessel beam drilling of polymethyl methacrylate. In the aforementioned cases, the compression mechanism was confirmed by measuring sample mass losses that were experimentally determined to be negligible. By contrast, neither cylindrical shockwave nor compression mechanism was observed when a fused silica or Gaussian laser beam was involved.

  9. Generation, compression, and propagation of pulse trains in the nonlinear Schrödinger equation with distributed coefficients.

    Science.gov (United States)

    Wang, Luyun; Li, Lu; Li, Zhonghao; Zhou, Guosheng; Mihalache, Dumitru

    2005-09-01

    The generalized nonlinear Schrödinger model with distributed dispersion, nonlinearity, and gain or loss is considered and the explicit, analytical solutions describing the dynamics of bright solitons on a continuous-wave background are obtained in quadratures. Then, the generation, compression, and propagation of pulse trains are discussed in detail. The numerical results show that solitons can be compressed by choosing the appropriate control fiber system, and pulse trains generated by modulation instability can propagate undistorsted along fibers with distributed parameters by controlling appropriately the energy of each pulse in the pulse train.

  10. Efficacy and safety of long-pulse pulsed dye laser delivered with compression versus cryotherapy for treatment of solar lentigines

    Directory of Open Access Journals (Sweden)

    Hassan Seirafi

    2011-01-01

    Full Text Available Background: Although cryotherapy is still the first-line therapy for solar lentigines, because of the side effects such as post-inflammatory hyperpigmentation (PIH, especially in patients with darker skin types, pigment-specific lasers should be considered as a therapy for initial treatment. Aim: The aim of this study is to evaluate the efficacy and safety of cryotherapy compared with 595-nm pulsed dye laser (PDL with cutaneous compression in the treatment of solar lentigines. Materials and Methods: Twenty-two patients (skin type II−IV with facial or hand lentigines participated in this study. Lesions of one side of the face or each hand were randomly assigned and treated with either cryotherapy or PDL. Treatments were performed with radiant exposures of 10 J/cm 2 , 7-mm spot size and 1.5 ms pulse duration with no epidermal cooling. Photographs were taken before treatment and 1-month later. The response rate and side effects were compared. Results: PDL was more likely to produce substantial lightening of the solar lentigines than cryotherapy, especially in skin type III and IV (n = 8, n = 9; P 0.05. PIH was seen only in cryotherapy group. PDL group had only minimal erythema. No purpura was observed. Conclusion: PDL with compression is superior to cryotherapy in the treatment of solar lentigines in darker skin types.

  11. Enhanced pulse compression induced by the interaction between the third-order dispersion and the cross-phase modulation in birefringent fibres

    Institute of Scientific and Technical Information of China (English)

    徐文成; 陈伟成; 张书敏; 罗爱平; 刘颂豪

    2002-01-01

    In this paper, we report on the enhanced pulse compression due to the interaction between the positive third-order dispersion (TOD) and the nonlinear effect (cross-phase modulation effect) in birefringent fibres. Polarization soliton compression along the slow axis can be enhanced in a birefringent fibre with positive third-order dispersion. while the polarization soliton compression along the fast axis can be enhanced in the fibre with negative third-order dispersion.Moreover, there is an optimal third-order dispersion parameter for obtaining the optimal pulse compression.Redshifted initial chirp is helpful to the pulse compression, while blueshifted chirp is detrimental to the pulse compression. There is also an optimal chirp parameter to reach maximum pulse compression. The optimal pulse compression for TOD parameters under different N-order solitons is also found.

  12. Nonlinear optical compression of high-power 10-μm CO2 laser pulses in gases and semiconductors

    Science.gov (United States)

    Pigeon, Jeremy; Tochitsky, Sergei; Joshi, Chan

    2017-03-01

    We review a series of experiments on nonlinear optical compression of high-power, picosecond, 10-µm CO2 laser pulses. Presented schemes include self-phase modulation in a Xe-filled hollow glass waveguide, self-phase modulation in GaAs followed by compression, and multiple four-wave mixing compression of a laser beat-wave in GaAs. The novel nonlinear optics and technical challenges uncovered through these experiments are discussed.

  13. Pulsed Compression for Aerosol Ranging with Coherent Pulse-Doppler Lidar Systems

    Science.gov (United States)

    1990-12-01

    generation technique requires an impulse function or short time duration pulse as the input to a dispersive phase filter . The frequency transfer...function H(f) of the dispersive phase filter can be expressed in general as H(f) = IH(f)Iexp lU(f)] (122) where the magnitude of the transfer function IH(f...response of the dispersive phase filter to a short time duration signal with large bandwidth B is a long time duration signal with the bandwidth B of

  14. Developing The Physics Desing for NDCS-II, A Unique Pulse-Compressing Ion Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, A; Barnard, J J; Cohen, R H; Grote, D P; Lund, S M; Sharp, W M; Faltens, A; Henestroza, E; Jung, J; Kwan, J W; Lee, E P; Leitner, M A; Logan, B G; Vay, J -; Waldron, W L; Davidson, R C; Dorf, M; Gilson, E P; Kaganovich, I

    2009-09-24

    The Heavy Ion Fusion Science Virtual National Laboratory (a collaboration of LBNL, LLNL, and PPPL) is using intense ion beams to heat thin foils to the 'warm dense matter' regime at {approx}< 1 eV, and is developing capabilities for studying target physics relevant to ion-driven inertial fusion energy. The need for rapid target heating led to the development of plasma-neutralized pulse compression, with current amplification factors exceeding 50 now routine on the Neutralized Drift Compression Experiment (NDCX). Construction of an improved platform, NDCX-II, has begun at LBNL with planned completion in 2012. Using refurbished induction cells from the Advanced Test Accelerator at LLNL, NDCX-II will compress a {approx}500 ns pulse of Li{sup +} ions to {approx} 1 ns while accelerating it to 3-4 MeV over {approx} 15 m. Strong space charge forces are incorporated into the machine design at a fundamental level. We are using analysis, an interactive 1D PIC code (ASP) with optimizing capabilities and centroid tracking, and multi-dimensional Warpcode PIC simulations, to develop the NDCX-II accelerator. This paper describes the computational models employed, and the resulting physics design for the accelerator.

  15. Proceedings of the first JAERI-Kansai international workshop on ultrashort-pulse ultrahigh-power lasers and simulation for laser-plasma interactions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Records of the First JAERI-Kansai International Workshop, which focused on the subject of `Ultrashort-Pulse Ultrahigh-Power Lasers and Simulation for Laser-Plasma Interactions`, are contained in this issue. The First JAERI-Kansai International Workshop was held as Joint ICFA/JAERI-Kansai International Workshop `97 with International Committee for Future Accelerators (ICFA). This report consists of 24 contributed papers. (J.P.N.)

  16. Self-compression of femtosecond pulses in argon with a power close to the self-focusing threshold

    Institute of Scientific and Technical Information of China (English)

    Chen Xiao-Wei; Zeng Zhi-Nan; Dai Jun; Li Xiao-Fang; Li Ru-Xin; Xu Zhi-Zhan

    2008-01-01

    Self-compression of femtosecond pulses in noble gases with an input power close to the self-focusing threshold has been investigated experimentally and theoretically.It is demonstrated that either multiphoton ionization (MPI) or space-time focusing and self-steepening effects can induce pulse shortening,but they predominate at different beam intensities during the propagation.The latter effects play a key role in the final pulse self-compression.By choosing an appropriate focusing parameter,action distance of the space-time focusing and self-steepening effects can be lengthened,which can promote a shock pulse structure with a duration as short as two optical cycles.It is also found that,for our calculation eases in which an input pulse power is close to the self-focusing threshold,either group velocity dispersion(GVD) or multiphoton absorption (MPA) has a negligible influence on pulse characteristics in the propagation process.

  17. Efficient Spectral Broadening in the 100-W Average Power Regime Using Gas Filled Kagome HC-PCF and Pulse Compression

    CERN Document Server

    Emaury, Florian; Debord, Benoit; Ghosh, Debashri; Diebold, Andreas; Gerome, Frederic; Suedmeyer, Thomas; Benabid, Fetah; Keller, Ursula

    2014-01-01

    We present nonlinear pulse compression of a high-power SESAM-modelocked thin-disk laser (TDL) using an Ar-filled hypocycloid-core Kagome Hollow-Core Photonic Crystal Fiber (HC-PCF). The output of the modelocked Yb:YAG TDL with 127 W average power, a pulse repetition rate of 7 MHz, and a pulse duration of 740 fs was spectrally broadened 16-fold while propagating in a Kagome HC-PCF containing 13 bar of static Argon gas. Subsequent compression tests performed using 8.4% of the full available power resulted in a pulse duration as short as 88 fs using the spectrally broadened output from the fiber. Compressing the full transmitted power through the fiber (118 W) could lead to a compressed output of >100 W of average power and >100 MW of peak power with an average power compression efficiency of 88%. This simple laser system with only one ultrafast laser oscillator and a simple single-pass fiber pulse compressor, generating both high peak power >100 MW and sub-100-fs pulses at megahertz repetition rate, is very int...

  18. Terawatt-level few-cycle mid-IR pulses through nonlinear self-compression in bulk

    CERN Document Server

    Shumakova, V; Ališauskas, S; Zheltikov, A Voronin A M; Faccio, D; Kartashov, D; Baltuška, A; Pugžlys, A

    2015-01-01

    The physics of strong-field applications requires driver laser pulses that are both energetic and extremely short. Whereas optical amplifiers, laser and parametric, boost the energy, their gain bandwidth restricts the attainable pulse duration, requiring additional nonlinear spectral broadening to enable few or even single cycle compression and a corresponding peak power increase. In the mid-IR wavelength range that is critically important for scaling the ponderomotive energy in strong-field interactions, we demonstrate a remarkably simple energy-efficient and scalable soliton-like pulse compression in a mm-long YAG crystal with no additional dispersion management. Sub-three-cycle pulses with >0.65 TW peak power are compressed and extracted before the onset of modulation instability and multiple filamentation as a result of a favorable interplay between strong anomalous dispersion and optical nonlinearity around the wavelength of 3900 nm. As a striking manifestation of the increased peak power, we show the ev...

  19. Proceedings of the workshop on ion source issues relevant to a pulsed spallation neutron source: Part 1: Workshop summary

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, L.; Leung, K.N.; Alonso, J. [eds.

    1994-10-01

    The workshop reviewed the ion-source requirements for high-power accelerator-driven spallation neutron facilities, and the performance of existing ion sources. Proposals for new facilities in the 1- to 5-MW range call for a widely differing set of ion-source requirements. For example, the source peak current requirements vary from 40 mA to 150 mA, while the duty factor ranges from 1% to 9%. Much of the workshop discussion centered on the state-of-the-art of negative hydrogen ion source (H{sup {minus}}) technology and the present experience with Penning and volume sources. In addition, other ion source technologies, for positive ions or CW applications were reviewed. Some of these sources have been operational at existing accelerator complexes and some are in the source-development stage on test stands.

  20. Experimental studies of high order soliton compression effect and gain characteristics in femtosecond laser pulses Er3+-doped fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    刘东峰; 陈国夫; 白晋涛; 王贤华

    2000-01-01

    Seed laser pulses with average power of 146 pW and pulse duration of 480 fs were amplified to 14.5 mW. The pulse duration was compressed to 260 fs using 6 m high concentration Er3+ -doped fiber under forward pumping. The amplified signal pulse energy was 0.691 nJ (corresponding to a peak power of 2 657.7 W) and the repetition rate was 20.84 MHz. Spectrum breakup was observed simultaneously. The spectrum of pulses amplified by 3 m Er3+ -doped fiber remains a single peak under different pump power. The amplified pulse duration was compressed abnormally with the increasing pump power using the backward pumping; that is, the amplified pulses were compressed with the increasing pump power under low pump power. When the pump power reached 38 mW, the shortest amplified pulse duration was 309 fs. With further increase in pump power, the amplified pulses began broadening, accompanied by a single peak spectrum under different pump power.

  1. Application of magnetic pulse compression to the grid system of the ETA/ATA accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Birx, D.L.; Cook, E.G.; Reginato, L.L.; Schmidt, J.A.; Smith, M.W.

    1982-11-02

    During the past year, several magnetic pulse compression systems have been built and applied to the ETA accelerator. In view of their excellent performance, a non-linear magnetic system has been adopted for the ATA grid drive in place of the spark gap driven Blumlein. The magnetic system will give us a much higher reliability and greater flexibility by being independent of the high pressure gas blown system. A further advantage of this system will be the capability of achieving higher rep-rates in case of a future upgrade. System design and performance under burst mode will be described.

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

    Science.gov (United States)

    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.

  3. Generation of stable subfemtosecond hard x-ray pulses with optimized nonlinear bunch compression

    Directory of Open Access Journals (Sweden)

    Senlin Huang

    2014-12-01

    Full Text Available In this paper, we propose a simple scheme that leverages existing x-ray free-electron laser hardware to produce stable single-spike, subfemtosecond x-ray pulses. By optimizing a high-harmonic radio-frequency linearizer to achieve nonlinear compression of a low-charge (20 pC electron beam, we obtain a sharp current profile possessing a few-femtosecond full width at half maximum temporal duration. A reverse undulator taper is applied to enable lasing only within the current spike, where longitudinal space charge forces induce an electron beam time-energy chirp. Simulations based on the Linac Coherent Light Source parameters show that stable single-spike x-ray pulses with a duration less than 200 attoseconds can be obtained.

  4. Wave Mode Discrimination of Coded Ultrasonic Guided Waves Using Two-Dimensional Compressed Pulse Analysis.

    Science.gov (United States)

    Malo, Sergio; Fateri, Sina; Livadas, Makis; Mares, Cristinel; Gan, Tat-Hean

    2017-07-01

    Ultrasonic guided waves testing is a technique successfully used in many industrial scenarios worldwide. For many complex applications, the dispersive nature and multimode behavior of the technique still poses a challenge for correct defect detection capabilities. In order to improve the performance of the guided waves, a 2-D compressed pulse analysis is presented in this paper. This novel technique combines the use of pulse compression and dispersion compensation in order to improve the signal-to-noise ratio (SNR) and temporal-spatial resolution of the signals. The ability of the technique to discriminate different wave modes is also highlighted. In addition, an iterative algorithm is developed to identify the wave modes of interest using adaptive peak detection to enable automatic wave mode discrimination. The employed algorithm is developed in order to pave the way for further in situ applications. The performance of Barker-coded and chirp waveforms is studied in a multimodal scenario where longitudinal and flexural wave packets are superposed. The technique is tested in both synthetic and experimental conditions. The enhancements in SNR and temporal resolution are quantified as well as their ability to accurately calculate the propagation distance for different wave modes.

  5. Sub-Nyquist sampling and detection in Costas coded pulse compression radars

    Science.gov (United States)

    Hanif, Adnan; Mansoor, Atif Bin; Imran, Ali Shariq

    2016-12-01

    Modern pulse compression radar involves digital signal processing of high bandwidth pulses modulated with different coding schemes. One of the limiting factors in the radar's design to achieve desired target range and resolution is the need of high rate analog-to-digital (A/D) conversion fulfilling the Nyquist sampling criteria. The high sampling rates necessitate huge storage capacity, more power consumption, and extra processing requirement. We introduce a new approach to sample wideband radar waveform modulated with Costas sequence at a sub-Nyquist rate based upon the concept of compressive sensing (CS). Sub-Nyquist measurements of Costas sequence waveform are performed in an analog-to-information (A/I) converter based upon random demodulation replacing traditional A/D converter. The novel work presents an 8-order Costas coded waveform with sub-Nyquist sampling and its reconstruction. The reconstructed waveform is compared with the conventionally sampled signal and depicts high-quality signal recovery from sub-Nyquist sampled signal. Furthermore, performance of CS-based detections after reconstruction are evaluated in terms of receiver operating characteristic (ROC) curves and compared with conventional Nyquist-rate matched filtering scheme.

  6. Generating energetic few-cycle pulses at 800 nm using soliton compression with type 0 cascaded quadratic interaction in lithium niobate

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin; Chong, A.

    2010-01-01

    We show that ultra-short few-cycle pulses can be generated through soliton compression of energetic femtosecond pulses from a Ti:Sapphire regenerative amplifier. The compression relies on cascaded type 0 second-harmonic generation in mm-length lithium niobate crystals.......We show that ultra-short few-cycle pulses can be generated through soliton compression of energetic femtosecond pulses from a Ti:Sapphire regenerative amplifier. The compression relies on cascaded type 0 second-harmonic generation in mm-length lithium niobate crystals....

  7. Generating energetic few-cycle pulses at 800 nm using soliton compression with type 0 cascaded quadratic interaction in lithium niobate

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin; Chong, A.

    2010-01-01

    We show that ultra-short few-cycle pulses can be generated through soliton compression of energetic femtosecond pulses from a Ti:Sapphire regenerative amplifier. The compression relies on cascaded type 0 second-harmonic generation in mm-length lithium niobate crystals.......We show that ultra-short few-cycle pulses can be generated through soliton compression of energetic femtosecond pulses from a Ti:Sapphire regenerative amplifier. The compression relies on cascaded type 0 second-harmonic generation in mm-length lithium niobate crystals....

  8. Nonlinear compression of high energy fiber amplifier pulses in air-filled hypocycloid-core Kagome fiber.

    Science.gov (United States)

    Guichard, Florent; Giree, Achut; Zaouter, Yoann; Hanna, Marc; Machinet, Guillaume; Debord, Benoît; Gérôme, Frédéric; Dupriez, Pascal; Druon, Frédéric; Hönninger, Clemens; Mottay, Eric; Benabid, Fetah; Georges, Patrick

    2015-03-23

    We report on the generation of 34 fs and 50 µJ pulses from a high energy fiber amplifier system with nonlinear compression in an air-filled hypocycloid-core Kagome fiber. The unique properties of such fibers allow bridging the gap between solid core fibers-based and hollow capillary-based post-compression setups, thereby operating with pulse energies obtained with current state-of-the-art fiber systems. The overall transmission of the compression setup is over 70%. Together with Yb-doped fiber amplifier technologies, Kagome fibers therefore appear as a promising tool for efficient generation of pulses with durations below 50 fs, energies ranging from 10 to several hundreds of µJ, and high average powers.

  9. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiquan [Stanford Univ., CA (United States)

    2008-12-01

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  10. Pulse compression below 40fs at 1μm: The first step towards a short-pulse, high-energy beam line at LULI

    Science.gov (United States)

    Chen, Xiaowei; Zou, Jiping; Martin, Luc; Simon, Francois; Lopez-Martens, Rodrigo; Audebert, Patrick

    2010-08-01

    We present the upgrading project ELFIE (Equipement Laser de Forte Intensité et Energie) based on the "100TW" mixed Nd:glass CPA laser system at 1μm at LULI, which includes an energy enhancement and the development of a short-pulse, high-energy, good temporal contrast beam line (50fs/5J). We report the first experimental step towards the short-pulse, high-energy beam line: spectral broadening above 60nm from 7nm and temporal pulse compression below 40fs from 300fs at 1μm through a Krypton-filled hollow fiber compressor.

  11. Ion acceleration by petawatt class laser pulses and pellet compression in a fast ignition scenario

    Energy Technology Data Exchange (ETDEWEB)

    Benedetti, C. [Dipartimento di Fisica, Universita di Bologna, INFN sezione di Bologna (Italy)], E-mail: benedetti@bo.infn.it; Londrillo, P. [Dipartimento di Astronomia, Universita di Bologna, INAF sezione di Bologna, INFN sezione di Bologna (Italy); Liseykina, T.V. [Institute for Computational Technologies, SD-RAS, Novosibirsk (Russian Federation); Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Macchi, A. [polyLAB, CNR-INFM, Pisa (Italy); Sgattoni, A.; Turchetti, G. [Dipartimento di Fisica, Universita di Bologna, INFN sezione di Bologna (Italy)

    2009-07-11

    Ion drivers based on standard acceleration techniques have faced up to now several difficulties. We consider here a conceptual alternative to more standard schemes, such as HIDIF (Heavy Ion Driven Inertial Fusion), which are still beyond the present state of the art of particle accelerators, even though the requirements on the total beam energy are lowered by fast ignition scenarios. The new generation of petawatt class lasers open new possibilities: acceleration of electrons or protons for the fast ignition and eventually light or heavy ions acceleration for compression. The pulses of chirped pulse amplification (CPA) lasers allow ions acceleration with very high efficiency at reachable intensities (I{approx}10{sup 21}W/cm{sup 2}), if circularly polarized light is used since we enter in the radiation pressure acceleration (RPA) regime. We analyze the possibility of accelerating carbon ion bunches by interaction of a circularly polarized pulses with an ultra-thin target. The advantage would be compactness and modularity, due to identical accelerating units. The laser efficiency required to have an acceptable net gain in the inertial fusion process is still far from the presently achievable values both for CPA short pulses and for long pulses used for direct illumination. Conversely the energy conversion efficiency from the laser pulse to the ion bunch is high and grows with the intensity. As a consequence the energy loss is not the major concern. For a preliminary investigation of the ions bunch production we have used the PIC code ALaDyn developed to analyze the results of the INFN-CNR PLASMONX experiment at Frascati National Laboratories (Rome, Italy) where the 0.3 PW laser FLAME will accelerate electrons and protons. We present the results of some 1D simulations and parametric scan concerning the acceleration of carbon ions that we suppose to be fully ionized. Circularly polarized laser pulses of 50 J and 50-100 fs duration, illuminating a 100{mu}m{sup 2} area

  12. Method based on broadband compressed pulse superposition to measure properties of underwater acoustic materials

    Institute of Scientific and Technical Information of China (English)

    LI Shui; MIAO Rongxing

    2001-01-01

    A method is proposed for the measurements of the performances of underwater acoustic finite sized large area material samples in a free field by using broadband pulse compression technique. As the result of which, the low-frequency cutoff of the standard tests is obviously reduced, and the broadband measurements are also realized. The experimental system provides measurements of complex reflection and transmission coefficients at continuous frequency points. From the data one can obtain the following acoustic parameters: echo reduction and insertion loss, absorption and attenuation coefficients, etc. The measurements are performed for two actual panels with the size 1 m×1 m in the frequency range from 2-20 kHz.

  13. Analysis of Doppler Effect on the Pulse Compression of Different Codes Emitted by an Ultrasonic LPS

    Directory of Open Access Journals (Sweden)

    Jorge Morera

    2011-11-01

    Full Text Available This work analyses the effect of the receiver movement on the detection by pulse compression of different families of codes characterizing the emissions of an Ultrasonic Local Positioning System. Three families of codes have been compared: Kasami, Complementary Sets of Sequences and Loosely Synchronous, considering in all cases three different lengths close to 64, 256 and 1,024 bits. This comparison is first carried out by using a system model in order to obtain a set of results that are then experimentally validated with the help of an electric slider that provides radial speeds up to 2 m/s. The performance of the codes under analysis has been characterized by means of the auto-correlation and cross-correlation bounds. The results derived from this study should be of interest to anyone performing matched filtering of ultrasonic signals with a moving emitter/receiver.

  14. Analysis of Doppler effect on the pulse compression of different codes emitted by an ultrasonic LPS.

    Science.gov (United States)

    Paredes, José A; Aguilera, Teodoro; Alvarez, Fernando J; Lozano, Jesús; Morera, Jorge

    2011-01-01

    This work analyses the effect of the receiver movement on the detection by pulse compression of different families of codes characterizing the emissions of an ultrasonic local positioning system. Three families of codes have been compared: Kasami, Complementary Sets of Sequences and Loosely Synchronous, considering in all cases three different lengths close to 64, 256 and 1,024 bits. This comparison is first carried out by using a system model in order to obtain a set of results that are then experimentally validated with the help of an electric slider that provides radial speeds up to 2 m/s. The performance of the codes under analysis has been characterized by means of the auto-correlation and cross-correlation bounds. The results derived from this study should be of interest to anyone performing matched filtering of ultrasonic signals with a moving emitter/receiver.

  15. Preliminary performance analysis of the advanced pulse compression noise radar waveform

    Science.gov (United States)

    Govoni, Mark A.; Moyer, Lee R.

    2012-06-01

    Noise radar systems encounter target fluctuation behavior similar to that of conventional systems. For noise radar systems, however, the fluctuations are not only dictated by target composition and geometry, but also by the non-uniform power envelope of their random transmit signals. This third dependency is of interest and serves as the basis for the preliminary analysis conducted in this manuscript. General conclusions are drawn on the implications of having a random power envelope and the impacts it could have on both the transmit and receive processes. Using an advanced pulse compression noise (APCN) radar waveform as the constituent signal, a computer simulation aids in quantifying potential losses and the impacts they might have on the detection performance of a real radar system.

  16. Type-I cascaded quadratic soliton compression in lithium niobate: Compressing femtosecond pulses from high-power fiber lasers

    DEFF Research Database (Denmark)

    Bache, Morten; Wise, Frank W.

    2010-01-01

    using second-harmonic generation in a type-I phase-matching configuration. We find that because of competing cubic material nonlinearities, compression can only occur in the nonstationary regime, where group-velocity-mismatch–induced Raman-like nonlocal effects prevent compression to less than 100 fs...

  17. Self compression and raman soliton generation in a photonic crystal fibre of 100-fs pulses produced by a diode-pumped Yb-doped oscillator

    DEFF Research Database (Denmark)

    Druon, F.; Sanner, N.; Lucas-Leclin, G.

    2003-01-01

    We present the use of a photonic crystal fiber to straightforwardly compress ultrashort pulses from a diode-pumped ytterbium laser emitting around 1 m. 75-fs pulse generation and a large 11.3-m tunability for sub-100-fs pulses is reported.......We present the use of a photonic crystal fiber to straightforwardly compress ultrashort pulses from a diode-pumped ytterbium laser emitting around 1 m. 75-fs pulse generation and a large 11.3-m tunability for sub-100-fs pulses is reported....

  18. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    Science.gov (United States)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-06-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  19. Multi-millijoule few-cycle mid-infrared pulses through nonlinear self-compression in bulk.

    Science.gov (United States)

    Shumakova, V; Malevich, P; Ališauskas, S; Voronin, A; Zheltikov, A M; Faccio, D; Kartashov, D; Baltuška, A; Pugžlys, A

    2016-09-13

    The physics of strong-field applications requires driver laser pulses that are both energetic and extremely short. Whereas optical amplifiers, laser and parametric, boost the energy, their gain bandwidth restricts the attainable pulse duration, requiring additional nonlinear spectral broadening to enable few or even single cycle compression and a corresponding peak power increase. Here we demonstrate, in the mid-infrared wavelength range that is important for scaling the ponderomotive energy in strong-field interactions, a simple energy-efficient and scalable soliton-like pulse compression in a mm-long yttrium aluminium garnet crystal with no additional dispersion management. Sub-three-cycle pulses with >0.44 TW peak power are compressed and extracted before the onset of modulation instability and multiple filamentation as a result of a favourable interplay between strong anomalous dispersion and optical nonlinearity around the wavelength of 3.9 μm. As a manifestation of the increased peak power, we show the evidence of mid-infrared pulse filamentation in atmospheric air.

  20. Multi-millijoule few-cycle mid-infrared pulses through nonlinear self-compression in bulk

    Science.gov (United States)

    Shumakova, V.; Malevich, P.; Ališauskas, S.; Voronin, A.; Zheltikov, A. M.; Faccio, D.; Kartashov, D.; Baltuška, A.; Pugžlys, A.

    2016-09-01

    The physics of strong-field applications requires driver laser pulses that are both energetic and extremely short. Whereas optical amplifiers, laser and parametric, boost the energy, their gain bandwidth restricts the attainable pulse duration, requiring additional nonlinear spectral broadening to enable few or even single cycle compression and a corresponding peak power increase. Here we demonstrate, in the mid-infrared wavelength range that is important for scaling the ponderomotive energy in strong-field interactions, a simple energy-efficient and scalable soliton-like pulse compression in a mm-long yttrium aluminium garnet crystal with no additional dispersion management. Sub-three-cycle pulses with >0.44 TW peak power are compressed and extracted before the onset of modulation instability and multiple filamentation as a result of a favourable interplay between strong anomalous dispersion and optical nonlinearity around the wavelength of 3.9 μm. As a manifestation of the increased peak power, we show the evidence of mid-infrared pulse filamentation in atmospheric air.

  1. Compression of 1030-nm femtosecond pulses after nonlinear spectral broadening in Corning® HI 1060 fiber: Theory and experiment

    Directory of Open Access Journals (Sweden)

    Michael E. Reilly

    2015-12-01

    Full Text Available We present the design and implementation of femtosecond pulse compression at 1030 nm based on spectral broadening in single-mode fiber, followed by dispersion compensation using an optimized double-pass SF11 prism pair. The source laser produced 1030-nm 144-fs pulses which were coupled into Corning® HI 1060 fiber, whose length was chosen to be 40 cm by using a pulse propagation model based on solving the generalized nonlinear Schrödinger equation. A maximum broadening to 60-nm bandwidth was obtained, following which compression to 60 ± 3 fs duration was achieved by using a prism-pair separation of 1025 ± 5 mm.

  2. Synthesis of picosecond pulses by spectral compression and shaping of femtosecond pulses in engineered quadratic nonlinear media.

    Science.gov (United States)

    Marangoni, M; Brida, D; Conforti, M; Capobianco, A D; Manzoni, C; Baronio, F; Nalesso, G F; De Angelis, C; Ramponi, R; Cerullo, G

    2009-02-01

    Narrow-bandwidth picosecond pulses of predetermined spectral and temporal shapes are generated with high efficiency by frequency conversion of femtosecond pulses in lithium tantalate crystals with engineered quasi-phase-matching structures. We give examples of the synthesis of Gaussian and super-Gaussian picosecond pulses and also of a pair of synchronized phase-coherent picosecond pulses with a predetermined carrier-frequency difference.

  3. Rate equation dynamics of passively mode-locked quasi-continuous lasers: pulse stability and dynamic pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    New, G.H.C.; Orkney, K.E.; Nock, M.J.W.

    1976-09-01

    New theoretical results connected with the stability of multiple pulsing in a passively mode-locked quasicontinuous laser in the rate equation approximation are presented. Together with earlier results, these allow the number of pulses per cavity transit to be predicted and a qualitative estimate made of the pulse duration for any combination of parameters. The results are illustrated by computer evolutions.

  4. Implementing and diagnosing magnetic flux compression on the Z pulsed power accelerator

    Energy Technology Data Exchange (ETDEWEB)

    McBride, Ryan D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bliss, David E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gomez, Matthew R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hansen, Stephanie B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Matthew R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jennings, Christopher Ashley [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Slutz, Stephen A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rovang, Dean C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knapp, Patrick F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schmit, Paul F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Awe, Thomas James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hess, M. H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lemke, Raymond W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dolan, D. H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lamppa, Derek C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jobe, Marc Ronald Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fang, Lu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hahn, Kelly D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chandler, Gordon A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cooper, Gary Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ruiz, Carlos L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Maurer, A. J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Robertson, Grafton Kincannon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cuneo, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sinars, Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tomlinson, Kurt [General Atomics, San Diego, CA (United States); Smith, Gary [General Atomics, San Diego, CA (United States); Paguio, Reny [General Atomics, San Diego, CA (United States); Intrator, Tom [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Weber, Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Greenly, John [Cornell Univ., Ithaca, NY (United States)

    2015-11-01

    We report on the progress made to date for a Laboratory Directed Research and Development (LDRD) project aimed at diagnosing magnetic flux compression on the Z pulsed-power accelerator (0-20 MA in 100 ns). Each experiment consisted of an initially solid Be or Al liner (cylindrical tube), which was imploded using the Z accelerator's drive current (0-20 MA in 100 ns). The imploding liner compresses a 10-T axial seed field, B z ( 0 ) , supplied by an independently driven Helmholtz coil pair. Assuming perfect flux conservation, the axial field amplification should be well described by B z ( t ) = B z ( 0 ) x [ R ( 0 ) / R ( t )] 2 , where R is the liner's inner surface radius. With perfect flux conservation, B z ( t ) and dB z / dt values exceeding 10 4 T and 10 12 T/s, respectively, are expected. These large values, the diminishing liner volume, and the harsh environment on Z, make it particularly challenging to measure these fields. We report on our latest efforts to do so using three primary techniques: (1) micro B-dot probes to measure the fringe fields associated with flux compression, (2) streaked visible Zeeman absorption spectroscopy, and (3) fiber-based Faraday rotation. We also mention two new techniques that make use of the neutron diagnostics suite on Z. These techniques were not developed under this LDRD, but they could influence how we prioritize our efforts to diagnose magnetic flux compression on Z in the future. The first technique is based on the yield ratio of secondary DT to primary DD reactions. The second technique makes use of the secondary DT neutron time-of-flight energy spectra. Both of these techniques have been used successfully to infer the degree of magnetization at stagnation in fully integrated Magnetized Liner Inertial Fusion (MagLIF) experiments on Z [P. F. Schmit et al. , Phys. Rev. Lett. 113 , 155004 (2014); P. F. Knapp et al. , Phys. Plasmas, 22 , 056312 (2015)]. Finally, we present some recent developments for designing

  5. Beam delivery and pulse compression to sub-50 fs of a modelocked thin-disk laser in a gas-filled Kagome-type HC-PCF fiber.

    Science.gov (United States)

    Emaury, Florian; Dutin, Coralie Fourcade; Saraceno, Clara J; Trant, Mathis; Heckl, Oliver H; Wang, Yang Y; Schriber, Cinia; Gerome, Frederic; Südmeyer, Thomas; Benabid, Fetah; Keller, Ursula

    2013-02-25

    We present two experiments confirming that hypocycloid Kagome-type hollow-core photonic crystal fibers (HC-PCFs) are excellent candidates for beam delivery of MW peak powers and pulse compression down to the sub-50 fs regime. We demonstrate temporal pulse compression of a 1030-nm Yb:YAG thin disk laser providing 860 fs, 1.9 µJ pulses at 3.9 MHz. Using a single-pass grating pulse compressor, we obtained a pulse duration of 48 fs (FWHM), a spectral bandwidth of 58 nm, and an average output power of 4.2 W with an overall power efficiency into the final polarized compressed pulse of 56%. The pulse energy was 1.1 µJ. This corresponds to a peak power of more than 10 MW and a compression factor of 18 taking into account the exact temporal pulse profile measured with a SHG FROG. The compressed pulses were close to the transform limit of 44 fs. Moreover, we present transmission of up to 97 µJ pulses at 10.5 ps through 10-cm long fiber, corresponding to more than twice the critical peak power for self-focusing in silica.

  6. Stirling-type pulse tube refrigerator (PTR) with cold compression: Cold compressor, colder expander

    Science.gov (United States)

    Park, Jiho; Ko, Junseok; Cha, Jeongmin; Jeong, Sangkwon

    2016-03-01

    This research paper focuses on the performance prediction and its validation via experimental investigation of a Stirling-type pulse tube refrigerator (PTR) equipped with a cold linear compressor. When the working gas is compressed at cryogenic temperature, the acoustic power (PV power) can be directly transmitted through the regenerator to the pulsating tube without experiencing unnecessary precooling process. The required PV power generated by the linear compressor, furthermore, can be significantly diminished due to the relatively small specific volume of the working gas at low temperature. The PTR can reach lower temperature efficiently with higher heat lift at the corresponding temperature than other typical single-stage Stirling-type PTRs. Utilizing a cryogenic reservoir as a warm end and regulating the entire operating temperature range of the PTR will enable a PTR to operate efficiently under space environment. In this research, the experimental validation as a proof of concept was carried out to demonstrate the capability of PTR operating between 80 K and 40 K. The linear compressor was submerged in a liquid nitrogen bath and the lowest temperature was measured as 38.5 K. The test results were analyzed to identify loss mechanisms with the simple numerical computation (linear model) which considers the dynamic characteristics of the cold linear compressor with thermo-hydraulic governing equations for each of sub components of the PTR. All the mass flows and pressure waves were assumed to be sinusoidal.

  7. Pulse Power Compression by Cutting a Dense Z-Pinch with a Laser Beam

    Science.gov (United States)

    Winterberg, F.

    1999-07-01

    A thin cut made through a z-pinch by an intense laser beam can become a magnetically insulated diode crossed by an intense ion beam. For larger cuts, the gap is crossed by an intense relativistic electron beam, stopped by magnetic bremsstrahlung resulting in a pointlike intense x-ray source. In either case, the impedance of the pinch discharge is increased, with the power delivered rising in the same pro-portion. A magnetically insulated cut is advantageous for three reasons: First, with the ion current com-parable to the Alfvèn ion current, the pinch instabilities are reduced. Second, with the energy deposit-ed into fast ions, a non-Maxwellian velocity distribution is established increasing value for nuclear fusion reactions taking place in the pinch discharge. Third, in a high density z-pinch plasma, the intense ion beam can launch a thermonuclear detonation wave propagating along the pinch discharge channel. For larger cuts the soft x-rays produced by magnetic bremsstrahlung can be used to drive a thermonuclear hohlraum target. Finally, the proposed pulse power compression scheme permits to use a cheap low power d.c. source charging a magnetic storage coil delivering the magnetically stored energy to the pinch discharge load by an exploding wire opening switch.

