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Sample records for based repetitive source

  1. A DSP-based repetition rate pulse source and its software reinforcement

    International Nuclear Information System (INIS)

    Against electromagnetic interference (EMI), a method based on DSP control, combining hardware protection with software reinforcement, is proposed in this paper. A repetition rate pulse source system is developed. A pulse source provides 5-way repetition rate pulses of 50 kV, with a minimum gap of 100 μs between two neighboring ways, and the pulses can be regulated continuously in 10-μs steps. A bounded-wave simulator system is used to prove feasibility of the method and the software reinforcement technology. The experimental results show that the DSP system using software reinforcement technology is well capable of reducing EMI. The system works properly in a simulated environment of repetition rate electromagnetic pulses. (authors)

  2. Steady State Microbunching for High Brilliance and High Repetition Rate Storage Ring-Based Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alex; Ratner, Daniel; /SLAC; Jiao, Yi; /Beijing, Inst. High Energy Phys.

    2012-09-06

    Electron-based light sources have proven to be effective sources of high brilliance, high frequency radiation. Such sources are typically either linac-Free Electron Laser (FEL) or storage ring types. The linac-FEL type has high brilliance (because the beam is microbunched) but low repetition rate. The storage ring type has high repetition rate (rapid beam circulation) but comparatively low brilliance or coherence. We propose to explore the feasibility of a microbunched beam in a storage ring that promises high repetition rate and high brilliance. The steady-state-micro-bunch (SSMB) beam in storage ring could provide CW sources for THz, EUV, or soft X-rays. Several SSMB mechanisms have been suggested recently, and in this report, we review a number of these SSMB concepts as promising directions for high brilliance, high repetition rate light sources of the future. The trick of SSMB lies in the RF system, together with the associated synchrotron beam dynamics, of the storage ring. Considering various different RF arrangements, there could be considered a number of scenarios of the SSMB. In this report, we arrange these scenarios more or less in order of the envisioned degree of technical challenge to the RF system, and not in the chronological order of their original references. Once the stored beam is steady-state microbunched in a storage ring, it passes through a radiator repeatedly every turn (or few turns). The radiator extracts a small fraction of the beam energy as coherent radiation with a wavelength corresponding to the microbunched period of the beam. In contrast to an FEL, this radiator is not needed to generate the microbunching (as required e.g. by SASE FELs or seeded FELs), so the radiator can be comparatively simple and short.

  3. Ultrafast, high repetition rate, ultraviolet, fiber based laser source: application towards Yb+ fast quantum-logic

    CERN Document Server

    Hussain, Mahmood Irtiza; Bentley, Christopher D B; Taylor, Richard L; Carvalho, Andre R R; Hope, Joseph J; Streed, Erik W; Lobino, Mirko; Kielpinski, David

    2016-01-01

    Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.5 ps ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with an average power of 190 mW. The laser wavelength is resonant with the strong transition in Ytterbium (Yb+) at 369.53 nm and its repetition rate can be scaled up using high harmonic mode locking. We show that our source can produce arbitrary pulse patterns using a programmable pulse pattern generator and fast modulating components. Finally, simulations demonstrate that our laser is capable of performing resonant, temperature-insensitive, two-qubit quantum logic gates on trapped Yb$^+$ ions faster than the trap period and with fidelity above 99%.

  4. A high repetition rate laser-heavy water based neutron source

    Science.gov (United States)

    Hah, Jungmoo; He, Zhaohan; Nees, John; Krushelnick, Karl; Thomas, Alexander; CenterUltrafast Optical Science Team

    2015-11-01

    Neutrons have numerous applications in diverse areas, such as medicine, security, and material science. For example, sources of MeV neutrons may be used for active interrogation for nuclear security applications. Recently, alternative ways to generate neutron flux have been studied. Among them, ultrashort laser pulse interactions with dense plasma have attracted significant attention as compact, pulse sources of neutrons. To generate neutrons using a laser through fusion reactions, thin solid density targets have been used in a pitcher-catcher arrangement, using deuterated plastic for example. However, the use of solid targets is limited for high-repetition rate operation due to the need to refresh the target for every laser shot. Here, we use a free flowing heavy water target with a high repetition rate (500 Hz) laser without a catcher. From the interaction between a 10 micron scale diameter heavy water stream with the Lambda-cubed laser system at the Univ. of Michigan (12mJ, 800nm, 35fs), deuterons collide with each other resulting in D-D fusion reactions generating 2.45 MeV neutrons. Under best conditions a time average of ~ 105 n/s of neutrons are generated.

  5. Repetitive sub-gigawatt rf source based on gyromagnetic nonlinear transmission line.

    Science.gov (United States)

    Romanchenko, Ilya V; Rostov, Vladislav V; Gubanov, Vladimir P; Stepchenko, Alexey S; Gunin, Alexander V; Kurkan, Ivan K

    2012-07-01

    We demonstrate a high power repetitive rf source using gyromagnetic nonlinear transmission line to produce rf oscillations. Saturated NiZn ferrites act as active nonlinear medium first sharpening the pumping high voltage nanosecond pulse and then radiating at central frequency of about 1 GHz: shock rise time excites gyromagnetic precession in ferrites forming damping rf oscillations. The optimal length of nonlinear transmission line was found to be of about 1 m. SINUS-200 high voltage driver with Tesla transformer incorporated into pulse forming line has been designed and fabricated to produce bursts of 1000 pulses with 200 Hz repetition rate. A band-pass filter and mode-converter have been designed to extract rf pulse from low-frequency component and to form TE(11) mode of circular waveguide with linear polarization. A wide-band horn antenna has been fabricated to form Gaussian distribution of radiation pattern. The peak value of electric field strength of a radiated pulse at the distance of 3.5 m away from antenna is measured to be 160 kV/m. The corresponding rf peak power of 260 MW was achieved. PMID:22852710

  6. Ultrafast, high repetition rate, ultraviolet, fiber-laser-based source: application towards Yb+ fast quantum-logic.

    Science.gov (United States)

    Hussain, Mahmood Irtiza; Petrasiunas, Matthew Joseph; Bentley, Christopher D B; Taylor, Richard L; Carvalho, André R R; Hope, Joseph J; Streed, Erik W; Lobino, Mirko; Kielpinski, David

    2016-07-25

    Trapped ions are one of the most promising approaches for the realization of a universal quantum computer. Faster quantum logic gates could dramatically improve the performance of trapped-ion quantum computers, and require the development of suitable high repetition rate pulsed lasers. Here we report on a robust frequency upconverted fiber laser based source, able to deliver 2.5 ps ultraviolet (UV) pulses at a stabilized repetition rate of 300.00000 MHz with an average power of 190 mW. The laser wavelength is resonant with the strong transition in Ytterbium (Yb+) at 369.53 nm and its repetition rate can be scaled up using high harmonic mode locking. We show that our source can produce arbitrary pulse patterns using a programmable pulse pattern generator and fast modulating components. Finally, simulations demonstrate that our laser is capable of performing resonant, temperature-insensitive, two-qubit quantum logic gates on trapped Yb+ ions faster than the trap period and with fidelity above 99%. PMID:27464118

  7. Repetitively pulsed UV radiation source based on a run-away electron preionised diffuse discharge in nitrogen

    Science.gov (United States)

    Baksht, E. Kh; Burachenko, A. G.; Lomaev, M. I.; Panchenko, A. N.; Tarasenko, V. F.

    2015-04-01

    An extended repetitively pulsed source of spontaneous UV radiation is fabricated, which may also be used for producing laser radiation. Voltage pulses with an incident wave amplitude of up to 30 kV, a half-amplitude duration of ~4 ns and a rise time of ~2.5 ns are applied to a gap with a nonuniform electric field. For an excitation region length of 35 cm and a nitrogen pressure of 30 - 760 Torr, a diffusive discharge up to a pulse repetition rate of 2 kHz is produced without using an additional system for gap preionisation. An investigation is made of the plasma of the run-away electron preionised diffuse discharge. Using a CCD camera it is found that the dense diffused plasma fills the gap in a time shorter than 1 ns. X-ray radiation is recorded from behind the foil anode throughout the pressure range under study; a supershort avalanche electron beam is recorded by the collector electrode at pressures below 100 Torr.

  8. A Z-source Inverter Based Flexible DG System with P+resonance and Repetitive Controllers for Power Quality Improvement of a Weak Grid

    DEFF Research Database (Denmark)

    Gajanayake, C.J.; Vilathgamuwa, D.M.; Loh, P.C.;

    2007-01-01

    , the utility has an obligation to deliver a quality supply to consumers. Interestingly, with the increase in energy demand and penetration of renewable sources, generation units popularly known as Distributed Generators (DGs) are increasingly connected at the distribution level. Most of these sources...... functions of the power distribution like harmonics and unbalance mitigation etc. Moreover, some of these DG sources have large operating ranges demanding special converters with wide operating range. Being a single stage buck-boost inverter, recently proposed Z-source inverter is a good candidate for future...... DG systems. Considering these factors, this paper presents the controller design for a Z-source inverter based DG system to improve the power quality of distribution systems. To improve the reference tracking and to eliminate harmonics, a p+resonance and repetitive controller designed using a simple...

  9. Bandwidth and repetition rate programmable Nyquist sinc-shaped pulse train source based on intensity modulators and four-wave mixing.

    Science.gov (United States)

    Cordette, S; Vedadi, A; Shoaie, M A; Brès, C-S

    2014-12-01

    We propose and experimentally demonstrate an all-optical Nyquist sinc-shaped pulse train source based on intensity modulation and four-wave mixing. The proposed scheme allows for the tunability of the bandwidth and the full flexibility of the repetition rate in the limit of the electronic bandwidth of the modulators used through the flexible synthesis of rectangular frequency combs. Bandwidth up to 360 GHz at 40 GHz rate and up to 45 frequency lines at 5 GHz rate are demonstrated with 40 GHz modulators.

  10. A smart repetitive-rate wideband high power microwave source

    International Nuclear Information System (INIS)

    A smart repetitive-rate wideband High Power Microwave (HPM) source based on the A6 Magnetron with Diffraction Output is described in this paper. The length of the HPM source is 30 cm and its weight is 35 kg. Computer simulations show that the source can produce microwave with central frequency of 1.91 GHz and bandwidth of about 11%. Experimental measurements show that the output microwave power from the source reaches in maximum 110 MW when the input electric power from the pulsed driver is ∼500 MW, which gives the power conversion efficiency 22%. Central frequency of the output HPM in the experiment is 1.94 GHz with the bandwidth ranging from 1.82 GHz to 2.02 GHz. The jitter of the output HPM power is lower than 3 dB when the source operates in the repetition mode with 50 Hz rate

  11. Simple filtered repetitively pulsed vacuum arc plasma source

    International Nuclear Information System (INIS)

    A very simple design of cathodic filtered vacuum arc plasma source is proposed. The source without filter has only four components and none of them require precise machining. The source operates in a repetitively pulsed regime, and for laboratory experiments it can be used without water cooling. Despite the simple construction, the source provides high ion current at the filter outlet reaching 2.5% of 400 A arc current, revealing stable operation in a wide pressure range from high vacuum to oxygen pressure up to more than 10-2 mbar. There is no need in complicated power supply system for this plasma source, only one power supply can be used to ignite the arc, to provide the current for the arc itself, to generate the magnetic field in the filter, and provide its positive electric biasing without any additional high power resistance.

  12. Injector Beam Dynamics for a High-Repetition Rate 4th-Generation Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulos, C. F.; Corlett, J.; Emma, P.; Filippetto, D.; Penn, G.; Qiang, J.; Reinsch, M.; Sannibale, F.; Steier, C.; Venturini, M.; Wells, R.

    2013-05-20

    We report on the beam dynamics studies and optimization methods for a high repetition rate (1 MHz) photoinjector based on a VHF normal conducting electron source. The simultaneous goals of beamcompression and reservation of 6-dimensional beam brightness have to be achieved in the injector, in order to accommodate a linac driven FEL light source. For this, a parallel, multiobjective optimization algorithm is used. We discuss the relative merits of different injector design points, as well as the constraints imposed on the beam dynamics by technical considerations such as the high repetition rate.

  13. Development of a picosecond CO2 laser system for a high-repetition γ-source

    Energy Technology Data Exchange (ETDEWEB)

    Polyanskiy, M.N.; Pogorelsky, I.V.; Yakimenko, V.E.; Platonenko, V.T.

    2009-04-17

    The concept of a high-repetition-rate, high-average power {gamma}-source is based on Compton backscattering from the relativistic electron beam inside a picosecond CO{sub 2} laser cavity. Proof-of-principle experiments combined with computer simulations allow evaluating the promise of this approach for novel applications in science and technology.

  14. A high repetition rate XUV seeding source for FLASH2

    Energy Technology Data Exchange (ETDEWEB)

    Willner, Arik

    2012-05-15

    Improved performance of free-electron laser (FEL) light sources in terms of timing stability, pulse shape and spectral properties of the amplified FEL pulses is of interest in material science, the fields of ultrafast dynamics, biology, chemistry and even special branches in industry. A promising scheme for such an improvement is direct seeding with high harmonic generation (HHG) in a noble gas target. A free-electron laser seeded by an external extreme ultraviolet (XUV) source is planned for FLASH2 at DESY in Hamburg. The requirements for the XUV/soft X-ray source can be summarized as follows: A repetition rate of at least 100 kHz in a 10 Hz burst is needed at variable wavelengths from 10 to 40 nm and pulse energies of several nJ within a single laser harmonic. This application requires a laser amplifier system with exceptional parameters, mJ-level pulse energy, 10-15 fs pulse duration at 100 kHz (1 MHz) burst repetition rate. A new optical parametric chirped-pulse amplification (OPCPA) system is under development in order to meet these requirements, and very promising results have been achieved in the last three years. In parallel to this development, a new HHG concept is necessary to sustain high average power of the driving laser system and to generate harmonics with high conversion efficiencies. Currently, the highest conversion efficiency with HHG has been demonstrated using gas-filled capillary targets. For our application, only a free-jet target can be used for HHG, in order to overcome damage threshold limitations of HHG target optics at a high repetition rate. A novel dual-gas multijet gas target has been developed and first experiments show remarkable control of the degree of phase matching forming the basis for improved control of the harmonic photon flux and the XUV pulse characteristics. The basic idea behind the dual-gas concept is the insertion of matching zones in between multiple HHG sources. These matching sections are filled with hydrogen which

  15. A high repetition rate XUV seeding source for FLASH2

    International Nuclear Information System (INIS)

    Improved performance of free-electron laser (FEL) light sources in terms of timing stability, pulse shape and spectral properties of the amplified FEL pulses is of interest in material science, the fields of ultrafast dynamics, biology, chemistry and even special branches in industry. A promising scheme for such an improvement is direct seeding with high harmonic generation (HHG) in a noble gas target. A free-electron laser seeded by an external extreme ultraviolet (XUV) source is planned for FLASH2 at DESY in Hamburg. The requirements for the XUV/soft X-ray source can be summarized as follows: A repetition rate of at least 100 kHz in a 10 Hz burst is needed at variable wavelengths from 10 to 40 nm and pulse energies of several nJ within a single laser harmonic. This application requires a laser amplifier system with exceptional parameters, mJ-level pulse energy, 10-15 fs pulse duration at 100 kHz (1 MHz) burst repetition rate. A new optical parametric chirped-pulse amplification (OPCPA) system is under development in order to meet these requirements, and very promising results have been achieved in the last three years. In parallel to this development, a new HHG concept is necessary to sustain high average power of the driving laser system and to generate harmonics with high conversion efficiencies. Currently, the highest conversion efficiency with HHG has been demonstrated using gas-filled capillary targets. For our application, only a free-jet target can be used for HHG, in order to overcome damage threshold limitations of HHG target optics at a high repetition rate. A novel dual-gas multijet gas target has been developed and first experiments show remarkable control of the degree of phase matching forming the basis for improved control of the harmonic photon flux and the XUV pulse characteristics. The basic idea behind the dual-gas concept is the insertion of matching zones in between multiple HHG sources. These matching sections are filled with hydrogen which

  16. Final Report, Photocathodes for High Repetition Rate Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, Ilan [Stony Brook University

    2014-04-20

    This proposal brought together teams at Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL) and Stony Brook University (SBU) to study photocathodes for high repetition rate light sources such as Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). The work done under this grant comprises a comprehensive program on critical aspects of the production of the electron beams needed for future user facilities. Our program pioneered in situ and in operando diagnostics for alkali antimonide growth. The focus is on development of photocathodes for high repetition rate Free Electron Lasers (FELs) and Energy Recovery Linacs (ERLs), including testing SRF photoguns, both normal-conducting and superconducting. Teams from BNL, LBNL and Stony Brook University (SBU) led this research, and coordinated their work over a range of topics. The work leveraged a robust infrastructure of existing facilities and the support was used for carrying out the research at these facilities. The program concentrated in three areas: a) Physics and chemistry of alkali-antimonide cathodes b) Development and testing of a diamond amplifier for photocathodes c) Tests of both cathodes in superconducting RF photoguns and copper RF photoguns

  17. Repetitive electron beam source for high power microwave experiments

    International Nuclear Information System (INIS)

    A compact pulse transformer has been developed to operate at ∼1 Hz, producing a 100 kV, 250 ns pulse. The output pulse has a ±1% flat top for 120 ns. This pulse is coupled to an electron beam diode which uses a ferroelectric ceramic disk as the source of a high current density electron beam. A portion of the pulse (∼ 2 kV) is applied across the ferroelectric causing a rapid change in the polarization state. This change results in the emission of a high density electron cloud into an accelerating diode gap. The accelerating pulse is applied across the diode gap and the electron beam is extracted into a cylindrical drift tube. A magnetic guide field is supplied by a 5 cm diameter pulsed coil system. They have reported results from the ferroelectric ceramic as an electron source. The diode gap is adjusted between 110 mm and the anode potential is varied from 0--500 V. The emitted current is measured as a function these parameters. Current densities of 70 A/cm2 have, been measured. The Child-Langmuir current density, for 500 V applied across a 4 mm gap, is 0.2 A/cm2. These results will be summarized and compared to predictions from an analytical model that has been developed. They are planning to increase the repetition rate pulser output to 500 kV, 800 A in the near future. In addition they are attempting to modulate the emitted electron cloud by applying an RF voltage at 2.45 GHz to the diode gap. Initial results from this experiment will also be presented

  18. Repetition-based Interactive Facade Modeling

    KAUST Repository

    AlHalawani, Sawsan

    2012-07-01

    Modeling and reconstruction of urban environments has gained researchers attention throughout the past few years. It spreads in a variety of directions across multiple disciplines such as image processing, computer graphics and computer vision as well as in architecture, geoscience and remote sensing. Having a virtual world of our real cities is very attractive in various directions such as entertainment, engineering, governments among many others. In this thesis, we address the problem of processing a single fa cade image to acquire useful information that can be utilized to manipulate the fa cade and generate variations of fa cade images which can be later used for buildings\\' texturing. Typical fa cade structures exhibit a rectilinear distribution where in windows and other elements are organized in a grid of horizontal and vertical repetitions of similar patterns. In the firt part of this thesis, we propose an efficient algorithm that exploits information obtained from a single image to identify the distribution grid of the dominant elements i.e. windows. This detection method is initially assisted with the user marking the dominant window followed by an automatic process for identifying its repeated instances which are used to define the structure grid. Given the distribution grid, we allow the user to interactively manipulate the fa cade by adding, deleting, resizing or repositioning the windows in order to generate new fa cade structures. Having the utility for the interactive fa cade is very valuable to create fa cade variations and generate new textures for building models. Ultimately, there is a wide range of interesting possibilities of interactions to be explored.

  19. A Repetitive Nanosecond Pulse Source for Generation of Large Volume Streamer Discharge

    Institute of Scientific and Technical Information of China (English)

    TAO Fengbo; ZHANG Qiaogen; GAO Bo; WANG Hu; LI Zhou

    2008-01-01

    Using a unipolar pulse with the rise time and the pulse duration in the order of microsecond as the primary pulse,a nanosecond pulse with the repetitive frequency of several kilohertz is generated by a spark gap switch.By varying both the inter-pulse duration and the pulse frequency,the voltage recovery rate of the spark gap switch is investigated at different working conditions such as the gas pressure,the gas composition as well as the bias voltage.The results reveal that either increase in gas pressure or addition of SF6 to the air can increase the voltage recovery rate.The effect of gas composition on the voltage recovery rate is discussed based on the transferring and distribution of the residual space charges.The repetitive nanosecond pulse source is also applied to the generation of large volume,and the discharge currents are measured to investigate the effect of pulse repetition rate on the large volume streamer discharge.

  20. A New Revised DNA Cramp Tool Based Approach of Chopping DNA Repetitive and Non-Repetitive Genome Sequences

    Directory of Open Access Journals (Sweden)

    V.Hari Prasad

    2012-11-01

    Full Text Available In vogue tremendous amount of data generated day by day by the living organism of genetic sequences and its accumulation in database, their size is growing in an exponential manner. Due to excessive storage of DNA sequences in public databases like NCBI, EMBL and DDBJ archival maintenance is tedious task. Transmission of information from one place to another place in network management systems is also a critical task. So To improve the efficiency and to reduce the overhead of the database need of compression arises in database optimization. In this connection different techniques were bloomed, but achieved results are not bountiful. Many classical algorithms are fails to compress genetic sequences due to the specificity of text encoded in dna and few of the existing techniques achieved positive results. DNA is repetitive and non repetitive in nature. Our proposed technique DNACRAMP is applicable on repetitive and non repetitive sequences of dna and it yields better compression ratio in terms of bits per bases. This is compared with existing techniques and observed that our one is the optimum technique and compression results are on par with existing techniques.

  1. Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

    Energy Technology Data Exchange (ETDEWEB)

    Wang, He [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Xu, Yiming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ulonska, Stefan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Robinson, Joseph S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ranitovic, Predrag [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Kaindl, Robert A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

    2015-06-11

    Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. In this article, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 1013 s-1 is generated at 22.3 eV, with 5 × 10-5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Finally, spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications.

  2. The discovery of rapidly repetitive X-ray bursts from a new source in Scorpius

    Science.gov (United States)

    Lewin, W. H. G.; Doty, J.; Clark, G. W.; Bradt, H. V. D.; Doxsey, R.; Hearn, D. R.; Hoffman, J. A.; Jernigan, J. G.; Li, F. K.; Rappaport, S. A.

    1976-01-01

    Rapidly repetitive X-ray bursts have been observed from a new X-ray source in Scorpius. More than 2000 bursts were observed during the 4-day continual SAS-3 observations of this source designated MXB 1730-335. The time interval between bursts varied from a minimum of about 6 s to a maximum of about 5 minutes. The energy in a given burst is approximately linearly proportional to the time interval to the next burst. The largest bursts observed last for about 60 s and represent an energy release of approximately 10 to the 40th ergs for an assumed distance to the source of 10 kpc. The smallest bursts observed last only for a few seconds. We suggest that the bursts are caused by sporadic precipitations of plasma from a reservoir in the magnetosphere of a neutron star. The reservoir is replenished at a nearly constant rate by mass transferred from a binary companion.

  3. Repetition-based credibility enhancement of unfamiliar faces.

    Science.gov (United States)

    Brown, Alan S; Brown, Lori A; Zoccoli, Sandy L

    2002-01-01

    This experiment demonstrated that rating the credibility of nonfamous faces results in a significant increase in rated credibility on a subsequent encounter relative to new nonfamous faces. The degree of credibility enhancement is comparable for both honesty and sincerity ratings and at both short (2-day) and long (14-day) interrating intervals. Furthermore, credibility enhancement was independent of recognition; ratings were significantly higher for repeated faces, regardless of whether they were remembered. Although female faces were rated more credible than male faces, there was no gender difference in the degree of credibility enhancement with repetition. Conditional analyses revealed that actual, rather than perceived, repetition formed the basis of credibility enhancement. Future research should compare repetition effects on both credibility and affect as well as the durability of such effects over time. PMID:12041008

  4. Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

    CERN Document Server

    Wang, He; Ulonska, Stefan; Ranitovic, Predrag; Robinson, Joseph S; Kaindl, Robert A

    2014-01-01

    Novel table-top sources of extreme ultraviolet (XUV) light based on high-harmonic generation (HHG) yield unique insight into the fundamental properties of molecules, nanomaterials, or correlated solids, and enable advanced applications in imaging or metrology. Extending HHG to high repetition rates portends great experimental benefits, yet efficient XUV conversion of correspondingly weak driving pulses is challenging. Here, we demonstrate a highly-efficient source of femtosecond XUV pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ~3e13 per second is generated at 22.3 eV, with 5e-5 conversion efficiency that surpasses similar directly-driven harmonics by two orders-of-magnitude. This enhancement exceeds the predicted dipole wavelength scaling, evidencing improved phase-matching for ultraviolet-driven HHG under tight focusing as corroborated by simulations. Spectral isolation of a single sub-80 meV harmonic re...

  5. Repetitive Operation of A Dense Plasma Soft X-ray Source for Micromachining

    Science.gov (United States)

    Wong, D.; Tan, T. L.; Patran, A.; Hassan, S. M.; Zhang, T.; Springham, S. V.; Lee, S.; Rawat, R. S.; Lee, P.

    2006-01-01

    The NX2 device, a low energy plasma focus, at the Nanyang Technological University in Singapore, was used as a soft X-ray (SXR) source for micromachining. The gas used was neon which produced SXRs in a narrow spectral range of 0.9 - 1.6 keV. The SXR yield from repetitive operation of the NX2 device was monitored and measured using a cost effective multi-channel SXR spectrometric system. The system consists of filtered BPX65 PIN diodes, with the associated electronics — an integrator, sample and peak holder, analogue switch, an A/D converter and a microcontroller. The system enables easy shot-to-shot statistical analysis under repetitive operation at adjustable preset trigger frequencies. A total of 4000 shots were fired at 0.5 Hz, using the same gas filling. The SXR production was at an average yield of 60 J/shot and a maximum single-shot yield of more than 100 J. The SXRs emitted by the NX2 device was used for contact micromachining, producing structures with an excellent aspect ratio of up to 20:1 on 25 μm SU-8 resist.

  6. Microchannel plate (MCP) focusing optics for a repetitive laser-plasma source

    International Nuclear Information System (INIS)

    The authors describe the use of microchannel plate (MCP) optics to focus soft X-rays produced by the Rutherford Appleton Laboratory (RAL) high brightness plasma source. In this source the X-ray emitting plasma is generated by a high repetition rate, picosecond pulsed excimer laser system. A low cost, low debris, high intensity soft X-ray beamline results from the combination of this bright, point-like, plasma source with a planar square-pore MCP optic. Fluxes of 9 x 109 photon/mm2/s at 33.7 angstrom wavelength and 4 x 107 photon/mm2/s at 7.8 angstrom wavelength have been recorded at the MCP focus. This paper also describes the exploitation of the RAL source for the characterization of prototype MCP optics. Investigations into both planar MCPs with square pores and spherically slumped MCPs with circular pores are reported. The small (10microm diameter) size of the plasma source coupled with an ability to make absolute flux measurements greatly facilitates the calibration process

  7. A repetitive sequence assembler based on next-generation sequencing.

    Science.gov (United States)

    Lian, S; Tu, Y; Wang, Y; Chen, X; Wang, L

    2016-01-01

    Repetitive sequences of variable length are common in almost all eukaryotic genomes, and most of them are presumed to have important biomedical functions and can cause genomic instability. Next-generation sequencing (NGS) technologies provide the possibility of identifying capturing these repetitive sequences directly from the NGS data. In this study, we assessed the performances in identifying capturing repeats of leading assemblers, such as Velvet, SOAPdenovo, SGA, MSR-CA, Bambus2, ALLPATHS-LG, and AByss using three real NGS datasets. Our results indicated that most of them performed poorly in capturing the repeats. Consequently, we proposed a repetitive sequence assembler, named NGSReper, for capturing repeats from NGS data. Simulated datasets were used to validate the feasibility of NGSReper. The results indicate that the completeness of capturing repeat is up to 99%. Cross validation was performed in three real NGS datasets, and extensive comparisons indicate that NGSReper performed best in terms of completeness and accuracy in capturing repeats. In conclusion, NGSReper is an appropriate and suitable tool for capturing repeats directly from NGS data. PMID:27525861

  8. ERIC-PCR技术对单增李斯特菌的溯源分析%Biotracing the source of Listeria monocytogenes strains by enterobacterial repetitive intergenic consensus sequence-based PCR

    Institute of Scientific and Technical Information of China (English)

    刘海泉; 朱颖; 姜文洁; 孙晓红; 吴启华; 潘迎捷; 赵勇

    2013-01-01

    Enterobacterial repetitive intergenic consensus sequence (ERIC )-PCR was used to genotype 17 strains of Listeria monocytogenes,which were isolated from pork samples of the three market,and we investigated the correlation between the genotype,regional distribution and prevalence among L monocytogenes strains. L monocytogenes ATCC 19115 was used as positive control. The result showed that 17 isolates were identified as six special genotypes,and genotype IV was the dominant one as the main pollution group,which were isolated from the third market. The strains isolated from the first and second market were genotype I and genotype IV .respcetively. The result suggested that ERIC-PCR was suitable to investigate the biotracing of L. monocytogenes and it was a more rapid,efficient,and accurate molecular typing method than traditional serotyping methods.%以质控菌株ATCC 19115为对照,采用ERIC-PCR方法对从三个市场猪肉样品分离到的17株单增李斯特菌(Listeria monocytogenes)进行了基因分型,探讨了单增李斯特菌基因型与区域分布及流行性的关联性.结果表明,17株单增李斯特菌菌株可分为六个主要基因类群,其中Ⅳ型菌株最多,为主要污染类群,而这些菌株来自于市场三;市场一和市场二分离到的菌株主要分别为Ⅰ型和Ⅳ型.因此,ERIC-PCR方法适用于对单增李斯特菌的溯源分析和流行病学调查,具有简单、方便、快捷、准确的特点.

  9. Counter-facing plasma focus system as a repetitive and/or long-pulse high energy density plasma source

    Science.gov (United States)

    Aoyama, Yutaka; Nakajima, Mitsuo; Horioka, Kazuhiko

    2009-11-01

    A plasma focus system composed of a pair of counter-facing coaxial plasma guns is proposed as a long-pulse and/or repetitive high energy density plasma source. A proof-of-concept experiment demonstrated that with an assist of breakdown and outer electrode connections, current sheets evolved into a configuration for stable plasma confinement at the center of the electrodes. The current sheets could successively compress and confine the high energy density plasma every half period of the discharge current, enabling highly repetitive light emissions in extreme ultraviolet region with time durations in at least ten microseconds.

  10. Repetition rate tunable ultra-short optical pulse generation based on electrical pattern generator

    Institute of Scientific and Technical Information of China (English)

    Xin Fu; Hongming Zhang; Meng Yan; Minyu Yao

    2009-01-01

    @@ An actively mode-locked laser with tunable repetition rate is proposed and experimentally demonstrated based on a programmable electrical pattern generator.By changing the repetition rate of the electrical patterns applied on the in-cavity modulator, the repetition rate of the output optical pulse sequences changes accordingly while the pulse width of the optical pulse train remains almost constant.In other words, the output ultra-short pulse train has a tunable duty cycle.In a proof-of-principle experiment, optical pulses with repetition rates of 10, 5, 2.5 and 1.25 GHz are obtained by adjusting the electrical pattern applied on the in-cavity modulator while their pulse widths remain almost unchanged.

  11. Use of Repetitive DNA Sequences and the PCR To Differentiate Escherichia coli Isolates from Human and Animal Sources

    OpenAIRE

    Dombek, Priscilla E.; Johnson, LeeAnn K.; Zimmerley, Sara T.; Michael J Sadowsky

    2000-01-01

    The rep-PCR DNA fingerprint technique, which uses repetitive intergenic DNA sequences, was investigated as a way to differentiate between human and animal sources of fecal pollution. BOX and REP primers were used to generate DNA fingerprints from Escherichia coli strains isolated from human and animal sources (geese, ducks, cows, pigs, chickens, and sheep). Our initial studies revealed that the DNA fingerprints obtained with the BOX primer were more effective for grouping E. coli strains than...

  12. Performance of a high repetition pulse rate laser system for in-gas-jet laser ionization studies with the Leuven laser ion source LISOL

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, R., E-mail: Rafael.Ferrer@fys.kuleuven.be [Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Sonnenschein, V.T. [Department of Physics, University of Jyvaeskylae, P.O. Box 35 (YFL), FI-40014 Jyvaeskylae (Finland); Bastin, B. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Franchoo, S. [Institut de Physique Nucleaire (IPN) d' Orsay, 91406 Orsay, Cedex (France); Huyse, M.; Kudryavtsev, Yu. [Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Kron, T. [Institut fuer Physik, Universitaet Mainz, D-55128 Mainz (Germany); Lecesne, N. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Moore, I.D. [Department of Physics, University of Jyvaeskylae, P.O. Box 35 (YFL), FI-40014 Jyvaeskylae (Finland); Osmond, B. [GANIL, CEA/DSM-CNRS/IN2P3, B.P. 55027, 14076 Caen (France); Pauwels, D. [SCK-CEN, Belgian Nuclear Research Center, Boeretang 200, 2400 Mol (Belgium); Radulov, D. [Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Raeder, S. [Institut fuer Physik, Universitaet Mainz, D-55128 Mainz (Germany); Rens, L. [Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); and others

    2012-11-15

    The laser ionization efficiency of the Leuven gas cell-based laser ion source was investigated under on- and off-line conditions using two distinctly different laser setups: a low-repetition rate dye laser system and a high-repetition rate Ti:sapphire laser system. A systematic study of the ion signal dependence on repetition rate and laser pulse energy was performed in off-line tests using stable cobalt and copper isotopes. These studies also included in-gas-jet laser spectroscopy measurements on the hyperfine structure of {sup 63}Cu. A final run under on-line conditions in which the radioactive isotope {sup 59}Cu (T{sub 1/2} = 81.5 s) was produced, showed a comparable yield of the two laser systems for in-gas-cell ionization. However, a significantly improved time overlap by using the high-repetition rate laser system for in-gas-jet ionization was demonstrated by an increase of the overall duty cycle, and at the same time, pointed to the need for a better shaped atomic jet to reach higher ionization efficiencies.

  13. Dual-frequency comb generation with differing GHz repetition rates by parallel Fabry-Perot cavity filtering of a single broadband frequency comb source

    Science.gov (United States)

    Mildner, Jutta; Meiners-Hagen, Karl; Pollinger, Florian

    2016-07-01

    We present a dual-comb-generator based on a coupled Fabry-Perot filtering cavity doublet and a single seed laser source. By filtering a commercial erbium-doped fiber-based optical frequency comb with CEO-stabilisation and 250 MHz repetition rate, two broadband coherent combs of different repetition rates in the GHz range are generated. The filtering doublet consists of two Fabry-Perot cavities with a tunable spacing and Pound-Drever-Hall stabilisation scheme. As a prerequisite for the development of such a filtering unit, we present a method to determine the actual free spectral range and transmission bandwidth of a Fabry-Perot cavity in situ. The transmitted beat signal of two diode lasers is measured as a function of their tunable frequency difference. Finally, the filtering performance and resulting beat signals of the heterodyned combs are discussed as well as the optimisation measures of the whole system.

  14. Articulation-based sound perception in verbal repetition: A functional NIRS study

    Directory of Open Access Journals (Sweden)

    Sejin eYoo

    2013-09-01

    Full Text Available Verbal repetition is a fundamental language capacity where listening and speaking are inextricably coupled with each other. We have recently reported that the left inferior frontal gyrus (IFG harbors articulation-based codes, as evidenced by activation during repetition of meaningless speech sounds, i.e., pseudowords. In this study, we aimed at confirming this finding and further investigating the possibility that sound perception as well as articulation is subserved by neural circuits in this region. Using functional near-infrared spectroscopy (fNIRS, we monitored changes of hemoglobin (Hb concentration at IFG bilaterally, while subjects verbally repeated pseudowords and words. The results revealed that the proportion of oxygenated hemoglobin (O2Hb over total Hb was significantly higher at the left IFG during repetition of pseudowords than that of words, replicating the observation by functional MRI and indicating that the region processes articulatory codes for verbal repetition. More importantly for this study, hemodynamic modulations were observed at both IFG during passive listening without repetition to various sounds, including natural environmental sounds, animal vocalizations, and human nonspeech sounds. Furthermore, the O2Hb concentration increased at the left IFG but decreased at the right IFG for both speech and non-speech sounds. These findings suggest that both speech and non-speech sounds may be processed and maintained by a neural mechanism for sensorimotor integration using articulatory codes at the left IFG.

  15. High-repetition rate, picosecond-pulse, tunable, mid-IR PPLN OPG source

    Science.gov (United States)

    Isyanova, Yelena; Tian, Wenyan; Moulton, Peter F.

    2016-03-01

    We report here on the performance of a narrow-line, mid-IR source based on a PPLN-crystal optical parametric generator (OPG). The crystal was pumped by a pulsed, 20-MHz-rate, 1064-nm Yb:fiber-based source operating with 20- psec pulses. The OPG produced a broad spectrum between 2027 nm and 2239 nm. By placing a band-pass filter after the OPG we were able to select a 30-nm bandwidth output, and we achieved further line reduction (0.7 nm) and 4.5 mW of average power at 2039 nm, using a reflective Volume Bragg Grating (VBG). Devices such as piezo-controlled etalons can provide rapidly tunable, narrow-linewidth power from this system.

  16. Plasmon-enhanced photocathode for high brightness and high repetition rate x-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Polyakov, Aleksandr; Senft, Christoph; Thompson, K. F.; Feng, J.; Cabrini, S.; Schuck, P. J.; Padmore, Howard; Peppernick, Samuel J.; Hess, Wayne P.

    2013-02-11

    High brightness electron sources are at the heart of anew generation of x-ray sources based on the Free ElectronLaser (FEL) as well as in Energy Recovery Linac (ERL) and Inverse Compton Scattering (ICS) sources.The source of electrons consists of a photoinjector, comprised of a laser-driven photocathode in a high gradient electric field produced by an rf cavity. The function of the rf cavity is to provide a field sufficient for acceleration of electrons to relativistic velocity over a small distance, thus minimizing effects of the space-charge. Even so, the dense electron beam required for high brightness suffers from a space charge field that chirps and reshapes the electron pulse increasing beam emittance and thus reducing the overall brightness. This emittance growth can be avoided if the initial distribution of electrons is pancake shaped, with a semicircular transverse intensity profile. In this case, the electron distribution develops under its space charge field from a pancake into a uniformly filled ellipsoidal beam. This condition, referred to as the blowout regime, requires ultrashort pulses less than 100 fs long and has been successfully demonstrated recently in a high gradient photoinjector.

  17. Evaluation of Repetitive Element Sequence-Based PCR as a Molecular Typing Method for Clostridium difficile

    OpenAIRE

    Spigaglia, Patrizia; Mastrantonio, Paola

    2003-01-01

    Repetitive element sequence-based PCR (rep-PCR) is a typing method that enables the generation of DNA fingerprinting that discriminates bacterial strains. In this study, we evaluated the applicability of rep-PCR in typing Clostridium difficile clinical isolates. The results obtained by rep-PCR were compared with those obtained by pulsed-field gel electrophoresis (PFGE) and PCR ribotyping. A high correspondence between pattern differentiations produced by rep-PCR and PFGE was observed, whereas...

  18. Risk factors for repetition of self-harm: a systematic review of prospective hospital-based studies.

    Directory of Open Access Journals (Sweden)

    Celine Larkin

    Full Text Available BACKGROUND: Self-harm entails high costs to individuals and society in terms of suicide risk, morbidity and healthcare expenditure. Repetition of self-harm confers yet higher risk of suicide and risk assessment of self-harm patients forms a key component of the health care management of self-harm patients. To date, there has been no systematic review published which synthesises the extensive evidence on risk factors for repetition. OBJECTIVE: This review is intended to identify risk factors for prospective repetition of self-harm after an index self-harm presentation, irrespective of suicidal intent. DATA SOURCES: PubMed, PsychInfo and Scirus were used to search for relevant publications. We included cohort studies which examining factors associated with prospective repetition among those presenting with self-harm to emergency departments. Journal articles, abstracts, letters and theses in any language published up to June 2012 were considered. Studies were quality-assessed and synthesised in narrative form. RESULTS: A total of 129 studies, including 329,001 participants, met our inclusion criteria. Some factors were studied extensively and were found to have a consistent association with repetition. These included previous self-harm, personality disorder, hopelessness, history of psychiatric treatment, schizophrenia, alcohol abuse/dependence, drug abuse/dependence, and living alone. However, the sensitivity values of these measures varied greatly across studies. Psychological risk factors and protective factors have been relatively under-researched but show emerging associations with repetition. Composite risk scales tended to have high sensitivity but poor specificity. CONCLUSIONS: Many risk factors for repetition of self-harm match risk factors for initiation of self-harm, but the most consistent evidence for increased risk of repetition comes from long-standing psychosocial vulnerabilities, rather than characteristics of an index episode

  19. A repetitive long-pulse power generator based on pulse forming network and linear transformer driver.

    Science.gov (United States)

    Li, Mingjia; Kang, Qiang; Tan, Jie; Zhang, Faqiang; Luo, Min; Xiang, Fei

    2016-06-01

    A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ∼50 ns and a flat top of ∼100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ∼560 kV, output current amplitude of ∼10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 10(4) pulses. Meanwhile, the continuous operating time of the generator is up to 60 s. PMID:27370479

  20. A repetitive long-pulse power generator based on pulse forming network and linear transformer driver

    Science.gov (United States)

    Li, Mingjia; Kang, Qiang; Tan, Jie; Zhang, Faqiang; Luo, Min; Xiang, Fei

    2016-06-01

    A compact module for long-pulse power generator, based on Blumlein pulse forming network (PFN), was designed. Two Blumlein PFNs with L-type configuration and 20 Ω characteristic impedance were connected symmetrically to the primary coil of the linear transformer driver (LTD) and driven by an identical high voltage spark switch to ensure two Blumlein PFNs synchronizing operation. The output pulse of the module connected with 10 Ω water load is about 135 kV in amplitude and 200 ns in duration with a rise time of ˜50 ns and a flat top of ˜100 ns. On this basis, a repetitive long-pulse power generator based on PFN-LTD has been developed, which was composed of four modules. The following technical parameters of the generator were achieved on planar diode: output voltage amplitude of ˜560 kV, output current amplitude of ˜10 kA at a repetition rate of 25 Hz. The generator operates stable and outputs more than 104 pulses. Meanwhile, the continuous operating time of the generator is up to 60 s.

  1. Investigation of bunch repetition rate deviations in FIR FEL driven by a magnetron-based microtron

    CERN Document Server

    Kazakevitch, Grigori M; Lee Byung Cheol; Lee, J

    2002-01-01

    The stability of the bunch repetition rate in a FIR FEL driven by a 2.8 GHz magnetron-based microtron was investigated using a heterodyne method with a low Q-factor straight-flight measuring cavity. The measuring cavity is located in the straight section of the FIR FEL injection beam line and is excited by the passage of electron bunches. The RF signal from the measuring cavity coupling loop was mixed with a precise heterodyne signal with a frequency difference of several MHz. The beat frequency was analyzed to obtain the temporal distribution of the bunch repetition rate deviation during the macro pulse of the electron beam. The time resolution and the accuracy of measurements are approximately 100 ns and a few kHz, respectively. Based on this data, we could determine the level and shape of the magnetron current and the initial frequency shift between magnetron and accelerating cavity for the FEL operation in the wavelength range 100-300 microns.

  2. Internal-Model-Principle-Based Specific Harmonics Repetitive Controller for Grid-Connected PWM Inverters

    Directory of Open Access Journals (Sweden)

    Wenzhou Lu

    2016-01-01

    Full Text Available This paper analyzes the general properties of IMP-based controller and presents an internal-model-principle-based (IMP-based specific harmonics repetitive control (SHRC scheme. The proposed SHRC is effective for specific nk±m order harmonics, with n>m≥0 and k=0,1,2,…. Using the properties of exponential function, SHRC can also be rewritten into the format of multiple resonant controllers in parallel, where the control gain of SHRC is n/2 multiple of that of conventional RC (CRC. Therefore, including SHRC in a stable closed-loop feedback control system, asymptotic disturbance eliminating, or reference tracking for any periodic signal only including these specific harmonic components at n/2 times faster error convergence rate compared with CRC can be achieved. Application examples of SHRC controlled three-phase/single-phase grid-connected PWM inverters demonstrate the effectiveness and advantages of the proposed SHRC scheme.

  3. Repetitive sequence based polymerase chain reaction to differentiate close bacteria strains in acidic sites

    Institute of Scientific and Technical Information of China (English)

    XIE Ming; YIN Hua-qun; LIU Yi; LIU Jie; LIU Xue-duan

    2008-01-01

    To study the diversity of bacteria strains newly isolated from several acid mine drainage(AMD) sites in China,repetitive sequence based polymerase chain reaction (rep-PCR),a well established technology for diversity analysis of closely related bacteria strains,was conducted on 30 strains of bacteria Leptospirillum ferriphilium,8 strains of bacteria Acidithiobacillus ferrooxidans,as well as the Acidithiobacillus ferrooxidans type strain ATCC (American Type Culture Collection) 23270.The results showed that,using ERIC and BOX primer sets,rep-PCR produced highly discriminatory banding patterns.Phylogenetic analysis based on ERIC-PCR banding types was made and the results indicated that rep-PCR could be used as a rapid and highly discriminatory screening technique in studying bacterial diversity,especially in differentiating bacteria within one species in AMD.

  4. Grammatical Change through Repetition.

    Science.gov (United States)

    Arevart, Supot

    1989-01-01

    The effect of repetition on grammatical change in an unrehearsed talk is examined based on a case study of a single learner. It was found that repetition allows for accuracy monitoring in that errors committed in repeated contexts undergo correction. Implications for teaching are discussed. (23 references) (LB)

  5. Use of 16S-23S rRNA Intergenic Spacer Region PCR and Repetitive Extragenic Palindromic PCR Analyses of Escherichia coli Isolates To Identify Nonpoint Fecal Sources

    OpenAIRE

    Seurinck, Sylvie; Verstraete, Willy; Siciliano, Steven D.

    2003-01-01

    Despite efforts to minimize fecal input into waterways, this kind of pollution continues to be a problem due to an inability to reliably identify nonpoint sources. Our objective was to find candidate source-specific Escherichia coli fingerprints as potential genotypic markers for raw sewage, horses, dogs, gulls, and cows. We evaluated 16S-23S rRNA intergenic spacer region (ISR)-PCR and repetitive extragenic palindromic (rep)-PCR analyses of E. coli isolates as tools to identify nonpoint fecal...

  6. Automatic Generation of Deep Web Wrappers based on Discovery of Repetition

    OpenAIRE

    Nakatoh, Tetsuya; Yamada, Yasuhiro; Hirokawa, Sachio

    2004-01-01

    A Deep Web wrapper is a program that extracts contents from search results. We propose a new automatic wrapper generation algorithm which discovers a repetitive pattern from search results. The repetitive pattern is expressed by token sequences which consist of HTML tags, plain texts and wild-cards. The algorithm applies a string matching with mismatches to unify the variation from the template and uses FFT(fast Fourier transformation) to attain efficiency. We show an empirical evaluation of ...

  7. Parallel Repetition From Fortification

    OpenAIRE

    Moshkovitz Aaronson, Dana Hadar

    2014-01-01

    The Parallel Repetition Theorem upper-bounds the value of a repeated (tensored) two prover game in terms of the value of the base game and the number of repetitions. In this work we give a simple transformation on games – “fortification” – and show that for fortified games, the value of the repeated game decreases perfectly exponentially with the number of repetitions, up to an arbitrarily small additive error. Our proof is combinatorial and short. As corollaries, we obtain: (1) Starting from...

  8. A contactless microwave-based diagnostic tool for high repetition rate laser systems

    CERN Document Server

    Braggio, C

    2014-01-01

    We report on a novel electro-optic device for the diagnostics of high repetition rate laser systems. It is composed of a microwave receiver and of a second order nonlinear crystal, whose irradiation with a train of short laser pulses produces a time-dependent polarization in the crystal itself as a consequence of optical rectification. This process gives rise to the emission of microwave radiation that is detected by a receiver and is analyzed to infer the repetition rate and intensity of the pulses. We believe that this new method may overcome some of the limitations of photodetection techniques.

  9. Tutorial on fiber-based sources for biophotonic applications

    Science.gov (United States)

    Taylor, James R.

    2016-06-01

    Fiber-based lasers and master oscillator power fiber amplifier configurations are described. These allow spectral versatility coupled with pulse width and pulse repetition rate selection in compact and efficient packages. This is enhanced through the use of nonlinear optical conversion in fibers and fiber-coupled nonlinear crystals, which can be integrated to provide all-fiber pump sources for diverse application. The advantages and disadvantages of sources based upon supercontinuum generation, stimulated Raman conversion, four-wave mixing, parametric generation and difference frequency generation, allowing spectral coverage from the UV to the mid-infrared, are considered.

  10. High-repetition-rate and high-photon-flux 70 eV high-harmonic source for coincidence ion imaging of gas-phase molecules.

    Science.gov (United States)

    Rothhardt, Jan; Hädrich, Steffen; Shamir, Yariv; Tschnernajew, Maxim; Klas, Robert; Hoffmann, Armin; Tadesse, Getnet K; Klenke, Arno; Gottschall, Thomas; Eidam, Tino; Limpert, Jens; Tünnermann, Andreas; Boll, Rebecca; Bomme, Cedric; Dachraoui, Hatem; Erk, Benjamin; Di Fraia, Michele; Horke, Daniel A; Kierspel, Thomas; Mullins, Terence; Przystawik, Andreas; Savelyev, Evgeny; Wiese, Joss; Laarmann, Tim; Küpper, Jochen; Rolles, Daniel

    2016-08-01

    Unraveling and controlling chemical dynamics requires techniques to image structural changes of molecules with femtosecond temporal and picometer spatial resolution. Ultrashort-pulse x-ray free-electron lasers have significantly advanced the field by enabling advanced pump-probe schemes. There is an increasing interest in using table-top photon sources enabled by high-harmonic generation of ultrashort-pulse lasers for such studies. We present a novel high-harmonic source driven by a 100 kHz fiber laser system, which delivers 1011 photons/s in a single 1.3 eV bandwidth harmonic at 68.6 eV. The combination of record-high photon flux and high repetition rate paves the way for time-resolved studies of the dissociation dynamics of inner-shell ionized molecules in a coincidence detection scheme. First coincidence measurements on CH3I are shown and it is outlined how the anticipated advancement of fiber laser technology and improved sample delivery will, in the next step, allow pump-probe studies of ultrafast molecular dynamics with table-top XUV-photon sources. These table-top sources can provide significantly higher repetition rates than the currently operating free-electron lasers and they offer very high temporal resolution due to the intrinsically small timing jitter between pump and probe pulses. PMID:27505779

  11. When complex is easy on the mind: Internal repetition of visual information in complex objects is a source of perceptual fluency.

    Science.gov (United States)

    Joye, Yannick; Steg, Linda; Ünal, Ayça Berfu; Pals, Roos

    2016-01-01

    Across 3 studies, we investigated whether visual complexity deriving from internally repeating visual information over many scale levels is a source of perceptual fluency. Such continuous repetition of visual information is formalized in fractal geometry and is a key-property of natural structures. In the first 2 studies, we exposed participants to 3-dimensional high-fractal versus low-fractal stimuli, respectively characterized by a relatively high versus low degree of internal repetition of visual information. Participants evaluated high-fractal stimuli as more complex and fascinating than their low-fractal counterparts. We assessed ease of processing by asking participants to solve effortful puzzles during and after exposure to high-fractal versus low-fractal stimuli. Across both studies, we found that puzzles presented during and after seeing high-fractal stimuli were perceived as the easiest ones to solve and were solved more accurately and faster than puzzles associated with the low-fractal stimuli. In Study 3, we ran the Dot Probe Procedure to rule out that the findings from Study 1 and Study 2 reflected differences in attentional bias between the high-fractal and low-fractal stimuli, rather than perceptual fluency. Overall, our findings confirm that complexity deriving from internal repetition of visual information can be easy on the mind. (PsycINFO Database Record PMID:26322692

  12. Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS)

    DEFF Research Database (Denmark)

    Lefaucheur, Jean-Pascal; André-Obadia, Nathalie; Antal, Andrea;

    2014-01-01

    A group of European experts was commissioned to establish guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS) from evidence published up until March 2014, regarding pain, movement disorders, stroke, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy......, consciousness disorders, tinnitus, depression, anxiety disorders, obsessive-compulsive disorder, schizophrenia, craving/addiction, and conversion. Despite unavoidable inhomogeneities, there is a sufficient body of evidence to accept with level A (definite efficacy) the analgesic effect of high-frequency (HF) r...

  13. Faceted Taxonomy-Based Sources

    Science.gov (United States)

    Tzitzikas, Yannis

    The objective of this chapter is to explain the underlying mathematical structure of faceted taxonomy-based sources and to provide some common notions and notations that are used in some parts of the book. Subsequently, and on the basis of the introduced formalism, this chapter describes the interaction between a user and an information source that supports dynamic taxonomies and faceted search.

  14. Repetitive Stress Injuries

    Science.gov (United States)

    ... Can I Help a Friend Who Cuts? Repetitive Stress Injuries KidsHealth > For Teens > Repetitive Stress Injuries Print ... t had any problems since. What Are Repetitive Stress Injuries? Repetitive stress injuries (RSIs) are injuries that ...

  15. Multi-Pulse Laser Wakefield Acceleration: A New Route to Efficient, High-Repetition-Rate Plasma Accelerators and High Flux Radiation Sources

    CERN Document Server

    Hooker, S M; Mangles, S P D; Tünnermann, A; Corner, L; Limpert, J; Seryi, A; Walczak, R

    2014-01-01

    Laser-driven plasma accelerators can generate accelerating gradients three orders of magnitude larger than radio-frequency accelerators and have achieved beam energies above 1 GeV in centimetre long stages. However, the pulse repetition rate and wall-plug efficiency of plasma accelerators is limited by the driving laser to less than approximately 1 Hz and 0.1% respectively. Here we investigate the prospects for exciting the plasma wave with trains of low-energy laser pulses rather than a single high-energy pulse. Resonantly exciting the wakefield in this way would enable the use of different technologies, such as fibre or thin-disc lasers, which are able to operate at multi-kilohertz pulse repetition rates and with wall-plug efficiencies two orders of magnitude higher than current laser systems. We outline the parameters of efficient, GeV-scale, 10-kHz plasma accelerators and show that they could drive compact X-ray sources with average photon fluxes comparable to those of third-generation light source but wi...

  16. High repetition rate collisional soft x-ray lasers based on grazing incidence pumping

    Energy Technology Data Exchange (ETDEWEB)

    Luther, B M; Wang, Y; Larotonda, M A; Alessi, D; Berrill, M; Rocca, J J; Dunn, J; Keenan, R; Shlyaptsev, V N

    2005-11-18

    We discuss the demonstration of gain-saturated high repetition rate table-top soft x-ray lasers producing microwatt average powers at wavelengths ranging from 13.9 to 33 nm. The results were obtained heating a pre-created plasma with a picosecond optical laser pulse impinging at grazing incidence onto a pre-created plasma. This pumping geometry increases the energy deposition efficiency of the pump beam into the gain region, making it possible to saturate soft x-ray lasers in this wavelength range with a short pulse pump energy of only 1 J at 800 nm wavelength. Results corresponding to 5 Hz repetition rate operation of gain-saturated 14.7 nm Ni-like Pd and 32.6 nm line Ne-like Ti lasers pumped by a table-top Ti:sapphire laser are reported. We also discuss results obtained using a 1 {omega} 1054 nm pre-pulse and 2{omega} 527 nm short pulse from a Nd:glass pump laser. This work demonstrates the feasibility of producing compact high average power soft x-ray lasers for applications.

  17. Chapter 5 mantram repetition: an evidence-based complementary practice for military personnel and veterans in the 21st century.

    Science.gov (United States)

    Bormann, Jill E; Weinrich, Sally; Allard, Carolyn B; Beck, Danielle; Johnson, Brian D; Holt, Lindsay Cosco

    2014-01-01

    Today in the digital age, with our advances in modern technology and communication, there are additional stressors for our military personnel and Veterans. Constant dangers exist both on and off the battlefield, unlike prior wars that had clearly-defined war zones. In addition, medical advances have assisted in saving the lives of many more gravely injured troops than ever previously possible. As the wars in Iraq and Afghanistan come to an end, large numbers of service men and women are returning home with multiple injuries. This group of Veterans has significantly higher rates of posttraumatic stress disorder (PTSD) and traumatic brain injury than ever before reported. Although existing PTSD therapies have been found to be highly effective for many Veterans, there is a substantial minority unsatisfactorily treated. Mantram repetition, an innovative, complementary, evidence-based treatment, is proving to be successful for these new Veterans. When used regularly it helps with "road rage, impatience, anger, frustration, and being out of control." A mantram is a brief, sacred word or phrase that embodies divine power or the greatest positive energy one can imagine (Easwaran, 2008a). Mantram repetition is a simple, quick, personal, portable, and private complementary practice that may be used as an adjunct to current treatments for PTSD. Growing research evidence supports mantram repetition's value for dissemination and adoption in the 21st century. This chapter summarizes Mantram Program research conducted from 2003 to 2014. It describes the health-related benefits of the Mantram Program in various populations. The current research focuses on benefits for managing psychological distress and promoting quality of life in Veterans. Future areas for research are suggested.

  18. Transdiagnostic Treatment of Co-occurrence of Anxiety and Depressive Disorders based on Repetitive Negative Thinking: A Case Series

    Directory of Open Access Journals (Sweden)

    Mehdi Akbari

    2015-11-01

    Full Text Available  Objective: The transdiagnostic cognitive behavioral treatments for treating the coexistence of anxiety and mood disorders received useful empirical supports in the recent years. However, these treatments still have moderate efficacy. Following the improvements and developments in transdiagnostic protocols and considering the importance of repetitive negative thinking as a core transdiagnostic factor in emotional disorders, this study examined a new form of transdiagnostic treatment based on Repetitive Negative Thinking (TTRNT of co-occurrence of anxiety and depressive disorders.  Methods:Treatment efficacy was assessed using single case series with multiple baselines. Three patients meeting the criteria for co-occurrence of anxiety and depressive disorders were selected using the Anxiety Disorders Interview Schedule for DSM-IV. The patients were treated individually for 12 weekly sessions. Participants completed the standardized outcome measures during the baseline, treatment and one-month follow-up. Results:At post-treatment, all participants showed significant clinical changes on a range of standardized outcome measures, and these gains were largely maintained through the one-month follow-up both in the principle and co-principal diagnosis. Conclusions:Although the results of this preliminary investigation indicated that TTRNT could be a time effective and efficient treatment for individuals with co-occurrence of anxiety and depressive disorders, further controlled clinical trials are necessary to examine this new treatment approach.

