WorldWideScience

Sample records for broadband continuous spectra

  1. Broadband Eclipse Spectra of Exoplanets are Featureless

    CERN Document Server

    Hansen, C J; Cowan, N B

    2014-01-01

    Spectral retrieval methods leverage features in emission spectra to constrain the atmospheric composition and structure of transiting exoplanets. Most of the observed emission spectra consist of broadband photometric observations at a small number of wavelengths. We compare the Bayesian Information Criterion (BIC) of blackbody fits and spectral retrieval fits for all planets with eclipse measurements in multiple thermal wavebands, typically hot Jupiters with 2-4 observations. If the published error bars are taken at face value, then eight planets are significantly better fit by a spectral model than by a blackbody. In this under-constrained regime, however, photometric uncertainties directly impact one's ability to constrain atmospheric properties. By considering the handful of planets for which eclipse measurements have been repeated and/or reanalyzed, we obtain an empirical estimate of systematic uncertainties for broadband eclipse depths obtained with the Spitzer Space Telescope: sigma_sys = 5E-4. When thi...

  2. Broadband turbulent spectra in gamma-ray burst light curves

    Energy Technology Data Exchange (ETDEWEB)

    Van Putten, Maurice H. P. M. [Astronomy and Space Science, Sejong University, 98 Gunja-Dong Gwangin-gu, Seoul 143-747 (Korea, Republic of); Guidorzi, Cristiano; Frontera, Filippo, E-mail: mvp@sejong.ac.kr [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  3. 76 FR 23812 - Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects...

    Science.gov (United States)

    2011-04-28

    ... COMMISSION Reliability and Continuity of Communications Networks, Including Broadband Technologies; Effects on Broadband Communications Networks of Damage or Failure of Network Equipment or Severe Overload; Independent Panel Reviewing the Impact of Hurricane Katrina on Communications Networks AGENCY:...

  4. Effects of chirp of pump pulses on broadband terahertz pulse spectra generated by optical rectification

    Science.gov (United States)

    Hamazaki, Junichi; Furusawa, Kentaro; Sekine, Norihiko; Kasamatsu, Akifumi; Hosako, Iwao

    2016-11-01

    The effects of the chirp of the pump pulse in broadband terahertz (THz) pulse generation by optical rectification (OR) in GaP were systematically investigated. It was found that the pre-compensation for the dispersion of GaP is important for obtaining smooth and single-peaked THz spectra as well as high power-conversion efficiency. It was also found that an excessive amount of chirp leads to distortions in THz spectra, which can be quantitatively analyzed by using a simple model. Our results highlight the importance of accurate control over the chirp of the pump pulse for generating broadband THz pulses by OR.

  5. Generalised turbulence spectra for broadband noise predictions with the Random Particle Mesh method

    CERN Document Server

    Wohlbrandt, Attila; Guerin, Sebastien; Ewert, Roland

    2015-01-01

    For better comparison to fan broadband noise experiments the Random Particle Mesh (RPM) method is extended to generalised turbulence spectra. The RPM method synthesises turbulent fluctuations by filtering white noise with a Gaussian filter kernel, which in turn gives a Gaussian spectrum. The Gaussian function is smooth and its derivatives and antiderivatives are again Gaussian functions; the Gaussian filter is efficient and finds wide-spread applications in stochastic signal processing. However in many applications Gaussian spectra are not matching physical spectra. E.g. in turbo-machines, the von Karman, Liepmann, and modified von Karman spectra are the most relevant model spectra. In the current paper we show how to analytically derive weighting functions to realise arbitrary spectra which are isotropic and solenoidal using a superposition of weighted Gaussian spectra of differing length scales. The analytic weighting functions for the von Karman , the Liepmann , and the modified von Karman spectra are deri...

  6. Continuous Vernier filtering of an optical frequency comb for broadband cavity-enhanced molecular spectroscopy

    CERN Document Server

    Rutkowski, Lucile

    2016-01-01

    We have recently introduced the Vernier-based Direct Frequency Comb Cavity-Enhanced Spectroscopy technique and we present the corresponding formalism for quantitative broadband spectroscopy. We achieve high sensitivity and broadband performance by acquiring spectra covering more than 2000 cm$^{-1}$ around 12600 cm$^{-1}$ (800 nm), resolving the 3$\

  7. Sensitivity Limits of Deep Average Broadband Microwave and Mm-Wave Spectra

    Science.gov (United States)

    Muckle, Matt T.; Zaleski, Daniel P.; Steber, Amanda; Harris, Brent; Pate, Brooks H.

    2012-06-01

    High-speed digitizers have enabled the field of broadband molecular rotational spectroscopy at microwave-to-THz frequencies. Improvements in data throughput from these digitizers makes it feasible to perform deep averages (often more than 1 million time-domain averages of the free induction decay) to increase the measurement sensitivity. The use of broadband signal detection introduces new issues that are key for determining the practical sensitivity limits of these spectrometers. The practical limit on spectrometer sensitivity is often set by the number of spurious signals that are generated by the molecular signals themselves. For example, in cases where the molecular signals are down converted prior to digitization, the spectral purity of the local oscillator is crucial with spurious frequencies introducing spectral images. It is also possible to generate new local oscillator frequencies within the broadband mixers typically used in the broadband down conversion. A second issue it the potential for a vast number of intermodulation (IM) spurious signals resulting from the beating of two strong molecular transitions. This beat frequency can subsequently modulate all other molecular signals adding sidebands to all transitions at the beat frequency of the transition pair. This talk will summarize our experience with the spurious signal levels coming from these effects and the strategies we have adopted to minimize spurious signals in spectra where high sensitivity is necessary.

  8. Spectra of Nearby Galaxies Measured with a New Very Broadband Receiver

    CERN Document Server

    Narayanan, Gopal; Erickson, Neal R; Chung, Aeree; Heyer, Mark H; Yun, Min; Irvine, William M; 10.1017/S1743921308021698

    2008-01-01

    Three-millimeter-wavelength spectra of a number of nearby galaxies have been obtained at the Five College Radio Astronomy Observatory (FCRAO) using a new, very broadband receiver. This instrument, which we call the Redshift Search Receiver, has an instantaneous bandwidth of 36 GHz and operates from 74 to 110.5 GHz. The receiver has been built at UMass/FCRAO to be part of the initial instrumentation for the Large Millimeter Telescope (LMT) and is intended primarily for determination of the redshift of distant, dust-obscured galaxies. It is being tested on the FCRAO 14m by measuring the 3mm spectra of a number of nearby galaxies. There are interesting differences in the chemistry of these galaxies.

  9. The broadband microwave spectra of the monoterpenoids thymol and carvacrol: Conformational landscape and internal dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, D.; Shubert, V. A. [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); The Center for Free-Electron Laser Science, Hamburg (Germany); Giuliano, B. M. [Center for Astrobiology, INTA-CSIC, Torrejón de Ardoz, Madrid (Spain); Schnell, M., E-mail: melanie.schnell@mpsd.mpg.de [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); The Center for Free-Electron Laser Science, Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Hamburg (Germany)

    2014-07-21

    The rotational spectra of the monoterpenoids thymol and carvacrol are reported in the frequency range 2–8.5 GHz, obtained with broadband Fourier-transform microwave spectroscopy. For carvacrol four different conformations were identified in the cold conditions of the molecular jet, whereas only three conformations were observed for thymol. The rotational constants and other molecular parameters are reported and compared with quantum chemical calculations. For both molecules, line splittings due to methyl group internal rotation were observed and the resulting barrier heights could be determined. The experimental barrier heights, 4.0863(25) kJ/mol for trans-carvacrol-A, 4.4024(16) kJ/mol for trans-carvacrol-B, and 0.3699(11) kJ/mol for trans-thymol-A, are compared with similar molecules.

  10. The broadband microwave spectra of the monoterpenoids thymol and carvacrol: Conformational landscape and internal dynamics

    International Nuclear Information System (INIS)

    The rotational spectra of the monoterpenoids thymol and carvacrol are reported in the frequency range 2–8.5 GHz, obtained with broadband Fourier-transform microwave spectroscopy. For carvacrol four different conformations were identified in the cold conditions of the molecular jet, whereas only three conformations were observed for thymol. The rotational constants and other molecular parameters are reported and compared with quantum chemical calculations. For both molecules, line splittings due to methyl group internal rotation were observed and the resulting barrier heights could be determined. The experimental barrier heights, 4.0863(25) kJ/mol for trans-carvacrol-A, 4.4024(16) kJ/mol for trans-carvacrol-B, and 0.3699(11) kJ/mol for trans-thymol-A, are compared with similar molecules

  11. Energy corrections and persistent perturbation effects in continuous spectra

    NARCIS (Netherlands)

    Hove, Léon van

    1955-01-01

    The quantum-mechanical perturbation theory of continuous energy spectra is investigated for a special class of perturbations possessing some of the formal properties of the familiar interaction energies of field theory. These formal properties entail the inapplicability of the familiar perturbation

  12. An Application of the Coda Methodology for Moment-Rate Spectra Using Broadband Stations in Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Eken, T; Mayeda, K; Hofstetter, A; Gok, R; Orgulu, G; Turkelli, N

    2004-02-03

    A recently developed coda magnitude methodology was applied to selected broadband stations in Turkey for the purpose of testing the coda method in a large, laterally complex region. As found in other, albeit smaller regions, coda envelope amplitude measurements are significantly less variable than distance-corrected direct wave measurements (i.e., L{sub g} and surface waves) by roughly a factor 3-to-4. Despite strong lateral crustal heterogeneity in Turkey, we found that the region could be adequately modeled assuming a simple 1-D, radially symmetric path correction for 10 narrow frequency bands ranging between 0.02 to 2.0 Hz. For higher frequencies however, 2-D path corrections will be necessary and will be the subject of a future study. After calibrating the stations ISP, ISKB, and MALT for local and regional distances, single-station moment-magnitude estimates (M{sub w}) derived from the coda spectra were in excellent agreement with those determined from multi-station waveform modeling inversions of long-period data, exhibiting a data standard deviation of 0.17. Though the calibration was validated using large events, the results of the calibration will extend M{sub w} estimates to significantly smaller events which could not otherwise be waveform modeled due to poor signal-to-noise ratio at long periods and sparse station coverage. The successful application of the method is remarkable considering the significant lateral complexity in Turkey and the simple assumptions used in the coda method.

  13. An Application of the Coda Methodology for Moment-Rate Spectra Using Broadband Stations in Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Eken Tuna, Kevin Mayeda, Abraham Hofstetter, Rengin Gok, Gonca Orgulu, Niyazi Turkelli

    2004-07-11

    A recently developed coda magnitude methodology was applied to selected broadband stations in Turkey for the purpose of testing the coda method in a large, laterally complex region. As found in other, albeit smaller regions, coda envelope amplitude measurements are significantly less variable than distance-corrected direct wave measurements (i.e., L{sub g} and surface waves) by roughly a factor 3-to-4. Despite strong lateral crustal heterogeneity in Turkey, they found that the region could be adequately modeled assuming a simple 1-D, radially symmetric path correction. After calibrating the stations ISP, ISKB and MALT for local and regional distances, single-station moment-magnitude estimates (M{sub W}) derived from the coda spectra were in excellent agreement with those determined from multistation waveform modeling inversions, exhibiting a data standard deviation of 0.17. Though the calibration was validated using large events, the results of the calibration will extend M{sub W} estimates to significantly smaller events which could not otherwise be waveform modeled. The successful application of the method is remarkable considering the significant lateral complexity in Turkey and the simple assumptions used in the coda method.

  14. Broadband nature of power spectra for intermittent maps with summable and nonsummable decay of correlations

    Science.gov (United States)

    Gottwald, Georg A.; Melbourne, Ian

    2016-04-01

    We present results on the broadband nature of the power spectrum S(ω ), ω \\in (0,2π ), for a large class of nonuniformly expanding maps with summable and nonsummable decay of correlations. In particular, we consider a class of intermittent maps f :[0,1]\\to [0,1] with f(x)≈ {x}1+γ for x≈ 0, where γ \\in (0,1). Such maps have summable decay of correlations when γ \\in ≤ft(0,\\frac{1}{2}\\right), and S(ω ) extends to a continuous function on [0,2π ] by the classical Wiener-Khintchine theorem. We show that S(ω ) is typically bounded away from zero for Hölder observables. Moreover, in the nonsummable case γ \\in ≤ft[\\frac{1}{2},1\\right), we show that S(ω ) is defined almost everywhere with a continuous extension \\tilde{S}(ω ) defined on (0,2π ), and \\tilde{S}(ω ) is typically nonvanishing.

  15. Quasi-continuous metasurface for ultra-broadband and polarization-controlled electromagnetic beam deflection

    OpenAIRE

    Yanqin Wang; Mingbo Pu; Zuojun Zhang; Xiong Li; Xiaoliang Ma; Zeyu Zhao; Xiangang Luo

    2015-01-01

    Two-dimensional metasurface has attracted growing interest in recent years, owing to its ability in manipulating the phase, amplitude and polarization state of electromagnetic wave within a single interface. However, most existing metasurfaces rely on the collective responses of a set of discrete meta-atoms to perform various functionalities. In this paper, we presented a quasi-continuous metasurface for high-efficiency and broadband beam steering in the microwave regime. It is demonstrated b...

  16. Broadband conductivity spectra of fast-ion-conducting silver selenite glasses: Dependence on power law and scaling

    Science.gov (United States)

    Deb, B.; Bhattacharya, S.; Ghosh, A.

    2011-11-01

    In this letter we have studied broadband conductivity spectra (10 Hz-3 GHz) of fast-ion-conducting silver selenite glasses of compositions xAgI-(1-x)(yAg2O-(1-y)SeO2). We have observed that the conductivity spectra below 10 MHz are characterized by a power law with exponent less than unity, while the conductivity spectra in the high-frequency range (above 10 MHz) have been adequately explained in the framework of the unified site relaxation model with exponent greater than unity. The scaling of the conductivity spectra indicates that the time-temperature superposition principle is valid in the low-frequency regime, but not in the high-frequency regime.

  17. Quasi-continuous metasurface for ultra-broadband and polarization-controlled electromagnetic beam deflection

    Science.gov (United States)

    Wang, Yanqin; Pu, Mingbo; Zhang, Zuojun; Li, Xiong; Ma, Xiaoliang; Zhao, Zeyu; Luo, Xiangang

    2015-12-01

    Two-dimensional metasurface has attracted growing interest in recent years, owing to its ability in manipulating the phase, amplitude and polarization state of electromagnetic wave within a single interface. However, most existing metasurfaces rely on the collective responses of a set of discrete meta-atoms to perform various functionalities. In this paper, we presented a quasi-continuous metasurface for high-efficiency and broadband beam steering in the microwave regime. It is demonstrated both in simulation and experiment that the incident beam deviates from the normal direction after transmitting through the ultrathin metasurface. The efficiency of the proposed metasurface approximates to the theoretical limit of the single-layer metasurface in a broad frequency range, owing to the elimination of the circuit resonance in traditional discrete structures. The proposed scheme promises potential applications in broadband electromagnetic modulation and communication systems, etc.

  18. Quasi-continuous metasurface for ultra-broadband and polarization-controlled electromagnetic beam deflection

    Science.gov (United States)

    Wang, Yanqin; Pu, Mingbo; Zhang, Zuojun; Li, Xiong; Ma, Xiaoliang; Zhao, Zeyu; Luo, Xiangang

    2015-01-01

    Two-dimensional metasurface has attracted growing interest in recent years, owing to its ability in manipulating the phase, amplitude and polarization state of electromagnetic wave within a single interface. However, most existing metasurfaces rely on the collective responses of a set of discrete meta-atoms to perform various functionalities. In this paper, we presented a quasi-continuous metasurface for high-efficiency and broadband beam steering in the microwave regime. It is demonstrated both in simulation and experiment that the incident beam deviates from the normal direction after transmitting through the ultrathin metasurface. The efficiency of the proposed metasurface approximates to the theoretical limit of the single-layer metasurface in a broad frequency range, owing to the elimination of the circuit resonance in traditional discrete structures. The proposed scheme promises potential applications in broadband electromagnetic modulation and communication systems, etc. PMID:26635228

  19. BROADBAND EMISSION SPECTRA FROM THE CYGNUS X-3 JET IN THE SOFT SPECTRAL STATE

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian-Fu; Lu, Ju-Fu, E-mail: jianfuzhang.yn@gmail.com, E-mail: lujf@xmu.edu.cn [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China)

    2015-02-01

    In order to understand the main observational characteristics of the Galactic X-ray binary Cygnus X-3, we propose a radiation model in which high-energy electrons accelerate in the dissipation zone of a jet and produce nonthermal broadband emissions. Broadband spectral energy distributions are computed to compare the AGILE and Fermi LAT data with the multi-band data during soft X-ray spectral states. By fitting observations at different locations of the jet, we find that the emission region is rather compact and should be located at a distance of about one orbital radius. Our results can explain the current multi-frequency observations and also predict the TeV band emission. The model could be tested by a polarization measurement at IR band, and/or by a correlation study between the GeV and TeV bands once very-high-energy observations are available.

  20. Determination of the chemical parameters and manufacturer of divins from their broadband transmission spectra

    Science.gov (United States)

    Khodasevich, M. A.; Sinitsyn, G. V.; Skorbanova, E. A.; Rogovaya, M. V.; Kambur, E. I.; Aseev, V. A.

    2016-06-01

    Analysis of multiparametric data on transmission spectra of 24 divins (Moldovan cognacs) in the 190-2600 nm range allows identification of outliers and their removal from a sample under study in the following consideration. The principal component analysis and classification tree with a single-rank predictor constructed in the 2D space of principal components allow classification of divin manufacturers. It is shown that the accuracy of syringaldehyde, ethyl acetate, vanillin, and gallic acid concentrations in divins calculated with the regression to latent structures depends on the sample volume and is 3, 6, 16, and 20%, respectively, which is acceptable for the application.

  1. X-Ray Emitting GHz-Peaked Spectrum Galaxies: Testing a Dynamical-Radiative Model with Broad-Band Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Ostorero, L.; /Turin U. /INFN, Turin; Moderski, R.; /Warsaw, Copernicus Astron. Ctr. /KIPAC, Menlo Park; Stawarz, L.; /KIPAC, Menlo Park /Jagiellonian U., Astron. Observ.; Diaferio, A.; /Turin U. /INFN, Turin; Kowalska, I.; /Warsaw U. Observ.; Cheung, C.C.; /NASA, Goddard /Naval Research Lab, Wash., D.C.; Kataoka, J.; /Waseda U., RISE; Begelman, M.C.; /JILA, Boulder; Wagner, S.J.; /Heidelberg Observ.

    2010-06-07

    In a dynamical-radiative model we recently developed to describe the physics of compact, GHz-Peaked-Spectrum (GPS) sources, the relativistic jets propagate across the inner, kpc-sized region of the host galaxy, while the electron population of the expanding lobes evolves and emits synchrotron and inverse-Compton (IC) radiation. Interstellar-medium gas clouds engulfed by the expanding lobes, and photoionized by the active nucleus, are responsible for the radio spectral turnover through free-free absorption (FFA) of the synchrotron photons. The model provides a description of the evolution of the GPS spectral energy distribution (SED) with the source expansion, predicting significant and complex high-energy emission, from the X-ray to the {gamma}-ray frequency domain. Here, we test this model with the broad-band SEDs of a sample of eleven X-ray emitting GPS galaxies with Compact-Symmetric-Object (CSO) morphology, and show that: (i) the shape of the radio continuum at frequencies lower than the spectral turnover is indeed well accounted for by the FFA mechanism; (ii) the observed X-ray spectra can be interpreted as non-thermal radiation produced via IC scattering of the local radiation fields off the lobe particles, providing a viable alternative to the thermal, accretion-disk dominated scenario. We also show that the relation between the hydrogen column densities derived from the X-ray (N{sub H}) and radio (N{sub HI}) data of the sources is suggestive of a positive correlation, which, if confirmed by future observations, would provide further support to our scenario of high-energy emitting lobes.

  2. Spectra of geometric operators in three-dimensional loop quantum gravity: From discrete to continuous

    Science.gov (United States)

    Achour, Jibril Ben; Geiller, Marc; Noui, Karim; Yu, Chao

    2014-03-01

    We study and compare the spectra of geometric operators (length and area) in the quantum kinematics of two formulations of three-dimensional Lorentzian loop quantum gravity. In the SU(2) Ashtekar-Barbero framework, the spectra are discrete and depend on the Barbero-Immirzi parameter γ exactly like in the four-dimensional case. However, we show that when working with the self-dual variables and imposing the reality conditions the spectra become continuous and γ independent.

  3. Flow angle dependent photoacoustic Doppler power spectra under intensity-modulated continuous wave laser excitation

    Directory of Open Access Journals (Sweden)

    Yu Tong

    2016-02-01

    Full Text Available Photoacoustic Doppler (PAD power spectra showing an evident Doppler shift represent the major characteristics of the continuous wave-excited or burst wave-excited versions of PAD flow measurements. In this paper, the flow angle dependences of the PAD power spectra are investigated using an experiment setup that was established based on intensity-modulated continuous wave laser excitation. The setup has an overall configuration that is similar to a previously reported configuration, but is more sophisticated in that it accurately aligns the laser illumination with the ultrasound detection process, and in that it picks up the correct sample position. In the analysis of the power spectra data, we find that the background power spectra can be extracted by combining the output signals from the two channels of the lock-in amplifier, which is very useful for identification of the PAD power spectra. The power spectra are presented and analyzed in opposite flow directions, at different flow speeds, and at different flow angles. The power spectra at a 90° flow angle show the unique properties of symmetrical shapes due to PAD broadening. For the other flow angles, the smoothed power spectra clearly show a flow angle cosine relationship.

  4. On the relation between tonal and broadband content of hull pressure spectra due to cavitating ship propellers

    Science.gov (United States)

    Bosschers, J.

    2015-12-01

    Cavitating propellers generate pressure fluctuations on the hull of the ship. These pressure fluctuations are usually analyzed in the frequency domain using FFTs and the spectrum is composed of tonals at multiples of the blade passage frequency and a broadband part. The two are often considered separately but a relation between the two exists which has been investigated by theoretical signal analysis. It will be shown that the broadband part is related to the variability of the signal between blade passages and a simple procedure is proposed to quantify the variability in terms of amplitude and phase angle. The procedure has been applied to a data set obtained at sea trials.

  5. Spectra of stable sonoluminescence

    OpenAIRE

    Lewia, Stephen D.

    1992-01-01

    Approved for public release; distribution is unlimited The continuous emission of picosecond pulses of light has been observed to originate from a bubble trapped at the pressure antinode of a resonant sound field in water and in water/glycerin mixtures. The spectra of this light in several solutions has been measured with a scanning monochrometer/photomultiplier detector system. The spectra are broadband and show strong emission in the UV region. A comparison of this measurement to two ...

  6. The Broadband XMM-Newton and NuSTAR X-Ray Spectra of Two Ultraluminous X-Ray Sources in the Galaxy IC 342

    Science.gov (United States)

    Rana, Vikram; Harrison, Fiona A.; Bachetti, Matteo; Walton, Dominic J.; Furst, Felix; Barret, Didier; Miller, Jon M.; Fabian, Andrew C.; Boggs, Steven E.; Christensen, Finn C.; Craig, William W.; Grefenstette, Brian W.; Hailey, Charles J.; Madsen, Kristin K.; Ptak, Andrew F.; Stern, Daniel; Webb, Natalie A.; Zhang, William W.

    2015-02-01

    We present results for two ultraluminous X-ray sources (ULXs), IC 342 X-1 and IC 342 X-2, using two epochs of XMM-Newton and NuSTAR observations separated by ~7 days. We observe little spectral or flux variability above 1 keV between epochs, with unabsorbed 0.3-30 keV luminosities being 1.04+0.08-0.06 × 1040 erg s-1 for IC 342 X-1 and 7.40 ± 0.20 × 1039 erg s-1 for IC 342 X-2, so that both were observed in a similar, luminous state. Both sources have a high absorbing column in excess of the Galactic value. Neither source has a spectrum consistent with a black hole binary in low/hard state, and both ULXs exhibit strong curvature in their broadband X-ray spectra. This curvature rules out models that invoke a simple reflection-dominated spectrum with a broadened iron line and no cutoff in the illuminating power-law continuum. X-ray spectrum of IC 342 X-1 can be characterized by a soft disk-like blackbody component at low energies and a cool, optically thick Comptonization continuum at high energies, but unique physical interpretation of the spectral components remains challenging. The broadband spectrum of IC 342 X-2 can be fit by either a hot (3.8 keV) accretion disk or a Comptonized continuum with no indication of a seed photon population. Although the seed photon component may be masked by soft excess emission unlikely to be associated with the binary system, combined with the high absorption column, it is more plausible that the broadband X-ray emission arises from a simple thin blackbody disk component. Secure identification of the origin of the spectral components in these sources will likely require broadband spectral variability studies.

  7. An iterative method in a probabilistic approach to the spectral inverse problem: Differential emission measure from line spectra and broadband data

    CERN Document Server

    Goryaev, F F; Urnov, A M; Oparin, S N; Hochedez, J -F; Reale, F; 10.1051/0004-6361/201014280

    2010-01-01

    Inverse problems are of great importance in astrophysics for deriving information about the physical characteristics of hot optically thin plasma sources from their EUV and X-ray spectra. We describe and test an iterative method developed within the framework of a probabilistic approach to the spectral inverse problem for determining the thermal structures of the emitting plasma. We also demonstrate applications of this method to both high resolution line spectra and broadband imaging data. Our so-called Bayesian iterative method (BIM) is an iterative procedure based on Bayes' theorem and is used to reconstruct differential emission measure (DEM) distributions. To demonstrate the abilities of the BIM, we performed various numerical tests and model simulations establishing its robustness and usefulness. We then applied the BIM to observable data for several active regions (AR) previously analyzed with other DEM diagnostic techniques: both SUMER/SOHO (Landi and Feldman, 2008) and SPIRIT/CORONAS-F (Shestov et al...

  8. The Broadband XMM-Newton and NuSTAR X-ray Spectra of Two Ultraluminous X-ray Sources in the Galaxy IC 342

    DEFF Research Database (Denmark)

    Rana, Vikram; Harrison, Fiona A.; Bachetti, Matteo;

    2015-01-01

    We present results for two Ultraluminous X-ray Sources (ULXs), IC 342 X-1 and IC 342 X-2, using two epochs of XMM-Newton and NuSTAR observations separated by ∼7 days. We observe little spectral or flux variability above 1 keV between epochs, with unabsorbed 0.3-30 keV luminosities being $1...... ULXs exhibit strong curvature in their broadband X-ray spectra. This curvature rules out models that invoke a simple reflection-dominated spectrum with a broadened iron line and no cutoff in the illuminating power-law continuum. X-ray spectrum of IC 342 X-1 can be characterized by a soft disk......-like black body component at low energies and a cool, optically thick Comptonization continuum at high energies, but unique physical interpretation of the spectral components remains challenging. The broadband spectrum of IC 342 X-2 can be fit by either a hot (3.8 keV) accretion disk, or a Comptonized...

  9. THE BROADBAND XMM-NEWTON AND NuSTAR X-RAY SPECTRA OF TWO ULTRALUMINOUS X-RAY SOURCES IN THE GALAXY IC 342

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Vikram; Harrison, Fiona A.; Walton, Dominic J.; Furst, Felix; Grefenstette, Brian W.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Bachetti, Matteo; Barret, Didier; Webb, Natalie A. [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Miller, Jon M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Fabian, Andrew C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn C. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Ptak, Andrew F.; Zhang, William W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2015-02-01

    We present results for two ultraluminous X-ray sources (ULXs), IC 342 X-1 and IC 342 X-2, using two epochs of XMM-Newton and NuSTAR observations separated by ∼7 days. We observe little spectral or flux variability above 1 keV between epochs, with unabsorbed 0.3-30 keV luminosities being 1.04{sub −0.06}{sup +0.08}×10{sup 40} erg s{sup –1} for IC 342 X-1 and 7.40 ± 0.20 × 10{sup 39} erg s{sup –1} for IC 342 X-2, so that both were observed in a similar, luminous state. Both sources have a high absorbing column in excess of the Galactic value. Neither source has a spectrum consistent with a black hole binary in low/hard state, and both ULXs exhibit strong curvature in their broadband X-ray spectra. This curvature rules out models that invoke a simple reflection-dominated spectrum with a broadened iron line and no cutoff in the illuminating power-law continuum. X-ray spectrum of IC 342 X-1 can be characterized by a soft disk-like blackbody component at low energies and a cool, optically thick Comptonization continuum at high energies, but unique physical interpretation of the spectral components remains challenging. The broadband spectrum of IC 342 X-2 can be fit by either a hot (3.8 keV) accretion disk or a Comptonized continuum with no indication of a seed photon population. Although the seed photon component may be masked by soft excess emission unlikely to be associated with the binary system, combined with the high absorption column, it is more plausible that the broadband X-ray emission arises from a simple thin blackbody disk component. Secure identification of the origin of the spectral components in these sources will likely require broadband spectral variability studies.

  10. Broadband Continuous-Wave Multi-Harmonic Optical Comb Based on a Frequency Division-by-Three Optical Parametric Oscillator

    Directory of Open Access Journals (Sweden)

    Yen-Yin Lin

    2014-11-01

    Full Text Available We report a multi-watt broadband continuous-wave multi-harmonic optical comb based on a frequency division-by-three singly-resonant optical parametric oscillator. This cw optical comb is frequency-stabilized with the help of a beat signal derived from the signal and frequency-doubled idler waves. The measured frequency fluctuation in one standard deviation is ~437 kHz. This is comparable to the linewidth of the pump laser which is a master-oscillator seeded Yb:doped fiber amplifier at ~1064 nm. The measured powers of the fundamental wave and the harmonic waves up to the 6th harmonic wave are 1.64 W, 0.77 W, 3.9 W, 0.78 W, 0.17 W, and 0.11 W, respectively. The total spectral width covered by this multi-harmonic comb is ~470 THz. When properly phased, this multi-harmonic optical comb can be expected to produce by Fourier synthesis a light source consisting of periodic optical field waveforms that have an envelope full-width at half-maximum of 1.59 fs in each period.

  11. Challenges in noise removal from Doppler spectra acquired by a continuous-wave lidar

    DEFF Research Database (Denmark)

    Angelou, Nikolas; Foroughi Abari, Farzad; Mann, Jakob;

    2012-01-01

    This paper is focused on the required post processing of Doppler spectra, acquired from a continuous-wave coherent lidar at high sampling rates (400 Hz) and under rapid scanning of the laser beam. In particular, the necessary steps followed for extracting the wind speed from such Doppler spectra...... are presented. A method for determining the background noise spectrum without interrupting the transmission of the laser beam is described. Moreover, the dependency between the determination of the threshold of a Doppler spectrum with low signal-to-noise ratios and the characteristics of the wind flow...... are investigated and a systematic approach for removing the noise is outlined. The suggested post processing procedures are applied to two sample time series acquired by a short-range WindScanner during one second each....

  12. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    Institute of Scientific and Technical Information of China (English)

    Yin Jun; Yu Ling-Yao; Liu Xing; Wan Hui; Lin Zi-Yang; Niu Han-Ben

    2011-01-01

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of verious molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactious in the fields of biology, chemistry and naterial science.

  13. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    International Nuclear Information System (INIS)

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  14. Source Parameters and Crustal Attenuation in Interior Alaska: Estimates Using Broadband Lg-Wave Spectra Derived from the BEAAR Experiment Data.

    Science.gov (United States)

    Marriott, D. A.; Hansen, R. A.

    2002-12-01

    Source parameters, site effects, and regional crustal attenuation in interior Alaska were estimated using displacement amplitude spectra of Lg phase arrivals derived from the Broadband Experiment Across the Alaska Range (BEAAR) seismic data. The BEAAR project consisted of 36 three component broadband seismometers temporarily installed across the Alaska Range. This array stretched across a large portion of interior Alaska, providing excellent recordings of regional events. The model parameters were estimated using a simultaneous nonlinear least squares inversion including all the spectral data. The source parameters estimated were the seismic moment, Mo, and the corner frequency, fo, for each event. The values of Mo were well constrained and yielded an empirical relationship between ML and Mo for interior Alaska. Estimates of the corner frequency for each event, along with the Mo values, yielded an estimate of stress drop for each event. For events larger then ML = 3 in Alaska, stress drop showed no significant dependence on magnitude. A frequency dependent local site amplification term was estimated for each station in the inversion as an average of the residuals for each station over many events. The inclusion of this site term reduced the total residuals of the regional attenuation model calculations. A preliminary model for regional attenuation of the Lg seismic phase averaged over all tectonic regions across continental Alaska from BEAAR data was derived to be: QLg(f) = 166f0.58. This model was estimated from 123 shallow earthquakes larger than M =3 located in continental Alaska, and more than 1,000 spectra. Because the Lg phase was trapped in the crustal wave-guide, QLg gave a good representation of attenuation in the crust, and appears to correlate with crustal structure. Estimates of attenuation for each ray path show local variation in QLg. This variation may be caused by changes in crustal structure such as faulting, deformation, or differences in

  15. Virial Black Hole Mass Estimates for 280,000 AGNs from the SDSS Broad-Band Photometry and Single Epoch Spectra

    CERN Document Server

    Kozłowski, Szymon

    2016-01-01

    We use the Sloan Digital Sky Survey (SDSS) Quasar Data Release 12 (DR12Q), containing nearly 300,000 AGNs, to calculate the monochromatic luminosities at 5100\\AA, 3000\\AA, and 1350\\AA, derived from the broad-band extinction-corrected SDSS magnitudes. After matching them to their counterparts based on spectra and published in the SDSS Quasar Data Release 7 (DR7Q), we find perfect correlations with minute mean offsets ($\\sim$0.01 dex) and dispersions of differences of 0.11, 0.10, 0.12 dex, respectively, across a 2.5 dex luminosity range. We then estimate the active galactic nuclei (AGNs) black hole masses using the broad line region radius--luminosity relations and the FWHM of the MgII and CIV emission lines, to provide a catalog of 283,032 virial black hole mass estimates (132,451 for MgII, 213,068 for CIV, and 62,487 for both) along with the bolometric luminosity and the Eddington ratio estimates for $0.1

  16. Synthesis of Fourier holograms for recognition of radiation sources with continuous spectra by dispersive correlators

    Science.gov (United States)

    Molodtsov, D. Y.; Rodin, V. G.; Starikov, S. N.

    2015-05-01

    Dispersive correlators have been proposed previously for solving problems of recognition of radiating objects in real time. Correlation signals are formed by radiation of analyzed object during its interaction with spatial filter. Most difficult recognition case is when spectrum of input radiation is continuous (non-line spectrum). Method of synthesis of Fourier holograms for their using in dispersive correlators as spatial filters is developed in this work. Spectral ranges, in which values of components of radiation are greater than predetermined threshold for reference spectrum, were determined. Entrance slit used as reference object. Next, spatial image of spectrum, which is a set of images of object (slit), was formed. Amount of object images and its sizes are determined with selected wavelength ranges. Fourier hologram of this image was computer synthesized and had 2048x2048 pixels. Then this hologram was binarized and printed using laser imagesetter with 100 dots/mm resolution. In this work the scheme of the dispersive correlator with single Fourier-objective was used. Correlation signals for different spectra were experimentally formed. LEDs, including RGB-LED with ability of dynamically changing of composition of radiation spectrum, were used as radiation sources. Post-processing operations, which provide independence of recognition results from radiation source power and holograms diffraction efficiency, were defined. Three methods of normalization of correlation signal for identification signal obtaining were experimentally tested and compared. These methods are normalization to radiation power in zero, first, and both of these diffraction orders. Experimental results on identification of test sources with non-line radiation spectra are obtained. They show successful recognition of used LED sources of different colors. Average ratio of spectra coincidence signal to mismatch signal was 4.6 at relative spectral resolution of used setup equaled to 0.004.

  17. Research on the fiber dispersion and compensation in large-scale high-resolution broadband frequency-modulated continuous wave laser measurement system

    Science.gov (United States)

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

    2015-07-01

    The influence of a fiber dispersion calibration interferometer on the measurement results for a large-scale high-resolution broadband frequency-modulated continuous wave (FMCW) measurement system was studied. A model was constructed to simulate the influences of fiber dispersion on the measurements when using a frequency sampling method that corrects the tuning nonlinearity. The results indicated that a broadband external cavity tunable laser, in comparison with a semiconductor laser, causes linear variations in the measurement results because of the effect of the fiber dispersion in the calibration interference path for large-scale high-resolution measurements, and these variations decreased the resolution of the measurements. A method that combines chirp slope calibration and phase compensation to reduce the effects of the fiber dispersion was proposed. A gauge block with a height difference of 200 μm at a distance of 2.43 m was measured during the experiments. Before calibrating the fiber dispersion, the frequency spectrum showed false peaks, and it was difficult to distinguish the peaks of the targets. After compensating for the dispersion, the peaks of the targets could be clearly distinguished, and a height difference of 199.6 μm was measured. Using this model and the method to compensate for the dispersion will provide a reference for large-scale high-resolution broadband FMCW laser measurements.

  18. Constraining Lorentz invariance violation from the continuous spectra of short gamma-ray bursts

    Science.gov (United States)

    Chang, Zhe; Li, Xin; Lin, Hai-Nan; Sang, Yu; Wang, Ping; Wang, Sai

    2016-04-01

    In some quantum gravity theories, a foamy structure of space-time may lead to Lorentz invariance violation (LIV). As the most energetic explosions in the Universe, gamma-ray bursts (GRBs) provide an effect way to probe quantum gravity effects. In this paper, we use the continuous spectra of 20 short GRBs detected by the Swift satellite to give a conservative lower limit of quantum gravity energy scale M QG. Due to the LIV effect, photons with different energy have different velocities. This will lead to the delayed arrival of high energy photons relative to low energy ones. Based on the fact that the LIV-induced time delay cannot be longer than the duration of a GRB, we present the most conservative estimate of the quantum gravity energy scales from 20 short GRBs. The strictest constraint, M QG > 5.05 × 1014 GeV in the linearly corrected case, is from GRB 140622A. Our constraint on M QG, although not as tight as previous results, is the safest and most reliable so far. Supported by National Natural Science Foundation of China (11375203, 11305181, 11322545, 11335012) and Knowledge Innovation Program of The Chinese Academy of Sciences

  19. Detector system with high time resolution for the continuous measurement of spectra in the vacuum ultraviolet wavelength range

    OpenAIRE

    Biel, W.; Bertschinger, G.

    2004-01-01

    A new detector system with high time resolution (1 ms) has been developed and applied for the continuous measurement of spectra in the vacuum ultraviolet (VUV) and extreme ultraviolet (EUV) wavelength region at the fusion plasma experiment Torus Experiment for Technology-Oriented Research (TEXTOR). The system consists of an open multichannel-plate (MCP) detector with subsequent first generation (Gen I) light amplifier and a camera head which is based on a linear photodiode array with 1024 ele...

  20. Broadband transmission EPR spectroscopy.

    Directory of Open Access Journals (Sweden)

    Wilfred R Hagen

    Full Text Available EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9-10 GHz range. Most (biomolecular EPR spectra are determined by a combination of the frequency-dependent electronic Zeeman interaction and a number of frequency-independent interactions, notably, electron spin - nuclear spin interactions and electron spin - electron spin interactions, and unambiguous analysis requires data collection at different frequencies. Extant and long-standing practice is to use a different spectrometer for each frequency. We explore the alternative of replacing the narrow-band source plus single-mode resonator with a continuously tunable microwave source plus a non-resonant coaxial transmission cell in an unmodulated external field. Our source is an arbitrary wave digital signal generator producing an amplitude-modulated sinusoidal microwave in combination with a broadband amplifier for 0.8-2.7 GHz. Theory is developed for coaxial transmission with EPR detection as a function of cell dimensions and materials. We explore examples of a doublet system, a high-spin system, and an integer-spin system. Long, straigth, helical, and helico-toroidal cells are developed and tested with dilute aqueous solutions of spin label hydroxy-tempo. A detection limit of circa 5 µM HO-tempo in water at 800 MHz is obtained for the present setup, and possibilities for future improvement are discussed.

  1. Discretization of Continuous Time Discrete Scale Invariant Processes: Estimation and Spectra

    Science.gov (United States)

    Rezakhah, Saeid; Maleki, Yasaman

    2016-07-01

    Imposing some flexible sampling scheme we provide some discretization of continuous time discrete scale invariant (DSI) processes which is a subsidiary discrete time DSI process. Then by introducing some simple random measure we provide a second continuous time DSI process which provides a proper approximation of the first one. This enables us to provide a bilateral relation between covariance functions of the subsidiary process and the new continuous time processes. The time varying spectral representation of such continuous time DSI process is characterized, and its spectrum is estimated. Also, a new method for estimation time dependent Hurst parameter of such processes is provided which gives a more accurate estimation. The performance of this estimation method is studied via simulation. Finally this method is applied to the real data of S & P500 and Dow Jones indices for some special periods.

  2. The quantum emission spectra of rapidly-rotating Kerr black holes: Discrete or continuous?

    Directory of Open Access Journals (Sweden)

    Shahar Hod

    2015-10-01

    Full Text Available Bekenstein and Mukhanov (BM have suggested that, in a quantum theory of gravity, black holes may have discrete emission spectra. Using the time-energy uncertainty principle they have also shown that, for a (non-rotating Schwarzschild black hole, the natural broadening δω of the black-hole emission lines is expected to be small on the scale set by the characteristic frequency spacing Δω of the spectral lines: ζSch≡δω/Δω≪1. BM have therefore concluded that the expected discrete emission lines of the quantized Schwarzschild black hole are unlikely to overlap. In this paper we calculate the characteristic dimensionless ratio ζ(a¯≡δω/Δω for the predicted BM emission spectra of rapidly-rotating Kerr black holes (here a¯≡J/M2 is the dimensionless angular momentum of the black hole. It is shown that ζ(a¯ is an increasing function of the black-hole angular momentum. In particular, we find that the quantum emission lines of Kerr black holes in the regime a¯≳0.9 are characterized by the dimensionless ratio ζ(a¯≳1 and are therefore effectively blended together. Our results thus suggest that, even if the underlying mass (energy spectrum of these rapidly-rotating Kerr black holes is fundamentally discrete as suggested by Bekenstein and Mukhanov, the natural broadening phenomenon (associated with the time-energy uncertainty principle is expected to smear the black-hole radiation spectrum into a continuum.

  3. Optical coherence photoacoustic microscopy (OC-PAM) with an intensity-modulated continuous-wave broadband light source

    Science.gov (United States)

    Liu, Xiaojing; Wen, Rong; Li, Yiwen; Jiao, Shuliang

    2016-06-01

    We developed an optical coherence photoacoustic microscopy system using an intensity-modulated continuous-wave superluminescent diode with a center wavelength of 840 nm. The system can accomplish optical coherence tomography (OCT) and photoacoustic microscopy (PAM) simultaneously. Compared to the system with a pulsed light source, this system is able to achieve OCT imaging with quality as high as conventional spectral-domain OCT. Since both of the OCT and PAM images are generated from the same group of photons, they are intrinsically registered in the lateral directions. The system was tested for multimodal imaging the vasculature of mouse ear in vivo by using gold nanorods as contrast agent for PAM, as well as excised porcine eyes ex vivo. The OCT and PAM images showed complimentary information of the sample.

  4. Detector system with high time resolution for the continuous measurement of spectra in the vacuum ultraviolet wavelength range

    Science.gov (United States)

    Biel, W.; Bertschinger, G.

    2004-07-01

    A new detector system with high time resolution (1 ms) has been developed and applied for the continuous measurement of spectra in the vacuum ultraviolet (VUV) and extreme ultraviolet (EUV) wavelength region at the fusion plasma experiment Torus Experiment for Technology-Oriented Research (TEXTOR). The system consists of an open multichannel-plate (MCP) detector with subsequent first generation (Gen I) light amplifier and a camera head which is based on a linear photodiode array with 1024 elements (pixels). The camera head provides the output signals of the individual pixels sequentially as an analog voltage with a full spectra rate of 1000 per second, which are measured using a PC-based data acquisition system. Three vacuum spectrometers operating in the VUV/EUV region (10-130 nm) have been equipped with the new system and a successful campaign of measurements from about 4000 discharges at TEXTOR has been performed. Spectra are recorded with a usable linear dynamic range of 10 bit and a wavelength resolution corresponding to a width of 3-4 pixels.

  5. Theory of two-atom coherence in gases. II. Continuous-wave spectra

    Science.gov (United States)

    Ben-Reuven, Abraham

    1980-12-01

    General expressions are derived for the spectral line shapes of resonance absorption and scattering of coherent radiation in collision-broadened gases, taking into account effects of coherent excitation of two or more atoms (or molecules), as steady-state solutions of a hierarchy of master equations described in a previous publication (paper I). Coupling between the coherent motions of the atoms, provided by a Bethe-Salpeter-type effective interaction, in the binary-collision approximation, forms the essential mechanism for introducing cooperative coherent effects into the steady-state spectra. Explicit expressions are given for the effects of two-atom coherence in the binary-collision approximation, in which the Bloch-type dressed-atom self-energy superoperator is modified by the presence of collisions in which both atoms retain memory of their coherent propagation before the collision. The self-energies include the effects of resonance exchange symmetrization in self-broadening, and are renormalized by the coincidence of radiative transitions during the collisions. The impact (near-resonance) and the quasistatic (line-wing) limits of the applied-frequency detunings are discussed. In the quasistatic limit, coherent many-atom excitations become irrelevant; however, interactions of both collision partners with the radiation during the collision accounts for such phenomena as collision-induced absorption or radiative collisions. In the impact limit, the inclusion of the Bethe-Salpeter interactions allows for the appearance of two-atom resonances. Magnitude estimates of these effects are discussed. Effects of higher-rank (many-body) coherences are formally discussed with the help of a diagrammatic method, leading into implicit bootstrap equations that can be solved by iterative or other procedures.

  6. Broadband terahertz spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Wenhui Fan

    2011-01-01

    1.Introduction Spanning the frequency range between the infrared (IR) radiation and microwaves,terahertz (THz) waves are,also known as T-rays,T-lux,or simply called THz,assigned to cover the electromagnetic spectrum typically from 100 GHz (1011 Hz) to 10 THz (1013 Hz),namely,from 3 mm to 30 μm in wavelength,although slightly different definitions have been quoted by different authors.For a very long time,THz region is an almost unexplored field due to its rather unique location in the electromagnetic spectrum.Well-known techniques in optical or microwave region can not be directly employed in the THz range because optical wavelengths are too short and microwave wavelengths are too long compared to THz wavelengths.%An overview of the major techniques to generate and detect THz radiation so far, especially the major approaches to generate and detect coherent ultra-short THz pulses using ultra-short pulsed laser, has been presented. And also, this paper, in particularly, focuses on broadband THz spectroscopy and addresses on a number of issues relevant to generation and detection of broadband pulsed THz radiation as well as broadband time-domain THz spectroscopy (THz-TDS) with the help of ultra-short pulsed laser. The time-domain waveforms of coherent ultra-short THz pulses from photoconductive antenna excited by femtosecond laser with different pulse durations and their corresponding Fourier-transformed spectra have been obtained via the numerical simulation of ultrafast dynamics between femtosecond laser pulse and photoconductive material. The origins of fringes modulated on the top of broadband amplitude spectrum, which is measured by electric-optic detector based on thin nonlinear crystal and extracted by fast Fourier transformation, have been analyzed and the major solutions to get rid of these fringes are discussed.

  7. Adoption of Broadband Services

    DEFF Research Database (Denmark)

    Falch, Morten

    2008-01-01

    Broadband is seen as a key infrastructure for developing the information society. For this reason many Governments are actively engaged in stimulating investments in broadband infrastructures and use of broadband services. This chapter compares a wide range of broadband strategies in the most suc....... Many countries have provided active support for stimulating diffusion of broadband and national variants of this type of policies in different countries are important for an explanation of national differences in adoption of broadband....

  8. Application of an Aligned and Unaligned Signal Processing Technique to Investigate Tones and Broadband Noise in Fan and Contra-Rotating Open Rotor Acoustic Spectra

    Science.gov (United States)

    Miles, Jeffrey Hilton; Hultgren, Lennart S.

    2015-01-01

    The study of noise from a two-shaft contra-rotating open rotor (CROR) is challenging since the shafts are not phase locked in most cases. Consequently, phase averaging of the acoustic data keyed to a single shaft rotation speed is not meaningful. An unaligned spectrum procedure that was developed to estimate a signal coherence threshold and reveal concealed spectral lines in turbofan engine combustion noise is applied to fan and CROR acoustic data in this paper (also available as NASA/TM-2015-218865). The NASA Advanced Air Vehicles Program, Advanced Air Transport Technology Project, Aircraft Noise Reduction Subproject supported the current work. The fan and open rotor data were obtained under previous efforts supported by the NASA Quiet Aircraft Technology (QAT) Project and the NASA Environmentally Responsible Aviation (ERA) Project of the Integrated Systems Research Program in collaboration with GE Aviation, respectively. The overarching goal of the Advanced Air Transport (AATT) Project is to explore and develop technologies and concepts to revolutionize the energy efficiency and environmental compatibility of fixed wing transport aircrafts. These technological solutions are critical in reducing the impact of aviation on the environment even as this industry and the corresponding global transportation system continue to grow.

  9. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

    Broadband light emitters operation, which covers multiple wavelengths of the electromagnetic spectrum, has been established as an indispensable element to the human kind, continuously advancing the living standard by serving as sources in important multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which are bulky, and energy hungry. \\tRecent demonstration of ultra-broadband emission from semiconductor light sources in the form of superluminescent light emitting diodes (SLDs) has paved way in realization of broadband emitters on a completely novel platform, which offered compactness, cost effectiveness, and comparatively energy efficient, and are already serving as a key component in medical imaging systems. The low power-bandwidth product is inherent in SLDs operating in the amplified spontaneous emission regime. A quantum leap in the advancement of broadband emitters, in which high power and large bandwidth (in tens of nm) are in demand. Recently, the birth of a new class of broadband semiconductor laser diode (LDs) producing multiple wavelength light in stimulated emission regime was demonstrated. This very recent manifestation of a high power-bandwidth-product semiconductor broadband LDs relies on interband optical transitions via quantum confined dot/dash nanostructures and exploiting the natural inhomogeneity of the self-assembled growth technology. This concept is highly interesting and extending the broad spectrum of stimulated emission by novel device design forms the central focus of this dissertation. \\tIn this work, a simple rate equation numerical technique for modeling InAs/InP quantum dash laser incorporating the properties of inhomogeneous broadening effect on lasing spectra was developed and discussed, followed by a comprehensive experimental analysis

  10. Tapered Yagi-Uda Nanoantennas for Broadband Unidirectional Emission

    CERN Document Server

    Staude, Isabelle; Decker, Manuel; Miroshnichenko, Andrey E; Neshev, Dragomir N; Jagadish, Chennupati; Kivshar, Yuri S

    2012-01-01

    We demonstrate experimentally the operation of tapered Yagi-Uda nanoantennas for broadband unidirectional emission enhancement. The measured transmittance spectra show that, in comparison to untapered reference structures, the tapered nanoantennas exhibit distinct wide-band spectral resonances. The performed full-vectorial numerical calculations are in good qualitative agreement with the measured spectra, further revealing how the near-field profiles of the tapered nanoantennas are directly reflecting their broadband characteristics.

  11. The ultraviolet continuous and emission-line spectra of the Herbig-Haro objects HH 2 and HH 1

    Science.gov (United States)

    Boehm-Vitense, E.; Cardelli, J. A.; Nemec, J. M.; Boehm, K. H.