  8. Measurement of pulse amplitude and phase distortion in a semiconductor optical amplifier: from pulse compression to breakup

    DEFF Research Database (Denmark)

    Romstad, Francis Pascal; Borri, Paola; Langbein, Wolfgang Werner;

    2000-01-01

    We have performed extensive measurements of the propagation of ultrashort pulses in a semiconductor bulk amplifier using an ultrasensitive cross frequency-resolved optical gating technique. Pulses of 175-fs duration with energies from below 1 fJ to above 100 pJ are measured both in amplitude...... is biased for material transparency or absorption and to a pronounced pulse breakup in the gain regime....

  9. High Compact, High Quality Single Longitudinal Mode Hundred Picoseconds Laser Based on Stimulated Brillouin Scattering Pulse Compression

    Directory of Open Access Journals (Sweden)

    Zhenxu Bai

    2016-01-01

    Full Text Available A high beam quality hundred picoseconds single-longitudinal-mode (SLM laser is demonstrated based on stimulated Brillouin scattering (SBS pulse compression and aberration compensation. Flash-lamp-pumped Q-switched Nd3+:Y3Al5O12 (Nd:YAG SLM laser with Cr4+:Y3Al5O12 (Cr4+:YAG as a saturable absorber is used as the seed source. By combining master-oscillator-power-amplifier (MOPA, a compact single-cell with FC-770 as working medium is generated as pulse compressor. The 7.8 ns SLM laser is temporally compressed to about 450 ps, and 200 mJ energy is obtained at 1064 nm without optical damage. The energy stability is better than 3% with beam quality factor M2 less than 1.8, which makes this laser system an attractive source for scientific and industrial applications.

  10. Soliton compression to few-cycle pulses using quadratic nonlinear photonic crystal fibers: A design study

    DEFF Research Database (Denmark)

    Bache, Morten; Moses, Jeffrey; Lægsgaard, Jesper;

    2007-01-01

    We show theoretically that high-quality soliton compression from ~500 fs to ~10 fs is possible in poled silica photonic crystal fibers using cascaded (2):(2) nonlinearities. A moderate group-velocity mismatch optimizes the compression.......We show theoretically that high-quality soliton compression from ~500 fs to ~10 fs is possible in poled silica photonic crystal fibers using cascaded (2):(2) nonlinearities. A moderate group-velocity mismatch optimizes the compression....

  11. Design and fabrication of hollow-core photonic crystal fibers for high power fast laser beam transportation and pulse compression

    Science.gov (United States)

    Wang, Y. Y.; Peng, Xiang; Alharbi, M.; Dutin, C. F.; Bradley, T. D.; Mielke, Michael; Booth, Timothy; Benabid, F.

    2012-03-01

    We report on recent design and fabrication of Kagome type hollow-core photonic crystal fiber (HC-PCF) for the purpose of high power fast laser beam transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all Kagome fibers) of 40dB/km over a broadband transmission centered at 1500nm. We show that the large core size, low attenuation, broadband transmission, single modedness, low dispersion and relatively low banding loss makes it an ideal host for high power laser beam transportation. By filling the fiber with helium gas, a 74μJ, 850fs and 40kHz repetition rate ultra-short pulse at 1550nm has been faithfully delivered with little propagation pulse distortion. Compression of a 105μJ laser pulse from 850fs to 300fs has been achieved by operating the fiber in ambient air.

  12. Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

    Science.gov (United States)

    Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Ao, Tommy; Hickman, Randy; Wise, Jack; Wang, Zhongwu; Fan, Hongyou

    2017-01-01

    Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales. PMID:28300067

  13. Superfast assembly and synthesis of gold nanostructures using nanosecond low-temperature compression via magnetic pulsed power

    Science.gov (United States)

    Li, Binsong; Bian, Kaifu; Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Ao, Tommy; Hickman, Randy; Wise, Jack; Wang, Zhongwu; Fan, Hongyou

    2017-03-01

    Gold nanostructured materials exhibit important size- and shape-dependent properties that enable a wide variety of applications in photocatalysis, nanoelectronics and phototherapy. Here we show the use of superfast dynamic compression to synthesize extended gold nanostructures, such as nanorods, nanowires and nanosheets, with nanosecond coalescence times. Using a pulsed power generator, we ramp compress spherical gold nanoparticle arrays to pressures of tens of GPa, demonstrating pressure-driven assembly beyond the quasi-static regime of the diamond anvil cell. Our dynamic magnetic ramp compression approach produces smooth, shockless (that is, isentropic) one-dimensional loading with low-temperature states suitable for nanostructure synthesis. Transmission electron microscopy clearly establishes that various gold architectures are formed through compressive mesoscale coalescences of spherical gold nanoparticles, which is further confirmed by in-situ synchrotron X-ray studies and large-scale simulation. This nanofabrication approach applies magnetically driven uniaxial ramp compression to mimic established embossing and imprinting processes, but at ultra-short (nanosecond) timescales.

  14. Experimental approach and modelling of the mechanical behaviour of graphite fuel elements subjected to compression pulses

    Science.gov (United States)

    Forquin, P.

    2010-06-01

    Among the activities led by the Generation IV International Forum (GIF) relative to the future nuclear systems, the improvement of recycling of fuel elements and their components is a major issue. One of the studied systems by the GIF is the graphite-moderated high-temperature gas cooled reactor (HTGR). The fuel elements are composed of fuel roads half-inch in diameter named compacts. The compacts contain spherical particles made of actinide kernels about 500 m in diameter coated with three layers of carbon and silicon carbide, each about 50 m thick, dispersed in a graphite matrix. Recycling of compacts requires first a separation of triso-particles from the graphite matrix and secondly, the separation of the triso-coating from the kernels. This aim may be achieved by using pulsed currents: the compacts are placed within a cell filled by water and exposed to high voltage between 200 - 500 kV and discharge currents from 10 to 20 kA during short laps of time (about 2 µs) [1-2]. This repeated treatment leads to a progressive fragmentation of the graphite matrix and a disassembly of the compacts. In order to improve understanding of the fragmentation properties of compacts a series of quasi-static and dynamic experiments have been conducted with similar cylindrical samples containing 10% (volume fraction) of SiC particles coated in a graphite matrix. First, quasi-static compression tests have been performed to identify the mechanical behaviour of the material at low strain-rates (Fig.1). The experiments reveal a complex elasto-visco-plastic behaviour before a brittle failure. The mechanical response is characterised by a low yield stress (about 1 MPa), a strong strain-hardening in the loading phase and marked hysteresis-loops during unloading-reloading stages. Brittle failure is observed for axial stress about 13 MPa. In parallel, a series of flexural tests have been performed with the aim to characterise the quasi-static tensile strength of the particulate

  15. Experimental approach and modelling of the mechanical behaviour of graphite fuel elements subjected to compression pulses

    Directory of Open Access Journals (Sweden)

    Forquin P.

    2010-06-01

    Full Text Available Among the activities led by the Generation IV International Forum (GIF relative to the future nuclear systems, the improvement of recycling of fuel elements and their components is a major issue. One of the studied systems by the GIF is the graphite-moderated high-temperature gas cooled reactor (HTGR. The fuel elements are composed of fuel roads half-inch in diameter named compacts. The compacts contain spherical particles made of actinide kernels about 500 m in diameter coated with three layers of carbon and silicon carbide, each about 50 m thick, dispersed in a graphite matrix. Recycling of compacts requires first a separation of triso-particles from the graphite matrix and secondly, the separation of the triso-coating from the kernels. This aim may be achieved by using pulsed currents: the compacts are placed within a cell filled by water and exposed to high voltage between 200 – 500 kV and discharge currents from 10 to 20 kA during short laps of time (about 2 µs [1-2]. This repeated treatment leads to a progressive fragmentation of the graphite matrix and a disassembly of the compacts. In order to improve understanding of the fragmentation properties of compacts a series of quasi-static and dynamic experiments have been conducted with similar cylindrical samples containing 10% (volume fraction of SiC particles coated in a graphite matrix. First, quasi-static compression tests have been performed to identify the mechanical behaviour of the material at low strain-rates (Fig.1. The experiments reveal a complex elasto-visco-plastic behaviour before a brittle failure. The mechanical response is characterised by a low yield stress (about 1 MPa, a strong strain-hardening in the loading phase and marked hysteresis-loops during unloading-reloading stages. Brittle failure is observed for axial stress about 13 MPa. In parallel, a series of flexural tests have been performed with the aim to characterise the quasi-static tensile strength of the

  16. Nonlinear propagation analysis of few-optical-cycle pulses for subfemtosecond compression and carrier envelope phase effect

    Science.gov (United States)

    Mizuta, Yo; Nagasawa, Minoru; Ohtani, Morimasa; Yamashita, Mikio

    2005-12-01

    A numerical approach called Fourier direct method (FDM) is applied to nonlinear propagation of optical pulses with the central wavelength 800 nm, the width 2.67-12.00 fs, and the peak power 25-6870 kW in a fused-silica fiber. Bidirectional propagation, delayed Raman response, nonlinear dispersion (self-steepening, core dispersion), as well as correct linear dispersion are incorporated into “bidirectional propagation equations” which are derived directly from Maxwell’s equations. These equations are solved for forward and backward waves, instead of the electric-field envelope as in the nonlinear Schrödinger equation (NLSE). They are integrated as multidimensional simultaneous evolution equations evolved in space. We investigate, both theoretically and numerically, the validity and the limitation of assumptions and approximations used for deriving the NLSE. Also, the accuracy and the efficiency of the FDM are compared quantitatively with those of the finite-difference time-domain numerical approach. The time-domain size 500 fs and the number of grid points in time 2048 are chosen to investigate numerically intensity spectra, spectral phases, and temporal electric-field profiles up to the propagation distance 1.0 mm. On the intensity spectrum of a few-optical-cycle pulses, the self-steepening, core dispersion, and the delayed Raman response appear as dominant, middle, and slight effects, respectively. The delayed Raman response and the core dispersion reduce the effective nonlinearity. Correct linear dispersion is important since it affects the intensity spectrum sensitively. For the compression of femtosecond optical pulses by the complete phase compensation, the shortness and the pulse quality of compressed pulses are remarkably improved by the intense initial peak power rather than by the short initial pulse width or by the propagation distance longer than 0.1 mm. They will be compressed as short as 0.3 fs below the damage threshold of fused-silica fiber 6

  17. Efficient spectral broadening in the 100-W average power regime using gas-filled kagome HC-PCF and pulse compression.

    Science.gov (United States)

    Emaury, Florian; Saraceno, Clara J; Debord, Benoit; Ghosh, Debashri; Diebold, Andreas; Gèrôme, Frederic; Südmeyer, Thomas; Benabid, Fetah; Keller, Ursula

    2014-12-15

    We present nonlinear pulse compression of a high-power SESAM-modelocked thin-disk laser (TDL) using an Ar-filled hypocycloid-core kagome hollow-core photonic crystal fiber (HC-PCF). The output of the modelocked Yb:YAG TDL with 127 W average power, a pulse repetition rate of 7 MHz, and a pulse duration of 740 fs was spectrally broadened 16-fold while propagating in a kagome HC-PCF containing 13 bar of static argon gas. Subsequent compression tests performed using 8.4% of the full available power resulted in a pulse duration as short as 88 fs using the spectrally broadened output from the fiber. Compressing the full transmitted power through the fiber (118 W) could lead to a compressed output of >100  W of average power and >100  MW of peak power with an average power compression efficiency of 88%. This simple laser system with only one ultrafast laser oscillator and a simple single-pass fiber pulse compressor, generating both high peak power >100  MW and sub-100-fs pulses at megahertz repetition rate, is very interesting for many applications such as high harmonic generation and attosecond science with improved signal-to-noise performance.

  18. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  19. Experimental studies of high order soliton compression effect and gain characteristics in femtosecond laser pulses E3+r-doped fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Seed laser pulses with average power of 146 μW and pulse duration of 480 fs were amplified to 14.5 mW. The pulse duration was compressed to 260 fs using 6 m high concentration E3+r-doped fiber under forward pumping. The amplified signal pulse energy was 0.691 nJ (corresponding to a peak power of 2 657.7 W) and the repetition rate was 20.84 MHz. Spectrum breakup was observed simultaneously. The spectrum of pulses amplified by 3 m E3+r-doped fiber remains a single peak under different pump power. The amplified pulse duration was compressed abnormally with the increasing pump power using the backward pumping; that is, the amplified pulses were compressed with the increasing pump power under low pump power. When the pump power reached 38 mW, the shortest amplified pulse duration was 309 fs. With further increase in pump power, the amplified pulses began broadening, accompanied by a single peak spectrum under different pump power.

  20. Demonstration of an ultraviolet stimulated Brillouin scattering pulse compressed hundred picosecond laser in LiB3O5 crystals

    Science.gov (United States)

    Bai, Zhenxu; Wang, Yulei; Lu, Zhiwei; Jiang, Li; Yuan, Hang; Liu, Zhaohong

    2017-08-01

    A hundred picosecond ultraviolet (UV) laser is demonstrated with a pulse duration of less than 200 ps and peak power of 0.6 GW. With a hundred picosecond stimulated Brillouin scattering compressed pulse as the fundamental light, the UV output at 355 nm is obtained by extra-cavity sum-frequency-mixing in two LiB3O5 crystals. Maximum UV energy was 100 mJ when the incident energy was 280 mJ, yielding an optical-to-optical efficiency of 35.7%. This result is of interest for the generation of high energy sub-nanosecond UV lasers which finds applications in shock ignition and industrial processing.

  1. Self-compression in a solid fiber to 24 MW peak power with few-cycle pulses at 2 μm wavelength.

    Science.gov (United States)

    Gaida, C; Gebhardt, M; Stutzki, F; Jauregui, C; Limpert, J; Tünnermann, A

    2015-11-15

    We report on the experimental realization of a compact, fiber-based, ultrashort-pulse laser system in the 2 μm wavelength region delivering 24 fs pulse duration with 24 MW pulse peak power and 24.6 W average power. This performance level has been enabled by the favorable quadratic wavelength-dependence of the self-focusing limit, which has been experimentally verified to be at approximately 24 MW for circular polarization in a solid-core fused-silica fiber operated at a wavelength around 2 μm. The anomalous dispersion in this wavelength region allows for a simultaneous nonlinear spectral broadening and temporal pulse compression. This makes an additional compression stage redundant and facilitates a very simple and power-scalable approach. Simulations that include both the nonlinear pulse evolution and the transverse optical Kerr effect support the experimental results.

  2. Tonal Language Speech Compression Based on a Bitrate Scalable Multi-Pulse Based Code Excited Linear Prediction Coder

    Directory of Open Access Journals (Sweden)

    Suphattharachai Chomphan

    2011-01-01

    Full Text Available Problem statement: Speech compression is an important issue in the modern digital speech communication. The functionality of bitrates scalability also plays significant role, since the capacity of communication system varies all the time. When considering tonal speech, such as Thai, tone plays important role on the naturalness and the intelligibility of the speech, it must be treated appropriately. Therefore these issues are taken into account in this study. Approach: This study proposes a modification of flexible Multi-Pulse based Code Excited Linear Predictive (MP-CELP coder with bitrates scalabilities for tonal language speech in the multimedia applications. The coder consists of a core coder and bitrates scalable tools. The high pitch delay resolutions are applied to the adaptive codebook of core coder for tonal language speech quality improvement. The bitrates scalable tool employs multi-stage excitation coding based on an embedded-coding approach. The multi-pulse excitation codebook at each stage is adaptively produced depending on the selected excitation signal at the previous stage. Results: The experimental results show that the speech quality of the proposed coder is improved above the speech quality of the conventional coder without pitch-resolution adaptation. Conclusion: From the study, the proposed approach is able to improve the speech compression quality for tonal language and the functionality of bitrates scalability is also developed.

  3. Steady Secondary Flows Generated by Periodic Compression and Expansion of an Ideal Gas in a Pulse Tube

    Science.gov (United States)

    Lee, Jeffrey M.

    1999-01-01

    This study establishes a consistent set of differential equations for use in describing the steady secondary flows generated by periodic compression and expansion of an ideal gas in pulse tubes. Also considered is heat transfer between the gas and the tube wall of finite thickness. A small-amplitude series expansion solution in the inverse Strouhal number is proposed for the two-dimensional axisymmetric mass, momentum and energy equations. The anelastic approach applies when shock and acoustic energies are small compared with the energy needed to compress and expand the gas. An analytic solution to the ordered series is obtained in the strong temperature limit where the zeroth-order temperature is constant. The solution shows steady velocities increase linearly for small Valensi number and can be of order I for large Valensi number. A conversion of steady work flow to heat flow occurs whenever temperature, velocity or phase angle gradients are present. Steady enthalpy flow is reduced by heat transfer and is scaled by the Prandtl times Valensi numbers. Particle velocities from a smoke-wire experiment were compared with predictions for the basic and orifice pulse tube configurations. The theory accurately predicted the observed steady streaming.

  4. Application of wavelet filtering and Barker-coded pulse compression hybrid method to air-coupled ultrasonic testing

    Science.gov (United States)

    Zhou, Zhenggan; Ma, Baoquan; Jiang, Jingtao; Yu, Guang; Liu, Kui; Zhang, Dongmei; Liu, Weiping

    2014-10-01

    Air-coupled ultrasonic testing (ACUT) technique has been viewed as a viable solution in defect detection of advanced composites used in aerospace and aviation industries. However, the giant mismatch of acoustic impedance in air-solid interface makes the transmission efficiency of ultrasound low, and leads to poor signal-to-noise (SNR) ratio of received signal. The utilisation of signal-processing techniques in non-destructive testing is highly appreciated. This paper presents a wavelet filtering and phase-coded pulse compression hybrid method to improve the SNR and output power of received signal. The wavelet transform is utilised to filter insignificant components from noisy ultrasonic signal, and pulse compression process is used to improve the power of correlated signal based on cross-correction algorithm. For the purpose of reasonable parameter selection, different families of wavelets (Daubechies, Symlet and Coiflet) and decomposition level in discrete wavelet transform are analysed, different Barker codes (5-13 bits) are also analysed to acquire higher main-to-side lobe ratio. The performance of the hybrid method was verified in a honeycomb composite sample. Experimental results demonstrated that the proposed method is very efficient in improving the SNR and signal strength. The applicability of the proposed method seems to be a very promising tool to evaluate the integrity of high ultrasound attenuation composite materials using the ACUT.

  5. Direct measurement of magnetic flux compression on the Z pulsed-power accelerator

    Science.gov (United States)

    McBride, R. D.; Bliss, D. E.; Martin, M. R.; Jennings, C. A.; Lamppa, D. C.; Dolan, D. H.; Lemke, R. W.; Rovang, D. C.; Rochau, G. A.; Cuneo, M. E.; Sinars, D. B.; Intrator, T. P.; Weber, T. E.

    2016-10-01

    We report on the progress made to date for directly measuring magnetic flux compression on Z. Each experiment consisted of an initially solid aluminum liner (a cylindrical tube), which was imploded using Z's drive current (0-20 MA in 100 ns). The imploding liner compresses a 10-20-T axial seed field, Bz(0), supplied by an independently driven Helmholtz coil pair. Assuming perfect flux conservation, the axial field amplification should be well described by Bz(t) =Bz (0)×[R(0)/R(t)]2, where R is the liner's inner surface radius. With perfect flux conservation, Bz and dBz/dt values exceeding 104 T and 1012 T/s, respectively, are expected. These large values, the diminishing liner volume, and the harsh environment on Z, make it particularly challenging to measure these fields directly. We report on our latest efforts to do so using a fiber-optic-based Faraday rotation diagnostic, where the magneto-active portion of the sensor is made from terbium-doped optical fiber. We have now used this diagnostic to measure a flux-compressed magnetic field to over 600 T prior to the imploding liner hitting the on-axis fiber housing. This project was funded in part by Sandia's LDRD program and US DOE-NNSA contract DE-AC04-94AL85000.

  6. High-Average-Power Diffraction Pulse-Compression Gratings Enabling Next-Generation Ultrafast Laser Systems

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-11-01

    Pulse compressors for ultrafast lasers have been identified as a technology gap in the push towards high peak power systems with high average powers for industrial and scientific applications. Gratings for ultrashort (sub-150fs) pulse compressors are metallic and can absorb a significant percentage of laser energy resulting in up to 40% loss as well as thermal issues which degrade on-target performance. We have developed a next generation gold grating technology which we have scaled to the petawatt-size. This resulted in improvements in efficiency, uniformity and processing as compared to previous substrate etched gratings for high average power. This new design has a deposited dielectric material for the grating ridge rather than etching directly into the glass substrate. It has been observed that average powers as low as 1W in a compressor can cause distortions in the on-target beam. We have developed and tested a method of actively cooling diffraction gratings which, in the case of gold gratings, can support a petawatt peak power laser with up to 600W average power. We demonstrated thermo-mechanical modeling of a grating in its use environment and benchmarked with experimental measurement. Multilayer dielectric (MLD) gratings are not yet used for these high peak power, ultrashort pulse durations due to their design challenges. We have designed and fabricated broad bandwidth, low dispersion MLD gratings suitable for delivering 30 fs pulses at high average power. This new grating design requires the use of a novel Out Of Plane (OOP) compressor, which we have modeled, designed, built and tested. This prototype compressor yielded a transmission of 90% for a pulse with 45 nm bandwidth, and free of spatial and angular chirp. In order to evaluate gratings and compressors built in this project we have commissioned a joule-class ultrafast Ti:Sapphire laser system. Combining the grating cooling and MLD technologies developed here could enable petawatt laser systems to

  7. Irregular Segmented Region Compression Coding Based on Pulse Coupled Neural Network

    Institute of Scientific and Technical Information of China (English)

    MA Yi-de; QI Chun-liang; QIAN Zhi-bai; SHI Fei; ZHANG Bei-dou

    2006-01-01

    An irregular segmented region coding algorithm based on pulse coupled neural network(PCNN) is presented. PCNN has the property of pulse-coupled and changeable threshold, through which these adjacent pixels with approximate gray values can be activated simultaneously. One can draw a conclusion that PCNN has the advantage of realizing the regional segmentation, and the details of original image can be achieved by the parameter adjustment of segmented images, and at the same time, the trivial segmented regions can be avoided. For the better approximation of irregular segmented regions, the Gram-Schmidt method, by which a group of orthonormal basis functions is constructed from a group of linear independent initial base functions, is adopted. Because of the orthonormal reconstructing method, the quality of reconstructed image can be greatly improved and the progressive image transmission will also be possible.

  8. Active cooling of pulse compression diffraction gratings for high energy, high average power ultrafast lasers.

    Science.gov (United States)

    Alessi, David A; Rosso, Paul A; Nguyen, Hoang T; Aasen, Michael D; Britten, Jerald A; Haefner, Constantin

    2016-12-26

    Laser energy absorption and subsequent heat removal from diffraction gratings in chirped pulse compressors poses a significant challenge in high repetition rate, high peak power laser development. In order to understand the average power limitations, we have modeled the time-resolved thermo-mechanical properties of current and advanced diffraction gratings. We have also developed and demonstrated a technique of actively cooling Petawatt scale, gold compressor gratings to operate at 600W of average power - a 15x increase over the highest average power petawatt laser currently in operation. Combining this technique with low absorption multilayer dielectric gratings developed in our group would enable pulse compressors for petawatt peak power lasers operating at average powers well above 40kW.

  9. The drive beam pulse compression system for the CLIC RF power source

    CERN Document Server

    Corsini, R

    1999-01-01

    The Compact LInear Collider (CLIC) is a high energy (0.5 to 5 TeV) e ± linear collider that uses a high- current electron beam (the drive beam) for 30 GHz RF power production by the Two-Beam Acceleration (TBA) method. Recently, a new cost­effective and efficient generation scheme for the drive beam has been developed. A fully­loaded normal­conducting linac operating at lower frequency (937 MHz) generates and accelerates the drive beam bunches, and a compression system composed of a delay­line and two combiner rings produces the proper drive beam time structure for RF power generation in the drive beam decelerator. In this paper, a preliminary design of the whole compression system is presented. In particular, the fundamental issue of preserving the bunch quality along the complex is studied and its impact on the beam parameters and on the various system components is assessed. A first design of the rings and delay­line lattice, including path length tuning chicanes, injection and extraction regions is a...

  10. Magnetic flux compression experiments on the Z pulsed-power accelerator

    Science.gov (United States)

    McBride, R. D.; Gomez, M. R.; Hansen, S. B.; Jennings, C. A.; Bliss, D. E.; Knapp, P. F.; Schmit, P. F.; Awe, T. J.; Martin, M. R.; Sinars, D. B.; Greenly, J. B.; Intrator, T. P.; Weber, T. E.

    2014-10-01

    We report on the progress made to date for diagnosing magnetic flux compression on Z. Each experiment consisted of an initially solid Be or Al liner (cylindrical tube), which was imploded using Z's drive current (0-20 MA in 100 ns). The imploding liner compresses a 10-T axial seed field, Bz(0), supplied by an independently driven Helmholtz coil pair. Assuming perfect flux conservation, the axial field amplification should be well described by Bz (t) =Bz (0) × [ R (0) / R (t) ]2 , where R is the liner's inner surface radius. With perfect flux conservation, Bz and dBz/dt values exceeding 104 T and 1012 T/s, respectively, are expected. These large values, the diminishing liner volume, and the harsh environment on Z, make it particularly challenging to measure these fields. We report our latest efforts to do so using three primary techniques: (1) micro B-dot probes, (2) streaked visible Zeeman spectroscopy, and (3) fiber-based Faraday rotation. We will also briefly highlight some recent developments using neutron diagnostics (ratio of secondary DT to primary DD neutrons and secondary DT neutron energy spectra) to assess the degree of magnetization in fully integrated magnetized liner inertial fusion (MagLIF) experiments on Z. This project was funded in part by Sandia's LDRD program and US DOE-NNSA Contract DE-AC04-94AL85000.

  11. Multi-meter fiber-delivery and pulse self-compression of milli-Joule femtosecond laser and fiber-aided laser-micromachining.

    Science.gov (United States)

    Debord, B; Alharbi, M; Vincetti, L; Husakou, A; Fourcade-Dutin, C; Hoenninger, C; Mottay, E; Gérôme, F; Benabid, F

    2014-05-01

    We report on damage-free fiber-guidance of milli-Joule energy-level and 600-femtosecond laser pulses into hypocycloid core-contour Kagome hollow-core photonic crystal fibers. Up to 10 meter-long fibers were used to successfully deliver Yb-laser pulses in robustly single-mode fashion. Different pulse propagation regimes were demonstrated by simply changing the fiber dispersion and gas. Self-compression to ~50 fs, and intensity-level nearing petawatt/cm(2) were achieved. Finally, free focusing-optics laser-micromachining was also demonstrated on different materials.

  12. Speckle Reduction for Ultrasonic Imaging Using Frequency Compounding and Despeckling Filters along with Coded Excitation and Pulse Compression

    Directory of Open Access Journals (Sweden)

    Joshua S. Ullom

    2012-01-01

    Full Text Available A method for improving the contrast-to-noise ratio (CNR while maintaining the −6 dB axial resolution of ultrasonic B-mode images is proposed. The technique proposed is known as eREC-FC, which enhances a recently developed REC-FC technique. REC-FC is a combination of the coded excitation technique known as resolution enhancement compression (REC and the speckle-reduction technique frequency compounding (FC. In REC-FC, image CNR is improved but at the expense of a reduction in axial resolution. However, by compounding various REC-FC images made from various subband widths, the tradeoff between axial resolution and CNR enhancement can be extended. Further improvements in CNR can be obtained by applying postprocessing despeckling filters to the eREC-FC B-mode images. The despeckling filters evaluated were the following: median, Lee, homogeneous mask area, geometric, and speckle-reducing anisotropic diffusion (SRAD. Simulations and experimental measurements were conducted with a single-element transducer (f/2.66 having a center frequency of 2.25 MHz and a −3 dB bandwidth of 50%. In simulations and experiments, the eREC-FC technique resulted in the same axial resolution that would be typically observed with conventional excitation with a pulse. Moreover, increases in CNR of 348% were obtained in experiments when comparing eREC-FC with a Lee filter to conventional pulsing methods.

  13. RF Pulse compression stabilization at the CTF3 CLIC test facility

    CERN Document Server

    Dubrovskiy, Alexey

    2010-01-01

    In the CTF3 accelerator, the RF produced by each of ten 3 GHz klystrons goes through waveguides, RF pulse compressors and splitters. The RF phase and power transformation of these devices depend on their temperature. The quantitative effect of the room temperature variation on the RF was measured. It is the major source of undesired changes during the CTF3 operation. An RF phaseloop and a compressor temperature stabilization are developed to suppress the phase fluctuation and the power profile change due to the temperature variation. The implementation is transparent for operators, it does not limit anyhow the flexibility of RF manipulations. Expected and measured suppression characteristics will be given.

  14. Pulse

    Science.gov (United States)

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the person's heart is pumping. Pulse ... rate gives information about your fitness level and health.

  15. Air-guided photonic-crystal-fiber pulse-compression delivery of multimegawatt femtosecond laser output for nonlinear-optical imaging and neurosurgery

    Science.gov (United States)

    Lanin, Aleksandr A.; Fedotov, Il'ya V.; Sidorov-Biryukov, Dmitrii A.; Doronina-Amitonova, Lyubov V.; Ivashkina, Olga I.; Zots, Marina A.; Sun, Chi-Kuang; Ömer Ilday, F.; Fedotov, Andrei B.; Anokhin, Konstantin V.; Zheltikov, Aleksei M.

    2012-03-01

    Large-core hollow photonic-crystal fibers (PCFs) are shown to enable a fiber-format air-guided delivery of ultrashort infrared laser pulses for neurosurgery and nonlinear-optical imaging. With an appropriate dispersion precompensation, an anomalously dispersive 15-μm-core hollow PCF compresses 510-fs, 1070-nm light pulses to a pulse width of about 110 fs, providing a peak power in excess of 5 MW. The compressed PCF output is employed to induce a local photodisruption of corpus callosum tissues in mouse brain and is used to generate the third harmonic in brain tissues, which is captured by the PCF and delivered to a detector through the PCF cladding.

  16. Kagome-type hollow-core photonic crystal fibers for beam delivery and pulse compression of high-power ultrafast lasers

    Science.gov (United States)

    Saraceno, C. J.; Emaury, F.; Diebold, A.; Schriber, C.; Debord, B.; Gérôme, F.; Südmeyer, T.; Benabid, F.; Keller, U.

    2015-02-01

    Tremendous progress has been achieved in the last years in the field of ultrafast high-power sources. Among the different laser technologies driving this progress, thin-disk lasers (TDLs) have gained significant ground, both from amplifiers and modelocked oscillators. Modelocked TDLs are particularly attractive, as they allow for unprecedented high energy and average powers directly from an oscillator. The exponential progress in the performance of these sources drives growing needs for efficient means of beam delivery and pulse compression at high average power ( 10 MW). This remains a challenging regime for standard fiber solutions: microstructured large-mode-area silica photonic-crystal fibers (PCFs) are good candidates, but peak powers are limited to ≈4-6 MW by self-focusing. Hollow-core (HC) capillaries are adapted for higher peak powers, but exhibit high losses and are not suitable for compact beam delivery. In parallel to the progress achieved in the performance of ultrafast laser systems, recent progress in novel hollow-core PCF designs are currently emerging as an excellent solution for these challenges. In particular, Inhibited-coupling Kagome-type HC-PCFs are particularly promising: their intrinsic guiding properties allow for extremely high damage thresholds, low losses over wide transmission windows and ultra-low dispersion. In our most recent results, we achieve pulse compression in the hundred-watt average power regime using Kagome-type HC-PCFs. We launch 127-W, 18-μJ, 740-fs pulses from our modelocked TDL into an Ar-filled fiber (13 bar), reaching 93% transmission. The resulting spectral broadening allows us to compress the pulses to 88 fs at 112 W of average power, reaching 105 MW of peak power, at 88% compression efficiency. These results demonstrate the outstanding suitability of Kagome HC-PCFs for compression and beam delivery of state-of-the-art kilowatt-class ultrafast systems.

  17. Compression and radiation of high-power short rf pulses. II. A novel antenna array design with combined compressor/radiator elements

    KAUST Repository

    Sirenko, Kostyantyn

    2011-01-01

    The paper discusses the radiation of compressed high power short RF pulses using two different types of antennas: (i) A simple monopole antenna and (ii) a novel array design, where each of the elements is constructed by combining a compressor and a radiator. The studies on the monopole antenna demonstrate the possibility of a high power short RF pulse\\'s efficient radiation even using simple antennas. The studies on the novel array design demonstrate that a reduced size array with lower pulse distortion and power decay can be constructed by assembling the array from elements each of which integrates a compressor and a radiator. This design idea can be used with any type of antenna array; in this work it is applied to a phased array.

  18. 50-GHz repetition-rate, 280-fs pulse generation at 100-mW average power from a mode-locked laser diode externally compressed in a pedestal-free pulse compressor

    Science.gov (United States)

    Tamura, Kohichi R.; Sato, Kenji

    2002-07-01

    280-fs pedestal-free pulses are generated at average output powers exceeding 100 mW at a repetition rate of 50 GHz by compression of the output of a mode-locked laser diode (MLLD) by use of a pedestal-free pulse compressor (PFPC). The MLLD consists of a monolithically integrated chirped distributed Bragg reflector, a gain section, and an electroabsorption modulator. The PFPC is composed of a dispersion-flattened dispersion-decreasing fiber and a dispersion-flattened dispersion-imbalanced nonlinear optical loop mirror. Frequency modulation for linewidth broadening is used to overcome the power limitation imposed by stimulated Brillouin scattering.

  19. Self-focusing and self-compression of a laser pulse in the presence of an external tapered magnetized density-ramp plasma

    Science.gov (United States)

    Saedjalil, N.; Jafari, S.

    2016-06-01

    In this paper, the effects of external tapered axial magnetic field and plasma density-ramp on the spatiotemporal evolution of the laser pulse in inhomogeneous plasma have been studied. The external magnetic field can modify the refractive index of plasma and consequently intensifies the nonlinear effects. By considering the relativistic nonlinearity effect, self-focusing and self-compression of the laser beam propagating through the magnetized plasma have been investigated, numerically. Numerical results indicate that self-focusing and self-compression are better enhanced in a tapered magnetic field than in a uniform one. Besides, in plasma density-ramp profile, self-focusing and self-compression of the laser beam improve in comparison with no ramp structure. In addition, with increasing both the slope of the density ramp and slope constant parameter of the tapered magnetic field, the laser focusing increases, properly, in short distances of the laser propagation through the plasma.

  20. MATHEON Workshop 2013

    CERN Document Server

    Calderbank, Robert; Kutyniok, Gitta; Vybíral, Jan

    2015-01-01

    Since publication of the initial papers in 2006, compressed sensing has captured the imagination of the international signal processing community, and the mathematical foundations are nowadays quite well understood. Parallel to the progress in mathematics, the potential applications of compressed sensing have been explored by many international groups of, in particular, engineers and applied mathematicians, achieving very promising advances in various areas such as communication theory, imaging sciences, optics, radar technology, sensor networks, or tomography. Since many applications have reached a mature state, the research center MATHEON in Berlin focusing on "Mathematics for Key Technologies", invited leading researchers on applications of compressed sensing from mathematics, computer science, and engineering to the "MATHEON Workshop 2013: Compressed Sensing and its Applications” in December 2013. It was the first workshop specifically focusing on the applications of compressed sensing. This book featur...

  1. High-power, mid-infrared, picosecond pulses generated by compression of a CO2 laser beat-wave in GaAs

    CERN Document Server

    Pigeon, J J; Joshi, C

    2015-01-01

    We report on the generation of a train of ~ 2 ps, 10 um laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO2 laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  2. High-power, mid-infrared, picosecond pulses generated by compression of a CO₂ laser beat-wave in GaAs.

    Science.gov (United States)

    Pigeon, J J; Tochitsky, S Ya; Joshi, C

    2015-12-15

    We report on the generation of a train of ∼2  ps, 10 μm laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl crystals. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO₂ laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves, we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  3. High-power, mid-infrared, picosecond pulses generated by compression of a CO_2 laser beat-wave in GaAs

    Science.gov (United States)

    Pigeon, J. J.; Tochitsky, S. Ya.; Joshi, C.

    2015-12-01

    We report on the generation of a train of ~ 2 ps, 10 um laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO2 laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  4. Spatial Pulse Compression.