  19. RELIABILITY OF THE ONE-REPETITION MAXIMUM TEST BASED ON MUSCLE GROUP AND GENDER

    Directory of Open Access Journals (Sweden)

    Dong-il Seo

    2012-06-01

    Full Text Available The purpose of the present study was to examine the influence of muscle group location and gender on the reliability of assessing the one-repetition maximum (1RM test. Thirty healthy males (n = 15 and females (n = 15 who experienced at least 3 months of continuous resistance training during the last 2 years aged 18-35 years volunteered to participate in the study. The 1RM for the biceps curl, lat pull down, bench press, leg curl, hip flexion, triceps extension, shoulder press, low row, leg extension, hip extension, leg press and squat were measured twice by a trained professional using a standard published protocol. Biceps curl, lat pull down, bench press, leg curl, hip flexion, and squat 1RM's were measured on the first visit, then 48 hours later, subjects returned for their second visit. During their second visit, 1RM of triceps extension, shoulder press, low row, leg extension, hip extension, and leg press were measured. One week from the second visit, participants completed the 1 RM testing as previously done during the first and second visits. The third and fourth visits were separated by 48 hours as well. All four visits to the laboratory were at the same time of day. A high intraclass correlation coefficient (ICC > 0.91 was found for all exercises, independent of gender and muscle group size or location, however there was a significant interaction for muscle group location (upper body vs. lower body in females (p < 0.027. In conclusion, a standardized 1RM testing protocol with a short warm-up and familiarization period is a reliable measurement to assess muscle strength changes regardless of muscle group location or gender

  20. Generation of tunable, high repetition rate frequency combs with equalized spectra using carrier injection based silicon modulators

    Science.gov (United States)

    Nagarjun, K. P.; Selvaraja, Shankar Kumar; Supradeepa, V. R.

    2016-03-01

    High repetition-rate frequency combs with tunable repetition rate and carrier frequency are extensively used in areas like Optical communications, Microwave Photonics and Metrology. A common technique for their generation is strong phase modulation of a CW-laser. This is commonly implemented using Lithium-Niobate based modulators. With phase modulation alone, the combs have poor spectral flatness and significant number of missing lines. To overcome this, a complex cascade of multiple intensity and phase modulators are used. A comb generator on Silicon based on these principles is desirable to enable on-chip integration with other functionalities while reducing power consumption and footprint. In this work, we analyse frequency comb generation in carrier injection based Silicon modulators. We observe an interesting effect in these comb generators. Enhanced absorption accompanying carrier injection, an undesirable effect in data modulators, shapes the amplitude here to enable high quality combs from a single modulator. Thus, along with reduced power consumption to generate a specific number of lines, the complexity has also been significantly reduced. We use a drift-diffusion solver and mode solver (Silvaco TCAD) along with Soref-Bennett relations to calculate the variations in refractive indices and absorption of an optimized Silicon PIN - waveguide modulator driven by an unbiased high frequency (10 Ghz) voltage signal. Our simulations demonstrate that with a device length of 1 cm, a driving voltage of 2V and minor shaping with a passive ring-resonator filter, we obtain 37 lines with a flatness better than 5-dB across the band and power consumption an order of magnitude smaller than Lithium-Niobate modulators.

  1. High-repetition-rate and high-photon-flux 70 eV high-harmonic source for coincidence ion imaging of gas-phase molecules

    CERN Document Server

    Rothhardt, Jan; Shamir, Yariv; Tschnernajew, Maxim; Klas, Robert; Hoffmann, Armin; Tadesse, Getnet K; Klenke, Arno; Gottschall, Thomas; Eidam, Tino; Boll, Rebecca; Bomme, Cedric; Dachraoui, Hatem; Erk, Benjamin; Di Fraia, Michele; Horke, Daniel A; Kierspel, Thomas; Mullins, Terence; Przystawik, Andreas; Savelyev, Evgeny; Wiese, Joss; Laarmann, Tim; Küpper, Jochen; Rolles, Daniel; Limpert, Jens; Tünnermann, Andreas

    2016-01-01

    Unraveling and controlling chemical dynamics requires techniques to image structural changes of molecules with femtosecond temporal and picometer spatial resolution. Ultrashort-pulse x-ray free-electron lasers have significantly advanced the field by enabling advanced pump-probe schemes. There is an increasing interest in using table-top photon sources enabled by high-harmonic generation of ultrashort-pulse lasers for such studies. We present a novel high-harmonic source driven by a 100 kHz fiber laser system, which delivers 10$^{11}$ photons/s in a single 1.3 eV bandwidth harmonic at 68.6 eV. The combination of record-high photon flux and high repetition rate paves the way for time-resolved studies of the dissociation dynamics of inner-shell ionized molecules in a coincidence detection scheme. First coincidence measurements on CH$_3$I are shown and it is outlined how the anticipated advancement of fiber laser technology and improved sample delivery will, in the next step, allow pump-probe studies of ultrafas...

  2. Optimum design on thermal lensing effect of high-repetition-frequency laser based on LGS Q-switched

    Science.gov (United States)

    Li, Gang; Li, Li; Sun, Xinhua; Jin, Yezhou; Mao, Shaojuan; Wang, Yuanbo

    2014-12-01

    The thermal lensing effect of crystal is the biggest problem for the output of laser pulse with high power and high beam quality. Through the design of laser cavity, this effect can be removed a certain extent. In this paper, a high-repetition-frequency laser based on electro-optic Q-switch made of LGS is designed. Using flat-flat cavity, the purposes of simple structure and steady output are achieved. Firstly, using a LGS as Q-switched crystal, a Brewster plate as a polarizer, a xenon flash-lamp pumped 1064 nm high-repetition-frequency pulsed Nd:YAG laser with flat-flat cavity is demonstrated. Then, the stability of the laser cavity is analysed. Considering the thermal lensing effect of Nd:YAG crystal, the focal length of thermal lens is calculated. Utilizing MathCAD, the ABCD matrix of laser cavity is calculated, and the G value is obtained, that is G=0.792<1, so the laser cavity is steady. Furthermore, the distribution of light beam in the laser cavity is also simulated by using LAS-CAD, the results indicate that the laser works at stead state. Thirdly, the thermal lensing effect of Nd:YAG crystal is analysed by using LAS-CAD. The temperature and refractive index distributions of Nd:YAG crystal are simulated, the results show that the crystal can be equivalented as a lens with certain focal length. Furthermore, utilizing finite element analysis (FEA) method, the three-dimensional view of temperature field is obtained.

  3. Conducted noise analysis and protection of 45 kJ/s, ±50 kV capacitor charging power supply when interfaced with repetitive Marx based pulse power system

    Science.gov (United States)

    Naresh, P.; Patel, Ankur; Sharma, Archana

    2015-09-01

    Pulse power systems with highly dynamic loads like klystron, backward wave oscillator (BWO), and magnetron generate highly dynamic noise. This noise leads to frequent failure of controlled switches in the inverter stage of charging power supply. Designing a reliable and compatible power supply for pulse power applications is always a tricky job when charging rate is in multiples of 10 kJ/s. A ±50 kV and 45 kJ/s capacitor charging power supply based on 4th order LCLC resonant topology has been developed for a 10 Hz repetitive Marx based system. Conditions for load independent constant current and zero current switching (ZCS) are derived mathematically. Noise generated at load end due to dynamic load is tackled effectively and reduction in magnitude noise voltage is achieved by providing shielding between primary and secondary of high voltage high frequency transformer and with LCLC low pass filter. Shielding scales down the ratio between coupling capacitance (Cc) and the collector-emitter capacitance of insulated gate bi-polar transistor switch, which in turn reduces the common mode noise voltage magnitude. The proposed 4th order LCLC resonant network acts as a low pass filter for differential mode noise in the reverse direction (from load to source). Power supply has been tested repeatedly with 5 Hz repetition rate with repetitive Marx based system connected with BWO load working fine without failure of single switch in the inverter stage.

  4. A Beat Frequency RF Modulator for Generation of Low Repetition Rate Electron Microbunches for the CEBAF Polarized Source

    Energy Technology Data Exchange (ETDEWEB)

    John Musson; Reza Kazimi; Benard Poelker; Joseph Grames; John Hansknecht

    2007-06-25

    Fiber-based drive lasers now produce all of the spin-polarized electron beams at CEBAF/Jefferson Lab. The flexibility of these drive lasers, combined with the existing three-beam CEBAF photoinjector Chopper, provides a means to implement a beat frequency technique to produce long time intervals between individual electron microbunches (tens of nanoseconds) by merely varying the nominal 499 MHz drive laser frequency by < 20%. This submission describes the RF Laser modulator that uses a divider and heterodyne scheme to maintain coherence with the accelerator Master Oscillator (MO), while providing delay resolution in increments of 2ns. Some possible uses for such a beam are discussed as well as intended future development.

  5. Development of two highly sensitive forensic sex determination assays based on human DYZ1 and Alu repetitive DNA elements.

    Science.gov (United States)

    Fazi, Amanda; Gobeski, Brianne; Foran, David

    2014-11-01

    Sex determination is a critical component of forensic identification, the standard genetic method for which is detection of the single copy amelogenin gene that has differing homologues on the X and Y chromosomes. However, this assay may not be sensitive enough when DNA samples are minute or highly compromised, thus other strategies for sex determination are needed. In the current research, two ultrasensitive sexing assays, based on real-time PCR and pyrosequencing, were developed targeting the highly repetitive elements DYZ1 on the Y chromosome and Alu on the autosomes. The DYZ1/Alu strategy was compared to amelogenin for overall sensitivity based on high molecular weight and degraded DNA, followed by assaying the sex of 34 touch DNA samples and DNA from 30 hair shafts. The real-time DYZ1/Alu assay proved to be approximately 1500 times more sensitive than its amelogenin counterpart based on high molecular weight DNA, and even more sensitive when sexing degraded DNA. The pyrosequencing DYZ1/Alu assay correctly sexed 26 of the touch DNAs, compared to six using amelogenin. Hair shaft DNAs showed equally improved sexing results using the DYZ1/Alu assays. Overall, both DYZ1/Alu assays were far more sensitive and accurate than was the amelogenin assay, and thus show great utility for sexing poor quality and low quantity DNA evidence. PMID:25168471

  6. Demonstration of a time-resolved x-ray scattering instrument utilizing the full-repetition rate of x-ray pulses at the Pohang Light Source

    Science.gov (United States)

    Jo, Wonhyuk; Eom, Intae; Landahl, Eric C.; Lee, Sooheyong; Yu, Chung-Jong

    2016-03-01

    We report on the development of a new experimental instrument for time-resolved x-ray scattering (TRXS) at the Pohang Light Source (PLS-II). It operates with a photon energy ranging from 5 to 18 keV. It is equipped with an amplified Ti:sappahire femtosecond laser, optical diagnostics, and laser beam delivery for pump-probe experiments. A high-speed single-element detector and high trigger-rate oscilloscope are used for rapid data acquisition. While this instrument is capable of measuring sub-nanosecond dynamics using standard laser pump/x-ray probe techniques, it also takes advantage of the dense 500 MHz standard fill pattern in the PLS-II storage ring to efficiently record nano-to-micro-second dynamics simultaneously. We demonstrate this capability by measuring both the (fast) impulsive strain and (slower) thermal recovery dynamics of a crystalline InSb sample following intense ultrafast laser excitation. Exploiting the full repetition rate of the storage ring results in a significant improvement in data collection rates compared to conventional bunch-tagging methods.

  7. Superradiant THz undulator radiation source based on a superconducting photo-injector

    Science.gov (United States)

    Wen, Xiaodong; Huang, Senlin; Lin, Lin; Wang, Fang; Zhu, Feng; Feng, Liwen; Yang, Limin; Wang, Zhiwen; Fan, Peiliang; Hao, Jiankui; Quan, Shengwen; Liu, Kexin; Chen, Jia-er

    2016-06-01

    Superconducting radio frequency accelerators are used to produce terahertz (THz) radiation pulses with a high repetition rate. In this study, a compact high repetition rate THz radiation source has been developed based on a DC-SRF photo-injector through velocity bunching at Peking University. This compact THz source can theoretically generate approximately 1 W of superradiant THz radiation, with a repetition rate of 16.25 MHz and a frequency that can be tuned from 0.24 THz to 0.42 THz by varying the electron beam energy from 2.4 MeV to 3.1 MeV. Simulation results indicate that the asymmetrical longitudinal distribution of electrons in each bunch caused by velocity bunching increases the THz power by about 2 orders at wavelength within 400-700 μm. Experimental measurements are consistent with the calculation results when propagation loss is considered. This paper presents the system description, simulation, and experiments of the high repetition rate THz source.

  8. [Homologous Analysis Using Repetitive-sequence-based PCR Typing of Exfoliative Toxin-producing Staphylococcus aureus Isolated from Our Hospital].

    Science.gov (United States)

    Miyamoto, Hitoshi; Murakami, Shinobu; Nishimiya, Tatsuya; Suemori, Koichiro; Tauchi, Hisamichi

    2015-05-01

    We examined staphylococcal coagulase types and homologous analysis using the DiversiLab repetitive-sequence-based PCR system in exfoliative toxin (ET)-producing Staphylococcus aureus. Twenty-two isolates (17 methicillin-sensitive Staphylococcus aureus (MSSA) and 5 methicillin-resistant Staphylococcus aureus (MRSA) isolates) obtained in our hospital from January 2012 and December 2013 were used. Three groups were classified according to the coagulase types and serotypes of ET. The first group (4 MSSA) showed coagulase type I and ET-A, and the second group (3 MSSA and 2 MRSA) showed coagulase type I and ET-B. The third group (10 MSSA and 3 MRSA) showed coagulase type V and ET-B. An analysis by DiversiLab demonstrated that homology was high in both the first and second groups. The homogenousness was high among the third group isolates except for the ocular isolates. In our hospital, three important groups were present according to a coagulase type and an ET type, and the homology of ocular isolates could be different from other materials isolates.

  9. A strategy of gene overexpression based on tandem repetitive promoters in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Li Mingji

    2012-02-01

    Full Text Available Abstract Background For metabolic engineering, many rate-limiting steps may exist in the pathways of accumulating the target metabolites. Increasing copy number of the desired genes in these pathways is a general method to solve the problem, for example, the employment of the multi-copy plasmid-based expression system. However, this method may bring genetic instability, structural instability and metabolic burden to the host, while integrating of the desired gene into the chromosome may cause inadequate transcription or expression. In this study, we developed a strategy for obtaining gene overexpression by engineering promoter clusters consisted of multiple core-tac-promoters (MCPtacs in tandem. Results Through a uniquely designed in vitro assembling process, a series of promoter clusters were constructed. The transcription strength of these promoter clusters showed a stepwise enhancement with the increase of tandem repeats number until it reached the critical value of five. Application of the MCPtacs promoter clusters in polyhydroxybutyrate (PHB production proved that it was efficient. Integration of the phaCAB genes with the 5CPtacs promoter cluster resulted in an engineered E.coli that can accumulate 23.7% PHB of the cell dry weight in batch cultivation. Conclusions The transcription strength of the MCPtacs promoter cluster can be greatly improved by increasing the tandem repeats number of the core-tac-promoter. By integrating the desired gene together with the MCPtacs promoter cluster into the chromosome of E. coli, we can achieve high and stale overexpression with only a small size. This strategy has an application potential in many fields and can be extended to other bacteria.

  10. Monitoring transmission routes of Listeria spp. in smoked salmon production with repetitive element sequence-based PCR techniques.

    Science.gov (United States)

    Zunabovic, M; Domig, K J; Pichler, I; Kneifel, W

    2012-03-01

    Various techniques have been used for tracing the transmission routes of Listeria species and for the assessment of hygiene standards in food processing plants. The potential of repetitive element sequence-based PCR (Rep-PCR) methods (GTG₅ and REPI + II) for the typing of Listeria isolates (n = 116), including Listeria monocytogenes (n = 46), was evaluated in a particular situation arising from the relocation of a company producing cold-smoked salmon. Pulsed-field gel electrophoresis (PFGE) using three restriction enzymes (ApaI, AscI, and SmaI) was used for comparison. Identical transmission scenarios among two companies could be identified by cluster analysis of L. monocytogenes isolates that were indistinguishable by both Rep-PCR and PFGE. The calculated diversity index (DI) indicates that Rep-PCR subtyping of Listeria species with primer sets GTG₅ and REPI + II has a lower discrimination power than does PFGE. When concatenated Rep-PCR cluster analysis was used, the DI increased from 0.934 (REPI + II) and 0.923 (GTG₅) to 0.956. The discrimination power of this method was similar to that of PFGE typing based on restriction enzyme Apa I (DI = 0.955). Listeria welshimeri may be useful as an indicator for monitoring smoked salmon processing environments. Rep-PCR meets the expectations of a reasonable, fast, and low-cost molecular subtyping method for the routine monitoring of Listeria species. The discriminatory power as characterized by the DI sufficiently quantifies the probability of unrelated isolates being characterized as different subtypes. Therefore, Rep-PCR typing based on two primer systems (GTG₅ and REPI + II) may be a useful tool for monitoring industrial hygiene.

  11. A review of laser and synchrotron based X-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. [Paris-Sud Univ., Orsay (France). LSAI; Key, M.H. [Paris-Sud Univ., Orsay (France). LSAI; Lawrence Livermore National Lab., CA (United States)

    2001-07-01

    The rapid development of laser technology and related progress in research using lasers is shifting the boundaries where laser based sources are preferred over other light sources particularly in the XUV and X-ray spectral region. Laser based sources have exceptional capability for short pulse and high brightness and with improvements in high repetition rate pulsed operation, such sources are also becoming more interesting for their average power capability. This study presents an evaluation of the current capabilities and near term future potential of laser based light sources and summarises, for the purpose of comparison, the characteristics and near term prospects of sources based on synchrotron radiation and free electron lasers. Relative comparisons are given within charts of peak brightness. (orig.)

  12. Short-time X-ray diffraction with an efficient-optimized, high repetition-rate laser-plasma X-ray-source

    International Nuclear Information System (INIS)

    This thesis deals with the production and application of ultrashort X-ray pulses. In the beginning different possibilities for the production of X-ray pulses with pulse durations of below one picosecond are presented, whereby the main topic lies on the so called laser-plasma X-ray sources with high repetition rate. In this case ultrashort laser pulses are focused on a metal, so that in the focus intensities of above 1016 W/cm2 dominate. In the ideal case in such way ultrafast electrons are produced, which are responsible for line radiation. In these experiments titanium Kα radiation is produced, thes photons possess an energy of 4.51 keV. For the efficient production of line radiation here the Ti:Sa laser is optimized in view of the laser energy and the pulse shape and the influence of the different parameters on the Kα production systematically studied. The influences of laser intensity, system-conditioned pre-pulses and of phase modulation are checked. It turns out that beside the increasement of the Kα radiation by a suited laser intensity a reduction of the X-ray background radiation is of deciding importance for the obtaining of clear diffraction images. This background radiation is mainly composed of bremsstrahlung. It can be suppressed by the avoidance of intrinsic pre-pulses and by means of 2nd-order phase modulation. By means of optical excitation and X-ray exploration experiments the production of acoustic waves after ultrashort optical excitation in a 150 nm thick Ge(111) film on Si(111) is studied. These acoustic waves are driven by thermal (in this time scale time-independent) and electronic (time dependent) pressure amounts. As essential results it turns out that the relative amount of the electronic pressure increases with decreasing excitation density

  13. Genotypic Characterization of Escherichia coli O157:H7 Isolates from Different Sources in the North-West Province, South Africa, Using Enterobacterial Repetitive Intergenic Consensus PCR Analysis

    Directory of Open Access Journals (Sweden)

    Collins Njie Ateba

    2014-05-01

    Full Text Available In many developing countries, proper hygiene is not strictly implemented when animals are slaughtered and meat products become contaminated. Contaminated meat may contain Escherichia coli (E. coli O157:H7 that could cause diseases in humans if these food products are consumed undercooked. In the present study, a total of 94 confirmed E. coli O157:H7 isolates were subjected to the enterobacterial repetitive intergenic consensus (ERIC polymerase chain reaction (PCR typing to generate genetic fingerprints. The ERIC fragments were resolved by electrophoresis on 2% (w/v agarose gels. The presence, absence and intensity of band data were obtained, exported to Microsoft Excel (Microsoft Office 2003 and used to generate a data matrix. The unweighted pair group method with arithmetic mean (UPGMA and complete linkage algorithms were used to analyze the percentage of similarity and matrix data. Relationships between the various profiles and/or lanes were expressed as dendrograms. Data from groups of related lanes were compiled and reported on cluster tables. ERIC fragments ranged from one to 15 per isolate, and their sizes varied from 0.25 to 0.771 kb. A large proportion of the isolates produced an ERIC banding pattern with three duplets ranging in sizes from 0.408 to 0.628 kb. Eight major clusters (I–VIII were identified. Overall, the remarkable similarities (72% to 91% between the ERIC profiles for the isolate from animal species and their corresponding food products indicated some form of contamination, which may not exclude those at the level of the abattoirs. These results reveal that ERIC PCR analysis can be reliable in comparing the genetic profiles of E. coli O157:H7 from different sources in the North-West Province of South Africa.

  14. Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

    Science.gov (United States)

    Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

    2016-04-01

    We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results. PMID:26382131

  15. Estimations of One Repetition Maximum and Isometric Peak Torque in Knee Extension Based on the Relationship Between Force and Velocity.

    Science.gov (United States)

    Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo

    2016-04-01

    We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results.

  16. Repetition, Power Imbalance, and Intentionality: Do These Criteria Conform to Teenagers' Perception of Bullying? A Role-Based Analysis

    Science.gov (United States)

    Cuadrado-Gordillo, Isabel

    2012-01-01

    The criteria that researchers use to classify aggressive behaviour as bullying are "repetition", "power imbalance", and "intent to hurt". However, studies that have analyzed adolescents' perceptions of bullying find that most adolescents do not simultaneously consider these three criteria. This paper examines adolescents' perceptions of bullying…

  17. High brightness EUV sources based on laser plasma at using droplet liquid metal target

    Science.gov (United States)

    Vinokhodov, A. Yu; Krivokorytov, M. S.; Sidelnikov, Yu V.; Krivtsun, V. M.; Medvedev, V. V.; Koshelev, K. N.

    2016-05-01

    We present the study of a source of extreme ultraviolet (EUV) radiation based on laser plasma generated due to the interaction of radiation from a nanosecond Nd : YAG laser with a liquidmetal droplet target consisting of a low-temperature eutectic indium–tin alloy. The generator of droplets is constructed using a commercial nozzle and operates on the principle of forced capillary jet decomposition. Long-term spatial stability of the centre-of-mass position of the droplet with the root-mean-square deviation of ~0.5 μm is demonstrated. The use of a low-temperature working substance instead of pure tin increases the reliability and lifetime of the droplet generator. For the time- and space-averaged power density of laser radiation on the droplet target 4 × 1011 W cm-2 and the diameter of radiating plasma ~80 μm, the mean efficiency of conversion of laser energy into the energy of EUV radiation at 13.5 +/- 0.135 nm equal to 2.3% (2π sr)-1 is achieved. Using the doublepulse method, we have modelled the repetitively pulsed regime of the source operation and demonstrated the possibility of its stable functioning with the repetition rate up to 8 kHz for the droplet generation repetition rate of more than 32 kHz, which will allow the source brightness to be as large as ~0.96 kW (mm2 sr)-1.

  18. Roles of repetitive sequences

    Energy Technology Data Exchange (ETDEWEB)

    Bell, G.I.

    1991-12-31

    The DNA of higher eukaryotes contains many repetitive sequences. The study of repetitive sequences is important, not only because many have important biological function, but also because they provide information on genome organization, evolution and dynamics. In this paper, I will first discuss some generic effects that repetitive sequences will have upon genome dynamics and evolution. In particular, it will be shown that repetitive sequences foster recombination among, and turnover of, the elements of a genome. I will then consider some examples of repetitive sequences, notably minisatellite sequences and telomere sequences as examples of tandem repeats, without and with respectively known function, and Alu sequences as an example of interspersed repeats. Some other examples will also be considered in less detail.

  19. A repetitively pulsed xenon chloride excimer laser with all ferrite magnetic cores (AFMC) based all solid state exciter

    Science.gov (United States)

    Benerji, N. S.; Varshnay, N. K.; Ghodke, D. V.; Singh, A.

    2016-10-01

    Performance of repetitively pulsed xenon chloride excimer laser (λ~308 nm) with solid state pulser consisting of magnetic pulse compression circuit (MPC) using all ferrite magnetic cores (AFMC) is reported. Laser system suitable for 100 Hz operation with inbuilt pre-ionizer, compact gas circulation and cooling has been developed and presented. In this configuration, high voltage pulses of ~8 μs duration are compressed to ~100 ns by magnetic pulse compression circuit with overall compression factor of ~80. Pulse energy of ~18 J stored in the primary capacitor is transferred to the laser head with an efficiency of ~85% compared to ~70% that is normally achieved in such configurations using annealed met-glass core. This is a significant improvement of about 21%. Maximum output laser pulse energy of ~100 mJ was achieved at repetition rate of 100 Hz with a typical pulse to pulse energy stability of ±5% and laser pulse energy of 150 mJ was generated at low rep-rate of ~40 Hz. This exciter uses a low current and low voltage solid state switch (SCR) that replaces high voltage and high current switch i. e, thyratron completely. The use of solid state exciter in turn reduces electromagnetic interference (EMI) effects particularly in excimer lasers where high EMI is present due to high di/dt. The laser is focused on a thin copper sheet for generation of micro-hole and the SEM image of the generated micro hole shows the energy stability of the laser at high repetition rate operation. Nearly homogeneous, regular and well developed xenon chloride (XeCl) laser beam spot was achieved using the laser.

  20. A Compact, Transportable, Microchip-Based System for High Repetition Rate Production of Bose-Einstein Condensates

    CERN Document Server

    Farkas, Daniel M; Salim, Evan A; Segal, Stephen R; Squires, Matthew B; Anderson, Dana Z

    2009-01-01

    We present a compact, transportable system that produces Bose-Einstein condensates (BECs) near the surface of an integrated atom microchip. The system occupies a volume of 0.4 m^3 and operates at a repetition rate as high as 0.3 Hz. Evaporative cooling in a chip trap with trap frequencies of several kHz leads to nearly pure condensates containing 1.9x10^4 87Rb atoms. Partial condensates are observed at a temperature of 1.58(8) \\mu K, close to the theoretical transition temperature of 1.1 \\mu K.

  1. Repetition and Translation Shifts

    Directory of Open Access Journals (Sweden)

    Simon Zupan

    2006-06-01

    Full Text Available Repetition manifests itself in different ways and at different levels of the text. The first basic type of repetition involves complete recurrences; in which a particular textual feature repeats in its entirety. The second type involves partial recurrences; in which the second repetition of the same textual feature includes certain modifications to the first occurrence. In the article; repetitive patterns in Edgar Allan Poe’s short story “The Fall of the House of Usher” and its Slovene translation; “Konec Usherjeve hiše”; are compared. The author examines different kinds of repetitive patterns. Repetitions are compared at both the micro- and macrostructural levels. As detailed analyses have shown; considerable microstructural translation shifts occur in certain types of repetitive patterns. Since these are not only occasional; sporadic phenomena; but are of a relatively high frequency; they reduce the translated text’s potential for achieving some of the gothic effects. The macrostructural textual property particularly affected by these shifts is the narrator’s experience as described by the narrative; which suffers a reduction in intensity.

  2. Electron Source based on Superconducting RF

    Science.gov (United States)

    Xin, Tianmu

    High-bunch-charge photoemission electron-sources operating in a Continuous Wave (CW) mode can provide high peak current as well as the high average current which are required for many advanced applications of accelerators facilities, for example, electron coolers for hadron beams, electron-ion colliders, and Free-Electron Lasers (FELs). Superconducting Radio Frequency (SRF) has many advantages over other electron-injector technologies, especially when it is working in CW mode as it offers higher repetition rate. An 112 MHz SRF electron photo-injector (gun) was developed at Brookhaven National Laboratory (BNL) to produce high-brightness and high-bunch-charge bunches for electron cooling experiments. The gun utilizes a Quarter-Wave Resonator (QWR) geometry for a compact structure and improved electron beam dynamics. The detailed RF design of the cavity, fundamental coupler and cathode stalk are presented in this work. A GPU accelerated code was written to improve the speed of simulation of multipacting, an important hurdle the SRF structure has to overcome in various locations. The injector utilizes high Quantum Efficiency (QE) multi-alkali photocathodes (K2CsSb) for generating electrons. The cathode fabrication system and procedure are also included in the thesis. Beam dynamic simulation of the injector was done with the code ASTRA. To find the optimized parameters of the cavities and beam optics, the author wrote a genetic algorithm Python script to search for the best solution in this high-dimensional parameter space. The gun was successfully commissioned and produced world record bunch charge and average current in an SRF photo-injector.

  3. Control System Design of Shunt Active Power Filter Based on Active Disturbance Rejection and Repetitive Control Techniques

    Directory of Open Access Journals (Sweden)

    Le Ge

    2014-01-01

    Full Text Available To rely on joint active disturbance rejection control (ADRC and repetitive control (RC, in this paper, a compound control law for active power filter (APF current control system is proposed. According to the theory of ADRC, the uncertainties in the model and from the circumstance outside are considered as the unknown disturbance to the system. The extended state observer can evaluate the unknown disturbance. Next, RC is introduced into current loop to improve the steady characteristics. The ADRC is used to get a good dynamic performance, and RC is used to get a good static performance. A good simulation result is got through choosing and changing the parameters, and the feasibility, adaptability, and robustness of the control are testified by this result.

  4. Circuit considerations for repetitive railguns

    Energy Technology Data Exchange (ETDEWEB)

    Honih, E.M.

    1986-01-01

    Railgun electromagnetic launchers have significant military and scientific potential. They provide direct conversion of electrical energy to projectile kinetic energy, and they offer the hope of achieving projectile velocities greatly exceeding the limits of conventional guns. With over 10 km/sec already demonstrated, railguns are attracting attention for tactical and strategic weapons systems and for scientific equation-of-state research. The full utilization of railguns will require significant improvements in every aspect of system design - projectile, barrel, and power source - to achieve operation on a large scale. This paper will review fundamental aspects of railguns, with emphasis on circuit considerations and repetitive operation.

  5. Nanomaterial-based x-ray sources

    Science.gov (United States)

    Cole, Matthew T.; Parmee, R. J.; Milne, William I.

    2016-02-01

    Following the recent global excitement and investment in the emerging, and rapidly growing, classes of one and two-dimensional nanomaterials, we here present a perspective on one of the viable applications of such materials: field electron emission based x-ray sources. These devices, which have a notable history in medicine, security, industry and research, to date have almost exclusively incorporated thermionic electron sources. Since the middle of the last century, field emission based cathodes were demonstrated, but it is only recently that they have become practicable. We outline some of the technological achievements of the past two decades, and describe a number of the seminal contributions. We explore the foremost market hurdles hindering their roll-out and broader industrial adoption and summarise the recent progress in miniaturised, pulsed and multi-source devices.

  6. Nanomaterial-based x-ray sources.

    Science.gov (United States)

    Cole, Matthew T; Parmee, R J; Milne, William I

    2016-02-26

    Following the recent global excitement and investment in the emerging, and rapidly growing, classes of one and two-dimensional nanomaterials, we here present a perspective on one of the viable applications of such materials: field electron emission based x-ray sources. These devices, which have a notable history in medicine, security, industry and research, to date have almost exclusively incorporated thermionic electron sources. Since the middle of the last century, field emission based cathodes were demonstrated, but it is only recently that they have become practicable. We outline some of the technological achievements of the past two decades, and describe a number of the seminal contributions. We explore the foremost market hurdles hindering their roll-out and broader industrial adoption and summarise the recent progress in miniaturised, pulsed and multi-source devices. PMID:26807781

  7. High-power beam-based coherently enhanced THz radiation source

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuelin; /Argonne; Sun, Yin-E; /Argonne /Fermilab; Kim, Kwang-Je; /Argonne

    2008-08-01

    We propose a compact Smith-Purcell radiation device that can potentially generate high average power THz radiation with high conversion efficiency. The source is based on a train of short electron bunches from an rf photoemission gun at an energy of a few MeV. Particle tracking simulation and analysis show that, with a beam current of 1 mA, it is feasible to generate hundreds of watts of narrow-band THz radiation at a repetition rate of 1 MHz.

  8. Repetition frequency scaling of an all-polarization maintaining erbium-doped mode-locked fiber laser based on carbon nanotubes saturable absorber

    Science.gov (United States)

    Sotor, J.; Sobon, G.; Jagiello, J.; Lipinska, L.; Abramski, K. M.

    2015-04-01

    We demonstrate an all-polarization maintaining (PM), mode-locked erbium (Er)-doped fiber laser based on a carbon nanotubes (CNT) saturable absorber (SA). The laser resonator was maximally simplified by using only one passive hybrid component and a pair of fiber connectors with deposited CNTs. The repetition frequency (Frep) of such a cost-effective and self-starting mode-locked laser was scaled from 54.3 MHz to 358.6 MHz. The highest Frep was obtained when the total cavity length was shortened to 57 cm. The laser allows ultrashort pulse generation with the duration ranging from 240 fs to 550 fs. Because the laser components were based on PM fibers the laser was immune to the external perturbations and generated laniary polarized light with the degree of polarization (DOP) of 98.7%.

  9. MEMS-based IR-sources

    Science.gov (United States)

    Weise, Sebastian; Steinbach, Bastian; Biermann, Steffen

    2016-03-01

    The series JSIR350 sources are MEMS based infrared emitters. These IR sources are characterized by a high radiation output. Thus, they are excellent for NDIR gas analysis and are ideally suited for using with our pyro-electric or thermopile detectors. The MEMS chips used in Micro-Hybrid's infrared emitters consist of nano-amorphous carbon (NAC). The MEMS chips are produced in the USA. All Micro-Hybrid Emitter are designed and specified to operate up to 850°C. The improvements we have made in the source's packaging enable us to provide IR sources with the best performance on the market. This new technology enables us to seal the housings of infrared radiation sources with soldered infrared filters or windows and thus cause the parts to be impenetrable to gases. Micro-Hybrid provide various ways of adapting our MEMS based infrared emitter JSIR350 to customer specifications, like specific burn-in parameters/characteristic, different industrial standard housings, producible with customized cap, reflector or pin-out.

  10. Cyclotron-based neutron source for BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Mitsumoto, T.; Yajima, S.; Tsutsui, H.; Ogasawara, T.; Fujita, K. [Sumitomo Heavy Industries, Ltd (Japan); Tanaka, H.; Sakurai, Y.; Maruhashi, A. [Kyoto University Research Reactor Institute (Japan)

    2013-04-19

    Kyoto University Research Reactor Institute (KURRI) and Sumitomo Heavy Industries, Ltd. (SHI) have developed a cyclotron-based neutron source for Boron Neutron Capture Therapy (BNCT). It was installed at KURRI in Osaka prefecture. The neutron source consists of a proton cyclotron named HM-30, a beam transport system and an irradiation and treatment system. In the cyclotron, H- ions are accelerated and extracted as 30 MeV proton beams of 1 mA. The proton beams is transported to the neutron production target made by a beryllium plate. Emitted neutrons are moderated by lead, iron, aluminum and calcium fluoride. The aperture diameter of neutron collimator is in the range from 100 mm to 250 mm. The peak neutron flux in the water phantom is 1.8 Multiplication-Sign 109 neutrons/cm{sup 2}/sec at 20 mm from the surface at 1 mA proton beam. The neutron source have been stably operated for 3 years with 30 kW proton beam. Various pre-clinical tests including animal tests have been done by using the cyclotron-based neutron source with {sup 10}B-p-Borono-phenylalanine. Clinical trials of malignant brain tumors will be started in this year.

  11. Open Source GIS based integrated watershed management

    Science.gov (United States)

    Byrne, J. M.; Lindsay, J.; Berg, A. A.

    2013-12-01

    Optimal land and water management to address future and current resource stresses and allocation challenges requires the development of state-of-the-art geomatics and hydrological modelling tools. Future hydrological modelling tools should be of high resolution, process based with real-time capability to assess changing resource issues critical to short, medium and long-term enviromental management. The objective here is to merge two renowned, well published resource modeling programs to create an source toolbox for integrated land and water management applications. This work will facilitate a much increased efficiency in land and water resource security, management and planning. Following an 'open-source' philosophy, the tools will be computer platform independent with source code freely available, maximizing knowledge transfer and the global value of the proposed research. The envisioned set of water resource management tools will be housed within 'Whitebox Geospatial Analysis Tools'. Whitebox, is an open-source geographical information system (GIS) developed by Dr. John Lindsay at the University of Guelph. The emphasis of the Whitebox project has been to develop a user-friendly interface for advanced spatial analysis in environmental applications. The plugin architecture of the software is ideal for the tight-integration of spatially distributed models and spatial analysis algorithms such as those contained within the GENESYS suite. Open-source development extends knowledge and technology transfer to a broad range of end-users and builds Canadian capability to address complex resource management problems with better tools and expertise for managers in Canada and around the world. GENESYS (Generate Earth Systems Science input) is an innovative, efficient, high-resolution hydro- and agro-meteorological model for complex terrain watersheds developed under the direction of Dr. James Byrne. GENESYS is an outstanding research and applications tool to address

  12. Obtaining useful information from expert based sources.

    OpenAIRE

    Slawson, D. C.; Shaughnessy, A. F.

    1997-01-01

    Clinicians rely heavily on expert based systems-consultation with colleagues, journal reviews and textbooks, and continuing education activities-to obtain new information. The usefulness of sources such as these depends on the relevance and validity of the information and the work it takes to obtain it. Useful information can be distinguished from the useless by asking three questions: Does the information focus on an outcome that my patients care about? Is the issue common to my practice, an...

  13. Measuring Modularity in Open Source Code Bases

    Directory of Open Access Journals (Sweden)

    Roberto Milev

    2009-03-01

    Full Text Available Modularity of an open source software code base has been associated with growth of the software development community, the incentives for voluntary code contribution, and a reduction in the number of users who take code without contributing back to the community. As a theoretical construct, modularity links OSS to other domains of research, including organization theory, the economics of industry structure, and new product development. However, measuring the modularity of an OSS design has proven difficult, especially for large and complex systems. In this article, we describe some preliminary results of recent research at Carleton University that examines the evolving modularity of large-scale software systems. We describe a measurement method and a new modularity metric for comparing code bases of different size, introduce an open source toolkit that implements this method and metric, and provide an analysis of the evolution of the Apache Tomcat application server as an illustrative example of the insights gained from this approach. Although these results are preliminary, they open the door to further cross-discipline research that quantitatively links the concerns of business managers, entrepreneurs, policy-makers, and open source software developers.

  14. Soft-X-Ray Projection Lithography Using a High-Repetition-Rate Laser-Induced X-Ray Source for Sub-100 Nanometer Lithography Processes

    NARCIS (Netherlands)

    E. Louis,; F. Bijkerk,; Shmaenok, L.; Voorma, H. J.; van der Wiel, M. J.; Schlatmann, R.; Verhoeven, J.; van der Drift, E. W. J. M.; Romijn, J.; Rousseeuw, B. A. C.; Voss, F.; Desor, R.; Nikolaus, B.

    1993-01-01

    In this paper we present the status of a joint development programme on soft x-ray projection lithography (SXPL) integrating work on high brightness laser plasma sources. fabrication of multilayer x-ray mirrors. and patterning of reflection masks. We are in the process of optimization of a laser-pla

  15. Source extension based on ε-entropy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian; YU Sheng-sheng; ZHOU Jing-li; ZHENG Xin-wei

    2005-01-01

    It is known by entropy theory that image is a source correlated with a certain characteristic of probability. The entropy rate of the source and ? entropy (rate-distortion function theory) are the information content to identify the characteristics of video images, and hence are essentially related with video image compression. They are fundamental theories of great significance to image compression, though impossible to be directly turned into a compression method. Based on the entropy theory and the image compression theory, by the application of the rate-distortion feature mathematical model and Lagrange multipliers to some theoretical problems in the H.264 standard, this paper presents a new the algorithm model of coding rate-distortion. This model is introduced into complete test on the capability of the test model of JM61e (JUT Test Model). The result shows that the speed of coding increases without significant reduction of the rate-distortion performance of the coder.

  16. SOURCE CODE RETRIEVAL USING SEQUENCE BASED SIMILARITY

    Directory of Open Access Journals (Sweden)

    Yoshihisa Udagawa

    2013-07-01

    Full Text Available Duplicate code adversely affects the quality of software systems and hence should be detected. We discuss an approach that improves source code retrieval using structural information of source code. A lexical parser is developed to extract control statements and method identifiers from Java programs. We propose a similarity measure that is defined by the ratio of the number of sequential fully matching statements to the number of sequential partially matching statements. The defined similarity measure is an extension of the set-based Sorensen-Dice similarity index. This research primarily contributes to the development of a similarity retrieval algorithm that derives meaningful search conditions from a given sequence, and then performs retrieval using all derived conditions. Experiments show that our retrieval model shows an improvement of up to 90.9% over other retrieval models relative to the number of retrieved methods.

  17. Source Code Retrieval Using Sequence Based Similarity

    Directory of Open Access Journals (Sweden)

    Yoshihisa Udagawa

    2013-07-01

    Full Text Available Duplicate code adversely affects the quality of software systems and hence should be detected. We discussan approach that improves source code retrieval using structural information of source code. A lexicalparser is developed to extract control statements and method identifiers from Java programs. We propose asimilarity measure that is defined by the ratio ofthe number of sequential fully matching statementsto thenumber of sequential partially matching statements.The defined similarity measure is an extension oftheset-based Sorensen-Dice similarity index. This research primarily contributes to the development of asimilarity retrieval algorithm that derives meaningful search conditions from a given sequence, and thenperforms retrieval using all derived conditions. Experiments show that our retrieval model shows animprovement of up to 90.9% over other retrieval models relative to the number of retrieved methods.

  18. Time-Series Analysis of Daily Changes in Mindfulness, Repetitive Thinking, and Depressive Symptoms During Mindfulness-Based Treatment

    NARCIS (Netherlands)

    Snippe, Evelien; Bos, E.H.; Ploeg, van der K.M.; Sanderman, R.; Fleer, J.; Schroevers, M.J.

    2015-01-01

    Mindfulness and ruminative thinking have been shown to mediate the effects of mindfulness-based treatments on depressive symptoms. Yet, the dynamic interplay between these variables in daily life during mindfulness-based treatment has received little attention. The present study focuses on the seque

  19. Plasma-based EUV light source

    Science.gov (United States)

    Shumlak, Uri; Golingo, Raymond; Nelson, Brian A.

    2010-11-02

    Various mechanisms are provided relating to plasma-based light source that may be used for lithography as well as other applications. For example, a device is disclosed for producing extreme ultraviolet (EUV) light based on a sheared plasma flow. The device can produce a plasma pinch that can last several orders of magnitude longer than what is typically sustained in a Z-pinch, thus enabling the device to provide more power output than what has been hitherto predicted in theory or attained in practice. Such power output may be used in a lithography system for manufacturing integrated circuits, enabling the use of EUV wavelengths on the order of about 13.5 nm. Lastly, the process of manufacturing such a plasma pinch is discussed, where the process includes providing a sheared flow of plasma in order to stabilize it for long periods of time.

  20. Source Code Generator Based on Dynamic Frames

    Directory of Open Access Journals (Sweden)

    Danijel Radošević

    2011-06-01

    Full Text Available Normal 0 21 false false false HR X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Obična tablica"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} This paper presents the model of source code generator based on dynamic frames. The model is named as the SCT model because if its three basic components: Specification (S, which describes the application characteristics, Configuration (C, which describes the rules for building applications, and Templates (T, which refer to application building blocks. The process of code generation dynamically creates XML frames containing all building elements (S, C ant T until final code is produced. This approach is compared to existing XVCL frames based model for source code generating. The SCT model is described by both XML syntax and the appropriate graphical elements. The SCT model is aimed to build complete applications, not just skeletons. The main advantages of the presented model are its textual and graphic description, a fully configurable generator, and the reduced overhead of the generated source code. The presented SCT model is shown on development of web application example in order to demonstrate its features and justify our design choices.

  1. Power scheduling of distributed estimation in sensor networks with repetition coding

    OpenAIRE

    Zhang, Li; Cui, Tao; Ho, Tracey; Zhang, Xian-Da

    2010-01-01

    This paper considers the optimal power scheduling for the distributed estimation of a source parameter using quantized samples of noisy sensor observations in a wireless sensor network (WSN). Repetition codes are used to transmit quantization bits of sensor observations to achieve unequal error protection, and a quasi-best linear unbiased estimate is constructed to estimate the source parameter at the fusion center (FC). Based on the adopted distributed estimation scheme (DES), we optimize th...

  2. MIMICRY, DIFFERENCE AND REPETITION

    Directory of Open Access Journals (Sweden)

    Marcelo Mendes de Souza

    2008-07-01

    Full Text Available This article addresses Homi K. Bhabha’s concept of mimicry in a broader context, other than that of cultural studies and post-colonial studies, bringing together other concepts, such as that of Gilles Deleuze in Difference and repetition, among other texts, and other names, such as Silviano Santiago, Jorge Luís Borges, Franz Kafka and Giorgio Agamben. As a partial conclusion, the article intends to oppose Bhabha’s freudian-marxist view to Five propositions on Psychoanalysis (1973, Gilles Deleuze’s text about Psychoanalysis published right after his book The Anti-Oedipus.

  3. Evolutionary Game Theoretic Modeling and Repetition of Media Distributed Shared in P2P-Based VANET

    OpenAIRE

    2014-01-01

    A significant challenge in vehicular networks is to efficiently provide multimedia services with the constraints of limited resources, high mobility, opportunistic contact, and service time requirements. In order to guarantee the vehicle user satisfaction of multimedia service, with the proliferation of the distributed peer-to-peer (P2P) cooperative transmission technologies, P2P-based VANET has recently received a substantial amount of interest. Using the P2P services thought and at the same...

  4. Operation of a high repetition rate intense ion beam diode

    International Nuclear Information System (INIS)

    A magnetically insulated diode has been developed that is capable of pulsing at high repetition rate for short bursts. This diode has a plasma-anode ion source which originates as an annular puff of H2 or some other gas. The gas puff is preionized and then inductively broken down by a 1 μs rise time magnetic field coil. This same field coil magnetically drives the resulting plasma toward a magnetically insulated acceleration gap. Finally, a ∼ 100 kV, 20--40 kA, approx-lt 100 ns acceleration voltage pulse is applied to the gap to generate the beam. The annular plasma has a mean radius of 8.5 cm, and the ion beam is extracted from an area of approx-lt 200 cm2. The pulsed power systems that drive this diode at high repetition rates are based upon saturable inductor switching. The anode plasma's temperature and density, as measured by spectroscopic techniques, is reported as a function of repetition rate and shot number within a burst. How the plasma parameters vary with diode operating conditions, such as gas puff pressure or insulating field strength, are also presented. In addition, these plasma parameters are compared with the parameters of the extracted beam

  5. All fiber based supercontinuum light source utilized for IR microscopy

    DEFF Research Database (Denmark)

    Dupont, Sune; Petersen, Christian; Thøgersen, Jan;

    2012-01-01

    An all fiber based supercontinuum light source is demonstrated for infrared microscopy. The high brightness and spatial coherence of the source facilitate fast high resolution measurements.......An all fiber based supercontinuum light source is demonstrated for infrared microscopy. The high brightness and spatial coherence of the source facilitate fast high resolution measurements....

  6. Improvement of medical education using web-based lecture repetition and extension: e-learning experiences of the Department of Obstetrics and Gynecology, University of Tuebingen

    Directory of Open Access Journals (Sweden)

    Wallwiener, Markus

    2006-11-01

    Full Text Available In order to improve the education of its medical students, the Department of Obstetrics and Gynecology of the University of Tuebingen established e-learning in terms of web-based lecture repetition and extension. Subsequent to lectures, questions are provided online. The participation is voluntary, but requires registration. The results of the analysed period (winter term 2004/2005, summer term 2005 and winter term 2005/2006 including more than 380 e-learning users are encouraging. An average of 45% of the target group used the offered online questions. The students who completed at least 75% of all prepared question units achieved significantly better results than their traditional learning fellow students (p=0.002. Users got more frequent the marks "good" and "very good". Twice as much conventional learning students as e-learning users failed the examination. E-Learning and the technical implementation are repeatedly appreciated by the students. In the future, more medical courses will be supplemented with e-learning, according to the students request.

  7. DNA fingerprinting of Lactobacillus crispatus strain CTV-05 by repetitive element sequence-based PCR analysis in a pilot study of vaginal colonization.

    Science.gov (United States)

    Antonio, May A D; Hillier, Sharon L

    2003-05-01

    Lactobacillus crispatus is one of the predominant hydrogen peroxide (H(2)O(2))-producing species found in the vagina and is under development as a probiotic for the treatment of bacterial vaginosis. In this study, we assessed whether DNA fingerprinting by repetitive element sequence-based PCR (rep-PCR) can be used to distinguish the capsule strain of L. crispatus (CTV-05) from other endogenous strains as well as other species of vaginal lactobacilli. Vaginal and rectal lactobacilli were identified to the species level by using whole-chromosome probe DNA hybridization. The DNAs from L. crispatus, L. jensenii, L. gasseri, and an as-yet-unnamed H(2)O(2)-negative Lactobacillus species designated 1086V were subjected to rep-PCR. The results of gel electrophoresis and ethidium bromide staining of the DNA fingerprints obtained were compared. L. crispatus CTV-05 had a unique DNA fingerprint compared to all other lactobacilli. DNA fingerprints for 27 production lots of L. crispatus sampled from 1994 through 2001 were identical to that of the original strain isolated in 1993, suggesting strain stability. In a pilot study of nine women, this DNA fingerprinting method distinguished CTV-05 from other endogenous vaginal lactobacilli prior to and after vaginal capsule use. rep-PCR DNA fingerprinting is useful for strain typing and for evaluating longitudinal loss or acquisition of vaginal lactobacilli used as probiotics. PMID:12734221

  8. Mitigation of nonlinearities using conjugate data repetition.

    Science.gov (United States)

    Eliasson, Henrik; Johannisson, Pontus; Karlsson, Magnus; Andrekson, Peter A

    2015-02-01

    We investigate a time-domain implementation of generalized phase-conjugated twin waves which we call conjugate data repetition. A theory based on time-domain perturbation analysis explaining the mitigation of nonlinear effects is provided, and the concept is evaluated using numerical simulations. Compared to PM-QPSK at the same channel bit rate, the single-channel transmission reach in a conventional system with standard single-mode fiber of conjugate data repetition-QPSK is increased by approximately a factor of 2. PMID:25836107

  9. 948 kHz repetition rate, picosecond pulse duration, all-PM 1.03 μm mode-locked fiber laser based on nonlinear polarization evolution

    Science.gov (United States)

    Boivinet, S.; Lecourt, J.-B.; Hernandez, Y.; Fotiadi, A.; Mégret, P.

    2014-05-01

    We present in this study a PM all-fiber laser oscillator passively mode-locked (ML) at 1.03 μm. The laser is based on Nonlinear Polarization Evolution (NPE) in polarization maintaining (PM) fibers. In order to obtain the mode-locking regime, a nonlinear reflective mirror including a fibered polarizer, a long fiber span and a fibered Faraday mirror (FM) is inserted in a Fabry-Perot laser cavity. In this work we explain the principles of operation of this original laser design that permits to generate ultrashort pulses at low repetition (lower that 1MHz) rate with a cavity length of 100 m of fiber. In this experiment, the measured pulse duration is about 6 ps. To our knowledge this is the first all-PM mode-locked laser based on the NPE with a cavity of 100m length fiber and a delivered pulse duration of few picosecondes. Furthermore, the different mode-locked regimes of the laser, i.e. multi-pulse, noise-like mode-locked and single pulse, are presented together with the ways of controlling the apparition of these regimes. When the single pulse mode-locking regime is achieved, the laser delivers linearly polarized pulses in a very stable way. Finally, this study includes numerical results which are obtained with the resolution of the NonLinear Schrodinger Equations (NLSE) with the Split-Step Fourier (SSF) algorithm. This modeling has led to the understanding of the different modes of operation of the laser. In particular, the influence of the peak power on the reflection of the nonlinear mirror and its operation are studied.

  10. A Web Based Puzzle for Energy Sources

    Directory of Open Access Journals (Sweden)

    Nilgun SECKEN

    2006-07-01

    Full Text Available At present many countries in the world consume too much fossil fuels such as petroleum, natural gas and coal to meet their energy needs. These fossil fuels are not renewable; their sources are limited and reducing gradually. More importantly they have been becoming more expensive day by day and their damage to the environment has been increasing. In spite of it, renewable energy sources are renewed and never run out. In addition there are many benefits of renewable energy. In this study a puzzle is prepared for primary-school students aiming at teaching of energy sources as a supplementary source. In the mean time, the puzzle we prepared reveals the advantages and disadvantages of renewable and fossil energy sources. Here, the student’s aim is to complete the puzzle by answering the questions respectively. .

  11. Repetition or Reconfiguration

    DEFF Research Database (Denmark)

    Vaarst Andersen, Kristina

    Experience, measured as seniority, is seldom sufficient to explain individual professionals’ abilities to contribute with valuable knowledge to team production. We need to pay attention to professionals’ knowledge and its fit to the project they engage in. In many industries and settings, the cog......Experience, measured as seniority, is seldom sufficient to explain individual professionals’ abilities to contribute with valuable knowledge to team production. We need to pay attention to professionals’ knowledge and its fit to the project they engage in. In many industries and settings......, the cognitive quality of knowledge held by individual professionals is the key microfoundation for project level performance. This paper empirically tests effects of project participants with and without knowledge diversity for project level performance for projects aiming for varying degrees of repetition...... and reconfiguration. The results indicate that project performance benefits form contributions from individuals holding diverse knowledge only when projects aim for high differentiation levels. This positive association is not just moderated, it may even be reversed in the case of professionals participating in low...

  12. Web-Based Music Study: The Effects of Listening Repetition, Song Likeability, and Song Understandability on EFL Learning Perceptions and Outcomes

    Science.gov (United States)

    Beasley, Robert E.; Chuang, Yuangshan

    2008-01-01

    This study adds to the body of empirical knowledge regarding the use of music in the EFL classroom. This original investigation centered around the following question: Does listening repetition, song likeability, and/or song understandability influence learning environment perceptions, learning perceptions, and/or learning outcomes in Taiwanese…

  13. 1% rms amplitude noise from a 30 fs continuum based source tunable from 800 to 1250 nm.

    Science.gov (United States)

    Resan, Bojan; Kurmulis, Sarah; Markovic, Vesna; Weingarten, Kurt J

    2016-06-27

    We present amplitude noise characterization of a low-cost continuum source tunable from 800 to 1250 nm, with the pulse duration of 30 fs, and average output power up to 140 mW at 80 MHz pulse repetition rate. The system is based on a SESAM-modelocked, solid-state Yb tungstate laser plus spectral broadening via a microstructured fiber followed by pulse compression with a simple prism compressor. The measured RMS amplitude noise of 1.2 to 2.5% in the whole tunable range is comparable to the modelocked oscillators. Additionally, we show an excellent agreement between simulated and the experimentally measured spectra. PMID:27410646

  14. Megawatt peak power, 1 kHz, 266 nm sub nanosecond laser source based on single-crystal fiber amplifier

    Science.gov (United States)

    Deyra, Loïc; Martial, Igor; Balembois, François; Diderjean, Julien; Georges, Patrick

    2013-06-01

    We report the realization of a UV source based on the fourth harmonic generation with LBO/BBO of a Nd:YAG passively Q-switched oscillator amplified in a single-crystal fiber. With careful optimization of the nonlinear components and parameters, we obtain 530 mW average power at 266 nm with pulses of 540 ps at the repetition rate of 1 kHz, which represents a 22.7 % total conversion efficiency from IR to UV and nearly 1 MW peak power. The beam quality M 2 is measured to be below 2.

  15. Megawatt peak power, 1 kHz, 266 nm sub nanosecond laser source based on single-crystal fiber amplifier

    OpenAIRE

    Deyra, Loïc; Martial, Igor; Julien, Didierjean; Balembois, François; Georges, Patrick

    2013-01-01

    International audience We report the realization of a UV source based on the fourth harmonic generation with LBO/BBO of a Nd:YAG passively Q:switched oscillator amplified in a single-crystal fiber. With careful optimization of the nonlinear components and parameters, we obtain 530 mW average power at 266 nm with pulses of 540 ps at the repetition rate of 1 kHz, which represents a 22.7% total conversion efficiency from IR to UV and nearly 1 MW peak power. The beam quality M² is measured to ...

  16. Neural Basis of Repetition Priming during Mathematical Cognition: Repetition Suppression or Repetition Enhancement?

    Science.gov (United States)

    Salimpoor, Valorie N.; Chang, Catie; Menon, Vinod

    2010-01-01

    We investigated the neural basis of repetition priming (RP) during mathematical cognition. Previous studies of RP have focused on repetition suppression as the basis of behavioral facilitation, primarily using word and object identification and classification tasks. More recently, researchers have suggested associative stimulus-response learning…

  17. Neutron Sources for Standard-Based Testing

    Energy Technology Data Exchange (ETDEWEB)

    Radev, Radoslav [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McLean, Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-11-10

    The DHS TC Standards and the consensus ANSI Standards use 252Cf as the neutron source for performance testing because its energy spectrum is similar to the 235U and 239Pu fission sources used in nuclear weapons. An emission rate of 20,000 ± 20% neutrons per second is used for testing of the radiological requirements both in the ANSI standards and the TCS. Determination of the accurate neutron emission rate of the test source is important for maintaining consistency and agreement between testing results obtained at different testing facilities. Several characteristics in the manufacture and the decay of the source need to be understood and accounted for in order to make an accurate measurement of the performance of the neutron detection instrument. Additionally, neutron response characteristics of the particular instrument need to be known and taken into account as well as neutron scattering in the testing environment.