    1982-01-01

    Recent studies of the continuous spectrum of Herbig-Haro (HH) objects at optical and near-infrared wavelengths and the observation of continuous radiation in the ultraviolet have shown an unexpectedly steep increase of the flux toward shorter wavelengths. The present investigation provides the results of ultraviolet observations of HH 2. The obtained data are compared with the HH 1 data. It is found that HH 2 has an ultraviolet continuous and emission-line spectrum which is similar to that of HH 1. The UV line spectrum of HH 2H indicates an even somewhat larger ionization than does the HH 1 spectrum. As in HH1, the UV emission-line spectrum shows a much higher degree of ionization than that derived from the optical spectrum. Consequently, the same difficulty arises as in the case of HH 1. The complete UV plus optical spectrum cannot be explained by a single plane-parallel shock-wave model.

  12. Broadband radiometry for photodynamic therapy

    Science.gov (United States)

    Folgosi-Correa, M. S.; Caly, J. P.; Nogueira, G. E. C.

    2010-04-01

    The effective irradiance is a useful measure to compare performances of different broadband light sources and to more precisely predict the outcome of a topical photodynamic therapy. The effective irradiance (or effective fluence rate) and the exposition time of the optical radiation usually determine the light dose. The effective irradiance (Eeff) takes into account the spectral irradiance of the source as well as the action spectrum, where the wavelength dependence of both optical diffusion through tissue and photosensitizer are considered. In practice there are no standard action spectra for the currently used photosensitizers. As a consequence, measured values of effective irradiance using different action spectra can not be compared. In order to solve this problem, the basis of the calibration theory developed for the broadband ultraviolet radiometry can be applied, where an experimental radiometer is compared with a standard radiometer. Here is presented a simple set of linear relations in the form Eeff = k . E, where E is the source irradiance and k a real positive value, here denoted as a characteristic of the radiometer, as valuable tools for correction of effective irradiances measured according to different action spectra. As a result, for two effective radiometers with different characteristics k1 and k2, measured values are Eeff and Qeff respectively, and it is easily shown that the value Eeff = Qeff • k1/k2 .

  13. Statistically Based Approach to Broadband Liner Design and Assessment

    Science.gov (United States)

    Nark, Douglas M. (Inventor); Jones, Michael G. (Inventor)

    2016-01-01

    A broadband liner design optimization includes utilizing in-duct attenuation predictions with a statistical fan source model to obtain optimum impedance spectra over a number of flow conditions for one or more liner locations in a bypass duct. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners having impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increasing weighting to specific frequencies and/or operating conditions. One or more broadband design approaches are utilized to produce a broadband liner that targets a full range of frequencies and operating conditions.

  14. A correlated study between effective total macroscopic cross sections and effective energies for neutron beams with continuous spectra

    CERN Document Server

    Kobayashi, H

    1999-01-01

    Two practically useful quantities have been introduced to characterize a continuous-energy-spectrum neutron beam and to describe transmission phenomena of the beam in the field of quantitative neutron radiography. These quantities are the effective energy instead of a peak energy or a mean energy of the spectrum and an effective total macroscopic (ETM) cross section instead of a total macroscopic (TM) cross section as defined for a monochromatic energy. Four neutron beams have been used to measure ETM cross sections at effective energies of 29.8, 17.2, 9.8 meV, and at the In resonance energy of 1.46 eV. Results are studied as a function of estimated effective energy, where the effective energy was estimated by a beam quality indicator (BQI) which has been proposed recently. Validity of ETM cross sections as a function of the effective energy is discussed and correlated with recent nuclear data.

  15. Real-Time Continuous Response Spectra Exceedance Calculation Displayed in a Web-Browser Enables Rapid and Robust Damage Evaluation by First Responders

    Science.gov (United States)

    Franke, M.; Skolnik, D. A.; Harvey, D.; Lindquist, K.

    2014-12-01

    A novel and robust approach is presented that provides near real-time earthquake alarms for critical structures at distributed locations and large facilities using real-time estimation of response spectra obtained from near free-field motions. Influential studies dating back to the 1980s identified spectral response acceleration as a key ground motion characteristic that correlates well with observed damage in structures. Thus, monitoring and reporting on exceedance of spectra-based thresholds are useful tools for assessing the potential for damage to facilities or multi-structure campuses based on input ground motions only. With as little as one strong-motion station per site, this scalable approach can provide rapid alarms on the damage status of remote towns, critical infrastructure (e.g., hospitals, schools) and points of interests (e.g., bridges) for a very large number of locations enabling better rapid decision making during critical and difficult immediate post-earthquake response actions. Details on the novel approach are presented along with an example implementation for a large energy company. Real-time calculation of PSA exceedance and alarm dissemination are enabled with Bighorn, an extension module based on the Antelope software package that combines real-time spectral monitoring and alarm capabilities with a robust built-in web display server. Antelope is an environmental data collection software package from Boulder Real Time Technologies (BRTT) typically used for very large seismic networks and real-time seismic data analyses. The primary processing engine produces continuous time-dependent response spectra for incoming acceleration streams. It utilizes expanded floating-point data representations within object ring-buffer packets and waveform files in a relational database. This leads to a very fast method for computing response spectra for a large number of channels. A Python script evaluates these response spectra for exceedance of one or more

  16. Broadband Liner Optimization for the Source Diagnostic Test Fan

    Science.gov (United States)

    Nark, Douglas M.; Jones, Michael G.

    2012-01-01

    The broadband component of fan noise has grown in relevance with the utilization of increased bypass ratio and advanced fan designs. Thus, while the attenuation of fan tones remains paramount, the ability to simultaneously reduce broadband fan noise levels has become more appealing. This paper describes a broadband acoustic liner optimization study for the scale model Source Diagnostic Test fan. Specifically, in-duct attenuation predictions with a statistical fan source model are used to obtain optimum impedance spectra over a number of flow conditions for three liner locations in the bypass duct. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners aimed at producing impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increased weighting to specific frequencies and/or operating conditions. Typical tonal liner designs targeting single frequencies at one operating condition are first produced to provide baseline performance information. These are followed by multiple broadband design approaches culminating in a broadband liner targeting the full range of frequencies and operating conditions. The broadband liner is found to satisfy the optimum impedance objectives much better than the tonal liner designs. In addition, the broadband liner is found to provide better attenuation than the tonal designs over the full range of frequencies and operating conditions considered. Thus, the current study successfully establishes a process for the initial design and evaluation of novel broadband liner concepts for complex engine configurations.

  17. Broadband Telecommunications Benchmarking Study

    OpenAIRE

    2004-01-01

    This report assesses Ireland's competitiveness relative to 21 countries, with particular focus on the broadband telecommunications requirements of the enterprise sector. The report outlines strengths and weaknesses that currently exist and progress that has already been made. It also makes a series of recommendations to further promote the development of the broadband market in Ireland.

  18. The Broadband Buzz.

    Science.gov (United States)

    Buchanan, Bruce

    2003-01-01

    "Broadband," the term for a variety of high-speed Internet options, opens up many opportunities for online classroom learning. Challenges for school districts include keeping the network running, training teachers, and paying for it. A sidebar lists broadband resources. (MLF)

  19. Incoherent broadband optical pulse generation using an optical gate

    Institute of Scientific and Technical Information of China (English)

    Biao Chen; Qiong Jiang

    2008-01-01

    In two-dimensional (2D) time-spreading/wavelength-hopping optical code division multiple access (OCDMA) systems, employing less coherent broadband optical pulse sources allows lower electrical operating rate and better system performance. An optical gate based scheme for generating weakly coherent(approximately incoherent) broadband optical pulses was proposed and experimentally demonstrated. Inthis scheme, the terahertz optical asymmetric demultiplexer, together with a coherent narrowband controlpulse source, turns an incoherent broadband continuous-wave (CW) light source into the required pulse source.

  20. Simultaneous spectrophotometric determination of overlapping spectra of paracetamol and caffeine in laboratory prepared mixtures and pharmaceutical preparations using continuous wavelet and derivative transform

    Directory of Open Access Journals (Sweden)

    Ahmed Ashour

    2015-03-01

    Full Text Available In the present paper, two spectrophotometric methods were used for the simultaneous analysis of paracetamol (PCT and caffeine (CAF in their laboratory prepared mixtures and pharmaceutical preparations. Simple spectrophotometric analysis of PCT and CAF is not possible due to their complete spectral overlap. The proposed methods are based on the application of continuous wavelet transform (CWT and derivative transform (using Savitsky–Golay filters on the ratio spectra to predict each of CAF and PCT. Several wavelet families were tested. Coif1 and Sym2 were found to give best results under optimum conditions. The transformed signals of ratio spectra were used to plot the calibration curves for both components. The predictability of the built calibrations was validated through their application on several synthetic mixtures of both drugs. The proposed methods were used for the prediction of CAF and PCT in pharmaceutical preparation. The obtained results were statistically compared to a reference HPLC method. No significant differences were found between the obtained results and those from the reference method. Being simple, rapid, cheap and sensitive, the proposed methods are recommended for the routine daily analysis of these two drugs in their mixtures in quality control laboratories.

  1. Broadband adoption by SMES

    OpenAIRE

    Oni, Oluwasola

    2007-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. Because the benefits of broadband for businesses have been widely publicized, the UK government has tried to ensure that there is a wide and fast take-up of the technology. Initial figures showed that broadband adoption by SMEs was particularly slow and there has been little research on the use of broadband by businesses, particularly SMEs. An in-depth study into the roles and activities of t...

  2. Broadband Rotational Spectroscopy

    Science.gov (United States)

    Pate, Brooks

    2014-06-01

    The past decade has seen several major technology advances in electronics operating at microwave frequencies making it possible to develop a new generation of spectrometers for molecular rotational spectroscopy. High-speed digital electronics, both arbitrary waveform generators and digitizers, continue on a Moore's Law-like development cycle that started around 1993 with device bandwidth doubling about every 36 months. These enabling technologies were the key to designing chirped-pulse Fourier transform microwave (CP-FTMW) spectrometers which offer significant sensitivity enhancements for broadband spectrum acquisition in molecular rotational spectroscopy. A special feature of the chirped-pulse spectrometer design is that it is easily implemented at low frequency (below 8 GHz) where Balle-Flygare type spectrometers with Fabry-Perot cavity designs become technologically challenging due to the mirror size requirements. The capabilities of CP-FTMW spectrometers for studies of molecular structure will be illustrated by the collaborative research effort we have been a part of to determine the structures of water clusters - a project which has identified clusters up to the pentadecamer. A second technology trend that impacts molecular rotational spectroscopy is the development of high power, solid state sources in the mm-wave/THz regions. Results from the field of mm-wave chirped-pulse Fourier transform spectroscopy will be described with an emphasis on new problems in chemical dynamics and analytical chemistry that these methods can tackle. The third (and potentially most important) technological trend is the reduction of microwave components to chip level using monolithic microwave integrated circuits (MMIC) - a technology driven by an enormous mass market in communications. Some recent advances in rotational spectrometer designs that incorporate low-cost components will be highlighted. The challenge to the high-resolution spectroscopy community - as posed by Frank De

  3. A Thin Film Broadband Absorber Based on Multi-sized Nanoantennas

    CERN Document Server

    Cui, Yanxia; Fung, Kin Hung; Jin, Yi; Kumar, Anil; He, Sailing; Fang, Nicholas X

    2011-01-01

    We experimentally demonstrate an infrared broadband absorber for TM polarized light based on an array of nanostrip antennas of several different sizes. The broadband property is due to the collective effect of magnetic responses excited by these nano-antennas at distinct wavelengths. By manipulating the differences of the nanostrip widths, the measured spectra clearly validate our design for the purpose of broadening the absorption band. The present broadband absorber works very well in a wide angular range.

  4. Passive broadband acoustic thermometry

    Science.gov (United States)

    Anosov, A. A.; Belyaev, R. V.; Klin'shov, V. V.; Mansfel'd, A. D.; Subochev, P. V.

    2016-04-01

    The 1D internal (core) temperature profiles for the model object (plasticine) and the human hand are reconstructed using the passive acoustothermometric broadband probing data. Thermal acoustic radiation is detected by a broadband (0.8-3.5 MHz) acoustic radiometer. The temperature distribution is reconstructed using a priori information corresponding to the experimental conditions. The temperature distribution for the heated model object is assumed to be monotonic. For the hand, we assume that the temperature distribution satisfies the heat-conduction equation taking into account the blood flow. The average error of reconstruction determined for plasticine from the results of independent temperature measurements is 0.6 K for a measuring time of 25 s. The reconstructed value of the core temperature of the hand (36°C) generally corresponds to physiological data. The obtained results make it possible to use passive broadband acoustic probing for measuring the core temperatures in medical procedures associated with heating of human organism tissues.

  5. Direct UV-written broadband directional broadband planar waveguide couplers

    DEFF Research Database (Denmark)

    Olivero, Massimo; Svalgaard, Mikael

    2005-01-01

    We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation.......We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation....

  6. A new method for an improved determination of continuous photon fluence spectra for X-ray tube voltages up to 150 kV

    International Nuclear Information System (INIS)

    The experimental determination of Bremsstrahlung spectra used in radiation protection dosimetry as well as in medical physics is generally composed of the following steps: acquisition of pulse-height spectra, determination of the detector's inherent response function and unfolding of the measured pulse-height spectra with this function. On the whole, this procedure leads to photon fluence spectra of good quality. It is, however, generally not completely free of artefacts. These occur at both the low- and high-energy sides of the spectrum, with a predominance at the low-energy side. In this work, a new method to overcome this problem is presented. It consists of reconstructing the distorted part of a spectrum on the basis of the total filtration pertinent to the radiation quality considered. The formalism is derived and the ability of the method to provide spectra free of artefacts is demonstrated. (authors)

  7. Broadband Midwave Infrared InAs/GaSb Superlattice Light-Emitting Diodes

    Science.gov (United States)

    Ricker, Russell; Provence, Sydney; Norton, Dennis; Prineas, John; Boggess, Thomas

    Broadband (3.0 μm to 5.0 μm) emission is reported from InAs/GaSb superlattice light-emitting diodes grown via molecular beam epitaxy . Stacked active regions, each with a different emission wavelength, were connected with tunnel junctions, resulting in multiple emission wavelengths in a monolithic structure. Eight active regions provided eight overlapping emission spectra, simulating a broadband spectrum. Chips with mesas of sizes ranging from 24 μm x 24 μm to 400 μm x 400 μm were fabricated and wire bonded to a leadless chip carrier (LCC). The LCC was mounted in a liquid nitrogen cryostat. At low input currents, distinct peaks were observed at 3.3 μm, 3.6 μm, 3.9 μm, 4.2 μm, 4.5 μm, 4.9 μm, and 5.3 μm. At high input currents a continuous spectrum was observed with a peak near 3.8 μm and with a full-width at half-maximum of 1.42 μm. In quasi-continuous operation at 77 K, radiances exceeding 0.35 W/cm2-sr in a Lambertian profile were achieved. Current dependent electroluminescent spectra measured at liquid nitrogen temperatures demonstrate the blending of the various colors from each stage into one smooth spectrum at high currents.

  8. Broadband Phase Spectroscopy over Turbulent Air Paths.

    Science.gov (United States)

    Giorgetta, Fabrizio R; Rieker, Gregory B; Baumann, Esther; Swann, William C; Sinclair, Laura C; Kofler, Jon; Coddington, Ian; Newbury, Nathan R

    2015-09-01

    Broadband atmospheric phase spectra are acquired with a phase-sensitive dual-frequency-comb spectrometer by implementing adaptive compensation for the strong decoherence from atmospheric turbulence. The compensation is possible due to the pistonlike behavior of turbulence across a single spatial-mode path combined with the intrinsic frequency stability and high sampling speed associated with dual-comb spectroscopy. The atmospheric phase spectrum is measured across 2 km of air at each of the 70,000 comb teeth spanning 233  cm(-1) across hundreds of near-infrared rovibrational resonances of CO(2), CH(4), and H(2)O with submilliradian uncertainty, corresponding to a 10(-13) refractive index sensitivity. Trace gas concentrations extracted directly from the phase spectrum reach 0.7 ppm uncertainty, demonstrated here for CO(2). While conventional broadband spectroscopy only measures intensity absorption, this approach enables measurement of the full complex susceptibility even in practical open path sensing.

  9. Tapered Yagi-Uda Nanoantennas for Broadband Unidirectional Emission

    OpenAIRE

    Staude, Isabelle; Ivan S. Maksymov; Decker, Manuel; Miroshnichenko, Andrey E.; Neshev, Dragomir N.; Jagadish, Chennupati; Kivshar, Yuri S.

    2012-01-01

    We demonstrate experimentally the operation of tapered Yagi-Uda nanoantennas for broadband unidirectional emission enhancement. The measured transmittance spectra show that, in comparison to untapered reference structures, the tapered nanoantennas exhibit distinct wide-band spectral resonances. The performed full-vectorial numerical calculations are in good qualitative agreement with the measured spectra, further revealing how the near-field profiles of the tapered nanoantennas are directly r...

  10. Strategies for Complex Mixture Analysis in Broadband Microwave Spectroscopy.

    Science.gov (United States)

    Steber, Amanda L.; Neill, Justin L.; Muckle, Matthew T.; Pate, Brooks H.; Plusquellic, D. F.; Lattanzi, V.; Spezzano, S.; McCarthy, M. C.

    2010-06-01

    Broadband microwave spectra often contain overlapping spectra from a large number of species in the sample mixture, whether in the study of conformational isomers, molecular complexes, reaction products from reactive molecular sources (e.g., electrical discharge), or analysis of chemical mixtures. In these experiments, the identification of individual spectra in the full spectrum through pattern recognition becomes difficult when there is a high density of transitions. Strategies for extracting individual spectra from broadband measurements are discussed. Two approaches for microwave-microwave double resonance spectroscopy have been evaluated. One uses a transition-by-transition screening in a narrowband cavity spectrometer to identify an unknown spectrum and has a time advantage from the increased sensitivity of cavity spectroscopy. The second double-resonance approach uses a broadband spectral editing approach that gives a multiplex advantage in the detection. Both of these experimental techniques are combined with computer-aided assignment algorithms to make the spectral assignment in a minimum of double-resonance observations. The performance of spectral analysis solely using computer-aided assignment is also evaluated. The potential for fully automated spectral decomposition of the broadband spectrum of a complex mixture will be described.

  11. Taxonomic Classification of Asteroids via Broadband Near-Infrared Photometry

    NARCIS (Netherlands)

    Petersen, Eric; Thomas, C.; Trilling, D.; Emery, J.; Delbo, M.; Mueller, M.; Dave, R.

    2010-01-01

    For faint asteroids, it is not practical to obtain near-infrared spectra. However, it may be possible to use broadband photometry to infer spectral classifications and study composition. As a test of this, we processed SpeX near-infrared asteroid spectral data to simulate colors that would be obtain

  12. Metasurface Broadband Solar Absorber

    OpenAIRE

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Milan Sykora; Nina R. Weisse-Bernstein; Luk, Ting S.; Antoinette J. Taylor; Dalvit, Diego A. R.; Hou-Tong Chen

    2016-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experiment...

  13. Broadband Radio Service (BRS) and Educational Broadband Service (EBS) Transmitters

    Data.gov (United States)

    Department of Homeland Security — The Broadband Radio Service (BRS), formerly known as the Multipoint Distribution Service (MDS)/Multichannel Multipoint Distribution Service (MMDS), is a commercial...

  14. Broadband frequency conversion

    DEFF Research Database (Denmark)

    Sanders, Nicolai; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter;

    We present a simple, passive and static setup for broadband frequency conversion. By using simple optical components like lenses, mirrors and gratings, we obtain the spectral angular dispersion to match the second harmonic generation phasematching angles in a nonlinear BiBO crystal. We are able to...... frequency double a single-frequency diode laser, tunable in the 1020-1090 nm range, with almost equal efficiency for all wavelengths. In the experimental setup, the width of the phasematch was increased with a factor of 50. The method can easily be extended to other wavelength ranges and nonlinear crystals...

  15. Dynamic Radio Spectra from two Fireballs

    OpenAIRE

    Obenberger, K. S.; Taylor, G. B.; Lin, C. S.; J. Dowell; Schinzel, F. K.; Stovall, K.

    2015-01-01

    We present dynamic spectra from the LWA1 telescope of two large meteors (fireballs) observed to emit between 37 and 54 MHz. These spectra show the first ever recorded broadband measurements of this newly discovered VHF emission. The spectra show that the emission is smooth and steep, getting very bright at lower frequencies. We suggest that this signal is possibly emission of Langmuir waves and that these waves could be excited by a weak electron beam within the trail. The spectra of one fire...

  16. Dynamic Radio Spectra from two Fireballs

    CERN Document Server

    Obenberger, K S; Lin, C S; Dowell, J; Schinzel, F K; Stovall, K

    2015-01-01

    We present dynamic spectra from the LWA1 telescope of two large meteors (fireballs) observed to emit between 37 and 54 MHz. These spectra show the first ever recorded broadband measurements of this newly discovered VHF emission. The spectra show that the emission is smooth and steep, getting very bright at lower frequencies. We suggest that this signal is possibly emission of Langmuir waves and that these waves could be excited by a weak electron beam within the trail. The spectra of one fireball displays broadband temporal frequency sweeps. We suggest that these sweeps are evidence of individual expanding clumps of emitting plasma. While some of these proposed clumps may have formed at the very beginning of the fireball event, others must have formed seconds after the initial event.

  17. Dynamic radio spectra from two fireballs

    Science.gov (United States)

    Obenberger, K. S.; Taylor, G. B.; Lin, C. S.; Dowell, J.; Schinzel, F. K.; Stovall, K.

    2015-11-01

    We present dynamic spectra from the Long Wavelength Array telescope of two large meteors (fireballs) observed to emit between 37 and 54 MHz. These spectra show the first ever recorded broadband measurements of this newly discovered VHF emission. The spectra show that the emission is smooth and steep, getting very bright at lower frequencies. We suggest that this signal is possibly emission of Langmuir waves and that these waves could be excited by a bump-on-tail instability within the trail. The spectra of one fireball display broadband temporal frequency sweeps. We suggest that these sweeps are evidence of individual expanding clumps of emitting plasma. While some of these proposed clumps may have formed at the very beginning of the fireball event, others must have formed seconds after the initial event.

  18. Ultra-Broadband Coherent Supercontinuum Frequency Comb

    CERN Document Server

    Ruehl, Axel; Cossel, Kevin C; Chen, Lisheng; McKay, Hugh; Thomas, Brian; Benko, Craig; Dong, Liang; Dudley, John M; Fermann, Martin E; Hartl, Ingmar; Ye, Jun

    2011-01-01

    We present detailed studies of the coherence properties of an ultra-broadband super-continuum, enabled by a new approach involving continuous wave laser sources to independently probe both the amplitude and phase noise quadratures across the entire spectrum. The continuum coherently spans more than 1.5 octaves, supporting Hz-level comparison of ultrastable lasers at 698 nm and 1.54 {\\mu}m. We present the first numerical simulation of the accumulated comb coherence in the limit of many pulses, in contrast to the single-pulse level, with systematic experimental verification. The experiment and numerical simulations reveal the presence of quantum-seeded broadband amplitude noise without phase coherence degradation, including the discovery of a dependence of the super-continuum coherence on the fiber fractional Raman gain.

  19. Broadband pendulum energy harvester

    Science.gov (United States)

    Liang, Changwei; Wu, You; Zuo, Lei

    2016-09-01

    A novel electromagnetic pendulum energy harvester with mechanical motion rectifier (MMR) is proposed and investigated in this paper. MMR is a mechanism which rectifies the bidirectional swing motion of the pendulum into unidirectional rotation of the generator by using two one-way clutches in the gear system. In this paper, two prototypes of pendulum energy harvester with MMR and without MMR are designed and fabricated. The dynamic model of the proposed MMR pendulum energy harvester is established by considering the engagement and disengagement of the one way clutches. The simulation results show that the proposed MMR pendulum energy harvester has a larger output power at high frequencies comparing with non-MMR pendulum energy harvester which benefits from the disengagement of one-way clutch during pendulum vibration. Moreover, the proposed MMR pendulum energy harvester is broadband compare with non-MMR pendulum energy harvester, especially when the equivalent inertia is large. An experiment is also conducted to compare the energy harvesting performance of these two prototypes. A flywheel is attached at the end of the generator to make the disengagement more significant. The experiment results also verify that MMR pendulum energy harvester is broadband and has a larger output power at high frequency over the non-MMR pendulum energy harvester.

  20. Broadband terahertz fiber directional coupler

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Jepsen, Peter Uhd;

    2010-01-01

    We present the design of a short broadband fiber directional coupler for terahertz (THz) radiation and demonstrate a 3 dB coupler with a bandwidth of 0:6 THz centered at 1:4 THz. The broadband coupling is achieved by mechanically downdoping the cores of a dual-core photonic crystal fiber...

  1. Broadband Fiber Raman Power-Amplifier for Narrow Linewidth Tunable Seed Lasers Used in Spectroscopic Sensing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an energy and space efficient high power continuous wave (cw) narrow linewidth broadband fiber Raman amplifier (FRA) with spectrally tunable...

  2. AIRTV: Broadband Direct to Aircraft

    Science.gov (United States)

    Sorbello, R.; Stone, R.; Bennett, S. B.; Bertenyi, E.

    2002-01-01

    Airlines have been continuously upgrading their wide-body, long-haul aircraft with IFE (in-flight entertainment) systems that can support from 12 to 24 channels of video entertainment as well as provide the infrastructure to enable in-seat delivery of email and internet services. This is a direct consequence of increased passenger demands for improved in-flight services along with the expectations that broadband delivery systems capable of providing live entertainment (news, sports, financial information, etc.) and high speed data delivery will soon be available. The recent events of Sept. 11 have slowed the airline's upgrade of their IFE systems, but have also highlighted the compelling need for broadband aeronautical delivery systems to include operational and safety information. Despite the impact of these events, it is estimated that by 2005 more than 3000 long haul aircraft (servicing approximately 1 billion passengers annually) will be fully equipped with modern IFE systems. Current aircraft data delivery systems, which use either Inmarsat or NATS, are lacking in bandwidth and consequently are unsuitable to satisfy passenger demands for broadband email/internet services or the airlines' burgeoning data requirements. Present live video delivery services are limited to regional coverage and are not readily expandable to global or multiregional service. Faced with a compelling market demand for high data transport to aircraft, AirTV has been developing a broadband delivery system that will meet both passengers' and airlines' needs. AirTV is a global content delivery system designed to provide a range of video programming and data services to commercial airlines. When AirTV is operational in 2004, it will provide a broadband connection directly to the aircraft, delivering live video entertainment, internet/email service and essential operational and safety data. The system has been designed to provide seamless global service to all airline routes except for those

  3. AIRTV: Broadband Direct to Aircraft

    Science.gov (United States)

    Sorbello, R.; Stone, R.; Bennett, S. B.; Bertenyi, E.

    2002-01-01

    Airlines have been continuously upgrading their wide-body, long-haul aircraft with IFE (in-flight entertainment) systems that can support from 12 to 24 channels of video entertainment as well as provide the infrastructure to enable in-seat delivery of email and internet services. This is a direct consequence of increased passenger demands for improved in-flight services along with the expectations that broadband delivery systems capable of providing live entertainment (news, sports, financial information, etc.) and high speed data delivery will soon be available. The recent events of Sept. 11 have slowed the airline's upgrade of their IFE systems, but have also highlighted the compelling need for broadband aeronautical delivery systems to include operational and safety information. Despite the impact of these events, it is estimated that by 2005 more than 3000 long haul aircraft (servicing approximately 1 billion passengers annually) will be fully equipped with modern IFE systems. Current aircraft data delivery systems, which use either Inmarsat or NATS, are lacking in bandwidth and consequently are unsuitable to satisfy passenger demands for broadband email/internet services or the airlines' burgeoning data requirements. Present live video delivery services are limited to regional coverage and are not readily expandable to global or multiregional service. Faced with a compelling market demand for high data transport to aircraft, AirTV has been developing a broadband delivery system that will meet both passengers' and airlines' needs. AirTV is a global content delivery system designed to provide a range of video programming and data services to commercial airlines. When AirTV is operational in 2004, it will provide a broadband connection directly to the aircraft, delivering live video entertainment, internet/email service and essential operational and safety data. The system has been designed to provide seamless global service to all airline routes except for those

  4. Polarized spectra calculation and continuous wave laser operation of Yb-doped disordered Ca3La2(BO3)4 crystal

    Science.gov (United States)

    Wang, Yeqing; Chen, Aixi; You, Zhenyu; Tu, Chaoyang

    2015-12-01

    A notable disorder crystal Yb:Ca3La2(BO3)4 crystal with Yb3+ ion doping concentration of 10 at.% was grown by the Czochralski method. The polarized absorption, polarized emission, and polarized gain cross sections were systematically calculated. The laser operations were investigated with Yb:Ca3La2(BO3)4 crystals cut along the a, b, and c crystallographic axes. The highest output power of 3.88 W was obtained by using the b-cut Yb:Ca3La2(BO3)4 crystal, with a slope efficiency of 62%. Additionally, it was confirmed that the output laser spectra were largely dependent on the output coupler.

  5. Metasurface Broadband Solar Absorber

    CERN Document Server

    Azad, A K; Sykora, M; Weisse-Bernstein, N R; Luk, T S; Taylor, A J; Dalvit, D A R; Chen, H -T

    2015-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. Furthermore, we discuss the potential use of our metasurface absorber design in solar thermophotovoltaics by exploiting refractory plasmonic materials.

  6. Metasurface Broadband Solar Absorber

    Science.gov (United States)

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  7. Metamaterial Broadband Angular Selectivity

    CERN Document Server

    Shen, Yichen; Wang, Zhiyu; Wang, Li; Celanovic, Ivan; Ran, Lixin; Joannopoulos, John D; Soljacic, Marin

    2014-01-01

    We demonstrate how broadband angular selectivity can be achieved with stacks of one-dimensionally periodic photonic crystals, each consisting of alternating isotropic layers and effective anisotropic layers, where each effective anisotropic layer is constructed from a multilayered metamaterial. We show that by simply changing the structure of the metamaterials, the selective angle can be tuned to a broad range of angles; and, by increasing the number of stacks, the angular transmission window can be made as narrow as desired. As a proof of principle, we realize the idea experimentally in the microwave regime. The angular selectivity and tunability we report here can have various applications such as in directional control of electromagnetic emitters and detectors.

  8. Metasurface Broadband Solar Absorber.

    Science.gov (United States)

    Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  9. The Broadband Spectral Variability of Holmberg IX X-1

    CERN Document Server

    Walton, D J; Harrison, F A; Middleton, M J; Fabian, A C; Bachetti, M; Barret, D; Miller, J M; Ptak, A; Rana, V; Stern, D; Tao, L

    2016-01-01

    We present the results from four new broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 ($L_{\\rm{X}} > 10^{40}$ erg s$^{-1}$), performed by the $Suzaku$ and $NuSTAR$ observatories in coordination. Combined with the two prior observations coordinating $XMM$-$Newton$, $Suzaku$ and $NuSTAR$, we now have broadband observations of this remarkable source from six separate epochs. Two of these new observations probe lower fluxes than seen previously, allowing us to extend our knowledge of the broadband spectral variability exhibited by Holmberg IX X-1. The broadband spectra are well fit by two thermal blackbody components, which dominate the emission below 10 keV, as well as a steep ($\\Gamma \\sim 3.5$) powerlaw tail which dominates above $\\sim$15 keV. Remarkably, while the 0.3-10.0 keV flux varies by a factor of $\\sim$3 between all these epochs, the 15-40 keV flux varies by only $\\sim$20%. Although the spectral variability is strongest in the $\\sim$1-10 keV band, the broadband var...

  10. Combless broadband terahertz generation with conventional laser diodes.

    Science.gov (United States)

    Molter, D; Wagner, A; Weber, S; Jonuscheit, J; Beigang, R

    2011-03-14

    We present a novel technique to generate a continuous, combless broadband Terahertz spectrum with conventional low-cost laser diodes. A standard time-domain spectroscopy system using photoconductive antennas is pumped by the output of two tunable diode lasers. Using fine tuning for one laser and fine and coarse tuning for the second laser, difference frequency generation results in a continuous broadband THz spectrum. Fast coarse-tuning is achieved by a simple spatial light modulator introduced in an external cavity. The results are compared to multi-mode operation for THz generation.

  11. Recipe for continuous monitoring of total ozone with a precision of around 1 DU applying mid-infrared solar absorption spectra

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2007-06-01

    Full Text Available Mid-infrared solar absorption spectra recorded by a state-of-the-art ground-based FTIR system have the potential to provide precise total O3 amounts. The currently best-performing retrieval approaches use a combination of small and broad spectral O3 windows between 780 and 1015 cm−1. We show that for these approaches uncertainties in the temperature profile are by far the major error sources. We demonstrate that a joint optimal estimation of temperature and O3 profiles widely eliminates this error. The improvements are documented by an extensive theoretical error estimation. Our results suggest that mid-infrared FTIR measurements can provide total O3 amounts with a precision of around 1 DU, placing this method among the most precise ground-based O3 monitoring techniques. We recapitulate the requirements on instrumental hardware and retrieval necessary to achieve this high precision.

  12. 47 CFR 90.18 - Public Safety 700 MHz Nationwide Broadband Network.

    Science.gov (United States)

    2010-10-01

    ... Network. 90.18 Section 90.18 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... 700 MHz Nationwide Broadband Network. The 763-768/793-798 MHz band is dedicated to a broadband public..., pursuant to a Network Sharing Agreement and such other agreements as the Commission may require....

  13. Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) – applicability and corrections

    OpenAIRE

    U. Platt; J. Meinen; D. Pöhler; T. Leisner

    2008-01-01

    Atmospheric trace gas measurements by cavity assisted long-path absorption spectroscopy are an emerging technology. An interesting approach is the combination of CEAS with broadband light sources, the broadband CEAS (BB-CEAS). BB-CEAS lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light pa...

  14. Global characterization of seismic noise with broadband seismometers

    OpenAIRE

    Coughlin, Michael William; Harms, Jan

    2012-01-01

    In this paper, we present an analysis of seismic spectra that were calculated from all broadband channels (BH?) made available through IRIS, NIED F-net and Orfeus servers covering the past five years and beyond. A general characterization of the data is given in terms of spectral histograms and data-availability plots. We show that the spectral information can easily be categorized in time and regions. Spectral histograms indicate that seismic stations exist in Africa, Australia and Antarctic...

  15. Broadband Advanced Spectral System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NovaSol proposes to develop an advanced hyperspectral imaging system for earth science missions named BRASS (Broadband Advanced Spectral System). BRASS combines...

  16. Heterogeneous broadband network

    Science.gov (United States)

    Dittmann, Lars

    1995-11-01

    Although the vision for the future Integrated Broadband Communication Network (IBCN) is an all optical network, it is certain that for a long period to come, the network will remain very heterogeneous, with a mixture of different physical media (fiber, coax and twisted pair), transmission systems (PDH, SDH, ADSL) and transport protocols (TCP/IP, AAL/ATM, frame relay). In the current work towards the IBCN, the ATM concept is considered the generic network protocol for both public and private network, with the ability to use different underlying transmission protocols and, through adaptation protocols, provide the appropriate services (old as well as new) to the customer. One of the major difficulties of heterogeneous network is the restriction that is usually given by the lowest common denominator, e.g. in terms of single channel capacity. A possible way to overcome these limitations is by extending the ATM concept with a multilink capability, that allows us to use separate resources as one common. The improved flexibility obtained by this protocol extension further allows a real time optimization of network and call configuration, without any impact on the quality of service seen from the user. This paper describes an example of an ATM based multilink protocol that has been experimentally implemented within the RACE project 'STRATOSPHERIC'. The paper outlines the complexity of introducing an extra network functionality compared with the added value, such as an improved ability to recover an error due to a malfunctioning network component.

  17. Broadband Dielectric Spectroscopy on Human Blood

    CERN Document Server

    Wolf, M; Lunkenheimer, P; Loidl, A

    2011-01-01

    Dielectric spectra of human blood reveal a rich variety of dynamic processes. Achieving a better characterization and understanding of these processes not only is of academic interest but also of high relevance for medical applications as, e.g., the determination of absorption rates of electromagnetic radiation by the human body. The dielectric properties of human blood are studied using broadband dielectric spectroscopy, systematically investigating the dependence on temperature and hematocrit value. By covering a frequency range from 1 Hz to 40 GHz, information on all the typical dispersion regions of biological matter is obtained. We find no evidence for a low-frequency relaxation (alpha-relaxation) caused, e.g., by counterion diffusion effects as reported for some types of biological matter. The analysis of a strong Maxwell-Wagner relaxation arising from the polarization of the cell membranes in the 1-100 MHz region (beta-relaxation) allows for the test of model predictions and the determination of variou...

  18. Modeling the broadband persistent emission of magnetars

    CERN Document Server

    Zane, Silvia; Nobili, Luciano; Rea, Nanda

    2010-01-01

    In this paper, we discuss our first attempts to model the broadband persistent emission of magnetars within a self consistent, physical scenario. We present the predictions of a synthetic model that we calculated with a new Monte Carlo 3-D radiative code. The basic idea is that soft thermal photons (e.g. emitted by the star surface) can experience resonant cyclotron upscattering by a population of relativistic electrons threated in the twisted magnetosphere. Our code is specifically tailored to work in the ultra-magnetized regime; polarization and QED effects are consistently accounted for, as well different configurations for the magnetosphere. We discuss the predicted spectral properties in the 0.1-1000 keV range, the polarization properties, and we present the model application to a sample of magnetars soft X-ray spectra.

  19. Broadband Spectral Study of Magnetar Bursts

    Science.gov (United States)

    Kirmizibayrak, Demet; Gogus, Ersin; Sasmaz Mus, Sinem; Kaneko, Yuki

    2016-07-01

    Magnetar bursts occur sporadically on random occasions, and every burst-active episode carries unique information about the bursting magnetar. Therefore, in-depth spectral and temporal analyses of each of the magnetar bursts provide new insights into the bursting and radiation mechanisms. There have been a number of studies over the last decade, investigating the spectral and temporal properties of magnetar bursts. The spectra of typical magnetar bursts were generally described with the Comptonized model or the sum of two blackbody functions. However, it was recently shown that the actual spectral nature of these bursts can be conclusively determined if the spectral analysis is performed on a wide energy coverage. We present the results of in-depth systematic broadband (2 - 250 keV) spectral analysis of a large number of bursts originated from three magnetars: SGR 1806-20, SGR 1900+14, and SGR J1550-5418, observed with the Rossi X-ray Timing Explorer.

  20. Broadband for Public Libraries: Importance, Issues, and Research Needs

    Science.gov (United States)

    Mandel, Lauren H.; Bishop, Bradley Wade; McClure, Charles R.; Bertot, John Carlo; Jaeger, Paul T.

    2010-01-01

    U.S. public libraries provide free public internet services to the communities that they serve, but require robust, high-speed broadband internet connections to continue meeting public demands. The 2008-2009 "Public Library Funding & Technology Access Study" ("PLFTAS") illustrates challenges that public libraries encounter in achieving broadband…

  1. Driving demand for broadband networks and services

    CERN Document Server

    Katz, Raul L

    2014-01-01

    This book examines the reasons why various groups around the world choose not to adopt broadband services and evaluates strategies to stimulate the demand that will lead to increased broadband use. It introduces readers to the benefits of higher adoption rates while examining the progress that developed and emerging countries have made in stimulating broadband demand. By relying on concepts such as a supply and demand gap, broadband price elasticity, and demand promotion, this book explains differences between the fixed and mobile broadband demand gap, introducing the notions of substitution and complementarity between both platforms. Building on these concepts, ‘Driving Demand for Broadband Networks and Services’ offers a set of best practices and recommendations aimed at promoting broadband demand.  The broadband demand gap is defined as individuals and households that could buy a broadband subscription because they live in areas served by telecommunications carriers but do not do so because of either ...

  2. Action spectra again?

    Science.gov (United States)

    Coohill, T P

    1991-11-01

    of effect. Preliminary estimates suggest that ozone layer depletion may seriously impact such important biological end-points as skin cancer, cataracts, the immune system, crop yields, and oceanic phytoplankton. So action spectra continue to play a central role in important photobiological research. PMID:1798760

  3. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  4. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S.

    1995-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impendance. This paper discusses three aspects of broadband impendance modeling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f cavity. The last is a discussion of requirements for the mathematical form of an impendance which follow from the general properties of impendances.

  5. Broadband cavity enhanced spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    Science.gov (United States)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Rudich, Y.; Brown, S. S.

    2015-09-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity enhanced spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99933 ± 0.00003 (670 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.49 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device (CCD) array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity enhanced spectroscopy and cavity ringdown spectroscopy agree within 2 % (slope for linear fit = 0.98 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity enhanced spectroscopy and calculated based on flow dilution are also well-correlated, with r2 = 0.9998. During constant, mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1-min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically-based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to trace gases, this approach will be appropriate for

  6. Stochastic generation of continuous wave spectra

    DEFF Research Database (Denmark)

    Trulsen, J.; Dysthe, K. B.; Pécseli, Hans

    1983-01-01

    Wave packets of electromagnetic or Langmuir waves trapped in a well between oscillating reflectors are considered. An equation for the temporal evolution of the probability distribution for the carrier wave number is derived, and solved analytically in terms of moments in the limits of long...... and short wavelengths. The relevance of the results for self-generated stochasticity for harmonically oscillating reflectors is pointed out, and the physical implications of the results are discussed....

  7. Omnidirectional and broadband absorption enhancement from trapezoidal Mie resonators in semiconductor metasurfaces

    CERN Document Server

    Pala, Ragip A; Aydin, Koray; Atwater, Harry A

    2015-01-01

    Light trapping in planar ultrathin-film solar cells is limited due to a small number of optical modes available in the thin-film slab. A nanostructured thin-film design could surpass this limit by providing broadband increase in the local density of states in a subwavelength volume and maintaining efficient coupling of light. Here we report a broadband metasurface design, enabling efficient and broadband absorption enhancement by direct coupling of incoming light to resonant modes of subwavelength-scale Mie nanoresonators defined in the thin-film active layer. Absorption was investigated both theoretically and experimentally in prototypes consisting of lithographically patterned, two-dimensional periodic arrays of silicon nanoresonators on silica substrates. A crossed trapezoid resonator shape of rectangular cross section is used to excite broadband Mie resonances across the visible and near-IR spectra. Our numerical simulations, optical absorption measurements and photocurrent spectral response measurements ...

  8. Broadband/Wideband Magnetoelectric Response

    Directory of Open Access Journals (Sweden)

    Chee-Sung Park

    2012-01-01

    Full Text Available A broadband/wideband magnetoelectric (ME composite offers new opportunities for sensing wide ranges of both DC and AC magnetic fields. The broadband/wideband behavior is characterized by flat ME response over a given AC frequency range and DC magnetic bias. The structure proposed in this study operates in the longitudinal-transversal (L-T mode. In this paper, we provide information on (i how to design broadband/wideband ME sensors and (ii how to control the magnitude of ME response over a desired frequency and DC bias regime. A systematic study was conducted to identify the factors affecting the broadband/wideband behavior by developing experimental models and validating them against the predictions made through finite element modeling. A working prototype of the sensor with flat bands for both DC and AC magnetic field conditions was successfully obtained. These results are quite promising for practical applications such as current probe, low-frequency magnetic field sensing, and ME energy harvester.

  9. Broadband Neutron Interferometer

    OpenAIRE

    Pushin, Dmitry A.; Sarenac, Dusan; Hussey, Dan; Miao, Houxun; Arif, Muhammad; Cory, David G.; Huber, Michael G.; Jacobson, David; LaManna, Jacob; Parker, Joseph D.; Shinohara, Taken; Ueno, Wakana; Wen, Han

    2016-01-01

    We demonstrate a two phase-grating, multi-beam neutron interferometer by using a modified Ronchi setup in a far-field regime. The functionality of the interferometer is based on the universal \\moire effect that was recently implemented for X-ray phase-contrast imaging in the far-field regime. Interference fringes were achieved with monochromatic, bichromatic, and polychromatic neutron beams; for both continuous and pulsed beams. This far-field neutron interferometry allows for the utilization...

  10. AIS-2 spectra of California wetland vegetation

    Science.gov (United States)

    Gross, Michael F.; Ustin, Susan L.; Klemas, Vytautas

    1987-01-01

    Spectral data gathered by Airborne Imaging Spectrometers-2 from wetlands were analyzed. Spectra representing stands of green Salicornia virginica, green Sesuvium verrucosum, senescing Distichlis spicata, a mixture of senescing Scirpus acutus and Scirpus californicus, senescing Scirpus paludosus, senescent S. paludosus, mowed senescent S. paludosus, and soil were isolated. No difference among narrowband spectral reflectance of the cover types was apparent between 0.8 to 1.6 micron. There were, however, broadband differences in brightness. These differences were sufficient to permit a fairly accurate decomposition of the image into its major cover type components using a procedure that assumes an additive linear mixture of surface spectra.

  11. Broadband Neutron Interferometer

    CERN Document Server

    Pushin, Dmitry A; Hussey, Dan; Miao, Houxun; Arif, Muhammad; Cory, David G; Huber, Michael G; Jacobson, David; LaManna, Jacob; Parker, Joseph D; Shinohara, Taken; Ueno, Wakana; Wen, Han

    2016-01-01

    We demonstrate a two phase-grating, multi-beam neutron interferometer by using a modified Ronchi setup in a far-field regime. The functionality of the interferometer is based on the universal \\moire effect that was recently implemented for X-ray phase-contrast imaging in the far-field regime. Interference fringes were achieved with monochromatic, bichromatic, and polychromatic neutron beams; for both continuous and pulsed beams. This far-field neutron interferometry allows for the utilization of the full neutron flux for precise measurements of potential gradients, and expands neutron phase-contrast imaging techniques to more intense polycromatic neutron beams.

  12. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    CERN Document Server

    Lin, Lin; Baring, Matthew G; Granot, Jonathan; Kouveliotou, Chryssa; Kaneko, Yuki; van der Horst, Alexander; Gruber, David; von Kienlin, Andreas; Younes, George; Watts, Anna L; Gehrels, Neil

    2012-01-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT Windowed Timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5 - 200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT/GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbo...

  13. An Analysis of Spectra in the Red Rectangle Nebula

    Indian Academy of Sciences (India)

    Frédéric Zagury

    2005-12-01

    This paper presents an analysis of a series of spectra in the Red Rectangle nebula. Only the reddest part of the spectra can safely be attributed to light from the nebula, and indicates Rayleigh scattering by the gas, in conformity with the large angles of scattering involved and the proximity of the star. In the blue, light from HD 44179, refracted or scattered in the atmosphere, dominates the spectra. This paper questions the reliability of ground-based broad-band spectra of extended objects in the blue.

  14. Few-cycle, Broadband, Mid-infrared Optical Parametric Oscillator Pumped by a 20-fs Ti:sapphire Laser

    CERN Document Server

    Kumar, Suddapalli Chaitanya; Ideguchi, Takuro; Yan, Ming; Holzner, Simon; Hänsch, Theodor W; Picqué, Nathalie; Ebrahim-Zadeh, Majid

    2014-01-01

    We report a few-cycle, broadband, singly-resonant optical parametric oscillator (OPO) for the mid-infrared based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN), synchronously pumped by a 20-fs Ti:sapphire laser. By using crystal interaction lengths as short as 250 um, and careful dispersion management of input pump pulses and the OPO resonator, near-transform-limited, few-cycle idler pulses tunable across the mid-infrared have been generated, with as few as 3.7 optical cycles at 2682 nm. The OPO can be continuously tuned over 2179-3732 nm by cavity delay tuning, providing up to 33 mW of output power at 3723 nm. The idler spectra exhibit stable broadband profiles with bandwidths spaning over 422 nm (FWHM) recorded at 3732 nm. We investigate the effect of crystal length on spectral bandwidth and pulse duration at a fixed wavelength, confirming near-transform-limited idler pulses for all grating interaction lengths. By locking the repetition frequency of the pump laser to a radio-frequency reference, and with...

  15. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  16. Broadband SHF Direction-Finder

    Directory of Open Access Journals (Sweden)

    S. Radionov

    2008-06-01

    Full Text Available The original design of the compact broadband direction-finder is presented in this paper. The cylindrical monopole antenna serves as a primary source of the reflector- type antenna. "Zero-amplitude" technique is used for bearing the SHF sources. The model experiments with the proposed direction-finder prototype in the frequency band 6 GHz - 11 GHz have been carried out.

  17. Broadband Loaded Cylindrical Monopole Antenna

    OpenAIRE

    Boucher, Solene; Sharaiha, Ala; Potier, Patrick

    2013-01-01

    Ahstract-A broadband printed monopole antenna based on the variation of the conductivity along its length is proposed .. The result indicates that a non-monotonous repartition provides interesting performances in terms of impedance bandwidth but also concerning antenna gain. The achievement of the method is demonstrated through its application, using the carbon fibers to perform this conductivity variation. Monopole antenna presents a large impedance bandwidth of 123% with an interesting gain...

  18. The social surplus of broadband initiatives in compulsory education

    Directory of Open Access Journals (Sweden)

    David Peter Parsons

    2016-10-01

    Full Text Available In 2010, the New Zealand government embarked upon an ambitious programme of broadband infrastructure investment, a process that will continue until at least 2019. Part of this investment is specifically targeted at compulsory education, with initiatives that include bringing fibre connections to the school gate, supporting on-site network upgrades (including wireless and providing teaching, learning and support services delivered through these networks. Such investments are not made without some projections of the likely rate of return, but calculating return on investment (ROI in educational broadband is complex, as it encompasses a range of factors. This article reports on an interview-based study engaging a range of stakeholders in educational broadband provision. The study utilises a research model that considers the various elements of social surplus, namely; producer surplus (savings, producer surplus (profit and consumer surplus (perceived value over and above cost, to explore the elements of social surplus that have been used to define educational broadband ROI calculations and justify the scale of investment. The results indicate that all three components of social surplus are relevant, though the concept of profit can only be seen in the broader context of long term contributions to the economy. A note of caution is that projections of ROI based only on positive returns fail to acknowledge the potential for some innovations to actually increase costs. Further, purely quantitative models do not properly take into account qualitative components of consumer surplus.

  19. Broadband cavity enhanced spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    OpenAIRE

    Washenfelder, R. A.; A. R. Attwood; Flores, J. M.; Rudich, Y.; S. S. Brown

    2015-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity enhanced spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and ...

  20. Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers

    OpenAIRE

    Varma, R. M.; Ball, S. M.; Brauers, T.; H.-P. Dorn; U. Heitmann; Jones, R L; U. Platt; D. Pöhler; A. A. Ruth; Shillings, A. J. L.; J. Thieser; A. Wahner; D. S. Venables

    2013-01-01

    Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three s...

  1. Broadband detection of squeezed vacuum: A spectrum of quantum states

    OpenAIRE

    Breitenbach, Gerd; Illuminati, Fabrizio; Schiller, Stephan; Mlynek, Jurgen

    1999-01-01

    We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a "spectrum" of density matrices and Wigner functions is obtai...

  2. Freely-tunable broadband polarization rotator for terahertz waves

    Science.gov (United States)

    Peng, Ru-Wen; Fan, Ren-Hao; Zhou, Yu; Jiang, Shang-Chi; Xiong, Xiang; Huang, Xian-Rong; Wang, Mu

    It is known that commercially-available terahertz (THz) emitters usually generate linearly polarized waves only along certain directions, but in practice, a polarization rotator that is capable of rotating the polarization of THz waves to any direction is particularly desirable and it will have various important applications. In this work, we demonstrate a freely tunable polarization rotator for broadband THz waves using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized THz wave to any desired direction with nearly perfect conversion efficiency. The device performance has been experimentally demonstrated by both THz transmission spectra and direct imaging. The polarization rotation originates from multi wave interference in the three-layer grating structure based on the scattering-matrix analysis. We can expect that this active broadband polarization rotator has wide applications in analytical chemistry, biology, communication technology, imaging, etc.. Reference: R. H. Fan, Y. Zhou, X. P. Ren, R. W. Peng, S. C. Jiang, D. H. Xu, X. Xiong, X. R. Huang, and Mu Wang, Advanced Materials 27,1201(2015). Freely-tunable broadband polarization rotator for terahertz waves.