    Science.gov (United States)

    1980-03-01

    50epotr100t) i Toi deerinefndune the proper wavfomortanmting anrtenorws Fudiven0with a9 2E nOD(anosec o imuer&ieiesr and hensutibylkng avefrm hc a hr )~~ BdD ...zero- Phase at Fitted Points one polarity ) crossings) Number of Fitted Points --- 22. 48. Number of Individual Time-Measurements --- --- 22. 122...clear reversal of polarity , cutting definitively through zero voltage. In other words, from a practical waveform standpoint, N = 1 will actually be the

  5. Elastic wave velocity inspection for rocks by pulse compression method%脉冲压缩方法检测岩石弹性波速度

    Institute of Scientific and Technical Information of China (English)

    李长征; 张碧星; 师芳芳

    2013-01-01

    On account of existing problems in rock elastic wave velocity inspecting,such as low signal to noise ratio(SNR),difficulty in reading the prime time of echo and inspecting large volume rock,pulse compression method is proposed.Linear frequency modulation (LFM) signal is mostly used as exciting source due to its remarkable properties,such as wide bandwidth,high energy and high SNR.While receiving terminal,echo signal is filtered by a matched filter,and the compression signal of high SNR is obtained.The wide time and band characteristics of LFM signal are introduced.In addition,the pulse compression principle and digital implementation process are also analyzed.The influence of the bandwidth of transducer on exciting signal is studied; elastic wave velocity of several rocks is inspected with a conventional method and pulse compression method.The wave velocity differences of two testing methods show a limited error.The detailed implementation and calculating process of pulse compression inspecting method are also described.The advantages and prospects of the method are analyzed.Results show that pulse compression method can be applied to inspect the elastic wave velocity in rock and access engineering quality.%针对岩石弹性波速度检测信噪比低、回波信号初至时间不易判读,以及较长岩石(或混凝土)超声检测难以穿透问题,提出用脉冲压缩方法检测弹性波速度.该方法与超声脉冲法检测的不同之处是在发射端采用编码信号激励,在接收端进行匹配滤波,得到高信噪比的压缩信号.介绍线性调频信号的宽时宽带特性,分析了脉冲压缩的基本原理和数字实现过程.试验研究了换能器带宽对激发信号的影响.用常规的单脉冲法和脉冲压缩方法检测了多个岩样的弹性波速度,试验结果表明,两种检测结果差异较小.给出了脉冲压缩方法用于岩石弹性波速度检测的具体步骤和计算过程.综合分析,脉冲压缩方法检

  6. STRAIN LOCALIZATION PECULIARITIES AND DISTRIBUTION OF ACOUSTIC EMISSION SOURCES IN ROCK SAMPLES TESTED BY UNIAXIAL COMPRESSION AND EXPOSED TO ELECTRIC PULSES

    Directory of Open Access Journals (Sweden)

    V. A. Mubassarova

    2015-09-01

    Full Text Available Results of uniaxial compression tests of rock samples in electromagnetic fields are presented. The experiments were performed in the Laboratory of Basic Physics of Strength, Institute of Continuous Media Mechanics, Ural Branch of RAS (ICMM. Deformation of samples was studied, and acoustic emission (AE signals were recorded. During the tests, loads varied by stages. Specimens of granite from the Kainda deposit in Kyrgyzstan (similar to samples tested at the Research Station of RAS, hereafter RS RAS were subject to electric pulses at specified levels of compression load. The electric pulses supply was galvanic; two graphite electrodes were fixed at opposite sides of each specimen. The multichannel Amsy-5 Vallen System was used to record AE signals in the six-channel mode, which provided for determination of spatial locations of AE sources. Strain of the specimens was studied with application of original methods of strain computation based on analyses of optical images of deformed specimen surfaces in LaVISION Strain Master System.Acoustic emission experiment data were interpreted on the basis of analyses of the AE activity in time, i.e. the number of AE events per second, and analyses of signals’ energy and AE sources’ locations, i.e. defects.The experiment was conducted at ICMM with the use of the set of equipment with advanced diagnostic capabilities (as compared to earlier experiments described in [Zakupin et al., 2006a, 2006b; Bogomolov et al., 2004]. It can provide new information on properties of acoustic emission and deformation responses of loaded rock specimens to external electric pulses.The research task also included verification of reproducibility of the effect (AE activity when fracturing rates responded to electrical pulses, which was revealed earlier in studies conducted at RS RAS. In terms of the principle of randomization, such verification is methodologically significant as new effects, i.e. physical laws, can be considered

  7. High-power Microwave Pulse Compression of Klystrons by Phase-Modulation of High-Q Storage Cavities

    CERN Document Server

    Bossart, Rudolf; Mourier, J; Syratchev, I V; Tanner, L

    2004-01-01

    At the CERN linear electron accelerators LIL and CTF, the peak RF power from the 3GHz-klystrons was doubled by means of LIPS microwave pulse compressors. To produce constant RF power from the cavity-based pulse compressors, the klystrons were driven by a fast RF-phase modulation program. For the CLIC Test Facility CTF3, a new type of a Barrel Open Cavity (BOC) with a high quality factor Q0 has been developed. Contrary to LIPS with two resonant cavities, BOC operates with a single cavity supporting two orthogonal resonant modes TM 10,1,1 in the same cavity. For both LIPS and BOC storage cavities, it is important that the RF power reflected back to the klystron is minimal. This implies that the resonant frequencies, Q-factors and coupling factors of the two resonant modes of a pulse compressor are closely matched, and that the resonant frequencies are accurate to within a few KHz. The effects of small differences between the two orthogonal modes of the BOC cavity have been investigated. The dynamic pulse respon...

  8. Some background information for the workshop

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, J. M.

    1997-09-01

    By way of an introduction to the Workshop on Cold Moderators for Pulsed Neutron Sources, this paper surveys the highlights of early cold source developments, summarizes the world situation in existing pulsed neutron sources and advanced pulsed neutron source projects, and explores some of the general features and performance of cold moderators for pulsed neutron sources. (auth)

  9. Millimeter-wave circuits and pulse compression radar baseband/analog signal processing blocks in silicon processes

    OpenAIRE

    2012-01-01

    The power dissipation and cost of the next generation pulse radar beamforming systems needs to be reduced for the imaging and surveillance sensors. This research work aims at developing and innovating the next generation, mobile hand-held, high performance radar systems for outdoor surveillance applications, i.e. pedestrian detection sensor. Integrating the low cost millimeter-wave (mm-wave) imaging array platforms with advanced analog/ baseband signal processing on silicon is proposed for re...

  10. Ultrasonic position and velocity measurement for a moving object by M-sequence pulse compression using Doppler velocity estimation by spectrum-pattern analysis

    Science.gov (United States)

    Ikari, Yohei; Hirata, Shinnosuke; Hachiya, Hiroyuki

    2015-07-01

    Pulse compression using a maximum-length sequence (M-sequence) can improve the signal-to-noise ratio (SNR) of the reflected echo in the pulse-echo method. In the case of a moving object, however, the echo is modulated owing to the Doppler effect. The Doppler-shifted M-sequence-modulated signal cannot be correlated with the reference signal that corresponds to the transmitted M-sequence-modulated signal. Therefore, Doppler velocity estimation by spectrum-pattern analysis of a cyclic M-sequence-modulated signal and cross correlations with Doppler-shifted reference signals that correspond to the estimated Doppler velocities has been proposed. In this paper, measurements of the position and velocity of a moving object by the proposed method are described. First, Doppler velocities of the object are estimated using a microphone array. Secondly, the received signal from each microphone is correlated with each Doppler-shifted reference signal. Then, the position of the object is determined from the B-mode image formed from all cross-correlation functions. After that, the velocity of the object is calculated from velocity components estimated from the Doppler velocities and the position. Finally, the estimated Doppler velocities, determined positions, and calculated velocities are evaluated.

  11. Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

    Science.gov (United States)

    d'Almeida, T.; Lassalle, F.; Morell, A.; Grunenwald, J.; Zucchini, F.; Loyen, A.; Maysonnave, T.; Chuvatin, A. S.

    2013-09-01

    SPHINX is a 6 MA, 1-μs Linear Transformer Driver (LTD) operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being evaluated to improve the generator performances are an upgrade to a 20 MA, 1-μs LTD machine and various power amplification schemes, including a compact Dynamic Load Current Multiplier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse in order to obtain the desired load current profile. In this paper, we discuss the overall configuration that was selected for these experiments, including the choice of a coaxial cylindrical geometry for the load and its return current electrode. We present both 3-D Magneto-hydrodynamic and 1D Lagrangian hydrodynamic simulations which helped guide the design of the experimental configuration. Initial results obtained over a set of experiments on an aluminium cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented and analyzed. Details of the electrical and laser Doppler interferometer setups used to monitor and diagnose the ramp compression experiments are provided. In particular, the configuration used to field both homodyne and heterodyne velocimetry diagnostics in the reduced access available within the liner's interior is described. Current profiles measured at various critical locations across the system, particularly the load current, enabled a comprehensive tracking of the current circulation and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements obtained from the heterodyne velocimeter agree with the hydrocode results obtained using the measured load current as the input. An extensive hydrodynamic analysis is carried out to examine information such as pressure and particle velocity history profiles or magnetic

  12. Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

    Energy Technology Data Exchange (ETDEWEB)

    D' Almeida, T.; Lassalle, F.; Morell, A.; Grunenwald, J.; Zucchini, F.; Loyen, A. [CEA, DAM, GRAMAT, F-46500 Gramat (France); Maysonnave, T. [International Technologies for High Pulsed Power, F-46500 Thégra (France); Chuvatin, A. S. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-09-15

    SPHINX is a 6 MA, 1-μs Linear Transformer Driver (LTD) operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being evaluated to improve the generator performances are an upgrade to a 20 MA, 1-μs LTD machine and various power amplification schemes, including a compact Dynamic Load Current Multiplier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse in order to obtain the desired load current profile. In this paper, we discuss the overall configuration that was selected for these experiments, including the choice of a coaxial cylindrical geometry for the load and its return current electrode. We present both 3-D Magneto-hydrodynamic and 1D Lagrangian hydrodynamic simulations which helped guide the design of the experimental configuration. Initial results obtained over a set of experiments on an aluminium cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented and analyzed. Details of the electrical and laser Doppler interferometer setups used to monitor and diagnose the ramp compression experiments are provided. In particular, the configuration used to field both homodyne and heterodyne velocimetry diagnostics in the reduced access available within the liner's interior is described. Current profiles measured at various critical locations across the system, particularly the load current, enabled a comprehensive tracking of the current circulation and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements obtained from the heterodyne velocimeter agree with the hydrocode results obtained using the measured load current as the input. An extensive hydrodynamic analysis is carried out to examine information such as pressure and particle velocity history profiles or

  13. Design of LFM Pulse Compression Based on FPGA IP Core%线性调频信号基于FPGA IP核的脉冲压缩设计

    Institute of Scientific and Technical Information of China (English)

    张旭; 李巍

    2011-01-01

    A hardware platform based on the field programmable gate array ( FPGA) was designed to implement the digital puLse compression of LFM (Line Frequency Modulation) signal. The design method of pulse compression based on FPGA IP core is proposed in this thesis. The theoretical analysis and MATLAB simulation are performed for pulse compression. With the accomplishment of designs, a comprehensive evaluation test on system software and hardware was conducted, as well as analysis on result of pulse compression based real-time experimental data. The result shows that the system is capable to perform 1 024-points pulse compression. The indexes of the amplitude ratio of main lobe to side lobe and mail lobe width are consistent with the result of theoretical simulation. The design method can conduct parameter setting flexibly, simplify software design and shorten the period of research and development.%为实现线性调频信号的数字脉冲压缩,设计一个FPGA硬件平台,并着重提出一种基于FPGA IP核的脉冲压缩设计方法.针对脉冲压缩进行了理论分析和Matlab仿真,设计完成后对系统软、硬件进行了全面测试,并根据实测数据对脉冲压缩结果进行了分析.结果表明,该系统可实现1 024点的脉冲压缩功能,主副瓣比、主瓣宽度等指标与理论仿真结果一致.该方法的参数设置灵活,可以简化软件设计,缩短研发周期.

  14. Monolithic all-PM femtosecond Yb-fiber laser stabilized with a narrow-band fiber Bragg grating and pulse-compressed in a hollow-core photonic crystal fiber

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2008-01-01

    We report on an environmentally stable self-starting monolithic (i.e. without any free-space coupling) all-polarization-maintaining (PM) femtosecond Yb-fiber laser, stabilized against Q-switching by a narrow-band fiber Bragg grating and modelocked using a semiconductor saturable absorber mirror....... The laser output is compressed in a spliced-on hollow-core PM photonic crystal fiber, thus providing direct end-of-the-fiber delivery of pulses of around 370 fs duration and 4 nJ energy with high mode quality. Tuning the pump power of the end amplifier of the laser allows for the control of output pulse...

  15. Pulse Compression Realization of Radar Linear Frequency Modulation Signal Via CUDA%基于CUDA的雷达线性调频信号脉冲压缩实现

    Institute of Scientific and Technical Information of China (English)

    江艳阳; 黄双华; 刘峰; 白海东

    2011-01-01

    This paper uses the GPU as the platform of radar simulation and introduces the CUDA technology to realize the algorithm of pulse compression of radar linear frequency modulation signal,and compares the CPU algorithm.The simulation result indicates that the algorithm of CUDA gets a higher operation rate than the CPU on the pulse compression.%利用图形处理器(GPU)作为雷达仿真平台,采用统一计算设备架构(CUDA)技术,实现雷达线性调频信号脉冲压缩算法,并与CPU算法进行比较。实验结果表明利用CUDA技术实现的脉冲压缩算法取得了比CPU算法明显较高的运算效率。

  16. INDICO Workshop

    CERN Document Server

    CERN. Geneva; Fabbrichesi, Marco

    2004-01-01

    The INtegrated DIgital COnferencing EU project has finished building a complete software solution to facilitate the MANAGEMENT OF CONFERENCES, workshops, schools or simple meetings from their announcement to their archival. Everybody involved in the organization of events is welcome to join this workshop, in order to understand the scope of the project and to see demonstrations of the various features.

  17. Contributions To The 9th Workshop On Rf Superconductivity, Accelerator Technology For The 21st Century (rf Superconductivity Activities At Lal Accelerating Field Measurement In 3 Ghz Pulsed Cavities Design And Test Of A 1.3 Ghz Travelling Wave Window

    CERN Document Server

    Le Duff, J; Thomas, C

    2000-01-01

    Contributions To The 9th Workshop On Rf Superconductivity, Accelerator Technology For The 21st Century (rf Superconductivity Activities At Lal Accelerating Field Measurement In 3 Ghz Pulsed Cavities Design And Test Of A 1.3 Ghz Travelling Wave Window

  18. Exawatt-Zettawatt Pulse Generation and Applications

    OpenAIRE

    Mourou, G. A.; Fisch, N. J.; Malkin, V. M.; Toroker, Z.; Khazanov, E. A.; Sergeev, A. M.; TAJIMA, T.

    2011-01-01

    A new amplification method, weaving the three basic compression techniques, Chirped Pulse Amplification (CPA), Optical Parametric Chirped Pulse Amplification (OPCPA) and Plasma Compression by Backward Raman Amplification (BRA) in plasma, is proposed. It is called C3 for Cascaded Conversion Compression. It has the capability to compress with good efficiency kilojoule to megajoule, nanosecond laser pulses into femtosecond pulses, to produce exawatt and beyond peak power. In the future, C3 could...

  19. Mapping strategies: Chromosome 16 workshop

    Energy Technology Data Exchange (ETDEWEB)

    1989-01-01

    The following topics from a workshop on chromosome 16 are briefly discussed: genetic map of chromosome 16; chromosome breakpoint map of chromosome 16; integrated physical/genetic map of chromosome 16; pulsed field map of the 16p13.2--p13.3 region (3 sheets); and a report of the HGM10 chromosome 16 committee.

  20. Virtual Workshop

    DEFF Research Database (Denmark)

    Buus, Lillian; Bygholm, Ann

    In relation to the Tutor course in the Mediterranean Virtual University (MVU) project, a virtual workshop “Getting experiences with different synchronous communication media, collaboration, and group work” was held with all partner institutions in January 2006. More than 25 key-tutors within MVU...... participated from different institutions in the workshop. The result of the workshop was experiences with different communication tools and media. Facing the difficulties and possibilities in collaborateting virtually concerned around group work and development of a shared presentation. All based on getting...... experiences for the learning design of MVU courses. The workshop intented to give the participants the possibility to draw their own experiences with issues on computer supported collaboration, group work in a virtual environment, synchronous and asynchronous communication media, and different perspectives...

  1. Workshop Proceedings

    DEFF Research Database (Denmark)

    2012-01-01

    , the main focus there is on spoken languages in their written and spoken forms. This series of workshops, however, offers a forum for researchers focussing on sign languages. For the third time, the workshop had sign language corpora as its main topic. This time, the focus was on the interaction between......This collection of papers stems from the Fifth Workshop on the Representation and Processing of Sign Languages, held in May 2012 as a satellite to the Language Resources and Evaluation Conference in Istanbul. While there has been occasional attention for sign languages at the main LREC conference...... corpus and lexicon. More than half of the papers presented contribute to this topic. Once again, the papers at this workshop clearly identify the potentials of even closer cooperation between sign linguists and sign language engineers, and we think it is events like this that contribute a lot to a better...

  2. All-solid-state high-repetition-rate magnetic pulse compression generator%全固态高重复频率磁脉冲压缩发生器

    Institute of Scientific and Technical Information of China (English)

    张东东; 周媛; 李文峰; 许家雨; 王珏; 邵涛; 赵莹; 徐蓉

    2012-01-01

    The paper presents an all-solid-state high-repetition-rate pulse generator with adjustable output amplitude based on magnetic pulse compression (MPC) technique. The pulse compression network makes use of commercially available IGBTs switching a capacitor bank into a metglas transformer together with a voltage doubling circuit. The capacitor bank is charged to 500 V by a resonant LC charger, and also switched by a commercial diode. The output of the pulse generator is controlled by the gate voltage of the IGBTs. Pulses with a width of 70 ns can be generated with repetition rates up to 5 kHz. The amplitude can be controlled from 4 kV to 40 kV into a 500 Ω load. Equivalent circuits for the final operation stage of the compressor accounting for pre-pulse in magnetic switches are presented and analyzed, and the pre-pulse generation process of the MPC system is discussed. Simulation results show that, increasing the unsaturated inductance of the magnetic switch and reducing the load resistance enhance the pre-pulse peak. Thus to diminish the pre-pulse, a better ferrite core with higher permeability should be considered.%设计制作了全固态高重复频率磁脉冲压缩发生器,最高重复频率5 kHz,脉宽70 ns,通过调节初始储能电容上的电压可在500 Ω阻性负载上获得4~40 kV连续可调的输出电压.通过分析简化的磁压缩末级回路,分析了预脉冲产生的过程,得出了预脉冲的电压表达式,选取适当的磁芯相对磁导率,经过求解,得出在磁开关未饱和电感一定时预脉冲随负载阻值变化的曲线簇,从曲线中可以看出:随着负载的阻值的增大,预脉冲的峰值绝对值也增大;在负载恒定的情况下,增大磁开关未饱和电感的大小可以显著地减小负载两端预脉冲的峰值绝对值,这要求磁开关磁芯有更高的相对磁导率.

  3. Cascaded quadratic soliton compression at 800 nm

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Moses, Jeffrey;

    2007-01-01

    We study soliton compression in quadratic nonlinear materials at 800 nm, where group-velocity mismatch dominates. We develop a nonlocal theory showing that efficient compression depends strongly on characteristic nonlocal time scales related to pulse dispersion.......We study soliton compression in quadratic nonlinear materials at 800 nm, where group-velocity mismatch dominates. We develop a nonlocal theory showing that efficient compression depends strongly on characteristic nonlocal time scales related to pulse dispersion....

  4. Image data compression investigation

    Science.gov (United States)

    Myrie, Carlos

    1989-01-01

    NASA continuous communications systems growth has increased the demand for image transmission and storage. Research and analysis was conducted on various lossy and lossless advanced data compression techniques or approaches used to improve the efficiency of transmission and storage of high volume stellite image data such as pulse code modulation (PCM), differential PCM (DPCM), transform coding, hybrid coding, interframe coding, and adaptive technique. In this presentation, the fundamentals of image data compression utilizing two techniques which are pulse code modulation (PCM) and differential PCM (DPCM) are presented along with an application utilizing these two coding techniques.

  5. Digital Poly-phase Filtering and Pulse Compression of PN-code Fuze%伪码引信的数字多相滤波和频域脉冲压缩

    Institute of Scientific and Technical Information of China (English)

    徐利平; 谢锡海; 曹志谦; 郑小燕

    2009-01-01

    In order to overcome the shortcoming of the time-domain correlation processing in classical PN-code fuze, the method of digital quadrature detection is proposed based on poly-phase filtering and digital pulse com-pression which are achieved by FPGA and DSP tools. The FPGA-DSP simulation results are indicated to be accu-rate according to the comparison with the results simulated by the MATLAB. Digital pulse compression tech-nique will be the trend of modern pulse compression technique because of its stable performance, strong anti-in-terference ability, flexible control mode and miniaturized hardware system.%针对传统伪随机码引信对回波信号时域相关处理法在处理大点数、大压缩比信号时的不足,提出采用软件无线电技术中的多相滤波数字正交检波器和频域数字脉冲压缩的方法.分别使用FPGA和DSP实现多相滤波数字正交检波器以及频域数字脉冲压缩.对FPGA及DSP进行的仿真与Matlab对整个过程仿真的结果比较,误差极小,验证了理论的正确性.数字脉压技术以其性能稳定、抗干扰能力强、控制方式灵活和硬件系统小型化等优点,逐步取代早期的模拟脉压技术,是现代脉压技术的发展趋势.

  6. 不同周期载频调制二进制编码激励脉冲压缩仿真研究%Simulation Study on Pulse Compression by Bi-phase Coded Excitation with Carrier Modulation

    Institute of Scientific and Technical Information of China (English)

    吴何珍; 刘政一

    2013-01-01

    In order to introduce the digital encoded technology to the seismic detection, the author studied coded excitation digital simulation and grasped the rules and characters of coded excitation, which is based on the basic coded excitation principle. By modulation launching of coded excitation signal, the author also did simulation research on pulse compression of received signal. Furthermore, the author processed pulse compression with 13 bit signal excitation transducer with one to five units code element (by launching of 13 bit signal excitation transducer with one to five units code element). The author did the power spectrum analyses and analyzed the influence on different excitation signal and its pulse compression result by transducer.%本文为将编码技术引入地震探测中,在分析编码激励基本原理的基础上,开展了编码激励的数值模拟研究,掌握编码激励的规律和特点.通过激励编码信号的调制发射,对接收信号进行脉冲压缩的仿真研究.其次通过单位码元载有1至5个载频周期个数的13位Barker码调制信号激励换能器(通过发射载有1至5个载频周期的13位Barker码调制信号来激励换能器),对接收信号进行脉冲压缩仿真研究和频谱分析,分析了换能器性能对编码激励信号及其脉冲压缩结果的影响.

  7. Network workshop

    DEFF Research Database (Denmark)

    Bruun, Jesper; Evans, Robert Harry

    2014-01-01

    research community. With this workshop, participants were offered a way into network science based on authentic educational research data. The workshop was constructed as an inquiry lesson with emphasis on user autonomy. Learning activities had participants choose to work with one of two cases of networks......This paper describes the background for, realisation of and author reflections on a network workshop held at ESERA2013. As a new research area in science education, networks offer a unique opportunity to visualise and find patterns and relationships in complicated social or academic network data....... These include student relations and interactions and epistemic and linguistic networks of words, concepts and actions. Network methodology has already found use in science education research. However, while networks hold the potential for new insights, they have not yet found wide use in the science education...

  8. Network workshop

    DEFF Research Database (Denmark)

    Bruun, Jesper; Evans, Robert Harry

    2014-01-01

    This paper describes the background for, realisation of and author reflections on a network workshop held at ESERA2013. As a new research area in science education, networks offer a unique opportunity to visualise and find patterns and relationships in complicated social or academic network data....... These include student relations and interactions and epistemic and linguistic networks of words, concepts and actions. Network methodology has already found use in science education research. However, while networks hold the potential for new insights, they have not yet found wide use in the science education...... research community. With this workshop, participants were offered a way into network science based on authentic educational research data. The workshop was constructed as an inquiry lesson with emphasis on user autonomy. Learning activities had participants choose to work with one of two cases of networks...

  9. Poetry Workshop.

    Science.gov (United States)

    Janeczko, Paul B.

    2000-01-01

    This workshop offers activities to teach students about poetry. After describing haiku as a brief snapshot rather than a story, it explains how to teach poetry using an attached reproducible and poster. The tear-out reproducible sheet teaches students how to write their own haiku, offering a sample one as a model. The poster presents three sample…

  10. 基于压缩感知的频率编码脉冲雷达高分辨距离成像方法%High Resolution Range Imaging Method for Frequency-coded Pulse Radar Based on Compressive Sensing

    Institute of Scientific and Technical Information of China (English)

    贺亚鹏; 庄珊娜; 李洪涛; 朱晓华

    2011-01-01

    A novel Compressive Sensing (CS) based high resolution target range imaging method for Frequency-Coded Pulse Radar (FCPR) is proposed in this paper. Considering spatial sparsity of the target scene, a FCPR target sparse signal model is derived. A FCPR pulses coherent synthesis processing method is presented. Target frequency domain response is sampled with only a few FCPR sub-pulses, from which target high resolution range information is reconstructed exactly. A dynamic creation of deduced dimension sensing matrix based on target velocity pre-estimation using FFT is proposed. This method reduces the computational complexity of CS recovery algorithms and promotes the speed of CS based FCPR pulses coherent synthesis processing. Computer simulations show that the presented method performs better than traditional IFFT pulses coherent synthesis processing algorithm with smaller magnitude estimation error of strong target scattering center and better robustness against velocity estimation error and noise.%针对频率编码脉冲雷达(Frequency-Coded Pulse Radar,FCPR),该文提出一种基于压缩感知(Compressive Sensing,cs)的目标高分辨距离成像方法.利用目标场景的空间稀疏性,建立FCPR目标回波稀疏信号模型,提出 基于CS的FCPR脉冲相参合成处理方法.该方法采用少量FCPR信号子脉冲对目标频域响应进行采样,即可提取目标高分辨距离像信息.为了降低CS重构算法的运算复杂度,提出一种基于FFT目标速度预估计的动态构造降维感知矩阵的方法,提高了采用CS进行FCPR脉冲相参合成处理的速度.仿真结果表明该方法较传统IFFT脉冲相干合成算法具有更小的目标强散射中心幅度估计误差,对速度估计误差及噪声的鲁棒性更好.

  11. Advances in compressible turbulent mixing

    Energy Technology Data Exchange (ETDEWEB)

    Dannevik, W.P.; Buckingham, A.C.; Leith, C.E. [eds.

    1992-01-01

    This volume includes some recent additions to original material prepared for the Princeton International Workshop on the Physics of Compressible Turbulent Mixing, held in 1988. Workshop participants were asked to emphasize the physics of the compressible mixing process rather than measurement techniques or computational methods. Actual experimental results and their meaning were given precedence over discussions of new diagnostic developments. Theoretical interpretations and understanding were stressed rather than the exposition of new analytical model developments or advances in numerical procedures. By design, compressibility influences on turbulent mixing were discussed--almost exclusively--from the perspective of supersonic flow field studies. The papers are arranged in three topical categories: Foundations, Vortical Domination, and Strongly Coupled Compressibility. The Foundations category is a collection of seminal studies that connect current study in compressible turbulent mixing with compressible, high-speed turbulent flow research that almost vanished about two decades ago. A number of contributions are included on flow instability initiation, evolution, and transition between the states of unstable flow onset through those descriptive of fully developed turbulence. The Vortical Domination category includes theoretical and experimental studies of coherent structures, vortex pairing, vortex-dynamics-influenced pressure focusing. In the Strongly Coupled Compressibility category the organizers included the high-speed turbulent flow investigations in which the interaction of shock waves could be considered an important source for production of new turbulence or for the enhancement of pre-existing turbulence. Individual papers are processed separately.

  12. The subband pulse compression method based on quadratture mirror filter (QMF) banks%基于正交镜像滤波器组的子带脉冲压缩方法

    Institute of Scientific and Technical Information of China (English)

    高翠翠; 林明; 钱春雷

    2015-01-01

    针对超宽带雷达频带分割滤波器不理想、导致子带脉冲压缩和直接脉冲压缩结果相差较大的问题,本文提出了基于正交镜像滤波器组的子带脉冲压缩方法。首先设计了近似完全重建的正交镜像滤波器组,定义目标函数为通带误差、阻带能量和失真转移函数平方误差的加权和,通过无约束的变尺度方法将其最小化,然后用设计的正交镜像滤波器作为频带分割滤波器,实现子带脉冲压缩。仿真结果表明,本文设计的正交镜像滤波器组,相比现有的设计,具有更小的峰值重建误差、通带和阻带误差。提出的子带脉冲压缩方法,与传统方法相比,主副瓣比和主瓣宽度等脉压性能也明显提高。%For the problem that ultra-wideband (UWB)radar channel dropping filter isn′t ideal, which causes big error between subband pulse compression and direct pulse compression, a new method of subband pulse compression of UWB radar is presented. In the new method, nearly perfect-reconstruction two-channel quadrature mirror filter banks is designed at first. The objective function is formulated as a weighted sum of pass-band error and stop-band residual energy of low-pass prototype filter , and the square error of the distortion transfer function, which is minimized by unconstrained indirect update optimization method. The QMF replaces channel dropping filter. Compared with traditional subband pulse pressure method, simulation results show that the mainlobe to sidelobe and mainlobe width in proposed method are improved obviously.

  13. A 158 fs 5.3 nJ fiber-laser system at 1 mu m using photonic bandgap fibers for dispersion control and pulse compression

    DEFF Research Database (Denmark)

    Nielsen, C.K.; Jespersen, Kim Giessmann; Keiding, S.R.

    2006-01-01

    We demonstrate a 158 fs 5.3 nJ mode-locked laser system based on a fiber oscillator, fiber amplifier and fiber compressor. Dispersion compensation in the fiber oscillator was obtained with a solid-core photonic bandgap (SC-PBG) fiber spliced to standard fibers, and external compression is obtaine...

  14. Workshop on accelerator magnet superconductors. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The workshop on accelerator magnet superconductors has gathered 102 registered participants from research laboratories, universities and industry. 8 European companies, active in superconducting materials and cables were present. This workshop has been organized to deal with the status of the world research and development on superconducting materials and cables for high field magnets (B > 10 T). The workshop has also reviewed the status of high temperature superconductors and transmission line cables for potential use in low field superconducting magnets for injectors and beam transfer lines, as well as cables for pulsed magnets that might be used in future hadron colliders or injectors.

  15. Creating Fantastic PI Workshops

    Energy Technology Data Exchange (ETDEWEB)

    Biedermann, Laura B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clark, Blythe G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Colbert, Rachel S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dagel, Amber Lynn [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gupta, Vipin P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hibbs, Michael R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Perkins, David Nikolaus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); West, Roger Derek [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    The goal of this SAND report is to provide guidance for other groups hosting workshops and peerto-peer learning events at Sandia. Thus this SAND report provides detail about our team structure, how we brainstormed workshop topics and developed the workshop structure. A Workshop “Nuts and Bolts” section provides our timeline and check-list for workshop activities. The survey section provides examples of the questions we asked and how we adapted the workshop in response to the feedback.

  16. Workshop experience

    Directory of Open Access Journals (Sweden)

    Georgina Holt

    2007-04-01

    Full Text Available The setting for the workshop was a heady mix of history, multiculturalism and picturesque riverscapes. Within the group there was, as in many food studies, a preponderance of female scientists (or ethnographers, but the group interacted on lively, non-gendered terms - focusing instead on an appreciation of locals food and enthusiasm for research shared by all, and points of theoretical variance within that.The food provided by our hosts was of the very highest eating and local food qualities...

  17. Recent Workshops

    CERN Multimedia

    Wickens, F. J.

    Since the previous edition of ATLAS e-news, the NIKHEF Institute in Amsterdam has hosted not just one but two workshops related to ATLAS TDAQ activities. The first in October was dedicated to the Detector Control System (DCS). Just three institutes, CERN, NIKHEF and St Petersburg, provide the effort for the central DCS services, but each ATLAS sub-detector provides effort for their own controls. Some 30 people attended, including representatives for all of the ATLAS sub-detectors, representatives of the institutes working on the central services and the project leader of JCOP, which brings together common aspects of detector controls across the LHC experiments. During the three-day workshop the common components were discussed, and each sub-detector described their experiences and plans for their future systems. Whilst many of the components to be used are standard commercial components, a key custom item for ATLAS is the ELMB (Embedded Local Monitor Board). Prototypes for this have now been extensively test...

  18. "Compressed" Compressed Sensing

    CERN Document Server

    Reeves, Galen

    2010-01-01

    The field of compressed sensing has shown that a sparse but otherwise arbitrary vector can be recovered exactly from a small number of randomly constructed linear projections (or samples). The question addressed in this paper is whether an even smaller number of samples is sufficient when there exists prior knowledge about the distribution of the unknown vector, or when only partial recovery is needed. An information-theoretic lower bound with connections to free probability theory and an upper bound corresponding to a computationally simple thresholding estimator are derived. It is shown that in certain cases (e.g. discrete valued vectors or large distortions) the number of samples can be decreased. Interestingly though, it is also shown that in many cases no reduction is possible.

  19. MICCAI Workshops

    CERN Document Server

    Nedjati-Gilani, Gemma; Venkataraman, Archana; O'Donnell, Lauren; Panagiotaki, Eleftheria

    2014-01-01

    This volume contains the proceedings from two closely related workshops: Computational Diffusion MRI (CDMRI’13) and Mathematical Methods from Brain Connectivity (MMBC’13), held under the auspices of the 16th International Conference on Medical Image Computing and Computer Assisted Intervention, which took place in Nagoya, Japan, September 2013. Inside, readers will find contributions ranging from mathematical foundations and novel methods for the validation of inferring large-scale connectivity from neuroimaging data to the statistical analysis of the data, accelerated methods for data acquisition, and the most recent developments on mathematical diffusion modeling. This volume offers a valuable starting point for anyone interested in learning computational diffusion MRI and mathematical methods for brain connectivity as well as offers new perspectives and insights on current research challenges for those currently in the field. It will be of interest to researchers and practitioners in computer science, ...

  20. Generation of few-cycle terawatt light pulses using optical parametric chirped pulse amplification.

    Science.gov (United States)

    Witte, S; Zinkstok, R; Hogervorst, W; Eikema, K

    2005-06-27

    We demonstrate the generation of 9.8+/-0.3 fs laser pulses with a peak power exceeding one terawatt at 30 Hz repetition rate, using optical parametric chirped pulse amplification. The amplifier is pumped by 140 mJ, 60 ps pulses at 532 nm, and amplifies seed pulses from a Ti:Sapphire oscillator to 23 mJ/pulse, resulting in 10.5 mJ/pulse after compression while amplified fluorescence is kept below 1%. We employ grating-based stretching and compression in combination with an LCD phase-shaper, allowing compression close to the Fourier limit of 9.3 fs.

  1. Low-loss polarization-maintaining fusion splicing of single-mode fibers and hollow-core photonic crystal fibers, relevant for monolithic fiber laser pulse compression

    DEFF Research Database (Denmark)

    Kristensen, Jesper Toft; Houmann, Andreas; Liu, Xiaomin;

    2008-01-01

    B. The reciprocal HC-PCF-to-PM-SMF splice loss is found to be 2.19 ± 0.33 dB, which is caused by the mode evolution in HC-PCF. The return loss in both cases was measured to be −14 dB. We show that a splice defect is caused by the HC-PCF cleave defect, and the lossy splice can be predicted at an early stage...... of the splicing process. We also demonstrate that the higher splice loss compromises the PM properties of the splice. Our splicing technique was successfully applied to the realization of a low-loss, environmentally stable monolithic PM fiber laser pulse compressor, enabling direct end-of-the-fiber femtosecond...

  2. Pulse combustion: an assessment of opportunities for increased efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Brenchley, D.L.; Bomelburg, H.J.

    1984-12-01

    The results of a literature review on pulse combustion are discussed. Current, near-future, and potential opportunities for pulse combustion applications are summarized, and the barriers to developing and using pulse combustion technology are discussed, along with research and development needs. Also provided are the proceedings of a pulse combustion workshop held in May, 1984 in Seattle, Washington. (LEW)

  3. Compressive myelopathy in fluorosis: MRI

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K. [MR Section, Department of Radiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow-226014 (India); Agarwal, P. [MR Section, Department of Radiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow-226014 (India); Kumar, S. [MR Section, Department of Radiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow-226014 (India); Surana, P.K. [Department of Neurology, SGPGIMS, Lucknow-226014 (India); Lal, J.H. [MR Section, Department of Radiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow-226014 (India); Misra, U.K. [Department of Neurology, SGPGIMS, Lucknow-226014 (India)

    1996-05-01

    We examined four patients with fluorosis, presenting with compressive myelopathy, by MRI, using spin-echo and fast low-angle shot sequences. Cord compression due to ossification of the posterior longitudinal ligament (PLL) and ligamentum flavum (LF) was demonstrated in one and ossification of only the LF in one. Marrow signal was observed in the PLL and LF in all the patients on all pulse sequences. In patients with compressive myelopathy secondary to ossification of PLL and/or LF, fluorosis should be considered as a possible cause, especially in endemic regions. (orig.). With 2 figs., 1 tab.

  4. A wide-band measurement method for transmission coefficients based on pulse compression technique%基于脉冲压缩技术的宽带透射系数测量方法

    Institute of Scientific and Technical Information of China (English)

    于盛齐; 黄益旺; 吴琼

    2013-01-01

    Transmission coefficient is one of the most significant parameters of underwater acoustic materials. In order to measure a transmission coefficient in a tank, a method based on pulse compression technique was proposed. With it, a directive wave was extracted from a compressed signal. The method could overcome unavoidable multi-path disturbance in tests, and easily obtain transmission coefficients for all the frequencies in the measured frequency band simultaneously, i. e. , a wide-band measurement was realized. This method was verified through comparison between the results of narrow and wide-band measurements of a glass box, they were conducted in the frequency range of 20 ~60 kHz in a tank.%透射系数是水声材料的一项重要声学参数,为在水池中对水声材料的透射系数进行测量,提出基于脉冲压缩技术的测量方法,对接收信号进行压缩提取直达波.该方法不仅能克服实验过程中经常遇到的多途干扰,且测量过程简单,可同时获得测量频带内所有频点的透射系数,实现对透射系数的宽带测量.在水池环境下,通过对20 ~60 kHz频率范围内玻璃缸的窄带测量与宽带测量结果比较,验证该方法的有效性.