  18. Simple Signal Source based Micro Controller

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Using micro controller, DAC and Multi-periods syn-thesis, we can buildup a very simple signal source with precisefrequency, amplitude and waveform. Wave parameters can beprogrammed in advance. The circuit can satisfy some special re-quirements.

  19. Particle Swarm Optimization Based Source Seeking

    OpenAIRE

    Zou, Rui; Kalivarapu, Vijay; Winer, Eliot; Oliver, James; Bhattacharya, Sourabh

    2015-01-01

    Signal source seeking using autonomous vehicles is a complex problem. The complexity increases manifold when signal intensities captured by physical sensors onboard are noisy and unreliable. Added to the fact that signal strength decays with distance, noisy environments make it extremely difficult to describe and model a decay function. This paper addresses our work with seeking maximum signal strength in a continuous electromagnetic signal source with mobile robots, using Particle Swarm Opti...

  20. BOOTSTRAP-BASED STATISTICAL THRESHOLDING FOR MEG SOURCE RECONSTRUCTION IMAGES

    OpenAIRE

    Sekihara, Kensuke; Sahani, Maneesh; Nagarajan, Srikantan S.

    2004-01-01

    This paper proposes a bootstrap-based statistical method for extracting target source activities from MEG/EEG source reconstruction results. The method requires measurements in a control condition, which contains only non-target source activities. The method derives, at each pixel location, an empirical probability distribution of the non-target source activity using bootstrapped reconstruction obtained from the control period. The statistical threshold that can extract the target source acti...

  1. A new algorithm for EEG source reconstruction based on LORETA by contracting the source region

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new method is presented for EEG source reconstruction based on multichannel surface EEG recordings. From the low-resolution tomography obtained by the low resolution electromagnetic tomography algorithm (LORETA), this method acquires the source tomography, which has high-resolution by contracting the source region. In contrast to focal underdetermined system solver (FOCUSS), this method can gain more accurate result under certain circumstances.

  2. TRIPPy: Python-based Trailed Source Photometry

    Science.gov (United States)

    Fraser, Wesley C.; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michael E.; Pike, Rosemary E.; Kavelaars, JJ; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-05-01

    TRIPPy (TRailed Image Photometry in Python) uses a pill-shaped aperture, a rectangle described by three parameters (trail length, angle, and radius) to improve photometry of moving sources over that done with circular apertures. It can generate accurate model and trailed point-spread functions from stationary background sources in sidereally tracked images. Appropriate aperture correction provides accurate, unbiased flux measurement. TRIPPy requires numpy, scipy, matplotlib, Astropy (ascl:1304.002), and stsci.numdisplay; emcee (ascl:1303.002) and SExtractor (ascl:1010.064) are optional.

  3. A Web Based Puzzle for Energy Sources

    OpenAIRE

    Nilgun SECKEN

    2006-01-01

    At present many countries in the world consume too much fossil fuels such as petroleum, natural gas and coal to meet their energy needs. These fossil fuels are not renewable; their sources are limited and reducing gradually. More importantly they have been becoming more expensive day by day and their damage to the environment has been increasing. In spite of it, renewable energy sources are renewed and never run out. In addition there are many benefits of renewable energy. In this study a puz...

  4. Repetitive frequency electromagnetic pulse simulator based on inductive adding technique%基于感应叠加技术的重复频率电磁脉冲模拟器

    Institute of Scientific and Technical Information of China (English)

    于成大; 徐笑娟; 罗进; 何山红; 冯德仁

    2012-01-01

    The development and experiment of a small bounded wave simulator are introduced, including the development of the double exponential repetitive frequency pulse source based on the hydrogen thyratron inductive-adder, the design of output coaxial shielding structure, the calculation of the field distribution of the output transformer, the development of the small flat-plate radiator, and the calculation and simulation about the working space E-field of the radiator. The preliminary measurement results of the working space E-field of the radiator are also presented. The experiment results show that the E-field in the working space of the radiator space accords with the linear superposition principle, even if there are differences between the parameters of thyratrons and between the parameters of grid trigger clocks.%介绍了小型平板型有界波模拟器的研制和实验,包括基于氢闸流管感应叠加技术的双指数波重频脉冲源的研制、输出同轴屏蔽结构的设计与输出变压器磁场分布的计算、小型平板型辐射器的设计及工作区内电场的计算与仿真,给出了辐射器工作区内电场初步测量的结果.实验结果表明:即使在感应叠加单元的氢闸流管器件和栅极触发时钟的参数存在差异的情况下,辐射器的工作区内电场基本上符合线性叠加原则.

  5. High-power, high-repetition-rate performance characteristics of β-BaB2O4 for single-pass picosecond ultraviolet generation at 266 nm

    OpenAIRE

    Kumar, S. Chaitanya; Canals Casals, J.; Wei, Junxiong; Ebrahim-Zadeh, Majid

    2015-01-01

    We report a systematic study on the performance characteristics of a high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 266 nm based on β-BaB2O4 (BBO). The source, based on single-pass fourth harmonic generation (FHG) of a compact Yb-fiber laser in a two-crystal spatial walk-off compensation scheme, generates up to 2.9 W of average power at 266 nm at a pulse repetition rate of ~80 MHz with a single-pass FHG efficiency of 35% from the green to UV. Detrimental issues such a...

  6. Note: All solid-state high repetitive sub-nanosecond risetime pulse generator based on bulk gallium arsenide avalanche semiconductor switches

    Science.gov (United States)

    Hu, Long; Su, Jiancang; Ding, Zhenjie; Hao, Qingsong; Fan, Yajun; Liu, Chunliang

    2016-08-01

    An all solid-state high repetitive sub-nanosecond risetime pulse generator featuring low-energy-triggered bulk gallium arsenide (GaAs) avalanche semiconductor switches and a step-type transmission line is presented. The step-type transmission line with two stages is charged to a potential of 5.0 kV also biasing at the switches. The bulk GaAs avalanche semiconductor switch closes within sub-nanosecond range when illuminated with approximately 87 nJ of laser energy at 905 nm in a single pulse. An asymmetric dipolar pulse with peak-to-peak amplitude of 9.6 kV and risetime of 0.65 ns is produced on a resistive load of 50 Ω. A technique that allows for repetition-rate multiplication of pulse trains experimentally demonstrated that the parallel-connected bulk GaAs avalanche semiconductor switches are triggered in sequence. The highest repetition rate is decided by recovery time of the bulk GaAs avalanche semiconductor switch, and the operating result of 100 kHz of the generator is discussed.

  7. The Research of UPS Inverter Based on PID and Repetitive Control%基于PID和重复控制的UPS逆变器的研究

    Institute of Scientific and Technical Information of China (English)

    张震; 柴文野; 潘登; 任冲

    2011-01-01

    A control strategy combining repetitive control with PID control for UPS output voltage is proposed according to the free static -error tracking characteristic belonging to repetitive control and fast response characteristic belonging to PID control. The repetitive control reduces the distortion which the periodic disturbance produces and enhances steady state performance; the PID control reduces overshooting number and oscillation when the system receives the big perturbation and improves dynamic performance of system. The results show that the compound control makes the system achieve good dynamic and static performance and improve output voltage quality of inverter.%根据重复控制的无静态误差跟踪性和PID控制的快速响应特性,提出了UPS逆变器输出电压的重复与PID复合控制策略.重复控制可以减小周期性扰动产生的畸变,提高了系统的稳态性能;PID控制可以减小当系统受到较大的扰动时出现的超调和振荡,改善了系统的动态性能.实验结果表明,这种复合控制使系统得到了良好的动态和稳态特性,提高了逆变器的输出电压质量.

  8. Multicolor multiphoton microscopy based on a nanosecond supercontinuum laser source.

    Science.gov (United States)

    Lefort, Claire; O'Connor, Rodney P; Blanquet, Véronique; Magnol, Laetitia; Kano, Hideaki; Tombelaine, Vincent; Lévêque, Philippe; Couderc, Vincent; Leproux, Philippe

    2016-07-01

    Multicolor multiphoton microscopy is experimentally demonstrated for the first time on a spectral bandwidth of excitation of 300 nm (full width half maximum) thanks to the implementation a nanosecond supercontinuum (SC) source compact and simple with a low repetition rate. The interest of such a wide spectral bandwidth, never demonstrated until now, is highlighted in vivo: images of glioma tumor cells stably expressing eGFP grafted on the brain of a mouse and its blood vessels network labelled with Texas Red(®) are obtained. These two fluorophores have a spectral bandwidth covering the whole 300 nm available. In parallel, a similar image quality is obtained on a sample of mouse muscle in vitro when excited with this nanosecond SC source or with a classical high rate, femtosecond and quasi monochromatic laser. This opens the way for (i) a simple and very complete biological characterization never performed to date with multiphoton processes, (ii) multiple means of contrast in nonlinear imaging allowed by the use of numerous fluorophores and (iii) other multiphoton processes like three-photon ones. PMID:26872004

  9. Fuzzy Adaptive Repetitive Control for Periodic Disturbance with Its Application to High Performance Permanent Magnet Synchronous Motor Speed Servo Systems

    Directory of Open Access Journals (Sweden)

    Junxiao Wang

    2016-09-01

    Full Text Available For reducing the steady state speed ripple, especially in high performance speed servo system applications, the steady state precision is more and more important for real servo systems. This paper investigates the steady state speed ripple periodic disturbance problem for a permanent magnet synchronous motor (PMSM servo system; a fuzzy adaptive repetitive controller is designed in the speed loop based on repetitive control and fuzzy information theory for reducing periodic disturbance. Firstly, the various sources of the PMSM speed ripple problem are described and analyzed. Then, the mathematical model of PMSM is given. Subsequently, a fuzzy adaptive repetitive controller based on repetitive control and fuzzy logic control is designed for the PMSM speed servo system. In addition, the system stability analysis is also deduced. Finally, the simulation and experiment implementation are respectively based on the MATLAB/Simulink and TMS320F2808 of Texas instrument company, DSP (digital signal processor hardware platform. Comparing to the proportional integral (PI controller, simulation and experimental results show that the proposed fuzzy adaptive repetitive controller has better periodic disturbance rejection ability and higher steady state precision.

  10. sources

    Directory of Open Access Journals (Sweden)

    Shu-Yin Chiang

    2002-01-01

    Full Text Available In this paper, we study the simplified models of the ATM (Asynchronous Transfer Mode multiplexer network with Bernoulli random traffic sources. Based on the model, the performance measures are analyzed by the different output service schemes.

  11. An Open-Source Based ITS Platform

    DEFF Research Database (Denmark)

    Andersen, Ove; Krogh, Benjamin Bjerre; Torp, Kristian

    2013-01-01

    In this paper, a complete platform used to compute travel times from GPS data is described. Two approaches to computing travel time are proposed one based on points and one based on trips. Overall both approaches give reasonable results compared to existing manual estimated travel times. However,...

  12. 2 μm and mid-IR fiber-laser-based sources for OCM

    Science.gov (United States)

    Kieleck, C.; Berrou, A.; Kneis, C.; Donelan, B.; Eichhorn, M.

    2014-10-01

    This paper describes new laser sources and non linear conversion setups for 2 μm and mid-IR generation based on fiber technologies developed at ISL. Especially for jamming heat-seeking missiles, these novel designs allow to propose future compact, efficient and integrable laser systems. The specialty of the ISL technology lies in the use of single 2 μm fiber laser oscillators, which deliver the full output peak power to pump optical parametric oscillators or nonlinear fibers. No multi-stage amplifiers at 2 μm or 1.55 μm are necessary to efficiently pump non linear converters to obtained useful energies in the mid-infrared spectral range. This technology leads to efficient, simple and promising setups to be implemented in flying platforms. The best results achieved in continuous-wave (CW), Q-switched (QS) and mode-locked (ML) regimes with fiber lasers based on Tm3+-doped and Tm3+,Ho3+-codoped fibers are presented. Up to 70 W of average power was achieved around 2 μm with a Tm3+-doped fiber in CW regime. In ML regimes, at a repetition rate of 66 MHz, 50 W of average power was reached. In QS regime, up to 32 W of average power was generated around 2 μm with a polarization maintaining Tm3+-doped fiber at a repetition rate of 40 kHz. With a Tm3+,Ho3+-codoped fiber, up to 25 W of average power was obtained around 2070 nm in Q-switched regime. For example at 50 kHz, the pulse duration was around 50 ns at the maximum output power. The M2 was estimated to be less than 1.2. The emission from QS fiber lasers was used to directly pump OP-GaAs and ZGP OPOs. For example, in band II, up to 6.5 W of averaged power was recently obtained from a ZGP OPO pumped by a Tm3+-doped fiber laser. At 40 kHz repetition rate, the pulse duration was around 65 ns at the maximum output power. For 3 W of averaged output power, the M2 of the signal beam was estimated to be less than 2.1 and less than 2.4 for the idler beam. Using a mode-locked Tm3+-doped fiber laser to pump a ZBLAN fiber at an

  13. Neutron source based on the TORNADO trap

    International Nuclear Information System (INIS)

    The TORNADO magnetic trap as a source of thermonuclear neutrons with 108 neutron per a pulse in the D-D reaction is considered. The construction of magnetic traps both with stationary and quasistationary modes of their operation is shown to be possible. The results of numerical calculation of the magnetic system parameters are given, analysis of permissible mechanical loads, turns displacements of and magnetic fields in the trap is carried out. Considerable decrease of pondermotive forces affecting the turns of an internal spiral when conserving thermo-insulating properties of the magnetic trap field is shown to be possible. The loads of the trap spiral magnet coils are shown to be also acceptable to form the stationary magnetic field of the 2 Tl order in the magnetic barrier

  14. Van de Graaff based positron source production

    Science.gov (United States)

    Lund, Kasey Roy

    The anti-matter counterpart to the electron, the positron, can be used for a myriad of different scientific research projects to include materials research, energy storage, and deep space flight propulsion. Currently there is a demand for large numbers of positrons to aid in these mentioned research projects. There are different methods of producing and harvesting positrons but all require radioactive sources or large facilities. Positron beams produced by relatively small accelerators are attractive because they are easily shut down, and small accelerators are readily available. A 4MV Van de Graaff accelerator was used to induce the nuclear reaction 12C(d,n)13N in order to produce an intense beam of positrons. 13N is an isotope of nitrogen that decays with a 10 minute half life into 13C, a positron, and an electron neutrino. This radioactive gas is frozen onto a cryogenic freezer where it is then channeled to form an antimatter beam. The beam is then guided using axial magnetic fields into a superconducting magnet with a field strength up to 7 Tesla where it will be stored in a newly designed Micro-Penning-Malmberg trap. Several source geometries have been experimented on and found that a maximum antimatter beam with a positron flux of greater than 0.55x10 6 e+s-1 was achieved. This beam was produced using a solid rare gas moderator composed of krypton. Due to geometric restrictions on this set up, only 0.1-1.0% of the antimatter was being frozen to the desired locations. Simulations and preliminary experiments suggest that a new geometry, currently under testing, will produce a beam of 107 e+s-1 or more.

  15. Advanced high-power optical parametric oscillators synchronously pumped by ultrafast fibre-based sources

    OpenAIRE

    Kienle, Florian

    2012-01-01

    This thesis is concerned with investigating the generation of ultra short, tunable pulses at high average power and / or high pulse energy using synchronously pumped optical parametric oscillators (OPO) and appropriate power-scalable fibre-amplifier pump sources. Two types of pump sources with average powers up to ? 100W are considered: (1) a picosecond, all-fiberised, high-power, variable-repetition-rate, Yb:fibre-amplified, gain-switched laser diode system and (2) a femtosecond, high-power,...

  16. Hiding the Source Based on Limited Flooding for Sensor Networks

    Directory of Open Access Journals (Sweden)

    Juan Chen

    2015-11-01

    Full Text Available Wireless sensor networks are widely used to monitor valuable objects such as rare animals or armies. Once an object is detected, the source, i.e., the sensor nearest to the object, generates and periodically sends a packet about the object to the base station. Since attackers can capture the object by localizing the source, many protocols have been proposed to protect source location. Instead of transmitting the packet to the base station directly, typical source location protection protocols first transmit packets randomly for a few hops to a phantom location, and then forward the packets to the base station. The problem with these protocols is that the generated phantom locations are usually not only near the true source but also close to each other. As a result, attackers can easily trace a route back to the source from the phantom locations. To address the above problem, we propose a new protocol for source location protection based on limited flooding, named SLP. Compared with existing protocols, SLP can generate phantom locations that are not only far away from the source, but also widely distributed. It improves source location security significantly with low communication cost. We further propose a protocol, namely SLP-E, to protect source location against more powerful attackers with wider fields of vision. The performance of our SLP and SLP-E are validated by both theoretical analysis and simulation results.

  17. Repetition in English Political Public Speaking

    Institute of Scientific and Technical Information of China (English)

    李红梅

    2010-01-01

    Repetition is frequently used in English political public speaking to make it easy to be remembered and powerful to move the feelings of the public. This paper is intended to analyze the functions of repetition and different levels of repetition to highlight the significance of repetition in English political public speaking and the ability of using it in practice.

  18. Computer-Related Repetitive Stress Injuries

    Science.gov (United States)

    ... Growth Computer-Related Repetitive Stress Injuries KidsHealth > For Parents > Computer-Related Repetitive Stress Injuries Print A A A Text Size What's ... hours at the computer. So it's important for parents to know about the causes of repetitive stress injuries and how to prevent them. About Repetitive ...

  19. Sourcing Team Behavior in Project-Based MNE's

    DEFF Research Database (Denmark)

    Hansen, Anders Peder Lysholm

    2014-01-01

    This paper presents and discusses a multiple case study of three cross-functional category teams responsible for sourcing critical components within multi-national, project-based enterprises. The study focused on behaviour and management of the sourcing teams and found that the sourcing process...... across the three cases was characterized by conflict between departments represented in the category teams. This resulted in unfortunate sourcing team behaviour and unaligned performance management, which in turn had a number of adverse effects. Further research on how to create a holistic and balanced...... team perspective in the sourcing teams is suggested....

  20. Generating diffuse discharge via repetitive nanosecond pulses and line-line electrodes in atmospheric air

    Science.gov (United States)

    Li, Lee; Liu, Yun-Long; Ge, Ya-Feng; Bin, Yu; Huang, Jia-Jia; Lin, Fo-Chan

    2013-10-01

    Diffuse discharge in atmospheric air can generate extremely high power density and large-scale non-thermal plasma. An achievable method of generating diffuse discharge is reported in this paper. Based on the resonance theory, a compact high-voltage repetitive nanosecond pulse generator (HRNPG) has been developed as discharge excitation source. The HRNPG mainly consists of repetitive charging circuit, Tesla transformer and sharpening switch. With the voltage lower than 1.0 kV, the primary repetitive charging circuit comprises two fast thyristors as low-voltage switches. A spiral Tesla transformer is designed to provide a peak transformation ratio of more than 100. The HRNPG prototype is capable of generating a pulse with over 100 kV peak voltage and ˜30 ns rise-time at the repetition frequency of 500 Hz. Using the copper line electrodes with a diameter of 0.4 mm, the gaps with highly non-uniform electric field are structured. With the suitable gap spacing and applied pulse, the glow-like diffuse discharge has been generated in line-type and ring-type electrode pairs. Some typical images are presented.

  1. Simple quantitative PCR approach to reveal naturally occurring and mutation-induced repetitive sequence variation on the Drosophila Y chromosome.

    Directory of Open Access Journals (Sweden)

    John C Aldrich

    Full Text Available Heterochromatin is a significant component of the human genome and the genomes of most model organisms. Although heterochromatin is thought to be largely non-coding, it is clear that it plays an important role in chromosome structure and gene regulation. Despite a growing awareness of its functional significance, the repetitive sequences underlying some heterochromatin remain relatively uncharacterized. We have developed a real-time quantitative PCR-based method for quantifying simple repetitive satellite sequences and have used this technique to characterize the heterochromatic Y chromosome of Drosophila melanogaster. In this report, we validate the approach, identify previously unknown satellite sequence copy number polymorphisms in Y chromosomes from different geographic sources, and show that a defect in heterochromatin formation can induce similar copy number polymorphisms in a laboratory strain. These findings provide a simple method to investigate the dynamic nature of repetitive sequences and characterize conditions which might give rise to long-lasting alterations in DNA sequence.

  2. Modeling repetitive motions using structured light.

    Science.gov (United States)

    Xu, Yi; Aliaga, Daniel G

    2010-01-01

    Obtaining models of dynamic 3D objects is an important part of content generation for computer graphics. Numerous methods have been extended from static scenarios to model dynamic scenes. If the states or poses of the dynamic object repeat often during a sequence (but not necessarily periodically), we call such a repetitive motion. There are many objects, such as toys, machines, and humans, undergoing repetitive motions. Our key observation is that when a motion-state repeats, we can sample the scene under the same motion state again but using a different set of parameters; thus, providing more information of each motion state. This enables robustly acquiring dense 3D information difficult for objects with repetitive motions using only simple hardware. After the motion sequence, we group temporally disjoint observations of the same motion state together and produce a smooth space-time reconstruction of the scene. Effectively, the dynamic scene modeling problem is converted to a series of static scene reconstructions, which are easier to tackle. The varying sampling parameters can be, for example, structured-light patterns, illumination directions, and viewpoints resulting in different modeling techniques. Based on this observation, we present an image-based motion-state framework and demonstrate our paradigm using either a synchronized or an unsynchronized structured-light acquisition method.

  3. Light pollution simulations for planar ground-based light sources.

    Science.gov (United States)

    Kocifaj, Miroslav

    2008-02-20

    The light pollution model is employed to analyze spatial behavior of luminance at the night sky under cloudless and overcast conditions. Enhanced light excess is particularly identified at cloudy skies, because the clouds efficiently contribute to the downward luminous flux. It is evident that size of ground-based light sources can play an important role in the case of overcast sky conditions. Nevertheless, the realistically sized light sources are rarely embedded into light pollution modeling, and rather they are replaced by simple point sources. We discuss the discrepancies between sky luminance distributions when at first the planar light sources are considered and at second the point-source approximation is accepted. The found differences are noticeable if the size of the light source, distance to the observer, and altitude of a cloudy layer are comparable one to the other. Compared with point-source approximation, an inclusion of the size factor into modeling the light sources leads to partial elimination of the steep changes of sky luminance (typical for point sources of light). The narrow and sharp light pillars normally presented on the sky illuminated by point light sources can disappear or fuse together when two or more nearby light sources are considered with their real sizes. Sky elements situated close to the horizon will glow efficiently if luminous flux originates from two-dimensional ground-based entities (such as cities or villages). PMID:18288228

  4. Varianish: Jamming with Pattern Repetition

    Directory of Open Access Journals (Sweden)

    Jort Band

    2014-10-01

    Full Text Available In music, patterns and pattern repetition are often regarded as a machine-like task, indeed often delegated to drum Machines and sequencers. Nevertheless, human players add subtle differences and variations to repeated patterns that are musically interesting and often unique. Especially when looking at minimal music, pattern repetitions create hypnotic effects and the human mind blends out the actual pattern to focus on variation and tiny differences over time. Varianish is a musical instrument that aims at turning this phenomenon into a new musical experience for musician and audience: Musical pattern repetitions are found in live music and Varianish generates additional (musical output accordingly that adds substantially to the overall musical expression. Apart from the theory behind the pattern finding and matching and the conceptual design, a demonstrator implementation of Varianish is presented and evaluated.

  5. SOURCE EXPLORER: Towards Web Browser Based Tools for Astronomical Source Visualization and Analysis

    Science.gov (United States)

    Young, M. D.; Hayashi, S.; Gopu, A.

    2014-05-01

    As a new generation of large format, high-resolution imagers come online (ODI, DECAM, LSST, etc.) we are faced with the daunting prospect of astronomical images containing upwards of hundreds of thousands of identifiable sources. Visualizing and interacting with such large datasets using traditional astronomical tools appears to be unfeasible, and a new approach is required. We present here a method for the display and analysis of arbitrarily large source datasets using dynamically scaling levels of detail, enabling scientists to rapidly move from large-scale spatial overviews down to the level of individual sources and everything in-between. Based on the recognized standards of HTML5+JavaScript, we enable observers and archival users to interact with their images and sources from any modern computer without having to install specialized software. We demonstrate the ability to produce large-scale source lists from the images themselves, as well as overlaying data from publicly available source ( 2MASS, GALEX, SDSS, etc.) or user provided source lists. A high-availability cluster of computational nodes allows us to produce these source maps on demand and customized based on user input. User-generated source lists and maps are persistent across sessions and are available for further plotting, analysis, refinement, and culling.

  6. Multiterminal Source Coding with an Entropy-Based Distortion Measure

    OpenAIRE

    Courtade, Thomas; Wesel, Richard

    2011-01-01

    In this paper, we consider a class of multiterminal source coding problems, each subject to distortion constraints computed using a specific, entropy-based, distortion measure. We provide the achievable rate distortion region for two cases and, in so doing, we demonstrate a relationship between the lossy multiterminal source coding problems with our specific distortion measure and (1) the canonical Slepian-Wolf lossless distributed source coding network, and (2) the Ahlswede-K\\"{o}rner-Wyner ...

  7. Patch nearfield acoustic holography based on the equivalent source method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    On the basis of nearfield acoustic holography (NAH) based on the equivalent source method (ESM), patch NAH based on the ESM is proposed. The method overcomes the shortcoming in the conventional NAH that the hologram surface should be larger than the source surface. It need not to discretize the whole source and its measurement need not to cover the whole source. The measurement may be performed over the region of interest, and the reconstruction can be done in the region directly. The method is flexible in applications, stable in computation, and very easy to implement. It has good potential applications in engineering. The nu- merical simulations show the invalidity of the conventional NAH based on the ESM and prove the validities of the proposed method for reconstructing a partial source and the regularization for reducing the error effect of the pressure measured on the hologram surface.

  8. Patch nearfield acoustic holography based on the equivalent source method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    On the basis of nearfield acoustic holography (NAH) based on the equivalent source method (ESM), patch NAH based on the ESM is proposed. The method overcomes the shortcoming in the conventional NAH that the hologram surface should be larger than the source surface. It need not to discretize the whole source and its measurement need not to cover the whole source. The measurement may be performed over the region of interest, and the reconstruction can be done in the region directly. The method is flexible in applications, stable in computation, and very easy to implement. It has good potential applications in engineering. The numerical simulations show the invalidity of the conventional NAH based on the ESM and prove the validities of the proposed method for reconstructing a partial source and the regularization for reducing the error effect of the pressure measured on the hologram surface.

  9. Source—to—Source Conversion Based on Formal Definition

    Institute of Scientific and Technical Information of China (English)

    张幸儿; 李建新; 等

    1991-01-01

    This paper proposes the idea of source-to-source conversion between two heterogeneous high-level programming languages.The conversion is based on formal definition and oriented to multi-pairs of languages.The issues in conversion from PASCAL to C are also discussed.

  10. Repetitive elements in parasitic protozoa

    OpenAIRE

    Clayton Christine

    2010-01-01

    Abstract A recent paper published in BMC Genomics suggests that retrotransposition may be active in the human gut parasite Entamoeba histolytica. This adds to our knowledge of the various types of repetitive elements in parasitic protists and the potential influence of such elements on pathogenicity. See research article http://www.biomedcentral.com/1471-2164/11/321

  11. Repetitive elements in parasitic protozoa

    Directory of Open Access Journals (Sweden)

    Clayton Christine

    2010-05-01

    Full Text Available Abstract A recent paper published in BMC Genomics suggests that retrotransposition may be active in the human gut parasite Entamoeba histolytica. This adds to our knowledge of the various types of repetitive elements in parasitic protists and the potential influence of such elements on pathogenicity. See research article http://www.biomedcentral.com/1471-2164/11/321

  12. AlInGaN-Based Superlattice Terahertz Source Project

    Data.gov (United States)

    National Aeronautics and Space Administration — WaveBand Corporation in collaboration with Virginia Commonwealth University proposes to design and fabricate a new sub-millimeter source based on an InAlGaN...

  13. Single channel blind source separation based on ICA feature extraction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new technique is proposed to solve the blind source separation (BSS) given only a single channel observation. The basis functions and the density of the coefficients of source signals learned by ICA are used as the prior knowledge. Based on the learned prior information the learning rules of single channel BSS are presented by maximizing the joint log likelihood of the mixed sources to obtain source signals from single observation,in which the posterior density of the given measurements is maximized. The experimental results exhibit a successful separation performance for mixtures of speech and music signals.

  14. Short-time X-ray diffraction with an efficient-optimized, high repetition-rate laser-plasma X-ray-source; Kurzzeit-Roentgenbeugung mit Hilfe einer Effizienz-optimierten, hochrepetierenden Laser-Plasma-Roentgenquelle

    Energy Technology Data Exchange (ETDEWEB)

    Kaehle, Stephan

    2009-04-23

    This thesis deals with the production and application of ultrashort X-ray pulses. In the beginning different possibilities for the production of X-ray pulses with pulse durations of below one picosecond are presented, whereby the main topic lies on the so called laser-plasma X-ray sources with high repetition rate. In this case ultrashort laser pulses are focused on a metal, so that in the focus intensities of above 10{sup 16} W/cm{sup 2} dominate. In the ideal case in such way ultrafast electrons are produced, which are responsible for line radiation. In these experiments titanium K{sub {alpha}} radiation is produced, thes photons possess an energy of 4.51 keV. For the efficient production of line radiation here the Ti:Sa laser is optimized in view of the laser energy and the pulse shape and the influence of the different parameters on the K{sub {alpha}} production systematically studied. The influences of laser intensity, system-conditioned pre-pulses and of phase modulation are checked. It turns out that beside the increasement of the K{sub {alpha}} radiation by a suited laser intensity a reduction of the X-ray background radiation is of deciding importance for the obtaining of clear diffraction images. This background radiation is mainly composed of bremsstrahlung. It can be suppressed by the avoidance of intrinsic pre-pulses and by means of 2nd-order phase modulation. By means of optical excitation and X-ray exploration experiments the production of acoustic waves after ultrashort optical excitation in a 150 nm thick Ge(111) film on Si(111) is studied. These acoustic waves are driven by thermal (in this time scale time-independent) and electronic (time dependent) pressure amounts. As essential results it turns out that the relative amount of the electronic pressure increases with decreasing excitation density. [German] Diese Arbeit befasst sich mit der Erzeugung und Anwendung ultrakurzer Roentgenimpulse. Zu Beginn werden verschiedene Moeglichkeiten zur

  15. Filter selection based on light source for multispectral imaging

    Science.gov (United States)

    Xu, Peng; Xu, Haisong

    2016-07-01

    In multispectral imaging, it is necessary to select a reduced number of filters to balance the imaging efficiency and spectral reflectance recovery accuracy. Due to the combined effect of filters and light source on reflectance recovery, the optimal filters are influenced by the employed light source in the multispectral imaging system. By casting the filter selection as an optimization issue, the selection of optimal filters corresponding to the employed light source proceeds with respect to a set of target samples utilizing one kind of genetic algorithms, regardless of the detailed spectral characteristics of the light source, filters, and sensor. Under three light sources with distinct spectral power distributions, the proposed filter selection method was evaluated on a filter-wheel based multispectral device with a set of interference filters. It was verified that the filters derived by the proposed method achieve better spectral and colorimetric accuracy of reflectance recovery than the conventional one under different light sources.

  16. An accelerator-based epithermal photoneutron source for BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Nigg, D.W.; Mitchell, H.E.; Harker, Y.D.; Yoon, W.Y. [and others

    1995-11-01

    Therapeutically-useful epithermal-neutron beams for BNCT are currently generated by nuclear reactors. Various accelerator-based neutron sources for BNCT have been proposed and some low intensity prototypes of such sources, generally featuring the use of proton beams and beryllium or lithium targets have been constructed. This paper describes an alternate approach to the realization of a clinically useful accelerator-based source of epithermal neutrons for BNCT that reconciles the often conflicting objectives of target cooling, neutron beam intensity, and neutron beam spectral purity via a two stage photoneutron production process.

  17. Single-pass high harmonic generation at high repetition rate and photon flux

    Science.gov (United States)

    Hädrich, Steffen; Rothhardt, Jan; Krebs, Manuel; Demmler, Stefan; Klenke, Arno; Tünnermann, Andreas; Limpert, Jens

    2016-09-01

    Sources of short wavelength radiation with femtosecond to attosecond pulse durations, such as synchrotrons or free electron lasers, have already made possible numerous, and will facilitate more, seminal studies aimed at understanding atomic and molecular processes on fundamental length and time scales. Table-top sources of coherent extreme ultraviolet to soft x-ray radiation enabled by high harmonic generation (HHG) of ultrashort pulse lasers have also gained significant attention in the last few years due to their enormous potential for addressing a plethora of applications, therefore constituting a complementary source to large-scale facilities (synchrotrons and free electron lasers). Ti:sapphire based laser systems have been the workhorses for HHG for decades, but are limited in repetition rate and average power. On the other hand, it has been widely recognized that fostering applications in fields such as photoelectron spectroscopy and microscopy, coincidence detection, coherent diffractive imaging and frequency metrology requires a high repetition rate and high photon flux HHG sources. In this article we will review recent developments in realizing the demanding requirement of producing a high photon flux and repetition rate at the same time. Particular emphasis will be put on suitable ultrashort pulse and high average power lasers, which directly drive harmonic generation without the need for external enhancement cavities. To this end we describe two complementary schemes that have been successfully employed for high power fiber lasers, i.e. optical parametric chirped pulse amplifiers and nonlinear pulse compression. Moreover, the issue of phase-matching in tight focusing geometries will be discussed and connected to recent experiments. We will highlight the latest results in fiber laser driven high harmonic generation that currently produce the highest photon flux of all existing sources. In addition, we demonstrate the first promising applications and

  18. Improvement of Polytetrafluoroethylene Surface Energy by Repetitive Pulse Non-Thermal Plasma Treatment in Atmospheric Air%Improvement of Polytetrafluoroethylene Surface Energy by Repetitive Pulse Non-Thermal Plasma Treatment in Atmospheric Air

    Institute of Scientific and Technical Information of China (English)

    杨国清; 张冠军; 张文元

    2011-01-01

    Improvement of polytetrafluoroethylene surface energy by non-thermal plasma treatment is presented, using a nanosecond-positive-edge repetitive pulsed dielectric barrier discharge generator in atmospheric air. The electrical parameters including discharging power, peak and density of micro-discharge current were calculated, and the electron energy was estimated. Surface treatment experiments of polytetrafluoroethylene films were conducted for both different applied voltages and different treating durations. Results show that the surface energy of polytetrafluoroethylene film could be improved to 40 mJ/m2 or more by plasma treatment. Surface roughness measurement and surface X-ray photoelectron spectroscopy analysis indicate that there are chemical etching and implantation of polar oxygen groups in the sample surface treating process, resulting in the improvement of the sample surface energy. Compared with an AC source of 50 Hz, the dielectric barrier discharges generated by a repetitive pulsed source could provide higher peak power, lower mean power, larger micro-discharge current density and higher electron energy. Therefore, with the same applied peak voltage and treating duration, the improvement of polytetrafluoroethylene surface energy using repetitive pulsed plasma is more effective, and the plasma treatment process based on repetitive pulsed dielectric barrier discharges in air is thus feasible and applicable.

  19. A COMPARATIVE STUDY BASED ON OPEN SOURCE CONTENT MANAGEMENT SYSTEMS

    Directory of Open Access Journals (Sweden)

    SUBHAM SARKAR

    2010-12-01

    Full Text Available Development of websites using traditional technologies involve large amount of coding and huge efforts in small tasks. Moreover, to storedata the designers need to use and maintain a database and connect the website through JDBC and ODBC for database transactions andverifications. Such development and management of websites is a difficult task and consumes large human resources and investments. Even for regular updation of websites, the professionals need to be hired. A content management system (CMS is a system used to manage the contents of a web site. It is a collection of (manual or computer-based procedures used to manage work flow in a collaborativeenvironment. The procedures are designed to allow for a large number of people to contribute to and share stored data; control access todata, based on user roles; aid in easy storage and retrieval of data; reduce repetitive duplicate input; improve the ease of report writing; and improve communication between users. In a CMS, data can be defined as nearly anything, i.e., documents, movies, pictures, phone numbers, scientific data, etc. The features of a CMS system vary but most include web-based publishing, format management, revision control, and indexing, search, and retrieval. A CMS can be easily embedded into a live website so as to help the owner update its content at its own having bare minimum knowledge about coding of the websites. It keeps websites well organised and comprehensive, increases the data security, and reduces the site maintenance costs. In this paper we present a review of some of the popular content management system packages.

  20. Line-Source Based X-Ray Tomography

    Directory of Open Access Journals (Sweden)

    Deepak Bharkhada

    2009-01-01

    Full Text Available Current computed tomography (CT scanners, including micro-CT scanners, utilize a point x-ray source. As we target higher and higher spatial resolutions, the reduced x-ray focal spot size limits the temporal and contrast resolutions achievable. To overcome this limitation, in this paper we propose to use a line-shaped x-ray source so that many more photons can be generated, given a data acquisition interval. In reference to the simultaneous algebraic reconstruction technique (SART algorithm for image reconstruction from projection data generated by an x-ray point source, here we develop a generalized SART algorithm for image reconstruction from projection data generated by an x-ray line source. Our numerical simulation results demonstrate the feasibility of our novel line-source based x-ray CT approach and the proposed generalized SART algorithm.

  1. Z - Source Multi Level Inverter Based PV Generation System

    Directory of Open Access Journals (Sweden)

    T. Lakhmi kanth

    2014-09-01

    Full Text Available In this paper a novel technique of Z-Source multilevel Inverter based PV Generation system is implemented and simulated using MATLAB-Simulink simulation software. The Photovoltaic cells are healthier option for converting solar energy into electricity. Due to high capital cost and low efficiency PV cells have not yet been a fully smart choice for electricity users. To enhance the performance of the system, Z-Source multi level inverter can be used in place of conventional Voltage Source Inverter (VSI in Solar Power Generation System. The PV cell model is developed using circuit mathematical equations. The Z-Source multilevel inverter is modeled to realize boosted DC to AC conversion (inversion with low THD. Outcome shows that the energy conversion efficiency of ZSMLI is a lot improved as compared to conventional voltage Source Inverter (VSI. By doing FFT analysis we can know the total THD.

  2. Source depth estimation based on synthetic aperture beamfoming for a moving source.

    Science.gov (United States)

    Yang, T C

    2015-09-01

    A continuous wave signal received on a single hydrophone from a moving source is beamformed using the synthetic aperture created by the source, where the signal at each range is steered by a range-dependent phase, relative to the starting point. The range increment (aperture) is determined based on the Doppler shift estimated from the data, knowing the original signal frequency. Given a sufficient signal-to-noise ratio, the source depth can be estimated from the beam output, assuming knowledge of the mode depth functions based on the nominal sound speed and bottom profile in the area. The method is illustrated with simulated data and at-sea data. For real data, the signal phase contains a random, incoherent component caused by the (random) source motion and media fluctuations in addition to the deterministic range-dependent component due to source range change. A phase locked loop is introduced to remove the random component assuming that the random component fluctuates faster with time than the range-dependent phase. When a vertical array of receivers are available covering the depth span of interest, the beam output can be used directly to estimate the source depth. In this case, no knowledge of the acoustic environment is needed. PMID:26428805

  3. IS1111 insertion sequences of Coxiella burnetii: characterization and use for repetitive element PCR-based differentiation of Coxiella burnetii isolates

    Directory of Open Access Journals (Sweden)

    Massung Robert F

    2007-10-01

    Full Text Available Abstract Background Coxiella burnetii contains the IS1111 transposase which is present 20 times in the Nine Mile phase I (9Mi/I genome. A single PCR primer that binds to each IS element, and primers specific to a region ~500-bp upstream of each of the 20 IS1111 elements were designed. The amplified products were characterized and used to develop a repetitive element PCR genotyping method. Results Isolates Nine Mile phase II, Nine Mile RSA 514, Nine Mile Baca, Scottish, Ohio, Australian QD, Henzerling phase I, Henzerling phase II, M44, KAV, PAV, Q238, Q195 and WAV were tested by PCR and compared to 9Mi/I. Sequencing was used to determine the exact differences in isolates which lacked specific IS elements or produced PCR products of differing size. From this data, an algorithm was created utilizing four primer pairs that allows for differentiation of unknown isolates into five genomic groups. Additional isolates (Priscilla Q177, Idaho Q, Qiyi, Poker Cat, Q229 and Q172 and nine veterinary samples were characterized using the algorithm which resulted in their placement into three distinct genomic groups. Conclusion Through this study significant differences, including missing elements and sequence alterations within and near IS element coding regions, were found between the isolates tested. Further, a method for differentiation of C. burnetii isolates into one of five genomic groups was created. This algorithm may ultimately help to determine the relatedness between known and unknown isolates of C. burnetii.

  4. Upper arm elevation and repetitive shoulder movements

    DEFF Research Database (Denmark)

    Dalbøge, Annett; Hansson, Gert-Åke; Frost, Poul;

    2016-01-01

    OBJECTIVES: We recently constructed a general population job exposure matrix (JEM), The Shoulder JEM, based on expert ratings. The overall aim of this study was to convert expert-rated job exposures for upper arm elevation and repetitive shoulder movements to measurement scales. METHODS: The...... Spearman rank correlations and the explained variance[Formula: see text] according to linear regression analyses (36 job groups). We used the linear regression equations to convert the expert-rated job exposures for all 172 job groups into predicted measured job exposures. Bland-Altman analyses were used...

  5. XML-based Components for Federating Multiple Heterogeneous Data Sources

    OpenAIRE

    Gardarin, Georges; Sha, Fei; Dang-Ngoc, Tuyet-Tram

    1999-01-01

    Several federated database systems have been built in the past using the relational or the object model as federating model. This paper gives an overview of the XMLMedia system, a federated database system mediator using XML as federating model, built in the Esprit Project MIRO-Web. The system is composed of four main components: a wrapper generator using rule-based scripting to produce XML data from various source formats, a mediator querying and integrating relational and XML sources, an XM...

  6. Six transformer based asymmetrical embedded Z-source inverters

    DEFF Research Database (Denmark)

    Wei, Mo; Poh Chiang, Loh; Chi, Jin;

    2013-01-01

    Embedded/Asymmetrical embedded Z-source inverters were proposed to maintain smooth input current/voltage across the dc source and within the impedance network, remain the shoot-through feature used to boost up the dc-link voltage without adding bulky filter at input side. This paper introduces a ...... a class of transformer based asymmetrical embedded Z-source inverters which keep the smooth input current and voltage while achieving enhanced voltage boost capability. The presented inverters are verified by laboratory prototypes experimentally....

  7. Grade repetition in primary school from teachers’ perspective

    Directory of Open Access Journals (Sweden)

    Malinić Dušica

    2011-01-01

    Full Text Available School underachievement is exhibited gradually, in different forms, while grade repetition figures as one of the most prominent forms of underachievement. In order to observe this phenomenon from different perspectives, we conducted a research aimed at identifying teacher attitudes towards grade repetition and grade repeaters in primary school, based on their perceptions of: (a the cause of grade repetition; (b the responsibility for grade repetition and (c grade repetition as an educational measure. The administered questionnaire was constructed for the purposes of the research, descriptive statistics was used, and data were obtained on the sample of 136 teachers from 31 primary schools from the territory of the City of Belgrade. The results point out to the conclusion that teachers perceive grade repetition as, first and foremost, the consequence of students’ lack of interest in school and learning and undisciplined behavior in class. By treating student underachievement mainly as a consequence of laziness, lack of motivation and insufficient effort, teachers transfer responsibility to others, assessing that the personal degree of responsibility for the underachievement of their students is very low. The responsibility for underachievement is perceived more as a problem of the student, his/her family, peer group, than as the problem of teachers themselves. The concluding part points out to certain teaching procedures and methods that have proved to be useful in the prevention of student underachievement.

  8. Demonstration of a high repetition rate capillary discharge waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Gonsalves, A. J., E-mail: ajgonsalves@lbl.gov; Pieronek, C.; Daniels, J.; Bulanov, S. S.; Waldron, W. L.; Mittelberger, D. E.; Leemans, W. P. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Liu, F.; Antipov, S.; Butler, J. E. [Euclid TechLabs, Gaithersburg, Maryland 20879 (United States); Bobrova, N. A.; Sasorov, P. V. [Keldysh Institute of Applied Mathematics, Moscow (Russian Federation)

    2016-01-21

    A hydrogen-filled capillary discharge waveguide operating at kHz repetition rates is presented for parameters relevant to laser plasma acceleration (LPA). The discharge current pulse was optimized for erosion mitigation with laser guiding experiments and MHD simulation. Heat flow simulations and measurements showed modest temperature rise at the capillary wall due to the average heat load at kHz repetition rates with water-cooled capillaries, which is promising for applications of LPAs such as high average power radiation sources.

  9. Piezoelectric-based hybrid reserve power sources for munitions

    Science.gov (United States)

    Rastegar, Jahangir; Pereira, Carlos M.; Feng, Dake

    2016-05-01

    Reserve power sources are used extensively in munitions and other devices such as emergency devices or remote sensors that have to be powered only once and for a relatively short duration. Current chemical reserve power sources, including thermal batteries and liquid reserve batteries require sometimes in excess of 100 msec to become fully activated. In many applications, however, electrical energy is required in a few msec following the launch event. In such applications, other power sources have to be provided to provide power until the reserve battery is fully activated. The amount of electrical energy that is required by most munitions before chemical reserve batteries are fully activated is generally small and can be provided by properly designed piezoelectric-based energy harvesting devices. In this paper the development of a hybrid reserve power source obtained by the integration of a piezoelectric-based energy harvesting device with a reserve battery that can provide power almost instantaneously upon munitions firing or other similar events is being reported. A review of the state of the art in piezoelectric-based electrical energy harvesting methods and devices and their charge collection electronics for use in the developed hybrid power sources is also provided together with the results of testing of the piezoelectric component of the power source and its electronic safety and charge collection electronics.

  10. Data-based matched-mode source localization for a moving source.

    Science.gov (United States)

    Yang, T C

    2014-03-01

    A data-based matched-mode source localization method is proposed in this paper for a moving source, using mode wavenumbers and depth functions estimated directly from the data, without requiring any environmental acoustic information and assuming any propagation model. The method is in theory free of the environmental mismatch problem because the mode replicas are estimated from the same data used to localize the source. Besides the estimation error due to the approximations made in deriving the data-based algorithms, the method has some inherent drawbacks: (1) It uses a smaller number of modes than theoretically possible because some modes are not resolved in the measurements, and (2) the depth search is limited to the depth covered by the receivers. Using simulated data, it is found that the performance degradation due to the afore-mentioned approximation/limitation is marginal compared with the original matched-mode source localization method. The proposed method has a potential to estimate the source range and depth for real data and be free of the environmental mismatch problem, noting that certain aspects of the (estimation) algorithms have previously been tested against data. The key issues are discussed in this paper.

  11. Nonclassically paired photons from sources based on cold atoms

    Science.gov (United States)

    Głódź, Małgorzata; Janowicz, Maciej; Kowalski, Krzysztof; Szonert, Jerzy

    2015-01-01

    In this short review some essentials concerning creation and testing of nonclassically correlated photons (biphotons) are given. In the introduction we remind the role which the experimentally produced entangled states have been playing for the foundations of the quantum physics, by witnessing against the model of local hidden variables. The well established sources of biphotons are based on spontaneous parametric down conversion in nonlinear crystals. A popular source with two BBO crystals is described, which generates pairs of photons nearly maximally entangled in polarization. Crystalbased sources rely on intrinsically broadband transitions, therefore thus produced biphotons are also broadband. Additional efforts (like applying optical cavities) are needed to reach narrowband biphotons which would comply with the requirements of some implementations in the quantum communication science. The topical issue of our article is a review of another, more recent approaches based on narrowband transitions between levels in cold atoms. Such method provides naturally narrowband biphotons. First, the principles are given of an atomic source of nonclassically paired photons, which is operated in a pulsed write-read mode. Such source is based on two separated in time Raman transitions triggered successively in two Λ-schemes. Next, cw-mode sources based (mainly) on spontaneous four wave mixing process (SFWM) are presented in a generic four-level scheme. Some underlying physics is sketched and profiles of biphoton correlation functions in the time domain are explained. Among other presented SFWM sources, one proves in testing high degree entanglement of generated biphotons, both in time-frequency and polarization (hyperentanglement).

  12. High-power mid-infrared frequency comb source based on a femtosecond Er:fiber oscillator.

    Science.gov (United States)

    Zhu, Feng; Hundertmark, Holger; Kolomenskii, Alexandre A; Strohaber, James; Holzwarth, Ronald; Schuessler, Hans A

    2013-07-01

    We report on a high-power mid-infrared (MIR) frequency comb source based on a femtosecond (fs) Er:fiber oscillator with a stabilized repetition rate of 250 MHz. The MIR frequency comb is produced through difference frequency generation in a periodically poled MgO-doped lithium niobate crystal. The output power is about 120 mW, with a pulse duration of about 80 fs and spectrum coverage from 2.9 to 3.6 μm, and the single comb mode power is larger than 0.3 μW over the range of 700 nm. The coherence properties of the produced high-power broadband MIR frequency comb are maintained, which was verified by heterodyne measurements. As the first application, the spectrum of a ~200 ppm methane-air mixture in a short 20 cm glass cell at ambient atmospheric pressure and temperature was measured. PMID:23811928

  13. High-power mid-infrared frequency comb source based on a femtosecond Er:fiber oscillator

    CERN Document Server

    Zhu, Feng; Kolomenskii, Alexandre A; Strohaber, James; Holzwarth, Ronald; Schuessler, Hans A

    2013-01-01

    We report on a high-power mid-infrared frequency comb source based on a femtosecond Er:fiber oscillator with a stabilized repetition rate at 250 MHz. The mid-infrared frequency comb is produced through difference frequency generation in a periodically poled MgO-doped lithium niobate crystal. The output power is about 120 mW with a pulse duration of about 80 fs, and spectrum coverage from 2.9 to 3.6 um. The coherence properties of the produced high-power broadband mid-infrared frequency comb are maintained, which was verified by heterodyne measurements. As the first application, the spectrum of a ~200 ppm methane-air mixture in a short 20 cm glass cell at ambient atmospheric pressure and temperature was measured.

  14. Phased-array sources based on nonlinear metamaterial nanocavities.

    Science.gov (United States)

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P; Liu, Sheng; Luk, Ting S; Kadlec, Emil A; Shaner, Eric A; Klem, John F; Sinclair, Michael B; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  15. A Parallax-based Distance Estimator for Spiral Arm Sources

    CERN Document Server

    Reid, M J; Menten, K M; Brunthaler, A

    2016-01-01

    The spiral arms of the Milky Way are being accurately located for the first time via trigonometric parallaxes of massive star forming regions with the BeSSeL Survey, using the Very Long Baseline Array and the European VLBI Network, and with the Japanese VERA project. Here we describe a computer program that leverages these results to significantly improve the accuracy and reliability of distance estimates to other sources that are known to follow spiral structure. Using a Bayesian approach, sources are assigned to arms based on their (l,b,v) coordinates with respect to arm signatures seen in CO and HI surveys. A source's kinematic distance, displacement from the plane, and proximity to individual parallax sources are also considered in generating a full distance probability density function. Using this program to estimate distances to large numbers of star forming regions, we generate a realistic visualization of the Milky Way's spiral structure as seen from the northern hemisphere.

  16. Intensive neutrino source on the base of lithium converter

    CERN Document Server

    Lyashuk, V I

    2015-01-01

    An intensive antineutrino source with a hard spectrum (with energy up to 13 MeV, average energy 6.5 MeV) can be realized on the base of beta-decay of short living isotope 8Li (0.84 s). The 8Li isotope (generated in activation of 7Li isotope) is a prime perspective antineutrino source owing to the hard antineutrino spectrum and square dependence of cross section on the energy. Up today nuclear reactors are the most intensive neutrino sources. Antineutrino reactor spectra have large uncertainties in the summary antineutrino spectrum at energy E>6 MeV. Use of 8Li isotope allows to decrease sharply the uncertainties or to exclude it completely. An intensive neutron fluxes are requested for rapid generation of 8Li isotope. The installations on the base of nuclear reactors can be an alternative for nuclear reactors as traditional neutron sources. It is possible creation of neutrino sources another in principle: on the base of tandem of accelerators, neutron generating targets and lithium converter. An intensive neu...

  17. High repetition rate intense ion beam diode

    International Nuclear Information System (INIS)

    A magnetically insulated ion beam diode with a gas-breakdown plasma anode has been successfully developed recently. In this paper, the authors report the experiment results of operating a version of this diode at a 1-Hz repetition rate. Intense ion beams (100ns, 200Kv and 20kA per pulse) are generated by using an inductive voltage to breakdown an annular hydrogen gas puff (8.5cm mean radius, and 160cm2 in area), and magnetically driving the resulting plasma toward a magnetically insulated accelerating gap. The high voltage pulses on the accelerating gap are supplied using two thyratron switch chassises which are connected to the diode through a series of capacitors coupled with saturable inductors. To understand the operation of the diode, the anode plasma source and the extracted ion beams are characterized by using various diagnostics

  18. Detection of Explosives by Using a Neutron Source Based on a Proton Linac

    CERN Document Server

    Dolya, S N

    2016-01-01

    The paper considers an opportunity of detecting explosives by using radiation capture of a neutron with nitrogen nucleus. Proton LINAC is offered as the neutron source with the following parameters: proton energy five Mega electron Volts , beam pulse current one and seven-tenths milliampere, duration of the current pulse two hundreds microseconds, repetition rate fifty Hertz. The reaction in which neutrons are formed is lithium (p,n) beryllium. It is shown that this neutron source will have the intensity of ten to the twelfth degree neutron per second that will allow one to detect explosives of the size of a tennis ball.

  19. Note: Localization based on estimated source energy homogeneity

    Science.gov (United States)

    Turkaya, Semih; Toussaint, Renaud; Eriksen, Fredrik Kvalheim; Lengliné, Olivier; Daniel, Guillaume; Flekkøy, Eirik G.; Mâløy, Knut Jørgen

    2016-09-01

    Acoustic signal localization is a complex problem with a wide range of industrial and academic applications. Herein, we propose a localization method based on energy attenuation and inverted source amplitude comparison (termed estimated source energy homogeneity, or ESEH). This inversion is tested on both synthetic (numerical) data using a Lamb wave propagation model and experimental 2D plate data (recorded with 4 accelerometers sensitive up to 26 kHz). We compare the performance of this technique with classic source localization algorithms: arrival time localization, time reversal localization, and localization based on energy amplitude. Our technique is highly versatile and out-performs the conventional techniques in terms of error minimization and cost (both computational and financial).

  20. Status of the Linac based positron source at Saclay

    CERN Document Server

    Rey, J -M; Debu, P; Dzitko, H; Hardy, P; Liszkay, L; Lotrus, P; Muranaka, T; Noel, C; Perez, P; Pierret, O; Ruiz, N; Sacquin, Y

    2013-01-01

    Low energy positron beams are of major interest for fundamental science and materials science. IRFU has developed and built a slow positron source based on a compact, low energy (4.3 MeV) electron linac. The linac-based source will provide positrons for a magnetic storage trap and represents the first step of the GBAR experiment (Gravitational Behavior of Antimatter in Rest) recently approved by CERN for an installation in the Antiproton Decelerator hall. The installation built in Saclay will be described with its main characteristics. The ultimate target of the GBAR experiment will be briefly presented as well as the foreseen development of an industrial positron source dedicated for materials science laboratories.

  1. Based on the UC3825 chip repetition frequency laser power supply design and research%基于UC3825芯片重频激光电源设计与研究

    Institute of Scientific and Technical Information of China (English)

    陈景忠

    2012-01-01

    随着微电子技术和电子电力技术的不断发展,高频开关稳压电源正以体积小、效率高等优点而广泛应用于各种军用、民用仪器仪表、控制设备产品中。激光电源作为一种特殊开关电源,和普通开关电源的区别是负载伏安特性完全不同,本文主要介绍了一种基于UC3825芯片的重复频率激光电源的工作原理,它采用半桥式变换电路,利用UC3825进行电流型调制,用IR2110双通道驱动芯片驱动场效应管,采用单片机AT89C51组成的控制电路对脉冲激光氙灯进行重复频率充放电控制,最终成功实现了一种基于UC3825芯片的重复频率激光电源的研制。%With microelectronic technology and power electronic technology development, high frequency switching power supply with small volume, high efficiency, etc. are widely used in various military, civilian insmunents, control equipment products. Laser power as a kind of special switching power supply, switching power supply and the common difference is load volt - ampere characteristics are quite different, this paper mainly introduces one kind based on the UC3825 chip repetition frequency laser power supply works, which utilizes half- bridge converter circuit, using UC3825 electric cun'ent modulation, using IR2110 dual channel driving chip driving FET, the single chip microcomputer AT89C.51 control circuit composed of a pulse laser repetitive frequency of xenon lamp charging and discharging control, ultimately the suecesafitl implementation of the one kind based on the UC3825 chip repetition frequency laser power supply.

  2. Repetitively pulsed power for meat pasteurization

    International Nuclear Information System (INIS)

    Electronic pasteurization of meat offers the potential for drastically reducing the incidence of food poisoning caused by biological pathogens accidentally introduced into meat products. Previous work has shown that γ-rays are an effective method of destroying E. coli 0157:H7, Salmonella, C. jejuni, L. monocytogenes, Listeria, and S. aureus bacteria types. The concern with the use of γ-rays is that radioactive material must be used in the pasteurization process that can lead to some market resistance and activist pressure on the meat industry. The use of accelerator generated high average power electron beams, at energies less than 10 MeV, or X-rays, with energies below 5 MeV, have been approved by the FDA for use in pasteurizing foods. Accelerator produced electronic pasteurization has the advantage that no radioactive material inventory is required. Electronic pasteurization has the additional benefit that it removes bacterial pathogens on the meat surface as well as within the volume of the meat product. High average power, repetitively-pulsed, broad-area electron beam sources being developed in the RHEPP program are suitable for large scale meat treatment in packing plant environments. RHEPP-II, which operates at 2.5 MeV and 25 kA at pulse repetition frequencies up to 120 Hz has adequate electron energy to penetrate hamburger patties which comprise about half of the beef consumption in the United States. Ground beef also has the highest potential for contamination since considerable processing is required in its production. A meat pasteurization facility using this size of accelerator source should be capable of treating 106 pounds of hamburger patties per hour to a dose of up to 3 kGy (300 kilorads). The RHEPP modular accelerator technology can easily be modified for other production rates and types of products

  3. Solving Information-Based Problems: Evaluating Sources and Information

    Science.gov (United States)

    Brand-Gruwel, Saskia; Stadtler, Marc

    2011-01-01

    The focus of this special section is on the processes involved when solving information-based problems. Solving these problems requires from people that they are able to define the information problem, search and select usable and reliable sources and information and synthesise information into a coherent body of knowledge. An important aspect…

  4. High brightness single photon sources based on photonic wires

    DEFF Research Database (Denmark)

    Claudon, J.; Bleuse, J.; Bazin, M.;

    2009-01-01

    We present a novel single-photon-source based on the emission of a semiconductor quantum dot embedded in a single-mode photonic wire. This geometry ensures a very large coupling (> 95%) of the spontaneous emission to the guided mode. Numerical simulations show that a photon collection efficiency as...