  3. Broadband distortion modeling in Lyman-$\\alpha$ forest BAO fitting

    CERN Document Server

    Blomqvist, Michael; Bautista, Julian E; Ariño, Andreu; Busca, Nicolás G; Miralda-Escudé, Jordi; Slosar, Anže; Font-Ribera, Andreu; Margala, Daniel; Schneider, Donald P; Vazquez, Jose A

    2015-01-01

    In recent years, the Lyman-$\\alpha$ absorption observed in the spectra of high-redshift quasars has been used as a tracer of large-scale structure by means of the three-dimensional Lyman-$\\alpha$ forest auto-correlation function at redshift $z\\simeq 2.3$, but the need to fit the quasar continuum in every absorption spectrum introduces a broadband distortion that is difficult to correct and causes a systematic error for measuring any broadband properties. We describe a $k$-space model for this broadband distortion based on a multiplicative correction to the power spectrum of the transmitted flux fraction that suppresses power on scales corresponding to the typical length of a Lyman-$\\alpha$ forest spectrum. Implementing the distortion model in fits for the baryon acoustic oscillation (BAO) peak position in the Lyman-$\\alpha$ forest auto-correlation, we find that the fitting method recovers the input values of the linear bias parameter $b_{F}$ and the redshift-space distortion parameter $\\beta_{F}$ for mock dat...

  4. Broadband Spectral Analysis of Aql X-1

    CERN Document Server

    Raichur, H; Dewangan, G

    2011-01-01

    We present the results of a broadband spectral study of the transient Low Mass X-ray Binary Aql X-1 observed by Suzaku and Rossi X-ray Timing Explorer satellites. The source was observed during its 2007 outburst in the High/Soft (Banana) state and in the Low/Hard (Extreme Island) state. Both the Banana state and the Extreme Island state spectra are best described by a two component model consisting of a soft multi-colour blackbody emission likely originating from the accretion disk and a harder Comptonized emission from the boundary layer. Evidence for a hard tail (extending to ~50 keV) is found during the Banana state; this further (transient) component, accounting for atleast ~1.5% of the source luminosity, is modeled by a power-law. Aql X-1 is the second Atoll source after GX 13+1 to show a high energy tail. The presence of a weak but broad Fe line provides further support for a standard accretion disk extending nearly to the neutron star surface. The input photons for the Comptonizing boundary layer could...

  5. Analysis of the Proposed Ghana Broadband Strategy

    DEFF Research Database (Denmark)

    Williams, Idongesit; Botwe, Yvonne

    This project studied the Ghana Broadband Strategy with the aim of evaluating the recommendations in the strategy side by side the broadband development in Ghana. The researchers conducted interviews both officially and unofficially with ICT stakeholders, made observations, studied Government...... intervention policies recommended in the Ghana broadband policy is used to evaluate the broadband market to find out whether the strategy consolidates with the Strengths and opportunities of the market and whether it corrects the anomalies that necessitate the weaknesses and threats to the market....... The strategy did address some threats and weaknesses of the broadband market. It also consolidated on some strengths and opportunities of the broadband market. The researchers also discovered that a market can actually grow without a policy. But a market will grow faster if a well implemented policy is guiding...

  6. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

    An authoritative introduction to the roles of switching and transmission in broadband integrated services networks Principles of Broadband Switching and Networking explains the design and analysis of switch architectures suitable for broadband integrated services networks, emphasizing packet-switched interconnection networks with distributed routing algorithms. The text examines the mathematical properties of these networks, rather than specific implementation technologies. Although the pedagogical explanations in this book are in the context of switches, many of the fundamenta

  7. Mapping the broadband polarization properties of linear 2D SOI photonic crystal waveguides

    DEFF Research Database (Denmark)

    Canning, John; Skivesen, Nina; Kristensen, Martin;

    2007-01-01

    Both quasi-TE and TM polarisation spectra for a silicon- on-insulator (SOI) waveguide are recorded over (1100-1700) nm using a broadband supercontinuum source. By studying both the input and output polarisation eigenstates we observe narrowband resonant cross coupling near the lowest quasi-TE mode...... cut-off. We also observe relatively broadband mixing between the two eigenstates to generate a complete photonic bandgap. By careful analysis of the output polarisation state we report on an inherent non-reciprocity between quasi TE and TM fundamental mode cross coupling. The nature of polarisation...

  8. Motional narrowing of broadband absorption of solvatochromic indicator Betaine 30

    Energy Technology Data Exchange (ETDEWEB)

    Renge, Indrek [Institute of Physics, University of Tartu, Riia Street 142, EE51014 Tartu (Estonia)], E-mail: indrek.renge@ut.ee

    2009-05-15

    Temperature dependence of the absorption spectra of Betaine 30 (2,6-diphenyl-4-(2,4,6-triphenylpyridinio)-phenolate, widely known as Reichardt's dye) is compared with that of the broadband spectra of other dyes. The double value of the half-width (2 hwhm) of Betaine 30 absorption band between 10 and 293 K in a polymer decreases by 130{+-}20 cm{sup -1}, from 4220 to 4090 cm{sup -1}. This unprecedented narrowing with increasing temperature is ascribed to hydrogen bond symmetrization due to thermally activated proton tunneling in a pigment-solvent complex. The averaging of charge distribution along the proton coordinate causes motional narrowing of inhomogeneous width.

  9. Achieving Universal Access to Broadband

    Directory of Open Access Journals (Sweden)

    Morten FALCH

    2009-01-01

    Full Text Available The paper discusses appropriate policy measures for achieving universal access to broadband services in Europe. Access can be delivered by means of many different technology solutions described in the paper. This means a greater degree of competition and affects the kind of policy measures to be applied. The paper concludes that other policy measure than the classical universal service obligation are in play, and discusses various policy measures taking the Lisbon process as a point of departure. Available policy measures listed in the paper include, universal service obligation, harmonization, demand stimulation, public support for extending the infrastructure, public private partnerships (PPP, and others.

  10. Broadband Tuning of Optomechanical Cavities

    CERN Document Server

    Wiederhecker, Gustavo S; Lee, Sunwoo; Lipson, Michal

    2010-01-01

    We demonstrate broadband tuning of an optomechanical microcavity optical resonance by exploring the large optomechanical coupling of a double-wheel microcavity and its uniquely low mechanical stiffness. Using a pump laser with only 13 mW at telecom wavelengths we show tuning of the silicon nitride microcavity resonances over 32 nm. This corresponds to a tuning power efficiency of only 400 $\\mu$W/nm. By choosing a relatively low optical Q resonance ($\\approx$18,000) we prevent the cavity from reaching the regime of regenerative optomechanical oscillations. The static mechanical displacement induced by optical gradient forces is estimated to be as large as 60 nm.

  11. Understanding broadband over power line

    CERN Document Server

    Held, Gilbert

    2006-01-01

    Understanding Broadband over Power Line explores all aspects of the emerging technology that enables electric utilities to provide support for high-speed data communications via their power infrastructure. This book examines the two methods used to connect consumers and businesses to the Internet through the utility infrastructure: the existing electrical wiring of a home or office; and a wireless local area network (WLAN) access point.Written in a practical style that can be understood by network engineers and non-technologists alike, this volume offers tutorials on electric utility infrastru

  12. Program Predicts Broadband Noise from a Turbofan Engine

    Science.gov (United States)

    Morin, Bruce L.

    2004-01-01

    Broadband Fan Noise Prediction System (BFaNS) is a computer program that, as its name indicates, predicts the broadband noise generated by the fan stage of a turbofan engine. This noise is the sum of (1) turbulent-inflow noise, which is caused by turbulence impinging on leading edges of the fan and the fan exit guide vane and (2) self noise, which is caused by turbulence convecting past the corresponding trailing edges. The user provides input data on the fan-blade, vane, and flow-path geometries and on the mean and turbulent components of the flow field. BFaNS then calculates the turbulent-inflow noise by use of D. B. Hanson's theory, which relates sound power to the inflow turbulence characteristics and the cascade geometry. Hanson s program, BBCASCADE, is incorporated into BFaNS, wherein it is applied to the rotor and stator in a stripwise manner. The spectra of upstream and downstream sound powers radiated by each strip are summed to obtain the total upstream and downstream sound-power spectra. The self-noise contributions are calculated by S. A. L. Glegg's theory, which is also applied in a stripwise manner. The current version of BFaNS is limited to fans with subsonic tip speeds.

  13. Further Development and Assessment of a Broadband Liner Optimization Process

    Science.gov (United States)

    Nark, Douglas M.; Jones, Michael G.; Sutliff, Daniel L.

    2016-01-01

    The utilization of advanced fan designs (including higher bypass ratios) and shorter engine nacelles has highlighted a need for increased fan noise reduction over a broader frequency range. Thus, improved broadband liner designs must account for these constraints and, where applicable, take advantage of advanced manufacturing techniques that have opened new possibilities for novel configurations. This work focuses on the use of an established broadband acoustic liner optimization process to design a variable-depth, multi-degree of freedom liner for a high speed fan. Specifically, in-duct attenuation predictions with a statistical source model are used to obtain optimum impedance spectra over the conditions of interest. The predicted optimum impedance information is then used with acoustic liner modeling tools to design a liner aimed at producing impedance spectra that most closely match the predicted optimum values. The multi-degree of freedom design is carried through design, fabrication, and testing. In-duct attenuation predictions compare well with measured data and the multi-degree of freedom liner is shown to outperform a more conventional liner over a range of flow conditions. These promising results provide further confidence in the design tool, as well as the enhancements made to the overall design process.

  14. Broadband Wireline Provider Service Summary; BBRI_wirelineSum12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of broadband Internet access in Rhode Island via all wireline technologies assessed by Broadband Rhode Island. Broadband...

  15. 75 FR 10464 - Broadband Technology Opportunities Program

    Science.gov (United States)

    2010-03-08

    ... National Telecommunications and Information Administration RIN 0660-ZA28 Broadband Technology Opportunities... Technology Opportunities Program (BTOP) is extended until 5:00 p.m. Eastern Daylight Time (EDT) on March 26... Sustainable Broadband Adoption (SBA) projects. DATES: All applications for funding CCI projects must...

  16. Service Differentiation in Residential Broadband Networks

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias

    2004-01-01

    As broadband gains widespread adoption with residential users, revenue generating voice- and video-services have not yet taken off. This slow uptake is often attributed to lack of Quality of Service management in residential broadband networks. To resolve this and induce service variety, network...

  17. Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    Science.gov (United States)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Zarzana, K. J.; Rudich, Y.; Brown, S. S.

    2016-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1- reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to

  18. Diode-based microbolometer with performance enhanced by broadband metamaterial absorber.

    Science.gov (United States)

    Ma, Wei; Jia, Delin; Wen, Yongzheng; Yu, Xiaomei; Feng, Yun; Zhao, Yuejin

    2016-07-01

    This Letter reports a microbolometer integrated with a broadband metamaterial absorber (MMA) to enhance its performance, which contains series-connected silicon diodes as the temperature sensor. The broadband MMA is readily integrated into the device by introducing an array of different-sized square resonators on the silicon nitride structural layer, while the widened titanium interconnecting wires between individual diodes serve as the ground plane. In a comparative experiment, the broadband MMA was demonstrated to be superior to the ordinary silicon nitride absorber in a broad spectra range, especially in a long-wavelength IR regime, which directly leads to an increase in IR responsivity by 60%. More importantly, this enhancement in responsivity was achieved with no sacrifice of the response time due to the negligible thermal mass of the introduced resonator array. PMID:27367079

  19. Customer Churn Prediction for Broadband Internet Services

    Science.gov (United States)

    Huang, B. Q.; Kechadi, M.-T.; Buckley, B.

    Although churn prediction has been an area of research in the voice branch of telecommunications services, more focused studies on the huge growth area of Broadband Internet services are limited. Therefore, this paper presents a new set of features for broadband Internet customer churn prediction, based on Henley segments, the broadband usage, dial types, the spend of dial-up, line-information, bill and payment information, account information. Then the four prediction techniques (Logistic Regressions, Decision Trees, Multilayer Perceptron Neural Networks and Support Vector Machines) are applied in customer churn, based on the new features. Finally, the evaluation of new features and a comparative analysis of the predictors are made for broadband customer churn prediction. The experimental results show that the new features with these four modelling techniques are efficient for customer churn prediction in the broadband service field.

  20. BROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550-5418 BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lin Lin; Goegues, Ersin; Kaneko, Yuki [Faculty of Engineering and Natural Sciences, Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I Tuzla, Istanbul 34956 (Turkey); Baring, Matthew G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, Alexander; Watts, Anna L. [Astronomical Institute ' Anton Pannekoek' , University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Gruber, David; Von Kienlin, Andreas [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85748 Garching bei Mnchen (Germany); Younes, George [USRA, National Space Science and Technology Center, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Gehrels, Neil, E-mail: linlin@sabanciuniv.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5-200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT-GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550-5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550-5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550-5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.

  1. Broadband Spectral Investigations of SGR J1550-5418 Bursts

    Science.gov (United States)

    Lin, Lin; Goegues, Ersin; Baring, Matthew G.; Granot, Jonathan; Kouveliotou, Chryssa; Kaneko, Yuki; van der Horst, Alexander; Gruber, David; von Kienlin, Andreas; Younes, George; Watts, Anna L.; Gehrels, Neil

    2012-01-01

    We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5-200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT-GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550-5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550-5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550-5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.

  2. Interpreting Flux from Broadband Photometry

    CERN Document Server

    Brown, Peter J; Roming, Peter W A; Siegel, Michael

    2016-01-01

    We discuss the transformation of observed photometry into flux for the creation of spectral energy distributions and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broad-band photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by comparing in the natural units of the observations. We recommend that integrated flux measurements be made using a spectrum or spectral energy distribution whic...

  3. Broadband cloaking for flexural waves

    CERN Document Server

    Zareei, Ahmad

    2016-01-01

    The governing equation for elastic waves in flexural plates is not form invariant, and hence designing a cloak for such waves faces a major challenge. Here, we present the design of a perfect broadband cloak for flexural waves through the use of a nonlinear transformation, and by matching term-by-term the original and transformed equations. For a readily achievable flexural cloak in a physical setting, we further present an approximate adoption of our perfect cloak under more restrictive physical constraints. Through direct simulation of the governing equations, we show that this cloak, as well, maintains a consistently high cloaking efficiency over a broad range of frequencies. The methodology developed here may be used for steering waves and designing cloaks in other physical systems with non form-invariant governing equations.

  4. Tuchola County Broadband Network (TCBN)

    DEFF Research Database (Denmark)

    Zabludowski, Antoni; Dubalski, B.; Zabludowski, Lukasz;

    2012-01-01

    In the paper the designing project (plan) of Tuchola City broadband IP optical network has been presented. The extended version of network plan constitute technical part of network Feasibility Study, that it is expected to be implemented in Tuchola and be financed from European Regional Development...... Funds. The network plan presented in the paper contains both topological structure of fiber optic network as well as the active equipment for the network. In the project described in the paper it has been suggested to use Modular Cable System - MCS for passive infrastructure and Metro Ethernet...... technology for active equipment. The presented solution provides low cost of construction (CAPEX), ease of implementation of the network and low operating cost (OPEX). Moreover the parameters of installed Metro Ethernet switches in the network guarantee the scalability of the network for at least 10 years....

  5. Omnidirectional and broadband absorption enhancement from trapezoidal Mie resonators in semiconductor metasurfaces.

    Science.gov (United States)

    Pala, Ragip A; Butun, Serkan; Aydin, Koray; Atwater, Harry A

    2016-01-01

    Light trapping in planar ultrathin-film solar cells is limited due to a small number of optical modes available in the thin-film slab. A nanostructured thin-film design could surpass this limit by providing broadband increase in the local density of states in a subwavelength volume and maintaining efficient coupling of light. Here we report a broadband metasurface design, enabling efficient and broadband absorption enhancement by direct coupling of incoming light to resonant modes of subwavelengthscale Mie nanoresonators defined in the thin-film active layer. Absorption was investigated both theoretically and experimentally in prototypes consisting of lithographically patterned, two-dimensional periodic arrays of silicon nanoresonators on silica substrates. A crossed trapezoid resonator shape of rectangular cross section is used to excite broadband Mie resonances across visible and near-IR spectra. Our numerical simulations, optical absorption measurements and photocurrent spectral response measurements demonstrate that crossed trapezoidal Mie resonant structures enable angle-insensitive, broadband absorption. A short circuit current density of 12.0 mA/cm(2) is achieved in 210 nm thick patterned Si films, yielding a 4-fold increase compared to planar films of the same thickness. It is suggested that silicon metasurfaces with Mie resonator arrays can provide useful insights to guide future ultrathin-film solar cell designs incorporating nanostructured thin active layers. PMID:27641965

  6. Broadband spectroscopic lidar for SWIR/MWIR detection of gaseous pollutants in air

    Science.gov (United States)

    Lambert-Girard, Simon; Hô, Nicolas; Bourliaguet, Bruno; Lemieux, Dany; Piché, Michel; Babin, François

    2012-11-01

    A broadband SWIR/MWIR spectroscopic lidar for detection of gaseous pollutants in air is presented for doing differential optical absorption spectroscopy (DOAS). One of the distinctive parts of the lidar is the use of a picosecond PPMgO:LN OPG (optical parametric generator) capable of generating broadband (10 to plane array used in the output plane of the grating spectrograph of the lidar system. The whole of the returned spectra is measured, within a very short time gate, at every pulse and at a resolution of a few tenths to a few nm. Light is collected by a telescope with variable focus for maximum coupling of the return to the spectrograph. Since all wavelengths are emitted and received simultaneously, the atmosphere is "frozen" during the path integrated measurement and hopefully reduces the baseline drift problem encountered in many broadband scanning approaches. The resulting path integrated gas concentrations are retrieved by fitting the molecular absorption features present in the measured spectra. The use of broadband pulses of light and of DOAS fitting procedures make it also possible to measure more than one gas at a time, including interferents. The OPG approach enables the generation of moderate FWHM continua with high spectral energy density and tunable to absorption features of a great number of molecules. Proposed follow-on work and applications will also be presented.

  7. Highly coherent modeless broadband semiconductor laser.

    Science.gov (United States)

    Sellahi, M; Myara, M; Beaudoin, G; Sagnes, I; Garnache, A

    2015-09-15

    We report on the highly coherent modeless broadband continuous wave operation of a semiconductor vertical-external-cavity-surface-emitting laser. The laser design is based on a frequency-shifted-feedback scheme provided by an acousto-optic frequency shifter inserted in a linear or a ring traveling wave cavity. The gain mirror is a GaAs-based multiple quantum well structure providing large gain at 1.07 μm. This laser exhibits a coherent optical spectrum over 1.27 nm (330 GHz) bandwidth, with 70 mW output power and a high beam quality. The light polarization is linear (>30  dB extinction ratio). The laser dynamics exhibits a low intensity noise close to class A regime, with a ∼1.5  MHz cutoff frequency. The frequency noise spectral density shows a first-order low-pass like shape (130 kHz cutoff) leading to a Gaussian shape for homodyne interferometric signals. The measured beat width is ≃54  kHz and the coherence time of ∼19  μs. No nonlinear effects are observed, showing dynamics very close to theory. PMID:26371921

  8. Designing broadband plasmonic nanoantennas for ultrasensing

    Science.gov (United States)

    Yi, Zhenhuan; Wang, Kai; Voronine, Dmitri V.; Traverso, Andrew; Sokolov, Alexei

    2011-03-01

    Various designs of broadband plasmonic nanoantennas made of gold and silver nanospheres are considered and optimized for ultrasensitive spectroscopic applications. The simulated nanostructures show a broadband optical response which may be tuned by varying the size, position and composition of nanospheres. Near-field enhancement in nanoantenna hot spots is analyzed and compared with previous literature results in the case of a fractal plasmonic nanolens. Broadband plasmonic nanoantennas may allow detecting ultrasmall concentrations of toxic materials and may be used for decoding DNA and for ultrafast nanophotonics applications.

  9. Analyzing Broadband Divide in the Farming Sector

    DEFF Research Database (Denmark)

    Jensen, Michael; Gutierrez Lopez, Jose Manuel; Pedersen, Jens Myrup

    2013-01-01

    Agriculture industry has been evolving for centuries. Currently, the technological development of Internet oriented farming tools allows to increase the productivity and efficiency of this sector. Many of the already available tools and applications require high bandwidth in both directions...... difference between the broadband availability for farms and the rest of the households/buildings the country. This divide may be slowing down the potential technological development of the farming industry, in order to keep their competitiveness in the market. Therefore, broadband development in rural areas...... could be one of the points to focus in a near future broadband access plans....

  10. Broadband terahertz time-domain spectroscopy : crystalline and glassy drug materials

    International Nuclear Information System (INIS)

    Low-energy IR active modes of glassy and crystalline drug materials were studied by the broadband Terahertz Time Domain Spectroscopy (THz-TDS) in the frequency range from 0.5 to 6.5 THz using a Cherenkov type THz generator. In order to determine the real and imaginary parts of complex dielectric constant, all samples were measured by the transmission using a pure pellet without mixing polyethylene. For glassy indomethacine, the broadband THz spectrum of real part of dielectric constant shows step-wise decrease with the increase of frequency, while the imaginary part shows a broad peak at about 3 THz reflecting quenched glassy disordered structure. The observed spectra of crystalline racemic ketoprofen show the noncoincidence of peak frequencies between low-frequency Raman scattering and THz absorbance spectra. It can be attributed to the fact that the mutual exclusion principle between Raman and IR activities holds below 6 THz

  11. Broadband photon time of flight spectroscopy: advanced spectroscopic analysis for ensuring safety and performance of pharmaceutical tablets

    DEFF Research Database (Denmark)

    Kamran, Faisal; Nielsen, Otto Højager Attermann; Andersson-Engels, Stefan;

    2013-01-01

    We report on extended spectroscopic analysis of pharmaceutical tablets performed with broadband photon time-of-flight absorption/scaring spectroscopy. Precise monitoring of absorption and scattering spectra enables cost-efficient monitoring of key safety and performance parameters of the drugs....

  12. Impact of temporal, spatial and cascaded effects on the pulse formation in ultra-broadband parametric amplifiers.

    Science.gov (United States)

    Lang, T; Harth, A; Matyschok, J; Binhammer, T; Schultze, M; Morgner, U

    2013-01-14

    A 2 + 1 dimensional nonlinear pulse propagation model is presented, illustrating the weighting of different effects for the parametric amplification of ultra-broadband spectra in different regimes of energy scaling. Typical features in the distribution of intensity and phase of state-of-the-art OPA-systems can be understood by cascaded spatial and temporal effects. PMID:23388988

  13. Broadband 2D Electronic Spectroscopy Reveals Coupling Between Dark 1Bu- State of Carotenoid and Qx State of Bacteriochlorophyll

    Directory of Open Access Journals (Sweden)

    Scholes Gregory D.

    2013-03-01

    Full Text Available The study of LH2 protein of purple bacteria by broadband 2D electronic spectroscopy is presented. The dark 1Bu- carotenoid state is directly observed in 2D spectra and its role in carotenoid-bacteriochlorophyll interaction is discussed.

  14. Impact of temporal, spatial and cascaded effects on the pulse formation in ultra-broadband parametric amplifiers.

    Science.gov (United States)

    Lang, T; Harth, A; Matyschok, J; Binhammer, T; Schultze, M; Morgner, U

    2013-01-14

    A 2 + 1 dimensional nonlinear pulse propagation model is presented, illustrating the weighting of different effects for the parametric amplification of ultra-broadband spectra in different regimes of energy scaling. Typical features in the distribution of intensity and phase of state-of-the-art OPA-systems can be understood by cascaded spatial and temporal effects.

  15. 47 CFR 90.1405 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Shared wireless broadband network. 90.1405... broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private Partnership must be designed to meet requirements associated with a nationwide, public safety broadband network....

  16. Generation of broadband spontaneous parametric fluorescence using multiple bulk nonlinear crystals

    OpenAIRE

    Okano, Masayuki; Okamoto, Ryo; TANAKA, Akira; Subashchandran, Shanthi; Takeuchi, Shigeki

    2012-01-01

    We propose a novel method for generating broadband spontaneous parametric fluorescence by using a set of bulk nonlinear crystals (NLCs). We also demonstrate this scheme experimentally. Our method employs a superposition of spontaneous parametric fluorescence spectra generated using multiple bulk NLCs. A typical bandwidth of 160 nm (73 THz) with a degenerate wavelength of 808 nm was achieved using two beta-barium-borate (BBO) crystals, whereas a typical bandwidth of 75 nm (34 THz) was realized...

  17. Seismic spectra of events at regional distances

    International Nuclear Information System (INIS)

    About 40 underground nuclear explosions detonated at the Nevada Test Site (NTS) were chosen for analysis of their spectra and any relationships they might have to source parameters such as yield, depth of burial, etc. The sample covered a large yield range (less than 20 kt to greater than 1 Mt). Broadband (0.05 to 20 Hz) data recorded by the four-station seismic network operated by Lawrence Livermore Laboratory were analyzed in a search for unusual explosion signatures in their spectra. Long time windows (total wave train) as well as shorter windows (for instance, P/sub n/) were used as input to calculate the spectra. Much variation in the spectra of the long windows is typical although some gross features are similar, such as a dominant peak in the microseismic window. The variation is such that selection of corner frequencies is impractical and yield scaling could not be determined. Spectra for one NTS earthquake showed more energy in the short periods (less than 1 sec) as well as in the long periods (greater than 8 sec) compared to those for NTS explosions

  18. Nanophotonic Design for Broadband Light Management

    Energy Technology Data Exchange (ETDEWEB)

    Kosten, Emily; Callahan, Dennis; Horowitz, Kelsey; Pala, Ragip; Atwater, Harry

    2014-10-13

    We describe nanophotonic design approaches for broadband light management including i) crossed-trapezoidal Si structures ii) Si photonic crystal superlattices, and iii) tapered and inhomogeneous diameter III-V/Si nanowire arrays.

  19. Wireless Broadband Access and Accounting Schemes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, we propose two wireless broadband access and accounting schemes. In both schemes, the accounting system adopts RADIUS protocol, but the access system adopts SSH and SSL protocols respectively.

  20. Broadband detection of squeezed vacuum A spectrum of quantum states

    CERN Document Server

    Breitenbach, G; Schiller, S; Mlynek, J; Breitenbach, Gerd; Illuminati, Fabrizio; Schiller, Stephan; Mlynek, Jurgen

    1998-01-01

    We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a "spectrum" of density matrices and Wigner functions is obtained. The recorded states show a smooth transition from the squeezed vacuum to a vacuum state. In the time domain we evaluated the first order correlation function of the squeezed output field, showing good agreement with the theory.

  1. Enhancements to INO's broadband SWIR/MWIR spectroscopic lidar

    Science.gov (United States)

    Lambert-Girard, Simon; Babin, François; Allard, Martin; Piché, Michel

    2013-09-01

    Recent advances in the INO broadband SWIR/MWIR spectroscopic lidar will be presented. The system is designed for the detection of gaseous pollutants via active infrared differential optical absorption spectroscopy (DOAS). Two distinctive features are a sub-nanosecond PPMgO:LN OPG capable of generating broadband (10 to plane array used in the output plane of a grating spectrograph. The operation consists in closely gating the returns from back-scattering off topographic features, and is thus, for now, a path integrated measurement. All wavelengths are emitted and received simultaneously, for low concentration measurements and DOAS fitting methods are then applied. The OPG approach enables the generation of moderate FWHM continua with high spectral energy density and tunable to absorption features of many molecules. Recent measurements demonstrating a minimum sensitivity of 10 ppm-m for methane around 3.3 μm with ˜ 2 mW average power in less than 10 seconds will be described. Results of enhancements to the laser source using small or large bandwidth seeds constructed from telecom off-the-shelf components indicate that the OPG output spectral energy density can have controllable spectral widths and shapes. It also has a slightly more stable spectral shape from pulse to pulse than without the seed (25 % enhancement). Most importantly, the stabilized output spectra will allow more sensitive measurements.

  2. Anomalous Signals Prior to Wenchuan Earthquake Detected by Superconducting Gravimeter and Broadband Seismometers Records

    Institute of Scientific and Technical Information of China (English)

    Wenbin Shen; Dijin Wang; Cheinway Hwang

    2011-01-01

    Using 1 Hz sampling records at one superconducting gravimeter (SG) station and 11 broadband seismometer stations,we found anomalous signals prior to the 2008 Wenchuan(汶川)earthquake event.The tides are removed from the original SG records to obtain the gravity residuals.Applying the Hilbert-Huang transform (HHT) and the wavelet analysis to the SG gravity residuals leads to time-frequency spectra,which suggests that there is an anomalous signal series around 39 h prior to the event.The period and the magnitude of the anomalous signal series are about 8 s and 3×10-8 m/s2 (3 μGal),respectively.In another aspect,applying HHT analysis technique to 11 records at broadband seismometer stations shows that most of them contain anomalous signals prior to the Wenchuan event,and the marginal spectra of 8 inland stations show an apparent characteristic of double peaks in anomalous days compared to the only one peak of the marginal spectra in quiet days.Preliminary investigations suggest that the anomalous signals prior to the earthquake are closely related to the low-frequency earthquake (LFE).We concluded that the SG data as well as the broadband seismometers records might be significant information sources in detecting the anomalous signals prior to large earthquakes.

  3. Evaluation of arctic broadband surface radiation measurements

    OpenAIRE

    Matsui, N.; C. N. Long; J. Augustine; Halliwell, D.; T. Uttal; Longenecker, D.; O. Nievergall; Wendell, J.; Albee, R.

    2011-01-01

    The Arctic is a challenging environment for making in-situ radiation measurements. A standard suite of radiation sensors is typically designed to measure the total, direct and diffuse components of incoming and outgoing broadband shortwave (SW) and broadband thermal infrared, or longwave (LW) radiation. Enhancements can include various sensors for measuring irradiance in various narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are...

  4. Multi-Mode Broadband Patch Antenna

    Science.gov (United States)

    Romanofsky, Robert R. (Inventor)

    2001-01-01

    A multi-mode broad band patch antenna is provided that allows for the same aperture to be used at independent frequencies such as reception at 19 GHz and transmission at 29 GHz. Furthermore, the multi-mode broadband patch antenna provides a ferroelectric film that allows for tuning capability of the multi-mode broadband patch antenna over a relatively large tuning range. The alternative use of a semiconductor substrate permits reduced control voltages since the semiconductor functions as a counter electrode.

  5. Broadband circularly polarized antennas for UHF SATCOM

    OpenAIRE

    Tekin, İbrahim; Tekin, Ibrahim; Manzhura, Oksana; Niver, Edip

    2011-01-01

    Novel circularly polarized (CP) antenna configurations derived from Moxon type antenna (bent dipole element over a ground plane) for broadband VHF SATCOM applications. A sequence of topologies starting from a single vertical element to two vertical elements of the Moxon arms, then widened strip arm elements were studied. Further, arms were widened to bow tie structures with bents at 900.for achieving broadband operation. Bow tie elements were further split and optimized at a certain angle to...

  6. Broadband mode conversion via gradient index metamaterials.

    Science.gov (United States)

    Wang, HaiXiao; Xu, YaDong; Genevet, Patrice; Jiang, Jian-Hua; Chen, HuanYang

    2016-04-21

    We propose a design for broadband waveguide mode conversion based on gradient index metamaterials (GIMs). Numerical simulations demonstrate that the zeroth order of transverse magnetic mode or the first order of transverse electric mode (TM0/TE1) can be converted into the first order of transverse magnetic mode or the second order of transverse electric mode (TM1/TE2) for a broadband of frequencies. As an application, an asymmetric propagation is achieved by integrating zero index metamaterials inside the GIM waveguide.

  7. Sequencing BPS Spectra

    CERN Document Server

    Gukov, Sergei; Saberi, Ingmar; Stosic, Marko; Sulkowski, Piotr

    2015-01-01

    This paper provides both a detailed study of color-dependence of link homologies, as realized in physics as certain spaces of BPS states, and a broad study of the behavior of BPS states in general. We consider how the spectrum of BPS states varies as continuous parameters of a theory are perturbed. This question can be posed in a wide variety of physical contexts, and we answer it by proposing that the relationship between unperturbed and perturbed BPS spectra is described by a spectral sequence. These general considerations unify previous applications of spectral sequence techniques to physics, and explain from a physical standpoint the appearance of many spectral sequences relating various link homology theories to one another. We also study structural properties of colored HOMFLY homology for links and evaluate Poincar\\'e polynomials in numerous examples. Among these structural properties is a novel "sliding" property, which can be explained by using (refined) modular $S$-matrix. This leads to the identifi...

  8. Global characterization of seismic noise with broadband seismometers

    CERN Document Server

    Coughlin, Michael William

    2012-01-01

    In this paper, we present an analysis of seismic spectra that were calculated from all broadband channels (BH?) made available through IRIS, NIED F-net and Orfeus servers covering the past five years and beyond. A general characterization of the data is given in terms of spectral histograms and data-availability plots. We show that the spectral information can easily be categorized in time and regions. Spectral histograms indicate that seismic stations exist in Africa, Australia and Antarctica that measure spectra significantly below the global low-noise models above 1 Hz. We investigate world-wide coherence between the seismic spectra and other data sets like proximity to cities, station elevation, earthquake frequency, and wind speeds. Elevation of seismic stations in the US is strongly anti-correlated with seismic noise near 0.2 Hz and again above 1.5 Hz. Urban settlements are shown to produce excess noise above 1 Hz, but correlation curves look very different depending on the region. It is shown that wind...

  9. UHB Engine Fan Broadband Noise Reduction Study

    Science.gov (United States)

    Gliebe, Philip R.; Ho, Patrick Y.; Mani, Ramani

    1995-01-01

    A study has been completed to quantify the contribution of fan broadband noise to advanced high bypass turbofan engine system noise levels. The result suggests that reducing fan broadband noise can produce 3 to 4 EPNdB in engine system noise reduction, once the fan tones are eliminated. Further, in conjunction with the elimination of fan tones and an increase in bypass ratio, a potential reduction of 7 to 10 EPNdB in system noise can be achieved. In addition, an initial assessment of engine broadband noise source mechanisms has been made, concluding that the dominant source of fan broadband noise is the interaction of incident inlet boundary layer turbulence with the fan rotor. This source has two contributors, i.e., unsteady life dipole response and steady loading quadrupole response. The quadrupole contribution was found to be the most important component, suggesting that broadband noise reduction can be achieved by the reduction of steady loading field-turbulence field quadrupole interaction. Finally, for a controlled experimental quantification and verification, the study recommends that further broadband noise tests be done on a simulated engine rig, such as the GE Aircraft Engine Universal Propulsion Simulator, rather than testing on an engine statically in an outdoor arena The rig should be capable of generating forward and aft propagating fan noise, and it needs to be tested in a large freejet or a wind tunnel.

  10. Broadband direct RF digitization receivers

    CERN Document Server

    Jamin, Olivier

    2014-01-01

    This book discusses the trade-offs involved in designing direct RF digitization receivers for the radio frequency and digital signal processing domains.  A system-level framework is developed, quantifying the relevant impairments of the signal processing chain, through a comprehensive system-level analysis.  Special focus is given to noise analysis (thermal noise, quantization noise, saturation noise, signal-dependent noise), broadband non-linear distortion analysis, including the impact of the sampling strategy (low-pass, band-pass), analysis of time-interleaved ADC channel mismatches, sampling clock purity and digital channel selection. The system-level framework described is applied to the design of a cable multi-channel RF direct digitization receiver. An optimum RF signal conditioning, and some algorithms (automatic gain control loop, RF front-end amplitude equalization control loop) are used to relax the requirements of a 2.7GHz 11-bit ADC. A two-chip implementation is presented, using BiCMOS and 65nm...

  11. Interpreting Flux from Broadband Photometry

    Science.gov (United States)

    Brown, Peter J.; Breeveld, Alice; Roming, Peter W. A.; Siegel, Michael

    2016-10-01

    We discuss the transformation of observed photometry into flux for the creation of spectral energy distributions (SED) and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broadband photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by forward modeling the spectrum into the count rates or magnitudes of the observations. We recommend that integrated flux measurements be made using a spectrum or SED which is consistent with the multi-band photometry rather than converting individual photometric measurements to flux densities, linearly interpolating between the points, and integrating. We also highlight some specific areas where the UV flux can be mischaracterized.

  12. Ultra-broadband photonic internet

    Science.gov (United States)

    Romaniuk, Ryszard S.

    2011-06-01

    In this paper, there is presented a review of our today's understanding of the ultimately broadband photonic Internet. A simple calculation is presented showing the estimate of the throughput of the core photonic network branches. Optoelectronic components, circuits, systems and signals, together with analogous electronic entities and common software layers, are building blocks of the contemporary Internet. Participation of photonics in development of the physical layer in the future Internet will probably increase. The photonics leads now to a better usage of the available bandwidth (increase of the spectral efficiency measured in Bit/s/Hz), increase in the transmission rate (from Gbps, via Tbps up to probably Pbps), increase in the transmission distance without signal regeneration (in distortion compensated active optical cables), increase in energy/power efficiency measured in W/Gbps, etc. Photonics may lead, in the future, to fully transparent optical networks and, thus, to essential increase in bandwidth and network reliability. It is expected that photonics (with biochemistry, electronics and mechatronics) may build psychological and physiological interface for humans to the future global network. The following optical signal multiplexing methods were considered, which are possible without O/E/O conversion: TDM-OTDM, FDM-CO-OFDM, OCDM-OCDMA, WDM-DWDM.

  13. Broadband stimulated Raman microscopy with 0.1  ms pixel acquisition time.

    Science.gov (United States)

    Czerwinski, Lars; Nixdorf, Jakob; Florio, Giuseppe Di; Gilch, Peter

    2016-07-01

    Femtosecond stimulated Raman microscopy (FSRM) is a nonlinear technique for rapid broadband Raman imaging. It utilizes a few femtosecond probe pulse and a narrow bandwidth pump pulse. Using a fast (20 kHz) multi-channel detector, stimulated Raman spectra can be recorded with an acquisition time as short as 0.1 ms. In this Letter, spectra of neat benzonitrile at different acquisition speeds are presented to benchmark the FSRM setup. Furthermore, chemical maps of a multi-phase polymer blend are recorded using the fastest acquisition rate possible with the current instrument. PMID:27367091

  14. Fiber Optic Continuous Liquid Sensor for Cryogenic Propellant Gauging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Broadband Photonics Incorporated proposes to develop a patent-pending fiber optic continuous liquid sensor for low-thrust level settled mass gauging with...

  15. Design of a continuous resistively loaded monopole antenna

    OpenAIRE

    Darwish, Abd El Aziz Mohamed; Janaswamy, Ramakrishna

    1993-01-01

    Hallen's integral equation with continuous resistive loading is used to design a broadband monopole antenna. The resistive profile is different from that of the well known Wu-King profile and results in a higher efficiency compared to the latter. An optimization function for determining the optimal continuous resistive load of the monopole antenna in order to satisfy the broadband property is constructed. Simplex method is used to perform the optimization. The integral equation is solved by t...

  16. 75 FR 33303 - Comment Sought on Measurement of Mobile Broadband Network Performance and Coverage

    Science.gov (United States)

    2010-06-11

    ... Measurement of Mobile Broadband Network Performance and Coverage AGENCY: Federal Communications Commission... voluntary self- reporting of network performance and coverage. DATES: Comments are due on or before July 1... user-generated data on network performance and coverage, and continue to work with...

  17. The monterey bay broadband ocean bottom seismic observatory

    Directory of Open Access Journals (Sweden)

    R. Uhrhammer

    2006-06-01

    Full Text Available We report on the installation of a long-term buried ocean-floor broadband seismic station (MOBB in Monterey Bay, California (USA, 40km off-shore, at a water depth of 1000 m. The station was installed in April 2002 using a ship and ROV, in a collaborative effort between the Monterey Bay Aquarium Research Institute (MBARI and the Berkeley Seismological Laboratory (BSL. The station is located on the western side of the San Gregorio Fault, a major fault in the San Andreas plate boundary fault system. In addition to a 3-component CMG-1T seismometer package, the station comprises a current meter and Differential Pressure Gauge, both sampled at high-enough frequency (1 Hz to allow the study of relations between background noise on the seismometers and ocean waves and currents. The proximity of several land-based broadband seismic stations of the Berkeley Digital Seismic Network allows insightful comparisons of land/ocean background seismic noise at periods relevant to regional and teleseismic studies. The station is currently autonomous. Recording and battery packages are exchanged every 3 months during scheduled one day dives. Ultimately, this station will be linked to shore using continuous telemetry (cable and/or buoy and will contribute to the earthquake notification system in Northern California. We present examples of earthquake and noise data recorded during the first 6 months of operation of MOBB. Lessons learned from these and continued recordings will help understand the nature and character of background noise in regional off-shore environments and provide a reference for the installation of future off-shore temporary and permanent broadband seismic stations.

  18. The broad-band X-ray spectrum of Cygnus X-2

    Science.gov (United States)

    Pravdo, S. H.

    1983-01-01

    Cygnus X-2 was observed with the broad-band X-ray spectroscopy experiment, HEAO 1 A-2, in the energy range 0.4-18 keV for four intervals of approximately 31 s over the course of 5 days in 1977. The spectra can be adequately represented by single-temperature thermal bremmstrahlung continua with temperatures ranging from 3.7 x 10 to the 7th K to 6.4 x 10 to the 7th K. An examination of the spectra and the spectra-luminosity relationship effectively rules out one degenerate dwarf model for the X-ray emission. The far-UV continuum emission could be dominated by this continuum component during X-ray high states, an effect which would be detected in optical UV line observations. A Comptonized X-ray cloud around a neutron star remains a viable model for the observed X-ray spectra.

  19. Application of multimedia services in the broadband environment to improve logistic needs of the army

    Directory of Open Access Journals (Sweden)

    Radiša R. Stefanović

    2012-07-01

    Full Text Available The paper analyzes the flow of some multimedia services, and points to the possibility of applying some of the services in the broadband environment to improve the logistic needs of the army. The need to convey information in different forms (from text, data, graphics, still pictures to video motion pictures is increasing continually. Requests for information transfer in high resolution require increasing the flow to several dozens of Mb/s. Broadband represents the platform for a wide range of multimedia services. Each multimedia service requires a certain flow which can be partially decreased with advanced coding techniques.

  20. Broadband Fan Noise Prediction System for Turbofan Engines. Volume 3; Validation and Test Cases

    Science.gov (United States)

    Morin, Bruce L.

    2010-01-01

    Pratt & Whitney has developed a Broadband Fan Noise Prediction System (BFaNS) for turbofan engines. This system computes the noise generated by turbulence impinging on the leading edges of the fan and fan exit guide vane, and noise generated by boundary-layer turbulence passing over the fan trailing edge. BFaNS has been validated on three fan rigs that were tested during the NASA Advanced Subsonic Technology Program (AST). The predicted noise spectra agreed well with measured data. The predicted effects of fan speed, vane count, and vane sweep also agreed well with measurements. The noise prediction system consists of two computer programs: Setup_BFaNS and BFaNS. Setup_BFaNS converts user-specified geometry and flow-field information into a BFaNS input file. From this input file, BFaNS computes the inlet and aft broadband sound power spectra generated by the fan and FEGV. The output file from BFaNS contains the inlet, aft and total sound power spectra from each noise source. This report is the third volume of a three-volume set documenting the Broadband Fan Noise Prediction System: Volume 1: Setup_BFaNS User s Manual and Developer s Guide; Volume 2: BFaNS User s Manual and Developer s Guide; and Volume 3: Validation and Test Cases. The present volume begins with an overview of the Broadband Fan Noise Prediction System, followed by validation studies that were done on three fan rigs. It concludes with recommended improvements and additional studies for BFaNS.

  1. Estimation of broadband emissivity (8-12 um) from ASTER data by using RM-NN.

    Science.gov (United States)

    Mao, K B; Ma, Y; Shen, X Y; Li, B P; Li, C Y; Li, Z L

    2012-08-27

    Land surface window emissivity is a key parameter for estimating the longwave radiative budget. The combined radiative transfer model (RM) with neural network (NN) algorithm is utilized to directly estimate the window (8-12 um) emissivity from the brightness temperature of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with 90 m spatial resolution. Although the estimation accuracy is very high when the broadband emissivity is estimated from AST05 (ASTER Standard Data Product) by using regression method, the accuracy of AST05 is about ± 0.015 for 86 spectra which is determined by the atmosphere correction for ASTER 1B data. The MODTRAN 4 is used to simulate the process of radiance transfer, and the broadband emissivity is directly estimated from the brightness temperature of ASTER 1B data at satellite. The comparison analysis indicates that the RM-NN is more competent to estimate broadband emissivity than other method when the brightness temperatures of band 11, 12, 13, 14 are made as input nodes of dynamic neural network. The estimation average accuracy is about 0.009, and the estimation results are not sensitive to instrument noise. The RM-NN is applied to extract broadband emissivity from an image of ASTER 1B data in China, and the comparison against a classification based multiple bands with 15 m spatial resolution shows that the estimation results from RM-NN are very good.

  2. Estimation of broadband emissivity (8-12 um) from ASTER data by using RM-NN.

    Science.gov (United States)

    Mao, K B; Ma, Y; Shen, X Y; Li, B P; Li, C Y; Li, Z L

    2012-08-27

    Land surface window emissivity is a key parameter for estimating the longwave radiative budget. The combined radiative transfer model (RM) with neural network (NN) algorithm is utilized to directly estimate the window (8-12 um) emissivity from the brightness temperature of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with 90 m spatial resolution. Although the estimation accuracy is very high when the broadband emissivity is estimated from AST05 (ASTER Standard Data Product) by using regression method, the accuracy of AST05 is about ± 0.015 for 86 spectra which is determined by the atmosphere correction for ASTER 1B data. The MODTRAN 4 is used to simulate the process of radiance transfer, and the broadband emissivity is directly estimated from the brightness temperature of ASTER 1B data at satellite. The comparison analysis indicates that the RM-NN is more competent to estimate broadband emissivity than other method when the brightness temperatures of band 11, 12, 13, 14 are made as input nodes of dynamic neural network. The estimation average accuracy is about 0.009, and the estimation results are not sensitive to instrument noise. The RM-NN is applied to extract broadband emissivity from an image of ASTER 1B data in China, and the comparison against a classification based multiple bands with 15 m spatial resolution shows that the estimation results from RM-NN are very good. PMID:23037062

  3. Broadband and luminous extinction coefficients in a clean and dry atmosphere

    Science.gov (United States)

    Kocifaj, Miroslav

    2016-04-01

    The extinction coefficient as a function of optical air mass has been persistently used for many years in order to model both direct normal irradiance and illuminance (DNI). Nevertheless, such a dependence is only approximate, simply a convenient, but inaccurate application in monochromatic radiative transfer theories. The relationship between these characteristics originates from the point source exponential law incorrectly used for broadband radiation and, the set of empirical formulae used for broadband and luminous extinction coefficients have no preferred model. Therefore, in this paper we explain the fundamentals of broadband (ae) and luminous (av) extinction coefficients for a clean and dry atmosphere and introduce general formulae which originate from heuristic analytical derivation that produce exact formulae, free of any random or systematic errors which can arise from numerical integration or processing of experimental data. Another advantage is that each parameter used in new formulae for ae or av has a theoretical base, therefore optimum by delineation. The analytical formulae could replace those routinely used in modelling DNI for broadband spectra (including daylight).

  4. Participation in the broadband society in Denmark

    DEFF Research Database (Denmark)

    Falch, Morten; Henten, Anders; Skouby, Knud Erik

    2009-01-01

    The purpose of the paper is to provide an empirical overview of broadband developments in Denmark. The overview includes sections on coverage and penetration, connection speeds, retail prices, competition, interconnection prices, and residential access to Internet. The documentation shows...... passed the threshold set by the EU with respect to the relevance of initiating a discussion on the implementation of a universal service obligation on broadband. As documented in the paper, there are groups among primarily the elderly and the unemployed who do not have Internet access. Their own...... that Denmark is doing well in most international comparisons, but retail prices are still relatively high and connection speeds are lower than the best performing countries. In terms of households, approximately three quarters have broadband access. Denmark - and a number of other countries as well - has thus...

  5. Policy factors affecting broadband development in Poland

    DEFF Research Database (Denmark)

    Henten, Anders; Windekilde, Iwona Maria

    2014-01-01

    ’s telecommunications market with the European market. The market reflects all the global trends, a gradually growing significance of mobile telecommunications services, broadband Internet access, construction of offers directed towards clients’ needs, and a strong trend towards market consolidation, which...... will gradually change the previous balance of power. The specific problem of the Polish market is its very poor infrastructure development and the lack of competitors on the fixed market. This translates into limited access to services for end users particularly in the rural areas. A much lower level...... and discuss broadband access development in Poland and the policy factors influencing this development as well as to examine national strategies used to stimulate service and infrastructure competition in Poland. There are, indeed, many other factors affecting broadband development such as the income level...

  6. Broadband absorption engineering of hyperbolic metafilm patterns

    Science.gov (United States)

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-03-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experimental realization of an on-chip broadband super absorber structure based on hyperbolic metamaterial waveguide taper array with strong and tunable absorption profile from near-infrared to mid-infrared spectral region. The ability to efficiently produce broadband, highly confined and localized optical fields on a chip is expected to create new regimes of optical/thermal physics, which holds promise for impacting a broad range of energy technologies ranging from photovoltaics, to thin-film thermal absorbers/emitters, to optical-chemical energy harvesting.

  7. Broadband Polarizers Based on Graphene Metasurfaces

    CERN Document Server

    Guo, Tianjing

    2016-01-01

    We present terahertz (THz) metasurfaces based on aligned rectangular graphene patches placed on top of a dielectric layer to convert the transmitted linearly polarized waves to circular or elliptical polarized radiation. Our results lead to the design of an ultrathin broadband THz quarter-wave plate. In addition, ultrathin metasurfaces based on arrays of L-shaped graphene periodic patches are demonstrated to achieve broadband cross-polarization transformation in reflection and transmission. The proposed metasurface designs have tunable responses and are envisioned to become the building blocks of several integrated THz systems.

  8. Broadband Multilayered Array Antenna with EBG Reflector

    Directory of Open Access Journals (Sweden)

    P. Chen

    2013-01-01

    Full Text Available Most broadband microstrip antennae are implemented in the form of slot structure or laminate structure. The impedance bandwidth is broadened, but meanwhile, the sidelobe of the directivity pattern and backlobe level are enlarged. A broadband stacked slot coupling microstrip antenna array with EBG structure reflector is proposed. Test results indicate that the proposed reflector structure can effectively improve the directivity pattern of stacked antenna and aperture coupled antenna, promote the front-to-back ratio, and reduce the thickness of the antenna. Therefore, it is more suitable to be applied as an airborne antenna.

  9. Broadband External-Cavity Diode Laser

    Science.gov (United States)

    Pilgrim, Jeffrey S.

    2005-01-01

    A broadband external-cavity diode laser (ECDL) has been invented for use in spectroscopic surveys preparatory to optical detection of gases. Heretofore, commercially available ECDLs have been designed, in conjunction with sophisticated tuning assemblies, for narrow- band (and, typically, single-frequency) operation, as needed for high sensitivity and high spectral resolution in some gas-detection applications. However, for preparatory spectroscopic surveys, high sensitivity and narrow-band operation are not needed; in such cases, the present broadband ECDL offers a simpler, less-expensive, more-compact alternative to a commercial narrowband ECDL.

  10. Complex Spectra in Fusion Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hellermann, M.G. von; Jaspers, R. [FOM-Institute for Plasma Physics Rijnhuizen, Nieuwegein (Netherlands); Bertschinger, G.; Biel, W.; Marchuk, O. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Plasmaphysik; Giroud, C.; Zastrow, K.D. [UKAEA Culham Laboratory Euratom Association, Abingdon (United Kingdom); Jupen, C. [Univ. of Lund (Sweden). Physics Dept.; O' Mullane, M.; Summers, H.P.; Whiteford, A. [Univ. of Strathclyde, Glasgow (United Kingdom). Applied Physics Dept.