  5. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality...... a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, an anthropomorfized archive of a past intimacy and an all-encompassing immersive environment modulating continuously in real space-time....

  6. Ultra-short laser pulse compression by using the group-velocity-matched cascaded quadratic nonlinearity∗%利用群速度匹配的级联二阶非线性实现超短激光脉冲压缩*

    Institute of Scientific and Technical Information of China (English)

    叶荣; 张彬; 李恪宇

    2013-01-01

      提出了一种采用倾斜脉冲的级联二阶非线性来实现超短激光脉冲压缩的方法.对基于单块BBO晶体中基频光与倍频光群速度匹配的级联二阶非线性的脉冲压缩方案进行了理论分析.对比研究了群速度匹配与失配情况下利用级联二阶非线性进行脉冲压缩的效果,并模拟分析了基频光与倍频光的位相失配量、非线性晶体长度、基频光初始峰值光强和初始脉宽等因素对脉冲压缩效果的影响.结果表明,基频光与倍频光的群速度匹配将会大幅度改善压缩脉冲的时间波形和频谱分布.通过对位相失配量、晶体长度、初始光强等参数的优化和选取可获得较理想的压缩效果.采用倾斜脉冲的级联二阶非线性的脉宽压缩方法,针对中心波长800 nm、脉宽100 fs,峰值光强为50 GW/cm2的基频光脉冲,采用25 mm厚BBO晶体,当基频光与倍频光位相失配量∆k=60 mm−1(对应失谐角1.98◦),晶体外部脉冲前沿倾斜角γ0=74◦时,计算获得了质量较好的20 fs剩余基频光,并同时产生了14 fs的倍频光.%A new method for compressing ultra-short laser pulse has been proposed in which cascaded quadratic nonlinearity with tilt pulse is used. The pulse compression scheme with group velocity matching between fundamental harmonic (FH) and second harmonic (SH) pulses in a single BBO crystal has been analyzed theoretically. The compressed results have been investigated and compared between the cases of group velocity matching and mismatching. Furthermore, the influences of the phase mismatching between the FH and SH pulses, the length of the nonlinear crystal, the initial peak intensity and pulse-duration of the FH pulse on the pulse-duration compression have been analyzed and simulated. The results show that the matched group velocity between FH and SH pulses can improve significantly both the temporal profile and the spectrum distribution of the compressed pulse. High

  7. High-energy pulse compressor using self-defocusing spectral broadening in anomalously dispersive media

    DEFF Research Database (Denmark)

    2015-01-01

    A method and a pulse compressor (1) for compressing an optical pulse, wherein the pulse compressor comprising a bulk quadratic nonlinear medium (2) adapted for generating a negative nonlinear phase variation on the optical pulse and having a negative group-velocity dispersion, and a dispersive un...... subsequently be compressed by providing normal dispersion. As KDP crystals can be glued together, large apertures of the pulse compressor are possible making this method suitable for pulse compression in Joule-class lasers....

  8. Optimised design of fibre-based pulse compressor for gain-switched DFB laser pulses at 1.5 µm

    OpenAIRE

    Barry, Liam P.; Thomsen, Benn C.; Dudley, John M.; Harvey, John D.

    1999-01-01

    An optical-fibre based pulse compressor for gain-switched DFB laser pulses has been optimised using a systematic procedure based on the initial complete characterisation of the laser pulses, followed by numerical simulations of the pulse propagation in different types of fibre to determine the required lengths for optimum compression. Using both linear and nonlinear compression techniques, an optimum compression factor of 12 is achieved.

  9. Workshops as a Research Methodology

    Science.gov (United States)

    Ørngreen, Rikke; Levinsen, Karin

    2017-01-01

    This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice, and workshops as a research methodology. Focusing primarily on…

  10. IPHE Infrastructure Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-02-01

    This proceedings contains information from the IPHE Infrastructure Workshop, a two-day interactive workshop held on February 25-26, 2010, to explore the market implementation needs for hydrogen fueling station development.

  11. Dynamic parabolic pulse generation using temporal shaping of wavelength to time mapped pulses.

    Science.gov (United States)

    Nguyen, Dat; Piracha, Mohammad Umar; Mandridis, Dimitrios; Delfyett, Peter J

    2011-06-20

    Self-phase modulation in fiber amplifiers can significantly degrade the quality of compressed pulses in chirped pulse amplification systems. Parabolic pulses with linear frequency chirp are suitable for suppressing nonlinearities, and to achieve high peak power pulses after compression. In this paper, we present an active time domain technique to generate parabolic pulses for chirped pulse amplification applications. Pulses from a mode-locked laser are temporally stretched and launched into an amplitude modulator, where the drive voltage is designed using the spectral shape of the input pulse and the transfer function of the modulator, resulting in the generation of parabolic pulses. Experimental results of pulse shaping with a pulse train from a mode-locked laser are presented, with a residual error of less than 5%. Moreover, an extinction ratio of 27 dB is achieved, which is ideal for chirped pulse amplification applications.

  12. Fiber Optical Parametric Chirped Pulse Amplification of Sub-Picosecond Pulses

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Da Ros, Francesco

    2013-01-01

    We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs.......We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs....

  13. ICP-MS Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Carman, April J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Eiden, Gregory C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-11-01

    This is a short document that explains the materials that will be transmitted to LLNL and DNN HQ regarding the ICP-MS Workshop held at PNNL June 17-19th. The goal of the information is to pass on to LLNL information regarding the planning and preparations for the Workshop at PNNL in preparation of the SIMS workshop at LLNL.

  14. MOOC Design Workshop

    DEFF Research Database (Denmark)

    Nørgård, Rikke Toft; Mor, Yishay; Warburton, Steven

    2016-01-01

    For the last two years we have been running a series of successful MOOC design workshops. These workshops build on previous work in learning design and MOOC design patterns. The aim of these workshops is to aid practitioners in defining and conceptualising educational innovations (predominantly, ...

  15. Observation on compressive strength of veneers on mottled teeth after pulse Nd:YAG laser irradiation%氟斑牙经脉冲Nd:YAG激光照射后贴面抗压强度观察

    Institute of Scientific and Technical Information of China (English)

    夏永华; 张丹丹

    2008-01-01

    Objective To analyze experimentally the compressive strength of veneers on mottled teeth after Dul8e Nd:YAG laser irradiation.Methods Sixty motded teeth were extracted,including thirty maxdlary central incisors and thirty maxillary lateral incisors and each were divided equally into two groups randomly(experimental groups and control groups).The former were irradiated by pulse Nd:YAG lafer and then etched by 37%phosphorus acid.The latter only etched by 37%phosphorus acid.All the teeth were restored by composite resin veneers and tested with Instron 4505 electronic testing machine.The average collapse loads of the veneers of incisors were tested. The maximal compressive loads of the samples were obtained,then the experimental results were analyzed.Results The average collapse loads of central incisors of test groups and control groups were(0.342±0.053),(0.289±0.041) kN respectively,with a signiticant difference(t=3.16,P<0.05).The average collapse loads of lateral incisors of test groups and control groups were(0.321±0.041),(0.208 ±0.032)kN respectively.There was a significant difference when they were compared(t=7.66,P<0.05).Conclusions The compressive strength of the veneers incneases significandv when the mottled teeth are irradiated by pulse Nd:YAG laser.This method is worthy of recommending.%目的 观察氟斑牙经脉冲Nd:YAG激光照射后贴面的抗压强度变化.方法 取因各种原因而拔除的人上颌中切、侧切氟斑牙各30颗,每种切牙均分成试验组和对照组,每组15颗.试验组牙齿以脉冲Nd:YAG激光照射后.再以37%的磷酸酸蚀;而对照组牙齿只用37%的磷酸酸蚀,然后所有牙齿做树脂贴面,在Instron 4505电子万能试验机上进行压缩试验,测定切牙的试验组、对照组贴面的平均破坏载荷.结果 试验组和对照组中切牙贴面平均破坏载荷分别为(0.342 4-0.053)、(0.289±0.041)kN,试验组明显高于对照组,两组比较差异有统计学意义(t=3.16,P<0.05);试验

  16. Proceedings of the switched power workshop

    Energy Technology Data Exchange (ETDEWEB)

    Fernow, R.C. (ed.)

    1988-01-01

    These proceedings contain most of the presentations given at a workshop on the current state of research in techniques for switched power acceleration. The proceedings are divided, as was the workshop itself, into two parts. Part 1, contains the latest results from a number of groups active in switched power research. The major topic here is a method for switching externally supplied power onto a transmission line. Advocates for vacuum photodiode switching, solid state switching, gas switching, and synthetic pulse generation are all presented. Other important areas of research described in this section concern: external electrical and laser pulsing systems; the properties of the created electromagnetic pulse; structures used for transporting the electromagnetic pulse to the region where the electron beam is located; and possible applications. Part 2 of the proceedings considers the problem of designing a high brightness electron gun using switched power as the power source. This is an important first step in demonstrating the usefulness of switched power techniques for accelerator physics. In addition such a gun could have immediate practical importance for advanced acceleration studies since the brightness could exceed that of present sources by several orders of magnitude. I would like to take this opportunity to thank Kathleen Tuohy and Patricia Tuttle for their assistance in organizing and running the workshop. Their tireless efforts contribute greatly to a very productive meeting.

  17. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality......“Pulse on Pulse” investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006-) by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy...... of the visitor’s beating heart to the blink of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the blinking light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant...

  18. Compressive full waveform lidar

    Science.gov (United States)

    Yang, Weiyi; Ke, Jun

    2017-05-01

    To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.

  19. Cascaded Quadratic Soliton Compression in Waveguide Structures

    DEFF Research Database (Denmark)

    Guo, Hairun

    The generation of few-cycle, high-intensity laser pulses is of great interests in a variety of research and application fields such as time-resolved spectroscopy, bio-chemical imaging with two-photon absorptions, medical treatment, material characterization, coherent supercontinuum generation...... and tera-hertz wave generation. Commercial pulsed lasers including the solid state system and the pulsed fiber laser have promised the generation of energetic femto-second pulses with the temporal duration around much more than tens of femto-seconds. Therefore, pulse compression technologies could be used...

  20. Analysis on Coordination System of Fuse and Warhead of Electromagnetic Pulse Bomb With Cascaded Flux Compression%爆磁压缩电磁脉冲弹引战配合分析

    Institute of Scientific and Technical Information of China (English)

    毛超; 刘忠; 邱志明; 卢发兴

    2012-01-01

    为了提高爆磁压缩电磁脉冲弹作战使用效能,根据该弹定向辐射特点,分析了爆磁压缩电磁脉冲弹定向辐射引战配合特性,建立了电磁脉冲弹引战配合的数学模型,给出了控制电磁脉冲弹引信最佳起爆时刻的数值计算方法.通过数值优化分析,给出了弹目交会参数对定向辐射天线对准精度的影响曲线.仿真图像表明,俯仰角参数对辐射天线对准精度影响最大.研究结论可为电磁脉冲弹攻击参数的计算和战术使用提供理论依据.%To improve the operational effectiveness of electromagnetic pulse bomb(EMPB) with cascaded flux compression,the characteristics of fuse and warhead matching were analyzed based on the directed radiation property,and the coordination system of EMPB was built. Based on the coordination system, the numerical method for the optimal detonation time of the fuse was proposed. By numerical optimization, the effect of parameters of bomb encountering target on reg- istration precision of active antenna was obtained. The calculation figures show that the pitching angle is the principal factor affecting the registration precision. The numerical simulation results offer theoretic basis for setting attack parameters and tactical use of EMPB.

  1. 基于梳状谱发生器的毫米波相参脉压模拟器%A New Coherent Pulse Compressed MM-Wave Radar RF Echo Generator Based on Comb Spectrum Generator

    Institute of Scientific and Technical Information of China (English)

    翟龙军; 曲洪东; 王晓伟; 姜志森

    2014-01-01

    研制了一种基于梳状谱发生器的全相参脉冲压缩毫米波雷达目标射频回波模拟器。通过与被测雷达共用基准频率参考信号,结合梳状谱发生器及DDS,保证了输出信号和雷达发射信号的相参性和快速频率跳变,实现较好的相位噪声性能和杂散抑制。该系统输出为Ka波段,带宽2 GHz,步进100 kHz,相位噪声小于-80 dBc@1kHz,跳频时间小于2μs。%A new coherent pulse compressed mm-wave radar RF rcho generator based on comb spectrum generator was de-veloped. Using the same frequency reference signal of mm-wave radar to be tested, combined with comb spectrum genera-tor and DDS, the coherency of the output signal was ensured, and fast frequency switching performance was achieved with low noise and spurious level. The developed echo generator outputs in Ka band, with output bandwidth of 2 GHz, frequen-cy step of 100 kHz, phase noise level of-80dBc@1kHz, low spurious level of-60 dBc and fast frequency switching time of 2μs.

  2. Wellhead compression

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Joe [Sertco Industries, Inc., Okemah, OK (United States); Vazquez, Daniel [Hoerbiger Service Latin America Inc., Deerfield Beach, FL (United States); Jacobs, Denis Richard [Hoerbiger do Brasil Industria de Equipamentos, Cajamar, SP (Brazil)

    2012-07-01

    Over time, all wells experience a natural decline in oil and gas production. In gas wells, the major problems are liquid loading and low downhole differential pressures which negatively impact total gas production. As a form of artificial lift, wellhead compressors help reduce the tubing pressure resulting in gas velocities above the critical velocity needed to surface water, oil and condensate regaining lost production and increasing recoverable reserves. Best results come from reservoirs with high porosity, high permeability, high initial flow rates, low decline rates and high total cumulative production. In oil wells, excessive annulus gas pressure tends to inhibit both oil and gas production. Wellhead compression packages can provide a cost effective solution to these problems by reducing the system pressure in the tubing or annulus, allowing for an immediate increase in production rates. Wells furthest from the gathering compressor typically benefit the most from wellhead compression due to system pressure drops. Downstream compressors also benefit from higher suction pressures reducing overall compression horsepower requirements. Special care must be taken in selecting the best equipment for these applications. The successful implementation of wellhead compression from an economical standpoint hinges on the testing, installation and operation of the equipment. Key challenges and suggested equipment features designed to combat those challenges and successful case histories throughout Latin America are discussed below.(author)

  3. Compressive beamforming

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Mosegaard, Klaus

    2014-01-01

    Sound source localization with sensor arrays involves the estimation of the direction-of-arrival (DOA) from a limited number of observations. Compressive sensing (CS) solves such underdetermined problems achieving sparsity, thus improved resolution, and can be solved efficiently with convex...

  4. Exawatt-Zettawatt Pulse Generation and Applications

    CERN Document Server

    Mourou, G A; Malkin, V M; Toroker, Z; Khazanov, E A; Sergeev, A M; Tajima, T

    2011-01-01

    A new amplification method, weaving the three basic compression techniques, Chirped Pulse Amplification (CPA), Optical Parametric Chirped Pulse Amplification (OPCPA) and Plasma Compression by Backward Raman Amplification (BRA) in plasma, is proposed. It is called C3 for Cascaded Conversion Compression. It has the capability to compress with good efficiency kilojoule to megajoule, nanosecond laser pulses into femtosecond pulses, to produce exawatt and beyond peak power. In the future, C3 could be used at large-scale facilities such as the National Ignition Facility (NIF) or the Laser Megajoule (LMJ) and open the way to zettawatt level pulses. The beam will be focused to a wavelength spot size with a f#1. The very small beam size, i.e. few centimeters, along with the low laser repetition rate laser system will make possible the use of inexpensive, precision, disposable optics. The resulting intensity will approach the Schwinger value, thus opening up new possibilities in fundamental physics.

  5. Advanced Pulse Compression System and Testbed Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future space-borne cloud radars will require significant technical innovations for improving remote sensing of the Earth's atmosphere and that of other planetary...

  6. Complicated Laser Pulse Generation With Pulse Stacking for D-D ICF

    Institute of Scientific and Technical Information of China (English)

    GAO; Zhi-xing; WANG; Lei-jian; LU; Ze; ZHANG; Hai-feng

    2012-01-01

    <正>For direct drive fusion, a pre-distorted pulse with the complicated temporal shape is necessary. It is generally accepted that the pulse for shock ignition should begin with a low energy pre-pulse spike (picket) followed by a long (about 10 ns) low intensity foot pulse, which ramps up to an intermediate pedestal (compression pulse) and ends with a short high intensity spike.

  7. SPLASH'13 workshops summary

    DEFF Research Database (Denmark)

    Balzer, S.; Schultz, U. P.

    2013-01-01

    Following its long-standing tradition, SPLASH 2013 will host 19 high-quality workshops, allowing their participants to meet and discuss research questions with peers, to mature new and exciting ideas, and to build up communities and start new collaborations. SPLASH workshops complement the main t...

  8. Warehouse Sanitation Workshop Handbook.

    Science.gov (United States)

    Food and Drug Administration (DHHS/PHS), Washington, DC.

    This workshop handbook contains information and reference materials on proper food warehouse sanitation. The materials have been used at Food and Drug Administration (FDA) food warehouse sanitation workshops, and are selected by the FDA for use by food warehouse operators and for training warehouse sanitation employees. The handbook is divided…

  9. 7th International Workshop on Advanced Optical Imaging and Metrology

    CERN Document Server

    2014-01-01

    In continuation of the FRINGE Workshop Series this Proceeding contains all contributions presented at the 7. International Workshop on Advanced Optical Imaging and Metrology. The FRINGE Workshop Series is dedicated to the presentation, discussion and dissemination of recent results in Optical Imaging and Metrology. Topics of particular interest for the 7. Workshop are: - New methods and tools for the generation, acquisition, processing, and evaluation of data in Optical Imaging and Metrology (digital wavefront engineering, computational imaging, model-based reconstruction, compressed sensing, inverse problems solution) - Application-driven technologies in Optical Imaging and Metrology (high-resolution, adaptive, active, robust, reliable, flexible, in-line, real-time) - High-dynamic range solutions in Optical Imaging and Metrology (from macro to nano) - Hybrid technologies in Optical Imaging and Metrology (hybrid optics, sensor and data fusion, model-based solutions, multimodality) - New optical sensors, imagi...

  10. Workshops as a Research Methodology

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Levinsen, Karin Tweddell

    2017-01-01

    This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice, and worksh......This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice......, and workshops as a research methodology. Focusing primarily on the latter, this paper presents five studies on upper secondary and higher education teachers’ professional development and on teaching and learning through video conferencing. Through analysis and discussion of these studies’ findings, we argue...

  11. 对线性调频脉冲压缩雷达的多载波调制转发干扰%Multi-carrier Modulation Repeater Jamming against Linear Frequency Modulated Pulse-compression Radar

    Institute of Scientific and Technical Information of China (English)

    王杰贵; 张鹏程

    2015-01-01

    目前对线性调频(LFM)脉冲压缩雷达转发欺骗干扰主要通过移频调制转发和采样直接转发实现,常规转发干扰样式简单,干扰信号规律性强、复杂度低。该文提出一种基于间歇采样的多载波调制转发新型干扰样式。首先引用码片的概念对间歇采样过程重新建模,在此基础上,通过对当前采样码片附加不同移频量,结合多载波并行调制体制对其进行串并转换,利用不同次转发信号各子载波间的干扰累积,实现对LFM脉冲压缩雷达的数量、幅度、空间分布可控的逼真假目标干扰。仿真表明该干扰样式比移频干扰和直接转发干扰具有更好的干扰效果。%Repeater deception jamming against Linear Frequency Modulated (LFM) pulse-compression radar is realized by frequency-shift repeater and direct repeater jamming so far. Conventional repeater jamming type is simple. Regularity of jamming signal is strong and complexity is low. A new repeater jamming type with multi-carrier modulation based on intermittent sampling is proposed. Firstly, the model of intermittent sampling is rebuilt with the code chip concept. Based on this, lifelike false targets with the quantity, amplitude and space distribution which can be controlled are produced by attaching different frequency-shift component to the present sampling code chip, deserializing signal used multi-carrier parallel modulation system and utilizing the accumulation of different times repeater signal jamming effect among sub-carriers. The simulation results show that the new jamming type has better performance than frequency-shift jamming and direct repeater jamming.

  12. 75 FR 25281 - Food Protection Workshop; Public Workshop

    Science.gov (United States)

    2010-05-07

    ... about food safety, food defense, the regulations authorized by the Public Health Security and..., visit http://www.uark.edu/ua/foodpro/Workshops/Food_Safety_Defense_Workshop.html or contact Steven C... visit http://www.uark.edu/ua/foodpro/Workshops/Food_Safety_Defense_Workshop.html to register online...

  13. Compressive behavior of fine sand.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Bradley E. (Air Force Research Laboratory, Eglin, FL); Kabir, Md. E. (Purdue University, West Lafayette, IN); Song, Bo; Chen, Wayne (Purdue University, West Lafayette, IN)

    2010-04-01

    The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.

  14. Compression of surface myoelectric signals using MP3 encoding.

    Science.gov (United States)

    Chan, Adrian D C

    2011-01-01

    The potential of MP3 compression of surface myoelectric signals is explored in this paper. MP3 compression is a perceptual-based encoder scheme, used traditionally to compress audio signals. The ubiquity of MP3 compression (e.g., portable consumer electronics and internet applications) makes it an attractive option for remote monitoring and telemedicine applications. The effects of muscle site and contraction type are examined at different MP3 encoding bitrates. Results demonstrate that MP3 compression is sensitive to the myoelectric signal bandwidth, with larger signal distortion associated with myoelectric signals that have higher bandwidths. Compared to other myoelectric signal compression techniques reported previously (embedded zero-tree wavelet compression and adaptive differential pulse code modulation), MP3 compression demonstrates superior performance (i.e., lower percent residual differences for the same compression ratios).

  15. Magnetic Alignment of Pulsed Solenoids Using the Pulsed Wire Method

    Energy Technology Data Exchange (ETDEWEB)

    Arbelaez, D.; Madur, A.; Lipton, T.M.; Waldron, W.L.; Kwan, J.W.

    2011-04-01

    A unique application of the pulsed-wire measurement method has been implemented for alignment of 2.5 T pulsed solenoid magnets. The magnetic axis measurement has been shown to have a resolution of better than 25 {micro}m. The accuracy of the technique allows for the identification of inherent field errors due to, for example, the winding layer transitions and the current leads. The alignment system is developed for the induction accelerator NDCX-II under construction at LBNL, an upgraded Neutralized Drift Compression experiment for research on warm dense matter and heavy ion fusion. Precise alignment is essential for NDCX-II, since the ion beam has a large energy spread associated with the rapid pulse compression such that misalignments lead to corkscrew deformation of the beam and reduced intensity at focus. The ability to align the magnetic axis of the pulsed solenoids to within 100 pm of the induction cell axis has been demonstrated.

  16. Nuclear Innovation Workshops Report

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, John Howard [Idaho National Lab. (INL), Idaho Falls, ID (United States); Allen, Todd Randall [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hildebrandt, Philip Clay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Baker, Suzanne Hobbs [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    The Nuclear Innovation Workshops were held at six locations across the United States on March 3-5, 2015. The data collected during these workshops has been analyzed and sorted to bring out consistent themes toward enhancing innovation in nuclear energy. These themes include development of a test bed and demonstration platform, improved regulatory processes, improved communications, and increased public-private partnerships. This report contains a discussion of the workshops and resulting themes. Actionable steps are suggested at the end of the report. This revision has a small amount of the data in Appendix C removed in order to avoid potential confusion.

  17. Ocean margins workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-12-31

    The Department of Energy (DOE) is announcing the refocusing of its marine research program to emphasize the study of ocean margins and their role in modulating, controlling, and driving Global Change phenomena. This is a proposal to conduct a workshop that will establish priorities and an implementation plan for a new research initiative by the Department of Energy on the ocean margins. The workshop will be attended by about 70 scientists who specialize in ocean margin research. The workshop will be held in the Norfolk, Virginia area in late June 1990.

  18. 10 GHz pulse source for 640 Gbit/s OTDM based on phase modulator and self-phase modulation

    DEFF Research Database (Denmark)

    Hu, Hao; Mulvad, Hans Christian Hansen; Peucheret, Christophe

    2011-01-01

    to compensate the chirp. The non-linear pulse compression stages are based on self-phase modulation (SPM) in dispersion-flattened highly non-linear fibers (DF-HNLF). The pulse source is tunable over the C-band with negligible pedestal. © 2011 Optical Society of America....... the high pulse quality. The pulse source is based on a linear pulse compression stage followed by two polarization-independent non-linear pulse compression stages. The linear pulse compression stage relies on a phase modulator, which is used to generate linear chirp and followed by a dispersive element...

  19. Workshop on advances in smooth particle hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Wingate, C.A.; Miller, W.A.

    1993-12-31

    This proceedings contains viewgraphs presented at the 1993 workshop held at Los Alamos National Laboratory. Discussed topics include: negative stress, reactive flow calculations, interface problems, boundaries and interfaces, energy conservation in viscous flows, linked penetration calculations, stability and consistency of the SPH method, instabilities, wall heating and conservative smoothing, tensors, tidal disruption of stars, breaking the 10,000,000 particle limit, modelling relativistic collapse, SPH without H, relativistic KSPH avoidance of velocity based kernels, tidal compression and disruption of stars near a supermassive rotation black hole, and finally relativistic SPH viscosity and energy.

  20. 1995 second modulator-klystron workshop: A modulator-klystron workshop for future linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    This second workshop examined the present state of modulator design and attempted an extrapolation for future electron-positron linear colliders. These colliders are currently viewed as multikilometer-long accelerators consisting of a thousand or more RF sources with 500 to 1,000, or more, pulsed power systems. The workshop opened with two introductory talks that presented the current approaches to designing these linear colliders, the anticipated RF sources, and the design constraints for pulse power. The cost of main AC power is a major economic consideration for a future collider, consequently the workshop investigated efficient modulator designs. Techniques that effectively apply the art of power conversion, from the AC mains to the RF output, and specifically, designs that generate output pulses with very fast rise times as compared to the flattop. There were six sessions that involved one or more presentations based on problems specific to the design and production of thousands of modulator-klystron stations, followed by discussion and debate on the material.

  1. Mapping strategies: Chromosome 16 workshop. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    1989-12-31

    The following topics from a workshop on chromosome 16 are briefly discussed: genetic map of chromosome 16; chromosome breakpoint map of chromosome 16; integrated physical/genetic map of chromosome 16; pulsed field map of the 16p13.2--p13.3 region (3 sheets); and a report of the HGM10 chromosome 16 committee.

  2. Cybernetics and Workshop Design.

    Science.gov (United States)

    Eckstein, Daniel G.

    1979-01-01

    Cybernetic sessions allow for the investigation of several variables concurrently, resulting in a large volume of input compacted into a concise time frame. Three session questions are reproduced to illustrate the variety of ideas generated relative to workshop design. (Author)

  3. Complex Flow Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-05-01

    This report documents findings from a workshop on the impacts of complex wind flows in and out of wind turbine environments, the research needs, and the challenges of meteorological and engineering modeling at regional, wind plant, and wind turbine scales.

  4. Workshop: Teaching Primitive Arts.

    Science.gov (United States)

    Jordison, Jerry

    1999-01-01

    Discusses the concrete and spiritual aspects of teaching workshops on survival skills or primitive arts. Gives details on lostproofing, or ways to teach a child not to get lost in the outdoors; building a survival shelter; and wilderness cooking. (CDS)

  5. Printed Spacecraft Workshop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objectives of this workshop are to engage the engineering community at JPL that is knowledgeable in this technology in guiding/developing/critiquing  its...

  6. Waterfowl identification workshops

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Summary of waterfowl identification workshops conducted by Upper Souris National Wildlife Refuge and J. Clark Salyer National Wildlife Refuge. Objectives of the...

  7. Urban Waters Workshop

    Science.gov (United States)

    This page will house information leading up to the 2017 Urban Waters National Training Workshop. The agenda, hotel and other quarterly updates will be posted to this page including information about how to register.

  8. Transportation Management Workshop: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-01

    This report is a compilation of discussions presented at the Transportation Management Workshop held in Gaithersburg, Maryland. Topics include waste packaging, personnel training, robotics, transportation routing, certification, containers, and waste classification.

  9. Compressive Transient Imaging

    KAUST Repository

    Sun, Qilin

    2017-04-01

    High resolution transient/3D imaging technology is of high interest in both scientific research and commercial application. Nowadays, all of the transient imaging methods suffer from low resolution or time consuming mechanical scanning. We proposed a new method based on TCSPC and Compressive Sensing to achieve a high resolution transient imaging with a several seconds capturing process. Picosecond laser sends a serious of equal interval pulse while synchronized SPAD camera\\'s detecting gate window has a precise phase delay at each cycle. After capturing enough points, we are able to make up a whole signal. By inserting a DMD device into the system, we are able to modulate all the frames of data using binary random patterns to reconstruct a super resolution transient/3D image later. Because the low fill factor of SPAD sensor will make a compressive sensing scenario ill-conditioned, We designed and fabricated a diffractive microlens array. We proposed a new CS reconstruction algorithm which is able to denoise at the same time for the measurements suffering from Poisson noise. Instead of a single SPAD senor, we chose a SPAD array because it can drastically reduce the requirement for the number of measurements and its reconstruction time. Further more, it not easy to reconstruct a high resolution image with only one single sensor while for an array, it just needs to reconstruct small patches and a few measurements. In this thesis, we evaluated the reconstruction methods using both clean measurements and the version corrupted by Poisson noise. The results show how the integration over the layers influence the image quality and our algorithm works well while the measurements suffer from non-trival Poisson noise. It\\'s a breakthrough in the areas of both transient imaging and compressive sensing.

  10. AAAI-07 Workshop Reports

    OpenAIRE

    Anand, Sarabjot Singh; Bahls, Daniel; Burghart, Catherina R.; Burstein, Mark; Chen, Huajun; Collins, John; Dietterich, Tom; Doyle, Jon; Drummond, Chris; Elazmeh, William; Geib, Christopher; Goldsmith, Judy; Guesgen, Hans W.; Hendler, Jim; Jannach, Dietmar

    2007-01-01

    The AAAI-07 workshop program was held Sunday and Monday, July 22-23, in Vancouver, British Columbia, Canada. The program included the following thirteen workshops: (1) Acquiring Planning Knowledge via Demonstration; (2) Configuration; (3) Evaluating Architectures for Intelligence; (4) Evaluation Methods for Machine Learning; (5) Explanation-Aware Computing; (6) Human Implications of Human-Robot Interaction; (7) Intelligent Techniques for Web Personalization; (8) Plan, Activity, and Intent Rec...

  11. A Workshop that Works

    CERN Document Server

    Yunes, Nicolas

    2014-01-01

    The main goal of a scientific workshop is to bring together experts in a specific field or related fields to collaborate, to discuss, and to creatively make progress in a particular area. The organizational aspects of such a meeting play a critical role in achieving these goals. We here present suggestions from scientists to scientists that hopefully help in organizing a successful scientific workshop that maximizes collaboration and creativity.

  12. Workshop I: Gender Studies

    Science.gov (United States)

    Hennessey, Eden; Kurup, Anitha; Meza-Montes, Lilia; Shastri, Prajval; Ghose, Shohini

    2015-12-01

    Participants in the Gender Studies workshop of the 5th IUPAP International Conference on Women in Physics discussed the gender question in science practice from a policy perspective, informed by investigations from the social science disciplines. The workshop's three sessions—"Equity and Education: Examining Gender Stigma in Science," "A Comparative Study of Women Scientists and Engineers: Experiences in India and the US," and "Toward Gender Equity Through Policy: Characterizing the Social Impact of Interventions—are summarized, and the resulting recommendations presented.

  13. Industrial Fuel Flexibility Workshop

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2006-09-01

    On September 28, 2006, in Washington, DC, ITP and Booz Allen Hamilton conducted a fuel flexibility workshop with attendance from various stakeholder groups. Workshop participants included representatives from the petrochemical, refining, food and beverage, steel and metals, pulp and paper, cement and glass manufacturing industries; as well as representatives from industrial boiler manufacturers, technology providers, energy and waste service providers, the federal government and national laboratories, and developers and financiers.

  14. An efficient medical image compression scheme.

    Science.gov (United States)

    Li, Xiaofeng; Shen, Yi; Ma, Jiachen

    2005-01-01

    In this paper, a fast lossless compression scheme is presented for the medical image. This scheme consists of two stages. In the first stage, a Differential Pulse Code Modulation (DPCM) is used to decorrelate the raw image data, therefore increasing the compressibility of the medical image. In the second stage, an effective scheme based on the Huffman coding method is developed to encode the residual image. This newly proposed scheme could reduce the cost for the Huffman coding table while achieving high compression ratio. With this algorithm, a compression ratio higher than that of the lossless JPEG method for image can be obtained. At the same time, this method is quicker than the lossless JPEG2000. In other words, the newly proposed algorithm provides a good means for lossless medical image compression.

  15. Simulated performance results of the OMV video compression telemetry system

    Science.gov (United States)

    Ingels, Frank; Parker, Glenn; Thomas, Lee Ann

    The control system of NASA's Orbital Maneuvering Vehicle (OMV) will employ range/range-rate radar, a forward command link, and a compressed video return link. The video data is compressed by sampling every sixth frame of data; a rate of 5 frames/sec is adequate for the OMV docking speeds. Further axial compression is obtained, albeit at the expense of spatial resolution, by averaging adjacent pixels. The remaining compression is achieved on the basis of differential pulse-code modulation and Huffman run-length encoding. A concatenated error-correction coding system is used to protect the compressed video data stream from channel errors.

  16. Compressive Sensing Over Networks

    CERN Document Server

    Feizi, Soheil; Effros, Michelle

    2010-01-01

    In this paper, we demonstrate some applications of compressive sensing over networks. We make a connection between compressive sensing and traditional information theoretic techniques in source coding and channel coding. Our results provide an explicit trade-off between the rate and the decoding complexity. The key difference of compressive sensing and traditional information theoretic approaches is at their decoding side. Although optimal decoders to recover the original signal, compressed by source coding have high complexity, the compressive sensing decoder is a linear or convex optimization. First, we investigate applications of compressive sensing on distributed compression of correlated sources. Here, by using compressive sensing, we propose a compression scheme for a family of correlated sources with a modularized decoder, providing a trade-off between the compression rate and the decoding complexity. We call this scheme Sparse Distributed Compression. We use this compression scheme for a general multi...

  17. Technique for chest compressions in adult CPR

    Directory of Open Access Journals (Sweden)

    Rajab Taufiek K

    2011-12-01

    Full Text Available Abstract Chest compressions have saved the lives of countless patients in cardiac arrest as they generate a small but critical amount of blood flow to the heart and brain. This is achieved by direct cardiac massage as well as a thoracic pump mechanism. In order to optimize blood flow excellent chest compression technique is critical. Thus, the quality of the delivered chest compressions is a pivotal determinant of successful resuscitation. If a patient is found unresponsive without a definite pulse or normal breathing then the responder should assume that this patient is in cardiac arrest, activate the emergency response system and immediately start chest compressions. Contra-indications to starting chest compressions include a valid Do Not Attempt Resuscitation Order. Optimal technique for adult chest compressions includes positioning the patient supine, and pushing hard and fast over the center of the chest with the outstretched arms perpendicular to the patient's chest. The rate should be at least 100 compressions per minute and any interruptions should be minimized to achieve a minimum of 60 actually delivered compressions per minute. Aggressive rotation of compressors prevents decline of chest compression quality due to fatigue. Chest compressions are terminated following return of spontaneous circulation. Unconscious patients with normal breathing are placed in the recovery position. If there is no return of spontaneous circulation, then the decision to terminate chest compressions is based on the clinical judgment that the patient's cardiac arrest is unresponsive to treatment. Finally, it is important that family and patients' loved ones who witness chest compressions be treated with consideration and sensitivity.

  18. Satellite data compression

    CERN Document Server

    Huang, Bormin

    2011-01-01

    Satellite Data Compression covers recent progress in compression techniques for multispectral, hyperspectral and ultra spectral data. A survey of recent advances in the fields of satellite communications, remote sensing and geographical information systems is included. Satellite Data Compression, contributed by leaders in this field, is the first book available on satellite data compression. It covers onboard compression methodology and hardware developments in several space agencies. Case studies are presented on recent advances in satellite data compression techniques via various prediction-

  19. Upconversion chirped pulse amplification of ultrashort pulses using a multimode Tm:ZBLAN fiber

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L.M.; Sosnowski, T.; Stock, M.L.; Norris, T.B.; Squier, J.; Mourou, G. [Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Science; Dennis, M.L.; Duling, I.N. III [Naval Research Lab., Washington, DC (United States)

    1995-11-01

    Microjoule pulse energies are achieved from a single stage upconversion fiber amplifier for the first time in this demonstration of chirped pulse amplification using a multimode TM:ZBLAN fiber. A Ti:sapphire laser system provides the seed pulse for the upconversion fiber amplifier which produces subpicosecond pulse trains with energies as great as 16 {micro}J at repetition rate of 4.4 kHz. The compressed, pulse peak power is more than 1 MW, and the pulse is characterized both temporally and spatially.