  5. Fast Tunable Wavelength Sources Based on the Laser Diode Array

    Institute of Scientific and Technical Information of China (English)

    Sung-Chan; Cho; Hyun; Ha; Hong; Byoung-Whi; Kim

    2003-01-01

    We report a demonstration of a fast wavelength tunable source (TWS) based on the laser diode array coupled to the arrayed waveguide grating (AWG) multiplexer. The switching and optical characteristics of TWS make it a candidate for implementing the wavelength-division space switch fabric for an optical packet/burst switching.

  6. Repetitively pulsed material testing facility

    International Nuclear Information System (INIS)

    A continuously operated, 1 pps, dense-plasma-focus device capable of delivering a minimum of 1015 neutrons per pulse for material testing purposes is described. Moderate scaling from existing results is sufficient to provide 2 x 1013 n/cm2.s to a suitable target. The average power consumption, which has become a major issue as a result of the energy crisis, is analyzed with respect to other plasma devices and is shown to be highly favorable. A novel approach to the capacitor bank and switch design allowing repetitive operation is discussed. (U.S.)

  7. 重复控制的开关磁阻电机转矩脉动抑制策略%Repetitive Control Based Torque Ripple Reduction Strategy for SRM

    Institute of Scientific and Technical Information of China (English)

    刘作军; 常硕; 董砚; 郑易

    2013-01-01

    针对开关磁阻电机在运行中的转矩脉动问题,提出了一种基于重复控制的开关磁阻电机转矩脉动抑制方法.在具有周期性扰动的控制系统中,重复控制把上一周期的偏差和当前的偏差叠加到被控对象进行控制,以达到高精度的控制效果.在此策略基础上,通过转子位置角估算和滞环电流控制,合理调节转矩大小,使电机转矩在运行中平稳过渡,从而达到抑制其转矩脉动的效果.仿真证实该方法能够有效地抑制开关磁阻电机的转矩脉动.%To reduce the torque ripple in switched reluctance motor,a strategy based on repetitive control was proposed.In the system with periodic disturbance,repetitive control can obtain high precision in the way of inputting the sum of error in the present period and the last period.Based on this strategy,the torque of SRM could be adjusted with rotator position and current hysteresis-band control to make the motor running smoothly.And high torque ripple control performance was obtained.Simulation and experiment prove the effect in reducing torque ripple of SRM.

  8. Nearfield acoustic holography based on the equivalent source method

    Institute of Scientific and Technical Information of China (English)

    BI Chuanxing; CHEN Xinzhao; CHEN Jian; ZHOU Rong

    2005-01-01

    On the basis of the nearfield acoustic holography (NAH) based on the distributed source boundary point method (DSBPM), a novel NAH based on the equivalent source method (ESM) is proposed. The theoretical model of the proposed method is established at first. And then, the error sensitivity and the reconstruction problems of a multi-source acoustic field and a semi-free acoustic field are analyzed, and the corresponding treatment methods are proposed. Subsequently, an experiment on a speaker is investigated to validate the feasibility and correctness of the method. In the method, no discretization is needed on the boundary of the vibrating body. The acoustic field is predicted directly by a set of weighted equivalent sources located inside the vibrating body. Therefore, the variable interpolation, the treatments of singular integrals and non-uniqueness of solutions in the characteristic wave number are avoided. Additionally, the method is adapted to arbitrary-shaped source, so it is really a meshless method. Furthermore, there are such merits as the simple principle, the high calculation efficiency and precision. It is valuabe for the NAH to be applied in the practical engineering field.

  9. GRAPE - GIS Repetition Using Audio-Visual Repetition Units and its Leanring Effectiveness

    Science.gov (United States)

    Niederhuber, M.; Brugger, S.

    2011-09-01

    A new audio-visual learning medium has been developed at the Department of Environmental Sciences at ETH Zurich (Switzerland), for use in geographical information sciences (GIS) courses. This new medium, presented in the form of Repetition Units, allows students to review and consolidate the most important learning concepts on an individual basis. The new material consists of: a) a short enhanced podcast (recorded and spoken slide show) with a maximum duration of 5 minutes, which focuses on only one important aspect of a lecture's theme; b) one or two relevant exercises, covering different cognitive levels of learning, with a maximum duration of 10 minutes; and c), solutions for the exercises. During a pilot phase in 2010, six Repetition Units were produced by the lecturers. Twenty more Repetition Units will be produced by our students during the fall semester of 2011 and 2012. The project is accompanied by a 5-year study (2009 - 2013) that investigates learning success using the new material, focussing on the question, whether or not the new material help to consolidate and refresh basic GIS knowledge. It will be analysed based on longitudinal studies. Initial results indicate that the new medium helps to refresh knowledge as the test groups scored higher than the control group. These results are encouraging and suggest that the new material with its combination of short audio-visual podcasts and relevant exercises help to consolidate students' knowledge.

  10. Pixel-based ant colony algorithm for source mask optimization

    Science.gov (United States)

    Kuo, Hung-Fei; Wu, Wei-Chen; Li, Frederick

    2015-03-01

    Source mask optimization (SMO) was considered to be one of the key resolution enhancement techniques for node technology below 20 nm prior to the availability of extreme-ultraviolet tools. SMO has been shown to enlarge the process margins for the critical layer in SRAM and memory cells. In this study, a new illumination shape optimization approach was developed on the basis of the ant colony optimization (ACO) principle. The use of this heuristic pixel-based ACO method in the SMO process provides an advantage over the extant SMO method because of the gradient of the cost function associated with the rapid and stable searching capability of the proposed method. This study was conducted to provide lithographic engineers with references for the quick determination of the optimal illumination shape for complex mask patterns. The test pattern used in this study was a contact layer for SRAM design, with a critical dimension and a minimum pitch of 55 and 110 nm, respectively. The optimized freeform source shape obtained using the ACO method was numerically verified by performing an aerial image investigation, and the result showed that the optimized freeform source shape generated an aerial image profile different from the nominal image profile and with an overall error rate of 9.64%. Furthermore, the overall average critical shape difference was determined to be 1.41, which was lower than that for the other off-axis illumination exposure. The process window results showed an improvement in exposure latitude (EL) and depth of focus (DOF) for the ACO-based freeform source shape compared with those of the Quasar source shape. The maximum EL of the ACO-based freeform source shape reached 7.4% and the DOF was 56 nm at an EL of 5%.

  11. High-brightness source based on luminescent concentration.

    Science.gov (United States)

    de Boer, Dick K G; Bruls, Dominique; Jagt, Henri

    2016-07-11

    The concept of a high-luminance light source based on luminescent conversion of LED light and optical concentration in a transparent phosphor is explained. Experiments on a realized light source show that a luminous flux of 8500 lm and a luminance of 500 cd/mm2 can be attained using 56 pump LEDs at 330 W electrical input power. The measurement results are compared to optical simulations, showing that the experimental optical efficiency is slightly lower than expected. The present status enables applications like mid-segment digital projection using LED technology, whereas the concept is scalable to higher fluxes. PMID:27410894

  12. Laser wakefield accelerator based light sources: potential applications and requirements

    Energy Technology Data Exchange (ETDEWEB)

    Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). NIF and Photon Sciences; Thomas, A. G. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Mangles, S. P.D. [Imperial College, London (United Kingdom). Blackett Lab.; Banerjee, S. [Univ. of Nebraska, Lincoln, NE (United States); Corde, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Flacco, A. [ENSTA, CNRS, Ecole Polytechnique, Palaiseau (France); Litos, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neely, D. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Viera, J. [Univ. of Lisbon (Portugal). GoLP-Inst. de Plasmas e Fusao Nuclear-Lab. Associado; Najmudin, Z. [Imperial College, London (United Kingdom). Blackett Lab.; Bingham, R. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Joshi, C. [Univ. of California, Los Angeles, CA (United States). Dept. of Electrical Engineering; Katsouleas, T. [Duke Univ., Durham, NC (United States). Platt School of Engineering

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  13. Repeated text in unrelated passages: Repetition versus meaning selection effects.

    Science.gov (United States)

    Klin, Celia M; Drumm, April M; Ralano, Angela S

    2009-07-01

    Despite previous findings, Klin, Ralano, and Weingartner (2007) found transfer benefits across unrelated passages. After processing an ambiguous phrase in Story A that was biased toward its sarcastic meaning, readers were more likely to interpret the identical phrase in Story B as sarcastic, even though it contained no disambiguating information. In the present experiments, we found both repetition effects (a benefit for the lexical items) and meaning selection effects (a benefit for the selected meaning of the phrase) with short delays between Stories A and B; with longer delays, only repetition effects were found. Whereas decreasing the elaboration of the phrase eliminated both effects, moving the disambiguating context from before to after the phrase eliminated meaning selection effects only. We conclude that meaning selection effects, which are based on conceptual overlap, are more sensitive to context changes and less robust than repetition effects, which are based on both perceptual and conceptual overlap.

  14. Laser air-jet engine: the action of shock waves at low laser pulse repetition rates

    International Nuclear Information System (INIS)

    The impact and thermal action of laser sparks on the reflector of a laser engine in which the propulsion is produced by repetitively pulsed radiation is estimated. It is shown that for a low pulse repetition rate, the thermal contact of a plasma with the reflector and strong dynamic resonance loads are inevitable. These difficulties can be surmounted by using the method based on the merging of shock waves at a high pulse repetition rate. (laser applications)

  15. Open Source Web Based Geospatial Processing with OMAR

    Directory of Open Access Journals (Sweden)

    Mark Lucas

    2009-01-01

    Full Text Available The availability of geospatial data sets is exploding. New satellites, aerial platforms, video feeds, global positioning system tagged digital photos, and traditional GIS information are dramatically increasing across the globe. These raw materials need to be dynamically processed, combined and correlated to generate value added information products to answer a wide range of questions. This article provides an overview of OMAR web based geospatial processing. OMAR is part of the Open Source Software Image Map project under the Open Source Geospatial Foundation. The primary contributors of OSSIM make their livings by providing professional services to US Government agencies and programs. OMAR provides one example that open source software solutions are increasingly being deployed in US government agencies. We will also summarize the capabilities of OMAR and its plans for near term development.

  16. Commissioning of a Compton-Scattering-Based Gamma Ray Source

    Science.gov (United States)

    Gibson, David; Albert, Felicie; Anderson, Scott; Hartemann, Fred; Messerly, Mike; Shverdin, Miro; McNabb, Dennis; Siders, Craig; Barty, Chris

    2009-11-01

    Recently a Compton-scattering based gamma-ray source, in which a high-intensity laser scatters off a high-brightness electron beam and emerges as a narrow-band gamma-ray beam, has been commissioned at Lawrence Livermore National Laboratory. Operating at energies from 0.1 to 0.9 MeV, the source produces fluxes upwards of 10^6 photons/sec with a brightness of 10^ 15 photons/s/mm^2/mrad^2/0.1% BW. Presented here is a discussion of the design and performance of the laser and electron subsystems that are used to drive the source, and an overview of the parameters of the generated gamma-ray beam.

  17. Optimal Source-Based Filtering of Malicious Traffic

    CERN Document Server

    Soldo, Fabio; Markopoulou, Athina

    2010-01-01

    In this paper, we consider the problem of blocking malicious traffic on the Internet, via source-based filtering. In particular, we consider filtering via access control lists (ACLs): these are already available at the routers today but are a scarce resource because they are stored in the expensive ternary content addressable memory (TCAM). Aggregation (by filtering source prefixes instead of individual IP addresses) helps reduce the number of filters, but comes also at the cost of blocking legitimate traffic originating from the filtered prefixes. We show how to optimally choose which source prefixes to filter, for a variety of realistic attack scenarios and operators' policies. In each scenario, we design optimal, yet computationally efficient, algorithms. Using logs from Dshield.org, we evaluate the algorithms and demonstrate that they bring significant benefit in practice.

  18. Energy-Based Collaborative Source Localization Using Acoustic Microsensor Array

    Directory of Open Access Journals (Sweden)

    Li Dan

    2003-01-01

    Full Text Available A novel sensor network source localization method based on acoustic energy measurements is presented. This method makes use of the characteristics that the acoustic energy decays inversely with respect to the square of distance from the source. By comparing energy readings measured at surrounding acoustic sensors, the source location during that time interval can be accurately estimated as the intersection of multiple hyperspheres. Theoretical bounds on the number of sensors required to yield unique solution are derived. Extensive simulations have been conducted to characterize the performance of this method under various parameter perturbations and noise conditions. Potential advantages of this approach include low intersensor communication requirement, robustness with respect to parameter perturbations and measurement noise, and low-complexity implementation.

  19. Resource management tools based on renewable energy sources

    Science.gov (United States)

    Jannson, Tomasz; Forrester, Thomas; Boghrat, Pedram; Pradhan, Ranjit; Kostrzewski, Andrew

    2012-06-01

    Renewable energy is an important source of power for unattended sensors (ground, sea, air), tagging systems, and other remote platforms for Homeland Security and Homeland Defense. Also, Command, Control, Communication, and Intelligence (C3I) systems and technologies often require renewable energy sources for information assurance (IA), in general, and anti-tampering (AT), in particular. However, various geophysical and environmental conditions determine different types of energy harvesting: solar, thermal, vibration, acoustic, hydraulic, wind, and others. Among them, solar energy is usually preferable, but, both a solar habitat and the necessity for night operation can create a need for other types of renewable energy. In this paper, we introduce figures of merit (FoMs) for evaluating preferences of specific energy sources, as resource management tools, based on geophysical conditions. Also, Battery Systemic Modeling is discussed.

  20. Alternative modeling methods for plasma-based Rf ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Veitzer, Seth A., E-mail: veitzer@txcorp.com; Kundrapu, Madhusudhan, E-mail: madhusnk@txcorp.com; Stoltz, Peter H., E-mail: phstoltz@txcorp.com; Beckwith, Kristian R. C., E-mail: beckwith@txcorp.com [Tech-X Corporation, Boulder, Colorado 80303 (United States)

    2016-02-15

    Rf-driven ion sources for accelerators and many industrial applications benefit from detailed numerical modeling and simulation of plasma characteristics. For instance, modeling of the Spallation Neutron Source (SNS) internal antenna H{sup −} source has indicated that a large plasma velocity is induced near bends in the antenna where structural failures are often observed. This could lead to improved designs and ion source performance based on simulation and modeling. However, there are significant separations of time and spatial scales inherent to Rf-driven plasma ion sources, which makes it difficult to model ion sources with explicit, kinetic Particle-In-Cell (PIC) simulation codes. In particular, if both electron and ion motions are to be explicitly modeled, then the simulation time step must be very small, and total simulation times must be large enough to capture the evolution of the plasma ions, as well as extending over many Rf periods. Additional physics processes such as plasma chemistry and surface effects such as secondary electron emission increase the computational requirements in such a way that even fully parallel explicit PIC models cannot be used. One alternative method is to develop fluid-based codes coupled with electromagnetics in order to model ion sources. Time-domain fluid models can simulate plasma evolution, plasma chemistry, and surface physics models with reasonable computational resources by not explicitly resolving electron motions, which thereby leads to an increase in the time step. This is achieved by solving fluid motions coupled with electromagnetics using reduced-physics models, such as single-temperature magnetohydrodynamics (MHD), extended, gas dynamic, and Hall MHD, and two-fluid MHD models. We show recent results on modeling the internal antenna H{sup −} ion source for the SNS at Oak Ridge National Laboratory using the fluid plasma modeling code USim. We compare demonstrate plasma temperature equilibration in two

  1. Alternative modeling methods for plasma-based Rf ion sources.

    Science.gov (United States)

    Veitzer, Seth A; Kundrapu, Madhusudhan; Stoltz, Peter H; Beckwith, Kristian R C

    2016-02-01

    Rf-driven ion sources for accelerators and many industrial applications benefit from detailed numerical modeling and simulation of plasma characteristics. For instance, modeling of the Spallation Neutron Source (SNS) internal antenna H(-) source has indicated that a large plasma velocity is induced near bends in the antenna where structural failures are often observed. This could lead to improved designs and ion source performance based on simulation and modeling. However, there are significant separations of time and spatial scales inherent to Rf-driven plasma ion sources, which makes it difficult to model ion sources with explicit, kinetic Particle-In-Cell (PIC) simulation codes. In particular, if both electron and ion motions are to be explicitly modeled, then the simulation time step must be very small, and total simulation times must be large enough to capture the evolution of the plasma ions, as well as extending over many Rf periods. Additional physics processes such as plasma chemistry and surface effects such as secondary electron emission increase the computational requirements in such a way that even fully parallel explicit PIC models cannot be used. One alternative method is to develop fluid-based codes coupled with electromagnetics in order to model ion sources. Time-domain fluid models can simulate plasma evolution, plasma chemistry, and surface physics models with reasonable computational resources by not explicitly resolving electron motions, which thereby leads to an increase in the time step. This is achieved by solving fluid motions coupled with electromagnetics using reduced-physics models, such as single-temperature magnetohydrodynamics (MHD), extended, gas dynamic, and Hall MHD, and two-fluid MHD models. We show recent results on modeling the internal antenna H(-) ion source for the SNS at Oak Ridge National Laboratory using the fluid plasma modeling code USim. We compare demonstrate plasma temperature equilibration in two-temperature MHD

  2. Robust Source Localization in Shallow Water Based on Vector Optimization

    Institute of Scientific and Technical Information of China (English)

    SONG Hai-yan; SHI Jie; LIU Bo-sheng

    2013-01-01

    Owing to the multipath effect,the source localization in shallow water has been an area of active interest.However,most methods for source localization in shallow water are sensitive to the assumed model of the underwater environment and have poor robustness against the underwater channel uncertainty,which limit their further application in practical engineering.In this paper,a new method of source localization in shallow water,based on vector optimization concept,is described,which is highly robust against environmental factors affecting the localization,such as the channel depth,the bottom reflection coefficients,and so on.Through constructing the uncertainty set of the source vector errors and extracting the multi-path sound rays from the sea surface and bottom,the proposed method can accurately localize one or more sources in shallow water dominated by multipath propagation.It turns out that the natural formulation of our approach involves minimization of two quadratic functions subject to infinitely many nonconvex quadratic constraints.It shows that this problem (originally intractable) can be reformulated in a convex form as the so-called second-order cone program (SOCP) and solved efficiently by using the well-established interior point method,such as the software tool,SeDuMi.Computer simulations show better performance of the proposed method as compared with existing algorithms and establish a theoretical foundation for the practical engineering application.

  3. Applications of laser wakefield accelerator-based light sources

    Science.gov (United States)

    Albert, Félicie; Thomas, Alec G. R.

    2016-11-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. We first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  4. Full characterization of self-phase-modulation based low-noise, cavity-less pulse source for photonic-assisted analog-to-digital conversion.

    Science.gov (United States)

    Liu, Lan; Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Alic, Nikola; Radic, Stojan

    2012-12-10

    A high quality cavity-less pulse source, realized as a combination of linear pulse compression and self-phase-modulation (SPM) based regeneration is demonstrated and strictly characterized for the first time. The regenerated pulses, with 3.6 GHz repetition rate, are optimized through rigorous relative intensity-noise (RIN) measurement. Temporal intensity and chirp characterizations demonstrate that the pulses exhibit characteristic of low RIN, and are chirp- and pedestal-free. The cavity-less pulse source is further tested in a photonic-assisted analog-to-digital (ADC) configuration as the sampling source. A record result of more than 8 effective quantization bits at 202 MHz is demonstrated. PMID:23262840

  5. S-band linac-based X-ray source with π/2-mode electron linac

    International Nuclear Information System (INIS)

    The activities with the compact X-ray source are attracting more attention, particularly for the applications of the source in medical fields. We propose the fabrication of a compact X-ray source using the SAMEER electron linear accelerator and the KEK laser undulator X-ray source (LUCX) technologies. The linac developed at SAMEER is a standing wave side-coupled S-band linac operating in the π/2 mode. In the proposed system, a photocathode RF gun will inject bunches of electrons in the linac to accelerate and achieve a high-energy, low-emittance beam. This beam will then interact with the laser in the laser cavity to produce X-rays of a type well suited for various applications. The side-coupled structure will make the system more compact, and the π/2 mode of operation will enable a high repetition rate operation, which will help to increase the X-ray yield.

  6. Composite repetition-aware data structures

    OpenAIRE

    Belazzougui, Djamal; Cunial, Fabio; Gagie, Travis; Prezza, Nicola; Raffinot, Mathieu

    2015-01-01

    In highly repetitive strings, like collections of genomes from the same species, distinct measures of repetition all grow sublinearly in the length of the text, and indexes targeted to such strings typically depend only on one of these measures. We describe two data structures whose size depends on multiple measures of repetition at once, and that provide competitive tradeoffs between the time for counting and reporting all the exact occurrences of a pattern, and the space taken by the struct...

  7. Repetitive sequence environment distinguishes housekeeping genes

    OpenAIRE

    Eller, C. Daniel; Regelson, Moira; Merriman, Barry; Nelson, Stan,; Horvath, Steve; Marahrens, York

    2006-01-01

    Housekeeping genes are expressed across a wide variety of tissues. Since repetitive sequences have been reported to influence the expression of individual genes, we employed a novel approach to determine whether housekeeping genes can be distinguished from tissue-specific genes their repetitive sequence context. We show that Alu elements are more highly concentrated around housekeeping genes while various longer (>400-bp) repetitive sequences ("repeats"), including Long Interspersed Nuclear E...

  8. Visible and ultraviolet light sources based nonlinear interaction of lasers

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Tidemand-Lichtenberg, Peter; Jain, Mayank;

    Different light sources can be used for optically stimulated luminescence measurements and usually a halogen lamp in combination with filters or light emitting diodes (LED’s) are used to provide the desired stimulation wavelength. However lasers can provide a much more well-defined beam, very...... for synthesizing any wavelength in the visible and ultraviolet light based sum frequency generation between two lasers is presented....

  9. Pressure rig for repetitive casting

    Science.gov (United States)

    Vasquez, Peter (Inventor); Hutto, William R. (Inventor); Philips, Albert R. (Inventor)

    1989-01-01

    The invention is a pressure rig for repetitive casting of metal. The pressure rig performs like a piston for feeding molten metal into a mold. Pressure is applied to an expandable rubber diaphragm which expands like a balloon to force the metal into the mold. A ceramic cavity which holds molten metal is lined with blanket-type insulating material, necessitating only a relining for subsequent use and eliminating the lengthy cavity preparation inherent in previous rigs. In addition, the expandable rubber diaphragm is protected by the insulating material thereby decreasing its vulnerability to heat damage. As a result of the improved design the life expectancy of the pressure rig contemplated by the present invention is more than doubled. Moreover, the improved heat protection has allowed the casting of brass and other alloys with higher melting temperatures than possible in the conventional pressure rigs.

  10. Conceptional Design of the Laser Ion Source based Hadrontherapy Facility

    CERN Document Server

    Xie, Xiucui; Zhang, Xiaohu

    2013-01-01

    Laser ion source (LIS), which can provide carbon beam with highly stripped state (C6+) and high intensity (several tens mA), would significantly change the overall design of the hadrontherapy facility. A LIS based hadrontherapy facility is proposed with the advantage of short linac length, simple injection scheme and small synchrotron size. With the experience from the DPIS and HITFiL project that had conducted in IMP, a conceptional design of the LIS based hadrontherapy facility will be present with special dedication to APF type IH DTL design and simulation.

  11. Conceptional design of the laser ion source based hadrontherapy facility

    Science.gov (United States)

    Xie, Xiu-Cui; Song, Ming-Tao; Zhang, Xiao-Hu

    2014-04-01

    A laser ion source (LIS), which can provide a carbon beam with highly stripped state (C6+) and high intensity (several tens mA), would significantly change the overall design of the hadrontherapy facility. The proposed LIS based hadrontherapy facility has the advantages of short linac length, simple injection scheme, and small synchrotron size. With the experience from the DPIS and HITFiL projects that have been conducted in IMP, a conceptional design of the LIS based hadrontherapy facility will be presented, with special attention given to APF type IH DTL design and simulation.

  12. 任务类型对不同SOA条件下基于颜色重复劣势效应的影响%The Effect of Task Type on Color-Based Repetition Disadvantage Effect in Different SOA Conditions

    Institute of Scientific and Technical Information of China (English)

    赵建宝; 王勇慧

    2014-01-01

    采用探测任务和辨别任务,分别考察了不同线索与目标呈现时间间隔( SOA )条件下出现的基于颜色的重复劣势效应( repe ition disadv antage,RD)。研究结果发现:探测任务下和辨别任务下出现基于颜色的 RD 效应分别倾向于解释为重复知盲现象和基于颜色的IOR效应。关于不同的任务类型对基于颜色的RD效应的影响,可以用特征个体化理论解释。实验3采用 Go/No go任务,通过进一步地分析提出任务类型背后,被试对目标刺激的语义加工水平才是影响基于颜色 RD效应抑制本质的关键因素。关于该因素对基于颜色重复劣势效应的影响,可以用评价窗口理论解释。%With different stimulus onset asynchrony ( SOA) , the effects of task type on color-based repetition disadvan-tage ( RD) effect were explored in 2 experiments.When the task type was detection task, the color-based RD effect is the repetition blindness in nature.However, when the task demand was color discrimination, the RD effect tend to be explained as the color-based inhibition of return.The results can be appropriately explained by the token indi-viduation theory.Further analysis, the author proposes that the level of semantic processing of target stimulus is the fundamental determinants.Experiment 3 was used to Go/No go task, the results showed color-based IOR as same as experiment 2 , which can be explained by the theory of “Evaluation Window Account”.

  13. Wavelet-based localization of oscillatory sources from magnetoencephalography data.

    Science.gov (United States)

    Lina, J M; Chowdhury, R; Lemay, E; Kobayashi, E; Grova, C

    2014-08-01

    Transient brain oscillatory activities recorded with Eelectroencephalography (EEG) or magnetoencephalography (MEG) are characteristic features in physiological and pathological processes. This study is aimed at describing, evaluating, and illustrating with clinical data a new method for localizing the sources of oscillatory cortical activity recorded by MEG. The method combines time-frequency representation and an entropic regularization technique in a common framework, assuming that brain activity is sparse in time and space. Spatial sparsity relies on the assumption that brain activity is organized among cortical parcels. Sparsity in time is achieved by transposing the inverse problem in the wavelet representation, for both data and sources. We propose an estimator of the wavelet coefficients of the sources based on the maximum entropy on the mean (MEM) principle. The full dynamics of the sources is obtained from the inverse wavelet transform, and principal component analysis of the reconstructed time courses is applied to extract oscillatory components. This methodology is evaluated using realistic simulations of single-trial signals, combining fast and sudden discharges (spike) along with bursts of oscillating activity. The method is finally illustrated with a clinical application using MEG data acquired on a patient with a right orbitofrontal epilepsy.

  14. Writable electrochemical energy source based on graphene oxide

    Science.gov (United States)

    Wei, Di

    2015-10-01

    Graphene oxide (GO) was mainly used as raw material for various types of reduced graphene oxide (rGO) as a cost effective method to make graphene like materials. However, applications of its own unique properties such as extraordinary proton conductivity and super-permeability to water were overlooked. Here GO based battery-like planar energy source was demonstrated on arbitrary insulating substrate (e.g. polymer sheet/paper) by coating PEDOT, GO ink and rGO on Ag charge collectors. Energy from such GO battery depends on its length and one unit cell with length of 0.5 cm can generate energy capacity of 30 Ah/L with voltage up to 0.7 V when room temperature ionic liquid (RTIL) is added. With power density up to 0.4 W/cm3 and energy density of 4 Wh/L, GO battery was demonstrated to drive an electrochromic device. This work is the first attempt to generate decent energy using the fast transported water molecules inside GO. It provides very safe energy source that enables new applications otherwise traditional battery technology can not make including building a foldable energy source on paper and platform for futuristic wearable electronics. A disposable energy source made of GO was also written on a plastic glove to demonstrate wearability.

  15. A Parallax-based Distance Estimator for Spiral Arm Sources

    Science.gov (United States)

    Reid, M. J.; Dame, T. M.; Menten, K. M.; Brunthaler, A.

    2016-06-01

    The spiral arms of the Milky Way are being accurately located for the first time via trigonometric parallaxes of massive star-forming regions with the Bar and Spiral Structure Legacy Survey, using the Very Long Baseline Array and the European VLBI Network, and with the Japanese VLBI Exploration of Radio Astrometry project. Here we describe a computer program that leverages these results to significantly improve the accuracy and reliability of distance estimates to other sources that are known to follow spiral structure. Using a Bayesian approach, sources are assigned to arms based on their (l, b, v) coordinates with respect to arm signatures seen in CO and H i surveys. A source's kinematic distance, displacement from the plane, and proximity to individual parallax sources are also considered in generating a full distance probability density function. Using this program to estimate distances to large numbers of star-forming regions, we generate a realistic visualization of the Milky Way's spiral structure as seen from the northern hemisphere.

  16. Socio-Economic Status Affects Sentence Repetition, but Not Non-Word Repetition, in Chilean Preschoolers

    Science.gov (United States)

    Balladares, Jaime; Marshall, Chloë; Griffiths, Yvonne

    2016-01-01

    Sentence repetition and non-word repetition tests are widely used measures of language processing which are sensitive to language ability. Surprisingly little previous work has investigated whether children's socio-economic status (SES) affects their sentence and non-word repetition accuracy. This study investigates sentence and non-word…

  17. Waveguide-based OPO source of entangled photon pairs

    International Nuclear Information System (INIS)

    In this paper, we present a compact source of narrow-band energy-time-entangled photon pairs in the telecom regime based on a Ti-indiffused periodically poled lithium niobate (PPLN) waveguide resonator, i.e. a waveguide with end-face dielectric multi-layer mirrors. This is a monolithic doubly resonant optical parametric oscillator (OPO) far below threshold, which generates photon pairs by spontaneous parametric down-conversion (SPDC) at around 1560 nm with a 117 MHz (0.91 pm)-bandwidth. A coherence time of 2.7 ns is estimated by a time correlation measurement and a high quality of the entangled states is confirmed by a Bell-type experiment. Since highly coherent energy-time-entangled photon pairs in the telecom regime are suitable for long distance transmission and manipulation, this source is well suited to the requirements of quantum communication.

  18. Knowledge sources for evidence-based practice in rheumatology nursing.

    Science.gov (United States)

    Neher, Margit; Ståhl, Christian; Ellström, Per-Erik; Nilsen, Per

    2015-12-01

    As rheumatology nursing develops and extends, knowledge about current use of knowledge in rheumatology nursing practice may guide discussions about future knowledge needs. To explore what perceptions rheumatology nurses have about their knowledge sources and about what knowledge they use in their practice, 12 nurses working in specialist rheumatology were interviewed using a semi-structured interview guide. The data were analyzed using conventional qualitative content analysis. The analysis yielded four types of knowledge sources in clinical practice: interaction with others in the workplace, contacts outside the workplace, written materials, and previous knowledge and experience. Colleagues, and physicians in particular, were important for informal learning in daily rheumatology practice. Evidence from the medical arena was accessed through medical specialists, while nursing research was used less. Facilitating informal learning and continuing formal education is proposed as a way toward a more evidence-based practice in extended roles. PMID:25059719

  19. A Bright Single Photon Source Based on a Diamond Nanowire

    CERN Document Server

    Babinec, T; Khan, M; Zhang, Y; Maze, J; Hemmer, P R; Loncar, M

    2009-01-01

    The development of a robust light source that emits one photon at a time is an outstanding challenge in quantum science and technology. Here, at the transition from many to single photon optical communication systems, fully quantum mechanical effects may be utilized to achieve new capabilities, most notably perfectly secure communication via quantum cryptography. Practical implementations place stringent requirements on the device properties, including fast and stable photon generation, efficient collection of photons, and room temperature operation. Single photon light emitting devices based on fluorescent dye molecules, quantum dots, nanowires, and carbon nanotube material systems have all been explored, but none have simultaneously demonstrated all criteria. Here, we describe the design, fabrication, and characterization of a bright source of single photons consisting of an individual Nitrogen-vacancy color center (NV center) in a diamond nanowire operating in ambient conditions. The nanowire plays a posit...

  20. POKEHEAD: An Open Source Interactive Headphone Based HCI Platform

    DEFF Research Database (Denmark)

    Højlund, Marie; Trento, Stefano; Goudarzi, Visda;

    2012-01-01

    This paper introduces a novel interactive, human-computer interface and remote social communication system based on an augmented, hi-fidelity audio headphone platform. Specifically, this system- named Pokehead, currently utilizes the DUL embedded open-source accelerometer platform to gather 3-axis...... position data in order to trigger real-time sonic events via specified head gestures. These gestures are mapped to sound models that convey particular messages in order to control software on the mobile device or to another, simultaneous POKEHEAD user. The context for the project was motivated......, open source implementation. Our rapid prototype proved to be robust enough to work in performance for demonstration purposes and serves as a working proof of concept. In this paper we provide a technical description of our prototype, illustrate the context and motivation behind the project, and offer...

  1. GISCube, an Open Source Web-based GIS Application

    Science.gov (United States)

    Boustani, M.; Mattmann, C. A.; Ramirez, P.

    2014-12-01

    There are many Earth science projects and data systems being developed at the Jet Propulsion Laboratory, California Institute of Technology (JPL) that require the use of Geographic Information Systems (GIS). Three in particular are: (1) the JPL Airborne Snow Observatory (ASO) that measures the amount of water being generated from snow melt in mountains; (2) the Regional Climate Model Evaluation System (RCMES) that compares climate model outputs with remote sensing datasets in the context of model evaluation and the Intergovernmental Panel on Climate Change and for the U.S. National Climate Assessment and; (3) the JPL Snow Server that produces a snow and ice climatology for the Western US and Alaska, for the U.S. National Climate Assessment. Each of these three examples and all other earth science projects are strongly in need of having GIS and geoprocessing capabilities to process, visualize, manage and store GeoSpatial data. Beside some open source GIS libraries and some software like ArcGIS there are comparatively few open source, web-based and easy to use application that are capable of doing GIS processing and visualization. To address this, we present GISCube, an open source web-based GIS application that can store, visualize and process GIS and GeoSpatial data. GISCube is powered by Geothon, an open source python GIS cookbook. Geothon has a variety of Geoprocessing tools such data conversion, processing, spatial analysis and data management tools. GISCube has the capability of supporting a variety of well known GIS data formats in both vector and raster formats, and the system is being expanded to support NASA's and scientific data formats such as netCDF and HDF files. In this talk, we demonstrate how Earth science and other projects can benefit by using GISCube and Geothon, its current goals and our future work in the area.

  2. On volume-source representations based on the representation theorem

    Science.gov (United States)

    Ichihara, Mie; Kusakabe, Tetsuya; Kame, Nobuki; Kumagai, Hiroyuki

    2016-01-01

    We discuss different ways to characterize a moment tensor associated with an actual volume change of ΔV C , which has been represented in terms of either the stress glut or the corresponding stress-free volume change ΔV T . Eshelby's virtual operation provides a conceptual model relating ΔV C to ΔV T and the stress glut, where non-elastic processes such as phase transitions allow ΔV T to be introduced and subsequent elastic deformation of - ΔV T is assumed to produce the stress glut. While it is true that ΔV T correctly represents the moment tensor of an actual volume source with volume change ΔV C , an explanation as to why such an operation relating ΔV C to ΔV T exists has not previously been given. This study presents a comprehensive explanation of the relationship between ΔV C and ΔV T based on the representation theorem. The displacement field is represented using Green's function, which consists of two integrals over the source surface: one for displacement and the other for traction. Both integrals are necessary for representing volumetric sources, whereas the representation of seismic faults includes only the first term, as the second integral over the two adjacent fault surfaces, across which the traction balances, always vanishes. Therefore, in a seismological framework, the contribution from the second term should be included as an additional surface displacement. We show that the seismic moment tensor of a volume source is directly obtained from the actual state of the displacement and stress at the source without considering any virtual non-elastic operations. A purely mathematical procedure based on the representation theorem enables us to specify the additional imaginary displacement necessary for representing a volume source only by the displacement term, which links ΔV C to ΔV T . It also specifies the additional imaginary stress necessary for representing a moment tensor solely by the traction term, which gives the "stress glut." The

  3. Fourier domain mode-locked swept source at 1050 nm based on a tapered amplifier

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang;

    2010-01-01

    chromatic dispersion in standard optical fiber. We developed a novel light source with a tapered amplifier as gain medium, and investigated the FDML performance comparing two fiber delay lines with different dispersion properties. We introduced an additional gain element into the resonator, and thereby...... achieved stable FDML operation, exploiting the full bandwidth of the tapered amplifier despite high dispersion. The light source operates at a repetition rate of 116 kHz with an effective average output power in excess of 30 mW. With a total sweep range of 70 nm, we achieved an axial resolution of 15 μm...... in air (~11 μm in tissue) in OCT measurements. As our work shows, tapered amplifiers are suitable gain media for swept sources at 1050 nm with increased output power, while high gain counteracts dispersion effects in an FDML laser....

  4. Digital repetitive control under varying frequency conditions

    CERN Document Server

    Ramos, Germán A; Olm, Josep M

    2013-01-01

    The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area. Repetitive Control has proven to be an efficient way to face this topic. However, in some applications the frequency of the reference/disturbance signal is time-varying or uncertain. This causes an important performance degradation in the standard Repetitive Control scheme. This book presents some solutions to apply Repetitive Control in varying frequency conditions without loosing steady-state performance. It also includes a complete theoretical development and experimental results in two representative systems. The presented solutions are organized in two complementary branches: varying sampling period Repetitive Control and High Order Repetitive Control. The first approach allows dealing with large range frequency variations while the second allows dealing with small range frequency variations. The book also presents applications of the described techniques to a Roto-magnet plant and...

  5. Developing seismogenic source models based on geologic fault data

    Science.gov (United States)

    Haller, Kathleen M.; Basili, Roberto

    2011-01-01

    Calculating seismic hazard usually requires input that includes seismicity associated with known faults, historical earthquake catalogs, geodesy, and models of ground shaking. This paper will address the input generally derived from geologic studies that augment the short historical catalog to predict ground shaking at time scales of tens, hundreds, or thousands of years (e.g., SSHAC 1997). A seismogenic source model, terminology we adopt here for a fault source model, includes explicit three-dimensional faults deemed capable of generating ground motions of engineering significance within a specified time frame of interest. In tectonically active regions of the world, such as near plate boundaries, multiple seismic cycles span a few hundred to a few thousand years. In contrast, in less active regions hundreds of kilometers from the nearest plate boundary, seismic cycles generally are thousands to tens of thousands of years long. Therefore, one should include sources having both longer recurrence intervals and possibly older times of most recent rupture in less active regions of the world rather than restricting the model to include only Holocene faults (i.e., those with evidence of large-magnitude earthquakes in the past 11,500 years) as is the practice in tectonically active regions with high deformation rates. During the past 15 years, our institutions independently developed databases to characterize seismogenic sources based on geologic data at a national scale. Our goal here is to compare the content of these two publicly available seismogenic source models compiled for the primary purpose of supporting seismic hazard calculations by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the U.S. Geological Survey (USGS); hereinafter we refer to the two seismogenic source models as INGV and USGS, respectively. This comparison is timely because new initiatives are emerging to characterize seismogenic sources at the continental scale (e.g., SHARE in the

  6. Plasma-Based Studies on 4th Generation Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R W; Baldis, H A; Cauble, R C; Landen, O L; Wark, J S; Ng, A; Rose, S J; Lewis, C; Riley, D; Gauthier, J-C; Audebert, P

    2000-11-28

    The construction of a short pulse tunable x-ray laser source will be a watershed for plasma-based and warm dense matter research. The areas we will discuss below can be separated broadly into warn dense matter (WDM) research, laser probing of near solid density plasmas, and laser-plasma spectroscopy of ions in plasmas. The area of WDM refers to that part of the density-temperature phase space where the standard theories of condensed matter physics and/or plasma statistical physics are invalid. Warm dense matter, therefore, defines a region between solids and plasmas, a regime that is found in planetary interiors, cool dense stars, and in every plasma device where one starts from a solid, e.g., laser-solid matter produced plasma as well as all inertial fusion schemes. The study of dense plasmas has been severely hampered by the fact that laser-based methods have been unavailable. The single most useful diagnostic of local plasma conditions, e.g., the temperature (T{sub e}), the density (n{sub e}), and the ionization (Z), has been Thomson scattering. However, due to the fact that visible light will not propagate at electron densities, n{sub e}, {ge} 10{sup 22} cm{sup -3} implies dense plasmas can not be probed. The 4th generation sources, LCLS and Tesla will remove these restrictions. Laser-based plasma spectroscopic techniques have been used with great success to determine the line shapes of atomic transitions in plasmas, study the population kinetics of atomic systems embedded in plasmas, and look at redistribution of radiation. However. the possibilities end for plasmas with n{sub e} {ge} 10{sup 22} since light propagation through the medium is severely altered by the plasma. The entire field of high Z plasma kinetics from laser produced plasma will then be available to study with the tunable source.

  7. Open source based cadastral information system : ANCFCC-MOROCCO

    CERN Document Server

    Elasri, Hicham; Jamila, Aatab; Karima, Ganoun

    2012-01-01

    This present project is developing a geographic information system to support the cadastral business. This system based on open source solutions which developed within the National Agency of Land Registry, Cadastre and Cartography (ANCFCC) enabling monitoring and analysis of cadastral procedures as well as offering consumable services by other information systems: consultation and querying spatial data. The project will also assist the various user profiles in the completion of production tasks and the possibility to eliminate the deficiencies identified to ensure an optimum level of productivity

  8. Mapping methane emission sources over California based on airborne measurements

    Science.gov (United States)

    Karl, T.; Guha, A.; Peischl, J.; Misztal, P. K.; Jonsson, H.; Goldstein, A. H.; Ryerson, T. B.

    2011-12-01

    The California Global Warming Solutions Act of 2006 (AB 32) has created a need to accurately characterize the emission sources of various greenhouse gases (GHGs) and verify the existing state GHG inventory. Methane (CH4) is a major GHG with a global warming potential of 20 times that of CO2 and currently constitutes about 6% of the total statewide GHG emissions on a CO2 equivalent basis. Some of the major methane sources in the state are area sources where methane is biologically produced (e.g. dairies, landfills and waste treatment plants) making bottom-up estimation of emissions a complex process. Other potential sources include fugitive emissions from oil extraction processes and natural gas distribution network, emissions from which are not well-quantified. The lack of adequate field measurement data to verify the inventory and provide independently generated estimates further contributes to the overall uncertainty in the CH4 inventory. In order to gain a better perspective of spatial distribution of major CH4 sources in California, a real-time measurement instrument based on Cavity Ring Down Spectroscopy (CRDS) was installed in a Twin Otter aircraft for the CABERNET (California Airborne BVOC Emissions Research in Natural Ecosystems Transects) campaign, where the driving research goal was to understand the spatial distribution of biogenic VOC emissions. The campaign took place in June 2011 and encompassed over forty hours of airborne CH4 and CO2 measurements during eight unique flights which covered much of the Central Valley and its eastern edge, the Sacramento-San Joaquin delta and the coastal range. The coincident VOC measurements, obtained through a high frequency proton transfer reaction mass spectrometer (PTRMS), aid in CH4 source identification. High mixing ratios of CH4 (> 2000 ppb) are observed consistently in all the flight transects above the Central Valley. These high levels of CH4 are accompanied by high levels of methanol which is an important

  9. A gigawatt level repetitive rate adjustable magnetic pulse compressor.

    Science.gov (United States)

    Li, Song; Gao, Jing-Ming; Yang, Han-Wu; Qian, Bao-Liang; Li, Ze-Xin

    2015-08-01

    In this paper, a gigawatt level repetitive rate adjustable magnetic pulse compressor is investigated both numerically and experimentally. The device has advantages of high power level, high repetitive rate achievability, and long lifetime reliability. Importantly, dominate parameters including the saturation time, the peak voltage, and even the compression ratio can be potentially adjusted continuously and reliably, which significantly expands the applicable area of the device and generators based on it. Specifically, a two-stage adjustable magnetic pulse compressor, utilized for charging the pulse forming network of a high power pulse generator, is designed with different compression ratios of 25 and 18 through an optimized design process. Equivalent circuit analysis shows that the modification of compression ratio can be achieved by just changing the turn number of the winding. At the same time, increasing inductance of the grounded inductor will decrease the peak voltage and delay the charging process. Based on these analyses, an adjustable compressor was built and studied experimentally in both the single shot mode and repetitive rate mode. Pulses with peak voltage of 60 kV and energy per pulse of 360 J were obtained in the experiment. The rise times of the pulses were compressed from 25 μs to 1 μs and from 18 μs to 1 μs, respectively, at repetitive rate of 20 Hz with good repeatability. Experimental results show reasonable agreement with analyses. PMID:26329219

  10. A gigawatt level repetitive rate adjustable magnetic pulse compressor

    Science.gov (United States)

    Li, Song; Gao, Jing-Ming; Yang, Han-Wu; Qian, Bao-Liang; Li, Ze-Xin

    2015-08-01

    In this paper, a gigawatt level repetitive rate adjustable magnetic pulse compressor is investigated both numerically and experimentally. The device has advantages of high power level, high repetitive rate achievability, and long lifetime reliability. Importantly, dominate parameters including the saturation time, the peak voltage, and even the compression ratio can be potentially adjusted continuously and reliably, which significantly expands the applicable area of the device and generators based on it. Specifically, a two-stage adjustable magnetic pulse compressor, utilized for charging the pulse forming network of a high power pulse generator, is designed with different compression ratios of 25 and 18 through an optimized design process. Equivalent circuit analysis shows that the modification of compression ratio can be achieved by just changing the turn number of the winding. At the same time, increasing inductance of the grounded inductor will decrease the peak voltage and delay the charging process. Based on these analyses, an adjustable compressor was built and studied experimentally in both the single shot mode and repetitive rate mode. Pulses with peak voltage of 60 kV and energy per pulse of 360 J were obtained in the experiment. The rise times of the pulses were compressed from 25 μs to 1 μs and from 18 μs to 1 μs, respectively, at repetitive rate of 20 Hz with good repeatability. Experimental results show reasonable agreement with analyses.

  11. Strategies for Using Repetition as a Powerful Teaching Tool

    Science.gov (United States)

    Saville, Kirt

    2011-01-01

    Brain research indicates that repetition is of vital importance in the learning process. Repetition is an especially useful tool in the area of music education. The success of repetition can be enhanced by accurate and timely feedback. From "simple repetition" to "repetition with the addition or subtraction of degrees of freedom," there are many…

  12. Towards Evidence-Based Understanding of Electronic Data Sources

    DEFF Research Database (Denmark)

    Chen, Lianping; Ali Babar, Muhammad; Zhang, He

    2010-01-01

    Identifying relevant papers from various Electronic Data Sources (EDS) is one of the key activities of conducting these kinds of studies. Hence, the selection of EDS for searching the potentially relevant papers is an important decision, which can affect a study’s coverage of relevant papers....... Researchers usually select EDS mainly based on personal knowledge, experience, and preferences and/or recommendations by other researchers. We believe that building an evidence-based understanding of EDS can enable researchers to make more informed decisions about the selection of EDS. This paper reports our...... initial effort towards this end. We propose an initial set of metrics for characterizing the EDS from the perspective of the needs of secondary studies. We explain the usage and benefits of the proposed metrics using the data gathered from two secondary studies. We also tried to synthesize the data from...

  13. Continuous-wave optical fiber based supercontinuum light source

    Science.gov (United States)

    Lu, Z. G.; Song, Y.; Liu, J. R.; Zhang, X. P.

    2007-11-01

    We have demonstrated a continuum-wave (CW) supercontinuum (SC) fiber light source with over 1000 nm bandwidth based on a low-cost erbium/ytterbium co-doped double-cladding fiber ring cavity laser. Based on the observation to the SC evolvement, we have experimentally analyzed the detailed contributions of several nonlinear effects within highly nonlinear dispersion-shifted fiber (HNLF). Our experimental results have clearly indicated that four-wave mixing (FWM) and stimulated Raman scattering (SRS) play key roles in CW-pumped SC generation. At the same time, self-phase modulation (SPM) mainly contributes to generate new frequency components near the peaks that appear in the form of the spectra broadening while cross-phase modulation (XPM) enhances the broadening of peaks.

  14. Narrow-Bandwidth Diode-Laser-Based Ultraviolet Light Source

    Institute of Scientific and Technical Information of China (English)

    PENG Yu; FANG Zhan-Jun; ZANG Er-Jun

    2011-01-01

    A compact, tunable and narrow-bandwidth laser source for ultraviolet radiation is presented. A grating stabilized diode laser at 1064 nm is frequency-stabilized to below 10 kHz by using a ultra low expansion (ULE) cavity. Injecting light of the diode laser into a tapered amplifier yields a power of 290mW. In a first frequency-doubling stage, about 47 mW of green light at 532nm is generated by using a periodical// poled KTP crystal. Subsequent second-harwonic generation employing a BBO crystal leads to about 30μW of ultraviolet light at 266nm.%A compact,tunable and narrow-bandwidth laser source for ultraviolet radiation is presented.A grating stabilized diode laser at 1064nm is frequency-stabilized to below 10kHz by using a ultra low expansion (ULE) cavity.Injecting light of the diode laser into a tapered amplifier yields a power of 290 mW.In a first frequency-doubling stage,about 47mW of green light at 532nm is generated by using a periodically poled KTP crystal.Subsequent second-harmonic generation employing a BBO crystal leads to about 30 μ W of ultraviolet light at 266nm.Hg is,so far,the heaviest nonradioactive atom that has been laser-cooled and trapped.Systematic evaluation of various sources of uncertainty for the Hg-based optical lattice clock is obtained and an accuracy of better than 10-1s is attainable,which is an order of magnitude of improvement over Sr or Yb based clocks because of the reduced susceptibility to the blackbody radiation field,which sets a major limitation on the accuracy of atomic clocks.[1] The 1S0-3p0 transition at 265.6 nm will be exploited as a clock transition.

  15. Cardiac magnetic source imaging based on current multipole model

    Institute of Scientific and Technical Information of China (English)

    Tang Fa-Kuan; Wang Qian; Hua Ning; Lu Hong; Tang Xue-Zheng; Ma Ping

    2011-01-01

    It is widely accepted that the heart current source can be reduced into a current multipole. By adopting three linear inverse methods, the cardiac magnetic imaging is achieved in this article based on the current multipole model expanded to the first order terms. This magnetic imaging is realized in a reconstruction plane in the centre of human heart, where the current dipole array is employed to represent realistic cardiac current distribution. The current multipole as testing source generates magnetic fields in the measuring plane, serving as inputs of cardiac magnetic inverse problem. In the heart-torso model constructed by boundary element method, the current multipole magnetic field distribution is compared with that in the homogeneous infinite space, and also with the single current dipole magnetic field distribution.Then the minimum-norm least-squares (MNLS) method, the optimal weighted pseuDOInverse method (OWPIM), and the optimal constrained linear inverse method (OCLIM) are selected as the algorithms for inverse computation based on current multipole model innovatively, and the imaging effects of these three inverse methods are compared. Besides,two reconstructing parameters, residual and mean residual, are also discussed, and their trends under MNLS, OWPIM and OCLIM each as a function of SNR are obtained and compared.

  16. A refined, rapid and reproducible high resolution melt (HRM-based method suitable for quantification of global LINE-1 repetitive element methylation

    Directory of Open Access Journals (Sweden)

    Tse M Yat

    2011-12-01

    Full Text Available Abstract Background The methylation of DNA is recognized as a key mechanism in the regulation of genomic stability and evidence for its role in the development of cancer is accumulating. LINE-1 methylation status represents a surrogate measure of genome-wide methylation. Findings Using high resolution melt (HRM curve analysis technology, we have established an in-tube assay that is linear (r > 0.9986 with a high amplification efficiency (90-105%, capable of discriminating between partcipant samples with small differences in methylation, and suitable for quantifying a wide range of LINE-1 methylation levels (0-100%--including the biologically relevant range of 50-90% expected in human DNA. We have optimized this procedure to perform using 2 μg of starting DNA and 2 ng of bisulfite-converted DNA for each PCR reaction. Intra- and inter-assay coefficients of variation were 1.44% and 0.49%, respectively, supporting the high reproducibility and precision of this approach. Conclusions In summary, this is a completely linear, quantitative HRM PCR method developed for the measurement of LINE-1 methylation. This cost-efficient, refined and reproducible assay can be performed using minimal amounts of starting DNA. These features make our assay suitable for high throughput analysis of multiple samples from large population-based studies.

  17. “Water window” compact, table-top laser plasma soft X-ray sources based on a gas puff target

    Science.gov (United States)

    Wachulak, P. W.; Bartnik, A.; Fiedorowicz, H.; Rudawski, P.; Jarocki, R.; Kostecki, J.; Szczurek, M.

    2010-05-01

    We have developed compact, high repetition, table-top soft-X-ray sources, based on a gas puff target, emitting in "water window" spectral range at λ = 2.88 nm from nitrogen gas target or, in 2-4 nm range of wavelengths, from argon gas target. Double stream gas puff target was pumped optically by commercial Nd:YAG laser, energy 0.74 J, pulse time duration 4 ns. Spatial distribution of laser-produced plasma was imaged using a pinhole camera. Using transmission grating spectrometer, argon and nitrogen emission spectra were obtained, showing strong emission in the "water window" spectral range. Using AXUV100 detector the flux measurements of the soft-X-ray pulses were carried out and are presented. These debris free sources are table-top alternative for free electron lasers and synchrotron installations. They can be successfully employed in microscopy, spectroscopy and metrology experiments among others.

  18. Future Synchrotron Light Sources Based on Ultimate Storage Rings

    International Nuclear Information System (INIS)

    The main purpose of this talk is to describe how far one might push the state of the art in storage ring design. The talk will start with an overview of the latest developments and advances in the design of synchrotron light sources based on the concept of an 'ultimate' storage ring. The review will establish how bright a ring based light source might be, where the frontier of technological challenges are, and what the limits of accelerator physics are. Emphasis will be given to possible improvements in accelerator design and developments in technology toward the goal of achieving an ultimate storage ring. An ultimate storage ring (USR), defined as an electron ring-based light source having an emittance in both transverse planes at the diffraction limit for the range of X-ray wavelengths of interest for a scientific community, would provide very high brightness photons having high transverse coherence that would extend the capabilities of X-ray imaging and probe techniques beyond today's performance. It would be a cost-effective, high-coherence 4th generation light source, competitive with one based on energy recovery linac (ERL) technology, serving a large number of users studying material, chemical, and biological sciences. Furthermore, because of the experience accumulated over many decades of ring operation, it would have the great advantage of stability and reliability. In this paper we consider the design of an USR having 10-pm-rad emittance. It is a tremendous challenge to design a storage ring having such an extremely low emittance, a factor of 100 smaller than those in existing light sources, especially such that it has adequate dynamic aperture and beam lifetime. In many ultra-low emittance designs, the injection acceptances are not large enough for accumulation of the electron beam, necessitating on-axis injection where stored electron bunches are completely replaced with newly injected ones. Recently, starting with the MAX-IV 7-bend achromatic cell, we

  19. Self-compression to 24 MW peak power in a fused silica solid-core fiber using a high-repetition rate thulium-based fiber laser system

    Science.gov (United States)

    Gebhardt, Martin; Gaida, Christian; Stutzki, Fabian; Hädrich, Steffen; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2016-03-01

    Complementing ultrafast thulium-doped fiber-laser systems with a subsequent nonlinear pulse compression stage can enable unique laser parameters at around 2 μm operation wavelength. Significant pulse shortening and peak power enhancement have been accomplished using a fused silica solid-core fiber. In this fiber a pulse peak power of 24 MW was achieved without catastrophic damage due to self-focusing. As compared to operation in the well-explored 1 μm wavelength region, increasing the emission wavelength to 2 μm has a twofold advantage for nonlinear compression in fused-silica solid-core fibers. This is because, on the one hand the self-focusing limit scales quadratically with the wavelength. On the other hand the dispersion properties of fused silica allow for self-compression of ultrashort pulses beyond 1.3 μm wavelength, which leads to strong spectral broadening from very compact setups without the need for external compression. Using this technique we have generated 1.1 μJpulses with 24 fs FWHM pulse duration (power and 24.6 W of average power. To the best of our knowledge, this is the highest average power obtained from any nonlinear compression experiment around 2 μm wavelength and the first demonstration of peak powers beyond 20 MW within a fused-silica solid-core fiber. This result emphasizes that thulium-doped fiber-based chirped-pulse amplification systems may outperform their ytterbiumdoped counterparts in terms of peak power due to the fourfold increase of the critical power of self-focusing.