    2005-12-15

    The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development of sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment of the plasma environment. The successful merging of the two worlds has led to routine diagnostic procedures which have contributed enormously to the understanding of underlying plasma processes and also to a wide acceptance of spectroscopy as a reliable diagnostic method. In this paper three characteristic types of spectra of current and continuing interest are presented. The first is that of medium/heavy species with many ionisation stages revealed in survey VUV and XUV spectra. Such species occur as control gases, as wall materials, as ablated heavy species and possible as layered wall dopants for monitoring erosion. The spectra are complex with line-like and quasi-continuum regions and are amenable to advanced ?pattern recognition' methods. The second type is of few electron, highly ionised systems observed as line-of-sight integrated passive emission spectra in the soft X-ray region. They are analysed successfully in terms of plasma parameters through matching of observation with predicted synthetic spectra. Examples used here include highly resolved helium-like emission spectra of argon, iron and titanium observed on the tokamaks TEXTOR and Tore Supra. The third type, and the emphasis of this work, comprises spectra linked to active beam spectroscopy, that is, charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES). In this case, a complex spectrum is again composed of a (usually) dominating active spectrum and an underlying passive emission spectrum. Its analysis requires modelling of both active and passive features. Examples used here are from the CXRS diagnostic at JET and TEXTOR. They display characteristic features of the main light impurity ions (C{sup +6}, He{sup +2}, N

  11. Reactor Neutrino Spectra

    CERN Document Server

    Hayes, A C

    2016-01-01

    We present a review of the antineutrino spectra emitted from reactors. Knowledge of these and their associated uncertainties are crucial for neutrino oscillation studies. The spectra used to-date have been determined by either conversion of measured electron spectra to antineutrino spectra or by summing over all of the thousands of transitions that makeup the spectra using modern databases as input. The uncertainties in the subdominant corrections to beta-decay plague both methods, and we provide estimates of these uncertainties. Improving on current knowledge of the antineutrino spectra from reactors will require new experiments. Such experiments would also address the so-called reactor neutrino anomaly and the possible origin of the shoulder observed in the antineutrino spectra measured in recent high-statistics reactor neutrino experiments.

  12. 多波段相关光子光谱分布与时间相关性测量实验研究%Research on the Distribution of Broad-Band Correlated Photon Spectra and the Measurement of Time-Correlation

    Institute of Scientific and Technical Information of China (English)

    高冬阳; 李健军; 夏茂鹏; 郑小兵

    2016-01-01

    基于相关光子的定标技术能够实现“无标准传递”绝对定标,研究相关光子的光谱辐射特性及时间相关特性对遥感器在宽波段的辐射定标具有重要意义。为满足光电探测器在宽谱段量子效率定标需求,基于相关光子的定标技术有必要从单一波段向更多波段扩展。根据自发参量下转换所满足的相位匹配条件,推导出相关光子在晶体内的非共线角计算公式,通过数值模拟相关光子光谱辐射角度分布规律,优化晶体相位匹配角,使得自发参量下转换产生的相关光子具有宽光谱分布,并且相关光子辐射角度与光谱波长能够一一对应。根据光谱分布数值模拟结果,建立了多波段相关光子的光谱分布和时间相关性测量实验系统,利用该系统测量了四对相关光子的光谱分布、符合计数、相关时间以及偏振特性。其中,测量的光谱分布范围为633~808 nm,最大光谱分布测量偏差为1.51 mm,光谱分布实验测量结果与数值模拟结果符合一致;测量了四对相关光子对的相关时间,最小相关时间为0.32 ns,并在实验中观察到了“符合三峰”现象;相关光子单光子计数及符合计数与泵浦光的偏振方向呈正弦函数关系。实验研究表明,相关光子对具有可见光~近红外宽波段分布、时间相关及偏振特性。论文研究结果在国内外尚属首次报道,该研究结果有望应用于光电探测器在多波段的辐射定标。%The correlated photon technique makes it possible to achieve a radiation calibration processing without chain transfer-ring.The study of the spectral radiation character and time correlation of the photon is of great significance for broad-band radio-metric calibration.To absolutely calibrate quantum efficiency of photoelectric detector,it is necessary to extend calibration band from single band to more bands.According to the phase-matching condition of the spontaneous

  13. Perspective: The first ten years of broadband chirped pulse Fourier transform microwave spectroscopy.

    Science.gov (United States)

    Park, G Barratt; Field, Robert W

    2016-05-28

    Since its invention in 2006, the broadband chirped pulse Fourier transform spectrometer has transformed the field of microwave spectroscopy. The technique enables the collection of a ≥10 GHz bandwidth spectrum in a single shot of the spectrometer, which allows broadband, high-resolution microwave spectra to be acquired several orders of magnitude faster than what was previously possible. We discuss the advantages and challenges associated with the technique and look back on the first ten years of chirped pulse Fourier transform spectroscopy. In addition to enabling faster-than-ever structure determination of increasingly complex species, the technique has given rise to an assortment of entirely new classes of experiments, ranging from chiral sensing by three-wave mixing to microwave detection of multichannel reaction kinetics. However, this is only the beginning. Future generations of microwave experiments will make increasingly creative use of frequency-agile pulse sequences for the coherent manipulation and interrogation of molecular dynamics.

  14. Signatures of Accretion Shocks in Broadband Spectrum of Advective Flows Around Black Holes

    CERN Document Server

    Mandal, S; Mandal, Samir; Chakrabarti, Sandip K.

    2005-01-01

    We compute the effects of the centrifugal pressure supported shock waves on the emitted spectrum from an accretion disk primarily consisting of low angular momentum matter. Electrons are very efficiently accelerated by the accretion shock and acquire power-law distribution. The accelerated particles in turn emit synchrotron radiation in presence of a stochastic magnetic field in equipartition with the gas. Efficient cooling of the electrons by these soft photons reduces its temperature in comparison to the protons. We explore the nature of the broadband spectra by using Comptonization, bremsstrahlung and synchrotron emission. We then show that there could be two crossing points in a broadband spectrum, one near $\\sim 10 keV$ and the other $\\sim 300-400$KeV.

  15. Perspective: The first ten years of broadband chirped pulse Fourier transform microwave spectroscopy

    Science.gov (United States)

    Park, G. Barratt; Field, Robert W.

    2016-05-01

    Since its invention in 2006, the broadband chirped pulse Fourier transform spectrometer has transformed the field of microwave spectroscopy. The technique enables the collection of a ≥10 GHz bandwidth spectrum in a single shot of the spectrometer, which allows broadband, high-resolution microwave spectra to be acquired several orders of magnitude faster than what was previously possible. We discuss the advantages and challenges associated with the technique and look back on the first ten years of chirped pulse Fourier transform spectroscopy. In addition to enabling faster-than-ever structure determination of increasingly complex species, the technique has given rise to an assortment of entirely new classes of experiments, ranging from chiral sensing by three-wave mixing to microwave detection of multichannel reaction kinetics. However, this is only the beginning. Future generations of microwave experiments will make increasingly creative use of frequency-agile pulse sequences for the coherent manipulation and interrogation of molecular dynamics.

  16. Model of a black hole gas submitted to background gravitational field for active galaxy nuclei with application to calculating the continuous emission spectra of massless particles (Photons: neutrinos and gravitons)

    International Nuclear Information System (INIS)

    A new theoretical model for active galaxy nuclei which describes the continuous spectrum of rest massless particles (photons, neutrinos and gravitons) in the frequency range from radiofrequency to gamma ray frequency, is presented. The model consists in a black hole gas interacting with a background gravitacional field. The previously models proposed for active galaxy nuclei are exposured. Whole theoretical fundaments based on Einstein general relativity theory for defining and studying singularity properties (black holes) are also presented. (M.C.K.)

  17. Experimental characterization of broadband electrostatic noise due to plasma compression

    Science.gov (United States)

    Dubois, Ami M.; Thomas, Edward, Jr.; Amatucci, William E.; Ganguli, Gurudas

    2015-11-01

    For a wide variety of laboratory and space plasma environments, theory states that plasmas are unstable to transverse shear flows over a very broad frequency range, where the shear scale length (LE) compared to the ion gyro-radius (ρi) determines the character of the shear-driven instability that may prevail. During active periods in the Earth's magnetosphere, such sheared flows are intensified and broadband electrostatic noise (BEN) is often observed by satellites traversing natural boundary layers. An interpenetrating magnetized plasma configuration is used to create a transverse velocity shear profile similar to that found at natural space plasma boundary layers. The continuous variation and the associated transition of the instability regimes driven by the shear flow mechanism are demonstrated in a single laboratory experiment. For the first time, broadband wave emission, which is correlated to increasing/decreasing stress (i.e., ρi/LE) on a plasma boundary layer, is found under controlled and repeatable conditions. This result provides evidence that the compression/relaxation of a plasma boundary layer leads to a BEN signature and holds out the promise for understanding the cause and effect of the in situ observation of BEN by satellites. This project was supported with funding from the U.S. Department of Energy, the Defense Threat Reduction Agency, and NRL Base Funds.

  18. A highly innovative global broadband mobile communication system concept

    Science.gov (United States)

    Wittig, Manfred

    2010-04-01

    Global mobile communication systems deployed in the 1990s (Iridium and Globalstar) failed to achieve the expected market success. However, recently a second generation of these two LEO constellations have been or will be procured. This shows evidence that global mobile satellite communications are attractive for a certain class of users. Basic requirements for mobile satellite communication networks are global coverage at high elevation angles, continuous availability and most important attractive service offers. For the first two reasons LEO constellations were designed and deployed. The large number of required satellites (remember the original Teledesic concept was designed containing 860 satellites) increases the CAPEX and consequently the service cost. This is probably the major reason for the limited commercial success of Iridium and Globalstar. An ideal global mobile (broadband) communication system shall provide global coverage at high elevation angles (not below e.g. 30°) with the lowest number of satellites. This seems to be contradictory. However, a solution will be presented that achieves global coverage which requires only five satellites and achieves high elevation angles even at polar locations. This orbit constellation is to be complemented with innovative payloads to achieve cost efficient broadband mobile services all over the Globe. Innovative L/S-band payload concepts will be introduced as well as Ka-band payloads.

  19. The GREGOR Broad-Band Imager

    Science.gov (United States)

    von der Lühe, O.; Volkmer, R.; Kentischer, T. J.; Geißler, R.

    2012-11-01

    The design and characteristics of the Broad-Band Imager (BBI) of GREGOR are described. BBI covers the visible spectral range with two cameras simultaneously for a large field and with critical sampling at 390 nm, and it includes a mode for observing the pupil in a Foucault configuration. Samples of first-light observations are shown.

  20. Fibre laser based broadband THz imaging systems

    DEFF Research Database (Denmark)

    Eichhorn, Finn

    State-of-the-art optical fiber technology can contribute towards complex multi-element broadband terahertz imaging systems. Classical table-top terahertz imaging systems are generally limited to a single emitter/receiver pair, which constrains their imaging capability to tedious raster scanning i...

  1. Is European Broadband Ready for Smart Grid?

    DEFF Research Database (Denmark)

    Balachandran, Kartheepan; Pedersen, Jens Myrup

    2014-01-01

    In this short paper we compare the communication requirements for three Smart Grid scenarios with the availability of broadband and mobile communication networks in Europe. We show that only in the most demanding case - where data is collected and transmitted every second - a standard GSM...

  2. Broadband optical isolator in fibre optics

    OpenAIRE

    Berent, Michal; Rangelov, Andon A.; Vitanov, Nikolay V.

    2013-01-01

    We propose a broadband optical diode, which is composed of one achromatic reciprocal quarter-wave plate and one non-reciprocal quarter-wave plate, both placed between two crossed polarizers. The presented design of achromatic wave plates relies on an adiabatic evolution of the Stokes vector, thus, the scheme is robust and efficient. The possible simple implementation using fiber optics is suggested.

  3. Localization of aerial broadband noise by pinnipeds

    Science.gov (United States)

    Holt, Marla M.; Schusterman, Ronald J.; Southall, Brandon L.; Kastak, David

    2004-05-01

    Although many pinnipeds (seals, sea lions, and walruses) emit broadband calls on land as part of their communication system, few studies have addressed these animals' ability to localize aerial broadband sounds. In this study, the aerial sound localization acuities of a female northern elephant seal (Mirounga angustirostris), a male harbor seal (Phoca vitulina), and a female California sea lion (Zalophus californianus) were measured in the horizontal plane. The stimulus was broadband white noise that was band pass filtered between 1.2 and 15 kHz. Testing was conducted in a hemi-anechoic chamber using a left/right forced choice procedure to measure the minimum audible angle (MAA) for each subject. MAAs were defined as half the angular separation of two sound sources bisected by a subject's midline that corresponded to 75% correct discrimination. MAAs were 4.7°, 3.6°, and 4.2° for the northern elephant seal, harbor seal, and California sea lion, respectively. These results demonstrate that individuals of these pinniped species have sound localization abilities comparable to the domestic cat and rhesus macaque. The acuity differences between our subjects were small and not predicted by head size. These results likely reflect the relatively acute general abilities of pinnipeds to localize aerial broadband signals.

  4. Adjustable, Broadband, Selective Excitation with Uniform Phase

    Science.gov (United States)

    Cano, Kristin E.; Smith, Mari A.; Shaka, A. J.

    2002-03-01

    An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase means that, neglecting spin-spin coupling, all resonance lines have nearly the same phase. Conventional uniform-phase excitation pulses (e.g., E-BURP), mostly based on amplitude modulation of the RF field, are not broadband: they have an achievable bandwidth that is strictly limited by the peak power available. Other compensated pulses based on adiabatic half-passage, like BIR-4, are not selective. By contrast, inversion pulses based on adiabatic fast passage can be broadband (and selective) in the sense above. The advance outlined is a way to reformulate these frequency modulated (FM) pulses for excitation, rather than just inversion.

  5. 75 FR 29516 - Broadband Researchers' Data Workshop

    Science.gov (United States)

    2010-05-26

    ... a public meeting concerning the nature of data related to broadband Internet access and use that the..., ``Innovation in the Economy: Drive Economic Growth and Solve National Problems by Deploying a 21st Century...) to provide up-to-date information on the extent of the Nation's Internet adoption and the...

  6. 75 FR 3820 - Broadband Initiatives Program

    Science.gov (United States)

    2010-01-22

    ... to provide a ``direct fiscal boost to help lift our Nation from the greatest economic crisis in our... impacted by the recession; (3) to provide investments needed to increase economic efficiency by spurring... proposed rural economic development strategies incorporating broadband technology are given...

  7. EMERGING BROADBAND WIRELESS TECHNOLOGIES: WIFI AND WIMAX

    Directory of Open Access Journals (Sweden)

    Rama K. Raju

    2012-07-01

    Full Text Available Now-a-days there is high demand for broadband mobile services. Traditional high-speed broadband solutions depend on wired technologies namely digital subscriber line (DSL. Wifi and Wimax are useful in providing any type of connectivity such as the fixed or portable or nomadic connectivity without the requirement of LoS (Line of Sight of the base station. Mobile Broadband Wireless Network (MBWN is a flexible and economical solution for remote areas where wired technology and also terminal mobility cannot be provided. The IEEE Wi-Fi and Wi-Max/802.16 are the most promising technologies for broadband wireless metropolitan area networks (WMANs and these are capable of providing high throughput even on long distances with varied QoS. These technologies ensure a wireless network that enables high speed Internet access to residential, small and medium business customers, as well as Internet access for WiFi hot spots and cellular base stations. These offer support to both point-to-multipoint (P2MP and multipoint-to-multipoint (mesh nodes and offers high speed data (voice, video service to the customers. In this paper, we study the issues related to, benefits and deployment of these technologies.

  8. FMCW Radar with Broadband Communication Capability

    NARCIS (Netherlands)

    Barrenechea, P.; Elferink, F.H.; Janssen, J.A.A.J.

    2007-01-01

    The use of amplitude modulation to encode information onto an FMCW radar signal is proposed in this paper. This new technique, that has been named AM-FMCW communicating radar, provides a new channel for broadband communication by reusing the radar frequencies and without introducing any distortion i

  9. BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER

    DEFF Research Database (Denmark)

    2010-01-01

    Broadband travelling wave semiconductor optical amplifier (100, 200, 300, 400, 800) for amplification of light, wherein the amplifier (100, 200, 300, 400, 800) comprises a waveguide region (101, 201, 301, 401, 801) for providing confinement of the light in transverse directions and adapted...

  10. Measurement and prediction of broadband noise from large horizontal axis wind turbine generators

    Science.gov (United States)

    Grosveld, F. W.; Shepherd, K. P.; Hubbard, H. H.

    1995-05-01

    A method is presented for predicting the broadband noise spectra of large wind turbine generators. It includes contributions from such noise sources as the inflow turbulence to the rotor, the interactions between the turbulent boundary layers on the blade surfaces with their trailing edges and the wake due to a blunt trailing edge. The method is partly empirical and is based on acoustic measurements of large wind turbines and airfoil models. Spectra are predicted for several large machines including the proposed MOD-5B. Measured data are presented for the MOD-2, the WTS-4, the MOD-OA, and the U.S. Windpower Inc. machines. Good agreement is shown between the predicted and measured far field noise spectra.

  11. Measurement and prediction of broadband noise from large horizontal axis wind turbine generators

    Science.gov (United States)

    Grosveld, F. W.; Shepherd, K. P.; Hubbard, H. H.

    1995-01-01

    A method is presented for predicting the broadband noise spectra of large wind turbine generators. It includes contributions from such noise sources as the inflow turbulence to the rotor, the interactions between the turbulent boundary layers on the blade surfaces with their trailing edges and the wake due to a blunt trailing edge. The method is partly empirical and is based on acoustic measurements of large wind turbines and airfoil models. Spectra are predicted for several large machines including the proposed MOD-5B. Measured data are presented for the MOD-2, the WTS-4, the MOD-OA, and the U.S. Windpower Inc. machines. Good agreement is shown between the predicted and measured far field noise spectra.

  12. Measuring sustainable broadband adoption: An innovative approach to understanding broadband adoption and use

    OpenAIRE

    Larose, Robert; De Maagd, Kurt; Chew, Han Ei; Tsai, Hsin-yi Sandy; Steinfield, Charles; Wildman, Steven S; Bauer, Johannes M.

    2012-01-01

    Efforts to promote sustainable broadband Internet adoption urge new attention to the classic diffusion of innovations paradigm. For this study, innovation attributes were reconceptualized following Social Cognitive Theory (SCT). In a sample of inner-city residents, the model accounted for 36% of the variance in intentions to adopt broadband technology and services, primarily from the SCT variables of expected outcomes and self-efficacy. Prior habitual use of the Internet was also a predictor....

  13. Investment in broadband infrastructure under local deregulation: Evidence from the UK broadband market

    OpenAIRE

    Fabritz, Nadine; Falck, Oliver

    2013-01-01

    This paper investigates telecommunication operator investment in broadband infrastructure after local deregulation of the wholesale broadband access market. Using a panel dataset covering all 5,598 exchange areas in the United Kingdom, we exploit regional differences in deregulation following a 2008 reform. Controlling for initial conditions, first-difference estimates show that local deregulation increases local investment in infrastructure by both the incumbent and competitors.

  14. Validation of Broadband Ground Motion Simulations for Japanese Crustal Earthquakes by the Recipe

    Science.gov (United States)

    Iwaki, A.; Maeda, T.; Morikawa, N.; Miyake, H.; Fujiwara, H.

    2015-12-01

    The Headquarters for Earthquake Research Promotion (HERP) of Japan has organized the broadband ground motion simulation method into a standard procedure called the "recipe" (HERP, 2009). In the recipe, the source rupture is represented by the characterized source model (Irikura and Miyake, 2011). The broadband ground motion time histories are computed by a hybrid approach: the 3-D finite-difference method (Aoi et al. 2004) and the stochastic Green's function method (Dan and Sato, 1998; Dan et al. 2000) for the long- (> 1 s) and short-period (structure model. As the engineering significance of scenario earthquake ground motion prediction is increasing, thorough verification and validation are required for the simulation methods. This study presents the self-validation of the recipe for two MW6.6 crustal events in Japan, the 2000 Tottori and 2004 Chuetsu (Niigata) earthquakes. We first compare the simulated velocity time series with the observation. Main features of the velocity waveforms, such as the near-fault pulses and the large later phases on deep sediment sites are well reproduced by the simulations. Then we evaluate 5% damped pseudo acceleration spectra (PSA) in the framework of the SCEC Broadband Platform (BBP) validation (Dreger et al. 2015). The validation results are generally acceptable in the period range 0.1 - 10 s, whereas those in the shortest period range (0.01-0.1 s) are less satisfactory. We also evaluate the simulations with the 1-D velocity structure models used in the SCEC BBP validation exercise. Although the goodness-of-fit parameters for PSA do not significantly differ from those for the 3-D velocity structure model, noticeable differences in velocity waveforms are observed. Our results suggest the importance of 1) well-constrained 3-D velocity structure model for broadband ground motion simulations and 2) evaluation of time series of ground motion as well as response spectra.

  15. Teledesic broadband center field study

    OpenAIRE

    Webster, Tom P.E.; Bannon, Rachel; Lehrer, David AIA

    2002-01-01

    The design of many unconventional internet and technology office spaces in the late 90’s has challenged many standard conventions of workplace protocol. Although it is easy to poke fun at the free café lattes, foosball machines, and dogs in the office, the desire to create a workplace that is healthier, more functional, and casual is seen by many as a positive and continuing trend. The question then arises, how well do these new innovative workplaces actually perform? The Teledesic B...

  16. Management of broadband technology and innovation policy, deployment, and use

    CERN Document Server

    Choudrie, Jyoti

    2013-01-01

    When one considers broadband, the Internet immediately springs to mind. However, broadband is impacting society in many ways. For instance, broadband networks can be used to deliver healthcare or community related services to individuals who don't have computers, have distance as an issue to contend with, or don't use the internet. Broadband can support better management of scarce energy resources with the advent of smart grids, enables improved teleworking capacity and opens up a world of new entertainment possibilities. Yet scholarly examinations of broadband technology have so far examin

  17. Broadband passive optical network media access control protocols

    Science.gov (United States)

    Quayle, Alan

    1996-11-01

    Most telecommunication operators are currently deciding on how to respond to customers' needs stimulated by the synergy between compression coding of multimedia and the emergence of broadband digital networks. This paper describes a range of broadband access architectures under consideration in the full services access network initiative. All architectures have a common requirement for a broadband ATM PON. A common broadband PON applicable to many operators increases the world-wide market for the product. With greater production volumes manufacturers' costs reduce because of the experience curve effect making broadband access systems economic.

  18. Development of dual-broadband rotational CARS for combustion diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Bood, Joakim

    2000-06-01

    The present thesis concerns development and application of dual-broadband rotational coherent anti-Stokes Raman spectroscopy (DB-RCARS) for temperature and species concentration measurements in combustion processes. Both fundamental development of the technique, including experimental as well as modelling results, and measurements in practical combustion devices were conducted. A code for calculation of rotational CARS spectra of pure acetylene as well as mixtures of acetylene and nitrogen was developed. Using this code, temperatures and relative acetylene to nitrogen concentrations were evaluated from DB-RCARS measurements in pure acetylene and different acetylene/nitrogen mixtures. Moreover, rotational CARS spectra of dimethyl-ether (DME) have been analyzed. A powerful tool for simultaneous temperature and multiple species concentration measurements was developed by combining rotational CARS with vibrational CARS. The concept was demonstrated for measurements of temperature, oxygen, and carbon monoxide concentrations simultaneously in a premixed sooting ethene/air flame. Rotational CARS spectra of nitrogen at very high pressures (0.1-44 MPa) at room temperature were investigated. The experimental spectra were compared with calculated spectra using different Raman linewidth models. The results indicate some shortcomings in the present model, basically the density calculation and neglecting overlapping effects between adjacent spectral lines. A new method for CARS measurements in several spatially separated points simultaneously was developed. By using DB-RCARS the method was demonstrated for quantitative measurements of profiles of temperatures and oxygen concentrations. An atomic filter for rejection of stray light was developed. The filter was shown to efficiently reject stray light from the narrowband laser without affecting the shape of the rotational CARS spectrum or causing any signal losses. Within an interdisciplinary project intended to increase the

  19. Skyshine spectra of gamma rays

    International Nuclear Information System (INIS)

    A study of the spectra of gamma photons back-scattered in vertical direction by infinite air above ground (skyshine) is presented. The source for these measurements is a 650 Ci Cobalt-60 point-source and the skyshine spectra are reported for distances from 150 m to 325 m from the source, measured with a 5 cm x 5 cm NaI(Tl) detector collimated with collimators of 12 mm and 20 mm diameter and 5 cm length. These continuous spectra are unfolded with Gold's iterative technique. The photon-spectra so obtained have a distinct line at 72 keV due to multiply-scattered photons. This is an energy where photoelectric and Compton cross-sections for multiply-scattered photons balance each other. The intensity of the line(I) decreases exponentially with distance (d) from the source obeying a relation of the type I = Isub(o)esup(-μd) where μ is called as ''Multiply-Scatter Coefficient'', a constant of the medium which is air in these measurements. This relationship is explained in terms of a halo around the source comprising of multiply-scattered gamma photons, Isub(0) being the intensity of these scattered photons at the location of cobalt-source. A fraction called as ''Back-scattered Fraction'', the ratio of Isub(0) to the number of original photons from the cobalt-source entering the infinite air, is also calculated. It is shown that with a properly calibrated detector system, this fraction can be used to determine the strength of a large gamma source, viz. a nuclear explosion in air, and for mineral prospecting. These conclusions are general and can be applied to any other infinite medium. Some forward-scatter (transmission) spectra of cobalt-60 source through 10 cm of Pb and 2.5 cm of Al are also reported. (auth.)

  20. Local government broadband policies for areas with limited Internet access

    Directory of Open Access Journals (Sweden)

    Yoshio Arai

    2014-03-01

    Full Text Available Despite their wide diffusion in developed countries, broadband services are still limited in areas where providing them is not profitable for private telecom carriers. To address this, many local governments in Japan have implemented broadband deployment projects subsidized by the national government. In this paper, we discuss local government broadband policies based on survey data collected from municipalities throughout the country. With the support of national promotion policies, broadband services were rapidly introduced to most local municipalities in Japan during the 2000s. Local government deployment policies helped to reduce the number of areas with no broadband access. A business model based on the Indefeasible Right of Use (IRU contract between a private telecom carrier and a local government has been developed in recent years. Even local governments without the technical capacity to operate a broadband business can introduce broadband services into their territory using the IRU business model.

  1. Spectra of alkali atoms

    International Nuclear Information System (INIS)

    Emission spectra of alkali atoms has been determined by using spectrometer at the ultraviolet to infra red waves range. The spectra emission can be obtained by absorption spectrophotometric analysis. Comparative evaluations between experimental data and data handbook obtained by spark method were also presented. (author tr.)

  2. Best-basis analysis of broadband tremor signals

    Directory of Open Access Journals (Sweden)

    P. Steffen

    1999-06-01

    Full Text Available Active volcanoes usually generate highly non-stationary broadband tremor signals. Short-time shock events with a frequency content of several decades are superimposed on a stationary narrow band continuous tremor. Tremor signals of this type can be observed in the near field of many active volcanoes. In this paper we will demonstrate the analysis of such signals using a specific tremor signal of Mt. Stromboli (Sicily. We used the Best-Basis Algorithm (BBA in order to compute a spectrogram which is adapted to signal properties on highly different scales. It turns out that the BBA can reveal better fitting properties of the tremor in the time-frequency plane compared to standard methods like Short-Time Fourier Transformation (STFT. Moreover, this very effective algorithm can be used for real time monitoring in the time-frequency plane, for data compression or for de-noising of the tremor signals.

  3. Broadband RF front-end using microwave photonics filter.

    Science.gov (United States)

    Wang, Jingjing; Chen, Minghua; Liang, Yunhua; Chen, Hongwei; Yang, Sigang; Xie, Shizhong

    2015-01-26

    We propose and demonstrate a novel RF front-end with broadened processing bandwidth, where a tunable microwave photonic filter based on optical frequency comb (OFC) is incorporated to accomplish simultaneous down-conversion and filtering. By designing additional phase shaping and time delay controlling, the frequency tunability of the system could be enhanced. More importantly, the beating interferences generated from broadband RF input could also be suppressed, which help to break the limitation on the processing bandwidth. In our experiments, a photonics RF receiver front-end for RF input with wide bandwidth of almost 20 GHz was realized using 10-GHz-space OFC, where the center frequency of the pass band signals could be tuned continuously. PMID:25835844

  4. High frequency fall-off of source spectra using Q-free spectra estimation

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A broadband seismogram may be represented by a convolution of source time function, the propagation operator and the scattering/attenuation operator. As the propagation operator is frequency-independent, and the scattering/attenuation effect may be described by a Q-factor depending on frequency via Q-1=Q-11+(Q2ω)-1, considering a combination of the displacement spectra, the source spectra may directly be estimated, in which the contribution of the Q-value may be eliminated automatically. Using this algorithm, the near-source broadband seismograms of five aftershocks of the 1988 Lancang-Gengma, Yunnan Province, China earthquake were processed. The results for the ML=3.0 and ML=3.5 aftershocks show that for the same earthquake, similar high-frequency fall-off may be obtained from different recording stations. The result for the MS=6.7 aftershock shows that consistent source parameters may be gotten from different seismic stations. The parameters estimated also agree with the results obtained by empirical Green's function approach. The high-frequency spectra of the aftershocks exhibit a typical f-γ fall-off. For the ML=3.0 aftershock,γ≈3 ; for the MS=6.7 and ML=4.0 aftershocks,γ≈2; and for the ML=3.5 and ML=3.0 aftershocks, γ≈2.5. The corner frequency of the MS=6.7 aftershock indicates that it has a small source dimension, implying that it may come from the rupture of a small but strong barrier.

  5. A broadband cavity ringdown spectrometer for in-situ measurements of atmospheric trace gases

    Directory of Open Access Journals (Sweden)

    M. Bitter

    2005-01-01

    Full Text Available This paper describes a broadband cavity ringdown spectrometer and its deployment during the 2002 North Atlantic Marine Boundary Layer Experiment (NAMBLEX to measure ambient concentrations of NO3, N2O5, I2 and OIO at the Mace Head Atmospheric Research Station, Co. Galway, Ireland. The effective absorption path lengths accessible with the spectrometer generally exceeded 10 km, enabling sensitive localised ``point' measurements of atmospheric absorbers to be made adjacent to the other instruments monitoring chemically related species at the same site. For the majority of observations, the spectrometer was used in an open path configuration thereby avoiding surface losses of reactive species. A subset of observations targeted the N2O5 molecule by detecting the additional NO3 formed by the thermal dissociation of N2O5. In all cases the concentrations of the atmospheric absorbers were retrieved by fitting the differential structure in the broadband cavity ringdown spectra using a methodology adapted from long path differential optical absorption spectroscopy. The uncertainty of the retrieval depends crucially on the correct treatment and fitting of the absorption bands due to water vapour, a topic that is discussed in the context of analysing broadband cavity ringdown spectra. The quality of the measurements and the retrieval method are illustrated with representative spectra acquired during NAMBLEX in spectral regions around 660 nm (NO3 and N2O5 and 570 nm (I2 and OIO. Typical detection limits were 1 pptv for NO3 in an integration time of 100 s, 4 pptv for OIO and 20 pptv for I2 in an integration time of 10 min. Additionally, the concentrations of atmospheric water vapour and the aerosol optical extinction were retrieved in both spectral regions. A companion paper in this issue presents the time series of the measurements and discusses their significance for understanding the variability of short lived nitrogen and iodine compounds in the marine

  6. Techno-Economics of Residential Broadband Deployment

    DEFF Research Database (Denmark)

    Sigurdsson, Halldor Matthias

    2007-01-01

    broadband deployment strategy is depending on a complexed set of parameters, and there is a demand for precise techno-economic cost models estimating financial feasibility. The existing cost models do not consider the dynamic developments in the market caused by competition. The PhD thesis has a profound...... regulation theory. Based upon this a techno-economic cost model is made that simulates capital expenses and services. As a special element of the model game theory is used to simulate the interaction between competitive infrastructures. The work has a specific focus on the Danish market. It follows......PhD-projektet har titlen ”Techno-Economics of residential broadband deployment” (”Tekno-økonomisk analyse af bredbåndsforbindelser til private husstande”). Det omhandler den aktuelle markedssituation for bredbåndstjenester, hvor elselskaberne udfordrer de traditionelle teleselskaber ved massiv...

  7. A Broadband Dipolar Resonance in THz Metamaterials

    CERN Document Server

    Sangala, Bagvanth Reddy; Gopal, Achanta Venu; Prabhu, S S

    2014-01-01

    We demonstrate a THz metamaterial with broadband dipole resonance originating due to the hybridization of LC resonances. The structure optimized by finite element method simulations is fabricated by electron beam lithography and characterized by terahertz time-domain spectroscopy. Numerically, we found that when two LC metamaterial resonators are brought together, an electric dipole resonance arises in addition to the LC resonances. We observed a strong dependence of the width of these resonances on the separation between the resonators. This dependence can be explained based on series and parallel RLC circuit analogies. The broadband dipole resonance appears when both the resonators are fused together. The metamaterial has a stopband with FWHM of 0.47 THz centered at 1.12 THz. The experimentally measured band features are in reasonable agreement with the simulated ones. The experimental power extinction ratio of THz in the stopbands is found to be 15 dB.

  8. Random Lasers for Broadband Directional Emission

    CERN Document Server

    Schönhuber, Sebastian; Hisch, Thomas; Deutsch, Christoph; Krall, Michael; Detz, Hermann; Strasser, Gottfried; Rotter, Stefan; Unterrainer, Karl

    2016-01-01

    Broadband coherent light sources are becoming increasingly important for sensing and spectroscopic applications, especially in the mid-infrared and terahertz (THz) spectral regions, where the unique absorption characteristics of a whole host of molecules are located. The desire to miniaturize such light emitters has recently lead to spectacular advances with compact on-chip lasers that cover both of these spectral regions. The long wavelength and the small size of the sources result in a strongly diverging laser beam that is difficult to focus on the target that one aims to perform spectroscopy with. Here, we introduce an unconventional solution to this vexing problem relying on a random laser to produce coherent broadband THz radiation as well as an almost diffraction limited far-field emission profile. Our random lasers do not require any fine-tuning and thus constitute a promising example of practical device applications for random lasing.

  9. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

  10. Broad-band acoustic hyperbolic metamaterial

    CERN Document Server

    Shen, Chen; Sui, Ni; Wang, Wenqi; Cummer, Steven A; Jing, Yun

    2015-01-01

    Acoustic metamaterials (AMMs) are engineered materials, made from subwavelength structures, that exhibit useful or unusual constitutive properties. There has been intense research interest in AMMs since its first realization in 2000 by Liu et al. A number of functionalities and applications have been proposed and achieved using AMMs. Hyperbolic metamaterials are one of the most important types of metamaterials due to their extreme anisotropy and numerous possible applications, including negative refraction, backward waves, spatial filtering, and subwavelength imaging. Although the importance of acoustic hyperbolic metamaterials (AHMMs) as a tool for achieving full control of acoustic waves is substantial, the realization of a broad-band and truly hyperbolic AMM has not been reported so far. Here, we demonstrate the design and experimental characterization of a broadband AHMM that operates between 1.0 kHz and 2.5 kHz.

  11. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    Science.gov (United States)

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-08-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  12. Broadband Visible Light Induced NO Formation

    Science.gov (United States)

    Lubart, Rachel; Eichler, Maor; Friedmann, Harry; Savion, N.; Breitbart, Haim; Ankri, Rinat

    2009-06-01

    Nitric oxide formation is a potential mechanism for photobiomodulation because it is synthesized in cells by nitric oxide synthase (NOS), which contains both flavin and heme, and thus absorbs visible light. The purpose of this work was to study broadband visible light induced NO formation in various cells. Cardiac, endothelial, sperm cells and RAW 264.7 macrophages were illuminated with broadband visible light, 40-130 mW/cm2, 2.4-39 J/cm2, and nitric oxide production was quantified by using the Griess reagent. The results showed that visible light illumination increased NO concentration both in sperm and endothelial cells, but not in cardiac cells. Activation of RAW 264.7 macrophages was very small. It thus appears that NO is involved in photobiomodulation, though different light parameters and illumination protocols are needed to induce NO in various cells.

  13. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-08-31

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  14. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-01-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe. PMID:27578317

  15. The EarthCARE broadband radiometer detectors

    Science.gov (United States)

    Proulx, Christian; Williamson, Fraser; Allard, Martin; Baldenberger, Georges; Gay, David; Garcia-Blanco, Sonia; Côté, Patrice; Martin, Louis; Larouche, Carl; Ilias, Samir; Pope, Tim; Caldwell, Martin; Ward, Kim; Delderfield, John

    2009-08-01

    The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR instrument objective is to provide top-of-atmosphere (TOA) radiance measurements in two spectral channels, and over three along-track directions. The instrument has three fixed telescopes (one for each view) each containing a broadband detector. Each detector consists of an uncooled 30-pixel linear focal plane array (FPA) coated with gold black in order to ensure uniform spectral responsivity from 0.2 μm to 50 μm. The FPA is hybridized with a readout integrated circuit (ROIC) and a proximity electronics circuit-card assembly (CCA) packaged in an aluminum base plate with cover. This paper provides a technical description of the detector design and operation. Performance data at the FPA pixel level as well as unit-level test results on early prototypes of the detectors are also presented.

  16. Broadband Visible Light Induced NO Formation

    International Nuclear Information System (INIS)

    Nitric oxide formation is a potential mechanism for photobiomodulation because it is synthesized in cells by nitric oxide synthase (NOS), which contains both flavin and heme, and thus absorbs visible light. The purpose of this work was to study broadband visible light induced NO formation in various cells. Cardiac, endothelial, sperm cells and RAW 264.7 macrophages were illuminated with broadband visible light, 40-130 mW/cm2, 2.4-39 J/cm2, and nitric oxide production was quantified by using the Griess reagent. The results showed that visible light illumination increased NO concentration both in sperm and endothelial cells, but not in cardiac cells. Activation of RAW 264.7 macrophages was very small. It thus appears that NO is involved in photobiomodulation, though different light parameters and illumination protocols are needed to induce NO in various cells.

  17. Broadband electromagnetic response and ultrafast dynamics of few-layer epitaxial graphene

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyunyong; Borondics, Ferenc; Siegel, David A.; Zhou, Shuyun Y.; Martin, Michael C.; Lanzara, Alessandra; Kaindl, Robert A.

    2009-03-26

    We study the broadband optical conductivity and ultrafast carrier dynamics of epitaxial graphene in the few-layer limit. Equilibrium spectra of nominally buffer, monolayer, and multilayer graphene exhibit significant terahertz and near-infrared absorption, consistent with a model of intra- and interband transitions in a dense Dirac electron plasma. Non-equilibrium terahertz transmission changes after photoexcitation are shown to be dominated by excess hole carriers, with a 1.2-ps mono-exponential decay that refects the minority-carrier recombination time.

  18. Switched Broadband Services For The Home

    Science.gov (United States)

    Sawyer, Don M.

    1990-01-01

    In considering the deployment of fiber optics to the residence, two critical questions arise: what are the leading services that could be offered to justify the required investment; and what is the nature of the business that would offer these services to the consumer ? This talk will address these two questions together with the related issue of how the "financial engine" of today's television distribution infrastructure - TV advertising - would be affected by an open access system based on fiber optics coupled with broadband switching. On the business side, the talk concludes that the potential for open ended capacity expansion, fair competition between service providers, and new interactive services inherent in an open access, switched broadband system are the critical items in differentiating it from existing video and TV distribution systems. On the question of broadband services, the talk will highlight several new opportunities together with some findings from recent market research conducted by BNR. The talk will show that there are variations on existing services plus many new services that could be offered and which have real consumer appeal. The postulated open access system discussed here is visualized as having ultimately 1,000 to 2,000 video channels available to the consumer. Although this may appear to hopelessly fragment the TV audience and destroy the current TV advertising infrastructure, the technology of open access, switched broadband will present many new advertising techniques, which have the potential to be far more effective than those available today. Some of these techniques will be described in this talk.

  19. Mobility Extension for Broadband Satellite Multimedia

    OpenAIRE

    Hu, Y. Fun; Pillai, Prashant; Berioli, Matteo

    2009-01-01

    This paper presents an extension for Broadband Satellite Multimedia (BSM) to support Mobility Management (MM). To support seamless handovers, mobility related entities are proposed in the Satellite Independent Access Function (SIAF) defined over the SI-SAP interface. This enables the mapping of the mobility related primitives between the higher layer and the satellite dependant lower layers via the Satellite Dependent Access Function (SDAF). The proposed MM architecture incorporates the Media...

  20. Broadband phase-preserved optical elevator

    OpenAIRE

    Luo, Yuan; Han, Tiancheng; Zhang, Baile; Qiu, Cheng-Wei; Barbastathis, George

    2011-01-01

    Phase-preserved optical elevator is an optical device to lift up an entire plane virtually without distortion in light path or phase. Using transformation optics, we have predicted and observed the realization of such a broadband phase-preserved optical elevator, made of a natural homogeneous birefringent crystal without resorting to absorptive and narrowband metamaterials involving time-consuming nano-fabrication. In our demonstration, the optical elevator is designed to lift a sheet upwards...

  1. Broadband Waveguide QED System on a Chip

    OpenAIRE

    Quan, Qimin; Bulu, Irfan; Loncar, Marko

    2009-01-01

    We demonstrate that a slot waveguide provides a broadband loss-free platform suitable for applications in quantum optics. We find that strong coupling between light quanta and a single quantum emitter placed in the waveguide slot can be achieved with efficiency higher than 96% and Purcell factor (spontaneous emission factor) larger than 200. The proposed system is a promising platform for quantum information processing and can be used to realize an efficient single photon source and optically...

  2. Broadband high efficiency active integrated antenna

    OpenAIRE

    Qin, Yi

    2007-01-01

    Active integrated antenna (MA) is a very popular topic of research during recent decades. This is mostly due to its advantages, such as compact size, multiple functions and low cost, etc. The MA system can be regarded as an active microwave circuit which the output or input port is free space instead of a conventional 50-ohm interface. The major drawbacks of the conventional MA include narrow bandwidth, low efficiency, etc. An experimental investigation on broadband slot-coupled antenna is ca...

  3. Circularly Polarized Broadband RFID Microstrip Tag Antenna

    OpenAIRE

    B. Rajini; G. V. Subrahmanyam

    2014-01-01

    In recent years, the application of radio frequency identification (RFID) operating in the ultra-high frequency (UHF) band (860-960MHz) are expanding exponentially, due to the advantages such as long reading distance, high data transfer rate, and small tag size. So the design of a CP tag antenna with broadband characteristic is presently one of the most challenging topics. This project presents a square patch passive RFID tag antenna designed for UHF band. To a...

  4. Broadband S-band Class E HPA

    NARCIS (Netherlands)

    Wanum, M. van; Dijk, R. van; Hek, A.P. de; Vliet, F.E. van

    2009-01-01

    A broadband class E High Power Amplifier (HPA) is presented. This HPA is designed to operate at S-band (2.75 to 3.75 GHz). A power added efficiency of 50% is obtained for the two stage amplifier with an output power of 35.5 dBm on a chip area of 5.25 × 2.8 mm2.

  5. Broadband S-band class E HPA

    NARCIS (Netherlands)

    Wanum, van M.; Dijk, van R.; Hek, de A.P.; Vliet, van F.E.

    2009-01-01

    A broadband class E High Power Amplifier (HPA) is presented. This HPA is designed to operate at S-band (2.75 to 3.75 GHz). A power added efficiency of 50% is obtained for the two stage amplifier with an output power of 35.5 dBm on a chip area of 5.25 times 2.8 mm2.

  6. Broadband absorption engineering of hyperbolic metafilm patterns

    OpenAIRE

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-01-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experime...

  7. Broadband Approximations for Doubly Curved Reflector Antenna

    OpenAIRE

    V. Schejbal; J. Pidanic

    2010-01-01

    The broadband approximations for shaped-beam doubly curved reflector antennas with primary feed (rectangular horn) producing uniform amplitude and phase aperture distribution are derived and analyzed. They are very valuable for electromagnetic compatibility analyses both from electromagnetic interference and susceptibility point of view, because specialized more accurate methods such as physical optics are only used by antenna designers. To allow quick EMC analyses, typical values, beamwidth ...

  8. Rural Broadband Internet Access Supply and Demand

    OpenAIRE

    Stenberg, Peter L.; Morehart, Mitchell J.

    2009-01-01

    Internet use has grown rapidly over the last 15 years and so has its integration into the rural economy. Connecting to the Internet via high-speed technology such as DSL lines, cable, satellite, and wireless networks increases bandwidth and makes the Internet much more useful to businesses, households, and governments. Rural households are almost as likely as urban households to use the Internet. Broadband Internet access in rural areas has been less prevalent than in much more densely popula...

  9. Design of broadband single polarized antenna

    Science.gov (United States)

    Shin, Phoo Kho; Aziz, Mohamad Zoinol Abidin Abd.; Ahmad, Badrul Hisham; Ramli, Mohamad Hafize Bin; Fauzi, Noor Azamiah Md; Malek, Mohd Fareq Abd

    2015-05-01

    In practical wireless communication application, bandwidth enhancement becomes one of the major design considerations. At the same time, circular polarized (CP) antenna received much attention for the applications of modern wireless communication system when compared to linear polarized (LP) antenna. This is because CP antenna can reduce the multipath effect. Hence, broadband antenna with operating frequency at 2.4GHz for WLAN application is proposed. The proposed antenna is done by using L-probe amendment with rectangular patch. The rectangular patch and copper ground plane is separated with 10mm air gap. This approach is used to enhance the bandwidth and the gain of the proposed antenna. The bandwidth of the designed antenna is more than 200MHz which meet broadband application. The return loss for the antenna is below -10dB to achieved 90% matching efficiency. The position of L-probe feed is altered in order to obtained different polarizations. The broadband antenna had been designed and simulated by using Computer Simulation Technology (CST) software. In this paper, the comparison for single polarized antenna with the design of non-inverted patch and inverted patch is discussed. The characteristics of the S-parameter, axial ratio, gain, surface current for each designed antenna are analyzed.

  10. Pacific Array (Transportable Broadband Ocean Floor Array)

    Science.gov (United States)

    Kawakatsu, Hitoshi; Ekstrom, Goran; Evans, Rob; Forsyth, Don; Gaherty, Jim; Kennett, Brian; Montagner, Jean-Paul; Utada, Hisashi

    2016-04-01

    Based on recent developments on broadband ocean bottom seismometry, we propose a next generation large-scale array experiment in the ocean. Recent advances in ocean bottom broadband seismometry1, together with advances in the seismic analysis methodology, have enabled us to resolve the regional 1-D structure of the entire lithosphere/asthenosphere system, including seismic anisotropy (azimuthal, and hopefully radial), with deployments of ~15 broadband ocean bottom seismometers (BBOBSs). Having ~15 BBOBSs as an array unit for a 2-year deployment, and repeating such deployments in a leap-frog way or concurrently (an array of arrays) for a decade or so would enable us to cover a large portion of the Pacific basin. Such efforts, not only by giving regional constraints on the 1-D structure beneath Pacific ocean, but also by sharing waveform data for global scale waveform tomography, would drastically increase our knowledge of how plate tectonics works on this planet, as well as how it worked for the past 150 million years. International collaborations is essential: if three countries/institutions participate this endeavor together, Pacific Array may be accomplished within five-or-so years.

  11. Numerical and experimental studies of mechanisms underlying the effect of pulsed broadband terahertz radiation on nerve cells

    Energy Technology Data Exchange (ETDEWEB)

    Duka, M V; Dvoretskaya, L N; Babelkin, N S; Khodzitskii, M K; Chivilikhin, S A; Smolyanskaya, O A [St. Petersburg National Research University of Information Technologies, Mechanics and Optics, St. Petersburg (Russian Federation)

    2014-08-31

    We have studied the mechanisms underlying the effect of pulsed broadband terahertz radiation on the growth of neurites of sensory ganglia using a comparative analysis of measured reflection spectra of ganglion neurites (in the frequency range 0.1 – 2.0 THz) and spectra obtained by numerical simulation with CST Microwave Studio. The observed changes are shown to be mainly due to pulse energy absorption in the ganglion neurites. Of particular interest are the observed single resonance frequencies related to resonance size effects, which can be used to irradiate ganglia in order to activate their growth. (laser biophotonics)

  12. Novel dynamic tuning of broadband visible metamaterial perfect absorber using graphene

    Science.gov (United States)

    Jia, Xiuli; Wang, Xiaoou; Yuan, Chengxun; Meng, Qingxin; Zhou, Zhongxiang

    2016-07-01

    We present a novel dynamic tuning of a broadband visible metamaterial absorber consisting of a multilayer-graphene-embedded nano-cross elliptical hole (MGENCEH) structure. It has multiple effects, including excitation of surface plasmon polaritons and extraordinary optical transmission in the first two metal layers. A numerical simulation shows that the MGENCEH structure can realize broadband perfect absorption (BPA) from 5.85 × 1014 to 6.5 × 1014 Hz over a wide incident angle range for transverse magnetic polarized light if the chemical potential of graphene (uc) is tuned to 1.0 eV. Furthermore, it has high broadband absorption (above 96%) from 4.6 × 1014 to 6.6 × 1014 Hz and three areas of narrowband perfect absorption around 4.65 × 1014, 5.1 × 1014, and 5.6 × 1014 Hz. The changes in the absorption spectra as a function of uc can be classically explained by simply considering plasmons as damped harmonic oscillators. This BPA is broader than the result of Zhou et al. [Opt. Express 23, A413-A418 (2015)] and is particularly desirable for various potential applications such as solar energy absorbers.

  13. Broad-band study with Suzaku of the magnetar class

    CERN Document Server

    Enoto, Teruaki; Makishima, Kazuo; Rea, Nanda; Hurley, Kevein; Shibata, Shinpei

    2010-01-01

    Broad-band (0.8-70 keV) spectra of the persistent X-ray emission from 9 magnetars were obtained with Suzaku, including 3 objects in apparent outburst. The soft X-ray component was detected from all of them, with a typical blackbody temperature of kT ~ 0.5 keV, while the hard-tail component, dominating above ~10 keV, was detected at ~1 mCrab intensity from 7 of them. Therefore, the spectrum composed of a soft emission and a hard-tail component may be considered to be a common property of magnetars, both in their active and quiescent states. Wide-band spectral analyses revealed that the hard-tail component has a 1-60 keV flux, Fh, comparable to or even higher than that carried by the 1-60 keV soft component, Fs. The hardness ratio of these objects, defined as xi=Fh/Fs, was found to be tightly anti-correlated with their characteristic age tau as xi=(3.3+/-0.3)x(tau/1 kyr)^(-0.67+/-0.04) with a correlation coefficient of -0.989, over the range from xi~10 to xi~0.1. Magnetars in outburst states were found to lie o...