  20. t4 Workshop Report*

    Science.gov (United States)

    Kleensang, Andre; Maertens, Alexandra; Rosenberg, Michael; Fitzpatrick, Suzanne; Lamb, Justin; Auerbach, Scott; Brennan, Richard; Crofton, Kevin M.; Gordon, Ben; Fornace, Albert J.; Gaido, Kevin; Gerhold, David; Haw, Robin; Henney, Adriano; Ma’ayan, Avi; McBride, Mary; Monti, Stefano; Ochs, Michael F.; Pandey, Akhilesh; Sharan, Roded; Stierum, Rob; Tugendreich, Stuart; Willett, Catherine; Wittwehr, Clemens; Xia, Jianguo; Patton, Geoffrey W.; Arvidson, Kirk; Bouhifd, Mounir; Hogberg, Helena T.; Luechtefeld, Thomas; Smirnova, Lena; Zhao, Liang; Adeleye, Yeyejide; Kanehisa, Minoru; Carmichael, Paul; Andersen, Melvin E.; Hartung, Thomas

    2014-01-01

    Summary Despite wide-spread consensus on the need to transform toxicology and risk assessment in order to keep pace with technological and computational changes that have revolutionized the life sciences, there remains much work to be done to achieve the vision of toxicology based on a mechanistic foundation. A workshop was organized to explore one key aspect of this transformation – the development of Pathways of Toxicity (PoT) as a key tool for hazard identification based on systems biology. Several issues were discussed in depth in the workshop: The first was the challenge of formally defining the concept of a PoT as distinct from, but complementary to, other toxicological pathway concepts such as mode of action (MoA). The workshop came up with a preliminary definition of PoT as “A molecular definition of cellular processes shown to mediate adverse outcomes of toxicants”. It is further recognized that normal physiological pathways exist that maintain homeostasis and these, sufficiently perturbed, can become PoT. Second, the workshop sought to define the adequate public and commercial resources for PoT information, including data, visualization, analyses, tools, and use-cases, as well as the kinds of efforts that will be necessary to enable the creation of such a resource. Third, the workshop explored ways in which systems biology approaches could inform pathway annotation, and which resources are needed and available that can provide relevant PoT information to the diverse user communities. PMID:24127042

  1. The QED Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, G.W.

    1994-07-01

    On May 18--20, 1994, Argonne National Laboratory hosted the QED Workshop. The workshop was supported by special funding from the Office of Naval Research. The purpose of the workshop was to assemble of a group of researchers to consider whether it is desirable and feasible to build a proof-checked encyclopedia of mathematics, with an associated facility for theorem proving and proof checking. Among the projects represented were Coq, Eves, HOL, ILF, Imps, MathPert, Mizar, NQTHM, NuPrl, OTTER, Proof Pad, Qu-Prolog, and RRL. Although the content of the QED project is highly technical rigorously proof-checked mathematics of all sorts the discussions at the workshop were rarely technical. No prepared talks or papers were given. Instead, the discussions focused primarily on such political, sociological, practical, and aesthetic questions, such as Why do it? Who are the customers? How can one get mathematicians interested? What sort of interfaces are desirable? The most important conclusion of the workshop was that QED is an idea worthy pursuing, a statement with which virtually all the participants agreed. In this document, the authors capture some of the discussions and outline suggestions for the start of a QED scientific community.

  2. Drift compression of an intense neutralized ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Roy, P.K.; Yu, S.S.; Henestroza, E.; Anders, A.; Bieniosek, F.M.; Coleman, J.; Eylon, S.; Greenway, W.G.; Leitner, M.; Logan, B.G.; Waldron, W.L.; Welch, D.R.; Thoma, C.; Sefkow, A.B.; Gilson, E.P.; Efthimion, P.C.; Davidson, R.C.

    2004-10-25

    Longitudinal compression of a tailored-velocity, intense neutralized ion beam has been demonstrated. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. this measurement has been confirmed independently with two different diagnostic systems.

  3. Optimal pseudorandom pulse position modulation ladar waveforms.

    Science.gov (United States)

    Fluckiger, David U; Boland, Brian F; Marcus, Eran

    2015-03-20

    An algorithm for generating optimal pseudorandom pulse position modulation (PRPPM) waveforms for ladar ranging is presented. Bistatic ladar systems using Geiger-mode avalanche photodiodes require detection of several pulses in order to generate sufficient target statistics to satisfy some detection decision rule. For targets with large initial range uncertainty, it becomes convenient to transmit a pulse train with large ambiguity range. One solution is to employ a PRPPM waveform. An optimal PRPPM waveform will have minimal sidelobes: equivalent to 1 or 0 counts after the pulse correlation filter (compression). This can be accomplished by generating PRPPM pulse trains with optimal or minimal sidelobe autocorrelation.

  4. Measurement Control Workshop Instructional Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, Philip [Brookhaven National Lab. (BNL), Upton, NY (United States); Crawford, Cary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGinnis, Brent [Pacific Northwest National Lab. (PNNL), Richland, WA (United States) and Insolves LLC

    2014-04-01

    A workshop to teach the essential elements of an effective nuclear materials control and accountability (MC&A) programs are outlined, along with the modes of Instruction, and the roles and responsibilities of participants in the workshop.

  5. Measurement control workshop instructional materials

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, Philip [Brookhaven National Lab. (BNL), Upton, NY (United States); Crawford, Cary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGinnis, Brent [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Insolves LLC, Piketon, OH (United States)

    2014-04-01

    A workshop to teach the essential elements of an effective nuclear materials control and accountability (MC&A) programs are outlined, along with the modes of Instruction, and the roles and responsibilities of participants in the workshop.

  6. Workshop on moisture buffer capacity

    DEFF Research Database (Denmark)

    2003-01-01

    Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003......Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003...

  7. WALLTURB International Workshop

    CERN Document Server

    Jimenez, Javier; Marusic, Ivan

    2011-01-01

    This book brings together selected contributions from the WALLTURB workshop on ”Understanding and modelling of wall turbulence” held in Lille, France, on April 21st to 23rd 2009. This workshop was organized by the WALLTURB consortium, in order to present to the relevant scientific community the main results of the project and to stimulate scientific discussions around the subject of wall turbulence. The workshop reviewed the recent progress in theoretical, experimental and numerical approaches to wall turbulence. The problems of zero pressure gradient, adverse pressure gradient and separating turbulent boundary layers were addressed in detail with the three approaches, using the most advanced tools. This book is a milestone in the research field, thanks to the high level of the invited speakers and the involvement of the contributors and a testimony of the achievement of the WALLTURB project.

  8. Chromosome 19 International Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Pericak-Vance, M.A. (Duke Univ., Durham, NC (United States). Medical Center); Ropers, H.H. (Univ. Hospital Nijmegen, (The Netherlands). Dept. of Human Genetics); Carrano, A.J. (Lawrence Livermore National Lab., CA (United States))

    1993-01-04

    The Second International Workshop on Human Chromosome 19 was hosted on January 25 and 26, 1992, by the Department of Human Genetics, University Hospital Nijmegen, The Netherlands, at the 'Meerdal Conference Center'. The workshop was supported by a grant from the European Community obtained through HUGO, the Dutch Research Organization (NWO) and the Muscular Dystrophy Association (MDA). Travel support for American participants was provided by the Department of Energy. The goals of this workshop were to produce genetic, physical and integrated maps of chromosome 19, to identify inconsistencies and gaps, and to discuss and exchange resources and techniques available for the completion of these maps. The second day of the meeting was largely devoted to region or disease specific efforts. In particular, the meeting served as a platform for assessing and discussing the recent progress made into the molecular elucidation of myotonic dystrophy.

  9. Workshop on molecular animation.

    Science.gov (United States)

    Bromberg, Sarina; Chiu, Wah; Ferrin, Thomas E

    2010-10-13

    From February 25 to 26, 2010, in San Francisco, the Resource for Biocomputing, Visualization, and Informatics (RBVI) and the National Center for Macromolecular Imaging (NCMI) hosted a molecular animation workshop for 21 structural biologists, molecular animators, and creators of molecular visualization software. Molecular animation aims to visualize scientific understanding of biomolecular processes and structures. The primary goal of the workshop was to identify the necessary tools for producing high-quality molecular animations, understanding complex molecular and cellular structures, creating publication supplementary materials and conference presentations, and teaching science to students and the public. Another use of molecular animation emerged in the workshop: helping to focus scientific inquiry about the motions of molecules and enhancing informal communication within and between laboratories.

  10. African Otter Workshop

    Directory of Open Access Journals (Sweden)

    Jan Reed-Smith

    2016-04-01

    Full Text Available All concerned thought this was an excellent workshop with important progress made towards creating a viable beginning of an African Otter Network. There is a long road ahead but the 2015 African Otter Workshop is a start on developing range country partners, activists and researchers as well as collaborating on issue identification and resolution which will assist in preserving at least some refugia for Africa’s otters. A list of actions was agreed on, including the creation of an African Otter Network website and social media network, apublic Otter Awareness facebook page, encouraging online reporting of otter sightings, conducting otter awareness surveys, and emphasising the need for communication with the public, other members of the network and other professionals. information not shared or documented is information LOST. A Second African Otter Workshop should be held in 2017 elsewhere in Africa to encourage attendance from a wider range of countries.

  11. QCD Evolution Workshop

    CERN Document Server

    2015-01-01

    These are the proceedings of the QCD Evolution 2015 Workshop which was held 26–30 May, 2015 at Jefferson Lab, Newport News, Virginia, USA. The workshop is a continuation of a series of workshops held during four consecutive years 2011, 2012, 2013 at Jefferson Lab, and in 2014 in Santa Fe, NM. With the rapid developments in our understanding of the evolution of parton distributions including low-x, TMDs, GPDs, higher-twist correlation functions, and the associated progress in perturbative QCD, lattice QCD and effective field theory techniques we look forward with great enthusiasm to the 2015 meeting. A special attention was also paid to participation of experimentalists as the topics discussed are of immediate importance for the JLab 12 experimental program and a future Electron Ion Collider.

  12. Vulcano Workshop 2016

    CERN Document Server

    2016-01-01

    We announce the XVI Vulcano Workshop, which will be held from May 22nd to May 28th, 2016 in the Vulcano Island (Sicily, Italy). As in the past editions, the workshop will aim to gather people from High Energy Astrophysics and Particle Physics to discuss the most recent highlights in these fields. The workshop will cover the following topics: Astrophysics/Cosmology, Astrophysics/Gravity, Dark Matter, Particle Physics, Cosmic Rays, Gamma/Neutrino Astronomy, Neutrinos and Future Prospects. The scientific program will include several 30-minute review talks, to introduce the current problems, and 20-minute talks, giving new experimental and theoretical results. The participation is by invitation and limited to 80 people.

  13. Effects of manual chest compression and descompression maneuver on lung volumes, capnography and pulse oximetry in patients receiving mechanical ventilation Efeitos da manobra de compressão e descompressão torácica nos volumes pulmonares, capnografia e oximetria de pulso em pacientes submetidos à ventilação mecânica

    Directory of Open Access Journals (Sweden)

    Fabiana Della Via

    2012-10-01

    Full Text Available OBJECTIVES: The aims of this study were to evaluate whether there are changes in lung volumes, capnography, pulse oximetry and hemodynamic parameters associated with manual chest compression-decompression maneuver (MCCD in patients undergoing mechanical ventilation (MV. Method: A prospective study of 65 patients undergoing to MV after 24 hours. All patients received bronchial hygiene maneuvers and after 30 minutes they were submitted to ten repetitions of the MCCD during 10 consecutive respiratory cycles in the right hemithorax and than in the left hemithorax. The data were collected before the application of the maneuver and after 1, 5, 10, 15, 20, 25, 30, 35 and 40 minutes following application of the maneuver. RESULTS: There were statistical significant (pOBJETIVOS: Avaliar a presença de alterações nos volumes pulmonares, oximetria de pulso, capnografia e alterações hemodinâmicas associadas à intervenção da manobra de compressão e descompressão torácica (MCDT nos pacientes submetidos à ventilação mecânica (VM. Método: Tratou-se de um estudo prospectivo em que foram incluídos 65 pacientes em VM há mais de 24 horas. O protocolo consistiu na aplicação de manobras de higiene brônquica e, após 30 minutos, os pacientes eram submetidos a dez repetições da MCDT em dez respirações consecutivas no hemitórax direito e, posteriormente, no hemitórax esquerdo, coletando os dados antes e após a aplicação da manobra nos tempos 1, 5, 10, 15, 20, 25, 30, 35 e 40 minutos. RESULTADOS: Constatou-se aumento significante (p<0,001 do volume corrente inspiratório (pré: 458,2±132,1 ml; pós 1 minuto: 557,3±139,1; pós 40 minutos: 574,4±151, volume minuto corrente (pré: 7,0±2,7 L/min; pós 1 minuto: 8,7±3,3; pós 40 minutos: 8,8±3,8 e oximetria de pulso (pré: 97,4±2,2%; pós 1 minuto: 97,9±1,8; pós 40 minutos: 98,2±1,6; p<0,05. Ocorreu redução no CO2 expirado (pré: 35,1±9,0 mmHg; pós 1 minuto: 31,5±8,2; pós 40

  14. NX15 science workshop

    CERN Multimedia

    2015-01-01

    Science. For some of us, it's daunting or maybe even terrifying. How to tell a good science story? That's the question we will explore together in this workshop. Conceived and produced by journalist and Scientific News producer Claudio Rosmino of Euronews, and presented by Euronews' Jeremy Wilks, the workshop will look at actual case studies (from Euronews and beyond) where science news proved exciting, inspiring and accessible to audiences around the world. These might include the Rosetta mission and CERN's work on Science for Peace. Together, we'll share ideas and knowledge around how science journalism and science news can increase its visibility in the media and maybe save the planet...!

  15. 2015 Workshop on Continuations

    DEFF Research Database (Denmark)

    his volume contains the papers presented at WoC 2015, the Workshop on Continuations held at ETAPS 2015. There were four submissions. Each of them was reviewed by, on the average, three PC members. The committee decided to accept three papers. The program also includes one invited talk. It also...... documents the depth, variety, and richness of continuations with four distilled tutorials. Thanks are due to the local organizers of ETAPS 2015 for the infras- tructure and to the general chairman of WoC 2015, Ugo de'Liguoro, for initiating this workshop and making it happen...

  16. Magnetized Plasma Compression for Fusion Energy

    Science.gov (United States)

    Degnan, James; Grabowski, Christopher; Domonkos, Matthew; Amdahl, David

    2013-10-01

    Magnetized Plasma Compression (MPC) uses magnetic inhibition of thermal conduction and enhancement of charge particle product capture to greatly reduce the temporal and spatial compression required relative to un-magnetized inertial fusion (IFE)--to microseconds, centimeters vs nanoseconds, sub-millimeter. MPC greatly reduces the required confinement time relative to MFE--to microseconds vs minutes. Proof of principle can be demonstrated or refuted using high current pulsed power driven compression of magnetized plasmas using magnetic pressure driven implosions of metal shells, known as imploding liners. This can be done at a cost of a few tens of millions of dollars. If demonstrated, it becomes worthwhile to develop repetitive implosion drivers. One approach is to use arrays of heavy ion beams for energy production, though with much less temporal and spatial compression than that envisioned for un-magnetized IFE, with larger compression targets, and with much less ambitious compression ratios. A less expensive, repetitive pulsed power driver, if feasible, would require engineering development for transient, rapidly replaceable transmission lines such as envisioned by Sandia National Laboratories. Supported by DOE-OFES.

  17. Workshops as a Research Methodology

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Levinsen, Karin Tweddell

    2017-01-01

    This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice, and worksh......This paper contributes to knowledge on workshops as a research methodology, and specifically on how such workshops pertain to e-learning. A literature review illustrated that workshops are discussed according to three different perspectives: workshops as a means, workshops as practice......, and workshops as a research methodology. Focusing primarily on the latter, this paper presents five studies on upper secondary and higher education teachers’ professional development and on teaching and learning through video conferencing. Through analysis and discussion of these studies’ findings, we argue...... that workshops provide a platform that can aid researchers in identifying and exploring relevant factors in a given domain by providing means for understanding complex work and knowledge processes that are supported by technology (for example, e-learning). The approach supports identifying factors...

  18. Report of the Orientation Workshop

    DEFF Research Database (Denmark)

    Nunez, Heilyn Camacho; Buus, Lillian; Ogange, Betty

    2014-01-01

    This Orientation Workshops is part of MAAGART project. The workshop is divided in three parts: 1) pre-Orientation Workshop stage, 2) Face-to-Face stage and 3) post-Orientation stage. Pre and post stages will be developed online. All the activities will take place in a virtual learning environment...... the third stage....

  19. Contributions to the 4. reflectometry workshop

    Energy Technology Data Exchange (ETDEWEB)

    Clairet, F

    1999-09-15

    This document contains ten papers presented during the 4. workshop on reflectometry. Those papers deal with the utility of reflectometry to plasma density fluctuations study or reflectometry based plasma diagnostics: X mode reflectometry on edge density profile measurements on Tore Supra; recent results of reflectometry on ASDEX-UPGRADE; automatic evaluation of density profiles with high temporal resolution; the TJ-II reflectometry system; doppler reflectometry for the investigation of poloidally propagating density perturbations; poloidal rotation measuremin Tore Supra by oblique reflectometry; pulsed radar reflectometry at TEXTOR-94; density profile reconstruction methods using dispersive effects in pulse radar reflectometry; fluctuation reflectometry: two dimensional full wave modelling; phase ramping and modulation of reflectometer signals. (A.L.B.)

  20. Second Quaternary dating workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The second Quaternary dating methods workshop was held at Lucas Heights and sponsored by ANSTO and AINSE. Topics covered include, isotope and thermoluminescence dating, usage of accelerator and thermal ionisation mass spectrometry in environmental studies emphasizing on the methodologies used and sample preparation

  1. Flywheel energy storage workshop

    Energy Technology Data Exchange (ETDEWEB)

    O`Kain, D.; Carmack, J. [comps.

    1995-12-31

    Since the November 1993 Flywheel Workshop, there has been a major surge of interest in Flywheel Energy Storage. Numerous flywheel programs have been funded by the Advanced Research Projects Agency (ARPA), by the Department of Energy (DOE) through the Hybrid Vehicle Program, and by private investment. Several new prototype systems have been built and are being tested. The operational performance characteristics of flywheel energy storage are being recognized as attractive for a number of potential applications. Programs are underway to develop flywheels for cars, buses, boats, trains, satellites, and for electric utility applications such as power quality, uninterruptible power supplies, and load leveling. With the tremendous amount of flywheel activity during the last two years, this workshop should again provide an excellent opportunity for presentation of new information. This workshop is jointly sponsored by ARPA and DOE to provide a review of the status of current flywheel programs and to provide a forum for presentation of new flywheel technology. Technology areas of interest include flywheel applications, flywheel systems, design, materials, fabrication, assembly, safety & containment, ball bearings, magnetic bearings, motor/generators, power electronics, mounting systems, test procedures, and systems integration. Information from the workshop will help guide ARPA & DOE planning for future flywheel programs. This document is comprised of detailed viewgraphs.

  2. FINPIE/97. Workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This publication contains the proceedings of 1997 Finnish Workshop on Power and Industrial Electronics, held in Espoo, Finland, on 26 August, 1997. The programme consisted of technical sessions on Advanced AC Motor Control, Electric Machines and Drives, Advanced Control and Measurement, Power Electronics Systems, Modelling and Simulation, and Power Converters

  3. International phosphorus workshop

    DEFF Research Database (Denmark)

    Kronvang, Brian; Rubæk, Gitte Holton; Heckrath, Goswin

    2009-01-01

    the main outcomes of the workshop and the special collection of eight papers. Moreover, we identify the main gaps in our knowledge and future research directions on P, which are linked to important issues such as addressing scale effects, improved P models with the ability to quantify uncertainty...

  4. Workshop on Mathematical Physics

    CERN Document Server

    2016-01-01

    This two-day workshop will include seminars by mathematicians and physicists on topics of mutual interest. It will precede the 31st International Colloquium on Group Theoretical Methods in Physics which will be held in Rio de Janeiro from June 19-25.

  5. Workshop on hybrid rice

    Institute of Scientific and Technical Information of China (English)

    TANZhijun

    1994-01-01

    FAO, in collaboration with FEDEARROZ in Colombia and EMBRAPA / CNPAF in Brail, organized a workshop on the Establishment of a Coorperative Research Network on Hybrid Rice in Latin America and the Caribbean held from Mar 16 to 18, 1994 at EMBRAPA/CNPAF in Brazil. Dr MAO Changxiang,

  6. Workshop on Molecular Evolution

    Science.gov (United States)

    Cummings, Michael P.

    2004-01-01

    Molecular evolution has become the nexus of many areas of biological research. It both brings together and enriches such areas as biochemistry, molecular biology, microbiology, population genetics, systematics, developmental biology, genomics, bioinformatics, in vitro evolution, and molecular ecology. The Workshop provides an important contribution to these fields in that it promotes interdisciplinary research and interaction, and thus provides a glue that sticks together disparate fields. Due to the wide range of fields addressed by the study of molecular evolution, it is difficult to offer a comprehensive course in a university setting. It is rare for a single institution to maintain expertise in all necessary areas. In contrast, the Workshop is uniquely able to provide necessary breadth and depth by utilizing a large number of faculty with appropriate expertise. Furthermore, the flexible nature of the Workshop allows for rapid adaptation to changes in the dynamic field of molecular evolution. For example, the 2003 Workshop included recently emergent research areas of molecular evolution of development and genomics.

  7. Summary of cosmology workshop

    Indian Academy of Sciences (India)

    Tarun Sandeep

    2004-10-01

    Cosmology is passing through a golden phase of rapid advance. The cosmology workshop at ICGC-2004 attracted a large number of research contributions to diverse topics of cosmology. I attempt to classify and summarize the research work and results of the oral and poster presentations made at the meeting.

  8. Dynamic defense workshop :

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, Sean Michael; Doak, Justin E.; Haas, Jason Juedes.; Helinski, Ryan; Lamb, Christopher C.

    2013-02-01

    On September 5th and 6th, 2012, the Dynamic Defense Workshop: From Research to Practice brought together researchers from academia, industry, and Sandia with the goals of increasing collaboration between Sandia National Laboratories and external organizations, de ning and un- derstanding dynamic, or moving target, defense concepts and directions, and gaining a greater understanding of the state of the art for dynamic defense. Through the workshop, we broadened and re ned our de nition and understanding, identi ed new approaches to inherent challenges, and de ned principles of dynamic defense. Half of the workshop was devoted to presentations of current state-of-the-art work. Presentation topics included areas such as the failure of current defenses, threats, techniques, goals of dynamic defense, theory, foundations of dynamic defense, future directions and open research questions related to dynamic defense. The remainder of the workshop was discussion, which was broken down into sessions on de ning challenges, applications to host or mobile environments, applications to enterprise network environments, exploring research and operational taxonomies, and determining how to apply scienti c rigor to and investigating the eld of dynamic defense.

  9. Workshop on DNA repair.

    NARCIS (Netherlands)

    A.R. Lehmann (Alan); J.H.J. Hoeijmakers (Jan); A.A. van Zeeland (Albert); C.M.P. Backendorf (Claude); B.A. Bridges; A. Collins; R.P.D. Fuchs; G.P. Margison; R. Montesano; E. Moustacchi; A.T. Natarajan; M. Radman; A. Sarasin; E. Seeberg; C.A. Smith; M. Stefanini (Miria); L.H. Thompson; G.P. van der Schans; C.A. Weber (Christine); M.Z. Zdzienika

    1992-01-01

    textabstractA workshop on DNA repair with emphasis on eukaryotic systems was held, under the auspices of the EC Concerted Action on DNA Repair and Cancer, at Noordwijkerhout (The Netherlands) 14-19 April 1991. The local organization of the meeting was done under the auspices of the Medical Genetic C

  10. Beginnings Workshop: Mealtimes.

    Science.gov (United States)

    Gordon, Sarah A. Mulligan; And Others

    1997-01-01

    Contains four workshop presentations on meals in child care: (1) "Enjoying Family-Style Meals in Child Care" (Sarah A. Mulligan Gordon); (2) "The Making of a Healthy Eater: Winning the Finicky Eater Battle" (James M. Thomas and others); (3) "Food for Thought: Mealtimes can be Educational and Enjoyable, Too" (Karen…

  11. Radiation Source Replacement Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.

    2010-12-01

    This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.

  12. Workshop One : Risk Analysis

    NARCIS (Netherlands)

    Carlson, T.J.; Jong, C.A.F. de; Dekeling, R.P.A.

    2012-01-01

    The workshop looked at the assessment of risk to aquatic animals exposed to anthropogenic sound. The discussion focused on marine mammals given the worldwide attention being paid to them at the present time, particularly in relationship to oil and gas exploration, ocean power, and increases in ship

  13. ATLAS TRT 2002 Workshop

    CERN Multimedia

    Capeans, M.

    Starting on 17th May, the ATLAS TRT 2002 Workshop was organised by Ken MacFarlane and his team at Hampton University, Virginia, USA. During a welcome break in the very dense workshop programme, the group enjoyed a half-day long boat trip along the waterways, offering a first-hand look at the history and heritage of this part of America. The attendance during the six-day workshop was about 50 people representing most of the collaborating institutes, although many Russian colleagues had stayed in their institutes to pursue the start-up of end-cap wheel production at PNPI and DUBNA. The meeting clearly showed that, during the year 2002, the TRT community is focusing on final design issues and module/wheel construction, while moving at the same time towards acceptance testing and integration, including the front-end electronics. The two main topics treated at the workshop were the preparation for beginning full production of the FE electronics, and the wire-joint problem that the US barrel colleagues have been fa...

  14. Pulse width tunable subpicosecond pulse generation from an actively modelocked monolithic MQW laser/MQW electroabsorption modulator

    Science.gov (United States)

    Takada, A.; Sato, K.; Saruwatari, M.; Yamamoto, M.

    1994-05-01

    Actively modelocked pulses are generated from a 1.59 micron MQW laser integrated with an MQW electroabsorption modulator driven at the monolithic cavity frequency. The pulse width is controlled from 39 ps to 0.55 ps by changing the inverse bias voltage applied to the electroabsorption modulator and by linear pulse compression using a fiber.

  15. Flywheel Energy Storage technology workshop

    Energy Technology Data Exchange (ETDEWEB)

    O`Kain, D.; Howell, D. [comps.

    1993-12-31

    Advances in recent years of high strength/lightweight materials, high performance magnetic bearings, and power electronics technology has spurred a renewed interest by the transportation, utility, and manufacturing industries in Flywheel Energy Storage (FES) technologies. FES offers several advantages over conventional electro-chemical energy storage, such as high specific energy and specific power, fast charging time, long service life, high turnaround efficiency (energy out/energy in), and no hazardous/toxic materials or chemicals are involved. Potential applications of FES units include power supplies for hybrid and electric vehicles, electric vehicle charging stations, space systems, and pulsed power devices. Also, FES units can be used for utility load leveling, uninterruptable power supplies to protect electronic equipment and electrical machinery, and for intermittent wind or photovoltaic energy sources. The purpose of this workshop is to provide a forum to highlight technologies that offer a high potential to increase the performance of FES systems and to discuss potential solutions to overcome present FES application barriers. This document consists of viewgraphs from 27 presentations.

  16. UVI Cyber-security Workshop Workshop Analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Kuykendall, Tommie G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Allsop, Jacob Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, Benjamin Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Boumedine, Marc [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carter, Cedric [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Galvin, Seanmichael Yurko [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Oscar [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Wellington K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lin, Han Wei [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Morris, Tyler Jake [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nauer, Kevin S.; Potts, Beth A.; Ta, Kim Thanh; Trasti, Jennifer; White, David R.

    2015-07-08

    The cybersecurity consortium, which was established by DOE/NNSA’s Minority Serving Institutions Partnerships Program (MSIPP), allows students from any of the partner schools (13 HBCUs, two national laboratories, and a public school district) to have all consortia options available to them, to create career paths and to open doors to DOE sites and facilities to student members of the consortium. As a part of this year consortium activities, Sandia National Laboratories and the University of Virgin Islands conducted a week long cyber workshop that consisted of three courses; Digital Forensics and Malware Analysis, Python Programming, and ThunderBird Cup. These courses are designed to enhance cyber defense skills and promote learning within STEM related fields.

  17. Dynamic characterization and amplification of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard

    2013-01-01

    We show a first-time demonstration of amplification of 400 fs pulses in a fiber optical parametric amplifier. The 400 fs signal is stretched in time, amplified by 26 dB and compressed back to 500 fs. A significant broadening of the pulses is experimentally shown due to dispersion and limited gain...

  18. Micro pulse laser radar

    Science.gov (United States)

    Spinhirne, James D. (Inventor)

    1993-01-01

    An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

  19. High gain broadband amplification of ultraviolet pulses in optical parametric chirped pulse amplifier.

    Science.gov (United States)

    Wnuk, Paweł; Stepanenko, Yuriy; Radzewicz, Czesław

    2010-04-12

    We report on a high gain amplification of broadband ultraviolet femtosecond pulses in an optical parametric chirped pulse amplifier. Broadband ultraviolet seed pulses were obtained by an achromatic frequency doubling of the output from a femtosecond Ti:Sapphire oscillator. Stretched seed pulses were amplified in a multipass parametric amplifier with a single BBO crystal pumped by a ns frequency quadrupled Nd:YAG laser. A noncollinear configuration was used for a broadband amplification. The total (after compression) amplification of 2.510(5) was achieved, with compressed pulse energy of 30 microJ and pulse duration of 24 fs. We found that the measured gain was limited by thermal effects induced by the absorption of the pump laser by color centers created in the BBO crystal.

  20. Lossless compression of medical images using Hilbert scan

    Science.gov (United States)

    Sun, Ziguang; Li, Chungui; Liu, Hao; Zhang, Zengfang

    2007-12-01

    The effectiveness of Hilbert scan in lossless medical images compression is discussed. In our methods, after coding of intensities, the pixels in a medical images have been decorrelated with differential pulse code modulation, then the error image has been rearranged using Hilbert scan, finally we implement five coding schemes, such as Huffman coding, RLE, lZW coding, Arithmetic coding, and RLE followed by Huffman coding. The experiments show that the case, which applies DPCM followed by Hilbert scan and then compressed by the Arithmetic coding scheme, has the best compression result, also indicate that Hilbert scan can enhance pixel locality, and increase the compression ratio effectively.

  1. Generation And Measurement Of High Contrast Ultrashort Intense Laser Pulses

    CERN Document Server

    Konoplev, O A

    2000-01-01

    In this thesis, the generation and measurement of high contrast, intense, ultrashort pulses have been studied. Various factors affecting the contrast and pulse shape of ultrashort light pulses from a chirped pulse amplification (CPA) laser system are identified. The level of contrast resulting from influence of these factors is estimated. Methods for improving and controlling the pulse shape and increasing the contrast are discussed. Ultrahigh contrast, 1-ps pulses were generated from a CPA system with no temporal structure up to eleven orders of magnitude. This is eight orders of magnitude higher contrast than the original pulse. This contrast boost was achieved using two techniques. One is the optical pulse cleaning based on the nonlinear birefringence of the chirping fiber and applied to the pulses before amplification. The other is the fast saturable absorber. The fast saturable absorber was placed after amplification and compression of the pulse. The measurements of high-contrast, ultrashort pulse with h...

  2. 90 mJ parametric chirped pulse amplification of 10 fs pulses.

    Science.gov (United States)

    Tavella, Franz; Marcinkevicius, Andrius; Krausz, Ferenc

    2006-12-25

    We demonstrate the amplification of broadband pulses from a Ti:Sapphire oscillator by non-collinear optical parametric chirped-pulse amplification technique in a type-I BBO crystal to energies of 90 mJ. Partial compression of the amplified pulses is demonstrated down to a 10 fs duration. These parameters come in combination with good spatial quality and focusability of the amplified beam.

  3. Accelerator reliability workshop

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, L.; Duru, Ph.; Koch, J.M.; Revol, J.L.; Van Vaerenbergh, P.; Volpe, A.M.; Clugnet, K.; Dely, A.; Goodhew, D

    2002-07-01

    About 80 experts attended this workshop, which brought together all accelerator communities: accelerator driven systems, X-ray sources, medical and industrial accelerators, spallation sources projects (American and European), nuclear physics, etc. With newly proposed accelerator applications such as nuclear waste transmutation, replacement of nuclear power plants and others. Reliability has now become a number one priority for accelerator designers. Every part of an accelerator facility from cryogenic systems to data storage via RF systems are concerned by reliability. This aspect is now taken into account in the design/budget phase, especially for projects whose goal is to reach no more than 10 interruptions per year. This document gathers the slides but not the proceedings of the workshop.

  4. Spiral 2 workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop.

  5. PREFACE: Collapse Calderas Workshop

    Science.gov (United States)

    Gottsmann, Jo; Aguirre-Diaz, Gerardo

    2008-10-01

    Caldera-formation is one of the most awe-inspiring and powerful displays of nature's force. Resultant deposits may cover vast areas and significantly alter the immediate topography. Post-collapse activity may include resurgence, unrest, intra-caldera volcanism and potentially the start of a new magmatic cycle, perhaps eventually leading to renewed collapse. Since volcanoes and their eruptions are the surface manifestation of magmatic processes, calderas provide key insights into the generation and evolution of large-volume silicic magma bodies in the Earth's crust. Despite their potentially ferocious nature, calderas play a crucial role in modern society's life. Collapse calderas host essential economic deposits and supply power for many via the exploitation of geothermal reservoirs, and thus receive considerable scientific, economic and industrial attention. Calderas also attract millions of visitors world-wide with their spectacular scenic displays. To build on the outcomes of the 2005 calderas workshop in Tenerife (Spain) and to assess the most recent advances on caldera research, a follow-up meeting was proposed to be held in Mexico in 2008. This abstract volume presents contributions to the 2nd Calderas Workshop held at Hotel Misión La Muralla, Querétaro, Mexico, 19-25 October 2008. The title of the workshop `Reconstructing the evolution of collapse calderas: Magma storage, mobilisation and eruption' set the theme for five days of presentations and discussions, both at the venue as well as during visits to the surrounding calderas of Amealco, Amazcala and Huichapan. The multi-disciplinary workshop was attended by more than 40 scientist from North, Central and South America, Europe, Australia and Asia. Contributions covered five thematic topics: geology, geochemistry/petrology, structural analysis/modelling, geophysics, and hazards. The workshop was generously supported by the International Association of Volcanology and the Chemistry of The Earth's Interior

  6. Solar workshops financial incentives

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-01-01

    Ten one-day workshops were held across the United States. Information in this workbook is compiled in conjunction with those workshops. The following discussions are included: solar as a fuel (history); why alternative fuels are being sought today; the need for conservation; advantages of solar energy; the potential of solar energy; why solar energy is not more widely used; a definition of solar; how solar can help meet energy demands; Federal policies and programs; what solar technologies exist today that can be effectively utilized (thermal applications, fuels from biomass, solar electric). Additional information is presented in three attachments: Energy-Conserving Methods; Domestic Policy Review of Solar Energy; and DOE Secretary's Annual Report to Congress-Solar Section. (MCW)

  7. Imaging Sciences Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Candy, J.V.

    1996-11-21

    This report contains the proceedings of the Imaging Sciences Workshop sponsored by C.A.S.LS., the Center for Advanced Signal & Image Sciences. The Center, established primarily to provide a forum where researchers can freely exchange ideas on the signal and image sciences in a comfortable intellectual environment, has grown over the last two years with the opening of a Reference Library (located in Building 272). The Technical Program for the 1996 Workshop include a variety of efforts in the Imaging Sciences including applications in the Microwave Imaging, highlighted by the Micro-Impulse Radar (MIR) system invented at LLNL, as well as other applications in this area. Special sessions organized by various individuals in Speech, Acoustic Ocean Imaging, Radar Ocean Imaging, Ultrasonic Imaging, and Optical Imaging discuss various applica- tions of real world problems. For the more theoretical, sessions on Imaging Algorithms and Computed Tomography were organized as well as for the more pragmatic featuring a session on Imaging Systems.

  8. Imaging sciences workshop

    Energy Technology Data Exchange (ETDEWEB)

    Candy, J.V.

    1994-11-15

    This workshop on the Imaging Sciences sponsored by Lawrence Livermore National Laboratory contains short abstracts/articles submitted by speakers. The topic areas covered include the following: Astronomical Imaging; biomedical imaging; vision/image display; imaging hardware; imaging software; Acoustic/oceanic imaging; microwave/acoustic imaging; computed tomography; physical imaging; imaging algorithms. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  9. Aims of the Workshop

    CERN Document Server

    Dornan, P J

    2010-01-01

    There are challenges and opportunities for the European particle physics community to engage with innovative and exciting developments which could lead to precision measurements in the neutrino sector. These have the potential to yield significant advances in the understanding of CP violation, the flavour riddle and theories beyond the Standard Model. This workshop aims to start the process of a dialogue in Europe so that informed decisions on the appropriate directions to pursue can be made in a few years time.