  20. Virtual point source efficiency calibration method for voluminous sample of radio-xenon based on efficiency function of point source

    International Nuclear Information System (INIS)

    A virtual point source calibration method is developed to finish the calibration of voluminous sample. We used a mixed point source to get the parameters of efficiency function, obtaining the virtual position of voluminous sample. So, the detection efficiency of xenon samples and standard soil samples were calibrated by placing the point source at their virtual position. The Monte Carlo method was also used to simulate the detector efficiency of xenon samples. Deviations between the virtual source method and Monte Carlo simulation are within 2.2 % for xenon samples. Thus, we have developed two robust efficiency calibration methods based on Monte Carlo simulations and virtual point source, respectively. (author)

  1. Hemispheric Asymmetries in Repetition Enhancement and Suppression Effects in the Newborn Brain.

    Directory of Open Access Journals (Sweden)

    Camillia Bouchon

    Full Text Available The repeated presentation of stimuli typically attenuates neural responses (repetition suppression or, less commonly, increases them (repetition enhancement when stimuli are highly complex, degraded or presented under noisy conditions. In adult functional neuroimaging research, these repetition effects are considered as neural correlates of habituation. The development and respective functional significance of these effects in infancy remain largely unknown.This study investigates repetition effects in newborns using functional near-infrared spectroscopy, and specifically the role of stimulus complexity in evoking a repetition enhancement vs. a repetition suppression response, following up on Gervain et al. (2008. In that study, abstract rule-learning was found at birth in cortical areas specific to speech processing, as evidenced by a left-lateralized repetition enhancement of the hemodynamic response to highly variable speech sequences conforming to a repetition-based ABB artificial grammar, but not to a random ABC grammar.Here, the same paradigm was used to investigate how simpler stimuli (12 different sequences per condition as opposed to 140, and simpler presentation conditions (blocked rather than interleaved would influence repetition effects at birth.Results revealed that the two grammars elicited different dynamics in the two hemispheres. In left fronto-temporal areas, we reproduce the early perceptual discrimination of the two grammars, with ABB giving rise to a greater response at the beginning of the experiment than ABC. In addition, the ABC grammar evoked a repetition enhancement effect over time, whereas a stable response was found for the ABB grammar. Right fronto-temporal areas showed neither initial discrimination, nor change over time to either pattern.Taken together with Gervain et al. (2008, this is the first evidence that manipulating methodological factors influences the presence or absence of neural repetition enhancement

  2. A Study on Repetition Techniques in Persian Morphology

    Directory of Open Access Journals (Sweden)

    a Vafaie

    2011-06-01

    Full Text Available The speakers of any language, according to their constant need, coin some novel words in order to convey meaning, express ideas, thoughts, and their desires. In this process, they take advantage of their overt or covert linguistic competence. For instance, the derivative feature of Arabic language has contributed a lot to speakers of that language to create so many words with multiple meanings, all formed on the same stem. Likewise, English speakers make use of the derivative features, compounding, blending, and multiple processes of their language to create words. Similarly, in Persian language, the speakers make new words based on specific features of that language. There are five common processes applied in Persian language to form new words, among which blending, compounding, derivation, repetition or reduplication, clipping and acronyms are frequently used and the other techniques or processes have been neglected. Word repetition is one of the word formation processes and many words are made through this process. This study is an attempt to delve into the morphological processes of word repetition in Persian contemporary language according to the texts of three books, “Imaginary Perspectives in Persian Poetry”, “Let’s Listen to the Speech” and “with Holleh Convoy”. In addition, it strives to find a proper solution to the question of the Persian word formation processes in creating new words through repetition.

  3. Practicing novel, praxis-like movements: physiological effects of repetition

    Directory of Open Access Journals (Sweden)

    Joshua Benjamin Ewen

    2016-02-01

    Full Text Available Our primary goal was to develop and validate a task that could provide evidence about how humans learn praxis gestures, such as those involving the use of tools. To that end, we created a video-based task in which subjects view a model performing novel, meaningless one-handed actions with kinematics similar to praxis gestures. Subjects then imitated the movements with their right hand. Trials were repeated 6 times to examine practice effects. EEG was recorded during the task. As a control, subjects watched videos of a model performing a well-established (over learned tool-use gesture. These gestures were also imitated 6 times. Demonstrating convergent validity, EEG measures of task-related cortical activation were similar in topography and frequency between the novel gesture task and the overlearned, praxis gesture task. As in studies assessing motor skill learning with simpler tasks, cortical activation during novel gesture learning decreased as the same gestures were repeated. In the control condition, repetition of overlearned tool-use gestures were also associated with reductions in activation, though to a lesser degree. Given that even overlearned, praxis gestures show constriction of EEG activity with repetition, it is possible that that attentional effects drive some of the repetition effects seen in EEG measures of activation during novel gesture repetition.

  4. Practicing Novel, Praxis-Like Movements: Physiological Effects of Repetition.

    Science.gov (United States)

    Ewen, Joshua B; Pillai, Ajay S; McAuliffe, Danielle; Lakshmanan, Balaji M; Ament, Katarina; Hallett, Mark; Crone, Nathan E; Mostofsky, Stewart H

    2016-01-01

    Our primary goal was to develop and validate a task that could provide evidence about how humans learn praxis gestures, such as those involving the use of tools. To that end, we created a video-based task in which subjects view a model performing novel, meaningless one-handed actions with kinematics similar to praxis gestures. Subjects then imitated the movements with their right hand. Trials were repeated six times to examine practice effects. EEG was recorded during the task. As a control, subjects watched videos of a model performing a well-established (over learned) tool-use gesture. These gestures were also imitated six times. Demonstrating convergent validity, EEG measures of task-related cortical activation were similar in topography and frequency between the novel gesture task and the overlearned, praxis gesture task. As in studies assessing motor skill learning with simpler tasks, cortical activation during novel gesture learning decreased as the same gestures were repeated. In the control condition, repetition of overlearned tool-use gestures were also associated with reductions in activation, though to a lesser degree. Given that even overlearned, praxis gestures show constriction of EEG activity with repetition, it is possible that that attentional effects drive some of the repetition effects seen in EEG measures of activation during novel gesture repetition. PMID:26903835

  5. Practicing Novel, Praxis-Like Movements: Physiological Effects of Repetition

    Science.gov (United States)

    Ewen, Joshua B.; Pillai, Ajay S.; McAuliffe, Danielle; Lakshmanan, Balaji M.; Ament, Katarina; Hallett, Mark; Crone, Nathan E.; Mostofsky, Stewart H.

    2016-01-01

    Our primary goal was to develop and validate a task that could provide evidence about how humans learn praxis gestures, such as those involving the use of tools. To that end, we created a video-based task in which subjects view a model performing novel, meaningless one-handed actions with kinematics similar to praxis gestures. Subjects then imitated the movements with their right hand. Trials were repeated six times to examine practice effects. EEG was recorded during the task. As a control, subjects watched videos of a model performing a well-established (over learned) tool-use gesture. These gestures were also imitated six times. Demonstrating convergent validity, EEG measures of task-related cortical activation were similar in topography and frequency between the novel gesture task and the overlearned, praxis gesture task. As in studies assessing motor skill learning with simpler tasks, cortical activation during novel gesture learning decreased as the same gestures were repeated. In the control condition, repetition of overlearned tool-use gestures were also associated with reductions in activation, though to a lesser degree. Given that even overlearned, praxis gestures show constriction of EEG activity with repetition, it is possible that that attentional effects drive some of the repetition effects seen in EEG measures of activation during novel gesture repetition. PMID:26903835

  6. Acoustic emission source localization based on distance domain signal representation

    Science.gov (United States)

    Gawronski, M.; Grabowski, K.; Russek, P.; Staszewski, W. J.; Uhl, T.; Packo, P.

    2016-04-01

    Acoustic emission is a vital non-destructive testing technique and is widely used in industry for damage detection, localisation and characterization. The latter two aspects are particularly challenging, as AE data are typically noisy. What is more, elastic waves generated by an AE event, propagate through a structural path and are significantly distorted. This effect is particularly prominent for thin elastic plates. In these media the dispersion phenomenon results in severe localisation and characterization issues. Traditional Time Difference of Arrival methods for localisation techniques typically fail when signals are highly dispersive. Hence, algorithms capable of dispersion compensation are sought. This paper presents a method based on the Time - Distance Domain Transform for an accurate AE event localisation. The source localisation is found through a minimization problem. The proposed technique focuses on transforming the time signal to the distance domain response, which would be recorded at the source. Only, basic elastic material properties and plate thickness are used in the approach, avoiding arbitrary parameters tuning.

  7. Detection of Oil Pollution Hotspots and Leak Sources Through the Quantitative Assessment of the Persistence and Temporal Repetition of Regular Oil Spills in the Caspian Sea Using Remote Sensing and GIS

    Science.gov (United States)

    Bayramov, E. R.; Buchroithner, M. F.; Bayramov, R. V.

    2015-08-01

    The main goal of this research was to detect oil spills, to determine the oil spill frequencies and to approximate oil leak sources around the Oil Rocks Settlement, the Chilov and Pirallahi Islands in the Caspian Sea using 136 multi-temporal ENVISAT Advanced Synthetic Aperture Radar Wide Swath Medium Resolution Images acquired during 2006-2010. The following oil spill frequencies were observed around the Oil Rocks Settlement, the Chilov and Pirallahi Islands: 2-10 (3471.04 sq. km.), 11-20 (971.66 sq. km.), 21-50 (692.44 sq. km.), 51-128 (191.38 sq. km.). The most critical oil leak sources with the frequency range of 41-128 were observed at the Oil Rocks Settlement. The exponential regression analysis between wind speeds and oil slick areas detected from 136 multi-temporal ENVISAT images revealed the regression coefficient equal to 63%. The regression model showed that larger oil spill areas were observed with decreasing wind speeds. The spatiotemporal patterns of currents in the Caspian Sea explained the multi-directional spatial distribution of oil spills around Oil Rocks Settlement, the Chilov and Pirallahi Islands. The linear regression analysis between detected oil spill frequencies and predicted oil contamination probability by the stochastic model showed the positive trend with the regression coefficient of 30%.

  8. Monolithic fuel cell based power source for burst power generation

    Science.gov (United States)

    Fee, D. C.; Blackburn, P. E.; Busch, D. E.; Dees, D. W.; Dusek, J.; Easler, T. E.; Ellingson, W. A.; Flandermeyer, B. K.; Fousek, R. J.; Heiberger, J. J.

    A unique fuel cell coupled with a low power nuclear reactor presents an attractive approach for SDI burst power requirements. The monolithic fuel cell looks attractive for space applications and represents a quantum jump in fuel cell technology. Such a breakthrough in design is the enabling technology for lightweight, low volume power sources for space based pulse power systems. The monolith is unique among fuel cells in being an all solid state device. The capability for miniaturization, inherent in solid state devices, gives the low volume required for space missions. In addition, the solid oxide fuel cell technology employed in the monolith has high temperature reject heat and can be operated in either closed or open cycles. Both these features are attractive for integration into a burst power system.

  9. Semidefinite programming approach for TDOA/GROA based source localization

    Institute of Scientific and Technical Information of China (English)

    Yanshen Du; Ping Wei; Huaguo Zhang

    2015-01-01

    Time-differences-of-arrival (TDOA) and gain-ratios-of-arrival (GROA) measurements are used to determine the passive source location. Based on the measurement models, the con-strained weighted least squares (CWLS) estimator is presented. Due to the nonconvex nature of the CWLS problem, it is difficult to obtain its global y optimal solution. However, according to the semidefinite relaxation, the CWLS problem can be relaxed as a convex semidefinite programming problem (SDP), which can be solved by using modern convex optimization algorithms. Moreover, this relaxation can be proved to be tight, i.e., the SDP solves the relaxed CWLS problem, and this hence guarantees the good per-formance of the proposed method. Furthermore, this method is extended to solve the localization problem with sensor position errors. Simulation results corroborate the theoretical results and the good performance of the proposed method.

  10. Current Source Converter Based Wind Energy Conversion Systems

    Institute of Scientific and Technical Information of China (English)

    Samir Kouro; Jing-ya DAI; Bin WU

    2011-01-01

    The increase in the installed capacity of wind energy conversion systems (WECS) has triggered the development of more demanding grid codes and additional requirements on performance.In order to meet these requirements the industry trend has shifted to full-scale power converter interfaces in modern multi-megawatt WECS.As consequence,a wide variety of new power converter topologies and WECS configurations have been introduced in recent years.Among them,current source converter(CSC) based configurations have attracted attention due to a series of advantages like:simple structure,grid friendly waveforms,controllable power factor,and reliable grid short-circuit protection.This paper presents the latest developments in CSC interfaces for WECS and related technologies such as modulation methods,control schemes and grid code compatibility.

  11. Cloud based, Open Source Software Application for Mitigating Herbicide Drift

    Science.gov (United States)

    Saraswat, D.; Scott, B.

    2014-12-01

    The spread of herbicide resistant weeds has resulted in the need for clearly marked fields. In response to this need, the University of Arkansas Cooperative Extension Service launched a program named Flag the Technology in 2011. This program uses color-coded flags as a visual alert of the herbicide trait technology within a farm field. The flag based program also serves to help avoid herbicide misapplication and prevent herbicide drift damage between fields with differing crop technologies. This program has been endorsed by Southern Weed Science Society of America and is attracting interest from across the USA, Canada, and Australia. However, flags have risk of misplacement or disappearance due to mischief or severe windstorms/thunderstorms, respectively. This presentation will discuss the design and development of a cloud-based, free application utilizing open-source technologies, called Flag the Technology Cloud (FTTCloud), for allowing agricultural stakeholders to color code their farm fields for indicating herbicide resistant technologies. The developed software utilizes modern web development practices, widely used design technologies, and basic geographic information system (GIS) based interactive interfaces for representing, color-coding, searching, and visualizing fields. This program has also been made compatible for a wider usability on different size devices- smartphones, tablets, desktops and laptops.

  12. Developmental Norms for the Sentence Repetition Test.

    Science.gov (United States)

    Carmichael, John A.; MacDonald, John W.

    1984-01-01

    Obtained developmental norms for the Sentence Repetition Test from children (N=1,081) ranging in age from three to 13 years. Utilized a substanially larger number of children in each age group than previous reports. (Author/LLL)

  13. Development of a mobile device optimized cross platform-compatible oral pathology and radiology spaced repetition system for dental education.

    Science.gov (United States)

    Al-Rawi, Wisam; Easterling, Lauren; Edwards, Paul C

    2015-04-01

    Combining active recall testing with spaced repetition increases memory retention. The aim of this study was to evaluate and compare students' perception and utilization of an electronic spaced repetition oral pathology-radiology system in dental hygiene education and predoctoral dental education. The study employed an open-source suite of applications to create electronic "flashcards" that can be individually adjusted for frequency of repetition, depending on a user's assessment of difficulty. Accessible across multiple platforms (iOS, Android, Linux, OSX, Windows) as well as via any web-based browser, this framework was used to develop an oral radiology-oral pathology database of case-based questions. This system was introduced in two courses: sophomore oral pathology for dental students and sophomore radiology for dental hygiene students. Students were provided free software and/or mobile tablet devices as well as a database of 300 electronic question cards. Study participants were surveyed on frequency and extent of use. Perception-based surveys were used to evaluate their attitudes towards this technology. Of the eligible students, 12 of 22 (54.5%) dental hygiene and 49 of 107 (45.8%) dental students responded to the surveys. Adoption rates and student feedback were compared between the two groups. Among the respondents, acceptance of this technology with respect to educational usefulness was similar for the dental and dental hygiene students (median=5 on a five-point scale; dental hygiene interquartile range (IQR)=0; dental IQR=1). Only a minority of the survey respondents (25% dental, 33% dental hygiene) took advantage of one of the main benefits of this technology: automated spaced repetition. PMID:25838016

  14. Repetitive Sequences in Plant Nuclear DNA:Types, Distribution, Evolution and Function

    Institute of Scientific and Technical Information of China (English)

    Shweta Mehrotra; Vinod Goyal

    2014-01-01

    Repetitive DNA sequences are a major component of eukaryotic genomes and may account for up to 90% of the genome size. They can be divided into minisatellite, microsatellite and satellite sequences. Satellite DNA sequences are considered to be a fast-evolving component of eukaryotic genomes, comprising tandemly-arrayed, highly-repetitive and highly-conserved monomer sequences. The monomer unit of satellite DNA is 150-400 base pairs (bp) in length. Repetitive sequences may be species- or genus-specific, and may be centromeric or subtelomeric in nature. They exhibit cohesive and concerted evolution caused by molecular drive, leading to high sequence homogeneity. Repetitive sequences accumulate variations in sequence and copy number during evolution, hence they are important tools for taxonomic and phylogenetic studies, and are known as‘‘tuning knobs’’ in the evolution. Therefore, knowledge of repetitive sequences assists our understanding of the organization, evolution and behavior of eukaryotic genomes. Repetitive sequences have cytoplasmic, cellular and developmental effects and play a role in chromosomal recombination. In the post-genomics era, with the introduction of next-generation sequencing tech-nology, it is possible to evaluate complex genomes for analyzing repetitive sequences and decipher-ing the yet unknown functional potential of repetitive sequences.

  15. Finite-Repetition threshold for infinite ternary words

    Directory of Open Access Journals (Sweden)

    Golnaz Badkobeh

    2011-08-01

    Full Text Available The exponent of a word is the ratio of its length over its smallest period. The repetitive threshold r(a of an a-letter alphabet is the smallest rational number for which there exists an infinite word whose finite factors have exponent at most r(a. This notion was introduced in 1972 by Dejean who gave the exact values of r(a for every alphabet size a as it has been eventually proved in 2009. The finite-repetition threshold for an a-letter alphabet refines the above notion. It is the smallest rational number FRt(a for which there exists an infinite word whose finite factors have exponent at most FRt(a and that contains a finite number of factors with exponent r(a. It is known from Shallit (2008 that FRt(2=7/3. With each finite-repetition threshold is associated the smallest number of r(a-exponent factors that can be found in the corresponding infinite word. It has been proved by Badkobeh and Crochemore (2010 that this number is 12 for infinite binary words whose maximal exponent is 7/3. We show that FRt(3=r(3=7/4 and that the bound is achieved with an infinite word containing only two 7/4-exponent words, the smallest number. Based on deep experiments we conjecture that FRt(4=r(4=7/5. The question remains open for alphabets with more than four letters. Keywords: combinatorics on words, repetition, repeat, word powers, word exponent, repetition threshold, pattern avoidability, word morphisms.

  16. Characterization of Chenopodium quinoa chromosomes using fish and repetitive sequences

    International Nuclear Information System (INIS)

    Quinoa is one of the underestimated crops, which recently attracted attention. During last few years many efforts were done to save the natural genetic diversity of quinoa cultivars and landraces as well as to obtained new variability by mutagenesis. Plant characteristics based mainly on morphological and molecular markers. Cytogenetic analysis was not used for these studies. Quinoa is an allotetraploid species with 36 small chromosomes. To follow the chromosomal rearrangement cause by spontaneous or induced mutations it is necessary to find cytogenetics markers for chromosomes and chromosome arms. The physical mapping of repetitive DNAs by fluorescent in situ hybridization (FISH) can provide a valuable tool in studies of genome organization and chromosome rearrangements. To characterized quinoa genome several repetitive sequences were used as DNA probes for FISH. Double FISH with rRNA genes as probes allowed to distinguished three pairs of homologue chromosomes. Telomeric repeats hybridisation signals were present only in terminal part of all chromosome arms and no intercalar position was observed. Other tandem repetitive sequence - minisatellite was characteristic for centromeric and pericentromeric region of all quinoa chromosomes although number of repeats differ between loci. It allowed to divided quinoa chromosomes into few groups. Disperse repetitive sequences such as mobile element-like sequences used in this study were detected in all eighteen chromosome pairs. Hybridization signals were characteristics for pericentromeric region of one or both chromosome arms as relatively weak but discrete signals although few chromosomes exhibited signals in intercalary position. Two others repetitive sequences also exhibited disperse organization; however they are not mobile elements. Their FISH signals were spread throughout whole chromosome arms but only one was present on all quinoa chromosomes. The other revealed hybridization signals only on the half of the

  17. Bit-Based Joint Source-Channel Decoding of Huffman Encoded Markov Multiple Sources

    Directory of Open Access Journals (Sweden)

    Weiwei Xiang

    2010-04-01

    Full Text Available Multimedia transmission over time-varying channels such as wireless channels has recently motivated the research on the joint source-channel technique. In this paper, we present a method for joint source-channel soft decision decoding of Huffman encoded multiple sources. By exploiting the a priori bit probabilities in multiple sources, the decoding performance is greatly improved. Compared with the single source decoding scheme addressed by Marion Jeanne, the proposed technique is more practical in wideband wireless communications. Simulation results show our new method obtains substantial improvements with a minor increasing of complexity. For two sources, the gain in SNR is around 1.5dB by using convolutional codes when symbol-error rate (SER reaches 10-2 and around 2dB by using Turbo codes.

  18. Fission, spallation or fusion-based neutron sources

    Indian Academy of Sciences (India)

    Kurt N Clausen

    2008-10-01

    In this paper the most promising technology for high power neutron sources is briefly discussed. The conclusion is that the route to high power neutron sources in the foreseeable future is spallation – short or long pulse or even CW – all of these sources will have areas in which they excel.

  19. Sources

    OpenAIRE

    2015-01-01

    Sources Fondation Pablo Iglesias. Alcala de Henares. Sections : Archives privées de Manuel ArijaArchives extérieuresArchives FNJS de EspañaPrensa Archives Générales de l’Administration. Alcala de Henares. Sections : Opposition au franquismeSig. 653 Sig TOP 82/68.103-68.602.Índice de las cartas colectivas, Relaciones, Cartas al Ministro de Información de Marzo de 1965. c.662. Sources cinématographiques Filmothèque Nationale d’Espagne.NO.DO. N° 1157C. 08/03/1965.aguirre Javier, Blanco vertical....

  20. An ion source based on the cathodic arc

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, D.M.; Falabella, S.

    1992-12-31

    This invention is comprised of a cylindrically symmetric arc source to produce a ring of ions which leave the surface of the arc target radially and are reflected by electrostatic fields present in the source to a point of use, such as a part to be coated. An array of electrically isolated rings positioned in the source serves the duel purpose of minimizing bouncing of macroparticles and providing electrical insulation to maximize the electric field gradients within the source. The source also includes a series of baffles which function as a filtering or trapping mechanism for any macroparticles.

  1. Arrangement of repetitive sequences in the genome of herpesvirus Sylvilagus.

    OpenAIRE

    Medveczky, M M; Geck, P; Clarke, C; Byrnes, J; Sullivan, J L; Medveczky, P G

    1989-01-01

    Herpesvirus sylvilagus is a lymphotropic (type gamma) herpesvirus of cottontail rabbits (Sylvilagus floridanus). Analysis of virion DNA of herpesvirus sylvilagus has revealed that the genome consists of one stretch of about 120 kilobase pairs of internal, unique DNA flanked by a variable number of 553-base-pair tandem repeats. The G + C content of the repetitive DNA is extremely high (83%), as determined by sequencing. The organization of the herpesvirus sylvilagus genome is, therefore, simil...

  2. Repetitions of fundamental research models for homeopathically prepared dilutions beyond 10-23: a bibliometric study

    Directory of Open Access Journals (Sweden)

    Peter Christian Endler

    2011-07-01

    Full Text Available Introduction: Repeatability of experiments is an important criterion of modern research and a major challenge for homeopathic basic research. There is a lack of a recent overview about basic research studies in high homeopathic potencies that have been subjected to laboratory-internal, multicenter or independent repetition trials. Methods: We considered biochemical, immunological, botanical, cell biological and zoological studies on high potencies, i.e. beyond a dilution of 10-23. Main sources of information were reviews, personal contact with members of the homeopathic basic research community, and the MEDLINE and HOMBREX databases. Studies were extracted from the publications and grouped into models. Studies were further sorted according to repetition type (laboratory-internal, multicenter, or independent and results achieved. Results: A total of 107 studies have been found. From these, 30 were initial studies. In the attempt to reproduce one of these initial studies, 53 follow up studies yielded comparable effects (35 laboratory-internal, 8 multicenter, 10 independent repetitions, eight studies showed a consistent, yet different result from the initial study (2 laboratory-internal, 2 multicenter, 4 independent repetitions, and 16 studies yielded zero effects (5 laboratory-internal, 2 multicenter, 9 independent repetitions. When all repetitive studies are considered, 69% reported effects comparable to that of the initial study, 10% different effects, and 21% zero effects. Independently performed repetition studies reported 44% comparable effects, 17% different effects, and 39% zero effects. Conclusions: We identified 24 experimental models in basic research on high homeopathic potencies, which were repeatedly investigated. 22 models were reproduced with comparable results, 6 models with different results, and repetition showed no results for 15 models. Independent reproductions with either comparable or different results were found for seven

  3. Tip-based electron source for femtosecond electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Stein, Jan-Paul; Hoffrogge, Johannes; Schenk, Markus; Krueger, Michael; Baum, Peter; Hommelhoff, Peter [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching bei Muenchen (Germany)

    2012-07-01

    Illumination of a sharp tungsten tip with femtosecond laser pulses leads to the emission of ultrashort, high brightness electron pulses that are ideally suited for ultrafast electron diffraction (UED) experiments [1]. The tip's small virtual source size ({proportional_to}5 nm) results in a large transverse coherence length of the electron pulse and therefore better spatial resolution as compared to a conventional flat cathode design. The enhanced electric field at the tip apex (2 GV/m) is about two orders of magnitude larger than the maximum electric field applicable in a plate capacitor based setup (20 MV/m). This reduces the influence of the initial energy distribution on the pulse duration at the target and improves the timing jitter. Simulations show that a setup with a sharp tip as the cathode in combination with two anodes yields an electron pulse duration of about 50 fs at the sample. The electron energy is 30 keV and the gun to sample distance is 3 cm. We implemented the two anode setup with the tip experimentally. We present the experimental characteristics of the emitted electron beam both in static field emission and in laser triggered emission.

  4. The CLIC positron source based on compton schemes

    CERN Document Server

    Rinolfi, L; Braun, H; Papaphilippou, Y; Schulte, D; Vivoli, A; Zimmermann, F; Dadoun, O; Lepercq, P; Roux, R; Variola, A; Zomer, F; Pogorelski, I; Yakimenko, V; Gai, W; Liu, W; Kamitani, T; Omori, T; Urakawa, J; Kuriki, M; Takahasi, TM; Bulyak, E; Gladkikh, P; Chehab, R; Clarke, J

    2010-01-01

    The CLIC polarized positron source is based on a positron production scheme in which polarized photons are produced by a Compton process. In one option, Compton backscattering takes place in a so-called “Compton ring”, where an electron beam of 1 GeV interacts with circularly-polarized photons in an optical resonator. The resulting circularly-polarized gamma photons are sent on to an amorphous target, producing pairs of longitudinally polarized electrons and positrons. The nominal CLIC bunch population is 4.2x109 particles per bunch at the exit of the Pre-Damping Ring (PDR). Since the photon flux coming out from a "Compton ring" is not sufficient to obtain the requested charge, a stacking process is required in the PDR. Another option is to use a Compton Energy Recovery Linac (ERL) where a quasicontinual stacking in the PDR could be achieved. A third option is to use a "Compton Linac" which would not require stacking. We describe the overall scheme as well as advantages and constraints of the three option...

  5. Compact X-ray source based on Compton backscattering

    CERN Document Server

    Bulyak, E V; Zelinsky, A; Karnaukhov, I; Kononenko, S; Lapshin, V G; Mytsykov, A; Telegin, Yu P; Khodyachikh, A; Shcherbakov, A; Molodkin, V; Nemoshkalenko, V; Shpak, A

    2002-01-01

    The feasibility study of an intense X-ray source based on the interaction between the electron beam in a compact storage ring and the laser pulse accumulated in an optical resonator is carried out. We propose to reconstruct the 160 MeV electron storage ring N-100, which was shutdown several years ago. A new magnetic lattice will provide a transverse of electron beam size of approx 35 mu m at the point of electron beam-laser beam interaction. The proposed facility is to generate X-ray beams of intensity approx 2.6x10 sup 1 sup 4 s sup - sup 1 and spectral brightness approx 10 sup 1 sup 2 phot/0.1%bw/s/mm sup 2 /mrad sup 2 in the energy range from 10 keV up to 0.5 MeV. These X-ray beam parameters meet the requirements for most of technological and scientific applications. Besides, we plan to use the new facility for studying the laser cooling effect.

  6. Lens-based wavefront sensorless adaptive optics swept source OCT

    Science.gov (United States)

    Jian, Yifan; Lee, Sujin; Ju, Myeong Jin; Heisler, Morgan; Ding, Weiguang; Zawadzki, Robert J.; Bonora, Stefano; Sarunic, Marinko V.

    2016-06-01

    Optical coherence tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. Although the axial resolution of OCT system, which is a function of the light source bandwidth, is sufficient to resolve retinal features at a micrometer scale, the lateral resolution is dependent on the delivery optics and is limited by ocular aberrations. Through the combination of wavefront sensorless adaptive optics and the use of dual deformable transmissive optical elements, we present a compact lens-based OCT system at an imaging wavelength of 1060 nm for high resolution retinal imaging. We utilized a commercially available variable focal length lens to correct for a wide range of defocus commonly found in patient’s eyes, and a novel multi-actuator adaptive lens for aberration correction to achieve near diffraction limited imaging performance at the retina. With a parallel processing computational platform, high resolution cross-sectional and en face retinal image acquisition and display was performed in real time. In order to demonstrate the system functionality and clinical utility, we present images of the photoreceptor cone mosaic and other retinal layers acquired in vivo from research subjects.

  7. Optimization of Malicious Traffic in Optimal Source Based Filtering

    Directory of Open Access Journals (Sweden)

    P.MOHANRAJ

    2014-01-01

    Full Text Available Traffic and spam are the main problems in the data transmission through the network. Many traffic filtering systems have been proposed to find and filter the traffic over the network. The system Optimal Source Filtering (OSF has implemented a new and optimal filtering mechanism. The new mechanism named as DROP, which monitors and filters the spam and malicious traffic over a network effectively. Traffic filtering systems have been proposed to detect the spammer and malicious traffic, using the optimal rules and policies. Further these systems are highly ineffective when they encounter malicious traffic. The proposed system introduced OSF protocol, which helps to improve the efficiency of the firewall and filters based on the user rule. The proposed filtering scheme provides TFS false filtering when the flash crowd occurred. The protocol verifies users and firewall rules and policies with the data priority model, which makes the filtering process more robust and fastest manner. The Proposed spam detection project identifies and eliminates unwanted messages by monitoring outgoing messages. The spam detection is the main challenging task in the network. In the existing system spam detection has implemented after the data received. According to the user rule and request the current system identifies the spam and zombies by monitoring every outgoing message from the sender.

  8. A novel amblyopia treatment system based on LED light source

    Science.gov (United States)

    Zhang, Xiaoqing; Chen, Qingshan; Wang, Xiaoling

    2011-05-01

    A novel LED (light emitting diode) light source of five different colors (white, red, green, blue and yellow) is adopted instead of conventional incandescent lamps for an amblyopia treatment system and seven training methods for rectifying amblyopia are incorporated so as for achieving an integrated therapy. The LED light source is designed to provide uniform illumination, adjustable light intensity and alterable colors. Experimental tests indicate that the LED light source operates steadily and fulfills the technical demand of amblyopia treatment.

  9. Neutron Source Facility Training Simulator Based on EPICS

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young Soo; Wei, Thomas Y.; Vilim, Richard B.; Grelle, Austin L.; Dworzanski, Pawel L.; Gohar, Yousry

    2015-01-01

    A plant operator training simulator is developed for training the plant operators as well as for design verification of plant control system (PCS) and plant protection system (PPS) for the Kharkov Institute of Physics and Technology Neutron Source Facility. The simulator provides the operator interface for the whole plant including the sub-critical assembly coolant loop, target coolant loop, secondary coolant loop, and other facility systems. The operator interface is implemented based on Experimental Physics and Industrial Control System (EPICS), which is a comprehensive software development platform for distributed control systems. Since its development at Argonne National Laboratory, it has been widely adopted in the experimental physics community, e.g. for control of accelerator facilities. This work is the first implementation for a nuclear facility. The main parts of the operator interface are the plant control panel and plant protection panel. The development involved implementation of process variable database, sequence logic, and graphical user interface (GUI) for the PCS and PPS utilizing EPICS and related software tools, e.g. sequencer for sequence logic, and control system studio (CSS-BOY) for graphical use interface. For functional verification of the PCS and PPS, a plant model is interfaced, which is a physics-based model of the facility coolant loops implemented as a numerical computer code. The training simulator is tested and demonstrated its effectiveness in various plant operation sequences, e.g. start-up, shut-down, maintenance, and refueling. It was also tested for verification of the plant protection system under various trip conditions.

  10. New source moderator geometry to improve performance of 252Cf and 241Am Be source-based PGNAA setups

    Science.gov (United States)

    Naqvi, A. A.; Abdelmonem, M. S.; Al-Misned, Ghada; Al-Ghamdi, Hanan

    2006-06-01

    The gamma ray yield from a 252Cf and a 241Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the 252Cf and the 241Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a 252Cf and a 241Am-Be source-based PGNAA setups.

  11. A Muon Source Proton Driver at JPARC-based Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, David [Fermilab

    2016-06-01

    An "ultimate" high intensity proton source for neutrino factories and/or muon colliders was projected to be a ~4 MW multi-GeV proton source providing short, intense proton pulses at ~15 Hz. The JPARC ~1 MW accelerators provide beam at parameters that in many respects overlap these goals. Proton pulses from the JPARC Main Ring can readily meet the pulsed intensity goals. We explore these parameters, describing the overlap and consider extensions that may take a JPARC-like facility toward this "ultimate" source. JPARC itself could serve as a stage 1 source for such a facility.

  12. Reconstruction and prediction of multi-source acoustic field with the distributed source boundary point method based nearfield acoustic holography

    Institute of Scientific and Technical Information of China (English)

    BI; Chuanxing; CHEN; Jian; CHEN; Xinzhao

    2004-01-01

    In a multi-source acoustic field, the actual measured pressure is a scalar sum of pressures from all the sources. The pressure belonging to every source cannot be separated out with the existing techniques. Consequently, routine formulas cannot be used to reconstruct the acoustic source and predict the acoustic field directly. In this paper, a novel theoretical model of reconstruction and prediction of multi-source acoustic field in the distributed source boundary point method (DSBPM) based nearfield acoustic holography (NAH) is established. Three different methods, namely combination method with single surface measurement, combination method with multi-surface measurement and elimination method with multi-surface measurement, are proposed to realize the holographic reconstruction of sources. With these methods, the problem of reconstruction and prediction of acoustic field existing multiple coherent sources synchronously is solved effectively. Using the particular solutions constructed by the DSBPM to establish the vibro-acoustic transfer matrix, the calculation time, calculation precision and calculation stability are improved. These methods are valuable in localizing acoustic source and predicting acoustic field in engineering field.

  13. The Prevalence and Phenomenology of Repetitive Behavior in Genetic Syndromes

    Science.gov (United States)

    Moss, Joanna; Oliver, Chris; Arron, Kate; Burbidge, Cheryl; Berg, Katy

    2009-01-01

    We investigated the prevalence and phenomenology of repetitive behavior in genetic syndromes to detail profiles of behavior. The Repetitive Behaviour Questionnaire (RBQ) provides fine-grained identification of repetitive behaviors. The RBQ was employed to examine repetitive behavior in Angelman (N = 104), Cornelia de Lange (N = 101), Cri-du-Chat…

  14. Producing ultrashort Terahertz to UV photons at high repetition rates for research into materials

    Energy Technology Data Exchange (ETDEWEB)

    G. R. Neil; C. Behre; S. V. Benson; G. Biallas; J. Boyce; L.A. Dillon-Townes; D. Douglas; H. F. Dylla; R. Evans; A. Grippo; D. Gruber; J. Gubeli; C. Hernandez-Garcia; K. Jordan; M. J. Kelley; L. Merminga; J. Mammosser; N. Nishimori; J. Preble; R. Rimmer; Michelle D. Shinn; T. Siggins; R. Walker; G. P. Williams; and S. Zhang

    2005-11-01

    A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on a Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160 MeV electron beam and an average current of 10 mA in 75 MHz repetition rate hundred femtosecond bunches. These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz {approx} half cycle pulse whose average brightness is > 5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20 W of average power extracted[1]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100 fs pulses with >200 W of average power (see G. P. Williams, this conference). The FELs also provide record-breaking laser power [2]: up to 10 kW of average power in the IR from 1 to 14 microns in 400 fs pulses at up to 74.85 MHz repetition rates and soon will produce similar pulses of 300-1000 nm light at up to 3 kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10 microseconds long at high repetition rates to continuous operation. The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser vapor deposition, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of

  15. Blind source separation based on generalized gaussian model

    Institute of Scientific and Technical Information of China (English)

    YANG Bin; KONG Wei; ZHOU Yue

    2007-01-01

    Since in most blind source separation (BSS) algorithms the estimations of probability density function (pdf) of sources are fixed or can only switch between one sup-Gaussian and other sub-Gaussian model,they may not be efficient to separate sources with different distributions. So to solve the problem of pdf mismatch and the separation of hybrid mixture in BSS, the generalized Gaussian model (GGM) is introduced to model the pdf of the sources since it can provide a general structure of univariate distributions. Its great advantage is that only one parameter needs to be determined in modeling the pdf of different sources, so it is less complex than Gaussian mixture model. By using maximum likelihood (ML) approach, the convergence of the proposed algorithm is improved. The computer simulations show that it is more efficient and valid than conventional methods with fixed pdf estimation.

  16. The Action Plan Against Repetitive Work - An Industrial Relation Strategy for Improving the Working Environment

    DEFF Research Database (Denmark)

    Hasle, Peter; Møller, Niels

    2001-01-01

    The Danish Action Plan against Repetitive Work is presented and discussed as a possible new strategy for regulating repetitive work as well as other complicated working environment problems. The article is based on an empirical evaluation ot the Action Plan. The asseessment of the Action Plan...... indicates that a measurable reduction of repetitive work has been achieved, while recognizing the the new management strategies focusing on human resources development have also played an important role. These results are used to suggest that - under certain conditions - a combination of state regulation...... and industrial relation agreements can be used to regulate other working environment problems....

  17. Animal models of restricted repetitive behavior in autism

    OpenAIRE

    Lewis, Mark H.; Tanimura, Yoko; Lee, Linda W.; Bodfish, James W.

    2006-01-01

    Restricted, repetitive behavior, along with deficits in social reciprocity and communication, is diagnostic of autism. Animal models relevant to this domain generally fall into three classes: repetitive behavior associated with targeted insults to the CNS; repetitive behavior induced by pharmacological agents; and repetitive behavior associated with restricted environments and experience. The extant literature provides potential models of the repetitive behavioral phenotype in autism rather t...

  18. Repetitive sequences in Eurasian lynx (Lynx lynx L.) mitochondrial DNA control region.

    Science.gov (United States)

    Sindičić, Magda; Gomerčić, Tomislav; Galov, Ana; Polanc, Primož; Huber, Duro; Slavica, Alen

    2012-06-01

    Mitochondrial DNA (mtDNA) control region (CR) of numerous species is known to include up to five different repetitive sequences (RS1-RS5) that are found at various locations, involving motifs of different length and extensive length heteroplasmy. Two repetitive sequences (RS2 and RS3) on opposite sides of mtDNA central conserved region have been described in domestic cat (Felis catus) and some other felid species. However, the presence of repetitive sequence RS3 has not been detected in Eurasian lynx (Lynx lynx) yet. We analyzed mtDNA CR of 35 Eurasian lynx (L. lynx L.) samples to characterize repetitive sequences and to compare them with those found in other felid species. We confirmed the presence of 80 base pairs (bp) repetitive sequence (RS2) at the 5' end of the Eurasian lynx mtDNA CR L strand and for the first time we described RS3 repetitive sequence at its 3' end, consisting of an array of tandem repeats five to ten bp long. We found that felid species share similar RS3 repetitive pattern and fundamental repeat motif TACAC.

  19. Prospects of Source-Separation-Based Sanitation Concepts: A Model-Based Study

    Directory of Open Access Journals (Sweden)

    Cees Buisman

    2013-07-01

    Full Text Available Separation of different domestic wastewater streams and targeted on-site treatment for resource recovery has been recognized as one of the most promising sanitation concepts to re-establish the balance in carbon, nutrient and water cycles. In this study a model was developed based on literature data to compare energy and water balance, nutrient recovery, chemical use, effluent quality and land area requirement in four different sanitation concepts: (1 centralized; (2 centralized with source-separation of urine; (3 source-separation of black water, kitchen refuse and grey water; and (4 source-separation of urine, feces, kitchen refuse and grey water. The highest primary energy consumption of 914 MJ/capita(cap/year was attained within the centralized sanitation concept, and the lowest primary energy consumption of 437 MJ/cap/year was attained within source-separation of urine, feces, kitchen refuse and grey water. Grey water bio-flocculation and subsequent grey water sludge co-digestion decreased the primary energy consumption, but was not energetically favorable to couple with grey water effluent reuse. Source-separation of urine improved the energy balance, nutrient recovery and effluent quality, but required larger land area and higher chemical use in the centralized concept.

  20. High-power 355 nm ultraviolet lasers operating at ultrahigh repetition rate

    Science.gov (United States)

    Chen, H.; Liu, Q.; Yan, P.; Gong, M.

    2013-02-01

    In this letter, we demonstrate a novel 355 nm ultraviolet (UV) laser operating at ultrahigh repetition rate from 300 kHz to 1 MHz. The hybrid fiber-MOPA-bulk amplifiers based IR source exhibits a high average power of 105 W with near-diffraction-limited beam quality, narrow linewidth and high polarization extinction ratio. Two-cascaded LBO crystals are employed for high efficiency frequency tripling, and a maximum 43.7 W of average UV power is achieved at 400 kHz, corresponding to a conversion efficiency as high as 41.6%. The pulse duration of the UV pulse can be tuned from 5 to 10 ns with good pulse peak stability (better than 2.2% (RMS)).

  1. MEG-based imaging of focal neuronal current sources

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, J.W.; Leahy, R.M. [University of Southern California, Los Angeles, CA (United States); Mosher, J.C. [Los Alamos National Lab., NM (United States)

    1996-07-01

    We describe a new approach to imaging neuronal current sources from measurements of the magnetoencephalogram (MEG) associated with sensory, motor, or cognitive brain activation. Previous approaches to this problem have concentrated on the use of weighted minimum norm inverse methods. While these methods ensure a unique solution, they do not introduce information specific to the MEG inverse problem, often producing overly smoothed solutions and exhibiting severe sensitivity to noise. We describe a Bayesian formulation of the inverse problem in which a Gibbs prior is constructed to reflect the sparse focal nature of neuronal current sources associated with evoked response data. The prior involves a binary process indicating active sources and a continuous Gaussian process designating associated amplitudes. An estimate of the primary current source distribution for a specific data set is formed by maximizing over the posterior probability with respect to the binary and continuous variables.

  2. Line-Source Based X-Ray Tomography

    OpenAIRE

    Deepak Bharkhada; Hengyong Yu; Hong Liu; Robert Plemmons; Ge Wang

    2009-01-01

    Current computed tomography (CT) scanners, including micro-CT scanners, utilize a point x-ray source. As we target higher and higher spatial resolutions, the reduced x-ray focal spot size limits the temporal and contrast resolutions achievable. To overcome this limitation, in this paper we propose to use a line-shaped x-ray source so that many more photons can be generated, given a data acquisition interval. In reference to the simultaneous algebraic reconstruction technique (SART) algorithm ...

  3. Combinatorial codon scrambling enables scalable gene synthesis and amplification of repetitive proteins

    Science.gov (United States)

    Tang, Nicholas C.; Chilkoti, Ashutosh

    2016-04-01

    Most genes are synthesized using seamless assembly methods that rely on the polymerase chain reaction (PCR). However, PCR of genes encoding repetitive proteins either fails or generates nonspecific products. Motivated by the need to efficiently generate new protein polymers through high-throughput gene synthesis, here we report a codon-scrambling algorithm that enables the PCR-based gene synthesis of repetitive proteins by exploiting the codon redundancy of amino acids and finding the least-repetitive synonymous gene sequence. We also show that the codon-scrambling problem is analogous to the well-known travelling salesman problem, and obtain an exact solution to it by using De Bruijn graphs and a modern mixed integer linear programme solver. As experimental proof of the utility of this approach, we use it to optimize the synthetic genes for 19 repetitive proteins, and show that the gene fragments are amenable to PCR-based gene assembly and recombinant expression.

  4. Powerful nanosecond light sources based on LEDs for astroparticle physics experiments

    OpenAIRE

    Lubsandorzhiev, B. K.; Poleshuk, R. V.; Shaibonov, B. A. J.; Vyatchin, Y. E.

    2007-01-01

    Powerful nanosecond light sources based on LEDs have been developed for use in astroparticle physics experiments. The light sources use either matrixes of ultra bright blue LEDs or a new generation high power blue LEDs. It's shown that such light sources have light yield of up to 10**10 - 10**12 photons per pulse with very fast light emission kinetics. The described light sources are important for use in calibration systems of Cherenkov and scintillator detectors. The developed light sources ...

  5. Repetitive motor behavior: further characterization of development and temporal dynamics.

    Science.gov (United States)

    Muehlmann, Amber M; Bliznyuk, Nikolay; Duerr, Isaac; Lewis, Mark H

    2015-03-01

    Repetitive behaviors are diagnostic for autism spectrum disorders, common in related neurodevelopmental disorders, and normative in typical development. In order to identify factors that mediate repetitive behavior development, it is necessary to characterize the expression of these behaviors from an early age. Extending previous findings, we characterized further the ontogeny of stereotyped motor behavior both in terms of frequency and temporal organization in deer mice. A three group trajectory model provided a good fit to the frequencies of stereotyped behavior across eight developmental time points. Group based trajectory analysis using a measure of temporal organization of stereotyped behavior also resulted in a three group solution. Additionally, as the frequency of stereotyped behavior increased with age, the temporal distribution of stereotyped responses became increasingly regular or organized indicating a strong association between these measures. Classification tree and principal components analysis showed that accurate classification of trajectory group could be done with fewer observations. This ability to identify trajectory group membership earlier in development allows for examination of a wide range of variables, both experiential and biological, to determine their impact on altering the expected trajectory of repetitive behavior across development. Such studies would have important implications for treatment efforts in neurodevelopmental disorders such as autism.

  6. Risk of shoulder tendinitis in relation to shoulder loads in monotonous repetitive work

    DEFF Research Database (Denmark)

    Frost, P.; Bonde, J. P.; Mikkelsen, S.;

    2002-01-01

    in repetitive work and 782 referents. Shoulder loads were quantified at task level and measures of exposures were assigned based on task distribution. Symptoms in combination with clinical criteria defined shoulder tendinitis. RESULTS: The prevalence of shoulder tendinitis was higher among exposed workers...... risk slightly (OR 1.6, 95% CI 1.0-2.6 per unit). CONCLUSIONS: The results indicate that workers with repetitive tasks have increased risk of shoulder tendinitis, which partially can be attributed to force requirements...

  7. Matriculation Research Report: Course Repetition Data & Analysis.

    Science.gov (United States)

    Gerda, Joe

    Due to concerns that its policy on class repetition was not promoting student success, California's College of the Canyons (CoC) undertook a project to analyze student course-taking patterns and make recommendations to modify the policy. Existing college policy did not follow Section 58161 of the State Educational Code that allows colleges to…

  8. The neurobiology of repetitive behavior : of mice…

    NARCIS (Netherlands)

    Langen, Marieke; Kas, Martien J H; Staal, Wouter G; van Engeland, Herman; Durston, Sarah

    2011-01-01

    Repetitive and stereotyped behavior is a prominent element of both animal and human behavior. Similar behavior is seen across species, in diverse neuropsychiatric disorders and in key phases of typical development. This raises the question whether these similar classes of behavior are caused by simi

  9. Large-scale detection of repetitions.

    Science.gov (United States)

    Smyth, W F

    2014-05-28

    Combinatorics on words began more than a century ago with a demonstration that an infinitely long string with no repetitions could be constructed on an alphabet of only three letters. Computing all the repetitions (such as ∙∙∙TTT ∙∙∙ or ∙∙∙ CGACGA ∙∙∙ ) in a given string x of length n is one of the oldest and most important problems of computational stringology, requiring time in the worst case. About a dozen years ago, it was discovered that repetitions can be computed as a by-product of the Θ(n)-time computation of all the maximal periodicities or runs in x. However, even though the computation is linear, it is also brute force: global data structures, such as the suffix array, the longest common prefix array and the Lempel-Ziv factorization, need to be computed in a preprocessing phase. Furthermore, all of this effort is required despite the fact that the expected number of runs in a string is generally a small fraction of the string length. In this paper, I explore the possibility that repetitions (perhaps also other regularities in strings) can be computed in a manner commensurate with the size of the output.

  10. Repetition effects in human ERPs to faces.

    Science.gov (United States)

    Schweinberger, Stefan R; Neumann, Markus F

    2016-07-01

    In the present paper, we review research conducted over the past 25 years addressing the effects of repeating various kinds of information in faces (e.g., pictorial, spatial configural, identity, semantic) on different components in human event-related brain potentials (ERPs). This body of evidence suggests that several ERP components are systematically linked to different functional components of face identity processing. Specifically, we argue (1) that repetition of the category of faces (categorical adaptation) strongly affects the occipitotemporal N170 amplitude, which is systematically suppressed when a face is preceded by another face, irrespective of its identity, whereas (2) the prototypicality of a face's second order spatial configuration has a prominent effect on the subsequent occipitotemporal P200. Longer-latency repetition effects are related to the processing of individual facial identities. These include (3) an ERP correlate of the transient activation of individual representations of repeated faces in the form of an enhanced occipitotemporal N250r as seen in repetition priming experiments, and (4) a correlate of the acquisition of individual face identity representations during learning as seen in a topographically similar long-lasting N250 effect. Finally, (5) the repetition of semantic information in familiar person recognition elicits a central-parietal N400 ERP effect. We hope that this overview will encourage researchers to further exploit the potential of ERPs to provide a continuous time window to neuronal correlates of multiple processes in face perception under comparatively natural viewing conditions. PMID:26672902

  11. A Carbon Nanotube Electron Source Based Ionization Vacuum Gauge

    Energy Technology Data Exchange (ETDEWEB)

    Changkun Dong; Ganapati Myneni

    2003-10-01

    The results of fabrication and performance of an ionization vacuum gauge using a carbon nanotube (CNT) electron source are presented. The electron source was constructed with multi-wall nanotubes (MWNT), which were grown using thermal chemical vapor deposition (CVD) process. The electron emission of the source was stable in vacuum pressure up to 10-7 Torr, which is better than the metal field emitters. The measurement linearity of the gauge was better than {+-}10% from 10-6 to 10-10 Torr. The gauge sensitivity of 4 Torr-1 was achieved under 50 {micro}A electron emission in nitrogen. The gauge is expected to find applications in vacuum measurements from 10-7 Torr to below 10-11 Torr.

  12. Pitch and TDOA-Based Localization of Acoustic Sources with Distributed Arrays

    DEFF Research Database (Denmark)

    Hansen, Martin Weiss; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2015-01-01

    In this paper, a method for acoustic source localization using distributed microphone arrays based on time-differences of arrival (TDOAs) is presented. The TDOAs are used to estimate the location of an acoustic source using a recently proposed method, based on a 4D parameter space defined by the 3D...... location of the source, and the TDOAs. The performance of the proposed method for acoustic source localization is compared to the performance of a method based on generalized cross-correlation with phase transform (GCC-PHAT) using synthetic and speech signals with varying source position. Results show...

  13. Model Based Diagnosis of an Air Source Heat Pump

    OpenAIRE

    Alfredsson, Sandra

    2011-01-01

    The purpose of a heat pump is to control the temperature of an enclosed space. This is done by using heat exchange with a heat source, for example water, air, or ground. In the air source heat pump that has been studied during this master thesis, a refrigerant exchanges heat with the outdoor air and with a water distribution system. The heat pump is controlled through the circuit containing the refrigerant and it is therefore crucial that this circuit is functional. To ensure this, a diagnosi...

  14. Optical unmixing using programmable spectral source based on DMD

    Science.gov (United States)

    Luo, Ding; Bauer, Sebastian; Taphanel, Miro; Längle, Thomas; Puente León, Fernando; Beyerer, Jürgen

    2016-05-01

    Traditional spectral unmixing involves intense signal processing applied on multispectral or hyperspectral data captured from an imaging device, which is highly time-consuming. In this article, a novel method, namely "optical unmixing", is proposed to alleviate the post processing effort by replacing the heavy computation with a spectrally tunable light source. By choosing spectral features of the light source intelligently, the abundance map of each material can be retrieved with minimum computation from gray value images captured by a normal camera. For n unknown endmembers, 3n + 1 measurements are required to retrieve the abundance maps with proposed algorithms.

  15. IR light source based on LED for endoscopy applications

    OpenAIRE

    Ruiz López, Mabel

    2009-01-01

    Tesina final de master feta en col.laboració amb Transmural Biotech S.L A specific endoscopy technology uses an InfraRed (IR) light to achieve specific imaging of the vascular system. This IR light is obtained by an IR laser source. The aim of this study is to find a new IR illumination built with LEDs to substitute the existing IR source. LEDs may contribute in the endoscopy application with their advantage: LEDs cost is lower than lasers, LEDs have a longer lifetime, LEDs are...

  16. About the Infinite Repetition of Histories in Space

    Directory of Open Access Journals (Sweden)

    Manuel Alfonseca

    2014-08-01

    Full Text Available This paper analyzes two different proposals, one by Ellis and Brundrit, based on classical relativistic cosmology, the other by Garriga and Vilenkin, based on the DH interpretation of quantum mechanics, both concluding that, in an infinite universe, planets and beings must be repeated an infinite number of times. We point to possible shortcomings in these arguments. We conclude that the idea of an infinite repetition of histories in space cannot be considered strictly speaking a consequence of current physics and cosmology. Such ideas should be seen rather as examples of «ironic science» in the terminology of John Horgan.

  17. Impacts of DEM uncertainties on critical source areas identification for non-point source pollution control based on SWAT model

    Science.gov (United States)

    Xu, Fei; Dong, Guangxia; Wang, Qingrui; Liu, Lumeng; Yu, Wenwen; Men, Cong; Liu, Ruimin

    2016-09-01

    The impacts of different digital elevation model (DEM) resolutions, sources and resampling techniques on nutrient simulations using the Soil and Water Assessment Tool (SWAT) model have not been well studied. The objective of this study was to evaluate the sensitivities of DEM resolutions (from 30 m to 1000 m), sources (ASTER GDEM2, SRTM and Topo-DEM) and resampling techniques (nearest neighbor, bilinear interpolation, cubic convolution and majority) to identification of non-point source (NPS) critical source area (CSA) based on nutrient loads using the SWAT model. The Xiangxi River, one of the main tributaries of Three Gorges Reservoir in China, was selected as the study area. The following findings were obtained: (1) Elevation and slope extracted from the DEMs were more sensitive to DEM resolution changes. Compared with the results of the 30 m DEM, 1000 m DEM underestimated the elevation and slope by 104 m and 41.57°, respectively; (2) The numbers of subwatersheds and hydrologic response units (HRUs) were considerably influenced by DEM resolutions, but the total nitrogen (TN) and total phosphorus (TP) loads of each subwatershed showed higher correlations with different DEM sources; (3) DEM resolutions and sources had larger effects on CSAs identifications, while TN and TP CSAs showed different response to DEM uncertainties. TN CSAs were more sensitive to resolution changes, exhibiting six distribution patterns at all DEM resolutions. TP CSAs were sensitive to source and resampling technique changes, exhibiting three distribution patterns for DEM sources and two distribution patterns for DEM resampling techniques. DEM resolutions and sources are the two most sensitive SWAT model DEM parameters that must be considered when nutrient CSAs are identified.

  18. Compact and high-power broadband terahertz source based on femtosecond photonic crystal fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    Feng Liu; Lu Chai; Qirong Xing; Chingyue Wang; Weili Zhang; Xiaokun Hu; Jiang Li; Changlei Wang; Yi Li; Yanfeng Li; YoujianSong; Bowen Liu; Minglie Hu

    2011-01-01

    Terahertz (THz) waves,generally defined in the 0.1-10 THz range are finding growing applications in various important fields[1-4] such as imaging,food and pharmaceutical quality coutrol,security screening,and standoff detection of bio-threat species,among which THz timedomain spectroscopy (THz-TDS)[5] is particularly appealing.However,the low conversion efficiency and low power of typical broadband THz sources severely hinder the utility and realization of the full potential of THzTDS.Recently,there have been efforts to generate THz pulses using compact pump sources in fiber format[6,7].%We present a review of the development of a compact and high-power broadband terahertz (THz) source optically excited by a femtosecond photonic crystal fiber (PCF) amplifier. The large mode area of the PCF and the stretcher-free configuration make the pump source compact and very efficient. Broadband THz pulseg of 150 μW extending from 0.1 to 3.5 TH2 are generated from a 3-mm-thick GaP crystal through optical rectification of 12-W pump pulses with duration of 66 & and a repetition rate of 52 MHz. A strong saturation effect is observed, which is attributed to pump pulse absorption; a Z-scan measurement shows that three-photon absorption dominates the nonlinear absorption when the crystal is pumped by femtosecond pulses at 1040 run. A further scale-up of the THz source power is expected to find important applications in THz nonlinear optics and nonlinear THz spectroscope

  19. LIGHT SOURCE: Design of a new compact THz source based on Smith-Purcell radiation

    Science.gov (United States)

    Dai, Dong-Dong; Bei, Hua; Dai, Zhi-Min

    2009-06-01

    In recent years, people are dedicated to the research work of finding compact THz sources with high emission power. Smith-Purcell radiation is qualified for the possibility of coherent enhancement due to the effect of FEL mechanism. The compact experiment device is expected to produce hundreds mW level THz ray. The electron beam with good quality is provided under the optimized design of the electron gun. Besides, the grating is designed as an oscillator without any external feedbacks. While the beam passes through the grating surface, the beam bunching will be strong and the second harmonics enhancement will be evident, as is seen from the simulation results.

  20. Photonic crystal fibre-based light source for STED lithography

    Energy Technology Data Exchange (ETDEWEB)

    Glubokov, D A; Sychev, V V; Vitukhnovsky, Alexey G; Korol' kov, A E

    2013-06-30

    A light source having a relative noise level in the order of 10{sup -6} and sufficient stability for application in STED lithography has been obtained using the generation of Cherenkov peaks in a supercontinuum spectrum. (laser applications and other topics in quantum electronics)

  1. High-Speed Fuses in IGBT based Voltage Source Converters

    DEFF Research Database (Denmark)

    Iov, Florin; Blaabjerg, Frede; Rasmussen, Henrik

    2005-01-01

    . By introducing fuses into voltage source converters a better protection of IGBTs can be achieved. This paper is a complete overview of a research project carried out in cooperation by Aalborg University, Denmark and Cooper Bussmann International. This paper discusses three main issues regarding the IGBT fuse...