  14. Broadband Passive Sonar Signal Simulation in Shallow Ocean

    Directory of Open Access Journals (Sweden)

    Baiju M. Nair

    2011-07-01

    Full Text Available The broadband plane wave model is valid only in the far-field of a point source under free-field propagating conditions. However the acoustics in ocean is characterized by multi-modal acoustic propagation due to its top-bottom limited boundary conditions. The effect of multi-modal field is to alter the source spectrum while the effect of dispersion is to modify the pulse shape. Moreover the use of a plane wave beamformer in a multi-modal field leads to a bias in the bearing estimates. These effects are highly dependant on the environment parameters and have important ramifications for target localization and classification in an ocean waveguide. We propose a more realistic simulator which essentially models these effects and therefore serves to provide test signals for first hand verification of signal processing algorithms to be developed for such scenarios. This model is to be understood as a better model than the naïve plane wave model which is entirely oblivious of even the gross features such as wave propagation in an oceanic waveguide. The channel parameter so estimated from the present simulation can be convolved with the radiated noise spectra of the source to generate the passive sonar signal.Defence Science Journal, 2011, 61(4, pp.370-376, DOI:http://dx.doi.org/10.14429/dsj.61.89

  15. Numerical study of broadband spectra caused by internal shocks in magnetized relativistic jets of blazars

    CERN Document Server

    Rueda-Becerril, Jesus M; Aloy, Miguel A; Aloy, Carmen

    2013-01-01

    The internal-shocks scenario in relativistic jets has been used to explain the variability of blazars' outflow emission. Recent simulations have shown that the magnetic field alters the dynamics of these shocks producing a whole zoo of spectral energy density patterns. However, the role played by magnetization in such high-energy emission is still not entirely understood. With the aid of \\emph{Fermi}'s second LAT AGN catalog, a comparison with observations in the $\\gamma$-ray band was performed, in order to identify the effects of the magnetic field.

  16. Broadband photon time-of-flight spectroscopy of pharmaceuticals and highly scattering plastics in the VIS and close NIR spectral ranges.

    Science.gov (United States)

    Khoptyar, Dmitry; Subash, Arman Ahamed; Johansson, Sören; Saleem, Muhammad; Sparén, Anders; Johansson, Jonas; Andersson-Engels, Stefan

    2013-09-01

    We present extended spectroscopic analysis of pharmaceutical tablets in the close near infrared spectral range performed using broadband photon time-of-flight (PTOF) absorption and scattering spectra measurements. We show that the absorption spectra can be used to perform evaluation of the chemical composition of pharmaceutical tablets without need for chemo-metric calibration. The spectroscopic analysis was performed using an advanced PTOF spectrometer operating in the 650 to 1400 nm spectral range. By employing temporal stabilization of the system we achieve the high precision of 0.5% required to evaluate the concentration of tablet ingredients. In order to further illustrate the performance of the system, we present the first ever reported broadband evaluation of absorption and scattering spectra from pure and doped Spectralon®.

  17. Broadband Fan Noise Prediction System for Turbofan Engines. Volume 1; Setup_BFaNS User's Manual and Developer's Guide

    Science.gov (United States)

    Morin, Bruce L.

    2010-01-01

    Pratt & Whitney has developed a Broadband Fan Noise Prediction System (BFaNS) for turbofan engines. This system computes the noise generated by turbulence impinging on the leading edges of the fan and fan exit guide vane, and noise generated by boundary-layer turbulence passing over the fan trailing edge. BFaNS has been validated on three fan rigs that were tested during the NASA Advanced Subsonic Technology Program (AST). The predicted noise spectra agreed well with measured data. The predicted effects of fan speed, vane count, and vane sweep also agreed well with measurements. The noise prediction system consists of two computer programs: Setup_BFaNS and BFaNS. Setup_BFaNS converts user-specified geometry and flow-field information into a BFaNS input file. From this input file, BFaNS computes the inlet and aft broadband sound power spectra generated by the fan and FEGV. The output file from BFaNS contains the inlet, aft and total sound power spectra from each noise source. This report is the first volume of a three-volume set documenting the Broadband Fan Noise Prediction System: Volume 1: Setup_BFaNS User s Manual and Developer s Guide; Volume 2: BFaNS User's Manual and Developer s Guide; and Volume 3: Validation and Test Cases. The present volume begins with an overview of the Broadband Fan Noise Prediction System, followed by step-by-step instructions for installing and running Setup_BFaNS. It concludes with technical documentation of the Setup_BFaNS computer program.

  18. Broadband Fan Noise Prediction System for Turbofan Engines. Volume 2; BFaNS User's Manual and Developer's Guide

    Science.gov (United States)

    Morin, Bruce L.

    2010-01-01

    Pratt & Whitney has developed a Broadband Fan Noise Prediction System (BFaNS) for turbofan engines. This system computes the noise generated by turbulence impinging on the leading edges of the fan and fan exit guide vane, and noise generated by boundary-layer turbulence passing over the fan trailing edge. BFaNS has been validated on three fan rigs that were tested during the NASA Advanced Subsonic Technology Program (AST). The predicted noise spectra agreed well with measured data. The predicted effects of fan speed, vane count, and vane sweep also agreed well with measurements. The noise prediction system consists of two computer programs: Setup_BFaNS and BFaNS. Setup_BFaNS converts user-specified geometry and flow-field information into a BFaNS input file. From this input file, BFaNS computes the inlet and aft broadband sound power spectra generated by the fan and FEGV. The output file from BFaNS contains the inlet, aft and total sound power spectra from each noise source. This report is the second volume of a three-volume set documenting the Broadband Fan Noise Prediction System: Volume 1: Setup_BFaNS User s Manual and Developer s Guide; Volume 2: BFaNS User s Manual and Developer s Guide; and Volume 3: Validation and Test Cases. The present volume begins with an overview of the Broadband Fan Noise Prediction System, followed by step-by-step instructions for installing and running BFaNS. It concludes with technical documentation of the BFaNS computer program.

  19. Broadband near total light absorption in non-PT-symmetric waveguide-cavity systems.

    Science.gov (United States)

    Huang, Yin; Min, Changjun; Veronis, Georgios

    2016-09-19

    We introduce broadband waveguide absorbers with near unity absorption. More specifically, we propose a compact non-parity-time-symmetric perfect absorber unit cell, consisting of two metal-dielectric-metal (MDM) stub resonators with unbalanced gain and loss side-coupled to a MDM waveguide, based on unidirectional reflectionlessness at exceptional points. With proper design, light can transport through the perfect absorber unit cell with reflection close to zero in a broad wavelength range. By cascading multiple unit cell structures, the overall absorption spectra are essentially the superposition of the absorption spectra of the individual perfect absorber unit cells, and absorption of ~ 100% is supported in a wide range of frequencies. PMID:27661956

  20. Ultra-broadband infrared pump-probe spectroscopy using synchrotron radiation and a tuneable pump

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Lee; Friedli, Peter; Stutz, Stefan; Sigg, Hans [Laboratory for Micro and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Lerch, Philippe; Schneider, Joerg; Treyer, Daniel; Hunziker, Stephan [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2011-06-15

    Synchrotron infrared sources have become popular mainly because of their excellent broadband brilliance, which enables spectroscopically resolved spatial-mapping of stationary objects at the diffraction limit. In this article we focus on an often-neglected further advantage of such sources - their unique time-structure - to bring such broadband spectroscopy to the time domain, for studying dynamic phenomenon down to the 100 ps limit. We describe the ultra-broadband (12.5 to 1.1 {mu}m) Fourier transform pump-probe setup, for condensed matter transmission- and reflection-spectroscopy, installed at the X01DC infrared beam-line of the Swiss Light Source (SLS). The optical pump consists of a widely tuneable 100 ps 1 kHz laser system, covering 94% of the 16 to 1.1 {mu}m range. A thorough description of the system is given, including (i) the vector-modulator providing purely electronic tuning of the pump-probe overlap up to 1 ms with sub-ps time resolution, (ii) the 500 MHz data acquisition system interfaced with the experimental physics and industrial control system (EPICS) based SLS control system for consecutive pulse sampling, and (iii) the step-scan time-slice Fourier transform scheme for simultaneous recording of the dual-channel pumped, un-pumped, and difference spectra. The typical signal/noise ratio of a single interferogram in a 100 ps time slice is 300 (measured during one single 140 s TopUp period). This signal/noise ratio is comparable to that of existing gated Globar pump-probe Fourier transform spectroscopy, but brings up to four orders of magnitude better time resolution. To showcase the utility of broadband pump-probe spectroscopy, we investigate a Ge-on-Si material system similar to that in which optically pumped direct-gap lasing was recently reported. We show that the mid-infrared reflection-spectra can be used to determine the optically injected carrier density, while the mid- and near-infrared transmission-spectra can be used to separate the strong

  1. Ultra-broadband infrared pump-probe spectroscopy using synchrotron radiation and a tuneable pump.

    Science.gov (United States)

    Carroll, Lee; Friedli, Peter; Lerch, Philippe; Schneider, Jörg; Treyer, Daniel; Hunziker, Stephan; Stutz, Stefan; Sigg, Hans

    2011-06-01

    Synchrotron infrared sources have become popular mainly because of their excellent broadband brilliance, which enables spectroscopically resolved spatial-mapping of stationary objects at the diffraction limit. In this article we focus on an often-neglected further advantage of such sources - their unique time-structure - to bring such broadband spectroscopy to the time domain, for studying dynamic phenomenon down to the 100 ps limit. We describe the ultra-broadband (12.5 to 1.1 μm) Fourier transform pump-probe setup, for condensed matter transmission- and reflection-spectroscopy, installed at the X01DC infrared beam-line of the Swiss Light Source (SLS). The optical pump consists of a widely tuneable 100 ps 1 kHz laser system, covering 94% of the 16 to 1.1 μm range. A thorough description of the system is given, including (i) the vector-modulator providing purely electronic tuning of the pump-probe overlap up to 1 ms with sub-ps time resolution, (ii) the 500 MHz data acquisition system interfaced with the experimental physics and industrial control system (EPICS) based SLS control system for consecutive pulse sampling, and (iii) the step-scan time-slice Fourier transform scheme for simultaneous recording of the dual-channel pumped, un-pumped, and difference spectra. The typical signal/noise ratio of a single interferogram in a 100 ps time slice is 300 (measured during one single 140 s TopUp period). This signal/noise ratio is comparable to that of existing gated Globar pump-probe Fourier transform spectroscopy, but brings up to four orders of magnitude better time resolution. To showcase the utility of broadband pump-probe spectroscopy, we investigate a Ge-on-Si material system similar to that in which optically pumped direct-gap lasing was recently reported. We show that the mid-infrared reflection-spectra can be used to determine the optically injected carrier density, while the mid- and near-infrared transmission-spectra can be used to separate the strong pump

  2. Effects of polarization mode dispersion on polarization-entangled photons generated via broadband pumped spontaneous parametric down-conversion

    Science.gov (United States)

    Lim, Hyang-Tag; Hong, Kang-Hee; Kim, Yoon-Ho

    2016-05-01

    An inexpensive and compact frequency multi-mode diode laser enables a compact two-photon polarization entanglement source via the continuous wave broadband pumped spontaneous parametric down-conversion (SPDC) process. Entanglement degradation caused by polarization mode dispersion (PMD) is one of the critical issues in optical fiber-based polarization entanglement distribution. We theoretically and experimentally investigate how the initial entanglement is degraded when the two-photon polarization entangled state undergoes PMD. We report an effect of PMD unique to broadband pumped SPDC, equally applicable to pulsed pumping as well as cw broadband pumping, which is that the amount of the entanglement degradation is asymmetrical to the PMD introduced to each quantum channel. We believe that our results have important applications in long-distance distribution of polarization entanglement via optical fiber channels.

  3. Optimal multisine excitation design for broadband electrical impedance spectroscopy

    International Nuclear Information System (INIS)

    Electrical impedance spectroscopy (EIS) can be used to characterize biological materials in applications ranging from cell culture to body composition, including tissue and organ state. The emergence of cell therapy and tissue engineering opens up a new and promising field of application. While in most cases classical measurement techniques based on a frequency sweep can be used, EIS based on broadband excitations enables dynamic biological systems to be characterized when the measuring time and injected energy are a constraint. Myocardial regeneration, cell characterization in micro-fluidic systems and dynamic electrical impedance tomography are all examples of such applications. The weakness of such types of fast EIS measuring techniques resides in their intrinsic loss of accuracy. However, since most of the practical applications have no restriction over the excitation used, the input power spectrum can be appropriately designed to maximize the accuracy obtained from the measurements. This paper deals with the problem of designing the optimal multisine excitation for electrical bioimpedance measurements. The optimal multisine is obtained by the minimization of the Cramer–Rao lower bound, or what is the same, by maximizing the accuracy obtained from the measurements. Furthermore, because no analytical solution exists for global optimization involving time and frequency domains jointly, this paper presents the multisine optimization approach partially in both domains and then combines the results. As regards the frequency domain approach, a novel contribution is made for the multisine amplitude power spectrum. In the time domain, multisine is optimized by reducing its crest factor. Moreover, the impact on the information and accuracy of the impedance spectrum obtained from using different multisine amplitude power spectra is discussed, as well as the number of frequencies and frequency distributions. The theory is supported by a set of validation measurements

  4. Optimal multisine excitation design for broadband electrical impedance spectroscopy

    Science.gov (United States)

    Sanchez, B.; Vandersteen, G.; Bragos, R.; Schoukens, J.

    2011-11-01

    Electrical impedance spectroscopy (EIS) can be used to characterize biological materials in applications ranging from cell culture to body composition, including tissue and organ state. The emergence of cell therapy and tissue engineering opens up a new and promising field of application. While in most cases classical measurement techniques based on a frequency sweep can be used, EIS based on broadband excitations enables dynamic biological systems to be characterized when the measuring time and injected energy are a constraint. Myocardial regeneration, cell characterization in micro-fluidic systems and dynamic electrical impedance tomography are all examples of such applications. The weakness of such types of fast EIS measuring techniques resides in their intrinsic loss of accuracy. However, since most of the practical applications have no restriction over the excitation used, the input power spectrum can be appropriately designed to maximize the accuracy obtained from the measurements. This paper deals with the problem of designing the optimal multisine excitation for electrical bioimpedance measurements. The optimal multisine is obtained by the minimization of the Cramer-Rao lower bound, or what is the same, by maximizing the accuracy obtained from the measurements. Furthermore, because no analytical solution exists for global optimization involving time and frequency domains jointly, this paper presents the multisine optimization approach partially in both domains and then combines the results. As regards the frequency domain approach, a novel contribution is made for the multisine amplitude power spectrum. In the time domain, multisine is optimized by reducing its crest factor. Moreover, the impact on the information and accuracy of the impedance spectrum obtained from using different multisine amplitude power spectra is discussed, as well as the number of frequencies and frequency distributions. The theory is supported by a set of validation measurements when

  5. Fractal Continuation

    OpenAIRE

    Barnsley, Michael F.; Vince, Andrew

    2012-01-01

    A fractal function is a function whose graph is the attractor of an iterated function system. This paper generalizes analytic continuation of an analytic function to continuation of a fractal function.

  6. A novel broadband waterborne acoustic absorber

    Science.gov (United States)

    Wang, Changxian; Wen, Weibin; Huang, Yixing; Chen, Mingji; Lei, Hongshuai; Fang, Daining

    2016-07-01

    In this paper, we extended the ray tracing theory in polar coordinate system, and originally proposed the Snell-Descartes law in polar coordinates. Based on these theories, a novel broadband waterborne acoustic absorber device was proposed. This device is designed with gradient-distributing materials along radius, which makes the incidence acoustic wave ray warps. The echo reduction effects of this device were investigated by finite element analysis, and the numerical results show that the reflectivity of acoustic wave for the new device is lower than that of homogenous and Alberich layers in almost all frequency 0-30 kHz at the same loss factor.

  7. Advances in Low-Frequency 3-color Broadband Coherent Raman Spectroscopy of Condensed Phase Samples

    Science.gov (United States)

    Ujj, Laszlo

    2016-05-01

    Low-frequency dispersive spontaneous Raman spectroscopy is a very useful method to measure phonon frequencies in crystals or characterize collective vibrational motions of macromolecules. The coherent version of the method has not been fully explored yet. It is shown here that the 3-color Broadband Coherent Raman scattering can be a very powerful extension to not only gas phase but condensed phase low frequency (5-500 cm-1) vibrational measurements with large frequency separation between the narrowband and broadband radiation generating the signal. The spectral measurements presented here used volumetric Brag filters for the first time to record coherent Raman spectra. Specific spectral analysis using model independent methods to derive the vibrational information is also presented. The technic can be extended to measure electronic resonance enhanced spectra by tuning only the frequency of the narrowband laser close to the electronic transition frequencies. This makes the method suitable for coherent Raman microscopy. The polarization properties of the signal is also explained and experimentally verified. Financial support from the College of Sciences and Engineering of UWF is acknowledged.

  8. Ultimate VHF Broadband Interferometer Zen KAWASAKI and Manabu AKITA

    Science.gov (United States)

    Kawasaki, Z.; Akita, M.

    2013-12-01

    propagation, like electromagnetic wave propagation in non-dispersive medium. This procedure presented exciting results of lightning channel imaging, and the bi-directional leader propagation can be visualized in terms of azimuth and elevation as a function of time. Moreover all of the VHF radiation process for an entire lightning flash from initiation to termination can be imaged, and it is concluded that the system might be an ultimate broad band digital interferometer. The authors would like to show their appreciation to Paul Krehbiel, NMIMT, who gave a chance and suggestion of a continuous recording scheme for BDITF. M. Stock et al. : Continuous Broadband Digital Interferometry of Lightning using a Generalized Cross Correlation Algorithm M. Akita et al. : Data Processing Procedure 1 using Distribution of Slopes of Phase Differences for Broadband VHF Interferometer

  9. Multi-color quantum dot ensembles grown in selective-areas for shape-controlled broadband light source

    Science.gov (United States)

    Ozaki, N.; Takeuchi, K.; Ohkouchi, S.; Ikeda, N.; Sugimoto, Y.; Asakawa, K.; Hogg, R. A.

    2011-05-01

    Multi-color quantum dot (QD) ensembles were grown by selective-area growth method to realize a shape-controlled broadband light source. By using a metal-mask, QD ensembles and strain reducing layer (SRL) were formed in selective areas on a wafer. The SRL thickness was varied to achieve appropriate shifts in the peak wavelength of the QD emission spectrum up to 90 nm. A summation of PL spectra obtained from the multi-color QD ensembles shows a broadband emission spectrum with a width of approximately 120 nm, even though this spectrum is attributed to the ground state emissions of these QD ensembles. A current-induced broadband light source such as a superluminescent diode (SLD) based on the multi-color QD ensembles is expected to have an emission spectrum with a width of more than 120 nm owing to the combination of excited state emissions. Furthermore, a desired shape of the SLD spectrum can be obtained by controlling the injection current applied to each QD ensemble. This approach is promising for a shape-controlled broadband SLD, and it is particularly applicable to optical coherence tomography (OCT).

  10. Spectra and strains

    CERN Document Server

    Golyshev, V

    2008-01-01

    This is a blend of two informal reports on the activities of the seminar on Galois representations and mirror symmetry given at the Conference on classification problems and mirror duality at the Steklov Institute, in March 2006, and at the Seminar on Algebra, Geometry and Physics at MPI, in November 2007. We assess where we are on the issue of the spectra of Fano varieties, and state problems. We introduce higher dimensional irreducible analogues of dessins, the low ramified sheaves, and hypothesize that Fano spectra relate to their geometric conductors. We give a recipe to a physicist.

  11. Characterization of mechanical properties of materials using ultrasound broadband spectroscopy.

    Science.gov (United States)

    Agrawal, Megha; Prasad, Abhinav; Bellare, Jayesh R; Seshia, Ashwin A

    2016-01-01

    This article explores the characterization of homogenous materials (metals, alloys, glass and polymers) by a simple broadband ultrasonic interrogation method. The novelty lies in the use of ultrasound in a continuous way with very low input power (0 dBm or less) and analysis of the transmitted acoustic wave spectrum for material property characterization like speed of sound, density and dimensions of a material. Measurements were conducted on various thicknesses of samples immersed in liquid where continuous-wave, frequency swept ultrasonic energy was incident normal to the sample surface. The electro-acoustic transmission response is analyzed in the frequency domain with respect to a specifically constructed multi-layered analytical model. From the acoustic signature of the sample materials, material properties such as speed of sound and acoustic impedance can be calculated with experimentally derived values found to be in general agreement with the literature and with pulse-echo technique establishing the basis for a non-contact and non-destructive technique for material characterization. Further, by looking at the frequency spacing of the peaks of water when the sample is immersed, the thickness of the sample can be calculated independently from the acoustic response. This technique can prove to be an effective non-contact, non-destructive and fast material characterization technique for a wide variety of materials.

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

    Institute of Scientific and Technical Information of China (English)

    LI Shui; MIAO Rongxing

    2001-01-01

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

  13. Circularly Polarized Broadband RFID Microstrip Tag Antenna

    Directory of Open Access Journals (Sweden)

    B. Rajini

    2014-04-01

    Full Text Available In recent years, the application of radio frequency identification (RFID operating in the ultra-high frequency (UHF band (860-960MHz are expanding exponentially, due to the advantages such as long reading distance, high data transfer rate, and small tag size. So the design of a CP tag antenna with broadband characteristic is presently one of the most challenging topics. This project presents a square patch passive RFID tag antenna designed for UHF band. To achieve compact size broadband and circular polarization (CP radiation, the square patch is embedded with a cross slot, while an L-shaped open-end microstrip line coupled to the patch. By selecting an appropriate length for the microstrip line and its coupling distance with the radiating element, easy control on the input impedance of the designed tag antenna which leads to excellent impedance matching is achieved. The measured 10-dB return-loss bandwidth of the tag antenna is 27MHz (from 901–928 MHz.

  14. A Design of Double Broadband MIMO Antenna

    Directory of Open Access Journals (Sweden)

    Yanfeng Geng

    2015-01-01

    Full Text Available The MIMO antenna applied to LTE mobile system should be miniaturization and can work in the current communication frequency band; isolation between each antenna unit also should be good so as to reduce loss of radio wave energy and improve the antenna performance of the MIMO system. This paper puts forward the design scheme of a broadband MIMO double antenna. And the design of antenna unit and debugging and related technical measures, such as bending antenna bracket, are both presented; the integration design of high isolation of ultra broadband MIMO antenna is realized on the plate with the volume of 100 × 52 × 0.8 mm3; antenna working bands are 698 MHz~960 MHz and 1710 MHz~2700 MHz; in the whole spectrum, the 10 dB of port isolation can be basically achieved; in low frequency band, the isolation degree of antenna port can reach 12 dB.

  15. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    Science.gov (United States)

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-01-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe. PMID:27578317

  16. Broadband acoustic properties of a murine skull

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Turner, Jake; Razansky, Daniel

    2016-03-01

    It has been well recognized that the presence of a skull imposes harsh restrictions on the use of ultrasound and optoacoustic techniques in the study, treatment and modulation of the brain function. We propose a rigorous modeling and experimental methodology for estimating the insertion loss and the elastic constants of the skull over a wide range of frequencies and incidence angles. A point-source-like excitation of ultrawideband acoustic radiation was induced via the absorption of nanosecond duration laser pulses by a 20 μm diameter microsphere. The acoustic waves transmitted through the skull are recorded by a broadband, spherically focused ultrasound transducer. A coregistered pulse-echo ultrasound scan is subsequently performed to provide accurate skull geometry to be fed into an acoustic transmission model represented in an angular spectrum domain. The modeling predictions were validated by measurements taken from a glass cover-slip and ex vivo adult mouse skulls. The flexible semi-analytical formulation of the model allows for seamless extension to other transducer geometries and diverse experimental scenarios involving broadband acoustic transmission through locally flat solid structures. It is anticipated that accurate quantification and modeling of the skull transmission effects would ultimately allow for skull aberration correction in a broad variety of applications employing transcranial detection or transmission of high frequency ultrasound.

  17. Cascaded frequency doublers for broadband laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, N F; Vlasova, K V; Davydov, V S; Kulikov, S M; Makarov, A I; Sukharev, Stanislav A; Freidman, Gennadii I; Shubin, S V

    2012-10-31

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband ({approx}33 cm{sup -1}) single-mode fibre laser radiation with low peak power ({approx}300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency {eta} = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to {approx}30 %. (nonlinear optical phenomena)

  18. Cascaded frequency doublers for broadband laser radiation

    Science.gov (United States)

    Andreev, N. F.; Vlasova, K. V.; Davydov, V. S.; Kulikov, S. M.; Makarov, A. I.; Sukharev, Stanislav A.; Freidman, Gennadii I.; Shubin, S. V.

    2012-10-01

    A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband (~33 cm-1) single-mode fibre laser radiation with low peak power (~300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency η = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to ~30 %.

  19. A novel broadband circularly polarised monopole antenna

    Science.gov (United States)

    Kang, Ding; Cheng, Gao; Tongbin, Yu; Dexin, Qu

    2015-11-01

    A novel broadband circularly polarised (CP) monopole antenna is designed and implemented in this article. The antenna consists of a radiating patch that is composed of an annular-ring linked by a square ring over the corner and a modified ground plane. The broadband property is achieved based on a novel monopole structure that is connected by two perturbed loops, so the CP wave is generated due to the perturbation. Besides, by cutting a rectangular slit and embedding a vertical stub on the ground plane, the impedance and axial-ratio (AR) bandwidths can be greatly enhanced. The measured results reveal that the proposed monopole antenna has an impedance bandwidth of 4.575 GHz from 2.3 to 6.85 GHz, reaching the particularly broad bandwidth of 99.5%. Furthermore, a wide 3-dB AR bandwidth of 34.6% (1.53 GHz, 3.65-5.18 GHz) centred at 4.42 GHz is achieved. The radiation characteristics of the designed antenna are also presented.

  20. Adsorption of cytochrome c to silica surfaces studied using evanescent wave broadband cavity-enhanced absorption spectroscopy

    Science.gov (United States)

    Moore, L. J.; van der Sneppen, L.; Peverall, R.; Hancock, G.; Ritchie, G. A. D.

    2010-08-01

    The adsorption of cytochrome c (cyt c) to a silica surface has been studied by use of evanescent wave broadband cavityenhanced absorption spectroscopy (EW-BBCEAS). Visible radiation from a supercontinuum source is coupled into an optical cavity consisting of a pair of broadband high reflectivity mirrors, and a total internal reflection (TIR) event at the prism/water interface. Aqueous solutions of cyt c are placed onto the TIR footprint on the prism surface and the subsequent protein adsorption is probed by the resulting evanescent wave. The time integrated cavity output is directed into a spectrometer, where it is dispersed and analysed. The high spectral brilliance of the SC affords a baseline noise comparable to evanescent wave cavity ring-down spectroscopy (EW-CRDS), and the broadband nature of the source allows observation of a wide spectral range (ca 250 nm in the visible). The system is calibrated by measuring the absorption spectra of dyes of a known absorbance. Absorption spectra of cyt c are obtained for both S and P polarized radiation, allowing information about the orientation of the adsorbed protein to be extracted.

  1. Atomic Spectra Database (ASD)

    Science.gov (United States)

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  2. Techno-economic evaluation of broadband access technologies

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias; Skouby, Knud Erik

    2005-01-01

    Broadband for all is an essential element in the EU policy concerning the future of ICT-based society. The overall purpose of this paper is to present a model for evaluation of different broadband access technologies and to present some preliminary results based on the model that has been carried...

  3. 76 FR 13769 - Rural Broadband Access Loans and Loan Guarantees

    Science.gov (United States)

    2011-03-14

    ... students, parents, teachers, and school administrators has been enhanced via online forums, which is... connection. A marked difference exists, however, between urban and rural broadband use--only 70 percent of rural households with in-home Internet access had a broadband connection in 2007, compared with...

  4. 47 CFR 27.1305 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... must be designed to meet requirements associated with a nationwide, public safety broadband network. At a minimum, the network must incorporate the following features: (a) Design for operation over a... 47 Telecommunication 2 2010-10-01 2010-10-01 false Shared wireless broadband network....

  5. Broadband matched-field inversion for shallow water environment parameters

    Institute of Scientific and Technical Information of China (English)

    YANG Kunde; MA Yuanliang

    2003-01-01

    In this paper, broadband multi-frequencies matched-field inversion method is used to determine the environmental parameters in shallow water. According to different conditions, several broadband objective functions are presented. Using ASIAEX2001 experiment data and genetic algorithms, environmental parameters are obtained, especially in sediment.

  6. The role of public initiatives facilitating investments in broadband infrastructures

    DEFF Research Database (Denmark)

    Falch, Morten; Tadayoni, Reza; Henten, Anders;

    2015-01-01

    This paper discusses the role of a developmental approach to broadband policy. The policy approaches made in Denmark and Sweden are compared, and the scope for public intervention at the broadband market is discussed. The paper includes a case study on public intervention in the rural areas...

  7. Broadband tonpilz underwater acoustic transducers based on multimode optimization

    DEFF Research Database (Denmark)

    Yao, Qingshan; Jensen, Leif Bjørnø

    1997-01-01

    Head flapping has often been considered to be deleterious for obtaining a tonpilz transducer with broadband, high power performance. In the present work, broadband, high power tonpilz transducers have been designed using the finite element (FE) method. Optimized vibrational modes including the fl...

  8. The SCEC Broadband Platform: A Collaborative Open-Source Software Package for Strong Ground Motion Simulation and Validation

    Science.gov (United States)

    Silva, F.; Maechling, P. J.; Goulet, C. A.; Somerville, P.; Jordan, T. H.

    2014-12-01

    The Southern California Earthquake Center (SCEC) Broadband Platform is a collaborative software development project involving geoscientists, earthquake engineers, graduate students, and the SCEC Community Modeling Environment. The SCEC Broadband Platform (BBP) is open-source scientific software that can generate broadband (0-100Hz) ground motions for earthquakes, integrating complex scientific modules that implement rupture generation, low and high-frequency seismogram synthesis, non-linear site effects calculation, and visualization into a software system that supports easy on-demand computation of seismograms. The Broadband Platform operates in two primary modes: validation simulations and scenario simulations. In validation mode, the Platform runs earthquake rupture and wave propagation modeling software to calculate seismograms for a well-observed historical earthquake. Then, the BBP calculates a number of goodness of fit measurements that quantify how well the model-based broadband seismograms match the observed seismograms for a certain event. Based on these results, the Platform can be used to tune and validate different numerical modeling techniques. In scenario mode, the Broadband Platform can run simulations for hypothetical (scenario) earthquakes. In this mode, users input an earthquake description, a list of station names and locations, and a 1D velocity model for their region of interest, and the Broadband Platform software then calculates ground motions for the specified stations. Working in close collaboration with scientists and research engineers, the SCEC software development group continues to add new capabilities to the Broadband Platform and to release new versions as open-source scientific software distributions that can be compiled and run on many Linux computer systems. Our latest release includes 5 simulation methods, 7 simulation regions covering California, Japan, and Eastern North America, the ability to compare simulation results

  9. Determination of the broadband optical properties of biomass burning aerosol

    Science.gov (United States)

    Bluvshtein, Nir; Flores, J. Michel; Segev, Lior; Lin, Peng; Laskin, Alexander; Rudich, Yinon

    2016-04-01

    The direct and semi-direct effects of atmospheric aerosol on the Earth's energy balance are still the two of the largest uncertainties in our understanding of anthropogenic radiative forcing. In this study we developed a new approach for determining high sensitivity broadband UV-Vis spectrum (300-650 nm) of extinction, scattering and absorption coefficients, single scattering albedo and the complex refractive index for continuous, spectral and time dependent, monitoring of polydisperse aerosols population. This new approach was applied in a study of biomass burning aerosol. Extinction, scattering and absorption coefficients (αext, αsca, αabs, respectively) were continually monitored using photoacoustic spectrometer coupled to a cavity ring down spectrometer (PA-CRD-AS) at 404 nm, a dual-channel Broadband cavity-enhanced spectrometer (BBCES) at 315-345 nm and 390-420 nm and a three channel integrating nephelometer (IN) centered at 457, 525 and 637 nm. During the biomass burning event, the measured aerosol number concentration increased by more than an order of magnitude relative to other week nights and the mode of the aerosols size distribution increased from 40-50 nm to 110nm diameter. αext and αsca increased by a factor of about 5.5 and 4.5, respectively. The αabs increased by a factor over 20, indicating a significant change in the aerosol overall chemical composition. The imaginary part of the complex RI at 404nm increased from its background level at about 0.02 to a peak of about 0.08 and the SSA decreased from 0.9 to about 0.6. Significant change of the absorption spectral dependence indicates formation of visible-light absorbing compounds. The mass absorption cross section of the water soluble organic aerosol (MACWSOA) reached up to about 12% of the corresponding value for black carbon (BC) at 450 nm and up to 30% at 300 nm. These results demonstrate the importance of biomass burning in understanding global and regional radiative forcing.

  10. Anatomy of the AGN in NGC 5548. VII. Swift study of obscuration and broadband continuum variability

    Science.gov (United States)

    Mehdipour, M.; Kaastra, J. S.; Kriss, G. A.; Cappi, M.; Petrucci, P.-O.; De Marco, B.; Ponti, G.; Steenbrugge, K. C.; Behar, E.; Bianchi, S.; Branduardi-Raymont, G.; Costantini, E.; Ebrero, J.; Di Gesu, L.; Matt, G.; Paltani, S.; Peterson, B. M.; Ursini, F.; Whewell, M.

    2016-04-01

    We present our investigation into the long-term variability of the X-ray obscuration and optical-UV-X-ray continuum in the Seyfert 1 galaxy NGC 5548. In 2013 and 2014, the Swift observatory monitored NGC 5548 on average every day or two, with archival observations reaching back to 2005, totalling about 670 ks of observing time. Both broadband spectral modelling and temporal rms variability analysis are applied to the Swift data. We disentangle the variability caused by absorption, due to an obscuring weakly-ionised outflow near the disk, from variability of the intrinsic continuum components (the soft X-ray excess and the power law) originating in the disk and its associated coronae. The spectral model that we apply to this extensive Swift data is the global model that we derived for NGC 5548 from analysis of the stacked spectra from our multi-satellite campaign of 2013 (including XMM-Newton, NuSTAR, and HST). The results of our Swift study show that changes in the covering fraction of the obscurer is the primary and dominant cause of variability in the soft X-ray band on timescales of 10 days to ~5 months. The obscuring covering fraction of the X-ray source is found to range between 0.7 and nearly 1.0. The contribution of the soft excess component to the X-ray variability is often much less than that of the obscurer, but it becomes comparable when the optical-UV continuum flares up. We find that the soft excess is consistent with being the high-energy tail of the optical-UV continuum and can be explained by warm Comptonisation: up-scattering of the disk seed photons in a warm, optically thick corona as part of the inner disk. To this date, the Swift monitoring of NGC 5548 shows that the obscurer has been continuously present in our line of sight for at least 4 years (since at least February 2012).

  11. On the scenario of transition to the broadband oscillation regime in the prototype of a low-voltage vircator

    Science.gov (United States)

    Kalinin, Yu. A.; Starodubov, A. V.; Kuznetsov, N. N.

    2013-06-01

    This study is devoted to experimental investigation of the scenario for a transition from the narrow-band (single-frequency) oscillation regime to the broadband noise-like oscillation in a prototype of a low-voltage oscillator operating with a virtual cathode. The experimental setup and the control instrumentation are considered. Detailed experimental analysis of the dynamics of variation of temporal realizations of the signals generated by the laboratory prototype upon the variation of the chosen control parameters is performed. Analysis of the power spectra, temporal realizations of output signals, phase portraits, and the bifurcation diagram constructed upon a change of the chosen control parameters shows that a transition from the single-frequency oscillation regime to broadband oscillations occurs via a cascade of period-doubling bifurcations (classical Feugenbaum scenario is implemented).

  12. The SCEC Broadband Platform: A Collaborative Open-Source Software Package for Strong Ground Motion Simulation and Validation

    Science.gov (United States)

    Silva, F.; Maechling, P. J.; Goulet, C.; Somerville, P.; Jordan, T. H.

    2013-12-01

    Platform facilitates the addition of new scientific methods, which are written by earth scientists in a number of languages such as C, C++, Fortran, and Python. The Broadband Platform's modular design also supports the reuse of existing software modules as building blocks to create new scientific methods. Additionally, the Platform implements a wrapper around each scientific module, converting input and output files to and from the specific formats required (or produced) by individual scientific codes. Working in close collaboration with scientists and research engineers, the SCEC software development group continues to add new capabilities to the Broadband Platform and to release new versions as open-source scientific software distributions that can be compiled and run on many Linux computer systems. Our latest release includes the addition of 3 new simulation methods and several new data products, such as map and distance-based goodness of fit plots. Finally, as the number and complexity of scenarios simulated using the Broadband Platform increase, we have added batching utilities to substantially improve support for running large-scale simulations on computing clusters.

  13. Broadband Optical Access Technologies to Converge towards a Broadband Society in Europe

    Science.gov (United States)

    Coudreuse, Jean-Pierre; Pautonnier, Sophie; Lavillonnière, Eric; Didierjean, Sylvain; Hilt, Benoît; Kida, Toshimichi; Oshima, Kazuyoshi

    This paper provides insights on the status of broadband optical access market and technologies in Europe and on the expected trends for the next generation optical access networks. The final target for most operators, cities or any other player is of course FTTH (Fibre To The Home) deployment although we can expect intermediate steps with copper or wireless technologies. Among the two candidate architectures for FTTH, PON (Passive Optical Network) is by far the most attractive and cost effective solution. We also demonstrate that Ethernet based optical access network is very adequate to all-IP networks without any incidence on the level of quality of service. Finally, we provide feedback from a FTTH pilot network in Colmar (France) based on Gigabit Ethernet PON technology. The interest of this pilot lies on the level of functionality required for broadband optical access networks but also on the development of new home network configurations.

  14. Local Implementation of a Broadband Network: Social Impact issues of New Broadband Capacity in Australia

    OpenAIRE

    Tiffany Amber Tenty; Brendan Wallis; Sumita Ghosh; Richard Howitt

    2012-01-01

    In April 2009, the Australian Government announced plans to roll-out the National Broadband Network (NBN) Company Open Access Network in Australia. Australia’s NBN will bring high speed internet access to areas and people that otherwise would have been without. Predicting consequences (both positive and negative) arising from the NBN, as well as risks and opportunities that it will generate differentially between places, groups and sectors, is inherently uncertain. With little reliable data a...

  15. Resource Management in Broadband Communication Networks

    DEFF Research Database (Denmark)

    Hansen, Mads Stenhuus

    2003-01-01

    This thesis - Resource Management in Broadband Communication Networks - deals with different ways of optimizing the available resources of data- or telecommunication networks. Especially topics like optimal routing, load balancing and fast recovery of routes in case of link failures are covered......, that reflects the situation in a competitive telecommunication market, with several service providers sharing the same physical network. The investigation of the simulated ants, on the other hand, gives a many promising results, suggesting that they can successfully be used to solve some problems...... a virtually unprecedented robustness. A network with failing components typically return to a fully operational state within seconds or even faster. Hopefully these results of the investigation of simulated ants - along with other results from the literature - can contribute to make the big manufacturers...

  16. Broadband phase-preserved optical elevator

    CERN Document Server

    Luo, Yuan; Zhang, Baile; Qiu, Cheng-Wei; Barbastathis, George

    2011-01-01

    Phase-preserved optical elevator is an optical device to lift up an entire plane virtually without distortion in light path or phase. Using transformation optics, we have predicted and observed the realization of such a broadband phase-preserved optical elevator, made of a natural homogeneous birefringent crystal without resorting to absorptive and narrowband metamaterials involving time-consuming nano-fabrication. In our demonstration, the optical elevator is designed to lift a sheet upwards, and the phase is verified to be preserved always. The camouflage capability is also demonstrated in the presence of adjacent objects of the same scale at will. The elevating device functions in different surrounding media over the wavelength range of 400-700 nm. Our work opens up prospects for studies of light trapping, solar energy, illusion optics, communication, and imaging.

  17. Broadband Multifocal Conic-Shaped Metalens

    CERN Document Server

    Bao, Yanjun; Fang, Zheyu

    2016-01-01

    Compared with lens with one focal point,multifocal lens has a lower focusing quality with high background noise. This is arisen from the construction of multifocal lens, which is usually divided into several zones, with each corresponds to one focal point.Light passing through different zones cannot constructively interfere at the foci, resulting in a decreased optical performance. Here, we propose two multifocal metalenses with nanoslits arranged in an ellipse and a hyperbola, with both are able to focus incident light at their multifoci constructively, giving a better focusing properties than that designed by conventional methods.We theoretically and experimentally demonstrate that, within a broadband wavelength range (600-900 nm), the ellipse-shaped metalens (ESM) can focus the lights with opposite circular polarizations (CP) at its two focal points, respectively,while a hyperbola-shaped metalens (HSM) can only focus one particular CP light at its both foci, simultaneously.This types of conic-shaped metale...

  18. Broad-band multisection electrooptic modulators

    Science.gov (United States)

    Lax, Benjamin; Marino, Richard M.; Eng, Richard S.

    1988-10-01

    A general solution has been derived for expressing the conversion of power from a base frequency to a modulation sideband using a multisection electrooptic modulator. The objective is to obtain broadband frequency modulation of a laser by the use of multiple collinear electrooptic crystals with microwave power levels well below the breakdown threshold. It is found that segmented structures lead to greater bandwidths, which increase with the number of modulator sections. This is achieved by adjusting the phases of microwaves between sections to maximize the single-sideband conversion efficiency. It is shown that a 10.6-micron CO2 laser modulator with six geometrically identical CdTe sections can potentially achieve a 3-dB bandwidth of nearly 6 GHz using a 10-kW traveling-wave tube operating at 16-GHz center frequency.

  19. Future large broadband switched satellite communications networks

    Science.gov (United States)

    Staelin, D. H.; Harvey, R. R.

    1979-01-01

    Critical technical, market, and policy issues relevant to future large broadband switched satellite networks are summarized. Our market projections for the period 1980 to 2000 are compared. Clusters of switched satellites, in lieu of large platforms, etc., are shown to have significant advantages. Analysis of an optimum terrestrial network architecture suggests the proper densities of ground stations and that link reliabilities 99.99% may entail less than a 10% cost premium for diversity protection at 20/30 GHz. These analyses suggest that system costs increase as the 0.6 power of traffic. Cost estimates for nominal 20/30 GHz satellite and ground facilities suggest optimum system configurations might employ satellites with 285 beams, multiple TDMA bands each carrying 256 Mbps, and 16 ft ground station antennas. A nominal development program is outlined.

  20. Broadband interferometer observations of a triggered lightning

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The development of positive leader of an artificially triggered lightning has been analyzed based on the data of electric field change, location of radiation source and frequency spectrum obtained by using the broadband interferometer system. The results indicate that radiation from positive leader could be detected within close distance in spite of the relatively weak radiation, while the radiation from negative breakdown processes was relatively stronger.Positive leader developed with few branches, and the initial progression velocity was of the order of 10s m/s. The distribution of power spectrum by 25 MHz high pass filter indicated that the radiation frequency from positive leader maximized at 25-30 MHz, while that from negative breakdown processes maximized at 60-70 MHz.

  1. Hot Carrier extraction with plasmonic broadband absorbers

    CERN Document Server

    Ng, Charlene; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gomez, Daniel E

    2016-01-01

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photo-catalysis, photovoltaics and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multi-stack layered configuration to achieve broad-band, near-unit light absorption, which is spatially localised on the nanoparticle layer. We show that this enhanced light absorbance leads to $\\sim$ 40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot-electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where the photons possessing energies higher than the S...

  2. Broadband plasmon induced transparency in terahertz metamaterials

    KAUST Repository

    Zhu, Zhihua

    2013-04-25

    Plasmon induced transparency (PIT) could be realized in metamaterials via interference between different resonance modes. Within the sharp transparency window, the high dispersion of the medium may lead to remarkable slow light phenomena and an enhanced nonlinear effect. However, the transparency mode is normally localized in a narrow frequency band, which thus restricts many of its applications. Here we present the simulation, implementation, and measurement of a broadband PIT metamaterial functioning in the terahertz regime. By integrating four U-shape resonators around a central bar resonator, a broad transparency window across a frequency range greater than 0.40 THz is obtained, with a central resonance frequency located at 1.01 THz. Such PIT metamaterials are promising candidates for designing slow light devices, highly sensitive sensors, and nonlinear elements operating over a broad frequency range. © 2013 IOP Publishing Ltd.

  3. Ultra-broadband terahertz metamaterial absorber

    Science.gov (United States)

    Zhu, Jianfei; Ma, Zhaofeng; Sun, Wujiong; Ding, Fei; He, Qiong; Zhou, Lei; Ma, Yungui

    2014-07-01

    We demonstrated an ultra-broadband, polarization-insensitive, and wide-angle metamaterial absorber for terahertz (THz) frequencies using arrays of truncated pyramid unit structure made of metal-dielectric multilayer composite. In our design, each sub-layer behaving as an effective waveguide is gradually modified in their lateral width to realize a wideband response by effectively stitching together the resonance bands of different waveguide modes. Experimentally, our five layer sample with a total thickness 21 μm is capable of producing a large absorptivity above 80% from 0.7 to 2.3 THz up to the maximum measurement angle 40°. The full absorption width at half maximum of our device is around 127%, greater than those previously reported for THz frequencies. Our absorber design has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.

  4. Modeling Broadband motions from the Tohoku earthquake

    Science.gov (United States)

    Li, D.; Chu, R.; Graves, R. W.; Helmberger, D. V.; Clayton, R. W.

    2011-12-01

    The 2011 M9 Tohoku earthquake produced an extraordinary dataset of over 2000 broadband regional and teleseismic records. While considerable progress has been made in modeling the longer period (>3 s) waveforms, the shorter periods (1-3 s) prove more difficult. Since modeling high frequency waveforms in 3D is computationally expensive, we follow the approach proposed by Helmberger and Vidale (1988), which interfaces the Cagniard-de Hoop analytical source description with a 2D numerical code to account for earthquake radiation patterns. We extend this method to a staggered grid finite difference code, which is stable in the presence of water. The code adapts the Convolutional PML boundary condition, and uses the "following the wavefront" technique and multiple GPUs, which significantly reduces computing time. We test our method against existing 1D and 3D codes, and examine the effects of slab structure, ocean bathymetry and local basins in an attempt to better explain the observed shorter period response.

  5. Broadband Approximations for Doubly Curved Reflector Antenna

    Directory of Open Access Journals (Sweden)

    V. Schejbal

    2010-12-01

    Full Text Available The broadband approximations for shaped-beam doubly curved reflector antennas with primary feed (rectangular horn producing uniform amplitude and phase aperture distribution are derived and analyzed. They are very valuable for electromagnetic compatibility analyses both from electromagnetic interference and susceptibility point of view, because specialized more accurate methods such as physical optics are only used by antenna designers. To allow quick EMC analyses, typical values, beamwidth changes, sidelobe levels and aperture efficiencies are given for frequency changes approximately up to four times operating frequency. A comparison of approximated and measured patterns of doubly curved reflector antennas shows that the given approximation could be reliably used for analyses of pattern changes due to very broad frequency changes.

  6. Broadband acoustic cloak for ultrasound waves.

    Science.gov (United States)

    Zhang, Shu; Xia, Chunguang; Fang, Nicholas

    2011-01-14

    Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely, serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Because of the nonresonant nature of the building elements, this low-loss (∼6  dB/m) cylindrical cloak exhibits invisibility over a broad frequency range from 52 to 64 kHz. Furthermore, our experimental study indicates that this design approach should be scalable to different acoustic frequencies and offers the possibility for a variety of devices based on coordinate transformation.

  7. Statistical dispersion relation for spatially broadband fields.

    Science.gov (United States)

    Shan, Mingguang; Nastasa, Viorel; Popescu, Gabriel

    2016-06-01

    The dispersion relation is fundamental to a physical phenomenon that develops in both space and time. This equation connects the spatial and temporal frequencies involved in the dynamic process through the material constants. Electromagnetic plane waves propagating in homogeneous media are bound by simple dispersion relation, which sets the magnitude of the spatial frequency, k, as being proportional to the temporal frequency, ω, with the proportionality constant dependent on the refractive index, n, and the speed of light in vacuum, c. Here we show that, for spatially broadband fields, an analog dispersion relation can be derived, except in this case the k-vector variance is connected with the temporal frequency through the statistics of the refractive index fluctuations in the medium. We discuss how this relationship can be used to retrieve information about refractive index distributions in biological tissues. This result is particularly significant in measurements of angular light scattering and quantitative phase imaging of biological structures. PMID:27244396

  8. A compact broadband nonsynchronous noncommensurate impedance transformer

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, Kseniya; Narenda, Kumar

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison to the tradit......Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison...... to the traditional tapered line transformers. This flexibility of the broadband nonsynchronous noncommensurate impedance transformers is experimentally demonstrated in this article allowing the length reduction by almost three times. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1832–1835, 2012; View...

  9. Analytical reconstruction of isotropic turbulence spectra based on the Gaussian transform

    OpenAIRE

    Wohlbrandt, Attila; Hu, Nan; Guerin, Sebastien; Ewert, Roland

    2015-01-01

    The Random Particle Mesh (RPM) method used to simulate turbulence-induced broadband noise in several aeroacoustic applications is extended to realise isotropic turbulence spectra. With this method turbulent fluctuations are synthesised by filtering white noise with a Gaussian filter kernel that in turn gives a Gaussian spectrum. The Gaussian function is smooth and its derivatives and integrals are again Gaussian functions. The Gaussian filter is efficient and finds wide-spread applications in...

  10. The broadband spectrum of Centaurus X-3

    Science.gov (United States)

    Gottlieb, Amy; Pottschmidt, Katja; Marcu, Diana; Wolff, Michael Thomas; Kühnel, Matthias; Falkner, Sebastian; Britton Hemphill, Paul; Suchy, Slawomir; Becker, Peter A.; Wood, Kent S.; Wilms, Joern

    2016-04-01

    We present an analysis of a Suzaku observation of the accreting pulsar and high mass X-ray binary Centaurus X-3. The observation was performed in 2008 and covers one 2.1 day binary orbit. Strong flux and hardness variability is present in the energy range from 0.8 to 60 keV. We selected a part of the observation covering ~40% of the first half of the orbit during which the spectral shape was stable and less absorbed than during other parts of the observation. We confirm earlier results that the broadband spectrum can be modeled with acutoff power law modified by a partial absorber, three iron lines -- from near-neutral, helium-like, and hydrogen-like iron --, and a cyclotron resonant scattering line at 30 keV. The pulse profile shows a shift above the cyclotron line energy which is qualitatively consistent with recent theoretical predictions. In addition we findthat the presence of the so-called ``13 keV'' bump is model dependent and that there are indications for further line-like spectral components at 1 keV and 6 keV and a broader residual around 2 keV. We also apply the newly implemented radiation dominated radiative shock model for luminous accretion pulsars by Becker and Wolff (2007, ApJ 654, 435) to model the broadband spectrum. Replacing the cutoff power law with the physical continuum while retaining all other components we obtain a similar goodness of fit as before. From the physical continuum model we determine a mass accretion rate of ~2.17 x 10^17 g/s, an accretion column radius of 65 (+12, -4) m, and a temperature of the accreted plasma of 3.1 (+0.4, -0.1) keV.

  11. Local Implementation of a Broadband Network: Social Impact issues of New Broadband Capacity in Australia

    Directory of Open Access Journals (Sweden)

    Tiffany Amber Tenty

    2012-12-01

    Full Text Available In April 2009, the Australian Government announced plans to roll-out the National Broadband Network (NBN Company Open Access Network in Australia. Australia’s NBN will bring high speed internet access to areas and people that otherwise would have been without. Predicting consequences (both positive and negative arising from the NBN, as well as risks and opportunities that it will generate differentially between places, groups and sectors, is inherently uncertain. With little reliable data available on social impacts of NBN-style access at the household and community level, policy-making and regulation risks responding to optimistic speculation and commercially motivated spin rather than carefully weighed evidence. The research reported in this paper aimed to address this gap with a preliminary assessment of the social impacts of the NBN-like broadband roll-out at one New South Wales test site in southwest Sydney. The paper discusses the research methods and findings and frames recommendations for further research to address both limitations that arose in the research reported here, and broader gaps in understanding the social impacts of new forms of broadband access and associated applications. Keywords: Social Impacts, Communication Technologies, High Speed Internet

  12. Collective spectra along the fission barrier

    Directory of Open Access Journals (Sweden)

    Pigni M. T.