  10. The ROS Workshop

    CERN Multimedia

    Francis, D.

    The first week of February saw the taking place of the ReadOut Subsystem (ROS) workshop. The ROS is the subsystem of the Trigger, DAQ & DCS project which receives and buffers data from the detector ReadOut Drivers (RODs). On request it then provides a subset of this buffered data, the so-called Regions of Interest (RoI), to the Level 2 trigger. Using the subsequent Level 2 trigger decision, the ROS either removes the buffered event data from its buffers or sends the full event data to the Event Filter for further processing. The workshop took place over a four-day period at a location in the Jura. The average daily attendance was twenty people, which mainly represented the five main ATLAS institutes currently engaged in this Trigger, DAQ & DCS activity. The aim of the workshop was to bring to an end the current prototyping activities in this area and launch the next, final, phase of prototyping. This new phase of prototyping will build on the successful activities of the previous phase and will focus...

  11. Grid and Entrepreneurship Workshop

    CERN Multimedia

    2006-01-01

    The CERN openlab is organising a special workshop about Grid opportunities for entrepreneurship. This one-day event will provide an overview of what is involved in spin-off technology, with a special reference to the context of computing and data Grids. Lectures by experienced entrepreneurs will introduce the key concepts of entrepreneurship and review, in particular, the industrial potential of EGEE (the EU co-funded Enabling Grids for E-sciencE project, led by CERN). Case studies will be given by CEOs of European start-ups already active in the Grid and computing cluster area, and regional experts will provide an overview of efforts in several European regions to stimulate entrepreneurship. This workshop is designed to encourage students and researchers involved or interested in Grid technology to consider the entrepreneurial opportunities that this technology may create in the coming years. This workshop is organized as part of the CERN openlab student programme, which is co-sponsored by CERN, HP, ...

  12. Magnetic Flux Compression in Plasmas

    Science.gov (United States)

    Velikovich, A. L.

    2012-10-01

    Magnetic flux compression (MFC) as a method for producing ultra-high pulsed magnetic fields had been originated in the 1950s by Sakharov et al. at Arzamas in the USSR (now VNIIEF, Russia) and by Fowler et al. at Los Alamos in the US. The highest magnetic field produced by explosively driven MFC generator, 28 MG, was reported by Boyko et al. of VNIIEF. The idea of using MFC to increase the magnetic field in a magnetically confined plasma to 3-10 MG, relaxing the strict requirements on the plasma density and Lawson time, gave rise to the research area known as MTF in the US and MAGO in Russia. To make a difference in ICF, a magnetic field of ˜100 MG should be generated via MFC by a plasma liner as a part of the capsule compression scenario on a laser or pulsed power facility. This approach was first suggested in mid-1980s by Liberman and Velikovich in the USSR and Felber in the US. It has not been obvious from the start that it could work at all, given that so many mechanisms exist for anomalously fast penetration of magnetic field through plasma. And yet, many experiments stimulated by this proposal since 1986, mostly using pulsed-power drivers, demonstrated reasonably good flux compression up to ˜42 MG, although diagnostics of magnetic fields of such magnitude in HED plasmas is still problematic. The new interest of MFC in plasmas emerged with the advancement of new drivers, diagnostic methods and simulation tools. Experiments on MFC in a deuterium plasma filling a cylindrical plastic liner imploded by OMEGA laser beam led by Knauer, Betti et al. at LLE produced peak fields of 36 MG. The novel MagLIF approach to low-cost, high-efficiency ICF pursued by Herrmann, Slutz, Vesey et al. at Sandia involves pulsed-power-driven MFC to a peak field of ˜130 MG in a DT plasma. A review of the progress, current status and future prospects of MFC in plasmas is presented.

  13. Workshop on extremely high energy density plasmas and their diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Shozo (ed.)

    2001-09-01

    Compiled are the papers presented at the workshop on 'Extremely High Energy Density Plasmas and Their Diagnostics' held at National Institute for Fusion Science. The papers cover physics and applications of extremely high-energy density plasmas such as dense z-pinch, plasma focus, and intense pulsed charged beams. Separate abstracts were presented for 7 of the papers in this report. The remaining 25 were considered outside the subject scope of INIS. (author)

  14. Focus on Compression Stockings

    Science.gov (United States)

    ... the stocking every other day with a mild soap. Do not use Woolite™ detergent. Use warm water ... compression clothing will lose its elasticity and its effectiveness. Compression stockings last for about 4-6 months ...

  15. A Compressive Superresolution Display

    KAUST Repository

    Heide, Felix

    2014-06-22

    In this paper, we introduce a new compressive display architecture for superresolution image presentation that exploits co-design of the optical device configuration and compressive computation. Our display allows for superresolution, HDR, or glasses-free 3D presentation.

  16. 2014 Penn State Bioinorganic Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Golbeck, John [Pennsylvania State Univ., State College, PA (United States)

    2015-10-01

    The 3rd Penn State Bioinorganic Workshop took place in early June 2014 and was combined with the 3rd Penn State Frontiers in Metallobiochemistry Symposium. The workshop was even larger than the 2nd Penn State Bioinorganic Workshop we offered in 2012. It had even more participants (162 rather than 123 in 2012). Like the 2012 workshop, the 2014 workshop had three parts. The first part consisted of 16 90-minute lectures presented by faculty experts on the topic of their expertise (see below). Based on the suggestions from the 2012 workshop, we have recorded all 16 lectures professionally and make them available to the entire bioinorganic community via online streaming. In addition, hard copies of the recordings are available as backup.

  17. Microbunching and RF Compression

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-05-23

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  18. Hyperspectral data compression

    CERN Document Server

    Motta, Giovanni; Storer, James A

    2006-01-01

    Provides a survey of results in the field of compression of remote sensed 3D data, with a particular interest in hyperspectral imagery. This work covers topics such as compression architecture, lossless compression, lossy techniques, and more. It also describes a lossless algorithm based on vector quantization.

  19. Compressed gas manifold

    Science.gov (United States)

    Hildebrand, Richard J.; Wozniak, John J.

    2001-01-01

    A compressed gas storage cell interconnecting manifold including a thermally activated pressure relief device, a manual safety shut-off valve, and a port for connecting the compressed gas storage cells to a motor vehicle power source and to a refueling adapter. The manifold is mechanically and pneumatically connected to a compressed gas storage cell by a bolt including a gas passage therein.

  20. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Hansen, Esben Rune; Satti, Srinivasa Rao; Tiedemann, Peter

    2008-01-01

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  1. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Rune Hansen, Esben; Srinivasa Rao, S.; Tiedemann, Peter

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  2. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Hansen, Esben Rune; Satti, Srinivasa Rao; Tiedemann, Peter

    2008-01-01

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  3. Optical Network Testbeds Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Joe Mambretti

    2007-06-01

    This is the summary report of the third annual Optical Networking Testbed Workshop (ONT3), which brought together leading members of the international advanced research community to address major challenges in creating next generation communication services and technologies. Networking research and development (R&D) communities throughout the world continue to discover new methods and technologies that are enabling breakthroughs in advanced communications. These discoveries are keystones for building the foundation of the future economy, which requires the sophisticated management of extremely large qualities of digital information through high performance communications. This innovation is made possible by basic research and experiments within laboratories and on specialized testbeds. Initial network research and development initiatives are driven by diverse motives, including attempts to solve existing complex problems, the desire to create powerful new technologies that do not exist using traditional methods, and the need to create tools to address specific challenges, including those mandated by large scale science or government agency mission agendas. Many new discoveries related to communications technologies transition to wide-spread deployment through standards organizations and commercialization. These transition paths allow for new communications capabilities that drive many sectors of the digital economy. In the last few years, networking R&D has increasingly focused on advancing multiple new capabilities enabled by next generation optical networking. Both US Federal networking R&D and other national R&D initiatives, such as those organized by the National Institute of Information and Communications Technology (NICT) of Japan are creating optical networking technologies that allow for new, powerful communication services. Among the most promising services are those based on new types of multi-service or hybrid networks, which use new optical networking

  4. Annual Workshop: Higgs Couplings 2016

    CERN Document Server

    2016-01-01

    Higgs Couplings 2016 is this year's installment of an annual workshop devoted to new experimental and theoretical results on the Higgs boson. The 2016 workshop will present the latest results from the LHC run 2 on the Higgs boson mass, spin/parity, and couplings and will present new theoretical work devoted to the measurement of Higgs parameters and possibilities for exotic Higgs decays. The workshop will provide an opportunity for critical discussion of the current strategies for studying the Higgs boson at the LHC and the next steps in the LHC program. The workshop will also include discussion of the longer-term Higgs boson program at future facilities.

  5. Compressive sensing for nuclear security.

    Energy Technology Data Exchange (ETDEWEB)

    Gestner, Brian Joseph

    2013-12-01

    Special nuclear material (SNM) detection has applications in nuclear material control, treaty verification, and national security. The neutron and gamma-ray radiation signature of SNMs can be indirectly observed in scintillator materials, which fluoresce when exposed to this radiation. A photomultiplier tube (PMT) coupled to the scintillator material is often used to convert this weak fluorescence to an electrical output signal. The fluorescence produced by a neutron interaction event differs from that of a gamma-ray interaction event, leading to a slightly different pulse in the PMT output signal. The ability to distinguish between these pulse types, i.e., pulse shape discrimination (PSD), has enabled applications such as neutron spectroscopy, neutron scatter cameras, and dual-mode neutron/gamma-ray imagers. In this research, we explore the use of compressive sensing to guide the development of novel mixed-signal hardware for PMT output signal acquisition. Effectively, we explore smart digitizers that extract sufficient information for PSD while requiring a considerably lower sample rate than conventional digitizers. Given that we determine the feasibility of realizing these designs in custom low-power analog integrated circuits, this research enables the incorporation of SNM detection into wireless sensor networks.

  6. Issues in multiview autostereoscopic image compression

    Science.gov (United States)

    Shah, Druti; Dodgson, Neil A.

    2001-06-01

    Multi-view auto-stereoscopic images and image sequences require large amounts of space for storage and large bandwidth for transmission. High bandwidth can be tolerated for certain applications where the image source and display are close together but, for long distance or broadcast, compression of information is essential. We report on the results of our two- year investigation into multi-view image compression. We present results based on four techniques: differential pulse code modulation (DPCM), disparity estimation, three- dimensional discrete cosine transform (3D-DCT), and principal component analysis (PCA). Our work on DPCM investigated the best predictors to use for predicting a given pixel. Our results show that, for a given pixel, it is generally the nearby pixels within a view that provide better prediction than the corresponding pixel values in adjacent views. This led to investigations into disparity estimation. We use both correlation and least-square error measures to estimate disparity. Both perform equally well. Combining this with DPCM led to a novel method of encoding, which improved the compression ratios by a significant factor. The 3D-DCT has been shown to be a useful compression tool, with compression schemes based on ideas from the two-dimensional JPEG standard proving effective. An alternative to 3D-DCT is PCA. This has proved to be less effective than the other compression methods investigated.

  7. Metal Liner Implosions for Cylindrical Convergent Isentropic Compression of Deuterium and its Application to MAGLIF

    Science.gov (United States)

    Weinwurm, Marcus; Appelbe, Brian; Skidmore, Jonathan; Bland, Simon; Chittenden, Jeremy

    2012-10-01

    Isentropic Compression Experiments on pulsed power machines in the field of High Energy Density Physics have gained interest in recent years. We describe a method of isentropically compressing cryogenic Deuterium inside a metal liner. Pulse shaping was performed by solving Kidder's homogeneous isentropic compression for cylindrical geometry and extending it to an arbitrary Equation of State. The obtained pulse shape enables us to simulate a cylindrically convergent ramp wave, which quasi-isentropically compresses the Deuterium fill to densities much higher than achievable by using a standard pulse. The effect of Rayleigh-Taylor instabilities upon the peak density achieved is evaluated using the resistive magneto-hydrodynamics code Gorgon for a maximum current of 25 MA. Therefore, isentropic liner implosions are a promising technique for recreating the conditions present in the interiors of gas giants. We applied this technique to the High-Gain Magnetized Liner Inertial Fusion (MAGLIF) scheme [1]. There a metal liner is filled with DT gas surrounded by a layer of DT ice. We show how the current pulse can be shaped in order to isentropically compress the DT ice layer. By doing so, we keep the fuel at low temperature. This maximises the compression of the DT ice layer, and increases rho-r at stagnation. Burn wave propagation in the isentropically compressed fuel is compared to propagation in fuel compressed by a standard current pulse. [4pt] [1] S.A. Slutz and R. A. Vesey, Phys. Rev. Lett. 108, 025003 (2012)

  8. 75 FR 29775 - Food Labeling Workshop; Public Workshop

    Science.gov (United States)

    2010-05-27

    ... and startups. Date and Time: This public workshop will be held on August 4 and 5, 2010, from 8 a.m. to 5 p.m. Location: The public workshop will be held at the Continuing Education Center, 2 East Center St., Fayetteville, AR (located downtown). Contact: David Arvelo, Food and Drug...

  9. 75 FR 74736 - Food Labeling Workshop; Public Workshop

    Science.gov (United States)

    2010-12-01

    ... required due to disability, along with a check or money order for $250 payable to ``Iowa State University..., in collaboration with Iowa State University, is announcing a public workshop entitled ``Food Labeling... public workshop will be held at the Scheman Conference Center, Lincoln Way and University Avenue,...

  10. RFI Mitigation Workshop

    Science.gov (United States)

    2010-05-01

    The increased sensitivity of passive instrumentation in radio astronomy and remote sensing and the intensifying active use of the spectrum have led to an increasing level of radio frequency interference (RFI) of the active services on the passive use of the spectrum. Advances in technology and computing have opened up new possibilities for mitigating the effects of certain classes of interference in the observing data. Interference in allocated bands always leads to data loss for the passive users of the spectrum even if interference mitigation is applied. However, interference mitigation in non-allocated spectral bands may facilitate the partial use of this spectrum for passive (non-interfering) observations. There is no generic method to mitigate all types of interference, so a multi-layered system approach may be advisable to reduce detrimental effects for a congested interference environment. Specific mitigation methods implemented at different points in the data acquisition chain will thus result in a cumulative mitigation effect on the data. This third RFI Mitigation Workshop considered RFI mitigation in radio astronomy in all its facets with the aim of facilitating the implementation of instrumental and data processing techniques. This workshop aimed to take a forward look at applications for the next generation of radio instruments, such as the SKA and its pathfinders and LOFAR, as well as considering their application to existing instruments. This workshop has been organized by ASTRON and NAIC, with support from the Engineering Forum of FP7 RadioNet, the SKA Project Development Office, and in collaboration with CRAF and IUCAF.

  11. Craniofacial morphogenesis workshop report.

    Science.gov (United States)

    Solursh, M; Murray, J

    1994-05-01

    The following report highlights the discussions and interaction at the workshop on craniofacial morphogenesis, sponsored by The Human Frontier Science Program, held in April 1993 at the University of Iowa. A brief summary of selected sessions is included to exemplify the benefits of bringing together individuals from various disciplines and backgrounds in order to establish a unified theory of craniofacial morphogenesis. The synthesis of information and experience of a wide range of approaches made the 4-day period an invaluable experience for the participants from nine different countries.

  12. CENDI Indexing Workshop

    Science.gov (United States)

    1994-01-01

    The CENDI Indexing Workshop held at NASA Headquarters, Two Independence Square, 300 E Street, Washington, DC, on September 21-22, 1994 focused on the following topics: machine aided indexing, indexing quality, an indexing pilot project, the MedIndEx Prototype, Department of Energy/Office of Scientific and Technical Information indexing activities, high-tech coding structures, category indexing schemes, and the Government Information Locator Service. This publication consists mostly of viewgraphs related to the above noted topics. In an appendix is a description of the Government Information Locator Service.

  13. Melioidosis Diagnostic Workshop, 20131

    Science.gov (United States)

    AuCoin, David; Baccam, Prasith; Baggett, Henry C.; Baird, Rob; Bhengsri, Saithip; Blaney, David D.; Brett, Paul J.; Brooks, Timothy J.G.; Brown, Katherine A.; Chantratita, Narisara; Cheng, Allen C.; Dance, David A.B.; Decuypere, Saskia; Defenbaugh, Dawn; Gee, Jay E.; Houghton, Raymond; Jorakate, Possawat; Lertmemongkolchai, Ganjana; Limmathurotsakul, Direk; Merlin, Toby L.; Mukhopadhyay, Chiranjay; Norton, Robert; Peacock, Sharon J.; Rolim, Dionne B.; Simpson, Andrew J.; Steinmetz, Ivo; Stoddard, Robyn A.; Stokes, Martha M.; Sue, David; Tuanyok, Apichai; Whistler, Toni; Wuthiekanun, Vanaporn; Walke, Henry T.

    2015-01-01

    Melioidosis is a severe disease that can be difficult to diagnose because of its diverse clinical manifestations and a lack of adequate diagnostic capabilities for suspected cases. There is broad interest in improving detection and diagnosis of this disease not only in melioidosis-endemic regions but also outside these regions because melioidosis may be underreported and poses a potential bioterrorism challenge for public health authorities. Therefore, a workshop of academic, government, and private sector personnel from around the world was convened to discuss the current state of melioidosis diagnostics, diagnostic needs, and future directions. PMID:25626057

  14. SIMS applications workshop. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    The first ANSTO/AINSE SIMS Workshop drew together a mixture of Surface Analysis experts and Surface Analysis users with the concept that SIMS analysis has to be enfolded within the spectrum of surface analysis techniques and that the user should select the technique most applicable to the problem. With this concept in mind the program was structured as sessions on SIMS Facilities; Applications to Mineral Surfaces; Applications to Biological Systems, Applications to Surfaces as Semi- conductors, Catalysts and Surface Coatings; and Applications to Ceramics

  15. ROOT User Workshop 2013

    CERN Document Server

    2013-01-01

    Since almost two decades, ROOT has established itself as the framework for HENP data processing and analysis. The LHC upgrade program and the new experiments being designed at CERN and elsewhere will pose even more formidable challenges in terms of data complexity and size. The new parallel and heterogeneous computing architectures that are either announced or already available will call for a deep rethinking of the code and the data structures to be exploited efficiently. This workshop, following from a successful series of such events, will allow you to learn in detail about the new ROOT 6 and will help shape the future evolution of ROOT.

  16. 15th Cluster workshop

    CERN Document Server

    Laakso, Harri; Escoubet, C. Philippe; The Cluster Active Archive : Studying the Earth’s Space Plasma Environment

    2010-01-01

    Since the year 2000 the ESA Cluster mission has been investigating the small-scale structures and processes of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. This book contains presentations made at the 15th Cluster workshop held in March 2008. It also presents several articles about the Cluster Active Archive and its datasets, a few overview papers on the Cluster mission, and articles reporting on scientific findings on the solar wind, the magnetosheath, the magnetopause and the magnetotail.

  17. Workshop Polli Talu Loomingulises Keskuses

    Index Scriptorium Estoniae

    2004-01-01

    MAP Intermedia Performance Collaboration'i (USA) workshop. Brendan McCall (liikumine), N. B. Aldrich (heli) ja Zach Poff (video) workshop tutvustab kolme kunstniku koostööd. Näidatakse ka multimeedia etendust, mis on külaliskunstnikel valminud Polli talus

  18. A Portable Computer Security Workshop

    Science.gov (United States)

    Wagner, Paul J.; Phillips, Andrew T.

    2006-01-01

    We have developed a computer security workshop designed to instruct post-secondary instructors who want to start a course or laboratory exercise sequence in computer security. This workshop has also been used to provide computer security education to IT professionals and students. It is effective in communicating basic computer security principles…

  19. New technology integration planning workshop

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    Purpose of the Workshop was to provide guidance, reflecting electric utility industry viewpoints, for developing and directing its research and development program structures to facilitate the integration of new energy technologies into electric utility systems. The Workshop was structured to directly elicit the positions and viewpoints representative of electric utility companies.

  20. Hydrogen Technology Education Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-12-01

    This document outlines activities for educating key target audiences, as suggested by workshop participants. Held December 4-5, 2002, the Hydrogen Technology Education Workshop kicked off a new education effort coordinated by the Hydrogen, Fuel Cells, & Infrastructure Technologies Program of the Office of Energy Efficiency and Renewable Energy.

  1. Beta Cell Workshop 2013 Kyoto

    DEFF Research Database (Denmark)

    Heller, R Scott; Madsen, Ole D; Nielsen, Jens Høiriis

    2013-01-01

    The very modern Kyoto International Conference Center provided the site for the 8th workshop on Beta cells on April 23-26, 2013. The preceding workshops were held in Boston, USA (1991); Kyoto, Japan (1994); Helsingør, Denmark (1997); Helsinki, Finland (2003); El Perello, Spain (2006); Peebles...

  2. Workshop Polli Talu Loomingulises Keskuses

    Index Scriptorium Estoniae

    2004-01-01

    MAP Intermedia Performance Collaboration'i (USA) workshop. Brendan McCall (liikumine), N. B. Aldrich (heli) ja Zach Poff (video) workshop tutvustab kolme kunstniku koostööd. Näidatakse ka multimeedia etendust, mis on külaliskunstnikel valminud Polli talus

  3. Presentation Skills Workshops for Nurses.

    Science.gov (United States)

    Kinn, S.; Kenyon, M.

    2002-01-01

    Workshops were held to prepare nurses (n=87) to present results of professional activities. One year after the course, 20 had made oral and 30 written presentations. The workshops increased their confidence and were considered practical, informal, and nonthreatening. (Contains 31 references.) (SK)

  4. Marketing Cooperative Education. A Workshop.

    Science.gov (United States)

    Mosser, John W.; Rea, Peter J.

    This document is a guide for a workshop on marketing college cooperative education programs. The guide takes the reader/workshop participant through the marketing process, from defining needs and resources to planning a marketing campaign, implementing it, and evaluating its success. Samples and sources also are provided. Topics covered in the…

  5. Femtosecond electron pulse generation and measurement for diffractive imaging of isolated molecules

    Science.gov (United States)

    Zandi, Omid; Wilkin, Kyle J.; DeSimone, Alice J.; Yang, Jie; Centurion, Martin

    2016-09-01

    We have constructed an electron gun that delivers highly charged femtosecond electron pulses to a target with kHz repetition rate. Electron pulses are generated by femtosecond laser pulses in a photoemission process and are accelerated up to 100 kV and compressed to sub-picosecond duration. Compression is essential to compensate for the space charge effect that increases the size of electron pulses in all directions significantly. The pulses are compressed transversely by magnetic lenses and longitudinally by the longitudinal electric field of a radio-frequency cavity. The longitudinal compression is achieved by decelerating the electrons in the leading edge of the pulse, and accelerating the electrons in the trailing edge of the pulse. This results in the pulse compressing and reaching the minimum pulse duration at a known distance from the compression cavity. The short pulse duration and high repetition rate will be essential to observe subpicosecond dynamic processes in molecules in gas phase with a good signal to noise ratio. A streak camera, consisting of a millimeter-sized parallel plate capacitor, was used to measure the pulse duration in situ.

  6. Pulse Voltammetry.

    Science.gov (United States)

    Osteryoung, Janet

    1983-01-01

    Discusses the nature of pulse voltammetry, indicating that its widespread use arises from good sensitivity and detection limits and from ease of application and low cost. Provides analytical and mechanistic applications of the procedure. (JN)

  7. First JECSS Workshop

    Science.gov (United States)

    Ichiye, Takashi

    The first Japan and East China Seas Study (JECSS) workshop convened at Tsukuba University, about 60 km north of Tokyo, Japan, June 1-4, 1981, to assess hydrographic data, review descriptive and theoretical Work, and promote future cooperation for studying the Japan Sea and East China Sea and marginal seas of the Western North Pacific Ocean. The conveners were Takashi Ichiye of Texas A&M University and Kenzo Takano of Tsukuba University, and the workshop was funded by the Hidaka Foundation, which was founded by Koji Hidaka, patriarch of dynamic oceanography in Japan.There were 41 participants: seven from the United States, six from Korea, one from the Peoples Republic of China, and 27 from Japan. Twenty-four papers were presented, and topics included the Japan Sea, the East China Sea, and marginal seas in general. Subjects concerned descriptive physical oceanography; internal waves, tides, and shelf waves; circulation modeling; data assessment; remote sensing; and sedimentology and marine chemistry. The seasonal change of the Tsushima Current, a branch of the Kuroshio in the Japan Sea, was determined by the Tohoku University group; preliminary results of the NOAA R/V Oceanographer cruise in Spring 1980 were presented; and the numerical modeling of the Japan Sea circulation, the tides of the Yellow Sea, and the barotropic current of the East China Sea were discussed. The papers presented will be published in 1982 in La Mer, a journal of the Japanese-French Oceanographical Society.

  8. GammaWorkshops Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Ramebaeck, H. (ed.) (Swedish Defence Research Agency (Sweden)); Straalberg, E. (Institute for Energy Technology, Kjeller (Norway)); Klemola, S. (Radiation and Nuclear Safety Authority, STUK (Finland)); Nielsen, Sven P. (Technical Univ. of Denmark. Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Palsson, S.E. (Icelandic Radiation Safety Authority (Iceland))

    2012-01-15

    Due to a sparse interaction during the last years between practioners in gamma ray spectrometry in the Nordic countries, a NKS activity was started in 2009. This GammaSem was focused on seminars relevant to gamma spectrometry. A follow up seminar was held in 2010. As an outcome of these activities it was suggested that the 2011 meeting should be focused on practical issues, e.g. different corrections needed in gamma spectrometric measurements. This three day's meeting, GammaWorkshops, was held in September at Risoe-DTU. Experts on different topics relevant for gamma spectrometric measurements were invited to the GammaWorkshops. The topics included efficiency transfer, true coincidence summing corrections, self-attenuation corrections, measurement of natural radionuclides (natural decay series), combined measurement uncertainty calculations, and detection limits. These topics covered both lectures and practical sessions. The practical sessions included demonstrations of tools for e.g. corrections and calculations of the above meantioned topics. (Author)

  9. Cascaded quadratic soliton compression of high-power femtosecond fiber lasers in Lithium Niobate crystals

    DEFF Research Database (Denmark)

    Bache, Morten; Moses, Jeffrey; Wise, Frank W.

    2008-01-01

    The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs.......The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs....

  10. Developing an artificial neural network model for predicting concrete’s compression strength and electrical resistivity

    Directory of Open Access Journals (Sweden)

    Juan Manuel Lizarazo Marriaga

    2010-04-01

    Full Text Available The present study was conducted for predicting the compressive strength of concrete based on unit weight ultrasonic and pulse velocity (UPV for 41 different concrete mixtures. This research emerged from the need for a rapid test for predicting concrete’s compressive strength. The research was also conducted for predicting concrete’s electrical resistivity based on unit weight ultrasonic, pulse velocity (UPV and compressive strength with the same mixes. The prediction was made using simple regression analysis and artificial neural networks. The results revealed that artificial neural networks can be used for effectively predicting compressive strength and electrical resistivity.

  11. Generation of high harmonics and attosecond pulses with ultrashort laser pulse filaments and conical waves

    Indian Academy of Sciences (India)

    A Couairon; A Lotti; D Faccio; P Di Trapani; D S Steingrube; E Schulz; T Binhammer; U Morgner; M Kovacev; M B Gaarde

    2014-08-01

    Results illustrating the nonlinear dynamics of ultrashort laser pulse filamentation in gases are presented, with particular emphasis on the filament properties useful for developing attosecond light sources. Two aspects of ultrashort pulse filaments are specifically discussed: (i) numerical simulation results on pulse self-compression by filamentation in a gas cell filled with noble gas. Measurements of high harmonics generated by the pulse extracted from the filament allows for the detection of intensity spikes and subcycle pulses generated within the filament. (ii) Simulation results on the spontaneous formation of conical wavepackets during filamentation in gases, which in turn can be used as efficient driving pulses for the generation of high harmonics and isolated attosecond pulses.

  12. Generation of Single-Cycle Light Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, B C; Jovanovic, I; Armstrong, J P; Pyke, B; Crane, J K; Shuttlesworth, R

    2004-02-13

    Most optical pulses, even at the 10-femtosecond timescale, consist of several oscillations of the electric field. By producing and amplifying an ultra-broadband continuum, single cycle (e 3 fs) or shorter optical pulses may be generated. This requires a very challenging pulse-compression with sub-femtosecond accuracy. Production of these single-cycle pulses will lead to new generations of experiments in the areas of coherent control of chemical excitations and reactions, 0.1-fs high-order harmonic (XUV) generation for probing of materials and fast processes, and selective 3-D micron-scale material removal and modification. We activated the first stage of a planned three-stage optical parametric amplifier (OPA) that would ultimately produce sub-3 fs pulses. Active control with a learning algorithm was implemented to optimize the continuum generated in an argon-filled capillary and to control and optimize the final compressed pulse temporal shape. A collaboration was initiated to coherently control the population of different states upon dissociation of Rb{sub 2}. Except for one final optic, a pulse compressor and diagnostics were constructed to produce and characterize pulses in the 5-fs range from the first OPA stage.

  13. Workshop on scientific applications of coherent x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, J.; Materlik, G.; Winick, H. [Stanford Univ., CA (United States). Stanford Linear Accelerator Center]|[Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.; Birgeneau, R.J. [Massachusetts Institute of Technology, Cambridge, MA (United States); Fadley, C.S. [Lawrence Berkeley Lab., CA (United States). Materials Science Division

    1994-02-12

    This is a report on a workshop held at SLAC on February 12, 1994 to assess the science that would become possible using high peak power, short pulses of coherent radiation from a Free Electron Laser (FEL) operating in the hard x-ray region, at wavelengths down to about 1 {angstrom}. Sixty-three people participated in the workshop. The appendices to this report give a list of participants, the workshop agenda, and the charge to the workshop. Material describing the performance parameters of several possible sources was made available to the participants along with a graph showing the spectral distribution of the spontaneous as well as the coherent radiation and a note on peak power issues. This material is also included as an appendix to this report. This report consists of an Executive Summary, brief summaries by the speaker for each of the talks that were given, and copies of some of the viewgraphs that were shown. Also included are important points raised in the discussions that followed each talk. In addition, two contributions from scientists who could not attend the workshop are included, plus one contribution received from a participant after the workshop. A serious storm on the East coast made it impossible for three speakers and several intended participants to reach Stanford. The talk by Janos Kirz was presented by Malcolm Howells using viewgraphs sent by FAX. The talks by Keith Nelson and Brian Stephenson were not given. We include summaries by them of the talks they would have given, plus copies of some of their viewgraphs, in this report.

  14. Lossless Medical Image Compression

    Directory of Open Access Journals (Sweden)

    Nagashree G

    2014-06-01

    Full Text Available Image compression has become an important process in today‟s world of information exchange. Image compression helps in effective utilization of high speed network resources. Medical Image Compression is very important in the present world for efficient archiving and transmission of images. In this paper two different approaches for lossless image compression is proposed. One uses the combination of 2D-DWT & FELICS algorithm for lossy to lossless Image Compression and another uses combination of prediction algorithm and Integer wavelet Transform (IWT. To show the effectiveness of the methodology used, different image quality parameters are measured and shown the comparison of both the approaches. We observed the increased compression ratio and higher PSNR values.

  15. 星载气象雷达功放非线性对超低副瓣脉冲压缩信号的影响及消除%Power Amplifier Predistortion on Pulse Compression with Very Low Sidelobes for Spaceborne Weather Radar

    Institute of Scientific and Technical Information of China (English)

    朱迪; 董晓龙

    2009-01-01

    为在强海面回波影响下测量反射较弱的雨云.星载气象雷达要求脉冲压缩的主副瓣功率比高于60 dB.因此超低副瓣脉冲压缩成为星载气象雷达的核心技术之一.超低副瓣的实现对线性度要求很高.星载雷达为保证发射机的功率和效率,功放多工作于近饱和区,造成副瓣电平恶化.本文分析了功放非线性对超低副瓣脉冲压缩信号的影响,基于射频功率放大器、矢量信号发生仪和矢量信号分析仪实现了功放数字预失真算法,并利用松弛迭代法提高了迭代收敛速度.在保证星载气象雷达超低副瓣的前提下提高了发射机的功效.%The pulse compression with very low sidelobes is one of challenges in the design of the spaceborne weather radar.To detect the wcak echoes of clouds occurred near the strong echoes of the sea surface,the sidelobe performance below-60 dB is needed in the pulse compression system.To achieve such low sidelobes,the high linearity is required in the radar system.But in spaceborne radar system.the transmitter often works at saturation point to obtain the high output power and the efficiency.So a successive overrelaxation(SOR)iterative method of the digital predistortion is used to ensure the low sidelobe performance,the high output power and the fast iterative speed.A test system based on RFPA,electronic signal generator and vector signal analyzer is used to verify and optimize the predistortion algorithm.

  16. Celiac Artery Compression Syndrome

    Directory of Open Access Journals (Sweden)

    Mohammed Muqeetadnan

    2013-01-01

    Full Text Available Celiac artery compression syndrome is a rare disorder characterized by episodic abdominal pain and weight loss. It is the result of external compression of celiac artery by the median arcuate ligament. We present a case of celiac artery compression syndrome in a 57-year-old male with severe postprandial abdominal pain and 30-pound weight loss. The patient eventually responded well to surgical division of the median arcuate ligament by laparoscopy.

  17. Spectral compression of single photons

    CERN Document Server

    Lavoie, Jonathan; Wright, Logan G; Fedrizzi, Alessandro; Resch, Kevin J

    2013-01-01

    Photons are critical to quantum technologies since they can be used for virtually all quantum information tasks: in quantum metrology, as the information carrier in photonic quantum computation, as a mediator in hybrid systems, and to establish long distance networks. The physical characteristics of photons in these applications differ drastically; spectral bandwidths span 12 orders of magnitude from 50 THz for quantum-optical coherence tomography to 50 Hz for certain quantum memories. Combining these technologies requires coherent interfaces that reversibly map centre frequencies and bandwidths of photons to avoid excessive loss. Here we demonstrate bandwidth compression of single photons by a factor 40 and tunability over a range 70 times that bandwidth via sum-frequency generation with chirped laser pulses. This constitutes a time-to-frequency interface for light capable of converting time-bin to colour entanglement and enables ultrafast timing measurements. It is a step toward arbitrary waveform generatio...

  18. Compressed sensing & sparse filtering

    CERN Document Server

    Carmi, Avishy Y; Godsill, Simon J

    2013-01-01

    This book is aimed at presenting concepts, methods and algorithms ableto cope with undersampled and limited data. One such trend that recently gained popularity and to some extent revolutionised signal processing is compressed sensing. Compressed sensing builds upon the observation that many signals in nature are nearly sparse (or compressible, as they are normally referred to) in some domain, and consequently they can be reconstructed to within high accuracy from far fewer observations than traditionally held to be necessary. Apart from compressed sensing this book contains other related app

  19. Wavelet image compression

    CERN Document Server

    Pearlman, William A

    2013-01-01

    This book explains the stages necessary to create a wavelet compression system for images and describes state-of-the-art systems used in image compression standards and current research. It starts with a high level discussion of the properties of the wavelet transform, especially the decomposition into multi-resolution subbands. It continues with an exposition of the null-zone, uniform quantization used in most subband coding systems and the optimal allocation of bitrate to the different subbands. Then the image compression systems of the FBI Fingerprint Compression Standard and the JPEG2000 S

  20. Stiffness of compression devices

    Directory of Open Access Journals (Sweden)

    Giovanni Mosti

    2013-03-01

    Full Text Available This issue of Veins and Lymphatics collects papers coming from the International Compression Club (ICC Meeting on Stiffness of Compression Devices, which took place in Vienna on May 2012. Several studies have demonstrated that the stiffness of compression products plays a major role for their hemodynamic efficacy. According to the European Committee for Standardization (CEN, stiffness is defined as the pressure increase produced by medical compression hosiery (MCH per 1 cm of increase in leg circumference.1 In other words stiffness could be defined as the ability of the bandage/stockings to oppose the muscle expansion during contraction.

  1. The Third ATLAS ROD Workshop

    CERN Multimedia

    Poggioli, L.

    A new-style Workshop After two successful ATLAS ROD Workshops dedicated to the ROD hardware and held at the Geneva University in 1998 and in 2000, a new style Workshop took place at LAPP in Annecy on November 14-15, 2002. This time the Workshop was fully dedicated to the ROD-TDAQ integration and software in view of the near future integration activities of the final RODs for the detector assembly and commissioning. More precisely, the aim of this workshop was to get from the sub-detectors the parameters needed for T-DAQ, as well as status and plans from ROD builders. On the other hand, what was decided and assumed had to be stated (like EB decisions and URDs), and also support plans. The Workshop gathered about 70 participants from all ATLAS sub-detectors and the T-DAQ community. The quite dense agenda allowed nevertheless for many lively discussions, and for a dinner in the old town of Annecy. The Sessions The Workshop was organized in five main sessions: Assumptions and recommendations Sub-de...