  2. Pulsed neutron sources at Dubna

    International Nuclear Information System (INIS)

    In 1960 the first world repetitively pulsed reactor IBR was put into operation. It was the beginning of the story how fission based pulsed neutron sources at Dubna have survived. The engineers involved have experienced many successes and failures in the course of new sources upgrading to finally come to possess the world's brightest neutron source - IBR-2. The details are being reviewed through the paper. The fission based pulsed neutron sources did not reach their final state as yet- the conceptual views of IBR prospects are being discussed with the goal to double the thermal neutron peak flux (up to 2x1016) and to enhance the cold neutron flux by 10 times (with the present one being as high that of the ISIS cold moderator). (author)

  3. A battery-based, low-noise voltage source

    Science.gov (United States)

    Wagner, Anke; Sturm, Sven; Schabinger, Birgit; Blaum, Klaus; Quint, Wolfgang

    2010-06-01

    A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of ±15 and ±5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7×10-7 over 6.5 h and a noise level equal or smaller than 30 nV/√Hz is achieved.

  4. The Great Patriotic War: the Problems of Forming the Source Base

    Directory of Open Access Journals (Sweden)

    Evgeny F. Krinko

    2015-07-01

    Full Text Available The Great Patriotic War was reflected in the different historical sources. The article is devoted to the formation of the source base of the problem. The author examines the dynamics of the situation in the archives and publication of documents. The main attention is paid to the modern study of the sources of the Great Patriotic War.

  5. Pulsed neutron source based on accelerator-subcritical-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Makoto; Noda, Akira; Iwashita, Yoshihisa; Okamoto, Hiromi; Shirai, Toshiyuki [Kyoto Univ., Uji (Japan). Inst. for Chemical Research

    1997-03-01

    A new pulsed neutron source which consists of a 300MeV proton linac and a nuclear fuel subcritical assembly is proposed. The proton linac produces pulsed spallation neutrons, which are multipied by the subcritical assembly. A prototype proton linac that accelerates protons up to 7MeV has been developed and a high energy section of a DAW structure is studied with a power model. Halo formations in high intensity beam are also being studied. (author)

  6. Heavy Ion Injection Into Synchrotrons, Based On Electron String Ion Sources

    CERN Document Server

    Donets, E E; Syresin, E M

    2004-01-01

    A possibility of heavy ions injection into synchrotrons is discussed on the base of two novel ion sources, which are under development JINR during last decade: 1) the electron string ion source (ESIS), which is a modified version of a conventional electron beam ion source (EBIS), working in a reflex mode of operation, and 2) the tubular electron string ion source (TESIS). The Electron String Ion Source "Krion-2" (VBLHE, JINR, Dubna) with an applied confining magnetic field of 3 T was used for injection into the superconducting JINR synchrotron - Nuclotron and during this runs the source provided a high pulse intensity of the highly charged ion beams: Ar16+

  7. Pulse compression below 5 fs at MHz repetition rate: current status, prospects, and applications

    OpenAIRE

    Baltuška, Andrius; Pshenichnikov, Maxim S.; Wiersma, Douwe A.; Szipöcs, Róbert

    1998-01-01

    The sub-5-fs pulses are used in nonlinear optical experiments to study ultrafast chemical reaction dynamics in solutions. The high repetition rate, simplicity, and large spectral bandwidth (>500 nm) make this light source ideal for spectroscopic applications in condensed phase.

  8. Polymer and small molecule based hybrid light source

    Science.gov (United States)

    Choong, Vi-En; Choulis, Stelios; Krummacher, Benjamin Claus; Mathai, Mathew; So, Franky

    2010-03-16

    An organic electroluminescent device, includes: a substrate; a hole-injecting electrode (anode) coated over the substrate; a hole injection layer coated over the anode; a hole transporting layer coated over the hole injection layer; a polymer based light emitting layer, coated over the hole transporting layer; a small molecule based light emitting layer, thermally evaporated over the polymer based light emitting layer; and an electron-injecting electrode (cathode) deposited over the electroluminescent polymer layer.

  9. 100 kV/2A three-phase constant-current repetitive-rate charging equipment

    International Nuclear Information System (INIS)

    A 100 kV/2A three-phase constant-current repetitive-rate charging equipment was designed and constructed. A three-phase L-C converter is adopted as constant-current power source. Six Insulated Gate Bipolar Transistors (IGBTs) are connected in parallel to control the stop of charge. A Programmable Logical Controller (PLC) is the central element of the control unit. The equipment is used in the repetitive-rate discharge features test of the switch. It works stably under the conditions of 2A charging current, 10 Hz operating voltage, 100 kV repetitive rate and 1μF capacitor

  10. 100 kV/2A three-phase constant-current repetitive-rate charging equipment

    CERN Document Server

    Tan Yu Gang; Chen Li Dong; Guo Zhi Gang; Zou Xiao Bing; Luo Min; Cao Shao Yun; Chang An Bi

    2002-01-01

    A 100 kV/2A three-phase constant-current repetitive-rate charging equipment was designed and constructed. A three-phase L-C converter is adopted as constant-current power source. Six Insulated Gate Bipolar Transistors (IGBTs) are connected in parallel to control the stop of charge. A Programmable Logical Controller (PLC) is the central element of the control unit. The equipment is used in the repetitive-rate discharge features test of the switch. It works stably under the conditions of 2A charging current, 10 Hz operating voltage, 100 kV repetitive rate and 1 mu F capacitor

  11. The hypertext information system on pulsed neutron sources and scientific investigations based on these sources

    International Nuclear Information System (INIS)

    The work on the creation of the hypertext information system has been performed on the basis of the web-server of the Frank Laboratory of Neutron Physics, JINR. The initial project proposed the creation of HTML information resources and did not consider the usage of any database for the information management. During the project implementation it became obvious that the system should have well defined structured informational model and it might be helpful to imply the relational database as a part of the system. The ORACLE server at the Laboratory of Computing Techniques and Automation (LCTA) of the JINR has been used for this task. Now we have a set of ORACLE tables designed using CASE tools for the informational model of the system, structured information about neutron sources, neutron instruments, printed publications and URL addresses. We have also the web interface to these tables using free ware gateway ORALINK installed on our Pentium PC with Windows NT and some tools to administer database and view pictures stored in the tables. We took into account NeXuS specifications while tried to design the informational model of the system, and we continue to work on its creation

  12. Robust Repetitive Controller for Fast AFM Imaging

    CERN Document Server

    Necipoglu, Serkan; Has, Yunus; Guvenc, Levent; Basdogan, Cagatay

    2012-01-01

    Currently, Atomic Force Microscopy (AFM) is the most preferred Scanning Probe Microscopy (SPM) method due to its numerous advantages. However, increasing the scanning speed and reducing the interaction forces between the probe's tip and the sample surface are still the two main challenges in AFM. To meet these challenges, we take advantage of the fact that the lateral movements performed during an AFM scan is a repetitive motion and propose a Repetitive Controller (RC) for the z-axis movements of the piezo-scanner. The RC utilizes the profile of the previous scan line while scanning the current line to achieve a better scan performance. The results of the scanning experiments performed with our AFM set-up show that the proposed RC significantly outperforms a conventional PI controller that is typically used for the same task. The scan error and the average tapping forces are reduced by 66% and 58%, respectively when the scan speed is increased by 7-fold.

  13. Quantum-dot-based integrated non-linear sources

    DEFF Research Database (Denmark)

    Bernard, Alice; Mariani, Silvia; Andronico, Alessio;

    2015-01-01

    The authors report on the design and the preliminary characterisation of two active non-linear sources in the terahertz and near-infrared range. The former is associated to difference-frequency generation between whispering gallery modes of an AlGaAs microring resonator, whereas the latter is...... granted by parametric generation in a waveguide via modal phase matching. Both devices rely on embedded quantum-dot lasers, which allow for low-threshold currents and unconventional geometries. They also include specific degrees of freedom that open a practical route towards phase matching, either during...

  14. Silicon-Based Light Sources for Silicon Integrated Circuits

    Directory of Open Access Journals (Sweden)

    L. Pavesi

    2008-01-01

    Full Text Available Silicon the material per excellence for electronics is not used for sourcing light due to the lack of efficient light emitters and lasers. In this review, after having introduced the basics on lasing, I will discuss the physical reasons why silicon is not a laser material and the approaches to make it lasing. I will start with bulk silicon, then I will discuss silicon nanocrystals and Er3+ coupled silicon nanocrystals where significant advances have been done in the past and can be expected in the near future. I will conclude with an optimistic note on silicon lasing.

  15. Producing Terahertz Conherent Synchrotron Radiation Based On Hefei Light Source

    CERN Document Server

    De-Rong, Xu; Yan, Shao

    2014-01-01

    This paper theoretically proves that an electron storage ring can generate coherent radiation in THz region using a quick kicker magnet and an ac sextupole magnet. When the vertical chromaticity is modulated by the ac sextupole magnet, the vertical beam collective motion excited by the kicker produces a wavy spatial structure after a number of longitudinal oscillation periods. We calculate the radiation spectral distribution from the wavy bunch in Hefei Light Source(HLS). If we reduce electron energy to 400MeV, it can produce extremely strong coherent synchrotron radiation(CSR) at 0.115THz.

  16. The differential effects of fluency due to repetition and fluency due to color contrast on judgments of truth.

    Science.gov (United States)

    Silva, Rita R; Garcia-Marques, Teresa; Mello, Joana

    2016-09-01

    Two experiments contrast the effects of fluency due to repetition and fluency due to color contrast on judgments of truth, after participants learn to associate high levels of fluency with falseness (i.e., a reversal of the fluency-truth link). Experiment 1 shows that the interpretation of fluency as a sign of truth is harder to reverse when learning is promoted with repetition rather than with perceptual fluency. Experiment 2 shows that when color contrast and repetition are manipulated orthogonally, the reversal of the truth effect learned with color contrast does not generalize to repetition. These results suggest specificities in the processing experiences generated by different sources of fluency, and that their influences can be separated in contexts that allow the contrast of their distinctive features. We interpret and discuss these results in light of the research addressing the convergence vs. dissociation of the effects elicited by different fluency sources.

  17. A repetitive elements perspective in Polycomb epigenetics.

    Directory of Open Access Journals (Sweden)

    Valentina eCasa

    2012-10-01

    Full Text Available Repetitive elements comprise over two-thirds of the human genome. For a long time, these elements have received little attention since they were considered non functional. On the contrary, recent evidence indicates that they play central roles in genome integrity, gene expression and disease. Indeed, repeats display meiotic instability associated with disease and are located within common fragile sites, which are hotspots of chromosome rearrangements in tumors. Moreover, a variety of diseases have been associated with aberrant transcription of repetitive elements. Overall this indicates that appropriate regulation of repetitive elements’ activity is fundamental.Polycomb group (PcG proteins are epigenetic regulators that are essential for the normal development of multicellular organisms. Mammalian PcG proteins are involved in fundamental processes, such as cellular memory, cell proliferation, genomic imprinting, X-inactivation, and cancer development. PcG proteins can convey their activity through long-distance interactions also on different chromosomes. This indicates that the 3D organization of PcG proteins contributes significantly to their function. However, it is still unclear how these complex mechanisms are orchestrated and which role PcG proteins play in the multi-level organization of gene regulation. Intriguingly, the greatest proportion of Polycomb-mediated chromatin modifications is located in genomic repeats and it has been suggested that they could provide a binding platform for Polycomb proteins.Here, these lines of evidence are woven together to discuss how repetitive elements could contribute to chromatin organization in the 3D nuclear space.

  18. Arrangement of repetitive sequences in the genome of herpesvirus Sylvilagus.

    Science.gov (United States)

    Medveczky, M M; Geck, P; Clarke, C; Byrnes, J; Sullivan, J L; Medveczky, P G

    1989-02-01

    Herpesvirus sylvilagus is a lymphotropic (type gamma) herpesvirus of cottontail rabbits (Sylvilagus floridanus). Analysis of virion DNA of herpesvirus sylvilagus has revealed that the genome consists of one stretch of about 120 kilobase pairs of internal, unique DNA flanked by a variable number of 553-base-pair tandem repeats. The G + C content of the repetitive DNA is extremely high (83%), as determined by sequencing. The organization of the herpesvirus sylvilagus genome is, therefore, similar to that of the primate lymphotropic viruses herpesvirus saimiri and herpesvirus ateles. PMID:2911114

  19. Research on Passivity Based Controller of Three Phase Voltage Source PWM Rectifier

    Directory of Open Access Journals (Sweden)

    Yin Hongren

    2012-09-01

    Full Text Available Euler-Lagrange (EL model of voltage source PWM rectifier is set up based on its model in synchronous dq coordinates. Passivity based controller is designed on the basis of passivity and EL model of voltage source PWM rectifier. Three switching function are educed by passivity based controller. A switching function is only realized in engineering consequently. Voltage source PWM rectifier using passivity based controller has many advantages, such as simpler structure, low total harmonic distortion, and good disturbance rejection performance. Passivity based control law is proved feasible by simulink simulation.  

  20. Developing a beta source based setup for pixel sensor characterization

    CERN Document Server

    Schouwenberg, Jeroen

    2014-01-01

    The main goal of this project is to provide mono-energetic minimum ionizing electrons from a $^{90}$Sr source using a magnetic monochromator, and thus provide a useful tool for in-lab sensor characterization. The monochromator is calibrated using a setup, with a heavy inorganic scintillator and a PMT, which has been calibrated with a $^{22}$Na gamma source. The average energy of the electrons as a function of the current in the monochromator coil is found to be $1.38\\pm0.01$ keV/mA, taking into consideration the effect of the magnetic field on the signal of the PMT. For integration into the pixel sensor test bench, scintillator-counters (a plastic scintillator connected to a PMT) are used. Their response to the electron energies is observed to follow a saturation curve, which leads to a more identical response for high energetic electrons. A preliminary pixel sensor test bench has been set up and properties such as voltage and discriminator settings have been studied as well as count rates for coincidence cou...

  1. ECR ion source based low energy ion beam facility

    Indian Academy of Sciences (India)

    P Kumar; G Rodrigues; U K Rao; C P Safvan; D Kanjilal; A Roy

    2002-11-01

    Mass analyzed highly charged ion beams of energy ranging from a few keV to a few MeV plays an important role in various aspects of research in modern physics. In this paper a unique low energy ion beam facility (LEIBF) set up at Nuclear Science Centre (NSC) for providing low and medium energy multiply charged ion beams ranging from a few keV to a few MeV for research in materials sciences, atomic and molecular physics is described. One of the important features of this facility is the availability of relatively large currents of multiply charged positive ions from an electron cyclotron resonance (ECR) source placed entirely on a high voltage platform. All the electronic and vacuum systems related to the ECR source including 10 GHz ultra high frequency (UHF) transmitter, high voltage power supplies for extractor and Einzel lens are placed on a high voltage platform. All the equipments are controlled using a personal computer at ground potential through optical fibers for high voltage isolation. Some of the experimental facilities available are also described.

  2. FRB repetition and non-Poissonian statistics

    CERN Document Server

    Connor, Liam; Oppermann, Niels

    2016-01-01

    We discuss some of the claims that have been made regarding the statistics of fast radio bursts (FRBs). In an earlier paper \\citep{2015arXiv150505535C} we conjectured that flicker noise associated with FRB repetition could show up in non-cataclysmic neutron star emission models, like supergiant pulses. We show how the current limits of repetition would be significantly weakened if their repeat rate really were non-Poissonian and had a pink or red spectrum. Repetition and its statistics have implications for observing strategy, generally favouring shallow wide-field surveys, since in the non-repeating scenario survey depth is unimportant. We also discuss the statistics of the apparent latitudinal dependence of FRBs, and offer a simple method for calculating the significance of this effect. We provide a generalized Bayesian framework for addressing this problem, which allows for direct model comparison. It is shown how the evidence for a steep latitudinal gradient of the FRB rate is less strong than initially s...

  3. Can predictive coding explain repetition suppression?

    Science.gov (United States)

    Grotheer, Mareike; Kovács, Gyula

    2016-07-01

    While in earlier work various local or bottom-up neural mechanisms were proposed to give rise to repetition suppression (RS), current theories suggest that top-down processes play a role in determining the repetition related reduction of the neural responses. In the current review we summarise those results, which support the role of these top-down processes, concentrating on the Bayesian models of predictive coding (PC). Such models assume that RS is related to the statistical probabilities of prior stimulus occurrences and to the future predictability of these stimuli. Here we review the current results that support or argue against this explanation. We point out that the heterogeneity of experimental manipulations that are thought to reflect predictive processes are likely to measure different processing steps, making their direct comparison difficult. In addition we emphasize the importance of identifying these sub-processes and clarifying their role in explaining RS. Finally, we propose a two-stage model for explaining the relationships of repetition and expectation phenomena in the human cortex. PMID:26861559

  4. High field, high repetition rate kicker

    CERN Document Server

    Ishi, Y; Muto, M; Shirakabe, Y; Takagi, A

    2001-01-01

    New kicker magnet systems and their related technologies are being developed and tested at KEK. The kickers are to be used both for the injection and for the fast extraction of two rings, the 50 GeV proton synchrotron in the 'Joint Project' of JAERI-KEK and the PRISM/FFAG ring for the muon beam. In order to obtain a sufficient kick on the high-intensity beam in the 50 GeV proton ring, the kicker systems must have both large apertures and high fields. In addition to this, the PRISM/FFAG ring demands muon beams with a high repetition rate of injection and extraction. The requested repetition rate is 1 kHz or higher. In order to fulfill those demands, new technologies have been introduced and are now being tested. Among them are high-power IGBT modules, a subordinated-gating system, 1 kHz repetition pulsed power supply, and kickers with magnetic-alloy cores used as return yokes.

  5. Repetitive transcranial magnetic stimulation for hallucination in schizophrenia spectrum disorders A meta-analysis***

    Institute of Scientific and Technical Information of China (English)

    Yingli Zhang; Wei Liang; Shichang Yang; Ping Dai; Lijuan Shen; Changhong Wang

    2013-01-01

    OBJECTIVE: This study assessed the efficacy and tolerability of repetitive transcranial magnetic stimulation for treatment of auditory hal ucination of patients with schizophrenia spectrum disorders. DATA SOURCES: Online literature retrieval was conducted using PubMed, ISI Web of Science, EMBASE, Medline and Cochrane Central Register of Control ed Trials databases from January 1985 to May 2012. Key words were “transcranial magnetic stimulation”, “TMS”, “repetitive transcranial magnetic stimulation”, and “hal ucination”. STUDY SELECTION: Selected studies were randomized control ed trials assessing therapeutic ef-ficacy of repetitive transcranial magnetic stimulation for hal ucination in patients with schizophrenia spectrum disorders. Experimental intervention was low-frequency repetitive transcranial magnetic stimulation in left temporoparietal cortex for treatment of auditory hal ucination in schizophrenia spectrum disorders. Control groups received sham stimulation. MAIN OUTCOME MEASURES: The primary outcome was total scores of Auditory Hal ucinations Rating Scale, Auditory Hal ucination Subscale of Psychotic Symptom Rating Scale, Positive and Negative Symptom Scale-Auditory Hal ucination item, and Hal ucination Change Scale. Secondary outcomes included response rate, global mental state, adverse effects and cognitive function. RESULTS: Seventeen studies addressing repetitive transcranial magnetic stimulation for treatment of schizophrenia spectrum disorders were screened, with controls receiving sham stimulation. Al data were completely effective, involving 398 patients. Overal mean weighted effect size for repeti-tive transcranial magnetic stimulation versus sham stimulation was statistical y significant (MD =-0.42, 95%CI: -0.64 to -0.20, P = 0.000 2). Patients receiving repetitive transcranial magnetic stimulation responded more frequently than sham stimulation (OR = 2.94, 95%CI: 1.39 to 6.24, P =0.005). No significant differences were found

  6. Repetitive behaviour in autism: Imaging pathways and trajectories

    NARCIS (Netherlands)

    Langen, M.J.G.

    2009-01-01

    Repetitive behaviour in autism: Imaging pathways and trajectories Repetitive and rigid behaviour is one of the core symptoms of autism, a severe and lifelong child psychiatric disorder. Although repetitive behaviour symptoms often form a significant impairment for affected individuals, systematic st

  7. Lingual Kinematics during Rapid Syllable Repetition in Parkinson's Disease

    Science.gov (United States)

    Wong, Min Ney; Murdoch, Bruce E.; Whelan, Brooke-Mai

    2012-01-01

    Background: Rapid syllable repetition tasks are commonly used in the assessment of motor speech disorders. However, little is known about the articulatory kinematics during rapid syllable repetition in individuals with Parkinson's disease (PD). Aims: To investigate and compare lingual kinematics during rapid syllable repetition in dysarthric…

  8. Fusion Based Neutron Sources for Security Applications: Neutron Techniques

    OpenAIRE

    Albright, S.; Seviour, Rebecca

    2014-01-01

    The current reliance on X-Rays and intelligence for na- tional security is insufficient to combat the current risks of smuggling and terrorism seen on an international level. There are a range of neutron based security techniques which have the potential to dramatically improve national security. Neutron techniques can be broadly grouped into neutron in/neutron out and neutron in/photon out tech- niques. The use of accelerator based fusion devices will potentially enable to wide spread applic...

  9. Properties and Applications of Laser Generated X-Ray Sources

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R F; Key, M H

    2002-02-25

    The rapid development of laser technology and related progress in research using lasers is shifting the boundaries where laser based sources are preferred over other light sources particularly in the XUV and x-ray spectral region. Laser based sources have exceptional capability for short pulse and high brightness and with improvements in high repetition rate pulsed operation, such sources are also becoming more interesting for their average power capability. This study presents an evaluation of the current capabilities and near term future potential of laser based light sources and summarizes, for the purpose of comparison, the characteristics and near term prospects of sources based on synchrotron radiation and free electron lasers. Conclusions are drawn on areas where the development of laser based sources is most promising and competitive in terms of applications potential.

  10. Compact, high power electron beam based terahertz sources.

    Energy Technology Data Exchange (ETDEWEB)

    Biedron, S. G.; Lewellen, J. W.; Milton, S. V.; Gopalsami, N.; Schneider, J. F.; Skubal, L.; Li, Y. L.; Virgo, M.; Gallerano, G. P.; Doria, A.; Giovenale, E.; Messina, G.; Spasovsky, I. P.; Office of The Director-Applied Science and Technology; Univ. of Maryland; ENEA

    2007-08-01

    Although terahertz (THz) radiation was first observed about 100 years ago, this portion of the electromagnetic spectrum at the boundary between the microwaves and the infrared has been, for a long time, rather poorly explored. This situation changed with the rapid development of coherent THz sources such as solid-state oscillators, quantum cascade lasers, optically pumped solid-state devices, and novel coherent radiator devices. These in turn have stimulated a wide variety of applications from material science to telecommunications, from biology to biomedicine. Recently, there have been two related compact coherent radiation devices invented able to produce up to megawatts of peak THz power by inducing a ballistic bunching effect on the electron beam, forcing the beam to radiate coherently. An introduction to the two systems and the corresponding output photon beam characteristics will be provided.

  11. Natural Radioactivity Source Term Based on Remote Sensing Data

    International Nuclear Information System (INIS)

    The paper describes the basic principles for applying satellite remote sensing technology to the investigation of natural radioactivity. The relationship between areas of natural background anomalies and geological characteristics is analysed systematically. The supervised classification method and spectral angle mapping are used for the extraction of remote sensing information. Geological features with elevated levels of gamma radiation can be identified on small scale maps. On-site inspections have been launched. The relationship between natural radiation level and radiation source term is becoming clearer. The study provides exact locations and targets for protection and control in areas with elevated levels of gamma radiation. The project has the potential for expanding the range of services in environmental geochemistry and remote sensing geology. It opens up a new approach for conducting research on natural radioactivity. (author)

  12. FEASIBILITY STUDY II OF A MUON BASED NEUTRINO SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    GALLARDO,J.C.; OZAKI,S.; PALMER,R.B.; ZISMAN,M.

    2001-06-30

    The concept of using a muon storage ring to provide a well characterized beam of muon and electron neutrinos (a Neutrino Factory) has been under study for a number of years now at various laboratories throughout the world. The physics program of a Neutrino Factoryis focused on the relatively unexplored neutrino sector. In conjunction with a detector located a suitable distance from the neutrino source, the facility would make valuable contributions to the study of neutrino masses and lepton mixing. A Neutrino Factory is expected to improve the measurement accuracy of sin{sup 2}(2{theta}{sub 23}) and {Delta}m{sup 2}{sub 32} and provide measurements of sin{sup 2}(2{theta}{sub 13}) and the sign of {Delta}m{sup 2}{sub 32}. It may also be able to measure CP violation in the lepton sector.

  13. A study of methicillin - resistant staphylococcus aureus(MRSA) in a burn unit with repetitive - DNA - sequence- based PCR fingerprinting%烧伤病房耐甲氧西林金黄色葡萄球菌的DNA重复序列PCR研究

    Institute of Scientific and Technical Information of China (English)

    李洁; 徐秀华; 曾海涛

    2001-01-01

    in 22 of 41 (53.7%) patients, and 5 from the nasal vestibules. Moreover,among 19 medical staffs,MRSA strains were isolated from the hands of 9 persons, but not from the nasal vestibules. From the hands in 9 of 43 lay attendants and the nasal vestibules in 2 MRSA strains were found. Thirteen MRSA strains were isolated from 193 specimens from the surrounding items. It was indicated by repetitive DNA - sequence - based PCR analysis of the genome DNA of isolated MRSA strains that there existed homologous strains around the patients′ wounds, in the burn wounds, on the skin of medical staffs and lay attendants and also surrounding equipments. Conclusion (1) There was wide spread presence of MRSA homologous strains in the burn ward.(2) It was indicated by repetitive DNA - sequence - based PCR analysis of the genome DNA of isolated M RSA strains that there was cross infection among burn patients. The source of the infection of MRSA in burn ward was burn patients,and the route of the infection was hands of medical staffs and lay attendants. (3) MRSA is wide - spread. The contamination of the hands and the environment was potential risk factor of MRSA outbreak in the burn unit.

  14. Temporal-spatial distribution of non-point source pollution in a drinking water source reservoir watershed based on SWAT

    OpenAIRE

    Wang, M; Cheng, W.; Yu, B.-S.; Fang, Y.

    2015-01-01

    The conservation of drinking water source reservoirs has a close relationship between regional economic development and people’s livelihood. Research on the non-point pollution characteristics in its watershed is crucial for reservoir security. Tang Pu Reservoir watershed was selected as the study area. The non-point pollution model of Tang Pu Reservoir was established based on the SWAT (Soil and Water Assessment Tool) model. The model was adjusted to analyse the temporal-spatial distribution...

  15. Statistical and systematic uncertainties in pixel-based source reconstruction algorithms for gravitational lensing

    CERN Document Server

    Tagore, Amitpal

    2014-01-01

    Gravitational lens modeling of spatially resolved sources is a challenging inverse problem with many observational constraints and model parameters. We examine established pixel-based source reconstruction algorithms for de-lensing the source and constraining lens model parameters. Using test data for four canonical lens configurations, we explore statistical and systematic uncertainties associated with gridding, source regularisation, interpolation errors, noise, and telescope pointing. Specifically, we compare two gridding schemes in the source plane: a fully adaptive grid that follows the lens mapping but is irregular, and an adaptive Cartesian grid. We also consider regularisation schemes that minimise derivatives of the source (using two finite difference methods) and introduce a scheme that minimises deviations from an analytic source profile. Careful choice of gridding and regularisation can reduce "discreteness noise" in the $\\chi^2$ surface that is inherent in the pixel-based methodology. With a grid...

  16. Reassessment of the technical bases for estimating source terms. Final report

    International Nuclear Information System (INIS)

    This document describes a major advance in the technology for calculating source terms from postulated accidents at US light-water reactors. The improved technology consists of (1) an extensive data base from severe accident research programs initiated following the TMI accident, (2) a set of coupled and integrated computer codes (the Source Term Code Package), which models key aspects of fission product behavior under severe accident conditions, and (3) a number of detailed mechanistic codes that bridge the gap between the data base and the Source Term Code Package. The improved understanding of severe accident phenonmena has also allowed an identification of significant sources of uncertainty, which should be considered in estimating source terms. These sources of uncertainty are also described in this document. The current technology provides a significant improvement in evaluating source terms over that available at the time of the Reactor Safety Study (WASH-1400) and, because of this significance, the Nuclear Regulatory Commission staff is recommending its use

  17. Yb-fiber-laser-based, 1.8 W average power, picosecond ultraviolet source at 266 nm.

    Science.gov (United States)

    Chaitanya Kumar, S; Canals Casals, J; Sanchez Bautista, E; Devi, K; Ebrahim-Zadeh, M

    2015-05-15

    We report a compact, stable, high-power, picosecond ultraviolet (UV) source at 266 nm based on simple single-pass two-step fourth-harmonic generation (FHG) of a mode-locked Yb-fiber laser at 79.5 MHz in LiB3O5 (LBO) and β-BaB2O4. Using a 30-mm-long LBO crystal for single-pass second-harmonic generation, we achieve up to 9.1 W of average green power at 532 nm for 16.8 W of Yb-fiber power at a conversion efficiency of 54% in 16.2 ps pulses with a TEM00 spatial profile and passive power stability better than 0.5% rms over 16 h. The generated green radiation is then used for single-pass FHG into the UV, providing as much as 1.8 W of average power at 266 nm under the optimum focusing condition in the presence of spatial walk-off, at an overall FHG conversion efficiency of ∼11%. The generated UV output exhibits passive power stability better than 4.6% rms over 1.5 h and beam pointing stability better than 84 μrad over 1 h. The UV output beam has a circularity of >80% in high beam quality with the TEM00 mode profile. To the best of our knowledge, this is the first report of picosecond UV generation at 266 nm at megahertz repetition rates. PMID:26393749

  18. Dynamically reconfigurable directionality of plasmon-based single photon sources

    DEFF Research Database (Denmark)

    Chen, Yuntian; Lodahl, Peter; Koenderink, A. Femius

    2010-01-01

    We propose a plasmon-based reconfigurable antenna to controllably distribute emission from single quantum emitters in spatially separated channels. Our calculations show that crossed particle arrays can split the stream of photons from a single emitter into multiple narrow beams. We predict...... that beams can be switched on and off by switching host refractive index. The design method is based on engineering the dispersion relations of plasmon chains and is generally applicable to traveling wave antennas. Controllable photon delivery has potential applications in classical and quantum communication....

  19. Tomographs based on non-conventional radiation sources and methods

    International Nuclear Information System (INIS)

    Computer techniques for tomographic reconstruction of objects X-rayed with a compact plasma focus (PF) are presented. The implemented reconstruction algorithms are based on stochastic searching of solutions of Radon equation, using Genetic Algorithms and Monte Carlo methods. Numerical experiments using actual projections were performed concluding the feasibility of the application of both methods in tomographic reconstruction problem. (author)

  20. A preference-based multiple-source rough set model

    NARCIS (Netherlands)

    M.A. Khan; M. Banerjee

    2010-01-01

    We propose a generalization of Pawlak’s rough set model for the multi-agent situation, where information from an agent can be preferred over that of another agent of the system while deciding membership of objects. Notions of lower/upper approximations are given which depend on the knowledge base of

  1. Goal based mesh adaptivity for fixed source radiation transport calculations

    International Nuclear Information System (INIS)

    Highlights: ► Derives an anisotropic goal based error measure for shielding problems. ► Reduces the error in the detector response by optimizing the finite element mesh. ► Anisotropic adaptivity captures material interfaces using fewer elements than AMR. ► A new residual based on the numerical scheme chosen forms the error measure. ► The error measure also combines the forward and adjoint metrics in a novel way. - Abstract: In this paper, the application of goal based error measures for anisotropic adaptivity applied to shielding problems in which a detector is present is explored. Goal based adaptivity is important when the response of a detector is required to ensure that dose limits are adhered to. To achieve this, a dual (adjoint) problem is solved which solves the neutron transport equation in terms of the response variables, in this case the detector response. The methods presented can be applied to general finite element solvers, however, the derivation of the residuals are dependent on the underlying finite element scheme which is also discussed in this paper. Once error metrics for the forward and adjoint solutions have been formed they are combined using a novel approach. The two metrics are combined by forming the minimum ellipsoid that covers both the error metrics rather than taking the maximum ellipsoid that is contained within the metrics. Another novel approach used within this paper is the construction of the residual. The residual, used to form the goal based error metrics, is calculated from the subgrid scale correction which is inherent in the underlying spatial discretisation employed

  2. Carbon nanotube based field emission X-ray sources

    Science.gov (United States)

    Cheng, Yuan

    This dissertation describes the development of field emission (FE) x-ray sources with a carbon-nanotube (CNT) cathode. Field emission x-rays have advantages over conventional x-rays by replacing the thermionic cathode with a cold cathode so that electrons are emitted at room temperature and emission is voltage controllable. CNTs are found to be excellent electron emitters with low threshold fields and high current density which makes them ideal for generate field emission x-rays. Macroscopic CNT cold cathodes are prepared and the parameters to tune their field emission properties are studied: structure and morphology of CNT cathodes, temperature as well as electronic work function of CNT. Macroscopic CNT cathodes with optimized performance are chosen to build a high-resolution x-ray imaging system. The system can readily generate x-ray radiation with continuous variation of temporal resolution up to nanoseconds and spatial resolution down to 10 micron. Its potential applications for dynamic x-ray imaging and micro-computed tomography are also demonstrated. The performance characteristics of this compact and versatile system are promising for non-destructive testing and for non-invasive small-animal imaging for biomedical research.

  3. Physics data base for the beam plasma neutron source (BPNS)

    Energy Technology Data Exchange (ETDEWEB)

    Coensgen, F.H.; Casper, T.A.; Correll, D.L.; Damm, C.C.; Futch, A.H.; Molvik, A.W.

    1990-10-12

    A 14-MeV deuterium-tritium (D-T) neutron source for accelerated end-of-life testing of fusion reactor materials has been designed on the basis of a linear two-component collisional plasma system. An intense flux (up to 5 {times} 10{sup 18}/m{sup 2}{center dot}s) of 14-MeV neutrons is produced in a fully ionized high-density (n{sub e} {approx equal} 3 {times} 10{sup 21} m{sup {minus}3}) tritium target by transverse injection of 60 MW of neutral beam power. Power deposited in the target is removed by thermal electron conduction to large end chambers, where it is deposited in gaseous plasma collectors. We show in this paper that the major physics issues have now been experimentally demonstrated. These include magnetohydrodynamic (MHD) equilibrium and stability, microstability, startup, fueling, Spitzer electron thermal conductivity, and power deposition in a gaseous plasma collector. However, an integrated system has not been demonstrated. 28 refs., 8 figs., 2 tabs.

  4. Study on establishment of national information data base for the radiation sources in China

    International Nuclear Information System (INIS)

    China is a big developing country with large use of radioactive sources and nuclear technology. There are great number and different types of radioactive sources and radiation emitting apparatus. As a developing country, China still has a long way to go compared with advanced developed countries in the fields of radiation safety management and related technology. Up to now, some basic information are not clear, such as exact number, type, radiation character, purpose of using radiation sources and the owners of the radioactive sources and radiation emitting apparatus. And also, the information system and related data base has not been established yet. Another problem is that the Chinese experts do not fully master the incidents and accidents happened worldwide, so that the effective experience feedback can not be implemented. From preliminary survey there are 30000 - 50000 radioactive sources in China. Some people died or injured by radioactive accidents in the application of radioactive sources and nuclear technology in China. And some accidents such as loss control of radioactive sources caused radioactive contamination dispersion so that the radioactive materials contaminated environment in certain areas in the past. The Chinese government has paid great attention to the radiation safety in the development of radioactive sources and nuclear technology utilization. The radiation safety management and control on radioactive sources and nuclear technology utilization will be strengthened. In order to ensure the radiation safety and master the exact number of the radiation sources in China, we should investigate and integrate the basic information of radiation sources, including the spent radiation sources. The paper suggest to establish the information data base of radiation safety management on radioactive sources and nuclear technology utilization in China, based on the analysis of the present situation and problems in China. The paper also discusses the contents

  5. Repetitive pulse accelerator technology for light ion inertial confinement fusion

    International Nuclear Information System (INIS)

    This paper will overview the technologies being studied for a repetitively pulsed ICF accelerator. As presently conceived, power is supplied by rotating machinery providing 16 MJ in 1 ms. The generator output is transformed to 3 MV, then switched into a pulse compression system using laser triggered spark gaps. These must be synchronized to about 1 ns. Pulse compression is performed with saturable inductor switches, the output being 40 ns, 1.5 MV pulses. These are transformed to 30 MV in a self-magnetically insulated cavity adder structure. Space charge limited ion beams are drawn from anode plasmas with electron counter streaming being magnetically inhibited. The ions are ballistically focused into the entrances of guiding discharge channels for transport to the pellet. The status of component development from the prime power to the ion source will be reviewed

  6. Ablation Properties of the Carbon-Based Composites Used in Artificial Heat Source Under Fire Accident

    Institute of Scientific and Technical Information of China (English)

    TANG; Xian; HUANG; Jin-ming; ZHOU; Shao-jian; LUO; Zhi-fu

    2012-01-01

    <正>The ablation properties of the carbon-based composites used in artificial heat source under fire accident were investigated by the arc heater. In this work, we tested the carbon-based composites referring to Fig. 1. Their linear/mass ablation ratio and ablation morphologies were studied. The results showed that the carbon-based composites used in artificial heat source behaved well

  7. Combustion-based power source for Venus surface missions

    Science.gov (United States)

    Miller, Timothy F.; Paul, Michael V.; Oleson, Steven R.

    2016-10-01

    The National Research Council has identified in situ exploration of Venus as an important mission for the coming decade of NASA's exploration of our solar system (Squyers, 2013 [1]). Heavy cloud cover makes the use of solar photovoltaics extremely problematic for power generation for Venus surface missions. In this paper, we propose a class of planetary exploration missions (for use on Venus and elsewhere) in solar-deprived situations where photovoltaics cannot be used, batteries do not provide sufficient specific energy and mission duration, and nuclear systems may be too costly or complex to justify or simply unavailable. Metal-fueled, combustion-based powerplants have been demonstrated for application in the terrestrial undersea environment. Modified or extended versions of the undersea-based systems may be appropriate for these sunless missions. We describe systems carrying lithium fuel and sulfur-hexafluoride oxidizer that have the potential for many days of operation in the sunless craters of the moon. On Venus a system level specific energy of 240 to 370 We-hr/kg should be possible if the oxidizer is brought from earth. By using either lithium or a magnesium-based alloy fuel, it may be possible to operate a similar system with CO2 derived directly from the Venus atmosphere, thus providing an estimated system specific energy of 1100 We+PV-hr/kg (the subscript refers to both electrical and mechanical power), thereby providing mission durations that enable useful scientific investigation. The results of an analysis performed by the NASA Glenn COMPASS team describe a mission operating at 2.3 kWe+PV for 5 days (120 h), with less than 260 kg power/energy system mass total. This lander would be of a size and cost suitable for a New Frontiers class of mission.

  8. Compact THz radiation source based on photocathode RF gun

    Institute of Scientific and Technical Information of China (English)

    URAKAWA; JunJi

    2011-01-01

    Terahertz (THz) science and technology have already become the research highlight at present. In this paper, we put forward a proposal to generate THz radiation at tens of MW peak power. As a result of the ultrafast laser and the high accelerating field of photocathode RF gun, we can generate and accelerate an electron beam to several MeV, of which the bunch length is less than sub-ps. When the short electron bunches are injected into the wiggler, THz radiation based on Coherent Synchrotron Radiation could be achieved with tens of MW peak power. The whole THz FEL facility can be scaled to the size of a tabletop.

  9. Fiber MOPA based tunable source for terahertz spectroscopy

    International Nuclear Information System (INIS)

    We have developed a terahertz spectrometer based on difference frequency generation of beams from an ytterbium fiber master oscillator power amplifier (MOPA) system. The spectrometer has a resolution of ∼ 2 GHz. It can be tuned rapidly over several hundred GHz, and a wider frequency range can be covered (0.7–2.5 THz demonstrated) by swapping in alternate seed lasers and adjusting the alignment of the beams into the difference frequency generation (DFG) crystal. The system was constructed entirely from commercially available fiber and fiber components. We present some demonstration data on water vapor absorption lines

  10. Multi-wavelength fiber source based on double-pass superfluorescent fiber source and a reflection Mach-Zehnder filter

    Institute of Scientific and Technical Information of China (English)

    Wencai Huang; Hai Ming; Xiulin Wang; Huiying Xu

    2005-01-01

    A spectrum-sliced multi-wavelength fiber source (SS-MWFS) based on double-pass superfluorescent fiber source (SFS) with a reflection Mach-Zehnder filter (RMZF) as the reflected comb filter is demonstrated.With backward pumped configuration, MWFS with 50 wavelength channels of extinction ratio (ER) of 16.7 dB is obtained over the almost total C-band gain region. Total output power of the MWFS is 16.2 mW which shows that a power of about 0.3 mW of per channel is achieved. The SS-MWFS with forward pumped configuration is also discussed for comparing. The backward pumped configuration can provide a larger output power while only a little smaller ER than that of the forward pumped configuration.

  11. Progress of based on compact Marx generators high power microwave source%紧凑型Marx发生器高功率微波源研究进展

    Institute of Scientific and Technical Information of China (English)

    刘金亮; 樊旭亮; 白国强; 程新兵

    2012-01-01

    The compact Marx generators, which can operate at a certain repetition frequency with small size, light weight, and high energy efficiency, are widely used in narrowband, wideband and ultra-wideband high power microwave (HPM) sources. This type of HPM source based on compact Marx generators is a worldwide research focus in recent years, and is an important trend of development. The developments of this type of HPM source are described systemically in this paper. The output parameters and structural characteristics are reviewed, and the trends of development are discussed. This work provides reference and evidence for us to master the status of the HPM source based on compact Marx generators correctly and to explore its technical routes scientifically.%紧凑型Marx发生器不但体积小,重量轻,而且能量效率高,能以一定的重复频率运行,在窄带、宽带和超宽带高功率微波源中获得了广泛的应用.这种类型的高功率微波源是近几年来国内外的研究热点和重要发展方向.对国内外基于紧凑型Marx发生器的高功率微波源的研究进展进行了系统介绍,评述其输出参数和结构特点,并探讨其发展趋势,为正确把握基于紧凑型Marx发生器的高功率微波源的发展动态、科学探索其技术路线提供参考和依据.

  12. Small Area Model-Based Estimators Using Big Data Sources

    Directory of Open Access Journals (Sweden)

    Marchetti Stefano

    2015-06-01

    Full Text Available The timely, accurate monitoring of social indicators, such as poverty or inequality, on a finegrained spatial and temporal scale is a crucial tool for understanding social phenomena and policymaking, but poses a great challenge to official statistics. This article argues that an interdisciplinary approach, combining the body of statistical research in small area estimation with the body of research in social data mining based on Big Data, can provide novel means to tackle this problem successfully. Big Data derived from the digital crumbs that humans leave behind in their daily activities are in fact providing ever more accurate proxies of social life. Social data mining from these data, coupled with advanced model-based techniques for fine-grained estimates, have the potential to provide a novel microscope through which to view and understand social complexity. This article suggests three ways to use Big Data together with small area estimation techniques, and shows how Big Data has the potential to mirror aspects of well-being and other socioeconomic phenomena.

  13. Storytelling and Repetitive Narratives for Design Empathy

    DEFF Research Database (Denmark)

    Fritsch, Jonas; Judice, Andrea; Soini, Katja;

    2007-01-01

    Today it is widely established in design research that empathy is an important part of creating a true understanding of user experience as a resource for design. A typical challenge is how to transmit the feeling of empathy acquired by user studies to designers who have not participated in the user...... study. In this paper, we show how we attained an empathic understanding through storytelling and aroused empathy to others using repetitive narratives in an experimental presentation bringing forth factual, reflective and experiential aspects of the user information. Taking as a starting point our...... experiences with the design project Suomenlinna Seclusive, we conclude with the potential of using narratives for invoking design empathy....

  14. The repetitive component of the sunflower genome

    Directory of Open Access Journals (Sweden)

    T. Giordani

    2014-08-01

    Full Text Available The sunflower (Helianthus annuus and species belonging to the genus Helianthus are emerging as a model species and genus for a number of studies on genome evolution. In this review, we report on the repetitive component of the H. annuus genome at the biochemical, molecular, cytological, and genomic levels. Recent work on sunflower genome composition is described, with emphasis on different types of repeat sequences, especially LTR-retrotransposons, of which we report on isolation, characterisation, cytological localisation, transcription, dynamics of proliferation, and comparative analyses within the genus Helianthus.

  15. High repetition rate kickers for linear colliders

    International Nuclear Information System (INIS)

    It was shown in a previous paper that kickers with a high repetition rate can be designed by combining several cavities operating in a deflecting mode. In this paper we simplify this idea by showing that such kickers can be built also with one cavity or with an assembly of coupled cavities operating at several frequencies. We also demonstrate that this concept can be used for accelerating cavities. The electrical breakdown limit for such multimode accelerating cavities will be significantly higher than conventional single-mode cavities; therefore higher acceleration gradients, e.g., for linear colliders, can be achieved. 2 refs., 4 figs

  16. Problems in the fingerprints based polycyclic aromatic hydrocarbons source apportionment analysis and a practical solution.

    Science.gov (United States)

    Zou, Yonghong; Wang, Lixia; Christensen, Erik R

    2015-10-01

    This work intended to explain the challenges of the fingerprints based source apportionment method for polycyclic aromatic hydrocarbons (PAH) in the aquatic environment, and to illustrate a practical and robust solution. The PAH data detected in the sediment cores from the Illinois River provide the basis of this study. Principal component analysis (PCA) separates PAH compounds into two groups reflecting their possible airborne transport patterns; but it is not able to suggest specific sources. Not all positive matrix factorization (PMF) determined sources are distinguishable due to the variability of source fingerprints. However, they constitute useful suggestions for inputs for a Bayesian chemical mass balance (CMB) analysis. The Bayesian CMB analysis takes into account the measurement errors as well as the variations of source fingerprints, and provides a credible source apportionment. Major PAH sources for Illinois River sediments are traffic (35%), coke oven (24%), coal combustion (18%), and wood combustion (14%). PMID:26208321

  17. Characteristics of a Saturated 18.9 nm Tabletop Laser Operating at 5 Hz Repetition Rate

    Energy Technology Data Exchange (ETDEWEB)

    Larotonda, M A; Luther, B M; Wang, Y; Liu, Y; Alessi, D; Berrill, M; Dummer, A; Brizuela, F; Menoni, C S; Marconi, M; Shlyaptsev, V N; Dunn, J; Rocca, J J

    2005-01-10

    We report the characteristics of a saturated high repetition rate Ni-like Mo laser at 18.9 nm. This table-top soft x-ray laser was pumped at 5 Hz repetition rate by 8 ps, 1 J optical laser pulses impinging at grazing incidence into a pre-created Mo plasma. The variation of the laser output intensity as a function of the grazing incidence angle of the main pump beam is reported. The maximum laser intensity was observed for an angle of 20 degrees, at which we measured a small signal gain of 65 cm{sup -1} and a gain-length product gxl > 15. Spatial coherence measurements resulting from a Young's double slit interference experiment show the equivalent incoherent source diameter is about 11 {micro}m. The peak spectral brightness is estimated to be of the order of 1 x 10{sup 24} photons s{sup -1} mm{sup -2} mrad{sup -2} within 0.01% spectral bandwidth. This type of practical, small scale, high repetition soft x-ray laser is of interest for many applications. This acts to reduce the sensitivity of burst properties to metallicity. Only the first anomalous burst in one model produces nuclei as heavy as A = 100. For the present choice of nuclear physics and accretion rates, other bursts and models make chiefly nuclei with A {approx} 64. The amount of carbon remaining after hydrogen-helium bursts is typically {approx}< 1% by mass, and decreases further as the ashes are periodically heated by subsequent bursts. For M = 3.5 x 10{sup -10} M{sub {circle_dot}} yr{sup -1} and solar metallicity, bursts are ignited in a hydrogen-free helium layer. At the base of this layer, up to 90% of the helium has already burned to carbon prior to the unstable ignition of the helium shell. These helium-ignited bursts have (a) briefer, brighter light curves with shorter tails; (b) very rapid rise times (< 0.1 s); and (c) ashes lighter than the iron group.

  18. Query processing in distributed, taxonomy-based information sources

    CERN Document Server

    Meghini, Carlo; Coltella, Veronica; Analyti, Anastasia

    2011-01-01

    We address the problem of answering queries over a distributed information system, storing objects indexed by terms organized in a taxonomy. The taxonomy consists of subsumption relationships between negation-free DNF formulas on terms and negation-free conjunctions of terms. In the first part of the paper, we consider the centralized case, deriving a hypergraph-based algorithm that is efficient in data complexity. In the second part of the paper, we consider the distributed case, presenting alternative ways implementing the centralized algorithm. These ways descend from two basic criteria: direct vs. query re-writing evaluation, and centralized vs. distributed data or taxonomy allocation. Combinations of these criteria allow to cover a wide spectrum of architectures, ranging from client-server to peer-to-peer. We evaluate the performance of the various architectures by simulation on a network with O(10^4) nodes, and derive final results. An extensive review of the relevant literature is finally included.

  19. Accurate geolocation of rfi sources in smos imagery based on superresolution algorithms

    OpenAIRE

    Hyuk, Park; Camps Carmona, Adriano José; González Gambau, Veronica

    2014-01-01

    Accurate geolocation of SMOS RFI sources is very important for effectively switching-off the illegal emitter in the protected L-band. We present a novel approach for the geolocation of SMOS RFI sources, based on the Direction of Arrival (DOA) estimation techniques normally used in the sensor array. The MUSIC DOA estimation algorithm is tailored for SMOS RFI source detection. In the test results, the proposed MUSIC method shows improved performance in terms of angular/spatial resolution.

  20. Fuel-Cell Power Source Based on Onboard Rocket Propellants

    Science.gov (United States)

    Ganapathi, Gani; Narayan, Sri

    2010-01-01

    The use of onboard rocket propellants (dense liquids at room temperature) in place of conventional cryogenic fuel-cell reactants (hydrogen and oxygen) eliminates the mass penalties associated with cryocooling and boil-off. The high energy content and density of the rocket propellants will also require no additional chemical processing. For a 30-day mission on the Moon that requires a continuous 100 watts of power, the reactant mass and volume would be reduced by 15 and 50 percent, respectively, even without accounting for boiloff losses. The savings increase further with increasing transit times. A high-temperature, solid oxide, electrolyte-based fuel-cell configuration, that can rapidly combine rocket propellants - both monopropellant system with hydrazine and bi-propellant systems such as monomethyl hydrazine/ unsymmetrical dimethyl hydrazine (MMH/UDMH) and nitrogen tetroxide (NTO) to produce electrical energy - overcomes the severe drawbacks of earlier attempts in 1963-1967 of using fuel reforming and aqueous media. The electrical energy available from such a fuel cell operating at 60-percent efficiency is estimated to be 1,500 Wh/kg of reactants. The proposed use of zirconia-based oxide electrolyte at 800-1,000 C will permit continuous operation, very high power densities, and substantially increased efficiency of conversion over any of the earlier attempts. The solid oxide fuel cell is also tolerant to a wide range of environmental temperatures. Such a system is built for easy refueling for exploration missions and for the ability to turn on after several years of transit. Specific examples of future missions are in-situ landers on Europa and Titan that will face extreme radiation and temperature environments, flyby missions to Saturn, and landed missions on the Moon with 14 day/night cycles.

  1. A method for MREIT-based source imaging: simulation studies

    Science.gov (United States)

    Song, Yizhuang; Jeong, Woo Chul; Woo, Eung Je; Seo, Jin Keun

    2016-08-01

    This paper aims to provide a method for using magnetic resonance electrical impedance tomography (MREIT) to visualize local conductivity changes associated with evoked neuronal activities in the brain. MREIT is an MRI-based technique for conductivity mapping by probing the magnetic flux density induced by an externally injected current through surface electrodes. Since local conductivity changes resulting from evoked neural activities are very small (less than a few %), a major challenge is to acquire exogenous magnetic flux density data exceeding a certain noise level. Noting that the signal-to-noise ratio is proportional to the square root of the number of averages, it is important to reduce the data acquisition time to get more averages within a given total data collection time. The proposed method uses a sub-sampled k-space data set in the phase-encoding direction to significantly reduce the data acquisition time. Since the sub-sampled data violates the Nyquist criteria, we only get a nonlinearly wrapped version of the exogenous magnetic flux density data, which is insufficient for conductivity imaging. Taking advantage of the sparseness of the conductivity change, the proposed method detects local conductivity changes by estimating the time-change of the Laplacian of the nonlinearly wrapped data.

  2. Taurine supplemented plant protein based diets with alternative lipid sources for juvenile sea bream, sparus aurata

    Science.gov (United States)

    Two lipid sources were evaluated as fish oil replacements in fishmeal free, plant protein based diets for juvenile gilthead sea bream, Sparus aurata. A twelve week feeding study was undertaken to examine the performance of fish fed the diets with different sources of essential fatty acids (canola o...

  3. Development of Management System for Regional Pollution Source Based on SuperMap Objects

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Based on the integration of C#.net and SuperMap Objects(tool software of component GIS),the management system of regional pollution source is developed.It mainly includes the demand analysis of system,function design,database construction,program design and concrete realization in the management aspect of pollution source.

  4. Improving repeatability of land seismic data using virtual source approach based on multidimensional deconvolution

    NARCIS (Netherlands)

    Alexandrov, D.; Van der Neut, J.R.; Bakulin, A.; Kashtan, B.

    2015-01-01

    We present a new redatuming workflow developed for improving the repeatability of seismic data and designed specifically to account for changes in the source signatures or variations in downgoing fields in general. The new approach is based on the virtual source method with the same potential for re

  5. The Research of Heterogeneous Data Source Integration Method Based on Ontology

    Institute of Scientific and Technical Information of China (English)

    Lou,Yabin; Tao,Fengmei; Ma,Yuan

    2005-01-01

    This paper provides an integration scheme of heterogeneous data source based on ontology, and this scheme settles basically syntactic and semantic heterogeneity in heterogeneous data sources; meanwhile, it provides an effective technology measure for the interior information of enterprises to be shared in time accurately.

  6. Microdischarge Array Flexible Light Source for High-Efficiency Irradiation of Spaced-Based Crops Project

    Data.gov (United States)

    National Aeronautics and Space Administration — It is desirable to develop a high-efficiency lighting source for large-area irradiation of space-based crops. The key requirements for such a system include high...

  7. Photoacoustic Techniques for Trace Gas Sensing Based on Semiconductor Laser Sources

    Directory of Open Access Journals (Sweden)

    Vincenzo Spagnolo

    2009-12-01

    Full Text Available The paper provides an overview on the use of photoacoustic sensors based on semiconductor laser sources for the detection of trace gases. We review the results obtained using standard, differential and quartz enhanced photoacoustic techniques.

  8. High-Efficiency Nitride-Base Photonic Crystal Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    James Speck; Evelyn Hu; Claude Weisbuch; Yong-Seok Choi; Kelly McGroddy; Gregor Koblmuller; Elison Matioli; Elizabeth Rangel; Fabian Rol; Dobri Simeonov

    2010-01-31

    The research activities performed in the framework of this project represent a major breakthrough in the demonstration of Photonic Crystals (PhC) as a competitive technology for LEDs with high light extraction efficiency. The goals of the project were to explore the viable approaches to manufacturability of PhC LEDS through proven standard industrial processes, establish the limits of light extraction by various concepts of PhC LEDs, and determine the possible advantages of PhC LEDs over current and forthcoming LED extraction concepts. We have developed three very different geometries for PhC light extraction in LEDs. In addition, we have demonstrated reliable methods for their in-depth analysis allowing the extraction of important parameters such as light extraction efficiency, modal extraction length, directionality, internal and external quantum efficiency. The information gained allows better understanding of the physical processes and the effect of the design parameters on the light directionality and extraction efficiency. As a result, we produced LEDs with controllable emission directionality and a state of the art extraction efficiency that goes up to 94%. Those devices are based on embedded air-gap PhC - a novel technology concept developed in the framework of this project. They rely on a simple and planar fabrication process that is very interesting for industrial implementation due to its robustness and scalability. In fact, besides the additional patterning and regrowth steps, the process is identical as that for standard industrially used p-side-up LEDs. The final devices exhibit the same good electrical characteristics and high process yield as a series of test standard LEDs obtained in comparable conditions. Finally, the technology of embedded air-gap patterns (PhC) has significant potential in other related fields such as: increasing the optical mode interaction with the active region in semiconductor lasers; increasing the coupling of the incident

  9. Synchronization System for Next Generation Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Zavriyev, Anton

    2014-03-27

    An alternative synchronization technique – one that would allow explicit control of the pulse train including its repetition rate and delay is clearly desired. We propose such a scheme. Our method is based on optical interferometry and permits synchronization of the pulse trains generated by two independent mode-locked lasers. As the next generation x-ray sources will be driven by a clock signal derived from a mode-locked optical source, our technique will provide a way to synchronize x-ray probe with the optical pump pulses.

  10. Techniques and Application of Electron Spectroscopy Based on Novel X-ray Sources

    OpenAIRE

    Plogmaker, Stefan

    2012-01-01

    The curiosity of researchers to find novel characteristics and properties of matter constantly pushes for the development of instrumentation based on X-radiation. I present in this thesis techniques for electron spectroscopy based on developments of X-ray sources both in time structure and energy. One part describes a laser driven High-Harmonic Generation source and the application of an off-plane grating monochromator with additional beamlines and spectrometers. In initial experiments, the s...

  11. Open-Source web-based geographical information system for health exposure assessment

    Directory of Open Access Journals (Sweden)

    Evans Barry

    2012-01-01

    Full Text Available Abstract This paper presents the design and development of an open source web-based Geographical Information System allowing users to visualise, customise and interact with spatial data within their web browser. The developed application shows that by using solely Open Source software it was possible to develop a customisable web based GIS application that provides functions necessary to convey health and environmental data to experts and non-experts alike without the requirement of proprietary software.

  12. Open-Source web-based Geographical Information System for health exposure assessment.

    Science.gov (United States)

    Evans, Barry; Sabel, Clive E

    2012-01-01

    This paper presents the design and development of an open source web-based Geographical Information System allowing users to visualise, customise and interact with spatial data within their web browser. The developed application shows that by using solely Open Source software it was possible to develop a customisable web based GIS application that provides functions necessary to convey health and environmental data to experts and non-experts alike without the requirement of proprietary software.