    2012-12-01

    Full Text Available Discrete and continuous spectra of fissioning nuclei at the humps of fission barriers (Bohr transition states and in the intermediate wells (superdeformed and hyperdeformed states play a key role in the calculation of fission cross sections. A theoretical evaluation of the collective parts of the spectra is possible within the framework of the dinuclear system model, which treats the wave function of the fissioning nucleus as a superposition of a mononucleus configuration and two–cluster configurations in a dynamical way, permitting exchange of upper–shell nucleons between clusters. The impact of theoretical spectra on neutron–induced fission cross sections and, in combination with an improved version of the scission–point model, on angular distribution of fission fragments is evaluated for plutonium isotopes of interest to nuclear energy applications.

  13. Broadband metasurfaces for anomalous transmission and spectrum splitting at visible frequencies

    Directory of Open Access Journals (Sweden)

    Li Zhongyang

    2015-01-01

    Full Text Available The emergent ultrathin metasurfaces are promising optical materials to enable novel photonic functionality and miniature optical devices. By elaborately design the interfacial phase shift from discrete nanoantennas with distinctive geometries, metasurfaces have the potential to shape desired wavefronts and arbitrary steer light propagation. However, the realization of broadband transmission-mode metasurfaces that operates at visible frequencies have still been significant challenging. Because it is difficult to achieve drastic broadband optical response depending on discrete plasmonic resonators and the fabrication of such subwavelength-size resonators with high uniformity is also challenging. Here, we propose an efficient yet a simple transmission-mode metasurface design comprising of a single, quasi-continuous nanoantenna as the build block. Each nanoantenna consist of a trapezoid-shaped triple-layered (Ag-SiO2-Ag plasmonic resonator which could induce drastic gradient phase shifts for transmitted light. We numerically demonstrated broadband (500–850 nm anomalous transmitted propagation and spectrum splitting at visible frequencies and beyond. The average power ratio of anomalous transmission mode to the first-order diffraction mode was calculated to be ~1000. Such proposed metasurface design is a clear departure from conventional metasurfaces utilizing multiple discrete resonators, and suggests applications for achieving ultrathin lenses, high SNR spectrometers, directional emitters and spectrum splitting surfaces for photovoltaics.

  14. Business continuity

    International Nuclear Information System (INIS)

    This presentation deals with the following keypoints: Information Technology (IT) Business Continuity and Recovery essential for any business; lessons learned after Sept. 11 event; Detailed planning, redundancy and testing being the key elements for probability estimation of disasters

  15. Continuing Care

    Science.gov (United States)

    ... Care Obesity at Midlife May Speed Alzheimer’s Onset Hello from my mom Easing the Behavior Problems of ... Managers Continuing Care FOR MORE ARTICLES CLICK HERE Hello from my mom Common Estate Planning Errors Alzheimer’s ...

  16. Ultra-broadband perfect cross polarization conversion metasurface

    Science.gov (United States)

    Dong, Guoxiang; Shi, Hongyu; Xia, Song; Zhang, Anxue; Xu, Zhuo; Wei, Xiaoyong

    2016-04-01

    We propose a metasurface with multiple plasmon resonances that achieves an ultra-broadband perfect cross polarization conversion. The metasurface is composed of an array of unit resonators, three plasmon resonances are excited in the unit resonator, which leads to an ultra-broadband perfect cross polarization conversion. The cross polarization conversion efficiency is higher than 99%, and the bandwidth of the converter is 53.7% of the central wavelength. Both numerical and experimental results were used to validate the ultra-broadband perfect cross polarization converter presented here.

  17. The Social Impact Of Broadband Household Internet Access

    OpenAIRE

    Anderson, Ben

    2008-01-01

    Broadband changes everything. Or so we are told. But does it? There is only one way to find out - follow people who move from narrowband to broadband internet access and see what changes. This paper reports exactly this kind of analysis using data from a two wave European panel study (e-Living) and the lagged endogenous regression approach to see if switching to broadband increases the time spent online, the use of online communication services, the breadth of internet activities and the amou...

  18. X-ray spectra for mamography

    International Nuclear Information System (INIS)

    By means of Monte Carlo methods the X-ray spectra that produce Mammography equipment have been obtained. The mammographs are widely used with the purpose of diagnosing the cancer of the mammary glands. Different makers and mammographs models are distinguished by the voltage capacity and the current, exist as well as in the target type and filter. The targets that are used are Mo, Rh and W and the filters are Mo, Rh, Al and Be. In this work the results obtained by means of the MCNP code of the X-ray spectra take place when an electron beam of 28 keV is made impact on Mo, Rh and W targets, as well as the spectra that result of filtering these X rays using different types of filters. The resulting spectra contain the continuous spectrum of the stopping radiation, as well as the X rays characteristic of the used target. The utility of estimating the spectra of X rays by means of Monte Carlo is that it can use to estimate the absorbed dose by the gland, as well as the absorbed dose by other organs. It also allows to calculate the detector response. (Author)

  19. A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection

    International Nuclear Information System (INIS)

    A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors' reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument's two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO2 (versus a laser broadband cavity ringdown spectrometer) and for H2O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer-Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor's 4v+δ absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument's detection limits for NO3 as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1σ detection limit of 0.25 pptv for a 10 s

  20. Deconvolution of Positrons' Lifetime spectra

    International Nuclear Information System (INIS)

    In this paper, we explain the iterative method previously develop for the deconvolution of Doppler broadening spectra using the mathematical optimization theory. Also, we start the adaptation and application of this method to the deconvolution of positrons' lifetime annihilation spectra

  1. Band edge identification and carrier dynamics of CVD MoS2 monolayer measured by broadband Femtosecond Transient Absorption Spectroscopy

    Science.gov (United States)

    Aleithan, Shrouq; Livshits, Maksim; Rack, Jeffrey; Kordesch, Martin; Stinaff, Eric

    Two-dimensional atomic crystals of transition metal dichalcogenides are considered promising candidates for optoelectronics, valleytronics, and energy harvesting devices. These materials exhibit excitonic features with high binding energy as a result of confinement effect and reduced screening when the material is thinned to monolayer. However, previous theoretical and experimental studies report different binding energy results. This work further examines the electronic structure and binding energy in this material using broadband Femtosecond Transient Absorption Spectroscopy. Samples of MoS2 were grown by chemical vapor deposition, pumped with femtosecond laser, and probed by femtosecond white light resulting in broadband differential absorption spectra with three distinct features related to the three dominant absorption peaks in the material: A, B, and C. The dependence of the transient absorption spectra on excitation wavelength and layer number provides evidence of a band gap located at C (2.9 eV) and therefore an excitonic binding energy of 1 eV. Additional features in the spectra identified as a broadening of the absorption features caused by carrier scattering, surface defects and trap states.

  2. Microelectromechanical Systems (MEMS) Broadband Light Source Developed

    Science.gov (United States)

    Tuma, Margaret L.

    2003-01-01

    A miniature, low-power broadband light source has been developed for aerospace applications, including calibrating spectrometers and powering miniature optical sensors. The initial motivation for this research was based on flight tests of a Fabry-Perot fiberoptic temperature sensor system used to detect aircraft engine exhaust gas temperature. Although the feasibility of the sensor system was proven, the commercial light source optically powering the device was identified as a critical component requiring improvement. Problems with the light source included a long stabilization time (approximately 1 hr), a large amount of heat generation, and a large input electrical power (6.5 W). Thus, we developed a new light source to enable the use of broadband optical sensors in aerospace applications. Semiconductor chip-based light sources, such as lasers and light-emitting diodes, have a relatively narrow range of emission wavelengths in comparison to incandescent sources. Incandescent light sources emit broadband radiation from visible to infrared wavelengths; the intensity at each wavelength is determined by the filament temperature and the materials chosen for the filament and the lamp window. However, present commercial incandescent light sources are large in size and inefficient, requiring several watts of electrical power to obtain the desired optical power, and they emit a large percentage of the input power as heat that must be dissipated. The miniature light source, developed jointly by the NASA Glenn Research Center, the Jet Propulsion Laboratory, and the Lighting Innovations Institute, requires one-fifth the electrical input power of some commercial light sources, while providing similar output light power that is easily coupled to an optical fiber. Furthermore, it is small, rugged, and lightweight. Microfabrication technology was used to reduce the size, weight, power consumption, and potential cost-parameters critical to future aerospace applications. This chip

  3. Meteors and meteorites spectra

    Science.gov (United States)

    Koukal, J.; Srba, J.; Gorková, S.; Lenža, L.; Ferus, M.; Civiš, S.; Knížek, A.; Kubelík, P.; Kaiserová, T.; Váňa, P.

    2016-01-01

    The main goal of our meteor spectroscopy project is to better understand the physical and chemical properties of meteoroids. Astrometric and spectral observations of real meteors are obtained via spectroscopic CCD video systems. Processed meteor data are inserted to the EDMOND database (European viDeo MeteOr Network Database) together with spectral information. The fully analyzed atmospheric trajectory, orbit and also spectra of a Leonid meteor/meteoroid captured in November 2015 are presented as an example. At the same time, our target is the systematization of spectroscopic emission lines for the comparative analysis of meteor spectra. Meteoroid plasma was simulated in a laboratory by laser ablation of meteorites samples using an (ArF) excimer laser and the LIDB (Laser Induced Dielectric Breakdown) in a low pressure atmosphere and various gases. The induced plasma emissions were simultaneously observed with the Echelle Spectrograph and the same CCD video spectral camera as used for real meteor registration. Measurements and analysis results for few selected meteorite samples are presented and discussed.

  4. Continuity theory

    CERN Document Server

    Nel, Louis

    2016-01-01

    This book presents a detailed, self-contained theory of continuous mappings. It is mainly addressed to students who have already studied these mappings in the setting of metric spaces, as well as multidimensional differential calculus. The needed background facts about sets, metric spaces and linear algebra are developed in detail, so as to provide a seamless transition between students' previous studies and new material. In view of its many novel features, this book will be of interest also to mature readers who have studied continuous mappings from the subject's classical texts and wish to become acquainted with a new approach. The theory of continuous mappings serves as infrastructure for more specialized mathematical theories like differential equations, integral equations, operator theory, dynamical systems, global analysis, topological groups, topological rings and many more. In light of the centrality of the topic, a book of this kind fits a variety of applications, especially those that contribute to ...

  5. Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan Kien-Kwok; Liao, Bolin; Chen, Gang

    2015-04-21

    A system for measuring the absorption spectrum of a sample is provided that includes a broadband light source that produces broadband light defined within a range of an absorptance spectrum. An interferometer modulates the intensity of the broadband light source for a range of modulation frequencies. A bi-layer cantilever probe arm is thermally connected to a sample arm having at most two layers of materials. The broadband light modulated by the interferometer is directed towards the sample and absorbed by the sample and converted into heat, which causes a temperature rise and bending of the bi-layer cantilever probe arm. A detector mechanism measures and records the deflection of the probe arm so as to obtain the absorptance spectrum of the sample.

  6. Variation of focal switch with spectrum of a broadband laser

    Science.gov (United States)

    Zhang, Biyu; Peng, Runwu; Xie, Haiqing; Zhang, Wei

    2016-05-01

    Effects of the spectrum on focal switch of a broadband laser in a dispersion dual-focus system are presented in this paper. The numerical results show that the two maximum intensities of the broadband laser on the z-axis vary when the central frequency of the broadband laser shifts and the spectrum shape changes, and the variations affect the generation of the focal switch. It is also found that difference of the two maximum intensities tends to increase when the absolute value of central wavelength increases. According to the results in this paper, the generation of the focal switch can be controlled by choosing the shift of the central frequency, the bandwidth, the distance between the two lenses, and the spectrum shape of the broadband laser.

  7. Exploiting Narrowband Efficiency for Broadband Convolutive Blind Source Separation

    Directory of Open Access Journals (Sweden)

    Aichner Robert

    2007-01-01

    Full Text Available Based on a recently presented generic broadband blind source separation (BSS algorithm for convolutive mixtures, we propose in this paper a novel algorithm combining advantages of broadband algorithms with the computational efficiency of narrowband techniques. By selective application of the Szegö theorem which relates properties of Toeplitz and circulant matrices, a new normalization is derived as a special case of the generic broadband algorithm. This results in a computationally efficient and fast converging algorithm without introducing typical narrowband problems such as the internal permutation problem or circularity effects. Moreover, a novel regularization method for the generic broadband algorithm is proposed and subsequently also derived for the proposed algorithm. Experimental results in realistic acoustic environments show improved performance of the novel algorithm compared to previous approximations.

  8. Broadband Wireless Data Acquisition and Control Device Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mobitrum is proposing to develop a broadband wireless device for real-time data acquisition and monitoring applicable to the field instrumentation and control...

  9. Broadband nulling behaviour of PSR B2319+60

    CERN Document Server

    Gajjar, Vishal; Kramer, M

    2012-01-01

    Pulse nulling is one of many single pulse phenomena exhibited by radio pulsars. The broadband nature of this phenomena remained unexplained due to lack of coordinated observations. We are reporting broadband nulling behaviour of a well known nulling pulsar PSR B2319+60. The simultaneous observations were carried out at four different frequencies using the Giant Meterwave Radio telescope (325 and 610 MHz), the Westerbork Synthesis Radio Telescope (1420 MHz) and the Effelsberg radio telescope (5100 MHz). The nulling fractions were estimated at all four observed frequencies, which suggest similar degree of nulling across these frequencies. To comment on the broadband behaviour of pulse nulling, we calculated the Pearson cross-correlation coefficients for the occurrence of null and burst pulses between all four frequencies. We conclude that nulling is largely a broadband phenomenon for this pulsar and it points towards a global failure of the magnetospheric currents which produces radio emission at these frequenc...

  10. Twisted optical metamaterials for planarized ultrathin broadband circular polarizers.

    Science.gov (United States)

    Zhao, Y; Belkin, M A; Alù, A

    2012-05-29

    Optical metamaterials are usually based on planarized, complex-shaped, resonant nano-inclusions. Three-dimensional geometries may provide a wider set of functionalities, including broadband chirality to manipulate circular polarization at the nanoscale, but their fabrication becomes challenging as their dimensions get smaller. Here we introduce a new paradigm for the realization of optical metamaterials, showing that three-dimensional effects may be obtained without complicated inclusions, but instead by tailoring the relative orientation within the lattice. We apply this concept to realize planarized, broadband bianisotropic metamaterials as stacked nanorod arrays with a tailored rotational twist. Because of the coupling among closely spaced twisted plasmonic metasurfaces, metamaterials realized with conventional lithography may effectively operate as three-dimensional helical structures with broadband bianisotropic optical response. The proposed concept is also shown to relax alignment requirements common in three-dimensional metamaterial designs. The realized sample constitutes an ultrathin, broadband circular polarizer that may be directly integrated within nanophotonic systems.

  11. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal

    2013-01-01

    In this paper, design based on tapered circular grating structure was studied, to provide broadband enhancement in thin film amorphous silicon solar cells. In comparison to planar structure an absorption enhancement of ~ 7% was realized.

  12. Broadband Reflective Coating Process for Large FUVOIR Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ZeCoat Corporation will develop and demonstrate a set of revolutionary coating processes for making broadband reflective coatings suitable for very large mirrors...

  13. Broadband optical gain in the normally dispersive region of a high-birefringence photonic crystal fiber

    International Nuclear Information System (INIS)

    Based on a designed high-birefringence photonic crystal fiber (HB-PCF) with two zero-dispersion wavelengths (ZDWs), the effect of pump parameters and Raman scattering on the modulation instability (MI) gain is comprehensively analyzed in this paper. An interesting result is found, in that only when the pump wavelength lies within an approximately 10 nm range of the zero-dispersion points in the normal dispersion region of the HB-PCF does a broadband gain characteristic appear. The Raman effect results in a combination of the gain spectra from the Stokes and anti-Stokes band, which finally promotes the formation of broadband amplification. Moreover, there exist an optimal pump wavelength and a suitable pump power along the fast axis or the slow axis of the fiber. With these optimal pump parameters, the total MI gain bandwidth finally reaches 159 nm for the fiber fast axis and 162 nm for the fiber slow axis. (paper)

  14. Spectroscopic benzene detection using a broadband monolithic DFB-QCL array

    Science.gov (United States)

    Lewicki, Rafał; Witinski, Mark; Li, Biao; Wysocki, Gerard

    2016-03-01

    Quantitative laser spectroscopic measurements of complex molecules that have a broad absorption spectra require broadly tunable laser sources operating preferably in the mid-infrared molecular fingerprint region. In this paper a novel broadband mid-infrared laser source comprising of an array of single-mode distributed feedback quantum cascade lasers was used to target a broadband absorption feature of benzene (C6H6), a toxic and carcinogenic atmospheric pollutant. The DFB-QCL array is a monolithic semiconductor device with no opto-mechanical components, which eliminates issues with mechanical vibrations. The DFB-QCLs array used in this work provides spectral coverage from 1022.5 cm-1 to 1053.3 cm-1, which is sufficient to access the absorption feature of benzene at 1038 cm-1 (9.64 μm). A sensor prototype based on a 76 m multipass cell (AMAC-76LW, Aerodyne Research) and a dispersive DFB-QCL array beam combiner was developed and tested. The Allan deviation analysis of the retrieved benzene concentration data yields a short-term precision of 100 ppbv/Hz1/2 and a minimum detectable concentration of 12 ppbv for 200 s averaging time. The system was also tested by sampling atmospheric air as well as vapors of different chemical products that contained traces of benzene.

  15. Design of tri-level excitation signals for broadband bioimpedance spectroscopy.

    Science.gov (United States)

    Yang, Yuxiang; Wang, Lianhuan; Wang, Peipei; Yang, Xiufang; Zhang, Fu; Wen, He; Teng, Zhaosheng

    2015-09-01

    Bioimpedance spectroscopy (BIS) measurement methods have been evolving from the traditional frequency-sweep approach to the multi-frequency simultaneous measurement technique which can drastically reduce measuring time and will be increasingly attractive for time-varying biological applications. Multi-frequency mixed (MFM) signals with sparsely distributed spectra are desirable for broadband BIS measurement. This paper proposes a synthesis method to design a series of tri-level MFM signals which contain only three values (+1, 0, -1), and has majority energy distributed on its (2(n))th primary harmonics. Tri-level MFM signals have both high energy efficiency and a low crest factor. An impedance measurement experiment excited by an 8th-order tri-level MFM signal on a RC three-element equivalent model has been performed, and the results on 8 primary harmonic frequencies ranging from 8 to 1024 kHz show a high accuracy with the mean amplitude relative error of 0.41% and mean phase absolute error of 0.18°, which has validated the feasibility of the tri-level MFM signals for broadband BIS measurement. PMID:26261063

  16. Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS – applicability and corrections

    Directory of Open Access Journals (Sweden)

    D. Pöhler

    2009-11-01

    Full Text Available Atmospheric trace gas measurements by cavity assisted long-path absorption spectroscopy are an emerging technology. An interesting approach is the combination of CEAS with broadband light sources, the broadband CEAS (BB-CEAS. BB-CEAS lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light path by the trace gas absorption, since cavity losses due to absorption by gases reduce the quality (Q of the cavity. In fact, at wavelength, where the quality of the BB-CEAS cavity is dominated by the trace gas absorption (especially at very high mirror reflectivity, the average light path will vary nearly inversely with the trace gas concentration and the strength of the band will become only weakly dependent on the trace gas concentration c in the cavity, (the differential optical density being proportional to the logarithm of the trace gas concentration. Only in the limiting case where the mirror reflectivity determines Q at all wavelength, the strength of the band as seen by the CE-DOAS instrument becomes directly proportional to the concentration c. We investigate these relationships in detail and present methods to correct for the cases between the two above extremes, which are of course the important ones in practice.

  17. Optimizing Broadband Terahertz Modulation with Hybrid Graphene/Metasurface Structures

    OpenAIRE

    Shi, S. -F.; Zeng, B.; Han, H. -L.; Hong, X; Tsai, H. -Z.; Jung, H. S.; Zettl, A.; Crommie, M. F.; Wang, F.

    2014-01-01

    We demonstrate efficient terahertz (THz) modulation by coupling graphene strongly with a broadband THz metasurface device. This THz metasurface, made of periodic gold slit arrays, shows near unity broadband transmission, which arises from coherent radiation of the enhanced local-field in the slits. Utilizing graphene as an active load with tunable conductivity, we can significantly modify the local-field enhancement and strongly modulate the THz wave transmission. This hybrid device also prov...

  18. Drivers of fixed and mobile broadband infrastructure adoption and quality

    OpenAIRE

    Tsai, Hsin-yi Sandy; Bauer, Johannes M.

    2014-01-01

    The benefits of advanced information and communication services are increasingly dependent on the quality of the available connectivity. This paper examines the factors that influence the quality of fixed and mobile broadband access in OECD countries. Drawing on institutional economics, the study provides an integrated conceptual framework that allows analyzing the interaction of supply, demand, policy, and contextual factors. We explore the drivers of broadband access and quality and potenti...

  19. A Performance Study of Wireless Broadband Access (WiMAX)

    OpenAIRE

    Maan A. S. Al-Adwany

    2011-01-01

    WiMAX (worldwide interoperability for microwave access) is one of the wireless broadband access technologies which supplies broadband services to clients, but it surpasses other technologies by its coverage area, where one base station can cover a small city. In this paper, WiMAX technology is studied by exploring its basic concepts, applications, and advantages / disadvantages. Also a MATLAB simulator is used to verify the operation of the WiMAX system under various chan...

  20. Efficiency of broadband internet adoption in European Union member states

    OpenAIRE

    Pavlyuk, Dmitry

    2011-01-01

    This paper is devoted to econometric analysis of broadband adoption efficiency in EU member states. Stochastic frontier models are widely used for efficiency estimation. We enhanced the stochastic frontier model by adding a spatial component into the model specification to reflect possible dependencies between neighbour countries. A maximum likelihood estimator for the model was developed. The proposed spatial autoregressive stochastic frontier model is used for estimation of broadband ad...

  1. Novel crystalline-waveguide broadband light sources for interferometry

    OpenAIRE

    Pollnau, Markus

    2003-01-01

    In recent years, broadband fiber interferometers have become very popular as basic instruments used in optical low-coherence reflectometry for diagnostics of fiber and integrated optics devices or in optical coherence tomography (OCT) for imaging applications in the biomedical field. The longitudinal resolution of such instruments is inversely proportional to the optical bandwidth of the light source. Broadband luminescence from transition-metal-ion doped materials can significantly improve t...

  2. Continuity check

    Energy Technology Data Exchange (ETDEWEB)

    Woof, M.

    2002-10-01

    This paper looks into both safety and technological developments in continuous mining. Manufacturers covered include Hydraphase, Eimco, Deilmann-Haniel, DBT and Joy. A recent Health and Safety Executive report mentioned three in incidents of frictional ignition of flammable gas by cutting equipment in a five year period to April 1999. 4 photos.

  3. Estimation of broadband surface emissivity from narrowband emissivities.

    Science.gov (United States)

    Tang, Bo-Hui; Wu, Hua; Li, Chuanrong; Li, Zhao-Liang

    2011-01-01

    This work analyzed and addressed the estimate of the broadband emissivities for the spectral domains 3-14μm (ε(3-14)) and 3-∞μm (ε(3-∞). Two linear narrow-to-broadband conversion models were proposed to estimate broadband emissivities ε(3-14) and ε(3-∞) using the Moderate Resolution Imaging Spectroradiometer (MODIS) derived emissivities in three thermal infrared channels 29 (8.4-8.7μm), 31 (10.78-11.28μm) and 32 (11.77-12.27μm). Two independent spectral libraries, the Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) spectral library and the MODIS UCSB (University of California, Santa Barbara) emissivity library, were used to calibrate and validate the proposed models. Comparisons of the estimated broadband emissivities using the proposed models and the calculated values from the spectral libraries, showed that the proposed method of estimation of broadband emissivity has potential accuracy and the Root Mean Square Error (RMSE) between estimated and calculated broadband emissivities is less than 0.01 for both ε(3-14) and ε(3-∞).

  4. Estimation of broadband surface emissivity from narrowband emissivities.

    Science.gov (United States)

    Tang, Bo-Hui; Wu, Hua; Li, Chuanrong; Li, Zhao-Liang

    2011-01-01

    This work analyzed and addressed the estimate of the broadband emissivities for the spectral domains 3-14μm (ε(3-14)) and 3-∞μm (ε(3-∞). Two linear narrow-to-broadband conversion models were proposed to estimate broadband emissivities ε(3-14) and ε(3-∞) using the Moderate Resolution Imaging Spectroradiometer (MODIS) derived emissivities in three thermal infrared channels 29 (8.4-8.7μm), 31 (10.78-11.28μm) and 32 (11.77-12.27μm). Two independent spectral libraries, the Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) spectral library and the MODIS UCSB (University of California, Santa Barbara) emissivity library, were used to calibrate and validate the proposed models. Comparisons of the estimated broadband emissivities using the proposed models and the calculated values from the spectral libraries, showed that the proposed method of estimation of broadband emissivity has potential accuracy and the Root Mean Square Error (RMSE) between estimated and calculated broadband emissivities is less than 0.01 for both ε(3-14) and ε(3-∞). PMID:21263556

  5. Developing a Broadband Adoption Model in the UK Context

    Science.gov (United States)

    Dwivedi, Yogesh K.; Mustafee, Navonil; Williams, Michael D.; Lal, Banita

    This research examines the factors affecting the consumer adoption of broadband in the United Kingdom. A conceptual model of broadband adoption was developed by selecting and justifying a number of relevant constructs from the technology adoption literature. The model was then empirically tested by employing survey data that was randomly collected from 358 UK broadband consumers. The findings suggest that, with the exception of one construct that was included in the conceptual model (namely, knowledge), all of the con structs significantly influence consumers when adopting broadband in a UK household. The significant constructs include relative advantage, utilitarian outcomes, hedonic outcomes, primary influence, facilitating conditions resources, and self-efficacy. Furthermore, when considering the behavioral intention and facilitating conditions resources constructs together, they significantly explain UK broad band adoption behavior. The theoretical contri bution of this research is that it determines and integrates the appropriate constructs from the technology adoption literature in order to enhance the knowledge of technology adoption from the consumer's perspective. This research has implications for policy makers and broadband providers since the results of this study can be exploited by the aforementioned stakeholders in order to encourage and promote the adoption and usage of broadband among the general population.

  6. Broadband metasurface absorber for solar thermal applications

    Science.gov (United States)

    Wan, C.; Chen, L.; Cryan, M. J.

    2015-12-01

    In this paper we propose a broadband polarization-independent selective absorber for solar thermal applications. It is based on a metal-dielectric-metal metasurface structure, but with an interlayer of absorbing amorphous carbon rather than a low loss dielectric. Optical absorbance results derived from finite difference time domain modelling are shown for ultra-thin carbon layers in air and on 200 nm of gold for a range of carbon thicknesses. A gold-amorphous carbon-gold trilayer with a top layer consisting of a 1D grating is then optimised in 2D to give a sharp transition from strong absorption up to 2 μm to strong reflection above 2 μm resulting in good solar selective performance. The gold was replaced by the high-melting-point metal tungsten, which is shown to have very similar performance to the gold case. 3D simulations then show that the gold-based structure performs well as a square periodic array of squares, however there is low absorption around 400 nm. A cross-based structure is found to increase this absorption without significantly reducing the performance at longer wavelengths.

  7. Hollow plasmonic antennas for broadband SERS spectroscopy.

    Science.gov (United States)

    Messina, Gabriele C; Malerba, Mario; Zilio, Pierfrancesco; Miele, Ermanno; Dipalo, Michele; Ferrara, Lorenzo; De Angelis, Francesco

    2015-01-01

    The chemical environment of cells is an extremely complex and multifaceted system that includes many types of proteins, lipids, nucleic acids and various other components. With the final aim of studying these components in detail, we have developed multiband plasmonic antennas, which are suitable for highly sensitive surface enhanced Raman spectroscopy (SERS) and are activated by a wide range of excitation wavelengths. The three-dimensional hollow nanoantennas were produced on an optical resist by a secondary electron lithography approach, generated by fast ion-beam milling on the polymer and then covered with silver in order to obtain plasmonic functionalities. The optical properties of these structures have been studied through finite element analysis simulations that demonstrated the presence of broadband absorption and multiband enhancement due to the unusual geometry of the antennas. The enhancement was confirmed by SERS measurements, which showed a large enhancement of the vibrational features both in the case of resonant excitation and out-of-resonance excitation. Such characteristics indicate that these structures are potential candidates for plasmonic enhancers in multifunctional opto-electronic biosensors.

  8. The Broadband Afterglow of GRB980703

    CERN Document Server

    Frail, D A; Berger, E; Harrison, F A; Sari, R; Kulkarni, S R; Taylor, G B; Bloom, J S; Fox, D W; Moriarty-Schieven, G H; Price, P A

    2003-01-01

    We present radio observations of the afterglow of the bright gamma-ray burst GRB980703 made between one day and one year after the burst. These data are combined with published late-time radio measurements and existing optical, near-infrared (NIR) and X-ray observations to create a comprehensive broadband dataset for modeling the physical parameters of the outflow. While a wind-stratified medium cannot be ruled out statistically, it requires a high fraction of the shock energy in the electrons, and so is not favored on theoretical grounds. Instead, the data are consistent with a fireball model in which the ejecta are collimated and expanding into a constant density medium. The radio data cannot be fit with an isotropic shock but instead require a jet break at ~ 3.5 days, not seen at optical wavelengths due to the presence of a a bright host galaxy. The addition of the full radio dataset constrains the self-absorption frequency, giving an estimate of the circumburst density of n ~ 30 cm^-3, a value which diffe...

  9. Broadband Observations of High Redshift Blazars

    CERN Document Server

    Paliya, Vaidehi S; Fabian, A C; Stalin, C S

    2016-01-01

    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 ($z=3.37$), CGRaBS J0225+1846 ($z=2.69$), BZQ J1430+4205 ($z=4.72$), and 3FGL J1656.2$-$3303 ($z=2.40$), using the quasi-simultaneous data from {\\it Swift}, {\\it NuSTAR}, and {\\it Fermi}-Large Area Telescope (LAT) and also the archival {\\it XMM-Newton} observations. Other than 3FGL J1656.2$-$3303, none of the sources were known as $\\gamma$-ray emitters and our analysis of $\\sim$7.5 years of LAT data reveals the first time detection of the statistically significant $\\gamma$-ray emission from CGRaBS J0225+1846. We generate the broadband spectral energy distributions (SED) of all the objects, centering at the epoch of {\\it NuSTAR} observations and reproduce them using a one zone leptonic emission model. The optical$-$UV emission in all the objects can be explained by the radiation from the accretion disk, whereas, X-ray to $\\gamma$-ray window of the SEDs are found to be dominated by the inverse Compton scattering off the broad line reg...

  10. Broadband Infrared Heterodyne Spectrometer: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, C G; Cunningham, C T; Tringe, J W

    2010-12-16

    This report summarizes the most important results of our effort to develop a new class of infrared spectrometers based on a novel broadband heterodyne design. Our results indicate that this approach could lead to a near-room temperature operation with performance limited only by quantum noise carried by the incoming signal. Using a model quantum-well infrared photodetector (QWIP), we demonstrated key performance features of our approach. For example, we directly measured the beat frequency signal generated by superimposing local oscillator (LO) light of one frequency and signal light of another through a spectrograph, by injecting the LO light at a laterally displaced input location. In parallel with the development of this novel spectrometer, we modeled a new approach to reducing detector volume though plasmonic resonance effects. Since dark current scales directly with detector volume, this ''photon compression'' can directly lead to lower currents. Our calculations indicate that dark current can be reduced by up to two orders of magnitude in an optimized ''superlens'' structure. Taken together, our spectrometer and dark current reduction strategies provide a promising path toward room temperature operation of a mid-wave and possibly long-wave infrared spectrometer.

  11. Impedance matching for broadband piezoelectric energy harvesting

    Science.gov (United States)

    Hagedorn, F.; Leicht, J.; Sanchez, D.; Hehn, T.; Manoli, Y.

    2013-12-01

    This paper presents a system design for broadband piezoelectric energy harvesting by means of impedance matching. An inductive load impedance is emulated by controlling the output current of the piezoelectric harvester with a bipolar boost converter. The reference current is derived from the low pass filtered voltage measured at the harvester terminals. In order to maximize the harvested power especially for nonresonant frequencies the filter parameters are adjusted by a simple optimization algorithm. However the amount of harvested power is limited by the efficiency of the bipolar boost converter. Therefore an additional switch in the bipolar boost converter is proposed to reduce the capacitive switching losses. The proposed system is simulated using numerical parameters of available discrete components. Using the additional switch, the harvested power is increased by 20%. The proposed system constantly harvests 80% of the theoretically available power over frequency. The usable frequency range of ±4Hz around the resonance frequency of the piezoelectric harvester is mainly limited due to the boost converter topology. This comparison does not include the power dissipation of the control circuit.

  12. Broadband Linear Polarization of Jupiter Trojans

    CERN Document Server

    Bagnulo, S; Stinson, A; Christou, A; Borisov, G B

    2016-01-01

    Trojan asteroids orbit in the Lagrange points of the system Sun-planet-asteroid. Their dynamical stability make their physical properties important proxies for the early evolution of our solar system. To study their origin, we want to characterize the surfaces of Jupiter Trojan asteroids and check possible similarities with objects of the main belt and of the Kuiper Belt. We have obtained high-accuracy broad-band linear polarization measurements of six Jupiter Trojans of the L4 population and tried to estimate the main features of their polarimetric behaviour. We have compared the polarimetric properties of our targets among themselves, and with those of other atmosphere-less bodies of our solar system. Our sample show approximately homogeneous polarimetric behaviour, although some distinct features are found between them. In general, the polarimetric properties of Trojan asteroids are similar to those of D- and P-type main-belt asteroids. No sign of coma activity is detected in any of the observed objects. A...

  13. Broadband Acoustic Cloak for Ultrasound Waves

    CERN Document Server

    Zhang, Shu; Fang, Nicholas

    2010-01-01

    Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Due to the non-resonant nature of the building elements, this low loss (~6dB/m) cylindrical cloak exhibits excellent invisibility over a broad frequency range from 52 to 64 kHz in the measurements. The low visibility of the cloaked object for underwater ultrasound shed a light on the fundamental understanding of ma...

  14. Ultra-broadband THz time-domain spectroscopy of common polymers using THz air photonics

    DEFF Research Database (Denmark)

    D’Angelo, Francesco; Mics, Zoltán; Bonn, Mischa;

    2014-01-01

    -domain spectrometer employing air-photonics for the generation and detection of single-cycle sub-50 fs THz transients. The time domain measurements provide direct access to both the absorption and refractive index spectra. The polymers LDPE and TOPAS® demonstrate negligible absorption and spectrally-flat refractive...... index across the entire spectroscopy window, revealing the high potential of these polymers for applications in THz photonics such as ultra-broadband polymer-based dielectric mirrors, waveguides, and fibers. Resonant high-frequency polar vibrational modes are observed and assigned in polymers PA6...... and PTFE, and their dielectric functions in the complete frequency window 2-15 THz are theoretically reproduced. Our results demonstrate the potential of ultrabroadband air-photonics-based THz time domain spectroscopy as a valuable analytic tool for materials science....

  15. Identification of damage in a suspension component using narrowband and broadband nonlinear signal processing techniques

    Science.gov (United States)

    Haroon, Muhammad; Adams, Douglas E.

    2007-04-01

    Fatigue tests on a stabilizer bar link of an automotive suspension system are used to initiate a crack and grow the crack size. During these tests, slow sine sweeps are used to extract narrowband restoring forces across the stabilizer bar link. The restoring forces are shown to characterize the nonlinear changes in component internal forces due to crack growth. Broadband frequency response domain techniques are used to analyze the durability response data. Nonlinear frequency domain models of the dynamic transmissibility across the cracked region are shown to change as a function of crack growth. Higher order spectra are used to show the increase in nonlinear coupling of response frequency components with the appearance and growth of the crack. It is shown that crack growth can be detected and characterized by the changes in nonlinear indicators.

  16. Broadband CARS spectral phase retrieval using a time-domain Kramers-Kronig transform.

    Science.gov (United States)

    Liu, Yuexin; Lee, Young Jong; Cicerone, Marcus T

    2009-05-01

    We describe a closed-form approach for performing a Kramers-Kronig (KK) transform that can be used to rapidly and reliably retrieve the phase, and thus the resonant imaginary component, from a broadband coherent anti-Stokes Raman scattering (CARS) spectrum with a nonflat background. In this approach we transform the frequency-domain data to the time domain, perform an operation that ensures a causality criterion is met, then transform back to the frequency domain. The fact that this method handles causality in the time domain allows us to conveniently account for spectrally varying nonresonant background from CARS as a response function with a finite rise time. A phase error accompanies KK transform of data with finite frequency range. In examples shown here, that phase error leads to small (<1%) errors in the retrieved resonant spectra.

  17. Contemporaneous Broadband Observations of Three High-Redshift BL Lac Objects

    OpenAIRE

    Ackermann, Markus; Ajello, M.; J. Bregeon(c); Troja, E.; G. Vianello; Wood, K. S.; Wood, M; Fermi-LAT Collaboration; Britto, R. J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.

    2016-01-01

    We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects 3FGL J0022.1−1855 (z = 0.689), 3FGL J0630.9−2406 ($z\\quad \\gtrsim $ 1.239), and 3FGL J0811.2−7529 (z = 0.774), detected by Fermi with relatively flat gigaelectronvolt spectra. By observing simultaneously in the near-infrared to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the r...

  18. An Integrated Model for the Production of X-Ray Time Lags and Quiescent Spectra from Homogeneous and Inhomogeneous Black Hole Accretion Coronae

    Science.gov (United States)

    Kroon, John J.; Becker, Peter A.

    2016-04-01

    Many accreting black holes manifest time lags during outbursts, in which the hard Fourier component typically lags behind the soft component. Despite decades of observations of this phenomenon, the underlying physical explanation for the time lags has remained elusive, although there are suggestions that Compton reverberation plays an important role. However, the lack of analytical solutions has hindered the interpretation of the available data. In this paper, we investigate the generation of X-ray time lags in Compton scattering coronae using a new mathematical approach based on analysis of the Fourier-transformed transport equation. By solving this equation, we obtain the Fourier transform of the radiation Green’s function, which allows us to calculate the exact dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous coronal clouds. We use the new formalism to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photon injection. We show that our model can successfully reproduce both the observed time lags and the time-averaged (quiescent) X-ray spectra for Cyg X-1 and GX 339-04, using a single set of coronal parameters for each source. The time lags are the result of impulsive bremsstrahlung injection occurring near the outer edge of the corona, while the time-averaged spectra are the result of continual distributed injection of soft photons throughout the cloud.

  19. AN INTEGRATED MODEL FOR THE PRODUCTION OF X-RAY TIME LAGS AND QUIESCENT SPECTRA FROM HOMOGENEOUS AND INHOMOGENEOUS BLACK HOLE ACCRETION CORONAE

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, John J.; Becker, Peter A., E-mail: jkroon@gmu.edu, E-mail: pbecker@gmu.edu [Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030-4444 (United States)

    2016-04-20

    Many accreting black holes manifest time lags during outbursts, in which the hard Fourier component typically lags behind the soft component. Despite decades of observations of this phenomenon, the underlying physical explanation for the time lags has remained elusive, although there are suggestions that Compton reverberation plays an important role. However, the lack of analytical solutions has hindered the interpretation of the available data. In this paper, we investigate the generation of X-ray time lags in Compton scattering coronae using a new mathematical approach based on analysis of the Fourier-transformed transport equation. By solving this equation, we obtain the Fourier transform of the radiation Green’s function, which allows us to calculate the exact dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous coronal clouds. We use the new formalism to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photon injection. We show that our model can successfully reproduce both the observed time lags and the time-averaged (quiescent) X-ray spectra for Cyg X-1 and GX 339-04, using a single set of coronal parameters for each source. The time lags are the result of impulsive bremsstrahlung injection occurring near the outer edge of the corona, while the time-averaged spectra are the result of continual distributed injection of soft photons throughout the cloud.

  20. Continuation calculus

    Directory of Open Access Journals (Sweden)

    Bram Geron

    2013-09-01

    Full Text Available Programs with control are usually modeled using lambda calculus extended with control operators. Instead of modifying lambda calculus, we consider a different model of computation. We introduce continuation calculus, or CC, a deterministic model of computation that is evaluated using only head reduction, and argue that it is suitable for modeling programs with control. It is demonstrated how to define programs, specify them, and prove them correct. This is shown in detail by presenting in CC a list multiplication program that prematurely returns when it encounters a zero. The correctness proof includes termination of the program. In continuation calculus we can model both call-by-name and call-by-value. In addition, call-by-name functions can be applied to call-by-value results, and conversely.

  1. Magnetic-resonance-imaging-coupled broadband near-infrared tomography system for small animal brain studies

    Science.gov (United States)

    Xu, Heng; Springett, Roger; Dehghani, Hamid; Pogue, Brian W.; Paulsen, Keith D.; Dunn, Jeff F.

    2005-04-01

    A novel magnetic-resonance-coupled broadband near-infrared (NIR) tomography system for small animal brain studies is described. Several features of the image formation approach are new in NIR tomography and represent major advances in the path to recovering high-resolution hemoglobin and oxygen saturation images of tissue. The NIR data were broadband and continuous wave and were used along with a second-derivative-based estimation of the path length from water absorption. The path length estimation from water was then used along with the attenuation spectrum to recover absorption and reduced scattering coefficient images at multiple wavelengths and then to recover images of total hemoglobin and oxygen saturation. Going beyond these basics of NIR tomography, software has been developed to allow inclusion of structures derived from MR imaging (MRI) for the external and internal tissue boundaries, thereby improving the accuracy and spatial resolution of the properties in each tissue type. The system has been validated in both tissue-simulating phantoms, with 10% accuracy observed, and in a rat cranium imaging experiment. The latter experiment used variation in inspired oxygen (FiO2) to vary the observed hemoglobin and oxygen saturation images. Quantitative agreement was observed between the changes in deoxyhemoglobin values derived from NIR and the changes predicted with blood-oxygen-level-dependent (BOLD) MRI. This system represents the initial stage in what will likely be a larger role for NIR tomography, coupled to MRI, and illustrates that the technological challenges of using continuous-wave broadband data and inclusion of a priori structural information can be met with careful phantom studies.

  2. Theoretical realization of robust broadband transparency in ultrathin seamless nanostructures by dual blackbodies for near infrared light

    Science.gov (United States)

    Zhang, Lei; Hao, Jiaming; Ye, Huapeng; Yeo, Swee Ping; Qiu, Min; Zouhdi, Said; Qiu, Cheng-Wei

    2013-03-01

    varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure (in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc. Electronic supplementary information (ESI) available: Comparison of transmittance spectra between structures with and without Ag film at the middle. Transmittance spectra of structures with different thicknesses of Ag film. See DOI: 10.1039/c3nr34278f

  3. Wideband Dynamic Radio Spectra of Two Ultra-cool dwarfs

    OpenAIRE

    Lynch, C.; Mutel, R. L.; Gudel, M.

    2014-01-01

    A number of radio-loud ultra cool dwarf stars (UCD) exhibit both continuous broadband and highly polarized pulsed radio emission. In order to determine the nature of the emission and the physical characteristics in the source region, we have made multi-epoch, wideband spectral observations of TVLM 0513-46 and 2M 0746+20. We combine these observations with archival radio data to fully characterize both the temporal and spectral properties of the radio emission. The continuum spectral energy di...

  4. A graphene-based broadband optical modulator

    Science.gov (United States)

    Liu, Ming; Yin, Xiaobo; Ulin-Avila, Erick; Geng, Baisong; Zentgraf, Thomas; Ju, Long; Wang, Feng; Zhang, Xiang

    2011-06-01

    Integrated optical modulators with high modulation speed, small footprint and large optical bandwidth are poised to be the enabling devices for on-chip optical interconnects. Semiconductor modulators have therefore been heavily researched over the past few years. However, the device footprint of silicon-based modulators is of the order of millimetres, owing to its weak electro-optical properties. Germanium and compound semiconductors, on the other hand, face the major challenge of integration with existing silicon electronics and photonics platforms. Integrating silicon modulators with high-quality-factor optical resonators increases the modulation strength, but these devices suffer from intrinsic narrow bandwidth and require sophisticated optical design; they also have stringent fabrication requirements and limited temperature tolerances. Finding a complementary metal-oxide-semiconductor (CMOS)-compatible material with adequate modulation speed and strength has therefore become a task of not only scientific interest, but also industrial importance. Here we experimentally demonstrate a broadband, high-speed, waveguide-integrated electroabsorption modulator based on monolayer graphene. By electrically tuning the Fermi level of the graphene sheet, we demonstrate modulation of the guided light at frequencies over 1GHz, together with a broad operation spectrum that ranges from 1.35 to 1.6µm under ambient conditions. The high modulation efficiency of graphene results in an active device area of merely 25µm2, which is among the smallest to date. This graphene-based optical modulation mechanism, with combined advantages of compact footprint, low operation voltage and ultrafast modulation speed across a broad range of wavelengths, can enable novel architectures for on-chip optical communications.

  5. Computing broadband accelerograms using kinematic rupture modeling

    International Nuclear Information System (INIS)

    In order to make the broadband kinematic rupture modeling more realistic with respect to dynamic modeling, physical constraints are added to the rupture parameters. To improve the slip velocity function (SVF) modeling, an evolution of the k-2 source model is proposed, which consists to decompose the slip as a sum of sub-events by band of k. This model yields to SVF close to the solution proposed by Kostrov for a crack, while preserving the spectral characteristics of the radiated wave field, i.e. a w2 model with spectral amplitudes at high frequency scaled to the coefficient of directivity Cd. To better control the directivity effects, a composite source description is combined with a scaling law defining the extent of the nucleation area for each sub-event. The resulting model allows to reduce the apparent coefficient of directivity to a fraction of Cd, as well as to reproduce the standard deviation of the new empirical attenuation relationships proposed for Japan. To make source models more realistic, a variable rupture velocity in agreement with the physics of the rupture must be considered. The followed approach that is based on an analytical relation between the fracture energy, the slip and the rupture velocity, leads to higher values of the peak ground acceleration in the vicinity of the fault. Finally, to better account for the interaction of the wave field with the geological medium, a semi-empirical methodology is developed combining a composite source model with empirical Green functions, and is applied to the Yamaguchi, Mw 5.9 earthquake. The modeled synthetics reproduce satisfactorily well the observed main characteristics of ground motions. (author)

  6. The Representation of a Broadband Vector Field

    Institute of Scientific and Technical Information of China (English)

    Qunyan Ren; Jean Pierre Hermand; Shengchun Piao

    2011-01-01

    Compared to a scalar pressure sensor,a vector sensor can provide a higher signal-to-noise ratio (SNR)signal and more detailed information on the sound field.Study on vector sensors and their applications have become a hot topic.Research on the representation of a vector field is highly relevant for extending the scope of vector sensor technology.This paper discusses the range-frequency distribution of the vector field due to a broadband acoustic source moving in a shallow-water waveguide as the self noise of a surface ship,and the vector extension of the waveguide impulse response measured over a limited frequency range using an active source of known waveform.From theory analysis and numerical simulation,the range-frequency representation of a vector field exhibits an interference structure qualitatively similar to that of the corresponding pressure field but,being quantitatively different,provides additional information on the waveguide,especially through the vertical component.For the range-frequency representation,physical quantities that can better exhibit the interference characteristics of the waveguide are the products of pressure and particle velocity and of the pressure and pressure gradient.An image processing method to effectively detect and isolate the individual striations from an interference structure was reviewed briefly.The representation of the vector impulse response was discussed according to two different measurement systems,also known as particle velocity and pressure gradient.The vector impulse response representation can not only provide additional information from pressure only but even more than that of the range-frequency representation.

  7. Iron line profiles in Suzaku spectra of bare Seyfert galaxies

    CERN Document Server

    Patrick, A R; Porquet, D; Markowitz, A G; Lobban, A P; Terashima, Y

    2010-01-01

    We methodically model the broad-band Suzaku spectra of a small sample of six 'bare' Seyfert galaxies: Ark 120, Fairall 9, MCG-02-14-009, Mrk 335, NGC 7469 and SWIFT J2127.4+5654. The analysis of bare Seyferts allows a consistent and physical modelling of AGN due to a weak amount of any intrinsic warm absorption, removing the degeneracy between the spectral curvature due to warm absorption and the red-wing of the Fe K region. Through effective modelling of the broad-band spectrum and investigating the presence of narrow neutral or ionized emission lines and reflection from distant material, we obtain an accurate and detailed description of the Fe K line region using models such as laor, kerrdisk and kerrconv. Results suggest that ionized emission lines at 6.7 keV and 6.97 keV (particularly Fe XXVI) are relatively common and the inclusion of these lines can greatly affect the parameters obtained with relativistic models i.e. spin, emissivity, inner radius of emission and inclination. Moderately broad components...

  8. Non-Gaussian Spectra

    CERN Document Server

    Ferreira, P G; Ferreira, Pedro G.; Magueijo, Joao

    1997-01-01

    Gaussian cosmic microwave background skies are fully specified by the power spectrum. The conventional method of characterizing non-Gaussian skies is to evaluate higher order moments, the n-point functions and their Fourier transforms. We argue that this method is inefficient, due to the redundancy of information existing in the complete set of moments. In this paper we propose a set of new statistics or non-Gaussian spectra to be extracted out of the angular distribution of the Fourier transform of the temperature anisotropies in the small field limit. These statistics complement the power spectrum and act as localization, shape, and connectedness statistics. They quantify generic non-Gaussian structure, and may be used in more general image processing tasks. We concentrate on a subset of these statistics and argue that while they carry no information in Gaussian theories they may be the best arena for making predictions in some non-Gaussian theories. As examples of applications we consider superposed Gaussi...

  9. Modelling and Evaluation of Spectra in Beam Aided Spectroscopy

    Science.gov (United States)

    von Hellermann, M. G.; Delabie, E.; Jaspers, R.; Lotte, P.; Summers, H. P.

    2008-10-01

    The evaluation of active beam induced spectra requires advanced modelling of both active and passive features. Three types of line shapes are addressed in this paper: Thermal spectra representing Maxwellian distribution functions described by Gaussian-like line shapes, secondly broad-band fast ion spectra with energies well above local ion temperatures, and, finally, the narrow lines shapes of the equi-spaced Motion Stark multiplet (MSE) of excited neutral beam particles travelling through the magnetic field confining the plasma. In each case additional line shape broadening caused by Gaussian-like instrument functions is taken into account. Further broadening effects are induced by collision velocity dependent effective atomic rates where the observed spectral shape is the result of a convolution of emission rate function and velocity distribution function projected into the direction of observation. In the case of Beam Emission Spectroscopy which encompasses the Motional Stark features, line broadening is also caused by the finite angular spread of injected neutrals and secondly by a ripple in the acceleration voltage associated with high energy neutral beams.

  10. Average electric wave spectra across the plasma sheet and their relation to ion bulk speed

    Science.gov (United States)

    Baumjohann, W.; Treumann, R. A.; Labelle, J.; Anderson, R. R.

    1989-01-01

    Using 4 months of tail data obtained by the ELF/MF spectrum analyzer of the wave experiment and the three-dimensional plasma instrument on board the AMPTE/IRM satellite, a statistical survey on the electric wave spectral density in the earth's plasma sheet has been conducted. More than 50,000 10-s-averaged electric wave spectra were analyzed with respect to differences between their values in the inner and outer central plasma sheet and the plasma sheet boundary layer as well as their dependence on radial distance and ion bulk speed. High-speed flows are dominated by broadband electrostatic noise with highest spectral densities in the plasma sheet boundary, where broadband electrostatic noise also exists during periods of low-speed flows. The broadband electrostatic noise has a typical spectral index of about -2. During low-speed flows the spectra in the central plasma sheet show distinct emissions at the electron cyclotron odd half-harmonic and upper hybrid frequency. Wave intensities during episodes of fast perpendicular flows are higher than those associated with fast parallel flows.