  2. LIBER-EBLIDA Digitisation Workshop

    Directory of Open Access Journals (Sweden)

    Paul Ayris

    2008-03-01

    Full Text Available 95 participants from 23 countries attended a Workshop on the Digitisation of Library Material in Europe, from 24 to 26 October 2007 in the Royal Library, Copenhagen, Denmark. The Workshop was jointly organised by LIBER and EBLIDA. In a full report on the Workshop on the JISC website, the JISC highlighted that ‘high on the agenda were moves towards a European Digital Library – the delivery of integrated access to the digitised collections of libraries, archives and museums across the EU.’ At a global level, this was indeed one of the main aims of the Workshop. As the Chair of the breakout groups, and the final session of the Workshop, I gave an interview for the JISC immediately after the final session where I looked at what I thought were some of the issues to be identified by the Workshop. The purpose of this paper is to describe some of these issues in a little more detail and outline what work LIBER and EBLIDA have undertaken in the wake of the significant momentum which the Workshop has engendered for European digitisation activity.

  3. Spatiotemporal dynamics of Gaussian laser pulse in a multi ions plasma

    Science.gov (United States)

    Jafari Milani, M. R.

    2016-08-01

    Spatiotemporal evolutions of Gaussian laser pulse propagating through a plasma with multiple charged ions are studied, taking into account the ponderomotive nonlinearity. Coupled differential equations for beam width and pulse length parameters are established and numerically solved using paraxial ray approximation. In one-dimensional geometry, effects of laser and plasma parameters such as laser intensity, plasma density, and temperature on the longitudinal pulse compression and the laser intensity distribution are analyzed for plasmas with singly and doubly charged ions. The results demonstrate that self-compression occurs in a laser intensity range with a turning point intensity in which the self-compression process has its strongest extent. The results also show that the multiply ionized ions have different effect on the pulse compression above and below turning point intensity. Finally, three-dimensional geometry is used to analyze the simultaneous evolution of both self-focusing and self-compression of Gaussian laser pulse in such plasmas.

  4. STUCTURE OF PULSED BED

    Directory of Open Access Journals (Sweden)

    I. A. Bokun

    2014-01-01

    Full Text Available The structure of pulsed layer is proposed which can be suggested as a state of particulates that is blown by intermittent gas flow with speed which has the force to start material moving. Layer during one cycle is in a suspension, falling down and immobile state resulting in changes of particles arrangement as well as ways of gas flowing through layer. Moreover, it allows carrying out effective interphase heat exchange even adamant real granulation.The process of formation of impact flows is considered aw well as their influence on formation of air bubbles in pulsed layer. At startup of air blast the balance between the force of hydro-dynamic resistance is broken, on one side, and forces of gravity, particles inertia and their links with walls on the other side. The layer is transferred in the state of pulsed pseudo-fluidization, and presents gas-disperse mixture, inside of which impulse of pressure increasing is spreading to all sides as pressure waves (compression. These waves are the sources of impact flows’ formation, the force of which is two times more than during the stationary flow.The waves of pressure are divided into weak and strong ones depending on movement velocity within gas-disperse system. Weak waves are moving with a sound speed and strong ones in active phase of pulsed layer are moving over the speed of sound limit within gas-disperse system. The peculiarity of strong wave is that parameters of system (pressure, density and others are changing in discrete steps.The article describes the regime of layer’s falling down in the passive stage of cycle, which begins after finishing of gas impulse action. And suspension layer of moving up granular material is transferred in the state of falling resulting in change of the layer structure.

  5. Excitation of spin echo by pulses with linear frequency modulation

    Science.gov (United States)

    Baruzdin, S. A.

    2015-03-01

    The excitation of a spin echo by two pulses with linear frequency modulation, upon which the pulse parameters ensure maximal compression of the response in time, is considered. The frequency of the excitation pulses was changed by a step law, approximating its linear rise. The transfer matrix of the state of the spin system for pulses with linear frequency modulation is found by solving the Bloch equations. The shape of the envelope of the spin echo in thin magnetic cobalt films, as well as the dependence of the echo amplitude on the parameters of the excitation pulses, is determined. The amplitudes of the excitation pulses, which ensure the excitation of the echo maximal amplitude for various values of the frequency deviation, are found. It is shown that the use of pulses with linear frequency modulation makes it possible to obtain the same echo amplitude as with the use of simple excitation pulses for a substantially smaller amplitude and power of excitation pulses.

  6. Virtually Lossless Compression of Astrophysical Images

    Directory of Open Access Journals (Sweden)

    Alparone Luciano

    2005-01-01

    Full Text Available We describe an image compression strategy potentially capable of preserving the scientific quality of astrophysical data, simultaneously allowing a consistent bandwidth reduction to be achieved. Unlike strictly lossless techniques, by which moderate compression ratios are attainable, and conventional lossy techniques, in which the mean square error of the decoded data is globally controlled by users, near-lossless methods are capable of locally constraining the maximum absolute error, based on user's requirements. An advanced lossless/near-lossless differential pulse code modulation (DPCM scheme, recently introduced by the authors and relying on a causal spatial prediction, is adjusted to the specific characteristics of astrophysical image data (high radiometric resolution, generally low noise, etc.. The background noise is preliminarily estimated to drive the quantization stage for high quality, which is the primary concern in most of astrophysical applications. Extensive experimental results of lossless, near-lossless, and lossy compression of astrophysical images acquired by the Hubble space telescope show the advantages of the proposed method compared to standard techniques like JPEG-LS and JPEG2000. Eventually, the rationale of virtually lossless compression, that is, a noise-adjusted lossles/near-lossless compression, is highlighted and found to be in accordance with concepts well established for the astronomers' community.

  7. Workshop Econophys-2015

    CERN Document Server

    Aoyama, Hideaki; Chakrabarti, Bikas; Chakraborti, Anirban; Deo, Nivedita; Raina, Dhruv; Vodenska, Irena

    2017-01-01

    This book presents the proceedings from ECONOPHYS-2015, an international workshop held in New Delhi, India, on the interrelated fields of “econophysics” and “sociophysics”, which have emerged from the application of statistical physics to economics and sociology. Leading researchers from varied communities, including economists, sociologists, financial analysts, mathematicians, physicists, statisticians, and others, report on their recent work, discuss topical issues, and review the relevant contemporary literature. A society can be described as a group of people who inhabit the same geographical or social territory and are mutually involved through their shared participation in different aspects of life. It is possible to observe and characterize average behaviors of members of a society, an example being voting behavior. Moreover, the dynamic nature of interaction within any economic sector comprising numerous cooperatively interacting agents has many features in common with the interacting systems ...

  8. Workshop on Teaching Thermodynamics

    CERN Document Server

    1985-01-01

    It seemed appropriate to arrange a meeting of teachers of thermodynamics in the United Kingdom, a meeting held in the pleasant surroundings of Emmanuel College, Cambridge, in Sept~mber, 1984. This volume records the ideas put forward by authors, the discussion generated and an account of the action that discussion has initiated. Emphasis was placed on the Teaching of Thermodynamics to degree-level students in their first and second years. The meeting, a workshop for practitioners in which all were expected to take part, was remarkably well supported. This was notable in the representation of essentially every UK university and polytechnic engaged in teaching engineering thermodynamics and has led to a stimulating spread of ideas. By intention, the emphasis for attendance was put on teachers of engineering concerned with thermodynamics, both mechanical and chemical engineering disciplines. Attendance from others was encouraged but limited as follows: non-engineering acad­ emics, 10%, industrialists, 10%. The ...

  9. 2010 ENLIGHT Workshops

    CERN Multimedia

    ENLIGHT - European Network for LIGht ion Hadron Therapy; Manuela Cirilli

    2010-01-01

    ENLIGHT was established in 2002 to coordinate the European efforts in hadron therapy. Manjit Dosanjh, CERN’s Life Sciences Advisor (KTT), is also co-ordinator of the ENLIGHT network and some of the related programs. Under the umbrella of ENLIGHT, there are currently four EC-funded projects; PARTNER, ENVISION and ENTERVISION, co-ordinated by CERN and ULICE, co-ordinated by CNAO. The video brings you to the prestigious Nobel Forum at the Karolinska Institutet in Stockholm, where the ENLIGHT community gathered in September 2010 for the annual workshop. Meet the young researchers of the PARTNER Initial Training Network, and learn about the outcome of the Mid Term Review of the project conducted by the European Commission.

  10. Workshop on Interface Phenomena

    CERN Document Server

    Kreuzer, Hans

    1987-01-01

    This book contains the proceedings of the first Workshop on Interface Phenomena, organized jointly by the surface science groups at Dalhousie University and the University of Maine. It was our intention to concentrate on just three topics related to the kinetics of interface reactions which, in our opinion, were frequently obscured unnecessarily in the literature and whose fundamental nature warranted an extensive discussion to help clarify the issues, very much in the spirit of the Discussions of the Faraday Society. Each session (day) saw two principal speakers expounding the different views; the session chairmen were asked to summarize the ensuing discussions. To understand the complexity of interface reactions, paradigms must be formulated to provide a framework for the interpretation of experimen­ tal data and for the construction of theoretical models. Phenomenological approaches have been based on a small number of rate equations for the concentrations or mole numbers of the various species involved i...

  11. Workshop on Computational Optimization

    CERN Document Server

    2016-01-01

    This volume is a comprehensive collection of extended contributions from the Workshop on Computational Optimization 2014, held at Warsaw, Poland, September 7-10, 2014. The book presents recent advances in computational optimization. The volume includes important real problems like parameter settings for controlling processes in bioreactor and other processes, resource constrained project scheduling, infection distribution, molecule distance geometry, quantum computing, real-time management and optimal control, bin packing, medical image processing, localization the abrupt atmospheric contamination source and so on. It shows how to develop algorithms for them based on new metaheuristic methods like evolutionary computation, ant colony optimization, constrain programming and others. This research demonstrates how some real-world problems arising in engineering, economics, medicine and other domains can be formulated as optimization tasks.

  12. Student interaction in workshops

    DEFF Research Database (Denmark)

    Evers, Winie

    2014-01-01

    A kind of teaching for active learning has been experimented with at SDU Sønderborg as part of the course Supply Chain Dynamics. In this course the students learn about complex systems, system dynamics as well as supply chain instability and oscillation, the course lecturer invited the author...... to experiment with novel workshop methods and techniques, where objects are used to illustrate and model business issues (Heinemann et al, 2011, Buur et al, 2013). The idea was to see how students could be engaged in a different and more interactive way to learn about these topics, by assigning the students...... teaching should reflect this diversity by embracing and experimenting with multiple forms, including activation of students by students’ interaction and manipulation with objects....

  13. Workshop on Computational Optimization

    CERN Document Server

    2015-01-01

    Our everyday life is unthinkable without optimization. We try to minimize our effort and to maximize the achieved profit. Many real world and industrial problems arising in engineering, economics, medicine and other domains can be formulated as optimization tasks. This volume is a comprehensive collection of extended contributions from the Workshop on Computational Optimization 2013. It presents recent advances in computational optimization. The volume includes important real life problems like parameter settings for controlling processes in bioreactor, resource constrained project scheduling, problems arising in transport services, error correcting codes, optimal system performance and energy consumption and so on. It shows how to develop algorithms for them based on new metaheuristic methods like evolutionary computation, ant colony optimization, constrain programming and others.

  14. 2016 MICCAI Workshop

    CERN Document Server

    Ghosh, Aurobrata; Kaden, Enrico; Rathi, Yogesh; Reisert, Marco

    2017-01-01

    This volume offers a valuable starting point for anyone interested in learning computational diffusion MRI and mathematical methods for brain connectivity, while also sharing new perspectives and insights on the latest research challenges for those currently working in the field. Over the last decade, interest in diffusion MRI has virtually exploded. The technique provides unique insights into the microstructure of living tissue and enables in-vivo connectivity mapping of the brain. Computational techniques are key to the continued success and development of diffusion MRI and to its widespread transfer into the clinic, while new processing methods are essential to addressing issues at each stage of the diffusion MRI pipeline: acquisition, reconstruction, modeling and model fitting, image processing, fiber tracking, connectivity mapping, visualization, group studies and inference. These papers from the 2016 MICCAI Workshop “Computational Diffusion MRI” – which was intended to provide a snapshot of the la...

  15. 2014 MICCAI Workshop

    CERN Document Server

    Nedjati-Gilani, Gemma; Rathi, Yogesh; Reisert, Marco; Schneider, Torben

    2014-01-01

    This book contains papers presented at the 2014 MICCAI Workshop on Computational Diffusion MRI, CDMRI’14. Detailing new computational methods applied to diffusion magnetic resonance imaging data, it offers readers a snapshot of the current state of the art and covers a wide range of topics from fundamental theoretical work on mathematical modeling to the development and evaluation of robust algorithms and applications in neuroscientific studies and clinical practice.   Inside, readers will find information on brain network analysis, mathematical modeling for clinical applications, tissue microstructure imaging, super-resolution methods, signal reconstruction, visualization, and more. Contributions include both careful mathematical derivations and a large number of rich full-color visualizations.   Computational techniques are key to the continued success and development of diffusion MRI and to its widespread transfer into the clinic. This volume will offer a valuable starting point for anyone interested i...

  16. NOMA 2013 International Workshop

    CERN Document Server

    Fournier-Prunaret, Danièle; Nishio, Yoshifumi; Grácio, Clara

    2015-01-01

    In the field of Dynamical Systems, nonlinear iterative processes play an important role. Nonlinear mappings can be found as immediate models for many systems from different scientific areas, such as engineering, economics, biology, or can also be obtained via numerical methods permitting to solve non-linear differential equations. In both cases, the understanding of specific dynamical behaviors and phenomena is of the greatest interest for scientists. This volume contains papers that were presented at the International Workshop on Nonlinear Maps and their Applications (NOMA 2013) held in Zaragoza, Spain, on September 3-4, 2013. This kind of collaborative effort is of paramount importance in promoting communication among the various groups that work in dynamical systems and networks in their research theoretical studies as well as for applications. This volume is suitable for graduate students as well as researchers in the field.

  17. Summary of the PSI workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-03-01

    The PSI workshop had been held at JAERI-Naka, from March 15th to 16th, 2002. This workshop is held twice a year as the skull practice session to report the recent progress on the plasma - surface interactions of the experimental reactors such as ITER, JT-60, LHD, etc. and the development of the plasma facing components. There were 34 participants from the university and 18 participants from JAERI and 26 papers were presented. This booklet was published for the purpose of saving a record of this workshop performed in oral lecture form. (author)

  18. The Astronomy Workshop

    Science.gov (United States)

    Hamilton, Douglas P.

    2013-05-01

    Abstract (2,250 Maximum Characters): The Astronomy Workshop (http://janus.astro.umd.edu) is a collection of interactive online educational tools developed for use by students, educators, professional astronomers, and the general public. The more than 20 tools in the Astronomy Workshop are rated for ease-of-use, and have been extensively tested in large university survey courses as well as more specialized classes for undergraduate majors and graduate students. Here we briefly describe the tools most relevant for the Professional Dynamical Astronomer. Solar Systems Visualizer: The orbital motions of planets, moons, and asteroids in the Solar System as well as many of the planets in exoplanetary systems are animated at their correct relative speeds in accurate to-scale drawings. Zoom in from the chaotic outer satellite systems of the giant planets all the way to their innermost ring systems. Orbital Integrators: Determine the orbital evolution of your initial conditions for a number of different scenarios including motions subject to general central forces, the classic three-body problem, and satellites of planets and exoplanets. Zero velocity curves are calculated and automatically included on relevant plots. Orbital Elements: Convert quickly and easily between state vectors and orbital elements with Changing the Elements. Use other routines to visualize your three-dimensional orbit and to convert between the different commonly used sets of orbital elements including the true, mean, and eccentric anomalies. Solar System Calculators: These tools calculate a user-defined mathematical expression simultaneously for all of the Solar System's planets (Planetary Calculator) or moons (Satellite Calculator). Key physical and orbital data are automatically accessed as needed.

  19. 77 FR 12313 - Food Labeling Workshop; Public Workshop

    Science.gov (United States)

    2012-02-29

    ... University (OSU), Robert M. Kerr Food & Agricultural Products Center (FAPC), is announcing a public workshop... special accommodations due to a disability, please contact Karen Smith (see Contact) at least 7 days...

  20. Proceedings of the Santa Fe workshop on electron effects

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T.S.; Jason, A. [eds.

    1998-11-01

    The Workshop was held under the sponsorship of the Spallation Neutron Source (SNS) Project to further project understanding of the effects and cause of the presence of electrons in proton accelerators. In particular, the fast instability seen in the Los Alamos Proton Storage Ring was the major topic of discussion since it limits the particles/pulse to the LANSCE target and could have an impact on the SNS Ring. This instability is believed due to the interaction of trapped electrons in the accumulated beam, i.e., an electron-proton or e-p instability. The first day of the workshop was occupied by invited talks that included a review of e-p instability theory, an overview of PSR observations, observations at other laboratories, reviews of electron-production mechanisms, theoretical studies on the PSR instability, and design issues of the SNS ring. For the second day, the workshop was organized into three working groups: a theory and computation group, a past-experiences and proposed-experiments group, and the SNS-design-strategy group. Their charter was to summarize previous work in their respective areas and to originate a course for future progress. The results of the working groups and the workshop were summarized in a joint session during the morning of the third day. These proceedings are a simple collection of the viewgraphs used as submitted to a member of the LANL secretarial staff by speakers.

  1. A workshop on enhanced national capability for neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Hurd, Alan J [Los Alamos National Laboratory; Rhyne, James J [Los Alamos National Laboratory; Lewis, Paul S [Los Alamos National Laboratory

    2009-01-01

    This two-day workshop will engage the international neutron scattering community to vet and improve the Lujan Center Strategic Plan 2007-2013 (SP07). Sponsored by the LANL SC Program Office and the University of California, the workshop will be hosted by LANSCE Professor Sunny Sinha (UCSD). Endorsement by the Spallation Neutron Source will be requested. The discussion will focus on the role that the Lujan Center will play in the national neutron scattering landscape assuming full utilization of beamlines, a refurbished LANSCE, and a 1.4-MW SNS. Because the Lujan Strategic Plan is intended to set the stage for the Signature Facility era at LANSCE, there will be some discussion of the long-pulse spallation source at Los Alamos. Breakout groups will cover several new instrument concepts, upgrades to present instruments, expanded sample environment capabilities, and a look to the future. The workshop is in keeping with a request by BES to update the Lujan strategic plan in coordination with the SNS and the broader neutron community. Workshop invitees will be drawn from the LANSCE User Group and a broad cross section of the US, European, and Pacific Rim neutron scattering research communities.

  2. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  3. High-energy Few-cycle Pulses Directly Generated from Strongly Phase-mismatched Lithium Niobate Crystal

    DEFF Research Database (Denmark)

    Zhou, Binbin; Chong, A.; Wise, F.W.;

    2012-01-01

    We show that effective soliton compression can be realized in strongly phase-mismatched quadratic media. Sub-15 fs pulses are experimentally generated directly from 10-mm-long bulk lithium niobate crystal by 120-fs input pulses at 1300 nm.......We show that effective soliton compression can be realized in strongly phase-mismatched quadratic media. Sub-15 fs pulses are experimentally generated directly from 10-mm-long bulk lithium niobate crystal by 120-fs input pulses at 1300 nm....

  4. Micro pulse lidar

    Science.gov (United States)

    Spinhirne, James D.

    1993-01-01

    An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering has been demonstrated. The transmitter of the micropulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited by optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that systems built on the micropulse lidar concept are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

  5. PCNN-Based Image Fusion in Compressed Domain

    Directory of Open Access Journals (Sweden)

    Yang Chen

    2015-01-01

    Full Text Available This paper addresses a novel method of image fusion problem for different application scenarios, employing compressive sensing (CS as the image sparse representation method and pulse-coupled neural network (PCNN as the fusion rule. Firstly, source images are compressed through scrambled block Hadamard ensemble (SBHE for its compression capability and computational simplicity on the sensor side. Local standard variance is input to motivate PCNN and coefficients with large firing times are selected as the fusion coefficients in compressed domain. Fusion coefficients are smoothed by sliding window in order to avoid blocking effect. Experimental results demonstrate that the proposed fusion method outperforms other fusion methods in compressed domain and is effective and adaptive in different image fusion applications.

  6. Compression Ratio Adjuster

    Science.gov (United States)

    Akkerman, J. W.

    1982-01-01

    New mechanism alters compression ratio of internal-combustion engine according to load so that engine operates at top fuel efficiency. Ordinary gasoline, diesel and gas engines with their fixed compression ratios are inefficient at partial load and at low-speed full load. Mechanism ensures engines operate as efficiently under these conditions as they do at highload and high speed.

  7. Spectral Animation Compression

    Institute of Scientific and Technical Information of China (English)

    Chao Wang; Yang Liu; Xiaohu Guo; Zichun Zhong; Binh Le; Zhigang Deng

    2015-01-01

    This paper presents a spectral approach to compress dynamic animation consisting of a sequence of homeomor-phic manifold meshes. Our new approach directly compresses the field of deformation gradient defined on the surface mesh, by decomposing it into rigid-body motion (rotation) and non-rigid-body deformation (stretching) through polar decompo-sition. It is known that the rotation group has the algebraic topology of 3D ring, which is different from other operations like stretching. Thus we compress these two groups separately, by using Manifold Harmonics Transform to drop out their high-frequency details. Our experimental result shows that the proposed method achieves a good balance between the reconstruction quality and the compression ratio. We compare our results quantitatively with other existing approaches on animation compression, using standard measurement criteria.

  8. Skills Labs: workshop EMERGO toolkit

    NARCIS (Netherlands)

    Kurvers, Hub; Slootmaker, Aad

    2009-01-01

    Kurvers, H. J., & Slootmaker, A. (2009). Skills Labs: workshop EMERGO toolkit. Presentation given at project members of Skills Labs. March, 31, 2009 and April, 24, 2009, Heerlen, The Netherlands: Open University of the Netherlands.

  9. Women in Astronomy Workshop Report

    CERN Document Server

    Brough, Sarah; Brooks, Kate; Hopkins, Andrew; Maddison, Sarah

    2011-01-01

    Here we report on the Women in Astronomy Workshop (http://asawomeninastronomy.org/meetings/wia2011/), which was held on 13 May 2011 in Sydney, Australia. The workshop was organised by the Astronomical Society of Australia's Chapter on Women in Astronomy, to discuss some of the issues that face women in astronomy and make recommendations to help support the success of women in Australian astronomy but came to broader conclusions that have value for the whole astronomical community. The workshop consisted of four sessions, with presentations by invited speakers on demographics, leadership, varied career paths, and how institutions & individuals can help. The workshop ended with a discussion panel that summarised the day's debate and presented a list of recommendations for the Australian astronomical community (both individuals and institutions) that are provided in this report.

  10. The Center for the Holographic Arts Begins a New Artist Workshop and Residency Program in Conjunction with Ohio State University

    Science.gov (United States)

    Mrongovius, Martina; Kagan, Harris; Moree, Sam

    2013-02-01

    This year the Center for the Holographic Arts (Holocenter) kicked off a new Artist Workshop and Residency Program in conjunction with Ohio State University. The newly renovated holography facility houses the Holocenter's pulse laser camera and two recording tables with continuous wave lasers. This facility is being utilized for undergraduate and postgraduate courses in Art and Technology as well as the Artist Workshop and Residency Program.

  11. 6th International Microbeam Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Dr Kevin M. Prise

    2004-01-01

    The extended abstracts which are submitted here present a summary of the proceedings of the 6th International Workshop/12th LH Gray Workshop: Microbeam Probes of Cellular Radiation Response, held at St. Catherine's College, University of Oxford, UK on March, 29th-31st, 2003. In 1993 the 4th LH Gray Workshop entitled ''Microbeam Probes of Cellular Radiation Response'' was held at the Gray Cancer Institute in Northwood. This was organized by Prof BD Michael, Dr M. Folkard and Dr KM Prise and brought together 40 participants interested in developing and applying new microbeam technology to problems in radiation biology (1). The workshop was an undoubted success and has spawned a series of subsequent workshops every two years. In the past, these workshops have been highly successful in bringing together groups interested in developing and applying micro-irradiation techniques to the study of cell and tissue damage by ionizing radiations. Following the first microbeam workshop, there has been a rapid growth in the number of centres developing radiobiology microbeams, or planning to do so and there are currently 15-20 worldwide. Much of the recent research using microbeams has used them to study low-dose effects and ''non-targeted'' responses such bystander effects, genomic instability and adaptive responses. The goal of the 6th workshop was to build on our knowledge of the development of microbeam approaches and the application to radiation biology in the future with the meeting stretching over a 3 day period. Over 80 participants reviewed the current state of radiobiology microbeam research worldwide and reported on new technological developments both in the fields of physics and biology.

  12. IFPA meeting 2008 workshops report

    DEFF Research Database (Denmark)

    Lash, G.E.; Ansari, T.; Bischof, P.

    2009-01-01

    Workshops are an important part of the IFPA annual meeting. At the IFPA meeting 2008 diverse topics were discussed in 12 themed workshops. Topics covered included: immunology of placentation; galectins and trophoblast invasion; signaling in implantation and invasion; markers to identify trophoblast...... subpopulations; placental pathology; placental toxicology; sterology; placental transport of fatty acids; placental mesenchymal stem cells; comparative placentation; trophoblst and neoplasia; trophoblast differentiation. This report is a summary of the various topics covered....

  13. Data fusion and data compression research in the space sciences - An overview of selected NASA investigations

    Science.gov (United States)

    Mucklow, Glenn; Tilton, James C.; Manohar, M.

    1992-01-01

    An overview of selected research tasks representative of work being conducted in universities, industry and at NASA centers under NASA sponsorship is given. A summary is given of the papers presented at the Space and Earth Science Data Compression Workshop held in Snowbird, Utah on March 27, 1992.

  14. Theoretical models for describing longitudinal bunch compression in the neutralized drift compression experiment

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2006-09-01

    Full Text Available Heavy ion drivers for warm dense matter and heavy ion fusion applications use intense charge bunches which must undergo transverse and longitudinal compression in order to meet the requisite high current densities and short pulse durations desired at the target. The neutralized drift compression experiment (NDCX at the Lawrence Berkeley National Laboratory is used to study the longitudinal neutralized drift compression of a space-charge-dominated ion beam, which occurs due to an imposed longitudinal velocity tilt and subsequent neutralization of the beam’s space charge by background plasma. Reduced theoretical models have been used in order to describe the realistic propagation of an intense charge bunch through the NDCX device. A warm-fluid model is presented as a tractable computational tool for investigating the nonideal effects associated with the experimental acceleration gap geometry and voltage waveform of the induction module, which acts as a means to pulse shape both the velocity and line density profiles. Self-similar drift compression solutions can be realized in order to transversely focus the entire charge bunch to the same focal plane in upcoming simultaneous transverse and longitudinal focusing experiments. A kinetic formalism based on the Vlasov equation has been employed in order to show that the peaks in the experimental current profiles are a result of the fact that only the central portion of the beam contributes effectively to the main compressed pulse. Significant portions of the charge bunch reside in the nonlinearly compressing part of the ion beam because of deviations between the experimental and ideal velocity tilts. Those regions form a pedestal of current around the central peak, thereby decreasing the amount of achievable longitudinal compression and increasing the pulse durations achieved at the focal plane. A hybrid fluid-Vlasov model which retains the advantages of both the fluid and kinetic approaches has been

  15. HG2006 Workshop on High-Gradient Radio Frequency

    CERN Multimedia

    2006-01-01

    Meeting to be held at CERN on 25-27 September 2006 in Room 40/S2-B01 (Building 40). The objective of the workshop is to bring the high-gradient RF community together to present and discuss recent theoretical and experimental developments. Significant progress has recently been made in understanding the basic physics of rf breakdown and developing techniques for achieving higher gradients. This workshop should contribute to maintaining these efforts and to promoting contacts and collaboration. The scientific programme will be organized in half day sessions dedicated to: High-gradient rf experimental results Theory and computation High-gradient technology, materials and processing Specialized experiments on related high-gradient or high-power phenomenon like dc discharge and pulsed surface heating Reports from collaborations and projects. Each session will consist of selected presentations followed by a dedicated discussion. Information about the meeting and participant registration is available at http...

  16. Sub-nanosecond strong pulse generated by backward Raman scattering

    Institute of Scientific and Technical Information of China (English)

    Zhenhuan Ye(叶震寰); Qihong Lou(楼祺洪); Jingxing Dong(董景星); Yunrong Wei(魏运荣); Lei Ling(凌磊)

    2003-01-01

    Hundreds picosecond strong short-wavelength pulses have been generated by a backward Raman oscillatoramplifier pumped with a 10-J KrF laser from Heaven-1 MOPA system. Not only high power but also highenergy laser pulses have been obtained with an energy conversion efficiency up to 17%. 640-picosecondpulse duration was observed in our experiments by a 1.5-GHz-bandwidth oscilloscope corresponding to 34times of pulse compression rate.

  17. Single-grating laser pulse stretcher and compressor.

    Science.gov (United States)

    Lai, M; Lai, S T; Swinger, C

    1994-10-20

    Stretching and compressing of laser pulses is demonstrated with a single-grating apparatus. A laser pulse of 110 fs is stretched to 250 ps and then recompressed to 115 fs. The apparatus exploits a two-level structure: one level for stretching and the other for compressing. This single-grating configuration shows significant simplification in structure and alignment over existing multiple-grating systems. Such a stretcher-compressor is particularly suitable for use with chirped-pulse amplification in which laser wavelength tuning is desirable. Only one rotational adjustment is rquired to restore the alignment of the entire stretcher and compressor when the laser wavelength is changed.

  18. Displaying radiologic images on personal computers: image storage and compression--Part 2.

    Science.gov (United States)

    Gillespy, T; Rowberg, A H

    1994-02-01

    This is part 2 of our article on image storage and compression, the third article of our series for radiologists and imaging scientists on displaying, manipulating, and analyzing radiologic images on personal computers. Image compression is classified as lossless (nondestructive) or lossy (destructive). Common lossless compression algorithms include variable-length bit codes (Huffman codes and variants), dictionary-based compression (Lempel-Ziv variants), and arithmetic coding. Huffman codes and the Lempel-Ziv-Welch (LZW) algorithm are commonly used for image compression. All of these compression methods are enhanced if the image has been transformed into a differential image based on a differential pulse-code modulation (DPCM) algorithm. The LZW compression after the DPCM image transformation performed the best on our example images, and performed almost as well as the best of the three commercial compression programs tested. Lossy compression techniques are capable of much higher data compression, but reduced image quality and compression artifacts may be noticeable. Lossy compression is comprised of three steps: transformation, quantization, and coding. Two commonly used transformation methods are the discrete cosine transformation and discrete wavelet transformation. In both methods, most of the image information is contained in a relatively few of the transformation coefficients. The quantization step reduces many of the lower order coefficients to 0, which greatly improves the efficiency of the coding (compression) step. In fractal-based image compression, image patterns are stored as equations that can be reconstructed at different levels of resolution.

  19. Vascular compression syndromes.

    Science.gov (United States)

    Czihal, Michael; Banafsche, Ramin; Hoffmann, Ulrich; Koeppel, Thomas

    2015-11-01

    Dealing with vascular compression syndromes is one of the most challenging tasks in Vascular Medicine practice. This heterogeneous group of disorders is characterised by external compression of primarily healthy arteries and/or veins as well as accompanying nerval structures, carrying the risk of subsequent structural vessel wall and nerve damage. Vascular compression syndromes may severely impair health-related quality of life in affected individuals who are typically young and otherwise healthy. The diagnostic approach has not been standardised for any of the vascular compression syndromes. Moreover, some degree of positional external compression of blood vessels such as the subclavian and popliteal vessels or the celiac trunk can be found in a significant proportion of healthy individuals. This implies important difficulties in differentiating physiological from pathological findings of clinical examination and diagnostic imaging with provocative manoeuvres. The level of evidence on which treatment decisions regarding surgical decompression with or without revascularisation can be relied on is generally poor, mostly coming from retrospective single centre studies. Proper patient selection is critical in order to avoid overtreatment in patients without a clear association between vascular compression and clinical symptoms. With a focus on the thoracic outlet-syndrome, the median arcuate ligament syndrome and the popliteal entrapment syndrome, the present article gives a selective literature review on compression syndromes from an interdisciplinary vascular point of view.

  20. Critical Data Compression

    CERN Document Server

    Scoville, John

    2011-01-01

    A new approach to data compression is developed and applied to multimedia content. This method separates messages into components suitable for both lossless coding and 'lossy' or statistical coding techniques, compressing complex objects by separately encoding signals and noise. This is demonstrated by compressing the most significant bits of data exactly, since they are typically redundant and compressible, and either fitting a maximally likely noise function to the residual bits or compressing them using lossy methods. Upon decompression, the significant bits are decoded and added to a noise function, whether sampled from a noise model or decompressed from a lossy code. This results in compressed data similar to the original. For many test images, a two-part image code using JPEG2000 for lossy coding and PAQ8l for lossless coding produces less mean-squared error than an equal length of JPEG2000. Computer-generated images typically compress better using this method than through direct lossy coding, as do man...

  1. Photonics Explorer Workshop

    Science.gov (United States)

    Prasad, Amrita; Debaes, Nathalie

    2014-07-01

    The Photonics Explorer is an intra-curricular educational kit developed in a European project with a pan-European collaboration of over 35 teachers and science education professors. Unlike conventional educational outreach kits, the Photonics Explorer is specifically designed to integrate seamlessly in school curricula and enhance and complement the teaching and learning of science and optics in the classroom. The kit equips teachers with class sets of experimental components, provided within a supporting didactic framework and is designed for lower and upper secondary students (12-18 years). The kit is provided completely free of charge to teachers in conjunction with teacher training courses. The workshop will provide an overview of the Photonics Explorer intra-curricular kit and give teachers the opportunity to work hands-on with the material and didactic content of two modules, `Light Signals' (lower secondary) and `Diffraction and Interference'(upper secondary). We also aim to receive feedback regarding the content, components and didactic framework from teachers from non- European countries, to understand the relevance of the kit for their teaching and the ability for such a kit to integrate into non-EU curricula.

  2. Geomagnetic Workshop, Canberra

    Science.gov (United States)

    Barton, C. E.; Lilley, F. E. M.; Milligan, P. R.

    On May 14-15, 1985, 63 discerning geomagnetists flocked to Canberra to attend the Geomagnetic Workshop coorganized by the Australian Bureau of Mineral Resources (BMR) and the Research School of Earth Sciences, Australian National University (ANU). With an aurorally glowing cast that included an International Association of Geomagnetism and Aeronomy (IAGA) president, former president, and division chairman, the Oriental Magneto-Banquet (which was the center of the meeting), was assured of success. As a cunning ploy to mask the true nature of this gastronomic extravagance from the probings of income tax departments, a presentation of scientific papers on Australian geomagnetism in its global setting was arranged.The Australian region, including New Zealand, Papua New Guinea, Indonesia, and a large sector of the Antarctic, covers one eighth of the Earth's surface and historically has played an important role in the study of geomagnetism. The region contains both the south magnetic and geomagnetic poles, and two Australian Antarctic stations (Casey and Davis) are situated in the region of the south polar cusp (see Figure 1).

  3. Photovoltaic module reliability workshop

    Energy Technology Data Exchange (ETDEWEB)

    Mrig, L. (ed.)

    1990-01-01

    The paper and presentations compiled in this volume form the Proceedings of the fourth in a series of Workshops sponsored by Solar Energy Research Institute (SERI/DOE) under the general theme of photovoltaic module reliability during the period 1986--1990. The reliability Photo Voltaic (PV) modules/systems is exceedingly important along with the initial cost and efficiency of modules if the PV technology has to make a major impact in the power generation market, and for it to compete with the conventional electricity producing technologies. The reliability of photovoltaic modules has progressed significantly in the last few years as evidenced by warranties available on commercial modules of as long as 12 years. However, there is still need for substantial research and testing required to improve module field reliability to levels of 30 years or more. Several small groups of researchers are involved in this research, development, and monitoring activity around the world. In the US, PV manufacturers, DOE laboratories, electric utilities and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in this field were brought together under SERI/DOE sponsorship to exchange the technical knowledge and field experience as related to current information in this important field. The papers presented here reflect this effort.

  4. VLLEEM-2 technical workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    In order to overcome the limits of the energy-environment models, and to benefit at the same time of their past experiences, the VLEEM project proposes a genuine approach and innovative modelling tools to assess the energy-environment systems over the very long term, which are based on the strengths of existing long term energy models, but focussed on two major objectives: to describe normative futures which fit with a set of overall constraints, like the stabilisation of the concentration of green-house gases in the atmosphere, or the stabilisation of the overall inventory of plutonium and minor actinides, etc...; to describe and formalize the association of causalities necessary to bring the system from the present situation to the targeted future, through a '' back-casting '' approach. This first technical workshop presents the state of the art of the different Work Programmes. WP1:Enhancement of the Conceptual framework. WP2: Data base on conventional demand/supply technologies. WP3: Complement and up-date technology monographs. WP4: Formalization and computing of final VLEEM submodels. WP5: Case study 2030, 2050, 2100. (A.L.B.)

  5. Pulse compressor with aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  6. Limits to compression with cascaded quadratic soliton compressors

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    that it is theoretically possible to reach the single-cycle regime by compressing high-energy fs pulses for wavelengths λ = 1.0−1.3 μm in a β -barium-borate crystal, and it requires that the system is in the stationary regime, where the phase mismatch is large enough to overcome the detrimental GVM effects. however...