  13. Identifying non-point source critical source areas based on multi-factors at a basin scale with SWAT

    Science.gov (United States)

    Liu, Ruimin; Xu, Fei; Zhang, Peipei; Yu, Wenwen; Men, Cong

    2016-02-01

    The identification of critical source areas (CSAs) is a precondition for non-point source (NPS) pollution control at a basin scale, especially in areas with limited resources. Based on the Soil and Water Assessment Tool (SWAT), nutrient loads coupled with population density and water quality requirements are regarded as multi-factors for CSAs identification in Xiangxi river watershed, the first tributary of the Yangtze River. The results based on the calibrated model found that the subbasins heavily and seriously polluted by nutrient loads were different from the subbasins identified as CSAs, demonstrating integrating socio-economic factors like population density and water quality requirements to identify CSAs is of much necessity. The CSAs occupied 19.7% of the total subbasins, and accounted for 53% total nitrogen loads, 54% total phosphorus loads and 36% of the total population. Considering the model calibration and validation will take a long time as well as data deficiency in some subbasins, the influence of uncalibrated SWAT on CSAs identifications was discussed. The comparative results between CSAs identification with calibrated and uncalibrated SWAT model revealed that model calibration had little effect on nutrients distribution and CSAs locations in the study area. Uncalibrated SWAT model may be applied when the research objective is less related to model calibration. The results will be greatly effective for CSAs identification and NPS pollution control at a basin scale.

  14. Current Source Converter Based Multi-terminal DC Wind Energy Conversion System

    Institute of Scientific and Technical Information of China (English)

    Shixiong FAN; Guangyi LIU; Zhanyong YANG; Weiwei MA; Barry W.WILLIAMS

    2013-01-01

    A current source converter based multi-terminal direct current (DC) wind energy conversion system (WECS) is proposed.The current source DC/DC converter is adopted to connect a wind turbine to an inverter with maximum power point control.Each turbine is associated with a DC source by parallel-connected to a common DC link.After DC power collection,a current source inverter (CSI) using gate turn-off components is used for the grid connection due to its flexible reactive power control and short circuit protection capabilities.For such a parallel connection configuration,the CSI operates in an input voltage control mode,which maintains the DC link voltage constant.The dynamic responses of combined mechanical and electrical systems are investigated with three different operation cases.Simulation and experimental results demonstrate the feasibility and stability of the current source DC/DC converter based multi-terminal DC WECS.

  15. ESTIMATION OF THE NUMBER OF CORRELATED SOURCES WITH COMMON FREQUENCIES BASED ON POWER SPECTRAL DENSITY

    Institute of Scientific and Technical Information of China (English)

    LI Ning; SHI Tielin

    2007-01-01

    Blind source Separation and estimation of the number of sources usually demand that the number of sensors should be greater than or equal to that of the sources, which, however, is very difficult to satisfy for the complex Systems. A new estimating method based on power spectral density (PSD) is presented. When the relation between the number of sensors and that of sources is unknown, the PSD matrix is first obtained by the ratio of PSD of the observation signals, and then the bound of the number of correlated sources with common frequencies can be estimated by comparing every column vector of PSD matrix. The effectiveness of the proposed method is verified by theoretical analysis and experiments, and the influence of noise on the estimation of number of source is simulated.

  16. Real-time tunability of chip-based light source enabled by microfluidic mixing

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Rasmussen, Torben; Balslev, Søren;

    2006-01-01

    We demonstrate real-time tunability of a chip-based liquid light source enabled by microfluidic mixing. The mixer and light source are fabricated in SU-8 which is suitable for integration in SU-8-based laboratory-on-a-chip microsystems. The tunability of the light source is achieved by changing...... the concentration of rhodamine 6G dye inside two integrated vertical resonators, since both the refractive index and the gain profile are influenced by the dye concentration. The effect on the refractive index and the gain profile of rhodamine 6G in ethanol is investigated and the continuous tuning of the laser...

  17. Exact and conceptual repetition dissociate conceptual memory tests: problems for transfer appropriate processing theory.

    Science.gov (United States)

    McDermott, K B; Roediger, H L

    1996-03-01

    Three experiments examined whether a conceptual implicit memory test (specifically, category instance generation) would exhibit repetition effects similar to those found in free recall. The transfer appropriate processing account of dissociations among memory tests led us to predict that the tests would show parallel effects; this prediction was based upon the theory's assumption that conceptual tests will behave similarly as a function of various independent variables. In Experiment 1, conceptual repetition (i.e., following a target word [e.g., puzzles] with an associate [e.g., jigsaw]) did not enhance priming on the instance generation test relative to the condition of simply presenting the target word once, although this manipulation did affect free recall. In Experiment 2, conceptual repetition was achieved by following a picture with its corresponding word (or vice versa). In this case, there was an effect of conceptual repetition on free recall but no reliable effect on category instance generation or category cued recall. In addition, we obtained a picture superiority effect in free recall but not in category instance generation. In the third experiment, when the same study sequence was used as in Experiment 1, but with instructions that encouraged relational processing, priming on the category instance generation task was enhanced by conceptual repetition. Results demonstrate that conceptual memory tests can be dissociated and present problems for Roediger's (1990) transfer appropriate processing account of dissociations between explicit and implicit tests. PMID:8653098

  18. TYPES OF REPETITIONS IN TEXTS MANSI CHILDREN’S FOLKLORE

    OpenAIRE

    Kumaeva Maria Vladimirovna

    2012-01-01

    The article discusses the various types of repetitions in the text Mansi children's folklore, in such genres as lullabies, tales, riddles. A characteristic of the individual types of repeats and the functions they perform in the texts. Numerous repetitions that occur in the texts of folklore, are compositional and stylistic value. We have seen reruns of stylistic values. The aim of this work is the identification and classification of types of repetition in the text children's folklore - lull...

  19. An incentive-based source separation model for sustainable municipal solid waste management in China.

    Science.gov (United States)

    Xu, Wanying; Zhou, Chuanbin; Lan, Yajun; Jin, Jiasheng; Cao, Aixin

    2015-05-01

    Municipal solid waste (MSW) management (MSWM) is most important and challenging in large urban communities. Sound community-based waste management systems normally include waste reduction and material recycling elements, often entailing the separation of recyclable materials by the residents. To increase the efficiency of source separation and recycling, an incentive-based source separation model was designed and this model was tested in 76 households in Guiyang, a city of almost three million people in southwest China. This model embraced the concepts of rewarding households for sorting organic waste, government funds for waste reduction, and introducing small recycling enterprises for promoting source separation. Results show that after one year of operation, the waste reduction rate was 87.3%, and the comprehensive net benefit under the incentive-based source separation model increased by 18.3 CNY tonne(-1) (2.4 Euros tonne(-1)), compared to that under the normal model. The stakeholder analysis (SA) shows that the centralized MSW disposal enterprises had minimum interest and may oppose the start-up of a new recycling system, while small recycling enterprises had a primary interest in promoting the incentive-based source separation model, but they had the least ability to make any change to the current recycling system. The strategies for promoting this incentive-based source separation model are also discussed in this study. PMID:25819930

  20. Studies of the uncanny: the repetition factor

    Directory of Open Access Journals (Sweden)

    Julia Teitelroit Martins

    2011-06-01

    Full Text Available Freud’s essay The Uncanny (Das Unheimliche offers many indications for the comprehension of an aesthetics of the uncanny which deserve to be explored. Nonetheless, a concept traverses it from beginning to end: the return – which enables its reading under the light of Beyond the pleasure principle, written along the same span of time. Emphasis is given to the uncanny in the sense of repetition of the different – a paradox in terms, like the strangely familiar uncanny. In order to test the validity of an aesthetic reading under this perspective, follows an analysis of the brief short story “A terceira margem do rio” (“The third margin of the river”, by Guimarães Rosa.

  1. Context and Repetition in Word Learning

    Directory of Open Access Journals (Sweden)

    Jessica S Horst

    2013-04-01

    Full Text Available Young children learn words from a variety of situations, including shared storybook reading. A recent study by Horst et al., (2011 demonstrates that children learned more new words during shared storybook reading if they were read the same stories repeatedly than if they were read different stories that had the same number of target words. The current paper reviews this study and further examines the effect of contextual repetition on children’s word learning in both shared storybook reading and other situations, including fast mapping by mutual exclusivity. The studies reviewed here suggest that the same cognitive mechanisms support word learning in a variety of situations. Both practical considerations for experimental design and directions for future research are discussed.

  2. A review of neuroimaging findings in repetitive brain trauma.

    Science.gov (United States)

    Koerte, Inga K; Lin, Alexander P; Willems, Anna; Muehlmann, Marc; Hufschmidt, Jakob; Coleman, Michael J; Green, Isobel; Liao, Huijun; Tate, David F; Wilde, Elisabeth A; Pasternak, Ofer; Bouix, Sylvain; Rathi, Yogesh; Bigler, Erin D; Stern, Robert A; Shenton, Martha E

    2015-05-01

    Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease confirmed at postmortem. Those at highest risk are professional athletes who participate in contact sports and military personnel who are exposed to repetitive blast events. All neuropathologically confirmed CTE cases, to date, have had a history of repetitive head impacts. This suggests that repetitive head impacts may be necessary for the initiation of the pathogenetic cascade that, in some cases, leads to CTE. Importantly, while all CTE appears to result from repetitive brain trauma, not all repetitive brain trauma results in CTE. Magnetic resonance imaging has great potential for understanding better the underlying mechanisms of repetitive brain trauma. In this review, we provide an overview of advanced imaging techniques currently used to investigate brain anomalies. We also provide an overview of neuroimaging findings in those exposed to repetitive head impacts in the acute/subacute and chronic phase of injury and in more neurodegenerative phases of injury, as well as in military personnel exposed to repetitive head impacts. Finally, we discuss future directions for research that will likely lead to a better understanding of the underlying mechanisms separating those who recover from repetitive brain trauma vs. those who go on to develop CTE.

  3. FEMA Hazard Mitigation Assistance Repetitive Flood Claims (RFC) Data

    Data.gov (United States)

    Department of Homeland Security — This dataset contains closed and obligated projects funded under the following Hazard Mitigation Assistance (HMA) grant programs: Repetitive Flood Claims (RFC). The...

  4. The use of repetition suppression paradigms in developmental cognitive neuroscience.

    Science.gov (United States)

    Nordt, Marisa; Hoehl, Stefanie; Weigelt, Sarah

    2016-07-01

    Repetition suppression paradigms allow a more detailed look at brain functioning than classical paradigms and have been applied vigorously in adult cognitive neuroscience. These paradigms are well suited for studies in the field of developmental cognitive neuroscience as they can be applied without collecting a behavioral response and across all age groups. Furthermore, repetition suppression paradigms can be employed in various neuroscience techniques, such as functional magnetic resonance imaging (fMRI), functional near-infrared spectroscopy (fNIRS), electroencephalography (EEG) and magnetoencephalography (MEG). In the present article we review studies using repetition suppression paradigms in developmental cognitive neuroscience covering the age range from infancy to adolescence. Our first goal is to point out characteristics of developmental repetition suppression effects. In doing so, we discuss the relationship of the direction of repetition effects (suppression vs enhancement) with developmental factors, and address the question how the direction of repetition effects might be related to looking-time effects in behavioral infant paradigms, the most prominently used behavioral measure in infant research. To highlight the potential of repetition suppression paradigms, our second goal is to provide an overview on the insights recently obtained by applying repetition paradigms in neurodevelopmental studies, including research on children with autism spectrum disorders (ASDs). We conclude that repetition suppression paradigms are valuable tools for investigating neurodevelopmental processes, while at the same time we highlight the necessity for further studies that disentangle methodological and developmental factors. PMID:27161033

  5. FEMA Hazard Mitigation Assistance Severe Repetitive Loss (SRL) Data

    Data.gov (United States)

    Department of Homeland Security — This dataset contains closed and obligated projects funded under the following Hazard Mitigation Assistance (HMA) grant programs: Severe Repetitive Loss (SRL). The...

  6. Detecting black bear source-sink dynamics using individual-based genetic graphs.

    Science.gov (United States)

    Draheim, Hope M; Moore, Jennifer A; Etter, Dwayne; Winterstein, Scott R; Scribner, Kim T

    2016-07-27

    Source-sink dynamics affects population connectivity, spatial genetic structure and population viability for many species. We introduce a novel approach that uses individual-based genetic graphs to identify source-sink areas within a continuously distributed population of black bears (Ursus americanus) in the northern lower peninsula (NLP) of Michigan, USA. Black bear harvest samples (n = 569, from 2002, 2006 and 2010) were genotyped at 12 microsatellite loci and locations were compared across years to identify areas of consistent occupancy over time. We compared graph metrics estimated for a genetic model with metrics from 10 ecological models to identify ecological factors that were associated with sources and sinks. We identified 62 source nodes, 16 of which represent important source areas (net flux > 0.7) and 79 sink nodes. Source strength was significantly correlated with bear local harvest density (a proxy for bear density) and habitat suitability. Additionally, resampling simulations showed our approach is robust to potential sampling bias from uneven sample dispersion. Findings demonstrate black bears in the NLP exhibit asymmetric gene flow, and individual-based genetic graphs can characterize source-sink dynamics in continuously distributed species in the absence of discrete habitat patches. Our findings warrant consideration of undetected source-sink dynamics and their implications on harvest management of game species. PMID:27440668

  7. Thinking about online sources: Exploring students' epistemic cognition in internet-based chemistry learning

    Science.gov (United States)

    Dai, Ting

    This dissertation investigated the relation between epistemic cognition---epistemic aims and source beliefs---and learning outcome in an Internet--based research context. Based on a framework of epistemic cognition (Chinn, Buckland, & Samarapungavan, 2011), a context--specific epistemic aims and source beliefs questionnaire (CEASBQ) was developed and administered to 354 students from college--level introductory chemistry courses. A series of multitrait--multimethod model comparisons provided evidence for construct convergent and discriminant validity for three epistemic aims--- true beliefs, justified beliefs, explanatory connection, which were all distinguished from, yet correlated with, mastery goals. Students' epistemic aims were specific to the chemistry topics in research. Multidimensional scaling results indicated that students' source evaluation was based on two dimensions--- professional expertise and first--hand knowledge, suggesting a multidimensional structure of source beliefs. Most importantly, online learning outcome was found to be significantly associated with two epistemic aims---justified beliefs and explanatory connection: The more students sought justifications in the online research, the lower they tended to score on the learning outcome measure, whereas the more students sought explanatory connections between information, the higher they scored on the outcome measure. There was a significant but small positive association between source beliefs and learning outcome. The influences of epistemic aims and source beliefs on learning outcome were found to be above and beyond the effects of a number of covariates, including prior knowledge and perceived ability with online sources.

  8. Development of a 16 kHz repetition rate, 110 W average power copper HyBrID laser

    Indian Academy of Sciences (India)

    R Biswal; P K Agrawal; G K Mishra; S V Nakhe; S K Dixit; J K Mittal

    2010-11-01

    This paper presents the design and performance analysis of an indigenously developed 110 W average output power copper HyBrID laser operating at 16 kHz pulse repetition rate. The laser active medium was confined within a fused silica tube of ∼ 6 cm diameter and ∼ 200 cm active length. An in-house developed high-power (∼ 10 kW) solid-state pulser was used as the electrical excitation source. A simple estimation of deposited electrical power, at the laser head, was carried out and based on it, the laser tube efficiency was found to be 2.9% at 70 W and 2.2% at 110 W laser power levels.

  9. Temporal-spatial distribution of non-point source pollution in a drinking water source reservoir watershed based on SWAT

    Science.gov (United States)

    Wang, M.; Cheng, W.; Yu, B.-S.; Fang, Y.

    2015-05-01

    The conservation of drinking water source reservoirs has a close relationship between regional economic development and people's livelihood. Research on the non-point pollution characteristics in its watershed is crucial for reservoir security. Tang Pu Reservoir watershed was selected as the study area. The non-point pollution model of Tang Pu Reservoir was established based on the SWAT (Soil and Water Assessment Tool) model. The model was adjusted to analyse the temporal-spatial distribution patterns of total nitrogen (TN) and total phosphorus (TP). The results showed that the loss of TN and TP in the reservoir watershed were related to precipitation in flood season. And the annual changes showed an "M" shape. It was found that the contribution of loss of TN and TP accounted for 84.5% and 85.3% in high flow years, and for 70.3% and 69.7% in low flow years, respectively. The contributions in normal flow years were 62.9% and 63.3%, respectively. The TN and TP mainly arise from Wangtan town, Gulai town, and Wangyuan town, etc. In addition, it was found that the source of TN and TP showed consistency in space.

  10. Could the DiversiLab® semi-automated repetitive-sequence-based PCR be an acceptable technique for typing isolates of Pseudomonas aeruginosa? An answer from our experience and a review of the literature.

    Science.gov (United States)

    Brossier, Florence; Micaelo, Maïté; Luyt, Charles-Edouard; Lu, Qin; Chastre, Jean; Arbelot, Charlotte; Trouillet, Jean-Louis; Combes, Alain; Rouby, Jean-Jacques; Jarlier, Vincent; Aubry, Alexandra

    2015-12-01

    Recently the DiversiLab® (DL) system (bioMérieux) was developed as an automated platform that uses repetitive element polymerase chain reaction (rep-PCR) technology for standardized, reproducible DNA fingerprinting of bacteria. The purpose of this study was to evaluate the usefulness of DL rep-PCR for typing Pseudomonas aeruginosa isolates. The performance of DL rep-PCR was compared with that of pulsed-field gel electrophoresis (PFGE) in a prospective multicenter study of patients with ventilator-associated pneumonia due to P. aeruginosa, conducted in 3 intensive care units over a 31-month period. In total, 203 P. aeruginosa isolates from 66 patients, from whom at least 2 consecutive respiratory samples each were collected more than 48 h apart, were typed using DL rep-PCR. Forty isolates (corresponding to 20 patients) were also typed using PFGE of SpeI-digested DNA. The typeability was 100% with DL rep-PCR and 95% with PFGE. The discriminatory power was close for DL rep-PCR and for PFGE (Simpson's diversity indices of 0.901 and 0.947, respectively). Insufficient agreement between DL rep-PCR and PFGE typing results was observed for the 40 selected isolates (adjusted Rand coefficient of 0.419), mostly due to isolates of the same DL rep-PCR type but of different PFGE types (adjusted Wallace coefficients of 0.306 for DL rep-PCR with PFGE, and of 0.667 for PFGE with DL rep-PCR). Considered together with published data, DL rep-PCR results should be interpreted with caution for the investigation of outbreaks caused by P. aeruginosa and evaluated in conjunction with epidemiological data.

  11. 基于弓形虫529-bp重复序列巢式PCR诊断方法的建立%Establishment of nested PCR based on 529-bp repetitive sequence for diagnosis of Toxoplasma gondii

    Institute of Scientific and Technical Information of China (English)

    张莹光; 曹利利; 徐丹; 宋鑫帅; 魏峰; 许越; 王巍; 杨桂连; 刘全

    2013-01-01

    The nested PCR primers were designed according to GenBank published 529-bp repetitive DNA sequence(AF146527) in Toxoplasma gondii ,we have established the nested PCR. The product of the nested PCR was about 427 bp and its sensitivity was 100 times than that of conventional PCR, which could detect the genomic DNA as low as 0. 1 pg. Detection of Leishmania tarentolae, Cryptosporidium parvum and Echinococcus granulosus genome DNA by nested PCR had no fragment. The diagnosis coincidence rate is 100%. The nested PCR method is dependable for diagnosis of Toxoplasma gondii.%根据GenBank已发表的弓形虫529-bp重复序列(AF146527)设计巢式PCR引物,建立巢式PCR检测方法.结果表明,该方法能扩增出427 bp的片段,敏感性试验表明该方法可以检测出0.1 pg的弓形虫基因组DNA,敏感性是常规PCR的100倍.巢式PCR方法对蜥蜴利什曼原虫、隐孢子虫、细粒棘球绦虫基因组扩增无条带,特异性强.样品检测符合率达100%.巢式PCR方法的建立为弓形虫病的诊断及流行病学调查提供技术支持.

  12. [Nitrogen non-point source pollution identification based on ArcSWAT in Changle River].

    Science.gov (United States)

    Deng, Ou-Ping; Sun, Si-Yang; Lü, Jun

    2013-04-01

    The ArcSWAT (Soil and Water Assessment Tool) model was adopted for Non-point source (NPS) nitrogen pollution modeling and nitrogen source apportionment for the Changle River watershed, a typical agricultural watershed in Southeast China. Water quality and hydrological parameters were monitored, and the watershed natural conditions (including soil, climate, land use, etc) and pollution sources information were also investigated and collected for SWAT database. The ArcSWAT model was established in the Changle River after the calibrating and validating procedures of the model parameters. Based on the validated SWAT model, the contributions of different nitrogen sources to river TN loading were quantified, and spatial-temporal distributions of NPS nitrogen export to rivers were addressed. The results showed that in the Changle River watershed, Nitrogen fertilizer, nitrogen air deposition and nitrogen soil pool were the prominent pollution sources, which contributed 35%, 32% and 25% to the river TN loading, respectively. There were spatial-temporal variations in the critical sources for NPS TN export to the river. Natural sources, such as soil nitrogen pool and atmospheric nitrogen deposition, should be targeted as the critical sources for river TN pollution during the rainy seasons. Chemical nitrogen fertilizer application should be targeted as the critical sources for river TN pollution during the crop growing season. Chemical nitrogen fertilizer application, soil nitrogen pool and atmospheric nitrogen deposition were the main sources for TN exported from the garden plot, forest and residential land, respectively. However, they were the main sources for TN exported both from the upland and paddy field. These results revealed that NPS pollution controlling rules should focus on the spatio-temporal distribution of NPS pollution sources. PMID:23798104

  13. A high-efficiency electrically-pumped single-photon source based on a photonics nanowire

    DEFF Research Database (Denmark)

    Gregersen, Niels; Nielsen, Torben Roland; Mørk, Jesper;

    An electrically-pumped single-photon source design with a predicted efficiency of 89% is proposed. The design is based on a quantum dot embedded in a photonic nanowire with tailored ends and optimized contact electrodes. Unlike cavity-based approaches, the photonic nanowire features broadband...

  14. A Monte-Carlo-Based Network Method for Source Positioning in Bioluminescence Tomography

    OpenAIRE

    Zhun Xu; Xiaolei Song; Xiaomeng Zhang; Jing Bai

    2007-01-01

    We present an approach based on the improved Levenberg Marquardt (LM) algorithm of backpropagation (BP) neural network to estimate the light source position in bioluminescent imaging. For solving the forward problem, the table-based random sampling algorithm (TBRS), a fast Monte Carlo simulation method ...

  15. Very Efficient Single-Photon Sources Based on Quantum Dots in Photonic Wires

    DEFF Research Database (Denmark)

    Gerard, Jean-Michel; Claudon, Julien; Bleuse, Joel;

    2014-01-01

    We review the recent development of high efficiency single photon sources based on a single quantum dot in a photonic wire. Unlike cavity-based devices, very pure single photon emission and efficiencies exceeding 0.7 photon per pulse are jointly demonstrated under non-resonant pumping conditions...... optical properties of "one-dimensional atoms"....

  16. The precipitation driven correlation based mapping method (PCM) for identifying the critical source areas of non-point source pollution

    Science.gov (United States)

    Huang, Jinhui Jeanne; Lin, Xiaojuan; Wang, Jianhua; Wang, Hao

    2015-05-01

    Critical source areas (CSAs) are the areas that are relatively more erosion-prone and contribute significantly more pollutants per unit area. They have been widely recognized as optimal locations for the control of non-point source (NPS) pollution. Modeling approach has been frequently used to identify the CSAs of NPS pollution on a basin scale. In previous studies, CSAs were identified based on the simulated average annual nutrient yields for the simulation period at the levels of sub-basin or hydrologic response unit (HRU). However, this method did not consider the impact of uneven spatial distribution of precipitation, which is considered to be the driven force of NPS pollution. In many cases, due to limited length of qualified monitoring data collected, the simulation period may not cover a full spectrum of the precipitation characteristics so that some potential CSAs may be missed. In the present study, the precipitation driven correlation based mapping method (PCM) was proposed, which can reduce the impact of uncertain spatial-temporal distribution of precipitation and identify the CSAs of NPS pollution with a better coverage. This method was applied to the Zhang River Basin, a watershed in North China that occupies an area of 18,072 km2. The SWAT (Soil and Water Assessment Tool) was used for simulation purposes. By using PCM, the maps of CSAs for controlling total nitrogen (TN) and total phosphorus (TP) were produced. This study has found that the monthly precipitation is highly correlated with the TN and TP yields. It was observed that TN yields have slightly higher correlation value with the precipitation than TP yields. Hence, the precipitation has more impacts on TN yields than TP yields. The impact is more substantial in urban areas than other areas.

  17. Repetitive Bunches from RF-Photo Gun Radiate Coherently

    CERN Document Server

    Van der Geer, C A J; Van der Geer, S B

    2004-01-01

    We consider to feed the laser wake field accelerator of the alpha-X project by a train of low charge pancake electron bunches to reduce undesired expansion due to space-charge forces. To this purpose the photo excitation laser of the rf-injector is split into a train of sub-pulses, such that each of the produced electron bunches falls into a successive ponderomotive well of the plasma accelerator. This way the total accelerated charge is not reduced. The repetitive photo gun can be tested, at low energy, by connecting it directly to the undulator and monitoring the radiation. The assertions are based on the results of new GPT simulations.

  18. Multiterawatt femtosecond laser system with kilohertz pulse repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, V V; Pestryakov, E V; Laptev, A V; Petrov, V A; Kuptsov, G V; Trunov, V I; Frolov, S A [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2014-05-30

    The basic principles, layout and components are presented for a multiterawatt femtosecond laser system with a kilohertz pulse repetition rate f, based on their parametric amplification and laser amplification of picosecond radiation that pumps the stages of the parametric amplifier. The results of calculations for a step-by-step increase in the output power from the LBO crystal parametric amplifier channel up to the multiterawatt level are presented. By using the developed components in the pump channel of the laser system, the parameters of the regenerative amplifier with the output energy ∼1 mJ at the wavelength 1030 nm and with f = 1 kHz are experimentally studied. The optical scheme of the diode-pumped multipass cryogenic Yb:Y{sub 2}O{sub 3} laser ceramic amplifier is developed and its characteristics are determined that provide the output energy within the range 0.25 – 0.35 J. (lasers)

  19. Multiterawatt femtosecond laser system with kilohertz pulse repetition rate

    Science.gov (United States)

    Petrov, V. V.; Pestryakov, E. V.; Laptev, A. V.; Petrov, V. A.; Kuptsov, G. V.; Trunov, V. I.; Frolov, S. A.

    2014-05-01

    The basic principles, layout and components are presented for a multiterawatt femtosecond laser system with a kilohertz pulse repetition rate f, based on their parametric amplification and laser amplification of picosecond radiation that pumps the stages of the parametric amplifier. The results of calculations for a step-by-step increase in the output power from the LBO crystal parametric amplifier channel up to the multiterawatt level are presented. By using the developed components in the pump channel of the laser system, the parameters of the regenerative amplifier with the output energy ~1 mJ at the wavelength 1030 nm and with f = 1 kHz are experimentally studied. The optical scheme of the diode-pumped multipass cryogenic Yb:Y2O3 laser ceramic amplifier is developed and its characteristics are determined that provide the output energy within the range 0.25 - 0.35 J.

  20. A new source number estimation method based on the beam eigenvalue

    Institute of Scientific and Technical Information of China (English)

    JIANG Lei; CAI Ping; YANG Juan; WANG Yi-ling; XU Dan

    2007-01-01

    Most source number estimation methods based on the eigenvalues are decomposed by covariance matrix in MUSIC algorithm. To develop the source number estimation method which has lower signal to noise ratio and is suitable to both correlated and uncorrelated impinging signals, a new source number estimation method called beam eigenvalue method (BEM) is proposed in this paper.Through analyzing the space power spectrum and the correlation of the line array, the covariance matrix is constructed in a new way, which is decided by the line array shape when the signal frequency is given.Both of the theory analysis and the simulation results show that the BEM method can estimate the source number for correlated signals and can be more effective at lower signal to noise ratios than the normal source number estimation methods.

  1. Femtosecond electron and x-ray source based on laser wakefield accelerator

    CERN Document Server

    Oulianov, D A; Gosztola, D J; Korovyanko, O J; Li, Y; Rey de Castro, R C; Shkrob, I A; Crowell, Robert A.; Gosztola, David J.; Korovyanko, Oleg J.; Li, Yuelin; Oulianov, Dmitri A.; Rey-de-Castro, Roberto C.; Shkrob, Ilya A.

    2006-01-01

    A terawatt tabletop laser wakefield acceleration source of relativistic electrons has been developed in our Terawatt Ultrafast High Field Facility (TUHFF). The preliminary results for ultrafast radiolysis of liquid water using this femtosecond electron source are presented. A TUHFF based femtosecond x-ray source is proposed. Thomson scattering of the accelerated electrons off a counterpropagating terawatt laser beam will be used to generate keV x-ray photons. The expected parameters of this x-ray source have been estimated. The short pulse duration, high flux, and good collimation of the resulting x-ray beam would be conducive for ultrafast time-resolved x-ray absorption studies of short-lived transient species in gases, liquids, and solids. It is argued that the solvation dynamics of Br atoms generated in photoinduced electron detachment from aqueous bromide would make a convenient choice for the first pump-probe experiment using this x-ray source.

  2. Semi-blind source extraction algorithm for fetal electrocardiogram based on generalized autocorrelations and reference signals

    Science.gov (United States)

    Zhang, Hongjuan; Shi, Zhenwei; Guo, Chonghui; Feng, Enmin

    2009-01-01

    Blind source extraction (BSE) has become one of the promising methods in the field of signal processing and analysis, which only desires to extract "interesting" source signals with specific stochastic property or features so as to save lots of computing time and resources. This paper addresses BSE problem, in which desired source signals have some available reference signals. Based on this prior information, we develop an objective function for extraction of temporally correlated sources. Maximizing this objective function, a semi-blind source extraction fixed-point algorithm is proposed. Simulations on artificial electrocardiograph (ECG) signals and the real-world ECG data demonstrate the better performance of the new algorithm. Moreover, comparisons with existing algorithms further indicate the validity of our new algorithm, and also show its robustness to the estimated error of time delay.

  3. Acute Alcohol Effects on Repetition Priming and Word Recognition Memory with Equivalent Memory Cues

    Science.gov (United States)

    Ray, Suchismita; Bates, Marsha E.

    2006-01-01

    Acute alcohol intoxication effects on memory were examined using a recollection-based word recognition memory task and a repetition priming task of memory for the same information without explicit reference to the study context. Memory cues were equivalent across tasks; encoding was manipulated by varying the frequency of occurrence (FOC) of words…

  4. Stimulus-Category and Response-Repetition Effects in Task Switching: An Evaluation of Four Explanations

    Science.gov (United States)

    Druey, Michel D.

    2014-01-01

    In many task-switch studies, task sequence and response sequence interact: Response repetitions produce benefits when the task repeats but produce costs when the task switches. Four different theoretical frameworks have been proposed to explain these effects: a reconfiguration-based account, association-learning models, an episodic-retrieval…

  5. Repetitive Behaviors in Autism and Obsessive-Compulsive Disorder: New Perspectives from a Network Analysis

    Science.gov (United States)

    Ruzzano, Laura; Borsboom, Denny; Geurts, Hilde M.

    2015-01-01

    The association between autism and obsessive-compulsive disorder (OCD) seems largely dependent upon observed similarities in the repetitive behaviors that manifest in both disorders. The aim of this study was to use a network approach to explore the interactions between these behaviors. We constructed a network based on clinician's…

  6. Blind Source Separation Based on Covariance Ratio and Artificial Bee Colony Algorithm

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2014-01-01

    Full Text Available The computation amount in blind source separation based on bioinspired intelligence optimization is high. In order to solve this problem, we propose an effective blind source separation algorithm based on the artificial bee colony algorithm. In the proposed algorithm, the covariance ratio of the signals is utilized as the objective function and the artificial bee colony algorithm is used to solve it. The source signal component which is separated out, is then wiped off from mixtures using the deflation method. All the source signals can be recovered successfully by repeating the separation process. Simulation experiments demonstrate that significant improvement of the computation amount and the quality of signal separation is achieved by the proposed algorithm when compared to previous algorithms.

  7. A high repetition rate, single-frequency Nd:YAG laser oscillator and its characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yoichiro; Oba, Masaki; Kato, Masaaki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-02-01

    For the in-situ measurement of various substances in the atmosphere by using DIAL (Differential Absorption LIDAR), a high repetition rate tunable laser is required to obtain data within a few seconds. As the pump source of the tunable laser, the performance of high repetition rate and high average power is indispensable. For the generation of high quality laser radiation, a laser oscillator with 1 kHz pulse repetition rate is made and seeded with very narrow linewidth single-longitudinal mode laser radiation from the outside of the oscillator cavity and its characteristics are studied. As the results, after the thermal equilibrium of the oscillator laser crystal, a single-longitudinal and near TEM{sub 00} transverse mode are realized at the pulse repetition rate between 0.5 kHz and 1 kHz. Single frequency operation is preserved by controlling the cavity length. The average output power of 3W (3 mJ per pulse) is obtained. It is confirmed that this oscillator has enough performance as a oscillator of MOPA (Master Oscillator Power Amplifier) system. (author)

  8. The golden ratio of gait harmony: repetitive proportions of repetitive gait phases.

    Science.gov (United States)

    Iosa, Marco; Fusco, Augusto; Marchetti, Fabio; Morone, Giovanni; Caltagirone, Carlo; Paolucci, Stefano; Peppe, Antonella

    2013-01-01

    In nature, many physical and biological systems have structures showing harmonic properties. Some of them were found related to the irrational number φ known as the golden ratio that has important symmetric and harmonic properties. In this study, the spatiotemporal gait parameters of 25 healthy subjects were analyzed using a stereophotogrammetric system with 25 retroreflective markers located on their skin. The proportions of gait phases were compared with φ, the value of which is about 1.6180. The ratio between the entire gait cycle and stance phase resulted in 1.620 ± 0.058, that between stance and the swing phase was 1.629 ± 0.173, and that between swing and the double support phase was 1.684 ± 0.357. All these ratios did not differ significantly from each other (F = 0.870, P = 0.422, repeated measure analysis of variance) or from φ (P = 0.670, 0.820, 0.422, resp., t-tests). The repetitive gait phases of physiological walking were found in turn in repetitive proportions with each other, revealing an intrinsic harmonic structure. Harmony could be the key for facilitating the control of repetitive walking. Harmony is a powerful unifying factor between seemingly disparate fields of nature, including human gait.

  9. The Golden Ratio of Gait Harmony: Repetitive Proportions of Repetitive Gait Phases

    Directory of Open Access Journals (Sweden)

    Marco Iosa

    2013-01-01

    Full Text Available In nature, many physical and biological systems have structures showing harmonic properties. Some of them were found related to the irrational number known as the golden ratio that has important symmetric and harmonic properties. In this study, the spatiotemporal gait parameters of 25 healthy subjects were analyzed using a stereophotogrammetric system with 25 retroreflective markers located on their skin. The proportions of gait phases were compared with , the value of which is about 1.6180. The ratio between the entire gait cycle and stance phase resulted in 1.620 ± 0.058, that between stance and the swing phase was 1.629 ± 0.173, and that between swing and the double support phase was 1.684 ± 0.357. All these ratios did not differ significantly from each other (, , repeated measure analysis of variance or from (, resp., t-tests. The repetitive gait phases of physiological walking were found in turn in repetitive proportions with each other, revealing an intrinsic harmonic structure. Harmony could be the key for facilitating the control of repetitive walking. Harmony is a powerful unifying factor between seemingly disparate fields of nature, including human gait.

  10. The effects of unitization on familiarity-based source memory: Testing a behavioral prediction derived from neuroimaging data

    OpenAIRE

    Diana, Rachel A.; Yonelinas, Andrew P; Ranganath, Charan

    2008-01-01

    Performance on tests of source memory is typically based on recollection of contextual information associated with an item. However, recent neuroimaging results have suggested that the perirhinal cortex, a region thought to support familiarity-based item recognition, may support source attributions if source information is encoded as a feature of the relevant item (i.e. “unitized”). We hypothesized that familiarity may contribute to source memory performance if item and source information are...

  11. Detection of impulsive sources from an aerostat-based acoustic array data collection system

    Science.gov (United States)

    Prather, Wayne E.; Clark, Robert C.; Strickland, Joshua; Frazier, Wm. Garth; Singleton, Jere

    2009-05-01

    An aerostat based acoustic array data collection system was deployed at the NATO TG-53 "Acoustic Detection of Weapon Firing" Joint Field Experiment conducted in Bourges, France during the final two weeks of June 2008. A variety of impulsive sources including mortar, artillery, gunfire, RPG, and explosive devices were fired during the test. Results from the aerostat acoustic array will be presented against the entire range of sources.

  12. TBEE: Tier Based Energy Efficient Protocol Providing Sink and Source Mobility in Wireless Sensor Networks

    OpenAIRE

    Siddhartha Chauhan; Lalit Awasthi

    2011-01-01

    In resource constrained wireless sensor networks (WSNs) it is important to utilize energy efficiently. Data dissemination is mainly responsible for the consumption of energy in sensor nodes (SNs). The data dissemination protocols for WSNs should reduce the energy consumption of the SNs. Sink and source mobility is the major challenge for data dissemination protocols. In this paper, a Tier based Energy Efficient protocol (TBEE) providing sink and source mobility in WSNs has been proposed. TBEE...

  13. Carrier phase shifted SPWM based on current sourced multi-modular converter for active power filter

    Institute of Scientific and Technical Information of China (English)

    王立乔; 李建林; 张仲超

    2004-01-01

    A novel current-source active power filter(APF)based on multi-modular converter with carrier phase-shifted SPWM(CPS-SPWM)technique is proposed.With this technique,the effect of equivalent high switching frequency converter is obtained with low switching frequency converter.It is very promising in current-source APF that adopt superconducting magnetic energy storage component.

  14. Evaluation of the Agricultural Non-point Source Pollution in Chongqing Based on PSR Model

    OpenAIRE

    Zhang, Hanwen; MOU, Xinli; Xie, Hui; Lu, Hong; YAN, Xingyun

    2014-01-01

    Through a series of exploration based on PSR framework model, for the purpose of building a suitable Chongqing agricultural non-point source pollution evaluation index system model framework, combined with the presence of Chongqing specific agro-environmental issues, we build a agricultural non-point source pollution assessment index system, and then study the agricultural system pressure, agro-environmental status and human response in total 3 major categories, develope an agricultural non-p...

  15. Luminescence-induced noise in single photon sources based on BBO crystals

    Science.gov (United States)

    Machulka, Radek; Lemr, Karel; Haderka, Ondřej; Lamperti, Marco; Allevi, Alessia; Bondani, Maria

    2014-11-01

    Single-photon sources based on the process of spontaneous parametric down-conversion play a key role in various applied disciplines of quantum optics. We characterize the intrinsic luminescence of BBO crystals as a source of non-removable noise in quantum-optics experiments. By analysing its spectral and temporal properties together with its intensity, we evaluate the impact of luminescence on single-photon state preparation using spontaneous parametric down-conversion.

  16. Gis-Based Route Finding Using ANT Colony Optimization and Urban Traffic Data from Different Sources

    Science.gov (United States)

    Davoodi, M.; Mesgari, M. S.

    2015-12-01

    Nowadays traffic data is obtained from multiple sources including GPS, Video Vehicle Detectors (VVD), Automatic Number Plate Recognition (ANPR), Floating Car Data (FCD), VANETs, etc. All such data can be used for route finding. This paper proposes a model for finding the optimum route based on the integration of traffic data from different sources. Ant Colony Optimization is applied in this paper because the concept of this method (movement of ants in a network) is similar to urban road network and movements of cars. The results indicate that this model is capable of incorporating data from different sources, which may even be inconsistent.

  17. Laser-based X-ray and electron source for X-ray fluorescence studies

    Science.gov (United States)

    Valle Brozas, F.; Crego, A.; Roso, L.; Peralta Conde, A.

    2016-08-01

    In this work, we present a modification to conventional X-rays fluorescence using electrons as excitation source and compare it with the traditional X-ray excitation for the study of pigments. For this purpose, we have constructed a laser-based source capable to produce X-rays as well as electrons. Because of the large penetration depth of X-rays, the collected fluorescence signal is a combination of several material layers of the artwork under study. However, electrons are stopped in the first layers, allowing a more superficial analysis. We show that the combination of both excitation sources can provide extremely valuable information about the structure of the artwork.

  18. High-power, high-repetition-rate performance characteristics of β-BaB₂O₄ for single-pass picosecond ultraviolet generation at 266 nm.

    Science.gov (United States)

    Kumar, S Chaitanya; Casals, J Canals; Wei, Junxiong; Ebrahim-Zadeh, M

    2015-10-19

    We report a systematic study on the performance characteristics of a high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 266 nm based on β-BaB2O4 (BBO). The source, based on single-pass fourth harmonic generation (FHG) of a compact Yb-fiber laser in a two-crystal spatial walk-off compensation scheme, generates up to 2.9 W of average power at 266 nm at a pulse repetition rate of ~80 MHz with a single-pass FHG efficiency of 35% from the green to UV. Detrimental issues such as thermal effects have been studied and confirmed by performing relevant measurements. Angular and temperature acceptance bandwidths in BBO for FHG to 266 nm are experimentally determined, indicating that the effective interaction length is limited by spatial walk-off and thermal gradients under high-power operation. The origin of dynamic color center formation due to two-photon absorption in BBO is investigated by measurements of intensity-dependent transmission at 266 nm. Using a suitable theoretical model, two-photon absorption coefficients as well as the color center densities have been estimated at different temperatures. The measurements show that the two-photon absorption coefficient in BBO at 266 nm is ~3.5 times lower at 200°C compared to that at room temperature. The long-term power stability as well as beam pointing stability is analyzed at different output power levels and focusing conditions. Using cylindrical optics, we have circularized the generated elliptic UV beam to a circularity of >90%. To our knowledge, this is the first time such high average powers and temperature-dependent two-photon absorption measurements at 266 nm are reported at repetition rates as high as ~80 MHz.

  19. High-power, high-repetition-rate performance characteristics of β-BaB₂O₄ for single-pass picosecond ultraviolet generation at 266 nm.

    Science.gov (United States)

    Kumar, S Chaitanya; Casals, J Canals; Wei, Junxiong; Ebrahim-Zadeh, M

    2015-10-19

    We report a systematic study on the performance characteristics of a high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 266 nm based on β-BaB2O4 (BBO). The source, based on single-pass fourth harmonic generation (FHG) of a compact Yb-fiber laser in a two-crystal spatial walk-off compensation scheme, generates up to 2.9 W of average power at 266 nm at a pulse repetition rate of ~80 MHz with a single-pass FHG efficiency of 35% from the green to UV. Detrimental issues such as thermal effects have been studied and confirmed by performing relevant measurements. Angular and temperature acceptance bandwidths in BBO for FHG to 266 nm are experimentally determined, indicating that the effective interaction length is limited by spatial walk-off and thermal gradients under high-power operation. The origin of dynamic color center formation due to two-photon absorption in BBO is investigated by measurements of intensity-dependent transmission at 266 nm. Using a suitable theoretical model, two-photon absorption coefficients as well as the color center densities have been estimated at different temperatures. The measurements show that the two-photon absorption coefficient in BBO at 266 nm is ~3.5 times lower at 200°C compared to that at room temperature. The long-term power stability as well as beam pointing stability is analyzed at different output power levels and focusing conditions. Using cylindrical optics, we have circularized the generated elliptic UV beam to a circularity of >90%. To our knowledge, this is the first time such high average powers and temperature-dependent two-photon absorption measurements at 266 nm are reported at repetition rates as high as ~80 MHz. PMID:26480467

  20. Reciprocity in computer-human interaction: source-based, norm-based, and affect-based explanations.

    Science.gov (United States)

    Lee, Seungcheol Austin; Liang, Yuhua Jake

    2015-04-01

    Individuals often apply social rules when they interact with computers, and this is known as the Computers Are Social Actors (CASA) effect. Following previous work, one approach to understand the mechanism responsible for CASA is to utilize computer agents and have the agents attempt to gain human compliance (e.g., completing a pattern recognition task). The current study focuses on three key factors frequently cited to influence traditional notions of compliance: evaluations toward the source (competence and warmth), normative influence (reciprocity), and affective influence (mood). Structural equation modeling assessed the effects of these factors on human compliance with computer request. The final model shows that norm-based influence (reciprocity) increased the likelihood of compliance, while evaluations toward the computer agent did not significantly influence compliance. PMID:25803145

  1. Identification of sources of pollution and contamination in water distribution networks based on pattern recognition

    Institute of Scientific and Technical Information of China (English)

    Tao TAO; Ying-jun LU; Xiang FU; Kun-lun XIN

    2012-01-01

    An intrusion of contaminants into the water distribution network (WDN) can occur through storage tanks (via animals.dust-carrying bacteria,and infiltration) and pipes.A sensor network could yield useful observations that help identify the location of the source,the strength,the time of occurrence.and the duration of contamination.This paper proposes a methodology for identifying the contamination sources in a water distribution system,which identifies the key characteristics of contamination.such as location,starting time.and injection rates at different time intervals.Based on simplified hypotheses and associated with a high computational efficiency.the methodology is designed to be a simple and easy-to-use tool for water companies to ensure rapid identification of the contamination sources,The proposed methodology identifies the characteristics of pollution sources by matching the dynamic patterns of the simulated and measured concentrations.The application of this methodology to a literature network and a real WDN are illustrated with the aid of an example.The results showed that if contaminants are transported from the sources to the sensors at intervals,then this method can identify the most possible ones from candidate pollution sources.However,if the contamination data is minimal,a greater number of redundant contamination source nodes will be present.Consequently,more data from different sensors obtained through network monitoring are required to effectively use this method for locating multi-sources of contamination in the WDN.

  2. [Long optical path gas detection based on MEMS infrared light source].

    Science.gov (United States)

    Du, Bin-Bin; Zhang, Peng; Gao, Wen-Hong; Shi, Yun-Bo; Zhu, Lin-Quan

    2014-04-01

    According to the requirements of infrared gas sensor for the light source, a broad wavelength, high modulation frequency, low power consumption and small size MEMS infrared light source is chosen as the radiation source, whose performance meets the requirements of infrared sensing system for the light source greatly. However, the infrared light source with the lamberation radiation characteristics is a surface light source, which is still with a large numerical aperture after shaping. It is difficult to increase the detection sensitivity by using a traditional long optical gas cell in a MEMS infrared light source detection system. Based on the dual-wavelength single beam differential detection method, an integrating sphere as the gas cell for long optical path is designed, which is able to realize long optical path for high sensitivity gas detection. The physical dimension is deduced for the equivalent optical path according to the flux conservation principle in the process of light transmission, solving the calculation problem of equivalent optical path of the integrating sphere cell. Using FPGA control chip, the MEMS infrared light source is droved at high frequency modulation and the detector output signal is processed, which makes the external circuit design much simple and flexible. It turns out that 166.7 cm equivalent optical path and the minimum concentration of methane of 0.001 x 10(-6) are achieved by the use of a 5 cm diameter integrating sphere in the research, improving the sensitivity of infrared detection system greatly. PMID:25007612

  3. Agent-based power sharing scheme for active hybrid power sources

    Science.gov (United States)

    Jiang, Zhenhua

    The active hybridization technique provides an effective approach to combining the best properties of a heterogeneous set of power sources to achieve higher energy density, power density and fuel efficiency. Active hybrid power sources can be used to power hybrid electric vehicles with selected combinations of internal combustion engines, fuel cells, batteries, and/or supercapacitors. They can be deployed in all-electric ships to build a distributed electric power system. They can also be used in a bulk power system to construct an autonomous distributed energy system. An important aspect in designing an active hybrid power source is to find a suitable control strategy that can manage the active power sharing and take advantage of the inherent scalability and robustness benefits of the hybrid system. This paper presents an agent-based power sharing scheme for active hybrid power sources. To demonstrate the effectiveness of the proposed agent-based power sharing scheme, simulation studies are performed for a hybrid power source that can be used in a solar car as the main propulsion power module. Simulation results clearly indicate that the agent-based control framework is effective to coordinate the various energy sources and manage the power/voltage profiles.

  4. Open source, web-based machine-learning assisted classification system

    OpenAIRE

    Consarnau Pallarés, Mireia Roser

    2016-01-01

    The aim of this article is to provide a design overview of the web based machine learning assisted multi-user classification system. The design is based on open source standards both for multi-user environment written in PHP using the Laravel framework and a Python based machine learning toolkit, Scikit-Learn. The advantage of the proposed system is that it does not require the domain specific knowledge or programming skills. Machine learning classification tasks are done on the background...

  5. Beach debris on Aruba, Southern Caribbean: Attribution to local land-based and distal marine-based sources.

    Science.gov (United States)

    de Scisciolo, Tobia; Mijts, Eric N; Becker, Tatiana; Eppinga, Maarten B

    2016-05-15

    Accumulation of marine (plastic) debris from local land-based and distal marine-based sources along coastlines is a pressing modern issue. Hitherto, assessing the relative contribution of pollution sources through beach surveys is methodologically challenging. We surveyed ten beaches along the leeward and windward coastlines of Aruba (southern Caribbean) to determine differences in macro- and meso-debris densities. Differences were quantified using three metrics: 1) the gradient in macro-debris density away from the waterfront; 2) the proportion of plastic within macro-debris; 3) the meso-:macro-debris ratio. Overall 42,585 macro-debris items and 884 meso-debris items were collected. The density of near-shore macro-debris, proportion of plastic debris herein, and meso-:macro-debris ratio were highest on the windward coastline. These results suggest that southern Caribbean windward coastlines are mainly exposed to debris originating from distal marine-based sources, and leeward coastlines to local land-based sources. Our metrics clearly reflect these differences, providing novel means to survey debris source origin.

  6. Beach debris on Aruba, Southern Caribbean: Attribution to local land-based and distal marine-based sources.

    Science.gov (United States)

    de Scisciolo, Tobia; Mijts, Eric N; Becker, Tatiana; Eppinga, Maarten B

    2016-05-15

    Accumulation of marine (plastic) debris from local land-based and distal marine-based sources along coastlines is a pressing modern issue. Hitherto, assessing the relative contribution of pollution sources through beach surveys is methodologically challenging. We surveyed ten beaches along the leeward and windward coastlines of Aruba (southern Caribbean) to determine differences in macro- and meso-debris densities. Differences were quantified using three metrics: 1) the gradient in macro-debris density away from the waterfront; 2) the proportion of plastic within macro-debris; 3) the meso-:macro-debris ratio. Overall 42,585 macro-debris items and 884 meso-debris items were collected. The density of near-shore macro-debris, proportion of plastic debris herein, and meso-:macro-debris ratio were highest on the windward coastline. These results suggest that southern Caribbean windward coastlines are mainly exposed to debris originating from distal marine-based sources, and leeward coastlines to local land-based sources. Our metrics clearly reflect these differences, providing novel means to survey debris source origin. PMID:27039956

  7. On the Functions of Lexical Repetition in English Texts

    Institute of Scientific and Technical Information of China (English)

    XIAO Fuliang

    2016-01-01

    Lexical repetition, as a cohesive device of an English text, can help make up a cohesive and coherent text. Therefore, in English textual learning, it is helpful for students to know about different patterns and functions of lexical repetition to improve their English level and ability.

  8. A Negative Effect of Repetition in Episodic Memory

    Science.gov (United States)

    Peterson, Daniel J.; Mulligan, Neil W.

    2012-01-01

    One of the foundational principles of human memory is that repetition (i.e., being presented with a stimulus multiple times) improves recall. In the current study a group of participants who studied a list of cue-target pairs twice recalled fewer targets than a group who studied the pairs only once, a negative repetition effect. Such a…

  9. 38 CFR 21.132 - Repetition of the course.

    Science.gov (United States)

    2010-07-01

    ... (CONTINUED) VOCATIONAL REHABILITATION AND EDUCATION Vocational Rehabilitation and Employment Under 38 U.S.C. Chapter 31 Educational and Vocational Training Services § 21.132 Repetition of the course. (a) Repeating... repetition is necessary to accomplish the veteran's vocational rehabilitation. A veteran repeating a...

  10. 10 CFR 52.8 - Combining licenses; elimination of repetition.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Combining licenses; elimination of repetition. 52.8... NUCLEAR POWER PLANTS General Provisions § 52.8 Combining licenses; elimination of repetition. (a) An applicant for a license under this part may combine in its application several applications for...

  11. Nitrogen laser with a pulse repetition rate of 11 kHz and a beam divergence of 0.5 mrad

    International Nuclear Information System (INIS)

    A repetitively pulsed high-frequency UV nitrogen laser based on magnetic pulse compression (MPC) circuit is developed. The special characteristics of laser operation at pulse repetition rates up to 11 kHz are studied. Lasing with an average power of 1.4 W for a beam divergence of less than 0.5 mrad is obtained. (lasers)

  12. 486nm blue laser operating at 500 kHz pulse repetition frequency

    Science.gov (United States)

    Creeden, Daniel; Blanchard, Jon; Pretorius, Herman; Limongelli, Julia; Setzler, Scott D.

    2016-03-01

    Compact, high power blue light in the 470-490nm region is difficult to generate due to the lack of laser sources which are easily convertible (through parametric processes) to those wavelengths. By using a pulsed Tm-doped fiber laser as a pump source for a 2-stage second harmonic generation (SHG) scheme, we have generated ~2W of 486.5nm light at 500kHz pulse repetition frequency (PRF). To our knowledge, this is the highest PRF and output power achieved in the blue region based on a frequency converted, monolithic fiber laser. This pump laser is a pulsed Tm-doped fiber laser/amplifier which generates 12.8W of 1946nm power at 500kHz PRF with diffraction-limited output from a purely single-mode fiber. The output from this laser is converted to 973nm through second harmonic generation (SHG). The 973nm is then converted to 486.5nm via another SHG stage. This architecture operates with very low peak power, which can be challenging from a nonlinear conversion standpoint. However, the low peak power enables the use of a single-mode monolithic fiber amplifier without undergoing nonlinear effects in the fiber. This also eliminates the need for novel fiber designs, large-mode area fiber, or free-space coupling to rod-type amplifiers, improving reliability and robustness of the laser source. Higher power and conversion efficiency are possible through the addition of Tm-doped fiber amplification stages as well as optimization of the nonlinear conversion process and nonlinear materials. In this paper, we discuss the laser layout, results, and challenges with generating blue light using a low peak power approach.

  13. Transgenerational effects of environmental enrichment on repetitive motor behavior development.

    Science.gov (United States)

    Bechard, Allison R; Lewis, Mark H

    2016-07-01

    The favorable consequences of environmental enrichment (EE) on brain and behavior development are well documented. Much less is known, however, about transgenerational benefits of EE on non-enriched offspring. We explored whether transgenerational effects of EE might extend to the development of repetitive motor behaviors in deer mice. Repetitive motor behaviors are invariant patterns of movement that, across species, can be reduced by EE. We found that EE not only attenuated the development of repetitive behavior in dams, but also in their non-enriched offspring. Moreover, maternal behavior did not seem to mediate the transgenerational effect we found, although repetitive behavior was affected by reproductive experience. These data support a beneficial transgenerational effect of EE on repetitive behavior development and suggest a novel benefit of reproductive experience.

  14. Repetitive DNA Sequences in Wheat and Its Relatives

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-yong; LI Da-yong

    2001-01-01

    Repetitive DNA sequences form a large portion of eukaryote genomes. Using wheat ( Triticum )as a model, the classification, features and functions of repetitive DNA sequences in the Tritieeae grass tribe is reviewed as well as the role of these sequences in genome differentiation, control and regulation of homologous chromosome synapsis and pairing. Transposable elements, as an important portion of dispersed repetitives,may play an essential role in gene mutation of the host. Dynamic models for change of copy number and sequences of the repetitive family are also presented after the models of Charlesworth et al. Application of repetitive DNA sequences in the study of evolution, chromosome fingerprinting and marker assisted gene transfer and breeding are described by taking wheat as an example.

  15. Repetition suppression and its contextual determinants in predictive coding.

    Science.gov (United States)

    Auksztulewicz, Ryszard; Friston, Karl

    2016-07-01

    This paper presents a review of theoretical and empirical work on repetition suppression in the context of predictive coding. Predictive coding is a neurobiologically plausible scheme explaining how biological systems might perform perceptual inference and learning. From this perspective, repetition suppression is a manifestation of minimising prediction error through adaptive changes in predictions about the content and precision of sensory inputs. Simulations of artificial neural hierarchies provide a principled way of understanding how repetition suppression - at different time scales - can be explained in terms of inference and learning implemented under predictive coding. This formulation of repetition suppression is supported by results of numerous empirical studies of repetition suppression and its contextual determinants. PMID:26861557

  16. Repetition and Emotive Communication in Music Versus Speech

    Directory of Open Access Journals (Sweden)

    Elizabeth Hellmuth eMargulis

    2013-04-01

    Full Text Available Music and speech are often placed alongside one another as comparative cases. Their relative overlaps and disassociations have been well explored (e.g. Patel, 2010. But one key attribute distinguishing these two domains has often been overlooked: the greater preponderance of repetition in music in comparison to speech. Recent fMRI studies have shown that familiarity – achieved through repetition – is a critical component of emotional engagement with music (Pereira et al., 2011. If repetition is fundamental to emotional responses to music, and repetition is a key distinguisher between the domains of music and speech, then close examination of the phenomenon of repetition might help clarify the ways that music elicits emotion differently than speech.

  17. Self-controlled KR schedules: does repetition order matter?

    Science.gov (United States)

    Patterson, Jae T; Carter, Michael J; Hansen, Steve

    2013-08-01

    The impact of an experimenter-defined repetition schedule on the utility of a self-controlled KR context during motor skill acquisition was examined. Participants were required to learn three novel spatial-temporal tasks in either a random or blocked repetition schedule with or without the opportunity to control their KR. Results from the retention period showed that participants provided control over their KR schedule in a random repetition schedule demonstrated superior learning. However, performance measures from the transfer test showed that, independent of repetition schedule, learners provided the opportunity to control their KR schedule demonstrated superior transfer performance compared to their yoked counterparts. The dissociated impact of repetition schedule and self-controlled KR schedules on retention and transfer is discussed.