  11. Quantitative broadband absorption and scattering spectroscopy in turbid media by combined frequency-domain and steady state methodologies

    Science.gov (United States)

    Tromberg, Bruce J.; Berger, Andrew J.; Cerussi, Albert E.; Bevilacqua, Frederic; Jakubowski, Dorota

    2008-09-23

    A technique for measuring broadband near-infrared absorption spectra of turbid media that uses a combination of frequency-domain and steady-state reflectance methods. Most of the wavelength coverage is provided by a white-light steady-state measurement, whereas the frequency-domain data are acquired at a few selected wavelengths. Coefficients of absorption and reduced scattering derived from the frequency-domain data are used to calibrate the intensity of the steady-state measurements and to determine the reduced scattering coefficient at all wavelengths in the spectral window of interest. The absorption coefficient spectrum is determined by comparing the steady-state reflectance values with the predictions of diffusion theory, wavelength by wavelength. Absorption spectra of a turbid phantom and of human breast tissue in vivo, derived with the combined frequency-domain and steady-state technique, agree well with expected reference values.

  12. Physical meaning of conductivity spectra for ZnO ceramics

    Institute of Scientific and Technical Information of China (English)

    Cheng Peng-Fei; Li Sheng-Tao; Li Jian-Ying; Ding Can; Yang Yan

    2012-01-01

    With the help of broadband dielectric spectroscopy in a wide temperature and frequency range,the conductivity spectra of ZnO polycrystalline ceramics are measured and the direct-current-like (DC-like) conductivity and relaxation polarization conductivity are observed successively along the frequency axis.According to the classical Debye theory and Cole-Cole equation,the physical meanings of the two conductivities are discussed.It is found that the DC-like conductivity corresponds to electron transportation over the Schottky barrier at the grainboundary.The relaxation polarization conductivity corresponds to electronic trap relaxation of intrinsic point defects (zinc interstitial and oxygen vacancy).When in the high frequency region,the relaxation conductivity obeys the universal law with the index n equal to the index α in the Cole-Cole equation as an indictor of disorder degree.

  13. Spatial-temporal dynamics of broadband terahertz Bessel beam propagation

    Science.gov (United States)

    Semenova, V. A.; Kulya, M. S.; Bespalov, V. G.

    2016-08-01

    The unique properties of narrowband and broadband terahertz Bessel beams have led to a number of their applications in different fields, for example, for the depth of focusing and resolution enhancement in terahertz imaging. However, broadband terahertz Bessel beams can probably be also used for the diffraction minimization in the short-range broadband terahertz communications. For this purpose, the study of spatial-temporal dynamics of the broadband terahertz Bessel beams is needed. Here we present a simulation-based study of the propagating in non-dispersive medium broadband Bessel beams generated by a conical axicon lens. The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the Bessel beam in the frequency range from 0.1 to 3 THz at the distances 10-200 mm from the axicon. Bessel beam field is studied for the different spectral components of the initial pulse. The simulation results show that for the given parameters of the axicon lens one can obtain the Gauss-Bessel beam generation in the spectral range from 0.1 to 3 THz. The length of non-diffraction propagation for a different spectral components was measured, and it was shown that for all spectral components of the initial pulse this length is about 130 mm.

  14. Negative impedance shunted electromagnetic absorber for broadband absorbing: experimental investigation

    International Nuclear Information System (INIS)

    The traditional tuned mass absorber is widely employed to control the vibration of a primary structure by transferring the vibrating energy to the absorber. However, the working band of the absorber is very narrow, which limits the application of broadband vibration control. This study presents a novel broadband electromagnetic absorber by first introducing two negative impedance shunts to improve broadband damping of the absorber. The electromagnetic absorber is modeled, and the corresponding electromagnetic coupling coefficient is tested. A cantilever beam is employed to verify the broadband vibration absorption of the negative resistance (NR) shunted electromagnetic absorber (NR absorber) and the negative inductance NR shunted electromagnetic absorber (NINR absorber). The governing equations of the beam with two absorbers are derived, and the experiments are set up. The results point out that the NR and NINR absorbers can attenuate the broadband vibration. The proposed absorbers do not need the feedback system and the real-time controller compared to the active absorber; hence, they have great application potential in aerospace and in submarine applications, as well as in civil and mechanical engineering. (paper)

  15. Broadband anti-reflective and water-repellent coatings on glass substrates for self-cleaning photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaoyu [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, Zhongguancun Donglu 29, Haidianqu, Beijing 100190 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); He, Junhui, E-mail: jhhe@mail.ipc.ac.cn [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences, Zhongguancun Donglu 29, Haidianqu, Beijing 100190 (China); Liu, Weiyi [Institute of Optoelectronics, Nankai University, Tianjin 300071 (China)

    2013-07-15

    Graphical abstract: High performance broadband antireflective and water-repellent coatings were fabricated on glass substrates, which can improve the short-circuit current of solar cells as much as 6.6% in comparison with glass substrates without the coatings. - Highlights: • Broadband anti-reflective and water-repellent coatings were fabricated. • Transmittance increased to 99.0%, significantly higher than that of commercial solar glasses. • The performance of standard solar cells with the AR coating was enhanced as much as 6.6%. - Abstract: High performance broadband antireflective (AR) and water-repellent coatings were fabricated on glass substrates by assembly of silica nanoparticles and polyelectrolytes via the layer-by-layer (LbL) assembly technique, followed by calcination and hydrophobic modification. A porous poly(diallyladimethylammonium chloride) (PDDA)/20 nm SiO{sub 2} nanoparticles (S-20) multilayer coating with AR property was prepared first. The maximum transmittance is as high as 99.0%, while that of the glass substrate is only 91.3%. After calcination and hydrophobic modification, the coating became water-repellent while maintaining the good AR property. Such water-repellent AR coatings can improve the short-circuit current of solar cells as much as 6.6% in comparison with glass substrates without the coatings. Scanning electron microscopy (SEM) was used to observe the morphology and thickness of coatings. Transmission spectra and reflection spectra were characterized by UV–vis spectrophotometer. The surface wettability was studied by a contact angle/interface system.

  16. Broadband radio spectral observations of the solar eclipse on 2008-08-01 and its implications on the quiet Sun atmospheric model

    Institute of Scientific and Technical Information of China (English)

    TAN BaoLin; CHEN LinJie; JI GuoShu; YAN YiHua; ZHANG Yin; TAN ChengMin; HUANG Jing; LIU YuYing; FU QiJun; CHEN ZhiJun; LIU Fei

    2009-01-01

    Based on the joint-observations of the radio broadband spectral emissions of the solar eclipse on Au-gust 1, 2008 at Jiuquan (total eclipse) and Huairou (partial eclipse) at the frequencies of 2.00-5.60 GHz (Jiuquan), 2.60-3.80 GHz (Chinese solar broadband radiospectrometer, SBRS/Huairou), and 5.20-7.60 GHz (SBRS/Huairou), the authors assemble a successive series of broadband spectra with a frequency of 2.60-7.60 GHz to observe the solar eclipse synchronously. This is the first attempt to analyze the solar eclipse radio emission under the two telescopes located at different places with broadband frequencies in the periods of total and partial eclipses. With these analyses, the authors made a semiempirical model of the coronal plasma density of the quiet Sun, which can be expressed as n_e≌1.42×10~9(r~(-2)+1.93r~(-5)) (cm~(-3)), in the space range of r=1.039-1.212 R_⊙, and made a comparison with the classic model.

  17. Hybrid Broadband Ground-Motion Simulations: Combining Long-Period Deterministic Synthetics with High-Frequency Multiple S-to-S Backscattering

    KAUST Repository

    Mai, Paul Martin

    2010-09-20

    We present a new approach for computing broadband (0-10 Hz) synthetic seismograms by combining high-frequency (HF) scattering with low-frequency (LF) deterministic seismograms, considering finite-fault earthquake rupture models embedded in 3D earth structure. Site-specific HF-scattering Green\\'s functions for a heterogeneous medium with uniformly distributed random isotropic scatterers are convolved with a source-time function that characterizes the temporal evolution of the rupture process. These scatterograms are then reconciled with the LF-deterministic waveforms using a frequency-domain optimization to match both amplitude and phase spectra around the target intersection frequency. The scattering parameters of the medium, scattering attenuation ηs, intrinsic attenuation ηi, and site-kappa, as well as frequency-dependent attenuation, determine waveform and spectral character of the HF-synthetics and thus affect the hybrid broadband seismograms. Applying our methodology to the 1994 Northridge earthquake and validating against near-field recordings at 24 sites, we find that our technique provides realistic broadband waveforms and consistently reproduces LF ground-motion intensities for two independent source descriptions. The least biased results, compared to recorded strong-motion data, are obtained after applying a frequency-dependent site-amplification factor to the broadband simulations. This innovative hybrid ground-motion simulation approach, applicable to any arbitrarily complex earthquake source model, is well suited for seismic hazard analysis and ground-motion estimation.

  18. Broadband Observations of High Redshift Blazars

    Science.gov (United States)

    Paliya, Vaidehi S.; Parker, M. L.; Fabian, A. C.; Stalin, C. S.

    2016-07-01

    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 (z = 3.37), CGRaBS J0225+1846 (z = 2.69), BZQ J1430+4205 (z = 4.72), and 3FGL J1656.2‑3303 (z = 2.40) using quasi-simultaneous data from the Swift, Nuclear Spectroscopic Telescope Array (NuSTAR) and the Fermi-Large Area Telescope (LAT) and also archival XMM-Newton observations. Other than 3FGL J1656.2‑3303, none of the sources were known as γ-ray emitters, and our analysis of ∼7.5 yr of LAT data reveals the first time detection of statistically significant γ-ray emission from CGRaBS J0225+1846. We generate the broadband spectral energy distributions (SED) of all the objects, centering at the epoch of NuSTAR observations and reproduce them using a one-zone leptonic emission model. The optical‑UV emission in all the objects can be explained by radiation from the accretion disk, whereas the X-ray to γ-ray windows of the SEDs are found to be dominated by inverse Compton scattering off the broad line region photons. All of them host black holes that are billions of solar masses. Comparing the accretion disk luminosity and the jet power of these sources with a large sample of blazars, we find them to occupy a high disk luminosity–jet power regime. We also investigate the X-ray spectral properties of the sources in detail with a major focus on studying the causes of soft X-ray deficit, a feature generally seen in high redshift radio-loud quasars. We summarize that this feature could be explained based on the intrinsic curvature in the jet emission rather than being due to the external effects predicted in earlier studies, such as host galaxy and/or warm absorption.

  19. On the phenomenological classification of continuum radio spectra variability patterns of Fermi blazars

    CERN Document Server

    Angelakis, E; Nestoras, I; Fromm, C M; Schmidt, R; Zensus, J A; Marchili, N; Krichbaum, T P; Perucho-Pla, M; Ungerechts, H; Sievers, A; Riquelme, D

    2011-01-01

    The F-GAMMA program is a coordinated effort to investigate the physics of Active Galactic Nuclei (AGNs) via multi-frequency monitoring of {\\em Fermi} blazars. The current study is concerned with the broad-band radio spectra composed of measurement at ten frequencies between 2.64 and 142 GHz. It is shown that any of the 78 sources studied can be classified in terms of their variability characteristics in merely 5 types of variability. The first four types are dominated by spectral evolution and can be reproduced by a simple two-component system made of the quiescent spectrum of a large scale jet populated with a flaring event evolving according to Marscher & Gear (1985). The last type is characterized by an achromatic change of the broad-band spectrum which must be attributed to a completely different mechanism. Here are presented, the classification, the assumed physical system and the results of simulations that have been conducted.

  20. Hyperbolic-cosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy. II. Broadband characterization.

    Science.gov (United States)

    Sidabras, Jason W; Strangeway, Robert A; Mett, Richard R; Anderson, James R; Mainali, Laxman; Hyde, James S

    2016-03-01

    Experimental results have been reported on an oversize rectangular waveguide assembly operating nominally at 94 GHz. It was formed using commercially available WR28 waveguide as well as a pair of specially designed tapers with a hyperbolic-cosine shape from WR28 to WR10 waveguide [R. R. Mett et al., Rev. Sci. Instrum. 82, 074704 (2011)]. The oversize section reduces broadband insertion loss for an Electron Paramagnetic Resonance (EPR) probe placed in a 3.36 T magnet. Hyperbolic-cosine tapers minimize reflection of the main mode and the excitation of unwanted propagating waveguide modes. Oversize waveguide is distinguished from corrugated waveguide, overmoded waveguide, or quasi-optic techniques by minimal coupling to higher-order modes. Only the TE10 mode of the parent WR10 waveguide is propagated. In the present work, a new oversize assembly with a gradual 90° twist was implemented. Microwave power measurements show that the twisted oversize waveguide assembly reduces the power loss in the observe and pump arms of a W-band bridge by an average of 2.35 dB and 2.41 dB, respectively, over a measured 1.25 GHz bandwidth relative to a straight length of WR10 waveguide. Network analyzer measurements confirm a decrease in insertion loss of 2.37 dB over a 4 GHz bandwidth and show minimal amplitude distortion of approximately 0.15 dB. Continuous wave EPR experiments confirm these results. The measured phase variations of the twisted oversize waveguide assembly, relative to an ideal distortionless transmission line, are reduced by a factor of two compared to a straight length of WR10 waveguide. Oversize waveguide with proper transitions is demonstrated as an effective way to increase incident power and the return signal for broadband EPR experiments. Detailed performance characteristics, including continuous wave experiment using 1 μM 2,2,6,6-tetramethylpiperidine-1-oxyl in aqueous solution, provided here serve as a benchmark for other broadband low-loss probes in

  1. Hyperbolic-cosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy. II. Broadband characterization.

    Science.gov (United States)

    Sidabras, Jason W; Strangeway, Robert A; Mett, Richard R; Anderson, James R; Mainali, Laxman; Hyde, James S

    2016-03-01

    Experimental results have been reported on an oversize rectangular waveguide assembly operating nominally at 94 GHz. It was formed using commercially available WR28 waveguide as well as a pair of specially designed tapers with a hyperbolic-cosine shape from WR28 to WR10 waveguide [R. R. Mett et al., Rev. Sci. Instrum. 82, 074704 (2011)]. The oversize section reduces broadband insertion loss for an Electron Paramagnetic Resonance (EPR) probe placed in a 3.36 T magnet. Hyperbolic-cosine tapers minimize reflection of the main mode and the excitation of unwanted propagating waveguide modes. Oversize waveguide is distinguished from corrugated waveguide, overmoded waveguide, or quasi-optic techniques by minimal coupling to higher-order modes. Only the TE10 mode of the parent WR10 waveguide is propagated. In the present work, a new oversize assembly with a gradual 90° twist was implemented. Microwave power measurements show that the twisted oversize waveguide assembly reduces the power loss in the observe and pump arms of a W-band bridge by an average of 2.35 dB and 2.41 dB, respectively, over a measured 1.25 GHz bandwidth relative to a straight length of WR10 waveguide. Network analyzer measurements confirm a decrease in insertion loss of 2.37 dB over a 4 GHz bandwidth and show minimal amplitude distortion of approximately 0.15 dB. Continuous wave EPR experiments confirm these results. The measured phase variations of the twisted oversize waveguide assembly, relative to an ideal distortionless transmission line, are reduced by a factor of two compared to a straight length of WR10 waveguide. Oversize waveguide with proper transitions is demonstrated as an effective way to increase incident power and the return signal for broadband EPR experiments. Detailed performance characteristics, including continuous wave experiment using 1 μM 2,2,6,6-tetramethylpiperidine-1-oxyl in aqueous solution, provided here serve as a benchmark for other broadband low-loss probes in

  2. Hyperbolic-cosine waveguide tapers and oversize rectangular waveguide for reduced broadband insertion loss in W-band electron paramagnetic resonance spectroscopy. II. Broadband characterization

    Science.gov (United States)

    Sidabras, Jason W.; Strangeway, Robert A.; Mett, Richard R.; Anderson, James R.; Mainali, Laxman; Hyde, James S.

    2016-03-01

    Experimental results have been reported on an oversize rectangular waveguide assembly operating nominally at 94 GHz. It was formed using commercially available WR28 waveguide as well as a pair of specially designed tapers with a hyperbolic-cosine shape from WR28 to WR10 waveguide [R. R. Mett et al., Rev. Sci. Instrum. 82, 074704 (2011)]. The oversize section reduces broadband insertion loss for an Electron Paramagnetic Resonance (EPR) probe placed in a 3.36 T magnet. Hyperbolic-cosine tapers minimize reflection of the main mode and the excitation of unwanted propagating waveguide modes. Oversize waveguide is distinguished from corrugated waveguide, overmoded waveguide, or quasi-optic techniques by minimal coupling to higher-order modes. Only the TE10 mode of the parent WR10 waveguide is propagated. In the present work, a new oversize assembly with a gradual 90° twist was implemented. Microwave power measurements show that the twisted oversize waveguide assembly reduces the power loss in the observe and pump arms of a W-band bridge by an average of 2.35 dB and 2.41 dB, respectively, over a measured 1.25 GHz bandwidth relative to a straight length of WR10 waveguide. Network analyzer measurements confirm a decrease in insertion loss of 2.37 dB over a 4 GHz bandwidth and show minimal amplitude distortion of approximately 0.15 dB. Continuous wave EPR experiments confirm these results. The measured phase variations of the twisted oversize waveguide assembly, relative to an ideal distortionless transmission line, are reduced by a factor of two compared to a straight length of WR10 waveguide. Oversize waveguide with proper transitions is demonstrated as an effective way to increase incident power and the return signal for broadband EPR experiments. Detailed performance characteristics, including continuous wave experiment using 1 μM 2,2,6,6-tetramethylpiperidine-1-oxyl in aqueous solution, provided here serve as a benchmark for other broadband low-loss probes in

  3. Broadband enhancement of infrared absorption in microbolometers using Ag nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Jerome K. [Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Ahn, Chi Won; Kim, Woo Choong; Kim, Tae Hyun; Hyun, Moon Seop; Kim, Hee Yeoun, E-mail: hyeounkim@nnfc.re.kr, E-mail: jhpark@nnfc.re.kr; Park, Jae Hong, E-mail: hyeounkim@nnfc.re.kr, E-mail: jhpark@nnfc.re.kr [National Nano-Fab Center, Daejeon 305-701 (Korea, Republic of); Lee, Won-Oh [S-Package Solution Co., Ltd., Daegu 702-701 (Korea, Republic of)

    2015-12-21

    High performance microbolometers are widely sought for thermal imaging applications. In order to increase the performance limits of microbolometers, the responsivity of the device to broadband infrared (IR) radiation needs to be improved. In this work, we report a simple, quick, and cost-effective approach to modestly enhance the broadband IR response of the device by evaporating Ag nanocrystals onto the light entrance surface of the device. When irradiated with IR light, strong fields are built up within the gaps between adjacent Ag nanocrystals. These fields resistively generate heat in the nanocrystals and underlying substrate, which is transduced into an electrical signal via a resistive sensing element in the device. Through this method, we are able to enhance the IR absorption over a broadband spectrum and improve the responsivity of the device by ∼11%.

  4. Light source for narrow and broadband coherent Raman scattering microspectroscopy.

    Science.gov (United States)

    Brinkmann, Maximilian; Dobner, Sven; Fallnich, Carsten

    2015-12-01

    We present a light source that is well adapted to both narrow- and broadband coherent Raman scattering (CRS) methods. Based on a single oscillator, the light source delivers synchronized broadband pulses via supercontinuum generation and narrowband, frequency-tunable pulses via four-wave mixing in a photonic crystal fiber. Seeding the four-wave mixing with a spectrally filtered part of the supercontinuum yields high-pulse energies up to 8 nJ and the possibility of scanning a bandwidth of 2000  cm(-1) in 25 ms. All pulses are emitted with a repetition frequency of 1 MHz, which ensures efficient generation of CRS signals while avoiding significant damage of the samples. Consequently, the light source combines the performance of individual narrow- and broadband CRS light sources in one setup, thus enabling hyperspectral imaging and rapid single-resonance imaging in parallel. PMID:26625022

  5. Inferring surface solar absorption from broadband satellite measurements

    Science.gov (United States)

    Cess, Robert D.; Vulis, Inna L.

    1989-01-01

    An atmospheric solar radiation model and surface albedo models that include wavelength dependence and surface anisotropy are combined to study the possibility of inferring the surface solar absorption from satellite measurements. The model includes ocean, desert, pasture land, savannah, and bog surface categories. Problems associated with converting narrowband measurements to broadband quantities are discussed, suggesting that it would be easier to infer surface solar absorption from broadband measurements directly. The practice of adopting a linear relationship between planetary and surface albedo to estimate surface albedos from satellite measurements is examined, showing that the linear conversion between broadband planetary and surface albedos is strongly dependent on vegetation type. It is suggested that there is a linear slope-offset relationship between surface and surface-atmosphere solar absorption.

  6. Swift/BAT and MAXI/GSC Broadband Transient Monitor

    CERN Document Server

    Sakamoto, Takanori; Mihara, Tatehiro; Yoshida, Atsumasa; Arimoto, Makoto; Barthelmy, Scott D; Kawai, Nobuyuki; Krimm, Hans A; Nakahira, Satoshi; Serino, Motoko

    2015-01-01

    We present the newly developed broadband transient monitor using the Swift Burst Alert Telescope (BAT) and the MAXI Gas Slit Camera (GSC) data. Our broadband transient monitor monitors high energy transient sources from 2 keV to 200 keV in seven energy bands by combining the BAT (15-200 keV) and the GSC (2-20 keV) data. Currently, the daily and the 90-minute (one orbit) averaged light curves are available for 106 high energy transient sources. Our broadband transient monitor is available to the public through our web server, http://yoshidalab.mydns.jp/bat_gsc_trans_mon/, for a wider use by the community. We discuss the daily sensitivity of our monitor and possible future improvements to our pipeline.

  7. Piezomagnetoelastic broadband energy harvester: Nonlinear modeling and characterization

    Science.gov (United States)

    Aravind Kumar, K.; Ali, S. F.; Arockiarajan, A.

    2015-11-01

    Piezomagnetoelastic energy harvesters are one among the widely explored configurations to improve the broadband characteristics of vibration energy harvesters. Such nonlinear harvesters follow a Moon beam model with two magnets at the base and one at the tip of the beam. The present article develops a geometric nonlinear mathematical model for the broadband piezomagnetoelastic energy harvester. The electromechanical coupling and the nonlinear magnetic potential equations are developed from the dimensional system parameters to describe the nonlinear dynamics exhibited by the system. The developed model is capable of characterizing the monostable, bistable and tristable operating regimes of the piezomagnetoelastic energy harvester, which are not explicit in the Duffing representation of the system. Bifurcations and attractor motions are analyzed as nonlinear functions of the distance between base magnets and the field strength of the tip magnet. The model is further used to characterize the potential wells and stable states, with due focus on the performance of the system in broadband energy harvesting.

  8. High-sensitivity broadband microwave spectroscopy with small nonresonant coils

    Science.gov (United States)

    Mahdjour, H.; Clark, W. G.; Baberschke, K.

    1986-06-01

    The use of a small, nonresonant, coil of micron dimensions as the microwave magnetic field structure of a broadband electron-spin-resonance (ESR) spectrometer is described. The coil is driven by a broadband microwave generator which operates between 0.1 and 8.5 GHz. The samples may fill the coil to approximately 100 percent. It is shown that for small size samples this system offers higher sensitivity than a conventional cavity spectrometer. Because the system is broadband, either frequency scans or the conventional magnetic field scans can be used to traverse the resonance. Examples for DPPH and for the spin glass AgMn using this method are reported. Since the sample coil is small, it has many potential applications, such as insertion into the mixing chamber of dilution refrigerator or high-pressure cell, efficient use of power in ENDOR and other double resonance experiments, and rapid recovery from transients in pulsed ESR experiments.

  9. Extracting Time-Resolved Information from Time-Integrated Laser-Induced Breakdown Spectra

    Directory of Open Access Journals (Sweden)

    Emanuela Grifoni

    2014-01-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS data are characterized by a strong dependence on the acquisition time after the onset of the laser plasma. However, time-resolved broadband spectrometers are expensive and often not suitable for being used in portable LIBS instruments. In this paper we will show how the analysis of a series of LIBS spectra, taken at different delays after the laser pulse, allows the recovery of time-resolved spectral information. The comparison of such spectra is presented for the analysis of an aluminium alloy. The plasma parameters (electron temperature and number density are evaluated, starting from the time-integrated and time-resolved spectra, respectively. The results are compared and discussed.

  10. Broadband Seismic Investigations of the Upper Mantle Beneath the Vienna and Pannonian Basins

    Science.gov (United States)

    Dando, B. D.; Stuart, G. W.; Houseman, G. A.; Team, C.

    2008-12-01

    The Carpathian Basins Project (CBP) aims to understand the origin of the Miocene-age extensional basins contained within the compressional arc of the Alpine-Carpathian system. To test competing models for the recent geological evolution of the Carpathian-Pannonian lithosphere and upper mantle, we present a new determination of P-wave velocity structure to depths of 700 km beneath this region. This model is based on inversion of seismic travel-time residuals from 97 broadband seismic stations. We include CBP data from a 15-month deployment of a high resolution network of 46 stations deployed NW-SE across the Vienna and western Pannonian basins through Austria, Hungary and Serbia, together with 10 broadband stations spread across the Pannonian basin and a further 41 permanent broadband stations. We use P-wave arrival times from approximately 341 teleseismic events. The 3-D velocity variation obtained by tomographic inversion of the P-wave travel-time residuals shows an approximately linear belt of fast material of width about 100 km, orientated WNW-ESE beneath the western Pannonian Basin at sub-lithospheric depths. This feature is apparently continuous with structure beneath the Eastern Alps, but becomes more diffuse into the transition zone. Our initial interpretation of these fast velocities is in terms of mantle downwelling related to the early collision of Adria and Europe. We use receiver functions to assess crustal structure variations. We also determine SKS anisotropy; regionally SKS varies systematically in direction, with a delay time of about 1.0s. E-W fast directions above the fast tomographic anomaly change to NW-SE across the Great Hungarian Plane and the Vienna Basin.

  11. Optimizing broadband terahertz modulation with hybrid graphene/metasurface structures.

    Science.gov (United States)

    Shi, S-F; Zeng, B; Han, H-L; Hong, X; Tsai, H-Z; Jung, H S; Zettl, A; Crommie, M F; Wang, F

    2015-01-14

    We demonstrate efficient terahertz (THz) modulation by coupling graphene strongly with a broadband THz metasurface device. This THz metasurface, made of periodic gold slit arrays, shows near unity broadband transmission, which arises from coherent radiation of the enhanced local-field in the slits. Utilizing graphene as an active load with tunable conductivity, we can significantly modify the local-field enhancement and strongly modulate the THz wave transmission. This hybrid device also provides a new platform for future nonlinear THz spectroscopy study of graphene. PMID:25483819

  12. Synchrony in broadband fluctuation and the 2008 financial crisis.

    Directory of Open Access Journals (Sweden)

    Der Chyan Lin

    Full Text Available We propose phase-like characteristics in scale-free broadband processes and consider fluctuation synchrony based on the temporal signature of significant amplitude fluctuation. Using wavelet transform, successful captures of similar fluctuation pattern between such broadband processes are demonstrated. The application to the financial data leading to the 2008 financial crisis reveals the transition towards a qualitatively different dynamical regime with many equity price in fluctuation synchrony. Further analysis suggests an underlying scale free "price fluctuation network" with large clustering coefficient.

  13. SDN-Based Broadband Network for Cloud Services

    Institute of Scientific and Technical Information of China (English)

    Xiongyan Tang; Pei Zhang; Chang Cao

    2014-01-01

    Over-the-top services and cloud services have created great challenges for telecom operators. To better meet the requirements of cloud services, we propose a decoupled network architecture. Software-defined networking/network function virtualization (SDN/NFV) will be vital in the construction of cloud-oriented broadband infrastructure, especially within data centers and for intercon-nection between data centers. We also propose introducing SDN/NFV in the broadband access network in order to realize a virtu-alized residential gateway (VRG). We discuss the deployment modes of VRG.

  14. Broadband polymer microstructured THz fiber coupler with downdoped cores

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Bang, Ole;

    2010-01-01

    We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz.......We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz....

  15. Bragg-Berry mirrors: reflective broadband q-plates.

    Science.gov (United States)

    Rafayelyan, Mushegh; Brasselet, Etienne

    2016-09-01

    We report on the experimental realization of flat mirrors enabling the broadband generation of optical vortices upon reflection. The effect is based on the geometric Berry phase associated with the circular Bragg reflection phenomenon from chiral uniaxial media. We show the reflective optical vortex generation from both diffractive and nondiffractive paraxial light beams using spatially patterned chiral liquid crystal films. The intrinsic spectrally broadband character of spin-orbit generation of optical phase singularities is demonstrated over the full visible domain. Our results do not rely on any birefringent retardation requirement and, consequently, foster the development of a novel generation of robust optical elements for spin-orbit photonic technologies. PMID:27607950

  16. Engineering the dispersion of metamaterial surface for broadband infrared absorption.

    Science.gov (United States)

    Feng, Qin; Pu, Mingbo; Hu, Chenggang; Luo, Xiangang

    2012-06-01

    We propose a broadband infrared absorber by engineering the frequency dispersion of metamaterial surface (metasurface) to mimic an ideal absorbing sheet. With a thin layer of structured nichrome, a polarization-independent absorber with absorption larger than 97% is numerically demonstrated over a larger than one octave bandwidth. It is shown that the bandwidth enhancement is related with the transformation of the Drude model of free electron gas in metal film to the Lorentz oscillator model of a bound electron in the structured metallic surface. We believe that the concept of dispersion engineering may provide helpful guidance for the design of a broadband absorber. PMID:22660145

  17. Broadband high reflectivity in subwavelength-grating slab waveguides

    CERN Document Server

    Cui, Xuan; Zhou, Zhongxiang

    2015-01-01

    We computationally study a subwavelength dielectric grating structure, show that slab waveguide modes can be used to obtain broadband high reflectivity, and analyze how slab waveguide modes influence reflection. A structure showing interference between Fabry-Perot modes, slab waveguide modes, and waveguide array modes is designed with ultra-broadband high reflectivity. Owing to the coupling of guided modes, the region with reflectivity R > 0.99 has an ultra-high bandwidth ( {\\Delta}f/f > 30%). The incident-angle region with R > 0.99 extends over a range greater than 40{\\deg}. Moreover, an asymmetric waveguide structure is studied using a semiconductor substrate.

  18. Crosstalk analysis of a broadband data communications system

    Energy Technology Data Exchange (ETDEWEB)

    Crutcher, R.I.; Ewing, P.D.; Hayes, T.W.

    1987-11-01

    A broadband cable system represents a significant resource for data transmission within a facility. Duplication of a broadband network to provide services of varying sensitivity levels within the same area is wasteful of capital resources. The sharing of a network by different data services is financially attractive providing that sensitive data are inaccessible from nonsensitive ports. The use of equipment from two manufacturers introduces a deliberate incompatibility for the purpose of data isolation. This report presents test results obtained by this technique. 4 refs., 26 figs.

  19. The Quest for Ultimate Broadband High Power Microwaves

    CERN Document Server

    Podgorski, Andrew S

    2014-01-01

    Paper describes High Power Microwave research of combining GW peak power to achieve MV/m and GV/m radiated fields in 1 to 500 GHz band. To achieve such fields multiple independently triggered broadband GW sources, supplying power to multiple spatially distributed broadband radiators/antennas are used. Single TW array is used as an ultimate microwave weapon in 1 to 5 GHz range while multiple TW arrays provide GV/m radiating field at plasma frequencies in 300 GHz range leading to fusion power.

  20. Experimental Demonstration of Quantum Teleportation of Broadband Squeezing

    Science.gov (United States)

    Yonezawa, Hidehiro; Braunstein, Samuel L.; Furusawa, Akira

    2007-09-01

    We demonstrate an unconditional high-fidelity teleporter capable of preserving the broadband entanglement in an optical squeezed state. In particular, we teleport a squeezed state of light and observe -0.8±0.2dB of squeezing in the teleported (output) state. We show that the squeezing criterion translates directly into a sufficient criterion for entanglement of the upper and lower sidebands of the optical field. Thus, this result demonstrates the first unconditional teleportation of broadband entanglement. Our teleporter achieves sufficiently high fidelity to allow the teleportation to be cascaded, enabling, in principle, the construction of deterministic non-Gaussian operations.

  1. Symmetry-Breaking Plasmonic Metasurfaces for Broadband Light Bending

    DEFF Research Database (Denmark)

    Ni, Xingjie; Emani, Naresh K.; Kildishev, Alexander V.;

    2012-01-01

    We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface.......We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface....

  2. A novel structure for a broadband left-handed metamaterial

    Institute of Scientific and Technical Information of China (English)

    Xiong Han; Hong Jing-Song; Jin Da-Lin; Zhang Zhi-Min

    2012-01-01

    A low absorptivity broadband negative refractive index metamaterial with a multi-gap split-ring and metallic cross (MSMC) structure is proposed and investigated numerically and experimentally in the microwave frequency range.The effective media parameters were retrieved from the numerical and experimental results,which clearly show that there exists a very wide frequency band where the permittivity and permeability are negative.The influence of the structure parameters on the magnetic response and the cut-off frequency of the negative permittivity are studied in detail.This metamaterial would have potential application in designing broadband microwave devices.

  3. Analysis of broadband aerodynamic noise from VS45

    Energy Technology Data Exchange (ETDEWEB)

    Dundabin, P. [Renewable Energy Systems Ltd., Glasgow, Scotland (United Kingdom)

    1997-12-31

    This paper describes the analysis of acoustic data taken from the VS45 at Kaiser-Wilhelm-Koog. The aim was to investigate the dependence of aerodynamic noise on tip speed and angle of attack. In particular, the dependence of noise in individual third octave bands on these variable is examined. The analysis is divided into 3 sections: data selection, data checks and analysis of broadband nacelle noise; analysis of broadband aerodynamic noise and its sensitivity to tip speed and angle of attack. (LN)

  4. Implementation of Scientific Computing Applications on the Cell Broadband Engine

    Directory of Open Access Journals (Sweden)

    Guochun Shi

    2009-01-01

    Full Text Available The Cell Broadband Engine architecture is a revolutionary processor architecture well suited for many scientific codes. This paper reports on an effort to implement several traditional high-performance scientific computing applications on the Cell Broadband Engine processor, including molecular dynamics, quantum chromodynamics and quantum chemistry codes. The paper discusses data and code restructuring strategies necessary to adapt the applications to the intrinsic properties of the Cell processor and demonstrates performance improvements achieved on the Cell architecture. It concludes with the lessons learned and provides practical recommendations on optimization techniques that are believed to be most appropriate.

  5. Bragg-Berry mirrors: reflective broadband q-plates

    CERN Document Server

    Rafayelyan, Mushegh

    2016-01-01

    We report on the experimental realization of flat mirrors enabling the broadband generation of optical vortices upon reflection. The effect is based on the geometric Berry phase associated with the circular Bragg reflection phenomenon from chiral uniaxial media. We show the reflective optical vortex generation from both diffractive and nondiffractive paraxial light beams using spatially patterned chiral liquid crystal films. The intrinsic spectrally broadband character of spin-orbit generation of optical phase singularities is demonstrated over the full visible domain. Our results do not rely on any birefringent retardation requirement and consequently foster the development of a novel generation of robust optical elements for spin-orbit photonic technologies.

  6. The Swift BAT-detected Seyfert 1 Galaxies: X-ray Broadband Properties and Warm Absorbers

    CERN Document Server

    Winter, Lisa M; McKernan, Barry; Kallman, Tim

    2011-01-01

    We present results from an analysis of the broad-band, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased towards both obscuration and host galaxy properties. Our detailed and uniform model fits to Suzaku/BAT and XMM-Newton/BAT spectra include the neutral absorption, direct power-law, reflected emission, soft excess, warm absorption, and narrow Fe K-alpha emission properties for the entire sample. We significantly detect O VII and O VIII edges in 52% of our sample. The strength of these detections are strongly correlated with the neutral column density measured in the spectrum. Among the strongest detections, X-ray grating and UV observations, where available, indicate outflowing material. The ionized column densities of sources with O VII and O VIII detections are clustered in a narrow range with N$_{\\rm war...

  7. The σ-hole interaction between sulfur hexafluoride and ammonia characterised by broadband rotational spectroscopy.

    Science.gov (United States)

    Bittner, Dror M; Zaleski, Daniel P; Stephens, Susanna L; Walker, Nicholas R; Legon, Anthony C

    2015-08-24

    A weakly-bound complex of SF6 and NH3 is generated within an expanding gas jet and characterised by broadband rotational spectroscopy. The spectra of isotopologues (32) SF6 ⋅⋅⋅(14) NH3 , (32) SF6 ⋅⋅⋅(14) ND3 , (32) SF6 ⋅⋅⋅(15) NH3 and (34) SF6 ⋅⋅⋅(15) NH3 are observed and assigned to determine the spectroscopic parameters. These parameters are consistent with the complex having a C3v symmetric rotor geometry, in which the nitrogen atom of NH3 coordinates to SF6 such that the C3v axis of the NH3 sub-unit is aligned with a local C3 axis on the SF6 sub-unit. The geometry of the complex is rationalized in terms of a σ-hole interaction. The observed spectra and ab initio calculations also reveal evidence of internal dynamics involving internal rotation of one monomer sub-unit with respect to the other about the symmetry axis of the complex. PMID:26175274

  8. Mechanism for Broadband White-Light Emission from Two-Dimensional (110) Hybrid Perovskites.

    Science.gov (United States)

    Hu, Te; Smith, Matthew D; Dohner, Emma R; Sher, Meng-Ju; Wu, Xiaoxi; Trinh, M Tuan; Fisher, Alan; Corbett, Jeff; Zhu, X-Y; Karunadasa, Hemamala I; Lindenberg, Aaron M

    2016-06-16

    The recently discovered phenomenon of broadband white-light emission at room temperature in the (110) two-dimensional organic-inorganic perovskite (N-MEDA)[PbBr4] (N-MEDA = N(1)-methylethane-1,2-diammonium) is promising for applications in solid-state lighting. However, the spectral broadening mechanism and, in particular, the processes and dynamics associated with the emissive species are still unclear. Herein, we apply a suite of ultrafast spectroscopic probes to measure the primary events directly following photoexcitation, which allows us to resolve the evolution of light-induced emissive states associated with white-light emission at femtosecond resolution. Terahertz spectra show fast free carrier trapping and transient absorption spectra show the formation of self-trapped excitons on femtosecond time-scales. Emission-wavelength-dependent dynamics of the self-trapped exciton luminescence are observed, indicative of an energy distribution of photogenerated emissive states in the perovskite. Our results are consistent with photogenerated carriers self-trapped in a deformable lattice due to strong electron-phonon coupling, where permanent lattice defects and correlated self-trapped states lend further inhomogeneity to the excited-state potential energy surface. PMID:27246299

  9. An ATCA Survey of Sagittarius~B2 at 7~mm: Chemical Complexity Meets Broadband Interferometry

    CERN Document Server

    Corby, Joanna F; Cunningham, Maria R; Menten, Karl M; Belloche, Arnaud; Schwab, Frederic R; Walsh, Andrew J; Balnozan, Egon; Bronfman, Leonardo; Lo, Nadia; Remijan, Anthony J

    2015-01-01

    We present a 30 - 50 GHz survey of Sagittarius B2(N) conducted with the Australia Telescope Compact Array (ATCA) with 5 - 10 arcsec resolution. This work releases the survey data and demonstrates the utility of scripts that perform automated spectral line fitting on broadband line data. We describe the line-fitting procedure, evaluate the performance of the method, and provide access to all data and scripts. The scripts are used to characterize the spectra at the positions of three HII regions, each with recombination line emission and molecular line absorption. Towards the most line-dense of the three regions characterised in this work, we detect ~500 spectral line components of which ~90 per cent are confidently assigned to H and He recombination lines and to 53 molecular species and their isotopologues. The data reveal extremely subthermally excited molecular gas absorbing against the continuum background at two primary velocity components. Based on the line radiation over the full spectra, the molecular a...

  10. Broadband Wireline Provider Service: Optical Carrier - Fiber to the End User; BBRI_fiber12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Optical Carrier - Fiber to the End User" technology. Broadband...

  11. Broadband Wireline Provider Service: Cable Modem - DOCSIS 3.0; BBRI_cableDOCSIS12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - DOCSIS 3.0" technology. Broadband availability is...

  12. Broadband Wireline Provider Service: Cable Modem - Other; BBRI_cableOther12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - Other" technology. Broadband availability is...

  13. Broadband Wireline Provider Service: Symmetric xDSL; BBRI_DSLsym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Symmetric xDSL technology. Broadband availability is summarized...

  14. Broadband Wireline Provider Service: Asymmetric xDSL; BBRI_DSLasym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Asymmetric xDSL technology. Broadband availability is summarized...

  15. 77 FR 12951 - Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

    Science.gov (United States)

    2012-03-02

    ..., radiolocation, and digital audio broadcasting satellite uses. The Commission defined... and Modernization, Advancing Broadband Availability Through Digital Literacy Training; Final Rule #0...] Lifeline and Link Up Reform and Modernization, Advancing Broadband Availability Through Digital...

  16. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  17. Broadband, High-Temperature Ultrasonic Transducer

    Science.gov (United States)

    Parker, F. Raymond; Winfree, William P.; Barrows, Danny A.

    1995-01-01

    Materials chosen for endurance at high temperatures and acoustic coupling and damping. Acoustic transducer designed to exhibit broad frequency response and to survive temperatures close to melting points of brazing alloys. Attached directly and continuously to hot object monitored ultrasonically: for example, it can be attached to relatively cool spot on workpiece during brazing for taking ultrasonic quality-control measurements.

  18. Blazar jets the spectra

    CERN Document Server

    Ghisellini, G

    2000-01-01

    The radiation observed by blazars is believed to originate from the transformation of bulk kinetic energy of relativistic jets into random energy. A simple way to achieve this is to have an intermittent central power source, producing shells of plasma with different bulk Lorentz factors. These shells will collide at some distance from the center, producing shocks and then radiation. This scenario, called internal shock model, is thought to be at the origin of the gamma-rays observed in gamma-ray bursts and can work even better in blazars. It accounts for the observed key characteristics of these objects, including the fact that radiation must be preferentially produced at a few hundreds of Schwarzschild radii from the center, but continues to be produced all along the jet. At the kpc scale and beyond, the slowly moving parts of a (straight) jet can be illuminated by the beamed radiation of the core, while the fast parts of the jet will see enhanced cosmic microwave radiation. In both cases the Inverse Compton...

  19. A Design of 45-Degree Dual-Polarization Broadband Plane Station Antenna

    OpenAIRE

    Jianming Zhou

    2015-01-01

    A new broadband planar dual-polarization base station antenna is proposed, the antenna consists of two broadband plane coplanar base station antenna units, and so it has features of plane antenna. Two broadband plane station antenna units can, respectively, form double polarization in the direction. We analyzed the relative positions between the two antenna units and their effects on the performances of the antenna, especially for the influence of isolation. Broadband antenna has the characte...

  20. The Impact of Broadband on U.S. Agriculture: An Evaluation of the USDA Broadband Loan Program

    OpenAIRE

    Kandilov, Amy M.G.; Kandilov, Ivan T.; Liu, Xiangping; Renkow, Mitch

    2011-01-01

    We evaluate the impact of USDA’s low-cost broadband loan programs on the U.S. agricultural sector. The broadband loan programs increase access to high-speed internet in recipient communities, which can raise farm sales by increasing both farm output and prices received by producers. Further, high-speed internet may drive down costs by providing information on cheaper inputs and better management practices, leading to an overall improvement in farm profits. Using data from the 1997, 2002, and ...

  1. The Evolution of South Korea's Broadband Convergence Network, 2004-2007

    Science.gov (United States)

    Menon, Siddhartha Shankar

    2010-01-01

    Broadband holds a critical position in the progress of economic and social indicators by connecting consumers, businesses and governments. South Korea has consistently been the global leader in broadband deployment since 1999. In the last ten years the Korean government has pursued several strategies for its broadband policy. The purpose of this…

  2. Libraries Use Broadband Internet Service to Serve High Need Communities. Data Note. Number 1

    Science.gov (United States)

    Pastore, Erica; Henderson, Everett

    2009-01-01

    America needs greater access to broadband Internet to spur economic growth, innovation, and job creation. To date, gains in household broadband take-up are not evenly distributed across all demographic groups or geographic areas. While from 2001 to 2007, the percentage of households in the United States with access to broadband Internet services…

  3. Community Broadband Networks and the Opportunity for E-Government Services

    DEFF Research Database (Denmark)

    Williams, Idongesit

    2016-01-01

    Community Broadband Networks (CBN) facilitate Broadband connectivity in underserved areas in many countries. The lack of Broadband connectivity is one of the reasons for the slow diffusion of e-government services in many countries.This article explains how CBNs can be enabled by governments to f...

  4. Realization of modulating broadband emission from Er–Tm codoped calcium boroaluminate glasses by dual-wavelength pumping

    International Nuclear Information System (INIS)

    Near-infrared photoluminescence (PL) of calcium boroaluminate (CABAL) glasses codoped with Er2O3 and Tm2O3 has been investigated by dual-wavelength pumping at 795 and 476 nm. Spectrum shape of broadband emission could be modulated by controlling the power ratio of two pumping lines (P476/P795). The result shows that the full width at half maximum can reach ∼500 nm in the wavelength range from 1.3 to 2.0 μm by controlling P476/P795 = 12. The PL spectra show four characteristic peaks located at 1.46, 1.53, 1.58 and 1.80 μm, corresponding to Tm3+: 3H4 → 3F4, Er3+: 4I13/2 → 4I15/2, Tm3+: 1G4 → 3F2 and Tm3+: 3F4 → 3H6 emissions, respectively. The energy transfer (ET) (ET1: Er3+: 4I13/2, Tm3+: 3F4 → Er3+: 4I15/2, Tm3+: 3H4 and ET2: Er3+: 4I13/2, Tm3+: 3H6 → Er3+: 4I15/2, Tm3+: 3F4) between Er3+ and Tm3+ ions play important roles in the luminescence mechanisms. In addition, a new ET process (ET: Tm3+: 1G4, Er3+: 4F9/2 → Tm3+: 3F2, Er3+: 4F7/2) was identified. The flat broadband emission with the bandwidth of ∼500 nm could be realized by changing P476/P795 as a result of the radiative transitions, Tm–Tm cross-relaxation (Tm3+: 3H4, 3H6 → Tm3+: 3F4, 3F4) and Er–Tm ET processes. -- Highlights: ► Dual-wavelength pumping has been applied to modulate broadband emission in rare-earth-doped materials. ► It is easier to control the pumping source than the concentration of sample for modulating broadband emission. ► The broadband and flat emission with the bandwidth of ∼500 nm has been realized through dual-wavelength. ► This would be caused by the radiative transitions, Tm–Tm cross-relaxation and Er–Tm energy transfer processes.

  5. Inverse design of an ultra-compact broadband optical diode based on asymmetric spatial mode conversion.

    Science.gov (United States)

    Callewaert, Francois; Butun, Serkan; Li, Zhongyang; Aydin, Koray

    2016-01-01

    The objective-first inverse-design algorithm is used to design an ultra-compact optical diode. Based on silicon and air only, this optical diode relies on asymmetric spatial mode conversion between the left and right ports. The first even mode incident from the left port is transmitted to the right port after being converted into an odd mode. On the other hand, same mode incident from the right port is reflected back by the optical diode dielectric structure. The convergence and performance of the algorithm are studied, along with a transform method that converts continuous permittivity medium into a binary material design. The optimal device is studied with full-wave electromagnetic simulations to compare its behavior under right and left incidences, in 2D and 3D settings as well. A parametric study is designed to understand the impact of the design space size and initial conditions on the optimized devices performance. A broadband optical diode behavior is observed after optimization, with a large rejection ratio between the two transmission directions. This illustrates the potential of the objective-first inverse-design method to design ultra-compact broadband photonic devices. PMID:27586852

  6. A novel high-brightness broadband light-source technology from the VUV to the IR

    Science.gov (United States)

    Horne, Stephen; Smith, Don; Besen, Matthew; Partlow, Matthew; Stolyarov, Daniil; Zhu, Huiling; Holber, William

    2010-04-01

    A novel technology has been developed which enables high-brightness, broadband light output from the VUV to the IR spectral regions. A focused laser is used to sustain a high-pressure xenon discharge inside a bulb, creating a smaller, hotter discharge than can be obtained by using an electrically-driven discharge. This allows for continuous output down to 120 nm wavelength and into the infrared. Application areas include hyperspectral imaging, standoff detection, surveillance, bioanalytical instrumentation, microscopy, and materials studies. Laser-driven optical discharges were first investigated over 30 years ago, providing the initial technical understanding of such discharges. However it took the convergence of two separate elements - the availability of low-cost, high-efficiency CW diode lasers; and a market need for high-brightness, broadband light source - to provide the impetus for further development in this area. Using near-IR CW diode lasers at power levels from 15 W to over 2000 W, we have generated high-pressure xenon discharges having temperatures as high as 10,000 C. The optical brightness of these discharges can be over an order of magnitude higher than those obtainable from the brightest xenon arc lamps, and can be several orders of magnitude brighter than deuterium lamps. Results from modeling of these discharges as well as experimental measurements will be presented.

  7. Novel broadband glass phosphors for high CRI WLEDs.

    Science.gov (United States)

    Chen, Li-Yin; Cheng, Wei-Chih; Tsai, Chun-Chin; Chang, Jin-Kai; Huang, Yi-Chung; Huang, Jhih-Ci; Cheng, Wood-Hi

    2014-05-01

    New broadband glass phosphors with excellent thermal stability were proposed and experimentally demonstrated for white light-emitting-diodes (WLEDs). The novel glass phosphors were realized through dispersing multiple phosphors into SiO₂ based glass (SiO₂-Na₂O-Al₂O₃-CaO) at 680°C. Y₃Al₅O₁₂:Ce³⁺ (YAG), Lu₃Al₅O₁₂:Ce³⁺ (LuAG), and CaAlSiN₃: Eu²⁺ (nitride) phosphor crystals were chosen respectively as the yellow, green, and red emitters of the glass phosphors. The effect of sintering temperature on inter-diffusion reduction between phosphor crystals and amorphous SiO₂ in nitride-doped glass phosphors was studied and evidenced by the aid of high-resolution transmission electron microscopy (HRTEM). Broadband glass phosphors with high quantum-yield of 55.6% were thus successfully realized through the implementation of low sintering temperature. Proof-of-concept devices utilizing the novel broadband phosphors were developed to generate high-quality cool-white light with trisstimulus coordinates (x, y) = (0.358, 0.288), color-rending index (CRI) = 85, and correlated color temperature (CCT) = 3923K. The novel broadband glass phosphors with excellent thermal stability are essentially beneficial to the applications for next-generation solid-state indoor lighting, especially in the area where high power and absolute reliability are required. PMID:24922375

  8. Architectures for ku-band broadband airborne satellite communication antennas

    NARCIS (Netherlands)

    Verpoorte, Jaco; Schippers, Harmen; Jorna, Pieter; Roeloffzen, Chris G.H.; Marpaung, David A.I.; Baggen, Rens; Sanadgol, Bahram

    2010-01-01

    This paper describes different architectures for a broadband antenna for satellite communication on aircraft. The antenna is a steerable (conformal) phased array antenna in Ku-band (receive-only). First the requirements for such a system are addressed. Subsequently a number of potential architecture

  9. Nonlinear piezomagnetoelastic harvester array for broadband energy harvesting

    Science.gov (United States)

    Upadrashta, Deepesh; Yang, Yaowen

    2016-08-01

    This article proposes an array of nonlinear piezomagnetoelastic energy harvesters (NPEHs) for scavenging electrical energy from broadband vibrations with low amplitudes (parallel connections between the individual harvesters using standard AC/DC interface circuits is also investigated and compared with its linear counterpart.