  7. Compressive sensing for high resolution profiles with enhanced Doppler performance

    NARCIS (Netherlands)

    Anitori, L.; Hoogeboom, P.; Chevalier, F. Le; Otten, M.P.G.

    2012-01-01

    In this paper we demonstrate how Compressive Sensing (CS) can be used in pulse-Doppler radars to improve the Doppler performance while preserving range resolution. We investigate here two types of stepped frequency waveforms, the coherent frequency bursts and successive frequency ramps, which can be

  8. Vortex stabilized electron beam compressed fusion grade plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch, Ady [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-03-19

    Most inertial confinement fusion schemes are comprised of highly compressed dense plasmas. Those schemes involve short, extremely high power, short pulses of beams (lasers, particles) applied to lower density plasmas or solid pellets. An alternative approach could be to shoot an intense electron beam through very dense, atmospheric pressure, vortex stabilized plasma.

  9. Pulsed thermoelectricity

    Science.gov (United States)

    Apostol, M.; Nedelcu, M.

    2010-07-01

    A special mechanism of thermoelectric transport is described, consisting of pulses of charge carriers which "fly" periodically through the external circuit from the hot end of the sample to the cold end, with a determined duration of the "on" and "off" times of the electric contacts, while maintaining continuously the thermal contacts. It is shown that such a "resonant" ideal thermogenerator may work cyclically, with the same efficiency quotient as the ideal efficiency quotient of the thermoelectric devices operated in the usual stationary transport regime but the electric flow and power are increased, as a consequence of the concentration of the charge carriers on pulses of small spatial extent. The process is reversible, in the sense that it can be operated either as a thermoelectric generator or as an electrothermal cooler.

  10. Prediction by Compression

    CERN Document Server

    Ratsaby, Joel

    2010-01-01

    It is well known that text compression can be achieved by predicting the next symbol in the stream of text data based on the history seen up to the current symbol. The better the prediction the more skewed the conditional probability distribution of the next symbol and the shorter the codeword that needs to be assigned to represent this next symbol. What about the opposite direction ? suppose we have a black box that can compress text stream. Can it be used to predict the next symbol in the stream ? We introduce a criterion based on the length of the compressed data and use it to predict the next symbol. We examine empirically the prediction error rate and its dependency on some compression parameters.

  11. LZW Data Compression

    Directory of Open Access Journals (Sweden)

    Dheemanth H N

    2016-07-01

    Full Text Available Lempel–Ziv–Welch (LZW is a universal lossless data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. LZW compression is one of the Adaptive Dictionary techniques. The dictionary is created while the data are being encoded. So encoding can be done on the fly. The dictionary need not be transmitted. Dictionary can be built up at receiving end on the fly. If the dictionary overflows then we have to reinitialize the dictionary and add a bit to each one of the code words. Choosing a large dictionary size avoids overflow, but spoils compressions. A codebook or dictionary containing the source symbols is constructed. For 8-bit monochrome images, the first 256 words of the dictionary are assigned to the gray levels 0-255. Remaining part of the dictionary is filled with sequences of the gray levels.LZW compression works best when applied on monochrome images and text files that contain repetitive text/patterns.

  12. Shocklets in compressible flows

    Institute of Scientific and Technical Information of China (English)

    袁湘江; 男俊武; 沈清; 李筠

    2013-01-01

    The mechanism of shocklets is studied theoretically and numerically for the stationary fluid, uniform compressible flow, and boundary layer flow. The conditions that trigger shock waves for sound wave, weak discontinuity, and Tollmien-Schlichting (T-S) wave in compressible flows are investigated. The relations between the three types of waves and shocklets are further analyzed and discussed. Different stages of the shocklet formation process are simulated. The results show that the three waves in compressible flows will transfer to shocklets only when the initial disturbance amplitudes are greater than the certain threshold values. In compressible boundary layers, the shocklets evolved from T-S wave exist only in a finite region near the surface instead of the whole wavefront.

  13. Reference Based Genome Compression

    CERN Document Server

    Chern, Bobbie; Manolakos, Alexandros; No, Albert; Venkat, Kartik; Weissman, Tsachy

    2012-01-01

    DNA sequencing technology has advanced to a point where storage is becoming the central bottleneck in the acquisition and mining of more data. Large amounts of data are vital for genomics research, and generic compression tools, while viable, cannot offer the same savings as approaches tuned to inherent biological properties. We propose an algorithm to compress a target genome given a known reference genome. The proposed algorithm first generates a mapping from the reference to the target genome, and then compresses this mapping with an entropy coder. As an illustration of the performance: applying our algorithm to James Watson's genome with hg18 as a reference, we are able to reduce the 2991 megabyte (MB) genome down to 6.99 MB, while Gzip compresses it to 834.8 MB.

  14. Deep Blind Compressed Sensing

    OpenAIRE

    Singh, Shikha; Singhal, Vanika; Majumdar, Angshul

    2016-01-01

    This work addresses the problem of extracting deeply learned features directly from compressive measurements. There has been no work in this area. Existing deep learning tools only give good results when applied on the full signal, that too usually after preprocessing. These techniques require the signal to be reconstructed first. In this work we show that by learning directly from the compressed domain, considerably better results can be obtained. This work extends the recently proposed fram...

  15. Reference Based Genome Compression

    OpenAIRE

    Chern, Bobbie; Ochoa, Idoia; Manolakos, Alexandros; No, Albert; Venkat, Kartik; Weissman, Tsachy

    2012-01-01

    DNA sequencing technology has advanced to a point where storage is becoming the central bottleneck in the acquisition and mining of more data. Large amounts of data are vital for genomics research, and generic compression tools, while viable, cannot offer the same savings as approaches tuned to inherent biological properties. We propose an algorithm to compress a target genome given a known reference genome. The proposed algorithm first generates a mapping from the reference to the target gen...

  16. Multi-target compressive laser ranging

    Science.gov (United States)

    Pandit, Pushkar P.; Dahl, Jason R.; Barber, Zeb W.; Babbitt, W. Randall

    2014-05-01

    Compressive laser ranging (CLR) is a method that exploits the sparsity available in the range domain using compressive sensing methods to directly obtain range domain information. Conventional ranging methods are marred by requirements of high bandwidth analog detection which includes severe SNR fall off with bandwidth in analog-to-digital conversion (ADC). Compressive laser ranging solves this problem by obtaining sub-centimeter resolution while using low bandwidth detection. High rate digital pulse pattern generators and off the shelf photonic devices are used to modulate the transmitted and received light from a superluminescent diode. CLR detection is demonstrated using low bandwidth, high dynamic range detectors along with photon counting techniques. The use of an incoherent source eliminates speckle issues and enables simplified CLR methods to get multi-target range profiles with 1-3cm resolution. Using compressive sensing methods CLR allows direct range measurements in the sub-Nyquist regime while reducing system resources, in particular the need for high bandwidth ADC.

  17. Alternative Compression Garments

    Science.gov (United States)

    Stenger, M. B.; Lee, S. M. C.; Ribeiro, L. C.; Brown, A. K.; Westby, C. M.; Platts, S. H.

    2011-01-01

    Orthostatic intolerance after spaceflight is still an issue for astronauts as no in-flight countermeasure has been 100% effective. Future anti-gravity suits (AGS) may be similar to the Shuttle era inflatable AGS or may be a mechanical compression device like the Russian Kentavr. We have evaluated the above garments as well as elastic, gradient compression garments of varying magnitude and determined that breast-high elastic compression garments may be a suitable replacement to the current AGS. This new garment should be more comfortable than the AGS, easy to don and doff, and as effective a countermeasure to orthostatic intolerance. Furthermore, these new compression garments could be worn for several days after space flight as necessary if symptoms persisted. We conducted two studies to evaluate elastic, gradient compression garments. The purpose of these studies was to evaluate the comfort and efficacy of an alternative compression garment (ACG) immediately after actual space flight and 6 degree head-down tilt bed rest as a model of space flight, and to determine if they would impact recovery if worn for up to three days after bed rest.

  18. Physics Analysis Tools Workshop Report

    CERN Document Server

    Assamagan, K A

    A Physics Analysis Tools (PAT) workshop was held at the University of Tokyo in Tokyo Japan on May 15-19, 2006. Unlike the previous ones, this workshop brought together the core PAT developers and ATLAS users. The workshop was attended by 69 people from various institutions: Australia 5 Canada 1 China 6 CERN 4 Europe 7 Japan 32 Taiwan 3 USA 11 The agenda consisted of a 2-day tutorial for users, a 0.5-day user feedback discussion session between users and developers, and a 2-day core PAT workshop devoted to issues in Physics Analysis Tools activities. The tutorial, attended by users and developers, covered the following grounds: Event Selection with the TAG Event Selection Using the Athena-Aware NTuple Event Display Interactive Analysis within ATHENA Distributed Analysis Monte Carlo Truth Tools Trigger-Aware Analysis Event View By many accounts, the tutorial was useful. This workshop was the first time that the ATLAS Asia-Pacific community (Taiwan, Japan, China and Australia) go...

  19. Multichannel Compressive Sensing MRI Using Noiselet Encoding

    CERN Document Server

    Pawar, Kamlesh; Zhang, Jingxin

    2014-01-01

    The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI, and presents a method to design the pulse sequence for the noiselet encoding. This novel encoding scheme is combined with the multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. An empirical RIP a...

  20. Mars Sample Handling Protocol Workshop Series: Workshop 4

    Science.gov (United States)

    Race Margaret S. (Editor); DeVincenzi, Donald L. (Editor); Rummel, John D. (Editor); Acevedo, Sara E. (Editor)

    2001-01-01

    In preparation for missions to Mars that will involve the return of samples to Earth, it will be necessary to prepare for the receiving, handling, testing, distributing, and archiving of martian materials here on Earth. Previous groups and committees have studied selected aspects of sample return activities, but specific detailed protocols for the handling and testing of returned samples must still be developed. To further refine the requirements for sample hazard testing and to develop the criteria for subsequent release of sample materials from quarantine, the NASA Planetary Protection Officer convened a series of workshops in 2000-2001. The overall objective of the Workshop Series was to produce a Draft Protocol by which returned martian sample materials can be assessed for biological hazards and examined for evidence of life (extant or extinct) while safeguarding the purity of the samples from possible terrestrial contamination. This report also provides a record of the proceedings of Workshop 4, the final Workshop of the Series, which was held in Arlington, Virginia, June 5-7, 2001. During Workshop 4, the sub-groups were provided with a draft of the protocol compiled in May 2001 from the work done at prior Workshops in the Series. Then eight sub-groups were formed to discuss the following assigned topics: Review and Assess the Draft Protocol for Physical/Chemical Testing Review and Assess the Draft Protocol for Life Detection Testing Review and Assess the Draft Protocol for Biohazard Testing Environmental and Health/Monitoring and Safety Issues Requirements of the Draft Protocol for Facilities and Equipment Contingency Planning for Different Outcomes of the Draft Protocol Personnel Management Considerations in Implementation of the Draft Protocol Draft Protocol Implementation Process and Update Concepts This report provides the first complete presentation of the Draft Protocol for Mars Sample Handling to meet planetary protection needs. This Draft Protocol

  1. Square pulse linear transformer driver

    Directory of Open Access Journals (Sweden)

    A. A. Kim

    2012-04-01

    Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

  2. Observation of soliton compression in silicon photonic crystals

    Science.gov (United States)

    Blanco-Redondo, A.; Husko, C.; Eades, D.; Zhang, Y.; Li, J.; Krauss, T.F.; Eggleton, B.J.

    2014-01-01

    Solitons are nonlinear waves present in diverse physical systems including plasmas, water surfaces and optics. In silicon, the presence of two photon absorption and accompanying free carriers strongly perturb the canonical dynamics of optical solitons. Here we report the first experimental demonstration of soliton-effect pulse compression of picosecond pulses in silicon, despite two photon absorption and free carriers. Here we achieve compression of 3.7 ps pulses to 1.6 ps with crystal waveguide and an ultra-sensitive frequency-resolved electrical gating technique to detect the ultralow energies in the nanostructured device. Strong agreement with a nonlinear Schrödinger model confirms the measurements. These results further our understanding of nonlinear waves in silicon and open the way to soliton-based functionalities in complementary metal-oxide-semiconductor-compatible platforms. PMID:24423977

  3. Li'l Red Schoolhouse workshops

    Science.gov (United States)

    1993-01-01

    Education specialists at Stennis conduct staff development workshops for elementary and secondary teachers of math, science and technology and other subjects as well as specialized workshops conducted in the NASA Li'l Red Schoolhouse.

  4. GLOBE Hydrology Workshop SEIP program

    Science.gov (United States)

    2005-01-01

    Matt Krigbaum (left), a teacher at Mitchell Elementary in Ann Arbor, Mich., pours water from the Pearl River into a turbidity tube to measure the river's light penetration. Krigbaum, along with Lois Williams, principal at Elizabeth Courville Elementary in Detroit, Mich.; and Carolyn Martin and Arlene Wittmer, teachers at Elizabeth Courville Elementary; conducted the experiment during a GLOBE (Global Learning and Observations to Benefit the Environment) hydrology workshop. GLOBE is a worldwide, hands-on science education program in which teachers can become certified to implement the program at their schools after taking hydrology, land cover/biology, atmosphere/climate and soil protocol workshops. Twelve teachers from across the country attended the recent weeklong GLOBE training at SSC, offered through its Educator Resource Center and the NASA Explorer Schools program. All workshops are free and offer continuing education units.

  5. Extreme Conditions Modeling Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Coe, Ryan Geoffrey [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Neary, Vincent Sinclair [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Lawon, Michael J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Lab. (NREL), Golden, CO (United States); Weber, Jochem [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2014-07-01

    Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL) hosted the Wave Energy Converter (WEC) Extreme Conditions Modeling (ECM) Workshop in Albuquerque, New Mexico on May 13–14, 2014. The objective of the workshop was to review the current state of knowledge on how to numerically and experimentally model WECs in extreme conditions (e.g. large ocean storms) and to suggest how national laboratory resources could be used to improve ECM methods for the benefit of the wave energy industry. More than 30 U.S. and European WEC experts from industry, academia, and national research institutes attended the workshop, which consisted of presentations from W EC developers, invited keynote presentations from subject matter experts, breakout sessions, and a final plenary session .

  6. H2@Scale Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Pivovar, Bryan

    2017-03-31

    Final report from the H2@Scale Workshop held November 16-17, 2016, at the National Renewable Energy Laboratory in Golden, Colorado. The U.S. Department of Energy's National Renewable Energy Laboratory hosted a technology workshop to identify the current barriers and research needs of the H2@Scale concept. H2@Scale is a concept regarding the potential for wide-scale impact of hydrogen produced from diverse domestic resources to enhance U.S. energy security and enable growth of innovative technologies and domestic industries. Feedback received from a diverse set of stakeholders at the workshop will guide the development of an H2@Scale roadmap for research, development, and early stage demonstration activities that can enable hydrogen as an energy carrier at a national scale.

  7. Cleanroom Energy Efficiency Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Tschudi, Bill

    1999-03-15

    On March 15, 1999, Lawrence Berkeley National Laboratory hosted a workshop focused on energy efficiency in Cleanroom facilities. The workshop was held as part of a multiyear effort sponsored by the California Institute for Energy Efficiency, and the California Energy Commission. It is part of a project that concentrates on improving energy efficiency in Laboratory type facilities including cleanrooms. The project targets the broad market of laboratory and cleanroom facilities, and thus cross-cuts many different industries and institutions. This workshop was intended to raise awareness by sharing case study success stories, providing a forum for industry networking on energy issues, contributing LBNL expertise in research to date, determining barriers to implementation and possible solutions, and soliciting input for further research.

  8. Midwest Transmission Workshop III Summary

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Bryan

    2003-03-12

    OAK-B135 On March 12-13, 2002, the National Wind Coordinating Committee (NWCC), in cooperation with regional stakeholders, held a two-day workshop: Planning for Electrical Transmission Needs in the Upper Midwest. The workshop was the outgrowth of an effort to develop a forum and process for consideration of transmission options that strives for equitable allocation of benefits and impacts among all affected parties. The goal of this workshop was to provide a catalyst for an enhanced, inclusive process for transmission planning with participation of and acceptance by all affected stakeholders. Participants in the meeting included representatives of state and regional regulatory agencies, utilities and power generators, the wind industry, environmental and landowner interests, and other interested parties (see Attachment A for a list of meeting participants).

  9. Workshop on the RHIC performance

    Energy Technology Data Exchange (ETDEWEB)

    Khiari, F.; Milutinovic, J.; Ratti, A.; Rhoades-Brown, M.J. (eds.)

    1988-07-01

    The most recent conceptual design manual for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven was published in May 1986 (BNL 51932). The purpose of this workshop was to review the design specifications in this RHIC reference manual, and to discuss in detail possible improvements in machine performance by addressing four main areas. These areas are beam-beam interactions, stochastic cooling, rf and bunch instabilities. The contents of this proceedings are as follows. Following an overview of the workshop, in which the motivation and goals are discussed in detail, transcripts of the first day talks are given. Many of these transcripts are copies of the original transparencies presented at the meeting. The following four sections contain contributed papers, that resulted from discussions at the workshop within each of the four working groups. In addition, there is a group summary for each of the four working groups at the beginning of each section. Finally, a list of participants is given.

  10. Photovoltaic performance and reliability workshop

    Energy Technology Data Exchange (ETDEWEB)

    Mrig, L. [ed.

    1993-12-01

    This workshop was the sixth in a series of workshops sponsored by NREL/DOE under the general subject of photovoltaic testing and reliability during the period 1986--1993. PV performance and PV reliability are at least as important as PV cost, if not more. In the US, PV manufacturers, DOE laboratories, electric utilities, and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in the field were brought together to exchange the technical knowledge and field experience as related to current information in this evolving field of PV reliability. The papers presented here reflect this effort since the last workshop held in September, 1992. The topics covered include: cell and module characterization, module and system testing, durability and reliability, system field experience, and standards and codes.

  11. Reports of the AAAI 2010 Conference Workshops

    OpenAIRE

    2010-01-01

    The AAAI-10 Workshop program was held Sunday and Monday, July 11–12, 2010 at the Westin Peachtree Plaza in Atlanta, Georgia. The AAAI-10 workshop program included 13 workshops covering a wide range of topics in artificial intelligence. The titles of the workshops were AI and Fun, Bridging the Gap between Task and Motion Planning, Collaboratively-Built Knowledge Sources and Artificial Intelligence, Goal-Directed Autonomy, Intelligent Security, Interactive Decision Theory and Game Theory,...

  12. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  13. SEED BANKS FOR MAGNETIC FLUX COMPRESSION GENERATORS

    Energy Technology Data Exchange (ETDEWEB)

    Fulkerson, E S

    2008-05-14

    In recent years the Lawrence Livermore National Laboratory (LLNL) has been conducting experiments that require pulsed high currents to be delivered into inductive loads. The loads fall into two categories (1) pulsed high field magnets and (2) the input stage of Magnetic Flux Compression Generators (MFCG). Three capacitor banks of increasing energy storage and controls sophistication have been designed and constructed to drive these loads. One bank was developed for the magnet driving application (20kV {approx} 30kJ maximum stored energy.) Two banks where constructed as MFCG seed banks (12kV {approx} 43kJ and 26kV {approx} 450kJ). This paper will describe the design of each bank including switching, controls, circuit protection and safety.

  14. Extreme Conditions Modeling Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Coe, R. G.; Neary, V. S.; Lawson, M. J.; Yu, Y.; Weber, J.

    2014-07-01

    Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL) hosted the Wave Energy Converter (WEC) Extreme Conditions Modeling (ECM) Workshop in Albuquerque, NM on May 13th-14th, 2014. The objective of the workshop was to review the current state of knowledge on how to model WECs in extreme conditions (e.g. hurricanes and other large storms) and to suggest how U.S. Department of Energy (DOE) and national laboratory resources could be used to improve ECM methods for the benefit of the wave energy industry.

  15. 1993 Radiation Protection Workshop: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-31

    The 1993 DOE Radiation Protection Workshop was conducted from April 13 through 15, 1993 in Las Vegas, Nevada. Over 400 Department of Energy Headquarters and Field personnel and contractors from the DOE radiological protection community attended the Workshop. Forty-nine papers were presented in eleven separate sessions: Radiological Control Manual Implementation, New Approaches to Instrumentation and Calibration, Radiological Training Programs and Initiatives, External Dosimetry, Internal Dosimetry, Radiation Exposure Reporting and Recordkeeping, Air Sampling and Monitoring Issues, Decontamination and Decommissioning of Sites, Contamination Monitoring and Control, ALARA/Radiological Engineering, and Current and Future Health Physics Research. Individual papers are indexed separately on the database.

  16. Physics beyond Colliders Kickoff Workshop

    CERN Document Server

    2016-01-01

    The aim of the workshop is to explore the opportunities offered by the CERN accelerator complex and infrastructure to get new insights into some of today's outstanding questions in particle physics through projects complementary to high-energy colliders and other initiatives in the world. The focus is on fundamental physics questions that are similar in spirit to those addressed by high-energy colliders, but that may require different types of experiments. The kickoff workshop is intended to stimulate new ideas for such projects, for which we encourage the submission of abstracts.

  17. Workshop on Physics Beyond Colliders

    CERN Document Server

    2016-01-01

    The aim of the workshop is to explore the opportunities offered by the CERN accelerator complex and infrastructure to get new insights into some of today's outstanding questions in particle physics through projects complementary to high-energy colliders and other initiatives in the world. The focus is on fundamental physics questions that are similar in spirit to those addressed by high-energy colliders, but that may require different types of experiments. The kick-off workshop is intended to stimulate new ideas for such projects, for which we encourage the submission of abstracts.

  18. Mutual Workshops enhancing Curriculum Integration

    DEFF Research Database (Denmark)

    Bjerregaard Jensen, Lotte; Markvorsen, Steen; Almegaard, Henrik

    2011-01-01

    -semester project in structural design was realized for the first time in autumn 2009. This paper presents the lessons learned from this first round along with the changes they inspired. Amongst the biggest changes made was the introduction of a successful joint workshop between the geometry course and the design...... course. This realized the full potential of structural design and firmly highlighted the creative potential in geometry for hesitant students. The joint workshop also showed potential as a general tool that can enhance curriculum integration....

  19. Workshop on momentum distributions: Summary

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, R.O.

    1988-01-01

    This has been an extraordinary Workshop touching many branches of physics. The Workshop has treated momentum distributions in fluid and solid condensed matter, in nuclei, and in electronic systems. Both theoretical and experimental concepts and methods have been considered in all these branches. A variety of specific illustrations and applications in physical systems have been presented. One finds that some common unifying themes emerge. One finds, also, that some examples are available to illustrate where one branch is more mature than others and to contrast where expectations for future progress may be most encouraged. 6 refs., 2 figs.

  20. IFAN Workshop Held in Beijing

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ IFAN, International Federation of Standards Users, was pleased to held its workshop on "Application of Standards in China and Beyond" connected with its annual members' assembly meeting on 25~26 October, 2006 in Beijing. The objective of the workshop is to use the opportunity of being in China to achieve a deeper level of understanding of Chinese and non-Chinese standards; to exchange views and information on the application of standards (Benefits and Challenges); and to study more profoundly the standardization and technical regulation system in China.

  1. EVALUATION OF REGISTRATION, COMPRESSION AND CLASSIFICATION ALGORITHMS

    Science.gov (United States)

    Jayroe, R. R.

    1994-01-01

    Several types of algorithms are generally used to process digital imagery such as Landsat data. The most commonly used algorithms perform the task of registration, compression, and classification. Because there are different techniques available for performing registration, compression, and classification, imagery data users need a rationale for selecting a particular approach to meet their particular needs. This collection of registration, compression, and classification algorithms was developed so that different approaches could be evaluated and the best approach for a particular application determined. Routines are included for six registration algorithms, six compression algorithms, and two classification algorithms. The package also includes routines for evaluating the effects of processing on the image data. This collection of routines should be useful to anyone using or developing image processing software. Registration of image data involves the geometrical alteration of the imagery. Registration routines available in the evaluation package include image magnification, mapping functions, partitioning, map overlay, and data interpolation. The compression of image data involves reducing the volume of data needed for a given image. Compression routines available in the package include adaptive differential pulse code modulation, two-dimensional transforms, clustering, vector reduction, and picture segmentation. Classification of image data involves analyzing the uncompressed or compressed image data to produce inventories and maps of areas of similar spectral properties within a scene. The classification routines available include a sequential linear technique and a maximum likelihood technique. The choice of the appropriate evaluation criteria is quite important in evaluating the image processing functions. The user is therefore given a choice of evaluation criteria with which to investigate the available image processing functions. All of the available

  2. Iterative methods for compressible Navier-Stokes and Euler equations

    Energy Technology Data Exchange (ETDEWEB)

    Tang, W.P.; Forsyth, P.A.

    1996-12-31

    This workshop will focus on methods for solution of compressible Navier-Stokes and Euler equations. In particular, attention will be focused on the interaction between the methods used to solve the non-linear algebraic equations (e.g. full Newton or first order Jacobian) and the resulting large sparse systems. Various types of block and incomplete LU factorization will be discussed, as well as stability issues, and the use of Newton-Krylov methods. These techniques will be demonstrated on a variety of model transonic and supersonic airfoil problems. Applications to industrial CFD problems will also be presented. Experience with the use of C++ for solution of large scale problems will also be discussed. The format for this workshop will be four fifteen minute talks, followed by a roundtable discussion.

  3. Architecture-Centric Virtual Integration Workshop

    Science.gov (United States)

    2014-09-29

    Filali 0530-0600 - Workshop Discussion: future directions for architecture -centric research efforts? - Conclusion and Follow-Up - Moderator ...2014 Carnegie Mellon University Architecture -Centric Virtual Integration Workshop Software Engineering Institute Carnegie Mellon University...SUBTITLE Architecture -Centric Virtual Integration Workshop 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Julien

  4. Development of a Workshop Evaluation Instrument.

    Science.gov (United States)

    Johnson, William L.; Wiens, Scott A.; Johnson, Annabel M.

    This paper details the development and psychometric analysis of an instrument used for workshop evaluation. The instrument was designed to assess the effectiveness of the workshops, the instructors conducting the workshop training, and the training materials. The instrument used a Likert agree/disagree format. A psychometric analysis of scores…

  5. IFPA meeting 2010 workshop report I

    DEFF Research Database (Denmark)

    Abad, C.; Antczak, D.F.; Carvalho, J.

    2011-01-01

    Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 there were twelve themed workshops, six of which are summarized in this report. 1. The immunology workshop focused on normal and pathological functions of the maternal immune system in pregnancy. 2. The transport wor...

  6. IFPA Meeting 2013 Workshop Report II

    DEFF Research Database (Denmark)

    Ackerman, W E; Adamson, L; Carter, Anthony Michael

    2013-01-01

    Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At the IFPA meeting 2013 twelve themed workshops were presented, five of which are summarized in this report. These workshops related to various aspects of placental biology...

  7. IFPA Meeting 2011 workshop report II

    DEFF Research Database (Denmark)

    Bulmer, J N; Burton, G J; Collins, S

    2012-01-01

    Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, three of which are summarized in this report. These workshops related to vascular systems and circulation in the mother, placenta...

  8. Conducting workshops in a busy clinical environment

    DEFF Research Database (Denmark)

    Brandrup, Morten; Østergaard, Kija Lin

    the workshop activity into shorter workshop "sprints" with a small number of participants for each sprint. The repetition of workshop sprints is done iteratively in the sense that every output of a sprint is transferred to the next sprint as a collective accumulative memory....

  9. IFPA meeting 2012 workshop report I

    DEFF Research Database (Denmark)

    Ackerman, W E; Carter, Anthony Michael; De Mestre, A M

    2013-01-01

    Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2012 there were twelve themed workshops, three of which are summarized in this report. These workshops related to various aspects of placental biology but collectively co...

  10. Field mapping of ballistic pressure pulse sources

    Directory of Open Access Journals (Sweden)

    Rad Abtin Jamshidi

    2015-09-01

    Full Text Available Ballistic pressure pulse sources are used since late 1990s for the extracorporeal treatment of chronic Enthesitis. Newly indications are found in trigger-point-therapy for the treatment of musculoskeletal disorders. In both applications excellent results without relevant side effects were found in clinical trials. The technical principle of pressure pulse source is based on the same techniques used in air guns. A projectile is accelerated by pressurized air and hits the applicator with high kinetic energy. By this a compression wave travels through the material and induces a fast (4..5μs, almost singular pressure pulse of 2..10 MPa, which is followed by an equally short rarefaction phase of about the same amplitude. It is assumed that the pressure pulse accounts for the biomedical effects of the device. The slower inertial motion of the waveguide is damped by elastic stoppers, but still can be measured several micro seconds after the initial pressure pulse. In order to characterize the pressure pulse devices, field mapping is performed on several radial pressure pulse sources using the fiber optic hydrophone and a polyvinylidenfluorid (PVDF piezoelectric hydrophone. It could be shown that the current standard (IEC 61846 is not appropriate for characterization of ballistic pressure pulse sources.

  11. Electromagnetic ion cyclotron waves stimulated by modest magnetospheric compressions

    Science.gov (United States)

    Anderson, B. J.; Hamilton, D. C.

    1993-01-01

    AMPTE/CCE magnetic field and particle data are used to test the suggestion that increased hot proton temperature anisotropy resulting from convection during magnetospheric compression is responsible for the enhancement in Pc 1 emission via generation of electromagnetic ion cyclotron (EMIC) waves in the dayside outer equatorial magnetosphere. The relative increase in magnetic field is used to gauge the strength of the compression, and an image dipole model is used to estimate the motion of the plasma during compression. Proton data are used to analyze the evolution of the proton distribution and the corresponding changes in EMIC wave activity expected during the compression. It is suggested that enhancements in dynamic pressure pump the energetic proton distributions in the outer magnetosphere, driving EMIC waves. Waves are expected to be generated most readily close to the magnetopause, and transient pressure pulses may be associated with bursts of EMIC waves, which would be observed on the ground in association with ionospheric transient signatures.

  12. Asteroid Generated Tsunami Workshop: Summary of NASA/NOAA Workshop

    Science.gov (United States)

    Morrison, David; Venkatapathy, Ethiraj

    2017-01-01

    A two-day workshop on tsunami generated by asteroid impacts in the ocean resulted in a broad consensus that the asteroid impact tsunami threat is not as great as previously thought, that airburst events in particular are unlikely to produce significant damage by tsunami, and that the tsunami contribution to the global ensemble impact hazard is substantially less than the contribution from land impacts. The workshop, led by Ethiraj Venkatapathy and David Morrison of NASA Ames, was organized into three sessions: 1) Near-field wave generation by the impact; 2) Long distance wave propagation; 3) Damage from coastal run-up and inundation, and associated hazard. Workshop approaches were to compare simulations to understand differences in the results and gain confidence in the modeling for both formation and propagation of tsunami from asteroid impacts, and to use this information for preliminary global risk assessment. The workshop focus was on smaller asteroids (diameter less than 250m), which represent the most frequent impacts.

  13. Transverse Compression of Tendons.

    Science.gov (United States)

    Salisbury, S T Samuel; Buckley, C Paul; Zavatsky, Amy B

    2016-04-01

    A study was made of the deformation of tendons when compressed transverse to the fiber-aligned axis. Bovine digital extensor tendons were compression tested between flat rigid plates. The methods included: in situ image-based measurement of tendon cross-sectional shapes, after preconditioning but immediately prior to testing; multiple constant-load creep/recovery tests applied to each tendon at increasing loads; and measurements of the resulting tendon displacements in both transverse directions. In these tests, friction resisted axial stretch of the tendon during compression, giving approximately plane-strain conditions. This, together with the assumption of a form of anisotropic hyperelastic constitutive model proposed previously for tendon, justified modeling the isochronal response of tendon as that of an isotropic, slightly compressible, neo-Hookean solid. Inverse analysis, using finite-element (FE) simulations of the experiments and 10 s isochronal creep displacement data, gave values for Young's modulus and Poisson's ratio of this solid of 0.31 MPa and 0.49, respectively, for an idealized tendon shape and averaged data for all the tendons and E = 0.14 and 0.10 MPa for two specific tendons using their actual measured geometry. The compression load versus displacement curves, as measured and as simulated, showed varying degrees of stiffening with increasing load. This can be attributed mostly to geometrical changes in tendon cross section under load, varying according to the initial 3D shape of the tendon.

  14. Reliability of using nondestructive tests to estimate compressive strength of building stones and bricks

    Directory of Open Access Journals (Sweden)

    Ali Abd Elhakam Aliabdo

    2012-09-01

    Full Text Available This study aims to investigate the relationships between Schmidt hardness rebound number (RN and ultrasonic pulse velocity (UPV versus compressive strength (fc of stones and bricks. Four types of rocks (marble, pink lime stone, white lime stone and basalt and two types of burned bricks and lime-sand bricks were studied. Linear and non-linear models were proposed. High correlations were found between RN and UPV versus compressive strength. Validation of proposed models was assessed using other specimens for each material. Linear models for each material showed good correlations than non-linear models. General model between RN and compressive strength of tested stones and bricks showed a high correlation with regression coefficient R2 value of 0.94. Estimation of compressive strength for the studied stones and bricks using their rebound number and ultrasonic pulse velocity in a combined method was generally more reliable than using rebound number or ultrasonic pulse velocity only.

  15. Mechanism study of hollow-core fiber infrared-supercontinuum compression with bulk material

    OpenAIRE

    2010-01-01

    International audience; We numerically investigate the pulse compression mechanism in the infrared spectral range based on the successive action of nonlinear pulse propagation in a hollow-core fiber (HCF) followed by linear propagation through bulk material. We found an excellent agreement of simulated pulse properties with experimental results at 1.8 µm in the two optical-cycle regime close to the Fourier limit (FL). In particular, the spectral phase asymmetry attributable to self-steepening ...

  16. Enhanced nonlinear spectral compression in fiber by external sinusoidal phase modulation

    Science.gov (United States)

    Boscolo, S.; Mouradian, L. Kh; Finot, C.

    2016-10-01

    We propose a new, simple approach to enhance the spectral compression process arising from nonlinear pulse propagation in an optical fiber. We numerically show that an additional sinusoidal temporal phase modulation of the pulse enables efficient reduction of the intensity level of the side lobes in the spectrum that are produced by the mismatch between the initial linear negative chirp of the pulse and the self-phase modulation-induced nonlinear positive chirp. Remarkable increase of both the extent of spectrum narrowing and the quality of the compressed spectrum is afforded by the proposed approach across a wide range of experimentally accessible parameters.

  17. SYMBOLIC VERSOR COMPRESSION ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Li Hongbo

    2009-01-01

    In an inner-product space, an invertible vector generates a reflection with re-spect to a hyperplane, and the Clifford product of several invertible vectors, called a versor in Clifford algebra, generates the composition of the corresponding reflections, which is an orthogonal transformation. Given a versor in a Clifford algebra, finding another sequence of invertible vectors of strictly shorter length but whose Clifford product still equals the input versor, is called versor compression. Geometrically, versor compression is equivalent to decomposing an orthogoual transformation into a shorter sequence of reflections. This paper proposes a simple algorithm of compressing versors of symbolic form in Clifford algebra. The algorithm is based on computing the intersections of lines with planes in the corresponding Grassmann-Cayley algebra, and is complete in the case of Euclidean or Minkowski inner-product space.

  18. Image compression for dermatology

    Science.gov (United States)

    Cookson, John P.; Sneiderman, Charles; Colaianni, Joseph; Hood, Antoinette F.

    1990-07-01

    Color 35mm photographic slides are commonly used in dermatology for education, and patient records. An electronic storage and retrieval system for digitized slide images may offer some advantages such as preservation and random access. We have integrated a system based on a personal computer (PC) for digital imaging of 35mm slides that depict dermatologic conditions. Such systems require significant resources to accommodate the large image files involved. Methods to reduce storage requirements and access time through image compression are therefore of interest. This paper contains an evaluation of one such compression method that uses the Hadamard transform implemented on a PC-resident graphics processor. Image quality is assessed by determining the effect of compression on the performance of an image feature recognition task.

  19. Compressing ultrafast electron pulse by radio frequency cavity

    Science.gov (United States)

    Pei, Min-Jie; Qi, Da-Long; Qi, Ying-Peng; Jia, Tian-Qing; Zhang, Shi-An; Sun, Zhen-Rong

    2017-04-01

    Not Available Project partially supported by the National Natural Science Foundation of China (Grant Nos. 51132004 and 11474096), the Fund from the Science and Technology Commission of Shanghai Municipality, China (Gant No. 14JC1401500), and the NYU-ECNU Institute of Physics at NYU Shanghai, China.

  20. Bi-alphabetic pulse compression radar signal design

    Indian Academy of Sciences (India)

    I A Pasha; P S Moharir; N Sudarshan Rao

    2000-10-01

    Ternary sequences have superior merit factors but they cannot be transmitted with existing technology. It is proposed that a ternary sequence be coded into a binary sequence for the purpose of transmission. On reception it can be processed as a binary sequence as received and also decoded into a ternary sequence. These two interpretations provide a coincidence detection scheme for efficient target detection provided that the corresponding signal design problem is solved. Such an algorithm is developed by taking the merit factor as desideratum and the Hamming scan as optimization technique. Merit factor values obtained in some cases are further improved by implementing a back-tracking algorithm for bi-alphabetic sequence.