  18. Multi-mJ, kHz picosecond deep UV source based on a frequency-quadrupled cryogenic Yb:YAG laser

    Science.gov (United States)

    Hong, Kyung-Han; Chang, Chun-Lin; Krogen, Peter; Liang, Houkun; Stein, Gregory J.; Moses, Jeffrey; Lai, Chien-Jen; Kärtner, Franz X.

    2015-05-01

    We report on the development of a 2.74-mJ, ~4.2 ps, ~258 nm deep-ultraviolet (DUV) source at 1 kHz based on frequency quadrupling of ~32 mJ, 8.4 ps, ~1030 nm near-infrared (NIR) laser pulses with an excellent beam profile, generated from a diode-pumped, ultrafast hybrid Yb-doped chirped-pulse amplification laser system. We have used a two-stage second harmonic generation scheme at LBO (NIR-to-green) and BBO crystals (green-to-DUV), respectively, to achieve the fourth-harmonic generation (FHG). The NIR-to-DUV conversion efficiency of ~10% in the FHG is obtained. The peak power of the produced DUV laser pulses is as high as 0.56 GW. The beam profiles at near-field and far-field are found to be excellent and the M2 value is measured as ~2.6. We also present the systematic parameter study on the optimization of DUV generation. To our best knowledge, this is the most energetic DUV generation from a diodepumped solid-state laser at kHz repetition rates.

  19. Dissecting the functional anatomy of auditory word repetition

    Directory of Open Access Journals (Sweden)

    Thomas Matthew Hadley Hope

    2014-05-01

    Full Text Available Auditory word repetition involves many different brain regions, whose functions are still far from fully understood. Here, we use a single, multi-factorial, within-subjects fMRI design to identify those regions, and to functionally distinguish the multiple linguistic and non-linguistic processing areas that are all involved in repeating back heard words. The study compared: (1 auditory to visual inputs; (2 phonological to non-phonological inputs; (3 semantic to non-semantic inputs; and (4 speech production to finger-press responses. The stimuli included words (semantic and phonological inputs, pseudowords (phonological input, pictures and sounds of animals or objects (semantic input, and coloured patterns and hums (non-semantic and non-phonological. The speech production tasks involved auditory repetition, reading and naming while the finger press tasks involved one-back matching.The results from the main effects and interactions were compared to predictions from a previously reported functional anatomical model of language based on a meta-analysis of many different neuroimaging experiments. Although many findings from the current experiment replicated those predicted, our within-subject design also revealed novel results by providing sufficient anatomical precision to distinguish several different regions within: (1 the anterior insula (a dorsal region involved in both covert and overt speech production, and a more ventral region involved in overt speech only; (2 the pars orbitalis (with distinct sub-regions responding to phonological and semantic processing; (3 the anterior cingulate and SMA (whose subregions show differential sensitivity to speech and finger press responses; and (4 the cerebellum (with distinct regions for semantic processing, speech production and domain general processing. We also dissociated four different types of phonological effects in, respectively, the left superior temporal sulcus, left putamen, left ventral premoto

  20. Understanding communicative actions: a repetitive TMS study.

    Science.gov (United States)

    Stolk, Arjen; Noordzij, Matthijs L; Volman, Inge; Verhagen, Lennart; Overeem, Sebastiaan; van Elswijk, Gijs; Bloem, Bas; Hagoort, Peter; Toni, Ivan

    2014-02-01

    Despite the ambiguity inherent in human communication, people are remarkably efficient in establishing mutual understanding. Studying how people communicate in novel settings provides a window into the mechanisms supporting the human competence to rapidly generate and understand novel shared symbols, a fundamental property of human communication. Previous work indicates that the right posterior superior temporal sulcus (pSTS) is involved when people understand the intended meaning of novel communicative actions. Here, we set out to test whether normal functioning of this cerebral structure is required for understanding novel communicative actions using inhibitory low-frequency repetitive transcranial magnetic stimulation (rTMS). A factorial experimental design contrasted two tightly matched stimulation sites (right pSTS vs left MT+, i.e., a contiguous homotopic task-relevant region) and tasks (a communicative task vs a visual tracking task that used the same sequences of stimuli). Overall task performance was not affected by rTMS, whereas changes in task performance over time were disrupted according to TMS site and task combinations. Namely, rTMS over pSTS led to a diminished ability to improve action understanding on the basis of recent communicative history, while rTMS over MT+ perturbed improvement in visual tracking over trials. These findings qualify the contributions of the right pSTS to human communicative abilities, showing that this region might be necessary for incorporating previous knowledge, accumulated during interactions with a communicative partner, to constrain the inferential process that leads to action understanding.

  1. Development of a repetitive compact torus injector

    Science.gov (United States)

    Onchi, Takumi; McColl, David; Dreval, Mykola; Rohollahi, Akbar; Xiao, Chijin; Hirose, Akira; Zushi, Hideki

    2013-10-01

    A system for Repetitive Compact Torus Injection (RCTI) has been developed at the University of Saskatchewan. CTI is a promising fuelling technology to directly fuel the core region of tokamak reactors. In addition to fuelling, CTI has also the potential for (a) optimization of density profile and thus bootstrap current and (b) momentum injection. For steady-state reactor operation, RCTI is necessary. The approach to RCTI is to charge a storage capacitor bank with a large capacitance and quickly charge the CT capacitor bank through a stack of integrated-gate bipolar transistors (IGBTs). When the CT bank is fully charged, the IGBT stack will be turned off to isolate banks, and CT formation/acceleration sequence will start. After formation of each CT, the fast bank will be replenished and a new CT will be formed and accelerated. Circuits for the formation and the acceleration in University of Saskatchewan CT Injector (USCTI) have been modified. Three CT shots at 10 Hz or eight shots at 1.7 Hz have been achieved. This work has been sponsored by the CRC and NSERC, Canada.

  2. A Novel Method Based on Oblique Projection Technology for Mixed Sources Estimation

    Directory of Open Access Journals (Sweden)

    Weijian Si

    2014-01-01

    Full Text Available Reducing the computational complexity of the near-field sources and far-field sources localization algorithms has been considered as a serious problem in the field of array signal processing. A novel algorithm caring for mixed sources location estimation based on oblique projection is proposed in this paper. The sources are estimated at two different stages and the sensor noise power is estimated and eliminated from the covariance which improve the accuracy of the estimation of mixed sources. Using the idea of compress, the range information of near-field sources is obtained by searching the partial area instead of the whole Fresnel area which can reduce the processing time. Compared with the traditional algorithms, the proposed algorithm has the lower computation complexity and has the ability to solve the two closed-spaced sources with high resolution and accuracy. The duplication of range estimation is also avoided. Finally, simulation results are provided to demonstrate the performance of the proposed method.

  3. An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability is asses......This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability...... is assessed based on a series of Nyquist diagrams drawn for the terminal impedance of each converter. Thus, the effect of the right half-plane zeros of terminal impedances in the derivation of impedance ratio for paralleled source-source converters is avoided. The interaction between the terminal impedance...... of converter and the passive network can also be predicted by the Nyquist diagrams. This method is applied to evaluate the current and voltage controller interactions of converters in both grid-connected and islanded operations. Simulations and experimental results verify the effectiveness of theoretical...

  4. Direct fiber-coupled single photon source based on a photonic crystal waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Byeong-Hyeon, E-mail: seygene@kaist.ac.kr; Lee, Chang-Min; Lim, Hee-Jin [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of); Schlereth, Thomas W.; Kamp, Martin [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Höfling, Sven [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS (United Kingdom); Lee, Yong-Hee [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of); Graduate School of Nanoscience and Technology (WCU), KAIST, Daejeon 305-701 (Korea, Republic of)

    2015-08-24

    A single photon source plays a key role in quantum applications such as quantum computers and quantum communications. Epitaxially grown quantum dots are one of the promising platforms to implement a good single photon source. However, it is challenging to realize an efficient single photon source based on semiconductor materials due to their high refractive index. Here we demonstrate a direct fiber coupled single photon source with high collection efficiency by employing a photonic crystal (PhC) waveguide and a tapered micro-fiber. To confirm the single photon nature, the second-order correlation function g{sup (2)}(τ) is measured with a Hanbury Brown-Twiss setup. The measured g{sup (2)}(0) value is 0.15, and we can estimate 24% direct collection efficiency from a quantum dot to the fiber.

  5. Atrial fibrillatory signal estimation using blind source extraction algorithm based on high-order statistics

    Institute of Scientific and Technical Information of China (English)

    WANG Gang; RAO NiNi; ZHANG Ying

    2008-01-01

    The analysis and the characterization of atrial fibrillation (AF) requires,in a previous key step,the extraction of the atrial activity (AA) free from 12-lead electrocardiogram (ECG).This contribution proposes a novel non-invasive approach for the AA estimation in AF episodes.The method is based on blind source extraction (BSE) using high order statistics (HOS).The validity and performance of this algorithm are confirmed by extensive computer simulations and experiments on realworld data.In contrast to blind source separation (BSS) methods,BSE only extract one desired signal,and it is easy for the machine to judge whether the extracted signal is AA source by calculating its spectrum concentration,while it is hard for the machine using BSS method to judge which one of the separated twelve signals is AA source.Therefore,the proposed method is expected to have great potential in clinical monitoring.

  6. Direct fiber-coupled single photon source based on a photonic crystal waveguide

    International Nuclear Information System (INIS)

    A single photon source plays a key role in quantum applications such as quantum computers and quantum communications. Epitaxially grown quantum dots are one of the promising platforms to implement a good single photon source. However, it is challenging to realize an efficient single photon source based on semiconductor materials due to their high refractive index. Here we demonstrate a direct fiber coupled single photon source with high collection efficiency by employing a photonic crystal (PhC) waveguide and a tapered micro-fiber. To confirm the single photon nature, the second-order correlation function g(2)(τ) is measured with a Hanbury Brown-Twiss setup. The measured g(2)(0) value is 0.15, and we can estimate 24% direct collection efficiency from a quantum dot to the fiber

  7. GIS-Based Noise Simulation Open Source Software: N-GNOIS

    Science.gov (United States)

    Vijay, Ritesh; Sharma, A.; Kumar, M.; Shende, V.; Chakrabarti, T.; Gupta, Rajesh

    2015-12-01

    Geographical information system (GIS)-based noise simulation software (N-GNOIS) has been developed to simulate the noise scenario due to point and mobile sources considering the impact of geographical features and meteorological parameters. These have been addressed in the software through attenuation modules of atmosphere, vegetation and barrier. N-GNOIS is a user friendly, platform-independent and open geospatial consortia (OGC) compliant software. It has been developed using open source technology (QGIS) and open source language (Python). N-GNOIS has unique features like cumulative impact of point and mobile sources, building structure and honking due to traffic. Honking is the most common phenomenon in developing countries and is frequently observed on any type of roads. N-GNOIS also helps in designing physical barrier and vegetation cover to check the propagation of noise and acts as a decision making tool for planning and management of noise component in environmental impact assessment (EIA) studies.

  8. Identification and spatial patterns of coastal water pollution sources based on GIS and chemometric approach

    Institute of Scientific and Technical Information of China (English)

    ZHOU Feng; GUO Huai-cheng; LIU Yong; HAO Ze-jia

    2007-01-01

    Comprehensive and joint applications of GIS and chemometric approach were applied in identification and spatial patterns of coastal water pollution sources with a large data set (5 years (2000-2004), 17 parameters) obtained through coastal water monitoring of Southern Water Control Zone in Hong Kong. According to cluster analysis the pollution degree was significantly different between September-next May (the 1st period) and June-August (the 2nd period). Based on these results, four potential pollution sources, such as organic/eutrophication pollution, natural pollution, mineral/anthropic pollution and fecal pollution were identified by factor analysis/principal component analysis. Then the factor scores of each monitoring site were analyzed using inverse distance weighting method, and the results indicated degree of the influence by various potential pollution sources differed among the monitoring sites. This study indicated that hybrid approach was useful and effective for identification of coastal water pollution source and spatial pattern.

  9. Evaluation of the Agricultural Non-point Source Pollution in Chongqing Based on PSR Model

    Institute of Scientific and Technical Information of China (English)

    Hanwen; ZHANG; Xinli; MOU; Hui; XIE; Hong; LU; Xingyun; YAN

    2014-01-01

    Through a series of exploration based on PSR framework model,for the purpose of building a suitable Chongqing agricultural nonpoint source pollution evaluation index system model framework,combined with the presence of Chongqing specific agro-environmental issues,we build a agricultural non-point source pollution assessment index system,and then study the agricultural system pressure,agro-environmental status and human response in total 3 major categories,develope an agricultural non-point source pollution evaluation index consisting of 3 criteria indicators and 19 indicators. As can be seen from the analysis,pressures and responses tend to increase and decrease linearly,state and complex have large fluctuations,and their fluctuations are similar mainly due to the elimination of pressures and impact,increasing the impact for agricultural non-point source pollution.

  10. Dynamic character analysis for the arc welding power source based on fuzzy logic

    Institute of Scientific and Technical Information of China (English)

    Wang Zhenmin; Xue Jiaxiang; Wang Fuguang

    2007-01-01

    A lot of experimental methods have been brought forth to assess the dynamic character of the arc welding power source, but up to now, this issue has not been solved very well. In this paper, based on the fuzzy logic reasoning method, a dynamic character assessing model for the arc welding power source was established and used to analyze the dynamic character of the welding power source. Three different types of welding machine have been tested, and the characteristic information of the electrical signals such as re-striking arc voltage, low welding current and so on of the welding process were extracted accurately by using a self-developed welding dynamic arc wavelet analyzer. The experimental results indicate that this model can be used as a new assessing method for the dynamic character of the arc welding power source.

  11. The Effect of Task Instructions on Students' Use of Repetition in Argumentative Discourse

    Science.gov (United States)

    Gilabert, Sandra; Garcia-Mila, Merce; Felton, Mark K.

    2013-11-01

    The reasoning belief of argumentum ad nauseam assumes that when someone repeats something often enough, he or she becomes more convincing. The present paper analyses the use of this strategy by seventh-grade students in an argumentation task. Sixty-five students (mean age: 12.2, SD = 0.4) from a public school in a mid-sized urban environment took part in the study. The students were asked to either argue to convince an opposing partner or argue to reach consensus with an opposing partner on three dilemmas that dealt with energy sources. Data were gathered according to a between-groups design that included one independent variable (argumentative goal: to convince vs. to reach consensus) and one dependent variable (the degree of argumentative repetitions). We predicted that in the condition to convince their partner, the students would use the repetition strategy more often in their attempts to be persuasive. Our findings show that the mean number of argumentative repetitions was significantly higher for the persuasion group for both of the most frequent argumentative structures (claim and claim data). The mean percentage of repeated claims for the persuasion condition was 86.2 vs. 69.0 for the consensus condition. For the claim data, the mean percentage for the persuasion group was 35.2 vs. 24.3 for the consensus group. Also, students in the persuasion group tended to repeat one idea many times rather than repeating many ideas a few times within the same argumentative structure. The results of our study support the hypothesis that the goal of the argumentative task mediates argumentative discourse and, more concretely, the rate of repetitions and the conceptual diversity of the statements. These differences in rates of repetition and conceptual diversity are related to the amount of learning produced by the instructional goal. We apply Mercer's idea that not all classroom argumentation tasks promote learning equally.

  12. Key Ground-Based and Space-Based Assets to Disentangle Magnetic Field Sources in the Earth's Environment

    Science.gov (United States)

    Chulliat, A.; Matzka, J.; Masson, A.; Milan, S. E.

    2016-10-01

    The magnetic field measured on the ground or in space is the addition of several sources: from flows within the Earth's core to electric currents in distant regions of the magnetosphere. Properly separating and characterizing these sources requires appropriate observations, both ground-based and space-based. In the present paper, we review the existing observational infrastructure, from magnetic observatories and magnetometer arrays on the ground to satellites in low-Earth (Swarm) and highly elliptical (Cluster) orbits. We also review the capability of SuperDARN to provide polar ionospheric convection patterns supporting magnetic observations. The past two decades have been marked by exciting new developments in all observation types. We review these developments, focusing on how they complement each other and how they have led or could lead in the near future to improved separation and modeling of the geomagnetic sources.

  13. Feasibility and impact analysis of a renewable energy source (RES)-based energy system in Korea

    International Nuclear Information System (INIS)

    In this study, we analyze the feasibility and impacts of a renewable energy source (RES)-based electricity supply system of future Korea. To achieve this goal, we first developed different scenarios for increasing the contribution of RES by lowering the rate of i) nuclear power, ii) thermal power, iii) both nuclear and thermal power, and iv) these scenarios with real-world constraints. Based on the generated scenarios, we then specified the established systems with practical strategies which encourage different renewable sources (wind, solar photovoltaic, biomass, and waste). Finally, we analyzed the impacts of the established RES-based systems according to various criteria: the total required cost, the dependence on imported energy, CO2 emissions, and land use. The results show that the RES-based system that utilizes wind energy as its main source by steadily decreasing the rate of thermal power for electricity generation is the most affordable for future Korean electricity system. We also identify the merits and drawbacks of the analyzed systems and provide relevant recommendations for the establishment of a sustainable energy system for Korea. These findings will support policy makers in integrating quantitative assessments into energy-related policy design and implementation. - Highlights: • We model and analyze RES-based electricity supply system in Korea. • Impact analysis includes: economic, energy security, environmental protection aspects. • We also evaluate different strategies to establish RES-based system. • We show that wind energy-based system is the most affordable for Korea

  14. A GIS Based Variable Source Area Model for Large-scale Basin Hydrology

    Directory of Open Access Journals (Sweden)

    Rajesh Vijaykumar Kherde

    2014-05-01

    Full Text Available A geographic information system-based rainfall runoff model that simulate variable source area runoff using topographic features of the basin is presented. The model simulate the flow processes on daily time step basis and has four non linear stores viz. Interception store, soil moisture store, channel store and ground water store. Source area fraction is modelled as a function of antecedent soil moisture, net rainfall and pore capacity raised to the power of areal average topographic index (. Source area fraction is used in conjuction with topographic index to develop linear relations for runoff, Infiltration and interflow. An exponential relation is developed for lower zone evapotranspiration and non-linear exponential relations to model macropore flow and base flow are proposed.

  15. Shunt PWM advanced var compensators based on voltage source inverters for Facts applications

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Pedro G.; Misaka, Isamu; Watanabe, Edson H. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1994-12-31

    Increased attention has been given to improving power system operation. This paper presents modeling, analysis and design of reactive shunt power compensators based on PWM-Voltage Source Inverters (Pulse Width Modulation -Voltage Source Inverters). (Pulse Width Modulation - Voltage Source Inverters). The control algorithm is based on new concepts of instantaneous active and reactive power theory. The objective is to show that with a small capacitor in the side of a 3-phase PWM-VSI it is possible to synthesize a variable reactive (capacitive or inductive) device. Design procedures and experimental results are presented. The feasibility of this method was verified by digital simulations and measurements on a small scale model. (author) 9 refs., 12 figs.

  16. Method to fabricate portable electron source based on nitrogen incorporated ultrananocrystalline diamond (N-UNCD)

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Divan, Ralu; Posada, Chrystian M.; Castano, Carlos H.; Grant, Edwin J.; Lee, Hyoung K.

    2016-03-29

    A source cold cathode field emission array (FEA) source based on ultra-nanocrystalline diamond (UNCD) field emitters. This system was constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation a flat-panel source can be used in tomography, radiography, or tomosynthesis. Furthermore, the unit can be used as a portable electron or X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube "forest" (CNT) cathodes. Furthermore, UNCDs have better mechanical and thermal properties as compared to CNT tips which further extend the lifetime of UNCD based FEA.

  17. Blind source separation of ship-radiated noise based on generalized Gaussian model

    Institute of Scientific and Technical Information of China (English)

    Kong Wei; Yang Bin

    2006-01-01

    When the distribution of the sources cannot be estimated accurately, the ICA algorithms failed to separate the mixtures blindly. The generalized Gaussian model (GGM) is presented in ICA algorithm since it can model nonGaussian statistical structure of different source signals easily. By inferring only one parameter, a wide class of statistical distributions can be characterized. By using maximum likelihood (ML) approach and natural gradient descent, the learning rules of blind source separation (BSS) based on GGM are presented. The experiment of the ship-radiated noise demonstrates that the GGM can model the distributions of the ship-radiated noise and sea noise efficiently, and the learning rules based on GGM gives more successful separation results after comparing it with several conventional methods such as high order cumulants and Gaussian mixture density function.

  18. Measuring Acoustic Wave Transit Time in Furnace Based on Active Acoustic Source Signal

    Institute of Scientific and Technical Information of China (English)

    Zhen Luo; Feng Tian; Xiao-Ping Sun

    2007-01-01

    Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new method for measuring transit time of acoustic wave based on active acoustic source signal is proposed in this paper, which includes the followings: the time when the acoustic source signal arrives at the two sensors is measured first; then, the difference of two arriving time arguments is computed, thereby we get the transit time of the acoustic wave between two sensors installed on the two sides of the furnace. Avoiding the restriction on acoustic source signal and background noise, the new method can get the transit time of acoustic wave with higher precision and stronger ability of resisting noise interference.

  19. Internet-Based Sources of Information Which Can Be Used to Study the Internationalization Process

    Science.gov (United States)

    Danford, Gerard L.

    2008-01-01

    This review shows how the Internet can support learning about the process of internationalization. A description of how Internet-based sources of information can be used by students when investigating internationalization has not been made. However, the Internet and its role during a corporation's foreign market expansion has not been investigated…

  20. Joint source-channel coding for wireless object-based video communications utilizing data hiding.

    Science.gov (United States)

    Wang, Haohong; Tsaftaris, Sotirios A; Katsaggelos, Aggelos K

    2006-08-01

    In recent years, joint source-channel coding for multimedia communications has gained increased popularity. However, very limited work has been conducted to address the problem of joint source-channel coding for object-based video. In this paper, we propose a data hiding scheme that improves the error resilience of object-based video by adaptively embedding the shape and motion information into the texture data. Within a rate-distortion theoretical framework, the source coding, channel coding, data embedding, and decoder error concealment are jointly optimized based on knowledge of the transmission channel conditions. Our goal is to achieve the best video quality as expressed by the minimum total expected distortion. The optimization problem is solved using Lagrangian relaxation and dynamic programming. The performance of the proposed scheme is tested using simulations of a Rayleigh-fading wireless channel, and the algorithm is implemented based on the MPEG-4 verification model. Experimental results indicate that the proposed hybrid source-channel coding scheme significantly outperforms methods without data hiding or unequal error protection.

  1. Bright single photon source based on self-aligned quantum dot–cavity systems

    DEFF Research Database (Denmark)

    Maier, Sebastian; Gold, Peter; Forchel, Alfred;

    2014-01-01

    We report on a quasi-planar quantum-dot-based single-photon source that shows an unprecedented high extraction efficiency of 42% without complex photonic resonator geometries or post-growth nanofabrication. This very high efficiency originates from the coupling of the photons emitted by a quantum...

  2. Presence and sources of anthropogenic perfluorinated alkyl acids in tap-water based beverages

    NARCIS (Netherlands)

    C. Eschauzier; M. Hoppe; M. Schlummer; P. de Voogt

    2012-01-01

    This study investigates the presence and sources of perfluorinated alkyl acids (PFAAs) in tap water and corresponding tap-water based beverages such as coffee and cola collected in the city of Amsterdam, The Netherlands. Exposure pathways studies have shown that low concentrations of PFAA in tap wat

  3. A source-based fast-neutron facility for precision irradiations

    CERN Document Server

    Scherzinger, J; Davatz, G; Fissum, K G; Gendotti, U; Hall-Wilton, R; Hansson, A; Håkansson, E; Jebali, R; Kanaki, K; Lundin, M; Nilsson, B; Svensson, H

    2014-01-01

    We report on a source-based fast-neutron facility that has been developed for precision irradiations. Well-understood shielding, coincidence, and time-of-flight measurement techniques are employed to produce a polychromatic energy-tagged neutron beam.

  4. Latin Revived: Source-Based Vocabulary Lessons Courtesy of Harry Potter

    Science.gov (United States)

    Nilsen, Alleen Pace; Nilsen, Don L. F.

    2006-01-01

    Teachers can build on students' familiarity with and respect for the Harry Potter books to create source-based vocabulary lessons. The idea is to work with the Latin roots that J. K. Rowling uses to create original names for places, people, and magical charms and then to extend students' knowledge through exploration of additional English words…

  5. Estimation of Methane Emissions from Municipal Solid Waste Landfills in China Based on Point Emission Sources

    Directory of Open Access Journals (Sweden)

    Cai Bo-Feng

    2014-01-01

    Citation: Cai, B.-F., Liu, J.-G., Gao, Q.-X., et al., 2014. Estimation of methane emissions from municipal solid waste landfills in China based on point emission sources. Adv. Clim. Change Res. 5(2, doi: 10.3724/SP.J.1248.2014.081.

  6. Near field acoustic holography based on the equivalent source method and pressure-velocity transducers

    DEFF Research Database (Denmark)

    Zhang, Y.-B.; Chen, X.-Z.; Jacobsen, Finn

    2009-01-01

    The advantage of using the normal component of the particle velocity rather than the sound pressure in the hologram plane as the input of conventional spatial Fourier transform based near field acoustic holography (NAH) and also as the input of the statistically optimized variant of NAH has recen...... generated by sources on the two sides of the hologram plane is also examined....

  7. Skill learning in mirror reading: how repetition determines acquisition.

    Science.gov (United States)

    Ofen-Noy, N; Dudai, Y; Karni, A

    2003-07-01

    Practice makes perfect, but the role of repetitions in skill learning is not yet fully understood. For example, given a similar number of trials on a given task, it is debated whether repeating and non-repeating items are learned by the same neural process. When one is given training with both types of items--does one learn two separate skills, or only one? Here we show, using a mirror reading task, that practice trials with trial-unique words, and practice trials with repeated words, count towards learning to a different degree. There was no interaction between the time-course of learning repeated and unique words even within the same individuals given mixed training. While repeated words were learned faster than unique words, the repetitions-dependent gains diminished with training beyond a small number of repetitions. Moreover, the gains in performance could not be accounted for solely by the number of repetitions, as assumed by power-law models of learning; rather, the passage of time was a critical factor. Finally, our results suggest that although both repeated and new words were learned by both declarative and procedural memory mechanisms, even a single repetition of specific words could lead to the establishment of a selective differential representation in memory. The results are compatible with the notion of a repetition-sensitive process, triggered by specific repeating events. This 'repetition counter' may be a critical trigger for the effective formation of procedural as well as some type of declarative memory.

  8. Repetitive transcranial magnetic stimulation in psychiatry

    Directory of Open Access Journals (Sweden)

    Biswa Ranjan Mishra

    2011-01-01

    Full Text Available Repetitive transcranial magnetic stimulation (rTMS is a non-invasive and relatively painless tool that has been used to study various cognitive functions as well as to understand the brain-behavior relationship in normal individuals as well as in those with various neuropsychiatric disorders. It has also been used as a therapeutic tool in various neuropsychiatric disorders because of its ability to specifically modulate distinct brain areas. Studies have shown that repeated stimulation at low frequency produces long-lasting inhibition, which is called as long-term depression, whereas repeated high-frequency stimulation can produce excitation through long-term potentiation. This paper reviews the current status of rTMS as an investigative and therapeutic modality in various neuropsychiatric disorders. It has been used to study the cortical and subcortical functions, neural plasticity and brain mapping in normal individuals and in various neuropsychiatric disorders. rTMS has been most promising in the treatment of depression, with an overall milder adverse effect profile compared with electroconvulsive therapy. In other neuropsychiatric disorders such as schizophrenia, mania, epilepsy and substance abuse, it has been found to be useful, although further studies are required to establish therapeutic efficacy. It appears to be ineffective in the treatment of obsessive compulsive disorder. There is a paucity of studies of efficacy and safety of rTMS in pediatric and geriatric population. Although it appears safe, further research is required to optimize its efficacy and reduce the side-effects. Magnetic seizure therapy, which involves producing seizures akin to electroconvulsive therapy, appears to be of comparable efficacy in the treatment of depression with less cognitive adverse effects.

  9. Epithelial topography for repetitive tooth formation

    Directory of Open Access Journals (Sweden)

    Marcia Gaete

    2015-12-01

    Full Text Available During the formation of repetitive ectodermally derived organs such as mammary glands, lateral line and teeth, the tissue primordium iteratively initiates new structures. In the case of successional molar development, new teeth appear sequentially in the posterior region of the jaw from Sox2+ cells in association with the posterior aspect of a pre-existing tooth. The sequence of molar development is well known, however, the epithelial topography involved in the formation of a new tooth is unclear. Here, we have examined the morphology of the molar dental epithelium and its development at different stages in the mouse in vivo and in molar explants. Using regional lineage tracing we show that within the posterior tail of the first molar the primordium for the second and third molar are organized in a row, with the tail remaining in connection with the surface, where a furrow is observed. The morphology and Sox2 expression of the tail retains characteristics reminiscent of the earlier stages of tooth development, such that position along the A-P axes of the tail correlates with different temporal stages. Sox9, a stem/progenitor cell marker in other organs, is expressed mainly in the suprabasal epithelium complementary with Sox2 expression. This Sox2 and Sox9 expressing molar tail contains actively proliferating cells with mitosis following an apico-basal direction. Snail2, a transcription factor implicated in cell migration, is expressed at high levels in the tip of the molar tail while E-cadherin and laminin are decreased. In conclusion, our studies propose a model in which the epithelium of the molar tail can grow by posterior movement of epithelial cells followed by infolding and stratification involving a population of Sox2+/Sox9+ cells.

  10. Repetition enhancement and memory effects for duration.

    Science.gov (United States)

    Wiener, Martin; Thompson, James C

    2015-06-01

    A remarkable aspect of conscious perception is that moments carryover from one to the next, also known as temporal continuity. This ability is thus crucial for detecting regularities, such as in speech and music, and may rely on an accurate perception of time. Investigations of human time perception have detailed two electroencephalographic (EEG) components associated with timing, the contingent negative variation (CNV) and late positive component of timing (LPCt); however, the precise roles of these components in timing remain elusive. Recently, we demonstrated that the perception of duration is influenced by durations presented on prior trials, which we explained by the creation of an implicit memory standard that adapts to local changes in sequence presentation. Here, we turn to the neural basis of this effect. Human participants performed a temporal bisection task in which they were required to classify the duration of auditory stimuli into short and long duration categories; crucially, the presentation order was first-order counterbalanced, allowing us to measure the effect of each presented duration on the next. EEG recordings revealed that the CNV and LPCt signals both covaried with the duration presented on the current trial, with CNV predicting reaction time and LPCt predicting choice. Additionally, both signals covaried with the duration presented in the prior trial but in different ways, with the CNV amplitude reflecting the change in the memory standard and the LPCt reflecting decision uncertainty. Furthermore, we observed a repetition enhancement effect of duration only for the CNV, suggesting that this signal additionally indexes the similarity of successive durations. These findings demonstrate dissociable roles for the CNV and LPCt, and demonstrate that both signals are continuously updated on a trial-by-trial basis that reflects shifts in temporal decisions. PMID:25818689

  11. Ultrafast high-repetition imaging of fuel sprays using picosecond fiber laser.

    Science.gov (United States)

    Purwar, Harsh; Wang, Hongjie; Tang, Mincheng; Idlahcen, Saïd; Rozé, Claude; Blaisot, Jean-Bernard; Godin, Thomas; Hideur, Ammar

    2015-12-28

    Modern diesel injectors operate at very high injection pressures of about 2000 bar resulting in injection velocities as high as 700 m/s near the nozzle outlet. In order to better predict the behavior of the atomization process at such high pressures, high-resolution spray images at high repetition rates must be recorded. However, due to extremely high velocity in the near-nozzle region, high-speed cameras fail to avoid blurring of the structures in the spray images due to their exposure time. Ultrafast imaging featuring ultra-short laser pulses to freeze the motion of the spray appears as an well suited solution to overcome this limitation. However, most commercial high-energy ultrafast sources are limited to a few kHz repetition rates. In the present work, we report the development of a custom-designed picosecond fiber laser generating ∼ 20 ps pulses with an average power of 2.5 W at a repetition rate of 8.2 MHz, suitable for high-speed imaging of high-pressure fuel jets. This fiber source has been proof tested by obtaining backlight images of diesel sprays issued from a single-orifice injector at an injection pressure of 300 bar. We observed a consequent improvement in terms of image resolution compared to standard white-light illumination. In addition, the compactness and stability against perturbations of our fiber laser system makes it particularly suitable for harsh experimental conditions. PMID:26832004

  12. A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

    Science.gov (United States)

    Döpp, A.; Guillaume, E.; Thaury, C.; Lifschitz, A.; Sylla, F.; Goddet, J.-P.; Tafzi, A.; Iaquanello, G.; Lefrou, T.; Rousseau, P.; Conejero, E.; Ruiz, C.; Ta Phuoc, K.; Malka, V.

    2016-09-01

    Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance with GEANT4 Monte-Carlo simulations, we measure a γ-ray source size of less than 100 μm for a 0.5 mm tantalum converter placed at 2 mm from the accelerator exit. Furthermore we present radiographs of image quality indicators.

  13. Long range wind lidars based on novel high spectral brilliance all-fibered sources

    Science.gov (United States)

    Lombard, L.; Dolfi-Bouteyre, A.; Besson, C.; Augère, B.; Bourdon, P.; Durécu, A.; Goular, D.; Le Gouët, J.; Planchat, C.; Renard, W.; Valla, M.; Canat, G.

    2015-10-01

    New Lidar applications related to aircraft safety in the area of an airport include mapping wind velocity and monitoring turbulences within a radius longer than 8km in a short acquisition time (360° map in 1 minute). During landing and takeoff, a minimal distance separation between aircrafts is set by referring to wake turbulence categories. However, it was shown that wake vortices can dissipate quicker because of atmospheric turbulence (characterized by eddy dissipation rate - EDR) or can be transported out of the way on oncoming traffic by cross-winds. Long range scanning Lidars provide radial wind data that can be used to calculate EDR. To reach long range within a short acquisition time, coherent wind Lidars require high power (~kW), narrow linewidth (few MHz) pulsed laser sources with nearly TF limited pulse duration (~1μs). Eyesafe, all-fiber laser sources based on MOPFA (master oscillator, power fiber amplifier) architecture offer many advantages over bulk sources such as low sensitivity to vibrations, efficiency and versatility. However, narrow linewidth pulsed fiber lasers and amplifiers are usually limited by nonlinear effects such as stimulated Brillouin scattering (SBS) to 300W with commercial fibers. We investigated various solutions to push this limit further. For example, a source based on a new fiber composition yielded a peak power of 1120W for 650ns pulse duration with excellent beam quality. Based on these innovative solutions we built a Lidar with a record range of 16km in 0.1s averaging time. In this proceeding, we present some recent results obtained with our wind Lidars based on these high power sources with record ranges. EDR measurements using the developed algorithm based on structure function calculation are presented, as well as its validation with simulations and measurements campaign results.

  14. Detection of point sources on two-dimensional images based on peaks

    CERN Document Server

    Lopez-Caniego, M; Sanz, J L; Barreiro, R B

    2005-01-01

    This article considers the detection of point sources in two dimensional astronomical images. The detection scheme we propose is based on peak statistics. We discuss the example of the detection of far galaxies in Cosmic Microwave Background experiments throughout the paper, although the method we present is totally general and can be used in many other fields of data analysis. We assume sources with a Gaussian profile --that is a fair approximation of the profile of a point source convolved with the detector beam in microwave experiments-- on a background modeled by a homogeneous and isotropic Gaussian random field characterized by a scale-free power spectrum. Point sources are enhanced with respect to the background by means of linear filters. After filtering, we identify local maxima and apply our detection scheme, a Neyman-Pearson detector that defines our region of acceptance based on the a priori pdf of the sources and the ratio of number densities. We study the different performances of some linear fil...

  15. Three-dimensional localization of in vivo bioluminescent source based on multispectral imaging

    Science.gov (United States)

    Feng, Jinchao; Jia, Kebin; Tian, Jie; Yan, Guorui; Zhu, Shouping

    2009-02-01

    Bioluminescence tomography (BLT) is a novel in vivo technique in small animal studies, which can reveal the molecular and cellular information at the whole-body small animal level. At present, there is an increasing interest in multispectral bioluminescence tomography, since multispectral data acquisition could improve the BLT performance significantly. In view to the ill-posedness of BLT problem, we develop an optimal permissible source region strategy to constrain the possible solution of the source by utilizing spectrum character of bioluminescent source. Then a linear system to link the measured data with the unknown light source variables is established by utilizing the optimal permissible region strategy based on adaptive finite element analysis. Furthermore, singular value decomposition analysis is used for data dimensionality reduction and improving computational efficiency in multispectral case. The reconstructed speed and stability benefit from adaptive finite element, the permissible region strategy and singular value decomposition. In the numerical simulation, the heterogeneous phantom experiment has been used to evaluate the performance of the proposed algorithm with the Monte Carlo based synthetic data. The reconstruction results demonstrate the merits and potential of our methodology for localizing bioluminescent source.

  16. Gearbox Fault Diagnosis in a Wind Turbine Using Single Sensor Based Blind Source Separation

    Directory of Open Access Journals (Sweden)

    Yuning Qian

    2016-01-01

    Full Text Available This paper presents a single sensor based blind source separation approach, namely, the wavelet-assisted stationary subspace analysis (WSSA, for gearbox fault diagnosis in a wind turbine. Continuous wavelet transform (CWT is used as a preprocessing tool to decompose a single sensor measurement data into a set of wavelet coefficients to meet the multidimensional requirement of the stationary subspace analysis (SSA. The SSA is a blind source separation technique that can separate the multidimensional signals into stationary and nonstationary source components without the need for independency and prior information of the source signals. After that, the separated nonstationary source component with the maximum kurtosis value is analyzed by the enveloping spectral analysis to identify potential fault-related characteristic frequencies. Case studies performed on a wind turbine gearbox test system verify the effectiveness of the WSSA approach and indicate that it outperforms independent component analysis (ICA and empirical mode decomposition (EMD, as well as the spectral-kurtosis-based enveloping, for wind turbine gearbox fault diagnosis.

  17. Overview of receptor-based source apportionment studies for speciated atmospheric mercury

    Directory of Open Access Journals (Sweden)

    I. Cheng

    2015-02-01

    Full Text Available Receptor-based source apportionment studies of speciated atmospheric mercury are not only concerned with source contributions, but also the influence of transport, transformation, and deposition processes on speciated atmospheric mercury concentrations at receptor locations. Previous studies applied multivariate receptor models including Principal Components Analysis and Positive Matrix Factorization, and back trajectory receptor models including Potential Source Contribution Function, Gridded Frequency Distributions, and Concentration-back trajectory models. Anthropogenic combustion sources, crustal/soil dust, and chemical and physical processes, such as gaseous elemental mercury (GEM oxidation reactions, boundary layer mixing, and GEM flux from surfaces, were inferred from the multivariate studies, which were predominantly conducted at receptor sites in Canada and the US. Back trajectory receptor models revealed potential impacts of large industrial areas such as the Ohio River Valley in the US and throughout China, metal smelters, mercury evasion from the ocean and Great Lakes, and free troposphere transport on receptor measurements. Input data and model parameters specific to atmospheric mercury receptor models are summarized and model strengths and weaknesses are also discussed. One area of improvement that applies to all receptor models is the greater focus on evaluating the accuracy of receptor models at identifying potential speciated atmospheric mercury sources, source locations, and chemical and physical processes in the atmosphere.

  18. Collimating lens for light-emitting-diode light source based on non-imaging optics.

    Science.gov (United States)

    Wang, Guangzhen; Wang, Lili; Li, Fuli; Zhang, Gongjian

    2012-04-10

    A collimating lens for a light-emitting-diode (LED) light source is an essential device widely used in lighting engineering. Lens surfaces are calculated by geometrical optics and nonimaging optics. This design progress does not rely on any software optimization and any complex iterative process. This method can be used for any type of light source not only Lambertian. The theoretical model is based on point source. But the practical LED source has a certain size. So in the simulation, an LED chip whose size is 1 mm*1 mm is used to verify the feasibility of the model. The mean results show that the lenses have a very compact structure and good collimating performance. Efficiency is defined as the ratio of the flux in the illuminated plane to the flux from LED source without considering the lens material transmission. Just investigating the loss in the designed lens surfaces, the two types of lenses have high efficiencies of more than 90% and 99%, respectively. Most lighting area (possessing 80% flux) radii are no more than 5 m when the illuminated plane is 200 m away from the light source. PMID:22505154

  19. Definitions of database files and fields of the Personal Computer-Based Water Data Sources Directory

    Science.gov (United States)

    Green, J. Wayne

    1991-01-01

    This report describes the data-base files and fields of the personal computer-based Water Data Sources Directory (WDSD). The personal computer-based WDSD was derived from the U.S. Geological Survey (USGS) mainframe computer version. The mainframe version of the WDSD is a hierarchical data-base design. The personal computer-based WDSD is a relational data- base design. This report describes the data-base files and fields of the relational data-base design in dBASE IV (the use of brand names in this abstract is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey) for the personal computer. The WDSD contains information on (1) the type of organization, (2) the major orientation of water-data activities conducted by each organization, (3) the names, addresses, and telephone numbers of offices within each organization from which water data may be obtained, (4) the types of data held by each organization and the geographic locations within which these data have been collected, (5) alternative sources of an organization's data, (6) the designation of liaison personnel in matters related to water-data acquisition and indexing, (7) the volume of water data indexed for the organization, and (8) information about other types of data and services available from the organization that are pertinent to water-resources activities.

  20. Clinical application of repetitive transcranial magnetic stimulation in stroke rehabilitation

    Institute of Scientific and Technical Information of China (English)

    Joonho Shin; EunJoo Yang; KyeHee Cho; Carmelo L Barcenas; Woo Jin Kim; Yusun Min; Nam-Jong Paik

    2012-01-01

    Proper stimulation to affected cerebral hemisphere would promote the functional recovery of patients with stroke. Effects of repetitive transcranial magnetic stimulation on cortical excitability can be can be altered by the stimulation frequency, intensity and duration. There has been no consistent recognition regarding the best stimulation frequency and intensity. This study reviews the intervention effects of repetitive transcranial stimulation on motor impairment, dysphagia, visuospatial neglect and aphasia, and summarizes the stimulation frequency, intensity and area for repetitive transcranial magnetic stimulation to yield the best therapeutic effects.

  1. Multi-gigahertz repetition rate ultrafast waveguide lasers mode-locked with graphene saturable absorbers

    Science.gov (United States)

    Obraztsov, P. A.; Okhrimchuk, A. G.; Rybin, M. G.; Obraztsova, E. D.; Garnov, S. V.

    2016-08-01

    We report the development of an approach to build compact waveguide lasers that operate in the stable fundamental mode-locking regime with multigigahertz repetition rates. The approach is based on the use of depressed cladding multi- or single-mode waveguides fabricated directly in the active laser crystal using the femtosecond laser inscription method and a graphene saturable absorber. Using this approach we achieve the stable self-starting mode-locking operation of a diode-pumped waveguide Nd:YAG laser that delivers picosecond pulses at a repetition rate of up to 11.5 GHz with an average power of 12 mW at a central wavelength of 1064 nm. The saturable absorbers are formed through the chemical vapor deposition of single-layer graphene on the output coupler mirror or directly on the end facet of the laser crystal. The stable self-starting mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with an intracavity interferometer. The method developed for the creation of compact ultrashort pulse laser generators with gigahertz repetition rates can be extended further and applied for the development of compact high-repetition rate lasers that operate at a wide range of IR wavelengths.

  2. iPhone forensics based on Macintosh open source and freeware tools

    Science.gov (United States)

    Höne, Thomas; Creutzburg, Reiner

    2011-02-01

    The aim of this article is to show the usefulness of Mac OS X based open source tools for forensic investigation of modern iPhones. It demonstrates how important data stored in the iPhone is investigated. Two different scenarios of investigations are presented that are well-suited for a forensics lab work in university. This work shows how to analyze an Apple iPhone using open source and freeware tools. Important data used in a forensics investigation, which are possibly stored on a mobile device are presented. Also the superstructure and functions of the iPhone are explained.

  3. CO sub 2 sources for microalgae-based liquid fuel production

    Energy Technology Data Exchange (ETDEWEB)

    Feinberg, D.; Karpuk, M.

    1990-08-01

    Researchers in the Aquatic Species Program at the Solar Energy Research Institute are developing species of microalgae that have high percentages of lipids, or oils. These lipids can be extracted and converted to diesel fuel substitutes. Because microalgae need carbon dioxide (CO{sub 2}) as a nutrient, optimal microalgae growth occurs in CO{sub 2}-saturated solutions. For this reason, the authors of this study sought to identify possible large-scale sources of CO{sub 2} for microalgae-based liquid fuels production. The authors concluded that several such promising sources exist. 42 refs., 14 figs., 10 tabs.

  4. Z-Source-Inverter-Based Flexible Distributed Generation System Solution for Grid Power Quality Improvement

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Vilathgamuwa, D. M.; Loh, Poh Chiang;

    2009-01-01

    Distributed generation (DG) systems are usually connected to the grid using power electronic converters. Power delivered from such DG sources depends on factors like energy availability and load demand. The converters used in power conversion do not operate with their full capacity all the time......-stage buck-boost inverter, recently proposed Z-source inverter (ZSI) is a good candidate for future DG systems. This paper presents a controller design for a ZSI-based DG system to improve power quality of distribution systems. The proposed control method is tested with simulation results obtained using...

  5. Full spatially coherent multiturn ERL x-ray source (MARS) based on two linacs

    Science.gov (United States)

    Getmanov, Ya V.; Kulipanov, G. N.; Shevchenko, O. A.; Skrinsky, A. N.; Tribendis, A. G.; Volkov, V. N.; Vinokurov, N. A.

    2013-03-01

    Multiturn energy recovery linacs (ERL) looks very promising for making ERLs less expensive and more flexible, but have serious intrinsic problems. Today, only one multiturn ERL exists. This Novosibirsk ERL operates with four orbit recuperation scheme. The conception of Multiturn Accelerator-recuperator Radiation Source (MARS) was proposed in 1997 by G.N. Kulipanov, A.N. Skrinsky and N.A. Vinokurov. The use of the two-linac ERL (D. Douglas, 2001) makes multiturn operation much easier. The feasibility study for such ERL-based high brightness x-ray source is presented.

  6. WEB ENABLED OPEN SOURCE GIS BASED TOURIST INFORMATION SYSTEM FOR BHOPAL CITY

    OpenAIRE

    Sreejit S. Nair,; Katiyar, Dr. S. K.

    2011-01-01

    With GIS gaining its foot as a decision support system, its use is gaining relevance, but high cost of commercial GIS software hinders the growth. On the other hand the Free/Open Source Software (FOSS) has opened up a gateway for many budget restricted institutions & users to venture into GIS development. This research paper assesses the possibility of using Open Source GIS (OS GIS) based software’s to create a low cost GIS project and to publish the same over internet using free Web GIS soft...

  7. Red Tide Information Extraction Based on Multi-source Remote Sensing Data in Haizhou Bay

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to extract red tide information in Haizhou Bay on the basis of multi-source remote sensing data.[Method] Red tide in Haizhou Bay was studied based on multi-source remote sensing data,such as IRS-P6 data on October 8,2005,Landsat 5-TM data on May 20,2006,MODIS 1B data on October 6,2006 and HY-1B second-grade data on April 22,2009,which were firstly preprocessed through geometric correction,atmospheric correction,image resizing and so on.At the same time,the synchronous environment mon...

  8. Fast direction of arrival algorithm based on vector-sensor arrays using wideband sources

    Institute of Scientific and Technical Information of China (English)

    SUN Guo-cang; HUI Jun-ying; CHEN Yang

    2008-01-01

    An acoustic vector sensor (AVS) can capture more information than a conventional acoustic pressure sensor (APS). As a result, more output channels are required when multiple AVS are formed into arrays, making processing the data stream computationally intense. This paper proposes a new algorithm based on the propagator method for wideband coherent sources that eliminates eigen-decomposition in order to reduce the computational burden. Data from simulations and lake trials showed that the new algorithm is valid: it resolves coherent sources, breaks left/right ambiguity, and allows inter element spacing to exceed a half-wavelength.

  9. An accelerator-based epithermal photoneutron source for boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, H.E.

    1996-04-01

    Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10{sup 7} neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF{sub 3} composite and a stacked Al/Teflon design) at various incident electron energies.

  10. An emission source inversion model based on satellite data and its application in air quality forecasts

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper aims at constructing an emission source inversion model using a variational processing method and adaptive nudging scheme for the Community Multiscale Air Quality Model (CMAQ) based on satellite data to investigate the applicability of high resolution OMI (Ozone Monitoring Instrument) column concentration data for air quality forecasts over the North China. The results show a reasonable consistency and good correlation between the spatial distributions of NO2 from surface and OMI satellite measurements in both winter and summer. Such OMI products may be used to implement integrated variational analysis based on observation data on the ground. With linear and variational corrections made, the spatial distribution of OMI NO2 clearly revealed more localized distributing characteristics of NO2 concentration. With such information, emission sources in the southwest and southeast of North China are found to have greater impacts on air quality in Beijing. When the retrieved emission source inventory based on high-resolution OMI NO2 data was used, the coupled Weather Research Forecasting CMAQ model (WRF-CMAQ) performed significantly better in forecasting NO2 concentration level and its tendency as reflected by the more consistencies between the NO2 concentrations from surface observation and model result. In conclusion, satellite data are particularly important for simulating NO2 concentrations on urban and street-block scale. High-resolution OMI NO2 data are applicable for inversing NOx emission source inventory, assessing the regional pollution status and pollution control strategy, and improving the model forecasting results on urban scale.

  11. An accelerator-based epithermal photoneutron source for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 107 neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF3 composite and a stacked Al/Teflon design) at various incident electron energies

  12. Sediment sources in a small agricultural catchment: A composite fingerprinting approach based on the selection of potential sources

    Science.gov (United States)

    Zhou, Huiping; Chang, Weina; Zhang, Longjiang

    2016-08-01

    Fingerprinting techniques have been widely used as a reasonable and reliable means for investigating sediment sources, especially in relatively large catchments in which there are significant differences in surface materials. However, the discrimination power of fingerprint properties for small catchments, in which the surface materials are relatively homogeneous and human interference is marked, may be affected by fragmentary or confused source information. Using fingerprinting techniques can be difficult, and there is still a need for further studies to verify the effectiveness of such techniques in these small catchments. A composite fingerprinting approach was used in this study to investigate the main sources of sediment output, as well as their relative contributions, from a small catchment (30 km2) with high levels of farming and mining activities. The impact of the selection of different potential sediment sources on the derivation of composite fingerprints and its discrimination power were also investigated by comparing the results from different combinations of potential source types. The initial source types and several samples that could cause confusion were adjusted. These adjustments improved the discrimination power of the composite fingerprints. The results showed that the composite fingerprinting approach used in this study had a discriminatory efficiency of 89.2% for different sediment sources and that the model had a mean goodness of fit of 0.90. Cultivated lands were the main sediment source. The sediment contribution of the studied cultivated lands ranged from 39.9% to 87.8%, with a mean of 76.6%, for multiple deposited sediment samples. The mean contribution of woodlands was 21.7%. Overall, the sediment contribution from mining and road areas was relatively low. The selection of potential sources is an important factor in the application of fingerprinting techniques and warrants more attention in future studies, as is the case with other

  13. Multivariable Fuzzy Control Based Mobile Robot Odor Source Localization via Semitensor Product

    Directory of Open Access Journals (Sweden)

    Ping Jiang

    2015-01-01

    Full Text Available In order to take full advantage of the multisensor information, a MIMO fuzzy control system based on semitensor product (STP is set up for mobile robot odor source localization (OSL. Multisensor information, such as vision, olfaction, laser, wind speed, and direction, is the input of the fuzzy control system and the relative searching strategies, such as random searching (RS, nearest distance-based vision searching (NDVS, and odor source declaration (OSD, are the outputs. Fuzzy control rules with algebraic equations are given according to the multisensor information via STP. Any output can be updated in the proposed fuzzy control system and has no influence on the other searching strategies. The proposed MIMO fuzzy control scheme based on STP can reach the theoretical system of the mobile robot OSL. Experimental results show the efficiency of the proposed method.

  14. Overview of receptor-based source apportionment studies for speciated atmospheric mercury

    Science.gov (United States)

    Cheng, I.; Xu, X.; Zhang, L.

    2015-07-01

    Receptor-based source apportionment studies of speciated atmospheric mercury are not only concerned with source contributions but also with the influence of transport, transformation, and deposition processes on speciated atmospheric mercury concentrations at receptor locations. Previous studies applied multivariate receptor models including principal components analysis and positive matrix factorization, and back trajectory receptor models including potential source contribution function, gridded frequency distributions, and concentration-back trajectory models. Combustion sources (e.g., coal combustion, biomass burning, and vehicular, industrial and waste incineration emissions), crustal/soil dust, and chemical and physical processes, such as gaseous elemental mercury (GEM) oxidation reactions, boundary layer mixing, and GEM flux from surfaces were inferred from the multivariate studies, which were predominantly conducted at receptor sites in Canada and the US. Back trajectory receptor models revealed potential impacts of large industrial areas such as the Ohio River valley in the US and throughout China, metal smelters, mercury evasion from the ocean and the Great Lakes, and free troposphere transport on receptor measurements. Input data and model parameters specific to atmospheric mercury receptor models are summarized and model strengths and weaknesses are also discussed. Multivariate models are suitable for receptor locations with intensive air monitoring because they require long-term collocated and simultaneous measurements of speciated atmospheric Hg and ancillary pollutants. The multivariate models provide more insight about the types of Hg emission sources and Hg processes that could affect speciated atmospheric Hg at a receptor location, whereas back trajectory receptor models are mainly ideal for identifying potential regional Hg source locations impacting elevated Hg concentrations. Interpretation of the multivariate model output to sources can be

  15. Refined repetitive sequence searches utilizing a fast hash function and cross species information retrievals

    Directory of Open Access Journals (Sweden)

    Reneker Jeff

    2005-05-01

    Full Text Available Abstract Background Searching for small tandem/disperse repetitive DNA sequences streamlines many biomedical research processes. For instance, whole genomic array analysis in yeast has revealed 22 PHO-regulated genes. The promoter regions of all but one of them contain at least one of the two core Pho4p binding sites, CACGTG and CACGTT. In humans, microsatellites play a role in a number of rare neurodegenerative diseases such as spinocerebellar ataxia type 1 (SCA1. SCA1 is a hereditary neurodegenerative disease caused by an expanded CAG repeat in the coding sequence of the gene. In bacterial pathogens, microsatellites are proposed to regulate expression of some virulence factors. For example, bacteria commonly generate intra-strain diversity through phase variation which is strongly associated with virulence determinants. A recent analysis of the complete sequences of the Helicobacter pylori strains 26695 and J99 has identified 46 putative phase-variable genes among the two genomes through their association with homopolymeric tracts and dinucleotide repeats. Life scientists are increasingly interested in studying the function of small sequences of DNA. However, current search algorithms often generate thousands of matches – most of which are irrelevant to the researcher. Results We present our hash function as well as our search algorithm to locate small sequences of DNA within multiple genomes. Our system applies information retrieval algorithms to discover knowledge of cross-species conservation of repeat sequences. We discuss our incorporation of the Gene Ontology (GO database into these algorithms. We conduct an exhaustive time analysis of our system for various repetitive sequence lengths. For instance, a search for eight bases of sequence within 3.224 GBases on 49 different chromosomes takes 1.147 seconds on average. To illustrate the relevance of the search results, we conduct a search with and without added annotation terms for the

  16. Project-based physics labs using low-cost open-source hardware

    CERN Document Server

    Bouquet, F; Fuchs-Gallezot, M; Maurines, L

    2016-01-01

    We describe a project-based physics lab, which we proposed to third-year university students. Theses labs are based on new open-source low-cost equipment (Arduino microcontrollers and compatible sensors) which allows a complete autonomy for the students. The students develop their own experimental setup and study the physics topic of their choice. Based on the results obtained by the students and on various surveys, we discuss how these projects let the students discover the reality of experimental physics and how engaging these new tools are. Technical specifications of the acquisition material and case studies are also presented for practical implementation in other universities.

  17. Development of high-power picosecond fiber-based ultraviolet source

    OpenAIRE

    Canals Casals, Josep

    2014-01-01

    Treball final de màster oficial fet en col·laboració amb Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB) i Institut de Ciències Fotòniques (ICFO) [ANGLÈS] We report a high-power picosecond ultraviolet source at 266 nm in a compact design based on single-pass fourth harmonic generation and mode-locked Yb-fiber laser. The configuration has two stages: SHG of 1064 nm to 532 nm based on BIBO crystal followed by SHG of 532 nm to 266 nm based on BBO crystal. The obtained p...

  18. The Effect of Repetitive Passive and Active Movements on Proprioception Ability in Forearm Supination

    OpenAIRE

    Kwon, OhSung; Lee, Seungwon; Lee, Youngwoo; Seo, DongKwon; Jung, Sangwoo; Choi, Wonjae

    2013-01-01

    [Purpose] This study was conducted in order to investigate the effect of repetitive passive movement and repetitive active movement on proprioception in forearm supination. [Subjects] This study had a cross-sectional design. Twenty-three right-handed healthy subjects were recruited. All subjects randomly received both repetitive passive movement and repetitive active movement (repetitive passive/active movement at 120°/s with 60 repetitions over a 0–80° range). Active and passive joint reposi...

  19. New source-moderator geometry to improve performance of 252Cf and 241Am-Be source-based PGNAA setups

    International Nuclear Information System (INIS)

    The gamma ray yield from a 252Cf and a 241Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the 252Cf and the 241Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a 252Cf and a 241Am-Be source-based PGNAA setups

  20. New source-moderator geometry to improve performance of {sup 252}Cf and {sup 241}Am-Be source-based PGNAA setups

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)]. E-mail: aanaqvi@kfupm.edu.sa; Abdelmonem, M.S. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Misned, Ghada [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia); Al-Ghamdi, Hanan [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia)

    2006-06-15

    The gamma ray yield from a {sup 252}Cf and a {sup 241}Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the {sup 252}Cf and the {sup 241}Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a {sup 252}Cf and a {sup 241}Am-Be source-based PGNAA setups.