  10. Global Interoperability of Broadband Networks (GIBN): Project Overview

    Science.gov (United States)

    DePaula, Ramon P.

    1998-01-01

    Various issues associated with the Global Interoperability of Broadband Networks (GIBN) are presented in viewgraph form. Specific topics include GIBN principles, objectives and goals, and background. GIBN/NASA status, the Transpacific High Definition Video experiment, GIBN experiment selection criteria, satellite industry involvement, and current experiments associated with GIBN are also discussed.

  11. China Netcom: Stressing on Broadband and Building an Innovative Enterprise

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    China Network Communications Group Corporation (CNC) proposed and reaffirmed for many times the strategic objective of transferring to a broadband communication and multimedia service provider since the beginning of this year. CNC, insisting on self-innovation, is going to forge itself into a domestically high-class and internationally influential innovative company within five years.

  12. 78 FR 25787 - Community Connect Broadband Grant Program

    Science.gov (United States)

    2013-05-03

    ... its Proposed Rule, published in the Federal Register on November 16, 2012, ] (77 FR 68705), the agency... their own may not provide ubiquitous coverage in an area, if broadband service is available in an area..., education, health, and safety of rural Americans. The purpose of the Community Connect Grant Program is...

  13. Coherent broadband light source for parallel optical coherence tomography

    NARCIS (Netherlands)

    Rivier, S.; Laversenne, L.; Bourquin, S.; Salathé, R.P.; Pollnau, M.; Grivas, C.; Shepherd, D.P.; Eason, R.W.; Flury, M.; Philipoussis, I.; Herzig, H.P.

    2004-01-01

    A Ti:sapphire planar waveguide is rib structured by Ar ion milling to provide parallel channel waveguides. By coupling high-power pump light through a microlens array into the waveguides, a novel broadband luminescent parallel emitter is demonstrated as a light source for parallel optical coherence

  14. Rapidly converging multichannel controllers for broadband noise and vibrations

    NARCIS (Netherlands)

    Berkhoff, A.P.

    2010-01-01

    Applications are given of a preconditioned adaptive algorithm for broadband multichannel active noise control. Based on state-space descriptions of the relevant transfer functions, the algorithm uses the inverse of the minimum-phase part of the secondary path in order to improve the speed of converg

  15. A stochastic approach to robust broadband structural control

    Science.gov (United States)

    Macmartin, Douglas G.; Hall, Steven R.

    1992-01-01

    Viewgraphs on a stochastic approach to robust broadband structural control are presented. Topics covered include: travelling wave model; dereverberated mobility model; computation of dereverberated mobility; power flow; impedance matching; stochastic systems; control problem; control of stochastic systems; using cost functional; Bernoulli-Euler beam example; compensator design; 'power' dual variables; dereverberation of complex structure; and dereverberated transfer function.

  16. Nonlinear Analysis of Renal Autoregulation Under Broadband Forcing Conditions

    DEFF Research Database (Denmark)

    Marmarelis, V Z; Chon, K H; Chen, Y M;

    1994-01-01

    Linear analysis of renal blood flow fluctuations, induced experimentally in rats by broad-band (pseudorandom) arterial blood pressure forcing at various power levels, has been unable to explain fully the dynamics of renal autoregulation at low frequencies. This observation has suggested the possi...

  17. A Broadband Metasurface-Based Terahertz Flat-Lens Array

    KAUST Repository

    Wang, Qiu

    2015-02-12

    A metasurface-based terahertz flat-lens array is proposed, comprising C-shaped split-ring resonators exhibiting locally engineerable phase discontinuities. Possessing a high numerical aperture, the planar lens array is flexible, robust, and shows excellent focusing characteristics in a broadband terahertz frequency. It could be an important step towards the development of planar terahertz focusing devices for practical applications.

  18. Drivers and barriers for development of alternative broadband

    DEFF Research Database (Denmark)

    Tadayoni, Reza; Sigurdsson, Halldór Matthias

    2005-01-01

    Alternative broadband infrastructures are emerging and developing very fast. Different technologies and organization/business models have been used to establish these networks. The aim of the paper is to understand and identify the technological, economic and political/regulatory drivers and barr...

  19. Broadband microwave photonic phase shifter based on polarisation rotation

    DEFF Research Database (Denmark)

    Xue, Weiqi; Öhman, Filip; Blaaberg, Søren;

    2008-01-01

    A broadband microwave photonic phase shifter is presented based on the polarisation properties of a Mach-Zehnder intensity modulator and nonlinear polarisation rotation in a semiconductor optical amplifier. The system can realise about 150deg phase shift in the frequency range from 50 MHz to 19 GHz....

  20. 78 FR 8353 - Rural Broadband Access Loans and Loan Guarantees

    Science.gov (United States)

    2013-02-06

    ... vital to health care provision in rural communities, whether simply improving the perception of locally... referred to as the Agency, is adopting as final, with change, an interim rule (published at 76 FR 13770 on..., economic, and social factors can overcome common barriers to broadband expansion. In general, rural...

  1. Linearization Technologies for Broadband Radio-Over-Fiber Transmission Systems

    Directory of Open Access Journals (Sweden)

    Xiupu Zhang

    2014-11-01

    Full Text Available Linearization technologies that can be used for linearizing RoF transmission are reviewed. Three main linearization methods, i.e. electrical analog linearization, optical linearization, and electrical digital linearization are presented and compared. Analog linearization can be achieved using analog predistortion circuits, and can be used for suppression of odd order nonlinear distortion components, such as third and fifth order. Optical linearization includes mixed-polarization, dual-wavelength, optical channelization and the others, implemented in optical domain, to suppress both even and odd order nonlinear distortion components, such as second and third order. Digital predistortion has been a widely used linearization method for RF power amplifiers. However, digital linearization that requires analog to digital converter is severely limited to hundreds of MHz bandwidth. Instead, analog and optical linearization provide broadband linearization with up to tens of GHz. Therefore, for broadband radio over fiber transmission that can be used for future broadband cloud radio access networks, analog and optical linearization are more appropriate than digital linearization. Generally speaking, both analog and optical linearization are able to improve spur-free dynamic range greater than 10 dB over tens of GHz. In order for current digital linearization to be used for broadband radio over fiber transmission, the reduced linearization complexity and increased linearization bandwidth are required. Moreover, some digital linearization methods in which the complexity can be reduced, such as Hammerstein type, may be more promising and require further investigation.

  2. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    Science.gov (United States)

    Qi, Dong-Xiang; Fan, Ren-Hao; Deng, Yu-Qiang; Peng, Ru-Wen; Wang, Mu; Jiangnan University Collaboration

    In this talk, we present our studies on broadband properties of acoustic waves through metal gratings. We have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing and new acoustic devices. References: [1] Dong-Xiang Qi, Yu-Qiang Deng, Di-Hu Xu, Ren-Hao Fan, Ru-Wen Peng, Ze-Guo Chen, Ming-Hui Lu, X. R. Huang and Mu Wang, Appl. Phys. Lett. 106, 011906 (2015); [2] Dong-Xiang Qi, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Ming-Hui Lu, Xu Ni, Qing Hu, and Mu Wang, Applied Physics Letters 101, 061912 (2012).

  3. Broad-band hard X-ray reflectors

    DEFF Research Database (Denmark)

    Joensen, K.D.; Gorenstein, P.; Hoghoj, P.;

    1997-01-01

    Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity of ...

  4. 77 FR 68705 - Community Connect Broadband Grant Program

    Science.gov (United States)

    2012-11-16

    ..., Program Development and Regulatory Analysis, USDA Rural Development, 1400 Independence Avenue, STOP 1522..., broadband, electric, water and environmental infrastructure. Financial assistance is provided to rural... analysis of the challenges of the following criteria, laid out on a community-wide basis, and how...

  5. K/Ka-band Antenna for Broadband Aeronautical Mobile Application

    Science.gov (United States)

    Densmore, A.

    1994-01-01

    The Jet Propulsion Laboratory (JPL) has recently begun the development of a Broadband Aeronauical Terminal (BAT) for duplex video satellite communications on commercial or business class aircraft. The BAT is designed for use with NASA's K/Ka-band Advanced Communications Technology Satellite (ACTS).

  6. Distributed Shared Memory for the Cell Broadband Engine (DSMCBE)

    DEFF Research Database (Denmark)

    Larsen, Morten Nørgaard; Skovhede, Kenneth; Vinter, Brian

    2009-01-01

    in and out of non-coherent local storage blocks for each special processor element. In this paper we present a software library, namely the Distributed Shared Memory for the Cell Broadband Engine (DSMCBE). By using techniques known from distributed shared memory DSMCBE allows programmers to program the CELL...

  7. Vectorized Data Processing on the Cell Broadband Engine

    NARCIS (Netherlands)

    Héman, S.; Nes, N.J.; Zukowski, M.; Boncz, P.A.

    2007-01-01

    In this work, we research the suitability of the Cell Broadband Engine for database processing. We start by outlining the main architectural features of Cell and use microbenchmarks to characterize the latency and throughput of its memory infrastructure. Then, we discuss the challenges of porting RD

  8. Bottle microresonator broadband and low repetition rate frequency comb generator

    CERN Document Server

    Dvoyrin, V

    2016-01-01

    We propose a new type of broadband and low repetition rate frequency comb generator which has the shape of an elongated and nanoscale-shallow optical bottle microresonator created at the surface of an optical fiber. The free spectral range (FSR) of the broadband azimuthal eigenfrequency series of this resonator is the exact multiple of the FSR of the dense and narrowband axial series. The effective radius variation of the microresonator is close to a parabola with a nanoscale height which is greater or equal to lambda/2pi*n0 (here lambda is the characteristic radiation wavelength and n0 is the refractive index of the microresonator material). Overall, the microresonator possesses a broadband, small FSR, and accurately equidistant spectrum convenient for the generation of a broadband and low repetition rate optical frequency comb. It is shown that this comb can be generated by pumping with a cw laser, which radiation frequency matches a single axial eigenfrequency of the microresonator, or, alternatively, by p...

  9. Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

    DEFF Research Database (Denmark)

    Gritti, Claudia; Raza, Søren; Kadkhodazadeh, Shima;

    2016-01-01

    . Optical characterization confirms that the random array of electroless-deposited NPs improves absorption by up to 20% in a broadband of nearinfrared frequencies from the bandgap edge to 2000 nm. Due to the small filling fraction of particles, the reflection in the visible range is practically unchanged...

  10. PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer

    DEFF Research Database (Denmark)

    Narendra, K.; Limiti, E.; Paoloni, C.;

    2013-01-01

    A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω...

  11. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  12. Pileup correction of microdosimetric spectra

    CERN Document Server

    Langen, K M; Lennox, A J; Kroc, T K; De Luca, P M

    2002-01-01

    Microdosimetric spectra were measured at the Fermilab neutron therapy facility using low pressure proportional counters operated in pulse mode. The neutron beam has a very low duty cycle (<0.1%) and consequently a high instantaneous dose rate which causes distortions of the microdosimetric spectra due to pulse pileup. The determination of undistorted spectra at this facility necessitated (i) the modified operation of the proton accelerator to reduce the instantaneous dose rate and (ii) the establishment of a computational procedure to correct the measured spectra for remaining pileup distortions. In support of the latter effort, two different pileup simulation algorithms using analytical and Monte-Carlo-based approaches were developed. While the analytical algorithm allows a detailed analysis of pileup processes it only treats two-pulse and three-pulse pileup and its validity is hence restricted. A Monte-Carlo-based pileup algorithm was developed that inherently treats all degrees of pileup. This algorithm...

  13. Broadband assessment of degree-2 gravitational changes from GRACE and other estimates, 2002-2015

    Science.gov (United States)

    Chen, J. L.; Wilson, C. R.; Ries, J. C.

    2016-03-01

    Space geodetic measurements, including the Gravity Recovery and Climate Experiment (GRACE), satellite laser ranging (SLR), and Earth rotation provide independent and increasingly accurate estimates of variations in Earth's gravity field Stokes coefficients ΔC21, ΔS21, and ΔC20. Mass redistribution predicted by climate models provides another independent estimate of air and water contributions to these degree-2 changes. SLR has been a successful technique in measuring these low-degree gravitational changes. Broadband comparisons of independent estimates of ΔC21, ΔS21, and ΔC20 from GRACE, SLR, Earth rotation, and climate models during the GRACE era from April 2002 to April 2015 show that the current GRACE release 5 solutions of ΔC21 and ΔS21 provided by the Center for Space Research (CSR) are greatly improved over earlier solutions and agree remarkably well with other estimates, especially on ΔS21 estimates. GRACE and Earth rotation ΔS21 agreement is exceptionally good across a very broad frequency band from intraseasonal, seasonal, to interannual and decadal periods. SLR ΔC20 estimates remain superior to GRACE and Earth rotation estimates, due to the large uncertainty in GRACE ΔC20 solutions and particularly high sensitivity of Earth rotation ΔC20 estimates to errors in the wind fields. With several estimates of ΔC21, ΔS21, and ΔC20 variations, it is possible to estimate broadband noise variance and noise power spectra in each, given reasonable assumptions about noise independence. The GRACE CSR release 5 solutions clearly outperform other estimates of ΔC21 and ΔS21 variations with the lowest noise levels over a broad band of frequencies.

  14. Infrared spectra of some fructans

    OpenAIRE

    Grube, M.; Bekers, M.; Upite, D.; Kaminska, E.

    2002-01-01

    The FT–IR spectra of fructan – inulin (RAFTILINE), widely applied in the food industry and crystalline fructose as the main component of fructans, were studied. Special interest was to study the spectra of the levan precipitate and fructan syrup – produced by Zymomonas mobilis during the fermentation on sucrose–based medium.It was shown that levan precipitate and fructose syrup does not contain lipids and nucleic acids. Levan precipitate consists of ∼93% of fructose and admixture of glucose, ...

  15. Response spectra in alluvial soils

    International Nuclear Information System (INIS)

    For aseismic design of structures, the ground motion data is assumed either in the form of ground acceleration as a function of time or indirectly in the form of response spectra. Though the response spectra approach has limitations like not being applicable for nonlinear problems, it is usually used for structures like nuclear power plants. Fifty accelerograms recorded at alluvial sites have been processed. Since different empirical formulas relating acceleration with magnitude and distance give a wide scatter of values, peak ground acceleration alone cannot be the parameter as is assumed by a number of authors. The spectra corresponding to 5% damping have been normalised with respect to three parameters, namely, peak ground acceleration, peak ground velocity and a nondimensional quantity ad/v2. Envelopee of maxima and minima as well as average response spectra has been obtained. A comparison with the USAEC spectra has been made. A relation between ground acceleration, ground velocity and ad/v2 has been obtained which would nearly give the same magnification of the response. A design response spectra for alluvial soils has been recommended. (author)

  16. Measuring Broadband IR Irradiance in the Direct Solar Beam (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 um and 50 um, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 um to 3 um, while the present photovoltaic cells are limited to approximately 0.3 um to 1 um. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and are calibrated with traceability to consensus reference, yet are calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 um to 50 um, as a first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degrees to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  17. Measuring Broadband IR Irradiance in the Direct Solar Beam (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Reda, I.; Konings, J.; Xie, Y.; Dooraghi, M.; Sengupta, M.

    2015-03-01

    Solar and atmospheric science radiometers, e.g. pyranometers, pyrheliometers, and photovoltaic cells are calibrated with traceability to a consensus reference, which is maintained by Absolute Cavity Radiometers (ACRs). The ACR is an open cavity with no window, developed to measure extended broadband direct solar irradiance beyond the ultraviolet and infrared bands below and above 0.2 micrometers and 50 micrometers, respectively. On the other hand, pyranometers and pyrheliometers are developed to measure broadband shortwave irradiance from approximately 0.3 micrometers to 3 micrcometers, while the present photovoltaic cells are limited to approximately 0.3 micrometers to 1 micrometers. The broadband mismatch of ACR versus such radiometers causes discrepancy in radiometers' calibration methods that has not been discussed or addressed in the solar and atmospheric science literature. Pyrgeometers are also used for solar and atmospheric science applications and calibrated with traceability to consensus reference, yet calibrated during nighttime only, because no consensus reference has yet been established for the daytime longwave irradiance. This poster shows a method to measure the broadband IR irradiance in the direct solar beam from 3 micrometers to 50 micrometers, as first step that might be used to help develop calibration methods to address the mismatch between broadband ACR and shortwave radiometers, and the lack of a daytime reference for pyrgeometers. The irradiance was measured from sunrise to sunset for 5 days when the sun disk was cloudless; the irradiance varied from approximately 1 Wm-2 to 16 Wm-2 for solar zenith angle from 80 degres to 16 degrees respectively; estimated uncertainty is 1.5 Wm-2.

  18. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  19. Fiber-Wireless (FiWi Broadband Access Networks in an Age of Convergence: Past, Present, and Future

    Directory of Open Access Journals (Sweden)

    Martin Maier

    2014-01-01

    Full Text Available After describing the beginnings and state of the art of integrated fiber-wireless (FiWi broadband access networks in great detail, we briefly review recent progress and point to various ongoing research activities, including the design of energy-efficient “green” FiWi access networks, advanced survivability techniques, and integration of wireless and fiber optic sensors, towards realizing adaptable, dependable, and ecoconscious future-proof broadband access networks based on both wireless and shared passive fiber media. Furthermore, we discuss service, application, business, and operation related aspects, which motivate access technology to move into a substantially different direction in the long run than continued capacity provisioning. Given that most 4G cellular mobile network researches so far have been focusing on the achievable performance gains in the wireless front-end only without looking into the details of backhaul implementations and possible backhaul bottlenecks, we identify open key research challenges for FiWi broadband access networks. We explore ways of how they can be deployed across relevant economic sectors other than telecommunications per se, taking major paradigm shifts such as the Third Industrial Revolution, Energy Internet, smart grid, and explosion of mobile data traffic in today’s cellular networks into account.

  20. Measuring the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pollock, B. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shaw, J. L. [Univ. of California, Los Angeles, CA (United States); Marsh, K. A. [Univ. of California, Los Angeles, CA (United States); Ralph, J. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chen, Y. -H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pak, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Clayton, C. E. [Univ. of California, Los Angeles, CA (United States); Glenzer, S. H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Joshi, C. [Univ. of California, Los Angeles, CA (United States)

    2014-07-22

    This paper presents a new technique to measure the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator. Measurements are performed with a stacked image plates spectrometer, capable of detecting broadband x-ray radiation up to 1 MeV. It can provide measurements of the betatron x-ray spectrum at any angle of observation (within a 40 mrad cone) and of the beam profile. A detailed description of our data analysis is given, along with comparison for several shots. As a result, these measurements provide useful information on the dynamics of the electrons are they are accelerated and wiggled by the wakefield.

  1. Continuous probing of cold complex molecules with infrared frequency comb spectroscopy

    Science.gov (United States)

    Spaun, Ben; Changala, P. Bryan; Patterson, David; Bjork, Bryce J.; Heckl, Oliver H.; Doyle, John M.; Ye, Jun

    2016-05-01

    For more than half a century, high-resolution infrared spectroscopy has played a crucial role in probing molecular structure and dynamics. Such studies have so far been largely restricted to relatively small and simple systems, because at room temperature even molecules of modest size already occupy many millions of rotational/vibrational states, yielding highly congested spectra that are difficult to assign. Targeting more complex molecules requires methods that can record broadband infrared spectra (that is, spanning multiple vibrational bands) with both high resolution and high sensitivity. However, infrared spectroscopic techniques have hitherto been limited either by narrow bandwidth and long acquisition time, or by low sensitivity and resolution. Cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) combines the inherent broad bandwidth and high resolution of an optical frequency comb with the high detection sensitivity provided by a high-finesse enhancement cavity, but it still suffers from spectral congestion. Here we show that this problem can be overcome by using buffer gas cooling to produce continuous, cold samples of molecules that are then subjected to CE-DFCS. This integration allows us to acquire a rotationally resolved direct absorption spectrum in the C–H stretching region of nitromethane, a model system that challenges our understanding of large-amplitude vibrational motion. We have also used this technique on several large organic molecules that are of fundamental spectroscopic and astrochemical relevance, including naphthalene, adamantane and hexamethylenetetramine. These findings establish the value of our approach for studying much larger and more complex molecules than have been probed so far, enabling complex molecules and their kinetics to be studied with orders-of-magnitude improvements in efficiency, spectral resolution and specificity.

  2. Coherent-subspace array processing based on wavelet covariance: an application to broad-band, seismo-volcanic signals

    Science.gov (United States)

    Saccorotti, G.; Nisii, V.; Del Pezzo, E.

    2008-07-01

    Long-Period (LP) and Very-Long-Period (VLP) signals are the most characteristic seismic signature of volcano dynamics, and provide important information about the physical processes occurring in magmatic and hydrothermal systems. These events are usually characterized by sharp spectral peaks, which may span several frequency decades, by emergent onsets, and by a lack of clear S-wave arrivals. These two latter features make both signal detection and location a challenging task. In this paper, we propose a processing procedure based on Continuous Wavelet Transform of multichannel, broad-band data to simultaneously solve the signal detection and location problems. Our method consists of two steps. First, we apply a frequency-dependent threshold to the estimates of the array-averaged WCO in order to locate the time-frequency regions spanned by coherent arrivals. For these data, we then use the time-series of the complex wavelet coefficients for deriving the elements of the spatial Cross-Spectral Matrix. From the eigenstructure of this matrix, we eventually estimate the kinematic signals' parameters using the MUltiple SIgnal Characterization (MUSIC) algorithm. The whole procedure greatly facilitates the detection and location of weak, broad-band signals, in turn avoiding the time-frequency resolution trade-off and frequency leakage effects which affect conventional covariance estimates based upon Windowed Fourier Transform. The method is applied to explosion signals recorded at Stromboli volcano by either a short-period, small aperture antenna, or a large-aperture, broad-band network. The LP (0.2 2s) of the explosion recordings from the broad-band network. Source locations obtained this way are fully compatible with those retrieved from application of more traditional (and computationally expensive) time-domain techniques, such as the Radial Semblance method.

  3. Qualitative interpretation of galaxy spectra

    CERN Document Server

    Almeida, J Sanchez; Terlevich, E; Fernandes, R Cid; Morales-Luis, A B

    2012-01-01

    We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis, and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is of general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7 (SDSS-DR7), thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to HII galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. A number of byprodu...

  4. Source localization of turboshaft engine broadband noise using a three-sensor coherence method

    Science.gov (United States)

    Blacodon, Daniel; Lewy, Serge

    2015-03-01

    Turboshaft engines can become the main source of helicopter noise at takeoff. Inlet radiation mainly comes from the compressor tones, but aft radiation is more intricate: turbine tones usually are above the audible frequency range and do not contribute to the weighted sound levels; jet is secondary and radiates low noise levels. A broadband component is the most annoying but its sources are not well known (it is called internal or core noise). Present study was made in the framework of the European project TEENI (Turboshaft Engine Exhaust Noise Identification). Its main objective was to localize the broadband sources in order to better reduce them. Several diagnostic techniques were implemented by the various TEENI partners. As regards ONERA, a first attempt at separating sources was made in the past with Turbomeca using a three-signal coherence method (TSM) to reject background non-acoustic noise. The main difficulty when using TSM is the assessment of the frequency range where the results are valid. This drawback has been circumvented in the TSM implemented in TEENI. Measurements were made on a highly instrumented Ardiden turboshaft engine in the Turbomeca open-air test bench. Two engine powers (approach and takeoff) were selected to apply TSM. Two internal pressure probes were located in various cross-sections, either behind the combustion chamber (CC), the high-pressure turbine (HPT), the free-turbine first stage (TL), or in four nozzle sections. The third transducer was a far-field microphone located around the maximum of radiation, at 120° from the intake centerline. The key result is that coherence increases from CC to HPT and TL, then decreases in the nozzle up to the exit. Pressure fluctuations from HPT and TL are very coherent with the far-field acoustic spectra up to 700 Hz. They are thus the main acoustic source and can be attributed to indirect combustion noise (accuracy decreases above 700 Hz because coherence is lower, but far-field sound spectra

  5. Broadband circular polarizers constructed using helix-like chiral metamaterials

    Science.gov (United States)

    Ji, Ruonan; Wang, Shao-Wei; Liu, Xingxing; Chen, Xiaoshuang; Lu, Wei

    2016-08-01

    In this paper, one kind of helix-like chiral metamaterial which can be realized by multiple conventional lithography or electron beam lithographic techniques is proposed to have a broadband bianisotropic optical response analogous to helical metamaterials. On the basis of twisted metamaterials, via tailoring the relative orientation within the lattice, the anisotropy of arcs is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed into the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical response. For only a four-layer helix-like metamaterial, the maximum extinction ratio can reach 19.7. The operation band is in the wavelength range of 4.69 μm to 8.98 μm with an average extinction ratio of 6.9. And the transmittance for selective polarization is above 0.8 in the entire operation band. Such a structure is a promising candidate for integratable and scalable broadband circular polarizers, especially it has great potential to act as a broadband circular micropolarizer in the field of the full-Stokes division of focal plane polarimeters.In this paper, one kind of helix-like chiral metamaterial which can be realized by multiple conventional lithography or electron beam lithographic techniques is proposed to have a broadband bianisotropic optical response analogous to helical metamaterials. On the basis of twisted metamaterials, via tailoring the relative orientation within the lattice, the anisotropy of arcs is converted into magneto-electric coupling of closely spaced arc pairs, which leads to a broad bianisotropic optical response. By connecting the adjacent upper and lower arcs, the coupling of metasurface pairs is transformed into the coupling of the three-dimensional inclusions, and provides a much broader and higher bianisotropic optical

  6. Cascaded four-wave mixing for broadband tunable laser sideband generation.

    Science.gov (United States)

    Liu, Weimin; Zhu, Liangdong; Wang, Liang; Fang, Chong

    2013-06-01

    We demonstrate the versatile broadband wavelength tunability of frequency upconverted multicolor cascaded four-wave-mixing (CFWM) signals spanning the continuous wavelength range from UV to near IR in a thin type-I BBO crystal using 35 fs, 800 nm fundamental and chirped IR supercontinuum white light pulses. Two sets of spatially dispersed CFWM laser sidebands are concomitantly generated from two incident pulses as well as their second-harmonic-generation and sum-frequency-generation pulses in a crossing geometry. The tunable cascaded signals with ultrabroad bandwidth can be readily achieved via spatially rotating the BBO crystal to different phase-matching conditions and temporally varying the time delay between the two incident near-IR pulses.

  7. Broadband optically controlled switching effect in a microfluid-filled photonic bandgap fiber

    Science.gov (United States)

    Guo, Junqi; Liu, Yan-ge; Wang, Zhi; Luo, Mingming; Huang, Wei; Han, Tingting; Liu, Xiaoqi

    2016-05-01

    Broadband optically controlled switching in a microfluid-filled photonic bandgap fiber (MF-PBGF) was observed and investigated. The MF-PBGF was formed by infusing a temperature-sensitive high-index fluid into all of the cladding holes of a microstructured optical fiber (MOF). The fiber was then side pumped with a 532 nm continuous wave laser. An extinction ratio of greater than 20 dB at most of the bandgap wavelengths (more than 200 nm) was obtained with a switching power of ∼147 mW. Theoretical and experimental investigations revealed that the effect originated from changes in the temperature gradient induced by heat absorption of the fiber coating with laser illumination. These investigations offer a new and simple approach to achieve wideband and flexible all-optical fiber switching devices without using any photosensitive materials.

  8. Cascaded four-wave mixing for broadband tunable laser sideband generation.

    Science.gov (United States)

    Liu, Weimin; Zhu, Liangdong; Wang, Liang; Fang, Chong

    2013-06-01

    We demonstrate the versatile broadband wavelength tunability of frequency upconverted multicolor cascaded four-wave-mixing (CFWM) signals spanning the continuous wavelength range from UV to near IR in a thin type-I BBO crystal using 35 fs, 800 nm fundamental and chirped IR supercontinuum white light pulses. Two sets of spatially dispersed CFWM laser sidebands are concomitantly generated from two incident pulses as well as their second-harmonic-generation and sum-frequency-generation pulses in a crossing geometry. The tunable cascaded signals with ultrabroad bandwidth can be readily achieved via spatially rotating the BBO crystal to different phase-matching conditions and temporally varying the time delay between the two incident near-IR pulses. PMID:23722739

  9. Generalized Continued Logarithms and Related Continued Fractions

    OpenAIRE

    Borwein, Jonathan M.; Hare, Kevin G.; Lynch, Jason G.

    2016-01-01

    We study continued logarithms as introduced by Bill Gosper and studied by J. Borwein et. al.. After providing an overview of the type I and type II generalizations of binary continued logarithms introduced by Borwein et. al., we focus on a new generalization to an arbitrary integer base $b$. We show that all of our so-called type III continued logarithms converge and all rational numbers have finite type III continued logarithms. As with simple continued fractions, we show that the continued ...

  10. QUALITATIVE INTERPRETATION OF GALAXY SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Almeida, J.; Morales-Luis, A. B. [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Terlevich, R.; Terlevich, E. [Instituto Nacional de Astrofisica, Optica y Electronica, Tonantzintla, Puebla (Mexico); Cid Fernandes, R., E-mail: jos@iac.es, E-mail: abml@iac.es, E-mail: rjt@ast.cam.ac.uk, E-mail: eterlevi@inaoep.mx, E-mail: cid@astro.ufsc.br [Departamento de Fisica-CFM, Universidade Federal de Santa Catarina, P.O. Box 476, 88040-900 Florianopolis, SC (Brazil)

    2012-09-10

    We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is for general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means-based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7, thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to H II galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code STARLIGHT. We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature-based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a one-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal-rich or metal-poor depending on whether they reside in passive galaxies or in star-forming galaxies.

  11. Automatic identification of mass spectra

    International Nuclear Information System (INIS)

    Several approaches to preprocessing and comparison of low resolution mass spectra have been evaluated by various test methods related to library search. It is shown that there is a clear correlation between the nature of any contamination of a spectrum, the basic principle of the transformation or distance measure, and the performance of the identification system. The identification of functionality from low resolution spectra has also been evaluated using several classification methods. It is shown that there is an upper limit to the success of this approach, but also that this can be improved significantly by using a very limited amount of additional information. 10 refs

  12. AVIRIS spectra of California wetlands

    Science.gov (United States)

    Gross, Michael F.; Ustin, Susan L.; Klemas, Vytautas

    1988-01-01

    Spectral data gathered by the AVIRIS from wetlands in the Suisun Bay area of California on 13 October 1987 were analyzed. Spectra representing stands of numerous vegetation types (including Sesuvium verrucosum, Scirpus acutus and Scirpus californicus, Xanthium strumarium, Cynadon dactylon, and Distichlis spicata) and soil were isolated. Despite some defects in the data, it was possible to detect vegetation features such as differences in the location of the chlorophyll red absorption maximum. Also, differences in cover type spectra were evident in other spectral regions. It was not possible to determine if the observed features represent noise, variability in canopy architecture, or chemical constituents of leaves.

  13. Broadband and chiral binary dielectric meta-holograms

    Science.gov (United States)

    Khorasaninejad, Mohammadreza; Ambrosio, Antonio; Kanhaiya, Pritpal; Capasso, Federico

    2016-01-01

    Subwavelength structured surfaces, known as meta-surfaces, hold promise for future compact and optically thin devices with versatile functionalities. By revisiting the concept of detour phase, we demonstrate high-efficiency holograms with broadband and chiral imaging functionalities. In our devices, the apertures of binary holograms are replaced by subwavelength structured microgratings. We achieve broadband operation from the visible to the near infrared and efficiency as high as 75% in the 1.0 to 1.4 μm range by compensating for the inherent dispersion of the detour phase with that of the subwavelength structure. In addition, we demonstrate chiral holograms that project different images depending on the handedness of the reference beam by incorporating a geometric phase. Our devices’ compactness, lightness, and ability to produce images even at large angles have significant potential for important emerging applications such as wearable optics. PMID:27386518

  14. Broadband terahertz metamaterial absorber based on sectional asymmetric structures

    Science.gov (United States)

    Gong, Cheng; Zhan, Mingzhou; Yang, Jing; Wang, Zhigang; Liu, Haitao; Zhao, Yuejin; Liu, Weiwei

    2016-01-01

    We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber’s working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber’s each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging. PMID:27571941

  15. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    Science.gov (United States)

    Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-02-01

    Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region. PMID:26907442

  16. Broadband electrostatic acoustic transducer for ultrasonic measurements in liquids.

    Science.gov (United States)

    Cantrell, J H; Heyman, J S; Yost, W T; Torbett, M A; Breazeale, M A

    1979-01-01

    A broadband capacitive electrostatic acoustic transducer (ESAT) has been developed for use in a liquid environment at megahertz frequencies. The ESAT basically consists of a thin conductive membrane stretched over a metallic housing. The membrane functions as the ground plate of a parallel plate capacitor, the other plate being a dc biased electrode recessed approximately 10 mum from the electrically grounded membrane. An ultrasonic wave incident on the membrane varies the membrane-electrode gap spacing and generates an electrical signal proportional to the wave amplitude. The entire assembly is sealed for immersion in a liquid environment. Calibration of the ESAT with incident ultrasonic waves of constant displacement amplitude from 1 to 15 MHz reveals a decrease in signal response with increasing frequency independent of membrane tension. The use of the ESAT as a broadband ultrasonic transducer in liquids with a predictable frequency response is promising.

  17. Broadband detuned Sagnac interferometer for future generation gravitational wave astronomy

    CERN Document Server

    Voronchev, N V; Danilishin, S L

    2015-01-01

    Broadband suppression of quantum noise below the Standard Quantum Limit (SQL) becomes a top-priority problem for the future generation of large-scale terrestrial detectors of gravitational waves, as the interferometers of the Advanced LIGO project, predesigned to be quantum-noise-limited in the almost entire detection band, are phased in. To this end, among various proposed methods of quantum noise suppression or signal amplification, the most elaborate approach implies a so-called *xylophone* configuration of two Michelson interferometers, each optimised for its own frequency band, with a combined broadband sensitivity well below the SQL. Albeit ingenious, it is a rather costly solution. We demonstrate that changing the optical scheme to a Sagnac interferometer with weak detuned signal recycling and frequency dependent input squeezing can do almost as good a job, as the xylophone for significantly lower spend. We also show that the Sagnac interferometer is more robust to optical loss in filter cavity, used f...

  18. Photonic crystals for broadband, omnidirectional self-collimation

    Science.gov (United States)

    Chuang, Y.-C.; Suleski, T. J.

    2011-03-01

    In this paper, multiple photonic crystal (PC) structures are proposed to improve three-dimensional (3D) self-collimation performance, including two 3D PCs (tetragonal lattice structures and a complex hexagonal lattice structure) and two two-dimensional (2D) PCs (triangular lattice structures and kagome lattice structures) with out-of-plane orientation. Different design strategies are investigated and compared in terms of the resulting self-collimation performance. Several desired 3D properties are numerically realized for the first time, including broadband 3D self-collimation, omnidirectional beam confinement and broadband omnidirectional self-collimation. These developments can enable future self-collimation applications, such as multiplexers, PC core fibers and solar light collection.

  19. Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

    KAUST Repository

    Adachi, Michael M

    2013-10-14

    Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

  20. Research on Raman Crosstalk in Broadband Wavelength Division Multiplexed Systems

    Institute of Scientific and Technical Information of China (English)

    XUE Fei; QIU Kun

    2004-01-01

    After a theoretical model is put forward on the base of accurate description of the Raman gain profile and the physical quantity,maximum Raman crosstalk(MRC),which quantificationally depicts the intensity of Raman crosstalk is defined.The influences of launch power,fiber effective core area,fiber nonlinear index,fiber length,channel number and channel interval on MRC are deduced.The result indicates that compared with low speed and narrowband optical fiber communication system,serious Raman crosstalk lies in high speed and broadband system,which impacts the performance of the system badly.The result is useful for forecasting Raman crosstalk in broadband and high speed optical fiber communication system.

  1. Swift/BAT and MAXI/GSC broadband transient monitor

    Science.gov (United States)

    Sakamoto, Takanori; Oda, Ryoma; Mihara, Tatehiro; Yoshida, Atsumasa; Arimoto, Makoto; Barthelmy, Scott D.; Kawai, Nobuyuki; Krimm, Hans A.; Nakahira, Satoshi; Serino, Motoko

    2016-06-01

    We present a newly developed broadband transient monitor using the Swift Burst Alert Telescope (BAT) and the MAXI Gas Slit Camera (GSC) data. Our broadband transient monitor keeps vigil for high-energy transient sources from 2 keV to 200 keV in seven energy bands by combining the BAT (15-200 keV) and the GSC (2-20 keV) data. Currently, daily and 90-minute (one orbit) averaged light curves are available for 106 high-energy transient sources. This transient monitor is available to the public through our web server, http://yoshidalab.mydns.jp/bat_gsc_trans_mon/, for wider use by the community. We discuss a daily sensitivity of our monitor and possible future improvements on our pipeline.

  2. Broadband laser polarization control with aligned carbon nanotubes

    CERN Document Server

    Yang, He; Lia, Diao; Chen, Ya; Mattila, Marco; Tian, Ying; Yong, Zhenzhong; Yang, Changxi; Tittonen, Ilkka; Ren, Zhaoyu; Bai, Jingtao; Li, Qingwen; Kauppinen, Esko I; Lipsanen, Harri; Sun, Zhipei

    2015-01-01

    We introduce a simple approach to fabricate aligned carbon nanotube (ACNT) device for broadband polarization control in fiber laser systems. The ACNT device was fabricated by pulling from as-fabricated vertically-aligned carbon nanotube arrays. Their anisotropic property is confirmed with optical and scanning electron microscopy, and with polarized Raman and absorption spectroscopy. The device was then integrated into fiber laser systems (at two technologically important wavelengths of 1 and 1.5 um) for polarization control. We obtained a linearly-polarized light output with the maximum extinction ratio of ~12 dB. The output polarization direction could be fully controlled by the ACNT alignment direction in both lasers. To the best of our knowledge, this is the first time that ACNT device is applied to polarization control in laser systems. Our results exhibit that the ACNT device is a simple, low-cost, and broadband polarizer to control laser polarization dynamics, for various photonic applications (such as ...

  3. Broadband second harmonic generation in whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Strekalov, Dmitry V; Yu, Nan

    2013-01-01

    Optical frequency conversion processes in nonlinear materials are limited in wavelength by the accessible phase matching and the required high pump powers. In this letter, we report a novel broadband phase matching (PM) technique in high quality factor (Q) whispering gallery mode (WGM) resonators made of birefringent crystalline materials. This technique relies on two interacting WGMs, one with constant and the other with spatially oscillating phase velocity. Thus, phase matching occurs cyclically. The technique can be implemented with a WGM resonator with its disk plane parallel to the optic axis of the crystal. With a single beta barium borate (BBO) resonator in that configuration, we experimentally demonstrated efficient second harmonic generation (SHG) to harmonic wavelengths from 780 nm in the near infrared to 317 nm in the ultraviolet (UV). The observed SHG conversion efficiency is as high as 4.6% (mW)-1. This broadband PM technique opens a new way for nonlinear optics applications in WGM resonators. Th...

  4. Amplifier based broadband pixel for sub-millimeter wave imaging

    Science.gov (United States)

    Sarkozy, Stephen; Drewes, Jonathan; Leong, Kevin M. K. H.; Lai, Richard; Mei, X. B. (Gerry); Yoshida, Wayne; Lange, Michael D.; Lee, Jane; Deal, William R.

    2012-09-01

    Broadband sub-millimeter wave technology has received significant attention for potential applications in security, medical, and military imaging. Despite theoretical advantages of reduced size, weight, and power compared to current millimeter wave systems, sub-millimeter wave systems have been hampered by a fundamental lack of amplification with sufficient gain and noise figure properties. We report a broadband pixel operating from 300 to 340 GHz, biased off a single 2 V power supply. Over this frequency range, the amplifiers provide > 40 dB gain and 1.0 THz. The first sub-millimeter wave-based images using active amplification are demonstrated as part of the Joint Improvised Explosive Device Defeat Organization Longe Range Personnel Imager Program. This development and demonstration may bring to life future sub-millimeter-wave and THz applications such as solutions to brownout problems, ultra-high bandwidth satellite communication cross-links, and future planetary exploration missions.

  5. A Performance Study of Wireless Broadband Access (WiMAX

    Directory of Open Access Journals (Sweden)

    Maan A. S. Al-Adwany

    2011-12-01

    Full Text Available WiMAX (worldwide interoperability for microwave access is one of the wireless broadband access technologies which supplies broadband services to clients, but it surpasses other technologies by its coverage area, where one base station can cover a small city. In this paper, WiMAX technology is studied by exploring its basic concepts, applications, and advantages / disadvantages. Also a MATLAB simulator is used to verify the operation of the WiMAX system under various channel impairments and for variety of modulation schemes. From the simulation results, we found that WiMAX system works well in both AWGN and multipath fading channels, but under certain constraints that are addressed in this paper.

  6. Planar metamaterial-based beam-scanning broadband microwave antenna

    Energy Technology Data Exchange (ETDEWEB)

    Dhouibi, Abdallah [IEF, CNRS, UMR 8622, Univ. Paris-Sud, 91405 Orsay Cedex (France); Burokur, Shah Nawaz, E-mail: shah-nawaz.burokur@u-psud.fr; Lustrac, André de [IEF, CNRS, UMR 8622, Univ. Paris-Sud, 91405 Orsay Cedex (France); Univ. Paris-Ouest, 92410 Ville d' Avray (France)

    2014-05-21

    The broadband directive emission from the use of waveguided metamaterials is numerically and experimentally reported. The metamaterials, which are composed of non-resonant circular complementary closed ring structures printed on a dielectric substrate, are designed to obey the refractive index of a Luneburg lens. An arc array of planar radiating slot antennas placed at the periphery of the lens is used as wave launchers. A prototype of the lens associated with the feed structures has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, far-field radiation patterns have been measured. Furthermore, this metamaterial-based lens can be used to achieve beam-scanning with a coverage of up to 120 °. Far-field measurements agree qualitatively with calculated near-field distributions.

  7. Radiative cooling and broadband phenomenon in low-frequency waves

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, we analyze the effects of radiative cooling on the pure baroclinic low-frequency waves under the approximation of equatorial -plane and semi-geostrophic condition. The results show that radiative cooling does not, exclusively, provide the damping effects on the development of low-frequency waves. Under the delicate radiative-convective equilibrium, radiative effects will alter the phase speed and wave period, and bring about the broadband of phase velocity and wave period by adjusting the vertical profiles of diabatic heating. when the intensity of diabatic heating is moderate and appropriate, it is conductive to the development and sustaining of the low-frequency waves and their broadband phenomena, not the larger, the better. The radiative cooling cannot be neglected in order to reach the moderate and appropriate intensity of diabatic heating.

  8. Broadband terahertz generation and detection at 10 nm scale.

    Science.gov (United States)

    Ma, Yanjun; Huang, Mengchen; Ryu, Sangwoo; Bark, Chung Wung; Eom, Chang-Beom; Irvin, Patrick; Levy, Jeremy

    2013-06-12

    Terahertz (0.1-30 THz) radiation reveals a wealth of information that is relevant for material, biological, and medical sciences with applications that span chemical sensing, high-speed electronics, and coherent control of semiconductor quantum bits. To date, there have been no methods capable of controlling terahertz (THz) radiation at molecular scales. Here we report both generation and detection of broadband terahertz field from 10 nm scale oxide nanojunctions. Frequency components of ultrafast optical radiation are mixed at these nanojunctions, producing broadband THz emission. These same devices detect THz electric fields with comparable spatial resolution. This unprecedented control, on a scale of 4 orders of magnitude smaller than the diffraction limit, creates a pathway toward THz-bandwidth spectroscopy and control of individual nanoparticles and molecules.

  9. Broadband and chiral binary dielectric meta-holograms.

    Science.gov (United States)

    Khorasaninejad, Mohammadreza; Ambrosio, Antonio; Kanhaiya, Pritpal; Capasso, Federico

    2016-05-01

    Subwavelength structured surfaces, known as meta-surfaces, hold promise for future compact and optically thin devices with versatile functionalities. By revisiting the concept of detour phase, we demonstrate high-efficiency holograms with broadband and chiral imaging functionalities. In our devices, the apertures of binary holograms are replaced by subwavelength structured microgratings. We achieve broadband operation from the visible to the near infrared and efficiency as high as 75% in the 1.0 to 1.4 μm range by compensating for the inherent dispersion of the detour phase with that of the subwavelength structure. In addition, we demonstrate chiral holograms that project different images depending on the handedness of the reference beam by incorporating a geometric phase. Our devices' compactness, lightness, and ability to produce images even at large angles have significant potential for important emerging applications such as wearable optics. PMID:27386518

  10. Tone and Broadband Noise Separation from Acoustic Data of a Scale-Model Counter-Rotating Open Rotor

    Science.gov (United States)

    Sree, David; Stephens, David B.

    2014-01-01

    Renewed interest in contra-rotating open rotor technology for aircraft propulsion application has prompted the development of advanced diagnostic tools for better design and improved acoustical performance. In particular, the determination of tonal and broadband components of open rotor acoustic spectra is essential for properly assessing the noise control parameters and also for validating the open rotor noise simulation codes. The technique of phase averaging has been employed to separate the tone and broadband components from a single rotor, but this method does not work for the two-shaft contra-rotating open rotor. A new signal processing technique was recently developed to process the contra-rotating open rotor acoustic data. The technique was first tested using acoustic data taken of a hobby aircraft open rotor propeller, and reported previously. The intent of the present work is to verify and validate the applicability of the new technique to a realistic one-fifth scale open rotor model which has 12 forward and 10 aft contra-rotating blades operating at realistic forward flight Mach numbers and tip speeds. The results and discussions of that study are presented in this paper.

  11. Tone and Broadband Noise Separation from Acoustic Data of a Scale-Model Contra-Rotating Open Rotor

    Science.gov (United States)

    Sree, Dave; Stephens, David B.

    2014-01-01

    Renewed interest in contra-rotating open rotor technology for aircraft propulsion application has prompted the development of advanced diagnostic tools for better design and improved acoustical performance. In particular, the determination of tonal and broadband components of open rotor acoustic spectra is essential for properly assessing the noise control parameters and also for validating the open rotor noise simulation codes. The technique of phase averaging has been employed to separate the tone and broadband components from a single rotor, but this method does not work for the two-shaft contra-rotating open rotor. A new signal processing technique was recently developed to process the contra-rotating open rotor acoustic data. The technique was first tested using acoustic data taken of a hobby aircraft open rotor propeller, and reported previously. The intent of the present work is to verify and validate the applicability of the new technique to a realistic one-fifth scale open rotor model which has 12 forward and 10 aft contra-rotating blades operating at realistic forward flight Mach numbers and tip speeds. The results and discussions of that study are presented in this paper.

  12. Ultra-Broadband Acoustic Metasurface for Manipulating the Reflected Waves

    OpenAIRE

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2014-01-01

    We have designed and experimentally realized an ultra-broadband acoustic metasurface (UBAM) capable of going beyond the intrinsic limitation of bandwidth in existing designs of optical/acoustical metasurfaces. Both the numerical and experimental results demonstrate that the UBAM made of subwavelength gratings can manipulate the reflected phase-front within a bandwidth larger than 2 octaves. A simple physical model based on the phased array theory is developed for interpreting this extraordina...

  13. Fiber Optic Broadband Ultrasonic Probe for Virtual Biopsy: Technological Solutions

    OpenAIRE

    Biagi, E.; Cerbai, S.; Masotti, L.; L. Belsito; A. RONCAGLIA; Masetti, G.; N. Speciale

    2010-01-01

    An ultrasonic probe was developed by using, in conjunction, optoacoustic and acousto-optic devices based on fiber optic technology. The intrinsic high frequency and wide bandwidth associated both to the opto-acoustic source and to the acousto-optic receiving element could open a way towards a “virtual biopsy” of biological tissue. A Micro-Opto-Mechanical-System (MOMS) approach is proposed to realize the broadband ultrasonic probe on micromachined silicon frames suited to be mounted on the tip...

  14. Entry Threat and Entry Deterrence: The Timing of Broadband Rollout

    OpenAIRE

    Mo Xiao; Orazem, Peter F.

    2007-01-01

    Past empirical literature provides strong evidence that competition increases when new firms enter a market. However, rarely have economists been able to examine how competition changes with the threat of entry. This paper uses the evolution of the zip code level market structure of facilities-based broadband providers from 1999 to 2004 to investigate how a firm adjusts its entry strategy when facing the threat of additional entrants. We identify the potential entrant into a local market as t...

  15. A Novel, Free-Space Broadband Dielectric Measurement Technique

    OpenAIRE

    Liu, Yaqiang

    2014-01-01

    Frequently, when free-space electromagnetic waves pass through a material, there will be some form of interaction between the wave and the material. Measuring this change forms the basis of free-space, dielectric material measurement, where the variations will be attenuation and a phase change relative to the wave when the material was not present and are typically recorded over a broadband range of frequencies. In this work a new technique is presented to accurately perform free-space bro...

  16. Broadband sum frequency generation via chirped quasi-phase-matching

    OpenAIRE

    Rangelov, A. A.; Vitanov, N. V.

    2011-01-01

    An efficient broadband sum frequency generation (SFG) technique using the two collinear optical parametric processes \\omega 3=\\omega 1+\\omega 2 and \\omega 4=\\omega 1+\\omega 3 is proposed. The technique uses chirped quasi-phase-matched gratings, which, in the undepleted pump approximation, make SFG analogous to adiabatic population transfer in three-state systems with crossing energies in quantum physics. If the local modulation period %for aperiodically poled quasi-phase-matching first makes ...

  17. Design of a Broadband Inverted Conical Quadrifilar Helix Antenna

    OpenAIRE

    Jingyan Mo; Wei Liu; Weidong Fang; Haigao Xue; Zhongchao Lin

    2016-01-01

    This paper introduces the design of a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA). The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values...

  18. Broadband Wireless Channel measurements for high speed trains

    OpenAIRE

    Kaltenberger, Florian; BYIRINGIRO, Auguste; Arvanitakis, George; GHADDAB, Ryad; NUSSBAUM, Dominique; Knopp, Raymond; Berbineau, Marion; Cocheril, Yann; Philippe, Henri

    2014-01-01

    We describe a channel sounding measurement campaign for cellular broadband wireless communications with high speed trains that was carried out in the context of the project CORRIDOR. The campaign combines MIMO and carrier aggregation to achieve very highth roughputs. We compare two different scenarios, the first one reflects a cellular deployment, where the base station is about 1 km away from the railway line. The second scenario corresponds to a railway deployed network, where the base stat...

  19. Broadband bow-tie antenna with tapered balun

    OpenAIRE

    Jaafar, Hussein Mohammed

    2014-01-01

    ABSTRACT: In microwave applications spectrum Industrial, Scientific and Medical (ISM) band, especially in wireless communication systems applications such as GSM, 3G, Wi-Fi and Wi-MAX applications, high antenna characteristics such as high gain and wide bandwidth are required. In this thesis, a broadband Bow Tie Antenna (BTA) with high performance characteristics has been designed, to cover the wireless application requirements. One of the fundamental problems of the transmission line in the ...

  20. Experimental demonstration of quantum teleportation of broadband squeezing

    OpenAIRE

    Yonezawa, Hidehiro; Braunstein, Samuel L.; Furusawa, Akira

    2007-01-01

    We demonstrate an unconditional high-fidelity teleporter capable of preserving the broadband entanglement in an optical squeezed state. In particular, we teleport a squeezed state of light and observe $-0.8 \\pm 0.2$dB of squeezing in the teleported (output) state. We show that the squeezing criterion translates directly into a sufficient criterion for entanglement of the upper and lower sidebands of the optical field. Thus, this result demonstrates the first unconditional teleportation of bro...